MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Plant and Cell Physiology' source. Sun, 21 Mar 2010 17:33:23 +0100 http://www.medworm.com/index.php?rid=3350131&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F486%3Frss%3D1 Heat shock transcription factor A2 (HsfA2) is induced under environmental stress and regulates transcription of various defense-related genes. Thus HsfA2 plays an important role in induction of defenses against different types of environmental stress, but its mode of regulation remains unknown. To clarify the signal transduction pathway involved in the regulation of HsfA2 expression, we investigated the effect of MG132, a 26S proteasome inhibitor, or geldanamycin (GDA), a heat shock protein 90 (Hsp90) inhibitor, on the transcription of HsfA2 and its targets, Hsp18.1-CI and ascorbate peroxidase 2 (Apx2), in Arabidopsis T87 cells. The levels of transcripts were significantly increased by treatment with MG132 or GDA. Overexpression of a dexamethazone-inducible dominant-negative form of Hsp90.... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350131 Wed, 10 Mar 2010 06:01:15 +0100 3350131 http://www.medworm.com/index.php?rid=3350130&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F475%3Frss%3D1 In this study, we isolated a rice mutant showing leaf chlorosis at the early seedling stage but inhibition of root growth during the whole growth period. Genetic analysis demonstrates that the phenotypes of the mutant were caused by a recessive single gene mutation. The mutated gene was cloned by map-based cloning, and was shown to encode an SPP. Sequence analysis showed a glutamate deletion in the highly conserved C-terminus of SPP in the mutant. The mutation of SPP in the mutant was verified by transgenic complementation. SPP is constitutively expressed in all tissues. Subcellular localization analysis indicates that SPP is targeted to the chloroplast. The expression of some genes associated with chloroplast development was decreased in young seedlings of the spp mutant, but not in 14-da... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350130 Wed, 10 Mar 2010 06:01:15 +0100 3350130 http://www.medworm.com/index.php?rid=3350129&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F463%3Frss%3D1 Anthocyanins are secondary metabolites that contribute to colors of flowers, fruits and leaves. Asiatic hybrid lily (Lilium spp.) accumulates cyanidin anthocyanins in flower tepals, tepal spots and leaves of juvenile shoots. To clarify their mechanisms of regulation of anthocyanin pigmentation, two full-length cDNAs of R2R3-MYB (LhMYB6 and LhMYB12) were isolated from the anthocyanin-accumulating tepals of cultivar ‘Montreux’. Analysis of the deduced amino acid sequences indicated they have homology with petunia AN2, homologous sequences of which had not been isolated in species of monocots. Yeast two-hybrid analysis showed that LhMYB6 and LhMYB12 interacted with the Lilium hybrid basic helix–loop–helix 2 (LhbHLH2) protein. Transient expression analysis indicated tha... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350129 Wed, 10 Mar 2010 06:01:15 +0100 3350129 http://www.medworm.com/index.php?rid=3350128&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F448%3Frss%3D1 Abiotic stress influences the translation of mRNAs in plants. To gain a global view of the early translational response to abiotic stress, we investigated genome-wide changes in mRNA translation in Arabidopsis thaliana suspension cell cultures exposed to brief periods of two types of stress: elevated temperature (37°C) and high salinity (200 mM NaCl). Microarray analyses revealed that polysome association of most transcripts, which were monitored by using polysomal- and non-polysomal-associated RNA pools, was variably depressed by both stresses within 10 min. We also inspected coordination of changes in translational profiles with transcriptional profiles, and found no simple correlations between the changes in these two processes under both stresses. In addition, we uncovered that the... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350128 Wed, 10 Mar 2010 06:01:15 +0100 3350128 http://www.medworm.com/index.php?rid=3350127&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F435%3Frss%3D1 The genetic and phenotypic characterization of a new tomato (Solanum lycopersicum) insertional mutant, Arlequin (Alq) is reported. Alq mutant plants were affected in reproductive development and their sepals were homeotically converted into fleshy fruit-like organs. Molecular analysis demonstrated that a single copy of T-DNA was present in the mutant genome while genetic analysis confirmed that the mutant phenotype co-segregated with the T-DNA insertion and was inherited as a monogenic semi-dominant trait. The histological and scanning electron microscope analyses revealed cell identity changes in both external and internal tissues of Alq sepals. Flowers developed by Alq homozygous plants showed a severe mutant phenotype, since after fruit set, not only did the sepals become succulent but ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350127 Wed, 10 Mar 2010 06:01:15 +0100 3350127 http://www.medworm.com/index.php?rid=3350126&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F422%3Frss%3D1 Polyamine (PA) levels in plants increase considerably under saline conditions. Because such an increase is believed to be beneficial for stress resistance, exogenous application of PAs has often been advocated as a means of ameliorating the detrimental effects of salinity. Results, however, are rather controversial, ranging from a significant amelioration to being ineffective or even toxic. The reasons for this controversy remain elusive. The ability of a root to retain K+ in the presence of NaCl was used as a physiological indicator to evaluate the ameliorative effects of PA. Pre-treatment with 1 mM Spm4+ (spermine), Spd3+ (spermidine) or Put2+ (putrescine) prevented salt-induced K+ leak only in the mature root zone of hydroponically grown maize and Arabidopsis. In contrast, in the distal... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350126 Wed, 10 Mar 2010 06:01:15 +0100 3350126 http://www.medworm.com/index.php?rid=3350125&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F408%3Frss%3D1 Protein phosphorylation is crucial in the signaling of guard cells in response to various factors, including light, ABA and CO2, and calcium plays a central role in these signaling processes. Despite extensive studies on the functional role of Ca2+-regulated protein kinases in plants, relatively little is known about the biochemical properties of the kinases in guard cells. To investigate this, we isolated the VfCIPK1 [Vicia faba calcineurin B-like calcium-binding protein (CBL)-interacting protein kinase 1] cDNA from guard cells of Vicia faba L., which encodes a Ca2+-regulated protein kinase that belongs to the SnRK3 subgroup, and characterized VfCIPK1 at the biochemical level. VfCIPK1 genes were expressed in guard cells and roots, but not in mesophyll cells. The VfCIPK1 protein was locali... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350125 Wed, 10 Mar 2010 06:01:15 +0100 3350125 http://www.medworm.com/index.php?rid=3350124&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F395%3Frss%3D1 Late embryogenesis-abundant (LEA) proteins, accumulating to a high level during the late stages of seed development, may play a role as osmoprotectants. However, the functions and mechanisms of LEA proteins remained to be elucidated. Five major groups of LEA proteins have been described. In the present study, we report on the characterization of two members of soybean LEA IV proteins, basic GmPM1 and acidic GmPM28, by circular dichroism and Fourier transform infrared spectroscopy. The spectra of both proteins revealed limited defined secondary structures in the fully hydrated state. Thus, the soybean LEA IV proteins are members of ‘natively unfolded proteins’. GmPM1 or GmPM28 proteins showed a conformational change under hydrophobic or dry conditions. After fast or slow drying,... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350124 Wed, 10 Mar 2010 06:01:15 +0100 3350124 http://www.medworm.com/index.php?rid=3350123&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F380%3Frss%3D1 In Arabidopsis thaliana, there exist many typical responses to low phosphate (LP) stress, such as inhibition of primary root elongation, proliferation of lateral roots and accumulation of anthocyanin in leaves. The physiological, genetic and molecular mechanisms of these developmental responses remain undefined. We have isolated a phosphorus starvation-insensitive (psi) mutant. The mutant shows impaired inhibition of primary root growth, reduction of root hair growth and reduction of anthocyanin accumulation compared with the wild-type (WT) plants under an LP level. CycB1;1::GUS (cyclin B1;1::β-glucuronidase) staining suggests that the mutant has a higher ability to maintain cell elongation and cell division than the WT. The genetic analysis and gene cloning indicate that psi is a new... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350123 Wed, 10 Mar 2010 06:01:15 +0100 3350123 http://www.medworm.com/index.php?rid=3350122&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F366%3Frss%3D1 We examined the capacity for binding to phosphatidylinositol phosphates (PtdInsPs), and found that PCaP2 interacts strongly with PtdIns(3,5)P2, PtdIns(4,5)P2 and PtdIns(3,4,5)P3, and weakly with PtdIns(3,4)P2. Furthermore, calmodulin was associated with PCaP2 in a Ca2+-dependent manner, and its association weakened the interaction of PCaP2 with PtdInsPs. These results indicate that PCaP2 is involved in intracellular signaling through interaction with PtdInsPs and calmodulin in growing root hairs. PCaP2 was previously reported as microtubule-associated protein-18. We discuss the physiological roles of PCaP2 in relation to microtubules in cells. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350122 Wed, 10 Mar 2010 06:01:15 +0100 3350122 http://www.medworm.com/index.php?rid=3350121&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F354%3Frss%3D1 Plant stomata limit both carbon dioxide uptake and water loss; hence, stomatal aperture is carefully set as the environment fluctuates. Aperture area is known to be regulated in part by ion transport, but few of the transporters have been characterized. Here we report that AtALMT12 (At4g17970), a homolog of the aluminum-activated malate transporter (ALMT) of wheat, is expressed in guard cells of Arabidopsis thaliana. Loss-of-function mutations in AtALMT12 impair stomatal closure induced by ABA, calcium and darkness, but do not abolish either the rapidly activated or the slowly activated anion currents previously identified as being important for stomatal closure. Expressed in Xenopus oocytes, AtALMT12 facilitates chloride and nitrate currents, but not those of organic solutes. Therefore, w... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350121 Wed, 10 Mar 2010 06:01:15 +0100 3350121 http://www.medworm.com/index.php?rid=3350120&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F3%2F341%3Frss%3D1 In arbuscular mycorrhizal (AM) symbiosis, host plants supply photosynthates to AM fungi and, in return, they receive inorganic nutrients such as phosphate from finely branched fungal arbuscules. Plant cortical cells envelope arbuscules with periarbuscular membranes that are continuous with the plant plasma membranes. We prepared transgenic rice (Oryza sativa) plants that express a fusion of green fluorescent protein with rice AM-inducible phosphate transporter, OsPT11–GFP, and grew them with AM fungi. The fluorescence of the fusion transporter was observed in the arbuscule branch domain, where active nutrient exchange seems to occur. In contrast, a signal was not detected around intracellular hyphal coils on colonization by either Glomus mosseae or Gigaspora rosea, making the differe... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3350120 Wed, 10 Mar 2010 06:01:15 +0100 3350120 http://www.medworm.com/index.php?rid=3246809&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F339%3Frss%3D1 (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246809 Sat, 06 Feb 2010 12:27:40 +0100 3246809 http://www.medworm.com/index.php?rid=3246808&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F333%3Frss%3D1 We isolated frizzy1 (fiz1), a novel dominant actin mutant from Arabidopsis. In the fiz1 mutant, Glu272 was substituted with lysine in the hydrophobic loop of ACT8, which is very important for the polymerization. Live imaging of actin filaments revealed that the fiz1 mutation induced fragmentation of actin filaments in a semi-dominant manner. In addition, the dynamics of Golgi stacks and mitochondria were disrupted by the fiz1 effects. From these results, it was strongly suggested that the fiz1 mutation had dominant-negative effects on actin polymerization, which causes defects in the functions of actin filaments such as organelle transport. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246808 Sat, 06 Feb 2010 12:27:40 +0100 3246808 http://www.medworm.com/index.php?rid=3246807&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F328%3Frss%3D1 To express a foreign gene in plants effectively, a good expression system is required. Here we describe the identification of a transcriptional terminator that supports increased levels of expression. The terminators of several Arabidopsis genes were examined in transfected Arabidopsis T87 protoplasts. The heat shock protein 18.2 (HSP) terminator was the most effective in supporting increased levels of expression. The HSP terminator increases mRNA levels of both transiently and stably expressed transgenes approximately 2-fold more than the NOS (nopaline synthase) terminator. When combined with the HSP terminator, a translational enhancer increased gene expression levels approximately 60- to 100-fold in transgenic plants. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246807 Sat, 06 Feb 2010 12:27:40 +0100 3246807 http://www.medworm.com/index.php?rid=3246806&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F323%3Frss%3D1 Boron (B) deprivation induces various responses in plant cells, some of which can be observed very early. However, it has been unknown what kind of signal is generated by the stress. We found that B deprivation induced the expression of stress-responsive genes within 1 h in suspension-cultured tobacco BY-2 cells. The induction was largely suppressed by withholding medium Ca2+ or by adding a Ca2+ channel blocker. Analysis using aequorin-expressing cells showed that B-deprived cells took up more Ca2+ than control cells. These results suggest that Ca2+ influx plays a role in B deprivation stress signaling. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246806 Sat, 06 Feb 2010 12:27:40 +0100 3246806 http://www.medworm.com/index.php?rid=3246805&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F312%3Frss%3D1 In the unicellular green alga Chlamydomonas reinhardtii, translation of the chloroplast-encoded psbA mRNA is regulated by the light-dependent binding of a nuclear-encoded protein complex (RB38, RB47, RB55 and RB60) to the 5'-untranslated region of the RNA. Despite the absence of any report identifying a red light photoreceptor within this alga, we show that the expression of the rb38, rb47 and rb60 genes, as well as the nuclear-encoded psbO gene that directs the synthesis of OEE1 (oxygen evolving enhancer 1), is differentially regulated by red light. Further elucidation of the signal transduction pathway shows that calmodulin is an important messenger in the signaling cascade that leads to the expression of rb38, rb60 and psbO, and that a chloroplast signal affects rb47 at the translationa... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246805 Sat, 06 Feb 2010 12:27:40 +0100 3246805 http://www.medworm.com/index.php?rid=3246804&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F302%3Frss%3D1 Abscisic acid (ABA) induces production of reactive oxygen species (ROS) and nitric oxide (NO), elevation of the cytosolic free calcium ion concentration ([Ca2+]cyt) and cytosolic pH (pHcyt), and activation of S-type anion channels in guard cells, causing stomatal closure. To investigate whether Arabidopsis Two pore channel 1 (AtTPC1) that encodes the slow vacuolar (SV) channel is involved in stomatal closure, we examined stomatal movements and mobilization of second messengers in the attpc1-2 loss-of-function mutant in response to ABA, methyl jasmonate (MeJA) and Ca2+. Both ABA and MeJA elicited production of ROS and NO, [Ca2+]cyt oscillations, cytosolic alkalization and activation of S-type anion channel currents to lead to stomatal closure in the attpc1-2 mutant as well as the wild type.... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246804 Sat, 06 Feb 2010 12:27:40 +0100 3246804 http://www.medworm.com/index.php?rid=3246803&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F294%3Frss%3D1 Cellulose synthesis in plants is believed to be carried out by the plasma membrane-associated rosette structure which can be observed by electron microscopy. Despite decade-long speculation, it had not been demonstrated whether the rosette is the site of catalytic activity of cellulose synthesis. To determine the relationship between this structure and cellulose synthesis, we successfully isolated detergent-insoluble rosettes from the plasma membrane of bean epicotyls. However, the purified rosettes did not possess cellulose synthesis activity in vitro. Conversely, detergent-soluble granular particles of ~9.5–10 nm diameter were also isolated and exhibited UDP-glucose binding activity and possessed β-1,4-glucan (cellulose) synthesis activity in vitro. The particle, ref... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246803 Sat, 06 Feb 2010 12:27:40 +0100 3246803 http://www.medworm.com/index.php?rid=3246802&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F282%3Frss%3D1 Carpel suppression is a trigger for sexual dimorphism in the dioecious plant Silene latifolia. To clarify what kind of genes are involved in carpel suppression in this species, we generated a bisexual mutant, R025, by C-ion beam irradiation. R025 produces bisexual flowers with a mature gynoecium and mature stamens. Genetic analysis of R025 attributed the bisexual trait to mutations on the Y chromosome. Scanning electron microscopy (SEM) analysis of early floral development revealed that the carpel size of R025 was different from that of wild-type males in spite of the male background in R025. We also identified an S. latifolia CLAVATA1-like gene (SlCLV1) as a candidate of the CLAVATA–WUSCHEL (CLV–WUS) pathway. Two separate pathways, the CLV–WUS pathway and the CUP-SHAPED ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246802 Sat, 06 Feb 2010 12:27:40 +0100 3246802 http://www.medworm.com/index.php?rid=3246801&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F271%3Frss%3D1 The d1 mutant, which is deficient for the heterotrimeric G-protein subunit (G) gene of rice, shows dwarfism and sets small round seeds. To determine whether dwarfism in d1 is due to a reduction in cell number or to shortened cell length, the cell number of the leaf sheath, the internode, the root and the lemma was compared between Nipponbare, a wild-type rice and d1-5, a d1 allele derived from Nipponbare. Our results indicate that the cell number was reduced in all organs analyzed in d1-5. In addition, cell enlargement was found in roots and lemma of d1-5, although the organ length in d1-5 was shorter than that of wild-type rice. These results suggest that rice G participates in cell proliferation in rice. Western blot analyses using anti-G antibody and RT–PCR analyses indicate that ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246801 Sat, 06 Feb 2010 12:27:40 +0100 3246801 http://www.medworm.com/index.php?rid=3246800&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F262%3Frss%3D1 The plant genome encodes a wide range of receptor-like proteins but the function of most of these proteins is unknown. We propose the use of affinity cross-linking of biotinylated ligands for a ligand-based survey of the corresponding receptor molecules. Biotinylated ligands not only enable the analysis of receptor–ligand interactions without the use of radioactive compounds but also the isolation and identification of receptor molecules by a simple affinity trapping method. We successfully applied this method for the characterization, isolation and identification of the chitin elicitor binding protein (CEBiP). A biocytin hydrazide conjugate of N-acetylchitooctaose (GN8-Bio) was synthesized and used for the detection of CEBiP in the plasma or microsomal membrane preparations from ric... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246800 Sat, 06 Feb 2010 12:27:40 +0100 3246800 http://www.medworm.com/index.php?rid=3246799&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F252%3Frss%3D1 Leaves possess intrinsic information about their final size, but the developmental mechanisms setting the limits of growth are not well characterized. By screening enhancer trap lines that show a specific expression pattern in leaf primordia, we isolated one line, 576. This line contains a T-DNA insertion upstream of the basic helix–loop–helix (bHLH) transcription factor SPATULA (SPT) gene, and shows expression in the basal region of young leaves, where cell proliferation is active. An spt loss-of-function mutation increased leaf size and total cell number within a leaf, while SPT overexpression decreased leaf size and total cell number within a leaf. Although spt mutations did not affect cell size, SPT overexpression decreased the cell size in fully expanded leaves. Genetic an... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246799 Sat, 06 Feb 2010 12:27:40 +0100 3246799 http://www.medworm.com/index.php?rid=3246798&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F239%3Frss%3D1 The stress phytohormone ABA inhibits the developmental transition taking the mature embryo in the dry seed towards a young seedling. ABA also induces the accumulation of the basic leucine zipper (bZIP) transcription factor ABA-insensitive 5 (ABI5) which, apart from blocking endosperm rupture, also protects the embryo by stimulating the expression of late embryogenesis abundant (LEA) genes that conferred osmotolerance during seed maturation. It is unknown whether ABA recruits additional embryonic pathways to control early seedling growth and fitness. Here we identify gia3 (growth insensitive to ABA3), a recessive locus in Arabidopsis mediating cotyledon cellular maturation and ABA-dependent repression of cotyledon expansion and greening. Microarray studies showed that expression of the esse... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246798 Sat, 06 Feb 2010 12:27:40 +0100 3246798 http://www.medworm.com/index.php?rid=3246797&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F225%3Frss%3D1 In this study, we produced selective images of photosystems in plant chloroplasts in situ. We used a spectroimaging microscope, equipped with a near-infrared (NIR) laser that provided light at wavelengths mainly between 800 and 830 nm, to analyze chlorophyll autofluorescence spectra and images from chloroplasts in leaves of Zea mays at room temperature. Femtosecond laser excitation of chloroplasts in mesophyll cells revealed a spectral shape that was attributable to PSII and its antenna in the centers of grana spots. We found that a continuous wave emitted by the NIR laser at a wavelength as long as 820 nm induced chlorophyll autofluorescence with a high contribution from PSI through a one-photon absorption mechanism. A spectral shape attributable to PSI and its antenna was thus obtained u... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246797 Sat, 06 Feb 2010 12:27:40 +0100 3246797 http://www.medworm.com/index.php?rid=3246796&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F215%3Frss%3D1 Flowers of tulip cv. ‘Murasakizuisho’ have a purple perianth except for the bottom region, which is blue in color even though it has the same anthocyanin, delphinidin 3-O-rutinoside, as the entire perianth. The development of the blue coloration in the perianth bottom is due to complexation by anthocyanin, flavonol and iron (Fe), as well as a vacuolar iron transporter, TgVit1. Although transient expression of TgVit1 in the purple cells led to a color change to light blue, the coloration of the transformed cells did not coincide with the dark blue color of the cells of the perianth bottom. We thought that another factor is required for the blue coloration of the cells of perianth bottom. To examine the effect of ferritin (FER), an Fe storage protein, on blue color development, w... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246796 Sat, 06 Feb 2010 12:27:40 +0100 3246796 http://www.medworm.com/index.php?rid=3246795&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F201%3Frss%3D1 Chemically induced non-nodulating nod139 and nn5 mutants of soybean (Glycine max) show no visible symptoms in response to rhizobial inoculation. Both exhibit recessive Mendelian inheritance suggesting loss of function. By allele determination and genetic complementation in nod139 and nn5, two highly related lipo-oligochitin LysM-type receptor kinase genes in Glycine max were cloned; they are presumed to be the critical nodulation-inducing (Nod) factor receptor similar to those of Lotus japonicus, pea and Medicago truncatula. These duplicated receptor genes were called GmNFR5 and GmNFR5β. Nonsense mutations in GmNFR5 and GmNFR5β were genetically complemented by both wild-type GmNFR5 and GmNFR5β in transgenic roots, indicating that both genes are functional. Both genes lack in... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246795 Sat, 06 Feb 2010 12:27:40 +0100 3246795 http://www.medworm.com/index.php?rid=3246794&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F190%3Frss%3D1 Though two types of chloroplastic ascorbate peroxidase (APX) located in the thylakoid membrane (tAPX) and stroma (sAPX) have been thought to be key regulators of intracellular levels of H2O2, their physiological significance in the response to photooxidative stress is still under discussion. Here we characterized single mutants lacking either tAPX (KO-tAPX) or sAPX (KO-sAPX). Under exposure to high light or treatment with methylviologen under light, H2O2 and oxidized proteins accumulated to higher levels in both mutant plants than in the wild-type plants. On the other hand, the absence of sAPX and tAPX drastically suppressed the expression of H2O2-responsive genes under photooxidative stress. Interestingly, the most marked effect of photooxidative stress on the accumulation of H2O2 and oxi... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246794 Sat, 06 Feb 2010 12:27:40 +0100 3246794 http://www.medworm.com/index.php?rid=3246793&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F2%2F177%3Frss%3D1 Plant fertilization is achieved through the involvement of various pollen–pistil interactions. Self-/non-self-recognition in pollination is important to avoid inbreeding, and directional and sustainable control of pollen tube growth is critical for the pollen tube to deliver male germ cells. Recently, various secreted peptides (polypeptides) have been reported to be involved in cell–cell communication of pollen–pistil interactions. These include determinants of self-incompatibility, factors for pollen germination and tube growth, and pollen tube attractants. Interestingly, many of them are cysteine-rich peptides/polypeptides (CRPs). In this review, I focus on the peptides involved in pollen–pistil interactions and discuss properties of peptide signaling in each step... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3246793 Sat, 06 Feb 2010 12:27:40 +0100 3246793 http://www.medworm.com/index.php?rid=3175695&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F164%3Frss%3D1 Two mutations in Arabidopsis thaliana, auxin response factor6 (arf6) and arf8, concomitantly delayed the elongation of floral organs and subsequently delayed the opening of flower buds. This phenotype is shared with the jasmonic acid (JA)-deficient mutant dad1, and, indeed, the JA level of arf6 arf8 flower buds was decreased. Among JA biosynthetic genes, the expression level of DAD1 (DEFECTIVE IN ANTHER DEHISCENCE1) was markedly decreased in the double mutant, suggesting that ARF6 and ARF8 are required for activation of DAD1 expression. The double mutant arf6 arf8 also showed other developmental defects in flowers, such as aberrant vascular patterning and lack of epidermal cell differentiation in petals. We found that class 1 KNOX genes were expressed ectopically in the developing floral o... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175695 Fri, 15 Jan 2010 11:58:17 +0100 3175695 http://www.medworm.com/index.php?rid=3175694&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F144%3Frss%3D1 As a step toward a comprehensive description of lignin biosynthesis in Populus trichocarpa, we identified from the genome sequence 95 phenylpropanoid gene models in 10 protein families encoding enzymes for monolignol biosynthesis. Transcript abundance was determined for all 95 genes in xylem, leaf, shoot and phloem using quantitative real-time PCR (qRT-PCR). We identified 23 genes that most probably encode monolignol biosynthesis enzymes during wood formation. Transcripts for 18 of the 23 are abundant and specific to differentiating xylem. We found evidence suggesting functional redundancy at the transcript level for phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate:CoA ligase (4CL), p-hydroxycinnamoyl-CoA:quinate shikimate p-hydroxycinnamoyltransferase (HCT), c... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175694 Fri, 15 Jan 2010 11:58:17 +0100 3175694 http://www.medworm.com/index.php?rid=3175693&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F132%3Frss%3D1 Three β-glucosidases (At1g66270-BGLU21, At1g66280-BGLU22, and At3g09260-BGLU23) were purified from the roots of Arabidopsis and their cDNAs were expressed in insect cells. In addition, two β-glucosidase binding protein cDNAs (At3g16420; PBPI and At3g16430; PBPII) were expressed in Escherichia coli and their protein products purified. These binding proteins interact with β-glucosidases and activate them. BGLU21, 22 and 23 hydrolyzed the natural substrate scopolin specifically and also hydrolyzed to some extent substrates whose aglycone moiety is similar to scopolin (e.g. esculin and 4-MU-glucoside). In contrast, they hydrolyzed poorly DIMBOA-glucoside and did not hydrolyze pNP- and oNP-glucosides. We determined the physicochemical properties of native and recombinant BGLUs, a... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175693 Fri, 15 Jan 2010 11:58:17 +0100 3175693 http://www.medworm.com/index.php?rid=3175692&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F123%3Frss%3D1 Cutinase is an esterase that degrades the polyester cutin, a major component of the plant cuticle. Although cutinase activity has been detected in pollen, the genes encoding this enzyme have not been identified. Here, we report the identification and characterization of Arabidopsis CDEF1 (cuticle destructing factor 1), a novel candidate gene encoding cutinase. CDEF1 encodes a member of the GDSL lipase/esterase family of proteins, although fungal and bacterial cutinases belong to the /β hydrolase superfamily which is different from the GDSL lipase/esterase family. According to the AtGenExpress microarray data, CDEF1 is predominantly expressed in pollen. The ectopic expression of CDEF1 driven by the 35S promoter caused fusion of organs, including leaves, stems and flowers, and increased... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175692 Fri, 15 Jan 2010 11:58:17 +0100 3175692 http://www.medworm.com/index.php?rid=3175691&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F114%3Frss%3D1 In conclusion, differences in transport activity between OsSUT1 and OsSUT5 indicate that type II SUTs have a range of transport activities that are tuned to their function in the plant. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175691 Fri, 15 Jan 2010 11:58:17 +0100 3175691 http://www.medworm.com/index.php?rid=3175690&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F103%3Frss%3D1 The post-translational conjugation of small ubiquitin-related modifiers (SUMOs) to other proteins is involved in regulation of many processes in eukaryotic development; although its role in plant development is beginning to be dissected. Previously, we demonstrated that the siz1 mutant, which is impaired in SUMO E3 ligase, showed a dwarf-like shoot phenotype with accumulation of salicylic acid (SA), and the expression of nahG, a bacterial salicylate hydroxylase that catabolizes SA, in siz1 reduced the SA level and suppressed dwarfism. Herein, we provide evidence that the SIZ1 gene controls cell division and elongation through regulation of the SA level. Mature siz1-2 and siz1-3 plants exhibited a dwarf-like shoot phenotype that is attributable to decreased leaf cell volume and number relat... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175690 Fri, 15 Jan 2010 11:58:17 +0100 3175690 http://www.medworm.com/index.php?rid=3175689&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F91%3Frss%3D1 In this study we report the first direct and unequivocal identification of a natural Fe complex in plant xylem sap. A tri-Fe(III), tri-citrate complex (Fe3Cit3) was found in the xylem sap of Fe-deficient tomato (Solanum lycopersicum Mill. cv. ‘Tres Cantos’) resupplied with Fe, by using an integrated mass spectrometry approach based on exact molecular mass, isotopic signature and Fe determination and retention time. This complex has been modeled as having an oxo-bridged tri-Fe core. A second complex, a di-Fe(III), di-citrate complex was also detected in Fe–citrate standards along with Fe3Cit3, with the allocation of Fe between the two complexes depending on the Fe to citrate ratio. These results provide evidence for Fe–citrate complex xylem transport in plants. The c... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175689 Fri, 15 Jan 2010 11:58:17 +0100 3175689 http://www.medworm.com/index.php?rid=3175688&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F80%3Frss%3D1 The molecular basis underlying the development, maintenance and function of companion cells in plants is largely unknown. The identification of several genes expressed specifically in companion cells implies the contribution of specific transcriptional elements to the identity of companion cells. However, less is known about the companion cell-specific transcriptional regulation of promoters. We established a novel assay method using gene-gun delivery of partially deleted promoters to string-containing vascular bundles excised from the petiole of Brassica napus for the rapid identification of cis-elements. To test this system, we analyzed the Arabidopsis METALLOTHIONEIN 2B (MT2B) gene, which is expressed in companion cells. The assay revealed a 49-bp region possessing two predicted cis-reg... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175688 Fri, 15 Jan 2010 11:58:17 +0100 3175688 http://www.medworm.com/index.php?rid=3175687&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F68%3Frss%3D1 This study expands the knowledge of high-affinity Na+ uptake in land plants for both uptake characteristics and involvement of HKT transporters. In non-flowering plants, we analyzed the Na+ content of wild mosses, carried out experiments on K+ and Na+ uptake in the micromolar range of concentrations with the moss Physcomitrella patens and the liverwort Riccia fluitans, studied a hkt1 mutant of P. patens and identified the HKT genes of the lycopodiophyta (clubmoss) Selaginella moellendorffii. In flowering plants we studied Na+ uptake in the micromolar range of concentrations in 16 crop plant species, identified the HKT transporters that could mediate high-affinity Na+ uptake in several species of the Triticeae tribe, and described some characteristics of high-affinity Na+ uptake in other sp... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175687 Fri, 15 Jan 2010 11:58:17 +0100 3175687 http://www.medworm.com/index.php?rid=3175686&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F58%3Frss%3D1 An endogenous double-stranded RNA (dsRNA), which has recently been recognized as the dsRNA virus Oryza sativa endornavirus (OsEV), is found in many strains of cultivated rice (Oryza sativa). Small RNAs derived from OsEV dsRNA were detected, indicating that the RNA silencing machinery recognizes OsEV dsRNA. The existence of OsEV in knock-down (KD) lines of five genes of RNA-dependent RNA polymerase (OsRDR1–OsRDR5) or two genes of Dicer-like protein (OsDCL2 or OsDCL3a) was examined to characterize the relationship between the host RNA silencing system and the propagation of this dsRNA virus. OsEV was not detected in OsRDR4-KD or OsDCL2-KD T1 lines. We attempted to introduce OsEV into these KD lines by crossing them with OsEV-carrying plants because of the efficient transmission of OsEV... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175686 Fri, 15 Jan 2010 11:58:17 +0100 3175686 http://www.medworm.com/index.php?rid=3175685&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F47%3Frss%3D1 In rice panicle development, new meristems are generated sequentially in an organized manner and acquire their identity in a time- and position-dependent manner. In the panicle of the panicle phytomer2-1 (pap2-1) mutant, the pattern of meristem initiation is disorganized and newly formed meristems show reduced competency to become spikelet meristems, resulting in the transformation of early arising spikelets into rachis branches. In addition, rudimentary glumes and sterile lemmas, the outermost organs of the spikelet, elongate into a leafy morphology. We propose that PAP2 is a positive regulator of spikelet meristem identity. Map-based cloning revealed that PAP2 encodes OsMADS34, a member of the SEPALLATA (SEP) subfamily of MADS-box proteins. PAP2/OsMADS34 belongs to the LOFSEP subgroup of... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175685 Fri, 15 Jan 2010 11:58:17 +0100 3175685 http://www.medworm.com/index.php?rid=3175684&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F38%3Frss%3D1 In conclusion, VPE plays an important role in the formation of protein crystalline structures in PSVs. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175684 Fri, 15 Jan 2010 11:58:17 +0100 3175684 http://www.medworm.com/index.php?rid=3175683&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F21%3Frss%3D1 Waterlogging stress causes yield reduction in cotton (Gossypium hirsutum L.). A major component of waterlogging stress is the lack of oxygen available to submerged tissues. While changes in expressed protein, gene transcription and metabolite levels have been studied in response to low oxygen stress, little research has been done on molecular responses to waterlogging in cotton. We assessed cotton growth responses to waterlogging and assayed global gene transcription responses in root and leaf cotton tissues of partially submerged plants. Waterlogging caused significant reductions in stem elongation, shoot mass, root mass and leaf number, and altered the expression of 1,012 genes (4% of genes assayed) in root tissue as early as 4 h after flooding. Many of these genes were associated with c... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175683 Fri, 15 Jan 2010 11:58:17 +0100 3175683 http://www.medworm.com/index.php?rid=3175682&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F9%3Frss%3D1 In this study, we evaluated the effects of AtBI-1 overexpression on the rice metabolome in response to oxidative stress. AtBI-1-overexpressing rice cells in suspension displayed enhanced tolerance to menadione-induced oxidative stress compared with vector control cells, whereas AtBI-1 overexpression did not influence the increase of intracellular H2O2 concentration or inhibition of oxidative stress-sensitive aconitase activity. Capillary electrophoresis–mass spectrometry (CE-MS)-based metabolome analysis revealed dynamic metabolic changes in oxidatively stressed rice cells, e.g. depletion of the central metabolic pathway, imbalance of the redox state and energy charge, and accumulation of amino acids. Furthermore, comparative metabolome analysis demonstrated that AtBI-1 overexpressio... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175682 Fri, 15 Jan 2010 11:58:17 +0100 3175682 http://www.medworm.com/index.php?rid=3175681&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F51%2F1%2F1%3Frss%3D1 Stomata are composed of a pair of guard cells and a pore between them, and their density and positions are regulated by developmental and environmental signals. In a screen in which we overexpressed many genes coding for putative secretory proteins one by one in Arabidopsis, we identified a gene named STOMAGEN, which increases stomatal density when overexpressed. The STOMAGEN gene encodes a small peptide with a putative secretory signal sequence at its N-terminus and is expressed preferentially in mesophyll cells. This peptide belongs to the EPIDERMAL PATTERNING FACTOR (EPF) family of the cysteine-rich peptides superfamily. The mature form was a 45-amino-acid peptide (stomagen) with three intramolecular disulfide bonds. Stomagen treatment at very low concentrations, as low as 10 nM, increa... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3175681 Fri, 15 Jan 2010 11:58:17 +0100 3175681 http://www.medworm.com/index.php?rid=3084597&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2234%3Frss%3D1 Zinc (Zn) is an essential micronutrient for various physiological and metabolic processes in plants, although it is toxic in excess. To understand better Zn-responsive proteins, we developed a highly improved method of isoelectric focusing (IEF) in which whole lysate from Arabidopsis roots is subjected to IEF without any desalting steps. In this method, samples extracted with lysis buffer containing 1.5% SDS can also be directly applied to IEF. By applying this method to Zn-treated Arabidopsis roots, 10 up-regulated and 17 down-regulated proteins were identified, 15 of which showed a significant correlation with previously reported transcriptomic data. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084597 Mon, 14 Dec 2009 15:28:35 +0100 3084597 http://www.medworm.com/index.php?rid=3084596&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2223%3Frss%3D1 Accumulation of Cd in rice grain is a serious concern of food safety since rice as a staple food is a major source of Cd intake in Asian countries. However, the mechanisms controlling Cd accumulation in rice are still poorly understood. Herein, we report both physiological and genetic analysis of two rice cultivars contrasting in Cd accumulation, which were screened from a core collection of rice cultivars. The cultivar Anjana Dhan (Indica) accumulated much higher levels of Cd than Nipponbare (Japonica) in the shoots and grains when grown in both soil and solution culture. A short-term uptake experiment (20 min) showed that Cd uptake by Nipponbare was higher than that by Anjana Dhan. However, the concentration of Cd in the shoot and xylem sap was much higher in Anjana Dhan than in Nipponba... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084596 Mon, 14 Dec 2009 15:28:35 +0100 3084596 http://www.medworm.com/index.php?rid=3084595&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2210%3Frss%3D1 We have isolated a combination of high-light and heat-shock (HL + HS) stress-inducible genes, including a NAC transcription factor designated ANAC078. Here we explored the physiological function of ANAC078 under HL stress. Yeast transcription activity assays showed that ANAC078 functions as a transcriptional activator. A fusion protein composed of green fluorescent protein (GFP) and full-length ANAC078 was detected in the nucleus and cytoplasm, while fusion proteins comprising GFP and ANAC078 deleted of a putative transmembrane motif were found only in the nucleus. In ANAC078-overexpressing Arabidopsis plants (Ox-ANAC078-43), the transcription of 166 genes was up-regulated compared with the levels in wild-type plants under HL (1200 µmol m–2 s–1, 30°C). These genes inc... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084595 Mon, 14 Dec 2009 15:28:35 +0100 3084595 http://www.medworm.com/index.php?rid=3084594&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2200%3Frss%3D1 Lignans are a large class of secondary metabolites in plants, with numerous biological effects in mammals, including antitumor and antioxidant activities. Sesamin, the most abundant furofuran-class lignan in sesame seeds (Sesamum plants), is produced by the cytochrome P450 enzyme CYP81Q1 from the precursor lignan, pinoresinol. In contrast, Forsythia plants produce dibenzylbutyrolactone-class lignans, such as matairesinol, from pinoresinol via the catalysis of pinoresinol/lariciresinol reductase (PLR) and secoisolariciresinol dehydrogenase. Here we present the engineering of lignan biosynthesis in Forsythia cell suspension cultures for the development of an efficient production method of beneficial lignans. A suspension cell culture prepared from leaves of Forsythia koreana produced lignans... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084594 Mon, 14 Dec 2009 15:28:35 +0100 3084594 http://www.medworm.com/index.php?rid=3084593&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2183%3Frss%3D1 We investigated the role of polyamines (PAs) in lima bean (Phaseolus lunatus) leaves on the production of herbivorous mite (Tetranychus urticae)-induced plant volatiles that attract carnivorous natural enemies of the herbivores. To do this, we focused on the effects of the exogenous PAs [cadaverine, putrescine, spermidine and spermine (Spm)] on the production of volatiles, H2O2 and jasmonic acid (JA) and the levels of defensive genes, cytosolic calcium and reactive oxygen species (ROS). Among the tested PAs, Spm was the most active in inducing the production of volatile terpenoids known to be induced by T. urticae. An increase in JA levels was also found after Spm treatment, indicating that Spm induces the biosynthesis of JA, which has been shown elsewhere to regulate the production of som... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084593 Mon, 14 Dec 2009 15:28:35 +0100 3084593 http://www.medworm.com/index.php?rid=3084592&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2174%3Frss%3D1 In chloroplasts, several water-soluble carbohydrates have been suggested to act as stress protectants. The trisaccharide raffinose (-1,6-galactosyl sucrose) is such a carbohydrate but has received little attention. We here demonstrate by compartmentation analysis of leaf mesophyll protoplasts that raffinose is clearly (to about 20%) present in chloroplasts of cold-treated common bugle (Ajuga reptans L.), spinach (Spinacia oleracea L.) and Arabidopsis [Arabidopsis thaliana (L.) Heynh.] plants. The two dedicated enzymes needed for raffinose synthesis, galactinol synthase and raffinose synthase, were found to be extra-chloroplastic (probably cytosolic) in location, suggesting that the chloroplast envelope contains a raffinose transporter. Uptake experiments with isolated Ajuga and Arabidopsis... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084592 Mon, 14 Dec 2009 15:28:35 +0100 3084592 http://www.medworm.com/index.php?rid=3084591&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2162%3Frss%3D1 In an effort to elucidate biological functions of transcription factors of Brassica rapa L. (ssp. pekinensis), an NGATHA homolog, BrNGA1, that belongs to the B3-type transcription factor superfamily was identified and expressed in Arabidopsis thaliana under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Arabidopsis plants overexpressing BrNGA1, named BrNGA1ox, displayed markedly reduced organ growth compared with the wild type: lateral organs, such as leaves, flowers and cotyledons, were small and distinctively narrow, and their root growth was also severely retarded. Reduced sizes of BrNGA1ox organs were mainly due to reduction in cell numbers. Kinematic analysis of leaf growth revealed that both the rate and duration of cell proliferation declined during organogenesis, ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084591 Mon, 14 Dec 2009 15:28:35 +0100 3084591 http://www.medworm.com/index.php?rid=3084590&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2146%3Frss%3D1 Amorpha-4,11-diene synthase (ADS) of Artemisia annua catalyzes the conversion of farnesyl diphosphate into amorpha-4,11-diene, the first committed step in the biosynthesis of the antimalarial drug artemisinin. The promoters of ADS contain two reverse-oriented TTGACC W-box cis-acting elements, which are the proposed binding sites of WRKY transcription factors. A full-length cDNA (AaWRKY1) was isolated from a cDNA library of the glandular secretory trichomes (GSTs) in which artemisinin is synthesized and sequestered. AaWRKY1 encodes a 311 amino acid protein containing a single WRKY domain. AaWRKY1 and ADS genes were highly expressed in GSTs and both were strongly induced by methyl jasmonate and chitosan. Transient expression analysis of the AaWRKY1–GFP (green fluorescent protein) repor... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084590 Mon, 14 Dec 2009 15:28:35 +0100 3084590 http://www.medworm.com/index.php?rid=3084589&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2133%3Frss%3D1 Lateral organ traits in higher plants, such as lamina shape and trichome distribution, change gradually in association with shoot maturation. Regulation of this shoot maturation process in the vegetative phase has been extensively investigated, and members of the SQUAMOSA PROMOTER BINDING PROTEIN (SBP)-box family of transcription factors have been shown to be involved in this process. However, little is known about the regulation of shoot maturation in the reproductive phase. We analyzed SPL10, SPL11 and SPL2, which are closely related members of the SBP-box family in Arabidopsis. While cauline leaves had oblong lamina and few trichomes emerged on cauline leaves and flowers in wild-type plants, transgenic plants expressing a dominant repressor version of SPL10/11/2 had wide cauline leaves ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084589 Mon, 14 Dec 2009 15:28:35 +0100 3084589 http://www.medworm.com/index.php?rid=3084588&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2123%3Frss%3D1 Responses to water stress are thought to be mediated by transcriptional regulation of gene expression via reversible protein phosphorylation events. Previously, we reported that bZIP (basic-domain leucine zipper)-type AREB/ABF (ABA-responsive element-binding protein/factor) transcription factors are involved in ABA signaling under water stress conditions in Arabidopsis. The AREB1 protein is phosphorylated in vitro by ABA-activated SNF1-related protein kinase 2s (SnRK2s) such as SRK2D/SnRK2.2, SRK2E/SnRK2.6 and SRK2I/SnRK2.3 (SRK2D/E/I). Consistent with this, we now show that SRK2D/E/I and AREB1 co-localize and interact in nuclei in planta. Our results show that unlike srk2d, srk2e and srk2i single and double mutants, srk2d srk2e srk2i (srk2d/e/i) triple mutants exhibit greatly reduced tole... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084588 Mon, 14 Dec 2009 15:28:35 +0100 3084588 http://www.medworm.com/index.php?rid=3084587&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2112%3Frss%3D1 In this study, we characterized the increased SA-sensitive phenotype of this mutant in detail and addressed its relationship with ABA-related and dwarf phenotypes. We found that the ahg2-1 mutant had a high endogenous SA level and an elevated resistance to bacterial pathogens. Double mutant analyses showed that Arabidopsis plants defective in the SA signaling pathway (npr1 and pad4 mutants and nahG transgenic plants) could suppress neither the ABA hypersensitivity nor the dwarf phenotypes. These results indicate that ABA-related, SA-related and dwarf phenotypes of the ahg2-1 mutant are independent of each other. To obtain more insight into the molecular basis of the effect of ahg2-1, microarray analyses were conducted not only for ahg2-1 but also for ahg2sid2 or ahg2abi1 so as to reduce th... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084587 Mon, 14 Dec 2009 15:28:35 +0100 3084587 http://www.medworm.com/index.php?rid=3084586&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2092%3Frss%3D1 In this study, changes in phenotype, physiology and gene expression of three-leaf-old seedlings of HZ4 and C7-2 under the conditions of progressive water deficit (WD) and re-watering (RW) were compared to gain knowledge for breeding new maize foundation genotypes with higher drought tolerance. Progressive WD was produced by adding polyethylene glycol (PEG 6000) at 24 h intervals (24, 48 and 72 h) in Hoagland’s nutrient solution, resulting in water potentials of –0.15, –0.3 and –0.5 MPa. The seedlings treated for 24 h at –0.3 MPa were subjected to RW in the solution without complementation with PEG. The results showed that C7-2 seedlings are more tolerant to progressive WD than HZ4 seedlings in part because the former have a larger stomatal resistance, a relati... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084586 Mon, 14 Dec 2009 15:28:35 +0100 3084586 http://www.medworm.com/index.php?rid=3084585&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2084%3Frss%3D1 We investigated the role of membrane fatty acids in basal proton leaks and uncoupling protein (UCP)-dependent proton conductance in Arabidopsis mitochondria. Using wild-type cells, cold-sensitive fad2 mutant cells, deficient in -6-oleate desaturase, and cold-tolerant FAD3+ transformant cells, overexpressing -3-linoleate desaturase, we showed that basal proton leak in the non-phosphorylating state was dependent on lipid composition. The extent of membrane proton leak was drastically reduced in the fad2 mutant, containing low amounts of polyunsaturated fatty acids. Conversely, this proton leak was higher in FAD3+ mitochondria that exhibit a higher polyunsaturated fatty acid content and high protein to lipid ratio. The dependency of membrane leaks upon membrane potential was higher in FAD3+ a... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084585 Mon, 14 Dec 2009 15:28:35 +0100 3084585 http://www.medworm.com/index.php?rid=3084584&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2069%3Frss%3D1 In this study, the formation of white sectors was temporally investigated in the Arabidopsis leaf-variegated mutant var2. Green sectors were found to emerge from white sectors after the formation of the first true leaf. Transmission electron microscopic examination of plastid ultrastructures confirmed that the peripheral zone in the var2 shoot meristem contained proplastids but lacked developing chloroplasts that were normally detected in wild type. These data suggest that chloroplast development proceeds very slowly in var2 variegated leaves. A notable feature in var2 is that the plastids in white sectors contain remarkable globular vacuolated membranes and prolamellar body-like structures. Although defective plastids were hardly observed in shoot meristems, they began to accumulate durin... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084584 Mon, 14 Dec 2009 15:28:35 +0100 3084584 http://www.medworm.com/index.php?rid=3084583&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2057%3Frss%3D1 The Arabidopsis zigzgag (zig) is a loss-of-function mutant of Qb-SNARE VTI11 which is involved in vesicle trafficking between the trans-Golgi network (TGN) and vacuoles. zig-1 exhibits abnormality in both shoot gravitropism and morphology. To elucidate the molecular network of the post-Golgi membrane trafficking in plant cells, we have isolated the suppressor mutants of zig. Here we report zig suppressor 2 (zip2) and zip4 that are recessive mutants and partially suppress abnormality in both gravitropism and morphology. ZIP2 encodes AtVPS41/AtVAM2 protein that is thought to be an Arabidopsis ortholog of yeast Vps41p/Vam2p, which is involved in protein sorting to vacuoles as a subunit of the tethering complex HOPS. Yeast Vps41p is also proposed to function in budding of adaptor protein (AP)-... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084583 Mon, 14 Dec 2009 15:28:35 +0100 3084583 http://www.medworm.com/index.php?rid=3084582&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2047%3Frss%3D1 In the moss Physcomitrella patens, 10 Mur genes involved in peptidoglycan biosynthesis were found, and the MurE and Pbp genes are related to plastid division. Although the MraY and MurG genes were missing in our previous expressed sequence tag screening, they were discovered in the P. patens genome in this study, indicating that P. patens has a full set of genes capable of synthesizing peptidoglycan. In addition, a second MurA gene (PpMurA2) was found. Whereas Northern analyses indicated that PpMurA1, PpMurG and PpMraY were expressed, transcripts of PpMurA2 were detected only when RT–PCR was employed. Whereas GFP fusion proteins with either PpMurA1 or PpMraY were detected in chloroplasts, the PpMurA2 fusion proteins were located in the cytoplasm. Protonema cells in the wild-type plan... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084582 Mon, 14 Dec 2009 15:28:35 +0100 3084582 http://www.medworm.com/index.php?rid=3084581&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2034%3Frss%3D1 Peroxisome biogenesis factor 10 (PEX10) is a component of the peroxisomal matrix protein import machinery. To analyze the physiological function of PEX10, we used transgenic AtPEX10i Arabidopsis plants that had suppressed expression of the PEX10 gene due to RNA interference. AtPEX10i plants had patches of paleness on leaves, and abnormal floral organs that were typical of cuticular wax-deficient mutants. Quantitative analysis of cuticular wax revealed that the amount of wax in AtPEX10i plants was indeed lower than that in control plants. This result was confirmed by toluidine blue staining and scanning electron microscopic analysis of AtPEX10i. The CER1, CER4, WAX2 and SHN1 genes are known to be responsible for wax biosynthesis in Arabidopsis. Of these, CER1, CER4 and WAX2 were found to be... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084581 Mon, 14 Dec 2009 15:28:35 +0100 3084581 http://www.medworm.com/index.php?rid=3084580&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2023%3Frss%3D1 The intracellular membrane dynamics of Arabidopsis cells under high salt treatment were investigated. When Arabidopsis was treated with high levels of NaCl in hydroponic culture, root tip cells showed rapid changes in the vacuolar volume, a decrease in the number of small acid compartments, active movement of vesicles and accumulation of Na+ both in the central vacuole and in the vesicles around the main vacuole observed with the Na+-dependent fluorescence of Sodium Green. Detailed observation of Arabidopsis suspension-cultured cells under high salt treatment showed a similar pattern of response to that observed in root tip cells. Immunostaining of suspension-cultured cells with antibodies against AtNHX1 clearly showed the occurrence of dotted fluorescence in the cytoplasm only under salt ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084580 Mon, 14 Dec 2009 15:28:34 +0100 3084580 http://www.medworm.com/index.php?rid=3084579&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2015%3Frss%3D1 Although fluorescence microscopy screening has proven useful in the identification of genes involved in plant organelle biogenesis and integrity, the quantitative and statistical study of the geometric phenotype is highly limited. This situation could generate unconscious bias in the understanding and presentation of a mutant phenotype. Therefore, we have developed an automated quantification system for green fluorescent protein (GFP) images, which enabled us to easily obtain quantitative data on ER bodies (an endoplasmic reticulum-derived organelle). We isolated an ER body morphology mutant of Arabidopsis thaliana, leb-1 (long ER body). The leb-1 mutant had significantly fewer and larger ER bodies than the wild-type. An amino acid substitution of Cys29 with tyrosine (C29Y) on PYK10, a maj... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084579 Mon, 14 Dec 2009 15:28:34 +0100 3084579 http://www.medworm.com/index.php?rid=3084578&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F2000%3Frss%3D1 Organelle dynamics vary dramatically depending on cell type, developmental stage and environmental stimuli, so that various parameters, such as size, number and behavior, are required for the description of the dynamics of each organelle. Imaging techniques are superior to other techniques for describing organelle dynamics because these parameters are visually exhibited. Therefore, as the results can be seen immediately, investigators can more easily grasp organelle dynamics. At present, imaging techniques are emerging as fundamental tools in plant organelle research, and the development of new methodologies to visualize organelles and the improvement of analytical tools and equipment have allowed the large-scale generation of image and movie data. Accordingly, image databases that accumul... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084578 Mon, 14 Dec 2009 15:28:34 +0100 3084578 http://www.medworm.com/index.php?rid=3084577&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F12%2F1995%3Frss%3D1 (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=3084577 Mon, 14 Dec 2009 15:28:34 +0100 3084577 http://www.medworm.com/index.php?rid=2980927&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1994%3Frss%3D1 (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980927 Wed, 11 Nov 2009 15:54:39 +0100 2980927 http://www.medworm.com/index.php?rid=2980926&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1988%3Frss%3D1 A highly sensitive quantitative method for assaying nicotianamine (NA) and 2'-deoxymugineic acid (DMA) using liquid chromatography/electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOF-MS) was developed. The amino and hydroxyl groups of NA and DMA were derivatized using 9-fluorenylmethoxycarbonyl chloride. The amounts of NA and DMA in 10 µl of xylem sap from rice cultivated under iron (Fe)-sufficient and Fe-deficient conditions were quantified without concentration. In Fe-sufficient plants, the concentrations of NA and DMA were almost equal to that of Fe. In Fe-deficient plants, the concentration of NA did not change significantly, whereas that of DMA increased markedly. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980926 Wed, 11 Nov 2009 15:54:39 +0100 2980926 http://www.medworm.com/index.php?rid=2980925&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1982%3Frss%3D1 The poplar GT8E and GT8F glycosyltransferases have previously been shown to be associated with wood formation, but their roles in the biosynthesis of wood components are not known. Here, we show that PoGT8E and PoGT8F are expressed in vessels and fibers during wood formation and their encoded proteins are predominantly located in the endoplasmic reticulum. We demonstrate that expression of PoGT8E and PoGT8F in the Arabidopsis parvus mutant rescues the defects in the content and structure of glucuronoxylan conferred by the parvus mutation. These findings suggest that PoGT8E and PoGT8F are involved in glucuronoxylan biosynthesis during wood formation in poplar. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980925 Wed, 11 Nov 2009 15:54:39 +0100 2980925 http://www.medworm.com/index.php?rid=2980924&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1977%3Frss%3D1 In this study, we identified an antimonite [Sb(III)] transporter from Arabidopsis thaliana. We examined the Sb(III) tolerance of the disruption mutant plants of arsenite [As(III)] transporters, nodulin 26-like intrinsic proteins (NIPs), since Sb(III) is similar to As(III) in structure. One of the mutants, nip1;1, showed Sb(III) tolerance and accumulated less Sb. Furthermore, yeast expressing NIP1;1 accumulated twice as much Sb as control. These data indicate that NIP1;1 transports Sb(III) and determines the Sb(III) sensitivity of A. thaliana. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980924 Wed, 11 Nov 2009 15:54:39 +0100 2980924 http://www.medworm.com/index.php?rid=2980923&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1965%3Frss%3D1 In this study, we analyzed the functions of AtRPA70a, which is most similar to human RPA70 among four paralogs in Arabidopsis thaliana. RNA blot analysis showed that AtRPA70a is expressed ubiquitously in plant organs containing differentiated and meristematic tissues, while its expression was up-regulated in response to DNA damage stress. Yeast two-hybrid and co-immunoprecipitation analyses showed that AtRPA70a interacted preferentially with Arabidopsis RPA32a, one of two paralogs. Inactivation of AtRPA70a by T-DNA insertion did not affect growth under normal conditions, but resulted in increased sensitivity to genotoxic agents such as methylmethane sulfonate, bleomycin and hydroxyurea. Terminal restriction fragment analysis revealed that telomere lengths in an AtRPA70a-deficient line were... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980923 Wed, 11 Nov 2009 15:54:39 +0100 2980923 http://www.medworm.com/index.php?rid=2980922&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1950%3Frss%3D1 It has been proposed that the transcriptional regulation of secondary wall biosynthesis in Arabidopsis is controlled by a transcriptional network mediated by SND1 and its close homologs. Uncovering all the transcription factors and deciphering their interrelationships in the network are essential for our understanding of the molecular mechanisms underlying the transcriptional regulation of biosynthesis of secondary walls, the major constituent of wood and fibers. Here, we present functional evidence that the MYB83 transcription factor is another molecular switch in the SND1-mediated transcriptional network regulating secondary wall biosynthesis. MYB83 is specifically expressed in fibers and vessels where secondary wall thickening occurs. Its expression is directly activated by SND1 and its... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980922 Wed, 11 Nov 2009 15:54:39 +0100 2980922 http://www.medworm.com/index.php?rid=2980921&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1933%3Frss%3D1 For systematic and genome-wide analyses of rice gene functions, we took advantage of the full-length cDNA overexpresser (FOX) gene-hunting system and generated >12 000 independent FOX-rice lines from >25 000 rice calli treated with the rice-FOX Agrobacterium library. We found two FOX-rice lines generating green calli on a callus-inducing medium containing 2,4-D, on which wild-type rice calli became ivory yellow. In both lines, OsGLK1 cDNA encoding a GARP transcription factor was ectopically overexpressed. Using rice expression-microarray and northern blot analyses, we found that a large number of nucleus-encoded genes involved in chloroplast functions were highly expressed and transcripts of plastid-encoded genes, psaA, psbA and rbcL, increased in the OsGLK1-FOX calli. Transmission e... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980921 Wed, 11 Nov 2009 15:54:39 +0100 2980921 http://www.medworm.com/index.php?rid=2980920&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1923%3Frss%3D1 Oligopeptide transporters (OPTs) are found in fungi, bacteria and plants. The nine Arabidopsis thaliana OPT genes are expressed mainly in the vasculature and are thought to transport tetra- and pentapeptides, and peptide-like substrates such as glutathione. Expression of AtOPT6 in Xenopus laevis oocytes demonstrated that AtOPT6 transports many tetra- and pentapeptides. In addition, AtOPT6 transported reduced glutathione (GSH), a tripeptide, but not oxidized glutathione (GSSG). Recent data showed that Candida albicans OPTs can transport peptides up to eight amino acids in length. AtOPT6 transported mammalian signaling peptides up to 10 amino acids in length and, in addition, known plant development- and nematode pathogenesis-associated peptides up to 13 amino acids long. AtOPT6 displayed hi... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980920 Wed, 11 Nov 2009 15:54:39 +0100 2980920 http://www.medworm.com/index.php?rid=2980919&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1911%3Frss%3D1 Plant male reproductive development is highly organized and sensitive to various environmental stressors, including high temperature. We have established an experimental procedure to evaluate high temperature injury in japonica rice plants. High temperature treatment (39°C/30°C) starting at the microspore stage repeatedly reduced spikelet fertility in our system. Morphological observations revealed that pollen viability in plants exposed to high temperatures was lower than that in control plants. Most pollen grains in high temperature-treated plants displayed a normal round shape and stained reddish purple with Alexander’s reagent; however, the pollen grains were very poorly attached and displayed limited germination on the stigma. To investigate gene regulatory mechanisms in... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980919 Wed, 11 Nov 2009 15:54:39 +0100 2980919 http://www.medworm.com/index.php?rid=2980918&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1898%3Frss%3D1 The TL29 protein is one of the more abundant proteins in the thylakoid lumen of plant chloroplasts. Based on its sequence homology to ascorbate peroxidases, but without any supporting biochemical evidence, TL29 was suggested to be involved in the plant defense system against reactive oxygen species and consequently renamed to APX4. Our in vivo and in vitro analyses failed to show any peroxidase activity associated with TL29; it bound neither heme nor ascorbate. Recombinant overexpressed TL29 had no ascorbate-dependent peroxidase activity, and various mutational analyses aiming to convert TL29 into an ascorbate peroxidase failed. Furthermore, in the thylakoid lumen no such activity could be associated with TL29 and, additionally, TL29 knock-out mutants did not show any decreased peroxidase ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980918 Wed, 11 Nov 2009 15:54:39 +0100 2980918 http://www.medworm.com/index.php?rid=2980917&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1886%3Frss%3D1 Several brittle culm (bc) mutants known in grasses are considered excellent materials to study the process of secondary cell wall formation. The brittle phenotype of the rice bc5 (brittle node) mutant appears exclusively in the developed nodes, which is distinct from other bc mutants (bc1, 2, 3, 4, 6 and 7) that show the brittle phenotype in culms and leaves. To address the defects of the rice bc5 mutant in node-specific cell wall formation, we analyzed tissue morphology and cell wall composition. The bc5 mutation was found to affect the cell wall deposition of node sclerenchyma tissues at 1 week after heading, the stage at which the cell wall sugar content is reduced, in the bc5 nodes, compared with wild-type nodes. Moreover, decreased accumulation of lignin and thickness of cell walls in... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980917 Wed, 11 Nov 2009 15:54:39 +0100 2980917 http://www.medworm.com/index.php?rid=2980916&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1874%3Frss%3D1 Since the early days of Darwin, monocot coleoptiles have been used to investigate indole-3-acetic acid (IAA) production, polar transport and tropisms. Here, using maize coleoptiles, we first showed that polar transport of IAA synthesized at the tip region is regulated by ZmPIN(s). Then, the TIR/AFBs-mediated auxin signaling pathway corresponds to the asymmetric IAA flow after gravi-stimulus, which results in tropic curvature. When [13C1115N2]Trp was applied to coleoptile tips, substantial amounts of the stable isotope were incorporated into IAA at the tip region, and the labeled IAA was transported in a polar manner at approximately 7 mm h–1. Immunohistochemical analyses revealed that ZmPIN1(s) was present in almost all cells. ZmPIN1(s) showed a relatively non-polar distribution at t... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980916 Wed, 11 Nov 2009 15:54:39 +0100 2980916 http://www.medworm.com/index.php?rid=2980915&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1865%3Frss%3D1 Transcripts from mitochondrial and chloroplast DNA of land plants often undergo cytidine to uridine conversion-type RNA editing events. RESOPS is a newly built database that specializes in displaying RNA editing sites of land plant organelles on protein three-dimensional (3D) structures to help elucidate the mechanisms of RNA editing for gene expression regulation. RESOPS contains the following information: unedited and edited cDNA sequences with notes for the target nucleotides of RNA editing, conceptual translation from the edited cDNA sequence in pseudo-UniProt format, a list of proteins under the influence of RNA editing, multiple amino acid sequence alignments of edited proteins, the location of amino acid residues coded by codons under the influence of RNA editing in protein 3D struc... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980915 Wed, 11 Nov 2009 15:54:39 +0100 2980915 http://www.medworm.com/index.php?rid=2980914&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F11%2F1857%3Frss%3D1 Sexual reproduction is an important biological event not only for evolution but also for breeding in plants. It is a well known fact that Charles Darwin (1809–1882) was interested in the reproduction system of plants as part of his concept of ‘species’ and ‘evolution.’ His keen observation and speculation is timeless even in the current post-genome era. In the Darwin anniversary year of 2009, I have summarized recent molecular genetic studies of plant reproduction, focusing especially on male gametophyte development, pollination and fertilization. We are just beginning to understand the molecular mechanisms of the elaborate reproduction system in flowering plants, which have been a mystery for >100 years. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2980914 Wed, 11 Nov 2009 15:54:39 +0100 2980914 http://www.medworm.com/index.php?rid=2875790&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1856%3Frss%3D1 (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875790 Thu, 08 Oct 2009 15:39:57 +0100 2875790 http://www.medworm.com/index.php?rid=2875789&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1851%3Frss%3D1 Four out of five members of the RBCS multigene family (OsRBCS2–OsRBCS5) were highly expressed in leaf blades of rice (Oryza sativa L.) irrespective of plant growth stage, whereas accumulation of all RBCS mRNAs in leaf sheaths, roots and developing spikelets was quite low. A highly positive correlation was observed between total RBCS and RBCL mRNA levels and Rubisco content at their maxima, irrespective of tissue and growth stage. The results indicate that the total RBCS mRNA level may be a primary determinant for maximal Rubisco protein content and that Rubisco gene expression is well coordinated through the whole life of rice. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875789 Thu, 08 Oct 2009 15:39:57 +0100 2875789 http://www.medworm.com/index.php?rid=2875788&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1840%3Frss%3D1 Determination of the role of mitochondrial (mt) ATP synthesis in plant metabolism is complicated by chloroplastic ATP synthesis. To differentiate ATP synthesis from these two organelles, we created transgenic Arabidopsis plants in which two different subunits of the mt ATP synthase, the oligomycin sensitivity-conferring protein (OSCP) (=) (ATP5) and the (ATP3) subunit, were expressed individually in antisense orientation under the control of a dexamethasone-inducible promoter. The phenotypic effects of antisense expression were identical for both atp5 and atp3. Seedling lethality resulted from induction during germination in the light, demonstrating the essentiality of both gene products. Reduced expression of either gene resulted in stunting of dark-grown (etiolated) seedlings, downward c... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875788 Thu, 08 Oct 2009 15:39:57 +0100 2875788 http://www.medworm.com/index.php?rid=2875787&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1826%3Frss%3D1 The textbook image of the plant vacuole sitting passively in the centre of the cell is not always correct. We observed vacuole dynamics in the epidermal cells of red onion (Allium cepa) bulbs, using confocal microscopy to detect autofluorescence from the pigment anthocyanin. The central vacuole was penetrated by highly mobile transvacuolar strands of cytoplasm, which were also visible in concurrent transmitted light images. Tubular vacuoles also extended from the large central vacuole and radiated through the cortical cytoplasm. These tubules were thin, having a diameter of about 1.5 µm, and were connected to the central vacuole as shown by fluorescence recovery after photobleaching (FRAP) experiments. The tubules were bounded by the tonoplast, as revealed by transient expression of ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875787 Thu, 08 Oct 2009 15:39:57 +0100 2875787 http://www.medworm.com/index.php?rid=2875786&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1815%3Frss%3D1 For plants, light is an indispensable resource. However, it also causes a loss of photosynthetic activity associated with photoinactivation of photosystem II (PSII). In studies of the mechanism of this photoinactivation, there are two conflicting hypotheses at present. One is that excess energy received by leaves, being neither utilized by photosynthesis nor dissipated safely in non-photochemical quenching, causes the photoinactivation. The other involves a two-step mechanism in which excitation of Mn by photons is the primary cause. In the former hypothesis, photoinactivation of PSII should not occur in low light that provides little excess energy, but in the latter hypothesis it should. Therefore, we tested these two hypotheses in different irradiances. We used a system that can measure ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875786 Thu, 08 Oct 2009 15:39:57 +0100 2875786 http://www.medworm.com/index.php?rid=2875785&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1801%3Frss%3D1 Chloroplast thylakoid lumen of Arabidopsis thaliana contains 16 immunophilins, five cyclophilins and 11 FK506-binding proteins (FKBPs), which are considered protein folding catalysts, although only two of them, AtFKBP13 and AtCYP20-2, possess peptidyl–prolyl cis/trans isomerase (PPIase) activity. To address the question of the physiological significance of this activity, we obtained and characterized Arabidopsis mutants deficient in the most active PPIase, AtFKBP13, and a double mutant deficient in both AtFKBP13 and AtCYP20-2. Two-dimensional gel electrophoresis of isolated thylakoid lumen, as well as immunoblotting analyses of major photosynthetic membrane protein complexes did not reveal differences in protein composition between the mutants and the wild type. No changes in the rel... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875785 Thu, 08 Oct 2009 15:39:56 +0100 2875785 http://www.medworm.com/index.php?rid=2875784&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1786%3Frss%3D1 Seed imbibition is a prerequisite for subsequent dormancy and germination control. Here, we investigated imbibition responses of Arabidopsis seeds by transcriptomic and hormone profile analyses using dormant [Cape Verde Islands (Cvi)] and non-dormant [Columbia (Col)] accessions. Once imbibed, seeds of both accessions swelled most up to 3 h, reflecting water uptake. Microarray analysis showed that in both accessions, seeds imbibed for 15 min, 30 min and 1 h were less active in gene expression than at 3 h. More than 2,000 genes were either up-regulated or down-regulated in seeds imbibed for 3 h. Some genes up-regulated at 3 h were already induced in seeds imbibed for 1 h, suggestive of genome reprogramming early after the onset of imbibition. Imbibition-induced genes in seeds imbibed fo... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875784 Thu, 08 Oct 2009 15:39:56 +0100 2875784 http://www.medworm.com/index.php?rid=2875783&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1774%3Frss%3D1 Phototropin family photoreceptors, phot1 and phot2, in Arabidopsis thaliana control the blue light (BL)-mediated phototropic responses of the hypocotyl, chloroplast relocation movement and stomatal opening. Phototropic responses in dark-grown tissues have been well studied but those in de-etiolated green plants are not well understood. Here, we analyzed phototropic responses of inflorescence stems and petioles of wild-type and phototropin mutant plants of A. thaliana. Similar to the results obtained from dark-grown seedlings, inflorescence stems and petioles in wild-type and phot2 mutant plants showed phototropic bending towards low fluence BL, while in phot1 mutant plants, a high fluence rate of BL was required. phot1 phot2 double mutant plants did not show any phototropic responses even ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875783 Thu, 08 Oct 2009 15:39:56 +0100 2875783 http://www.medworm.com/index.php?rid=2875782&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1761%3Frss%3D1 In higher plants the glutamate dehydrogenase (GDH) enzyme catalyzes the reversible amination of 2-oxoglutarate to form glutamate, using ammonium as a substrate. For a better understanding of the physiological function of GDH either in ammonium assimilation or in the supply of 2-oxoglutarate, we used transgenic tobacco (Nicotiana tabacum L.) plants overexpressing the two genes encoding the enzyme. An in vivo real time 15N-nuclear magnetic resonance (NMR) spectroscopy approach allowed the demonstration that, when the two GDH genes were overexpressed individually or simultaneously, the transgenic plant leaves did not synthesize glutamate in the presence of ammonium when glutamine synthetase (GS) was inhibited. In contrast we confirmed that the primary function of GDH is to deaminate Glu. When... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875782 Thu, 08 Oct 2009 15:39:56 +0100 2875782 http://www.medworm.com/index.php?rid=2875781&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1750%3Frss%3D1 The chloroplast-encoded Ycf4 plays an essential role in PSI complex assembly in the green alga Chlamydomonas reinhardtii. To gain insight into how Ycf4 functions, we generated several mutants in which residues R120, E179 and/or E181, which are conserved among oxygenic photosynthetic organisms, were changed to A or Q. Although the single mutants R120A and R120Q accumulated 80% less Ycf4 than the wild type, they assembled a functional PSI complex and grew photosynthetically like the wild type. Thus we inferred that under laboratory growth conditions, wild-type cells accumulate a superfluous amount of Ycf4. Single mutants E179A, E179Q and E181Q assembled a functional PSI complex like the wild type, whereas the single mutant E181A and double mutant E179/181A accumulated a functional PSI comple... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875781 Thu, 08 Oct 2009 15:39:56 +0100 2875781 http://www.medworm.com/index.php?rid=2875780&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1736%3Frss%3D1 In C4 plants, mesophyll (M) chloroplasts are randomly distributed along the cell walls, while bundle sheath (BS) chloroplasts are typically located in either a centripetal or centrifugal position. We investigated whether these intracellular positions are affected by environmental stresses. When mature leaves of finger millet (Eleusine coracana) were exposed to extremely high intensity light, most M chloroplasts aggregatively re-distributed to the BS side, whereas the intracellular arrangement of BS chloroplasts was unaffected. Compared with the homologous light-avoidance movement of M chloroplasts in C3 plants, it requires extremely high light (3,000–4,000 µmol m–2 s–1) and responds more slowly (distinctive movement observed in 1 h). The high light-induced movement ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875780 Thu, 08 Oct 2009 15:39:56 +0100 2875780 http://www.medworm.com/index.php?rid=2875779&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F10%2F1727%3Frss%3D1 Arabidopsis thaliana increases cellular phosphatidylcholine (PC) content during cold acclimation by up-regulating PC biosynthesis. The A. thaliana genes CCT1 and CCT2 encode CTP:phosphorylcholine cytidylyltransferases (CCTs; EC 2.7.7.15), which regulate PC biosynthesis via the CDP–choline pathway. We isolated the T-DNA-tagged knockout mutants cct1 and cct2 of A. thaliana (Wassilevskaja; WS). CCT activity in cct1 and cct2 plants accounted for 29 and 79% to the cellular CCT activity of WS plants, respectively. When plants were exposed to 2°C for 7 d, CCT activity increased in both cct1 and cct2 plants, and immunoblot analyses revealed that cct1 contained an increased level of CCT2 protein whereas cct2 exhibited little increase in CCT1 level. For each mutant grown at 23°C, CCT a... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2875779 Thu, 08 Oct 2009 15:39:56 +0100 2875779 http://www.medworm.com/index.php?rid=2774514&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1721%3Frss%3D1 The current literature offers contradictory results regarding the role of the proteasome subunit RPN1a in Arabidopsis development. Here we show that plants lacking RPN1a are viable and have increased cell sizes, decreased heat shock tolerance, increased oxidative stress tolerance and other phenotypes characteristic for 26S proteasome subunit mutants. These results strengthen our contention that most of the phenotypes of 26S proteasome mutants in Arabidopsis described to date reflect a general impairment in 26S proteasome function rather than a specific defect of a single subunit, and suggest that the role of the RPN1a subunit during embryogenesis needs to be reconsidered. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774514 Mon, 07 Sep 2009 23:00:00 +0100 2774514 http://www.medworm.com/index.php?rid=2774513&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1715%3Frss%3D1 MicroRNAs (miRNAs) are 20–24 nucleotide endogenous regulatory molecules conserved in higher eukaryotes. In Arabidopsis, miRNAs are produced through step-wise cleavages of primary miRNA precursors (pri-miRNAs) by DICER-LIKE1 (DCL1). This cleavage step is also supported by a double-stranded RNA-binding protein, HYPONASTIC LEAVES1 (HYL1). In many cases, mature miRNA is predominantly incorporated into an endonuclease, ARGONAUTE1 (AGO1), which degrades miRNA-targeted mRNAs. Here, we examined and revealed whole genome transcriptomes in ago1-25 and hyl1-2 mutants using tiling arrays. The data in this paper are valuable for understanding the relationship between the miRNA pathway and its effect on transcriptomes. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774513 Mon, 07 Sep 2009 23:00:00 +0100 2774513 http://www.medworm.com/index.php?rid=2774512&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1710%3Frss%3D1 Rice glutelin RNAs are localized to the cisternal endoplasmic reticulum (ER) by a regulated RNA transport process requiring specific cis-localization elements. We set out to identify these glutelin sequences by their dominant character of being able to re-direct the normal protein body ER localization of a maize 10 kDa -zein RNA to the cisternal ER. In situ RNA localization analysis showed that the glutelin RNA contains multiple cis-localization elements; two located at the 5' and 3' ends of the coding sequences and a third located within the 3'-untranslated region. These three regions contain two conserved sequences, suggesting that these RNA recognition signals may be sequence based. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774512 Mon, 07 Sep 2009 23:00:00 +0100 2774512 http://www.medworm.com/index.php?rid=2774511&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1695%3Frss%3D1 The p70 ribosomal S6 kinase (p70s6k) signaling pathway plays a key role in regulating the cell cycle via translational regulation of specific 5'TOP mRNAs. However, the function of this signaling pathway is still poorly understood in plants. Ectopic expression of the lily putative p70s6k gene, LS6K1, resulted in up-regulation of NAP (NAC-LIKE, ACTIVATED BY AP3/PI) and PISTILLATA (PI) expression, and significantly inhibited cell expansion for petals and stamens, resulting in the male sterility phenotype in transgenic Arabidopsis. Sequence analysis revealed that the genes involved in petal and stamen development, such as APETALA3 (AP3), PI and SUPERMAN (SUP), probably encode 5'TOP mRNAs. Green fluorescent protein (GFP), fused to oligopyrimidine tract sequences that were identified in the 5'-u... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774511 Mon, 07 Sep 2009 23:00:00 +0100 2774511 http://www.medworm.com/index.php?rid=2774510&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1681%3Frss%3D1 Mammalian receptor for activated C kinase 1 (RACK1) is a versatile scaffold protein, playing regulatory roles in multiple signal transduction pathways. Moreover, RACK1 interacts with the heterotrimeric G-proteins (G-proteins) and regulates some specific functions of Gβ. Although the protein sequences of both RACK1 and G-proteins are highly conserved in Arabidopsis, their relationship remains elusive. Here we provide genetic and biochemical evidence that Arabidopsis RACK1 and G-proteins may act through a mechanism that is distinct from their counterparts in mammals. Loss-of-function alleles of RACK1A (the most abundantly expressed RACK1 gene in Arabidopsis) do not appear to share morphological and developmental phenotypes with loss-of-function alleles of GPA1 (encoding the sole G in Ar... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774510 Mon, 07 Sep 2009 23:00:00 +0100 2774510 http://www.medworm.com/index.php?rid=2774509&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1674%3Frss%3D1 It is widely believed that the photosystem II (PSII) complex may function as a dimer in the thylakoid membrane. Here, we report experimental conversion from the monomeric PSII to the dimeric form by treatment with high concentrations of n-dodecyl-β-d-maltopyranoside (DM). The content of the PSII monomer in a PsbTc deletion mutant was much higher than in the wild type when solubilized with low concentrations of DM. However, upon treatment with higher concentrations of DM, the PSII dimer was also recovered in the PsbTc deletion mutant. These results suggest that there are at least two distinct processes of dimerization: (i) PsbTc dependent and (ii) DM induced. We discuss the results with regard to the native assembly form(s) of PSII. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774509 Mon, 07 Sep 2009 23:00:00 +0100 2774509 http://www.medworm.com/index.php?rid=2774508&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1663%3Frss%3D1 Dark-operative protochlorophyllide (Pchlide) oxido-reductase (DPOR) is a nitrogenase-like enzyme that catalyzes Pchlide reduction, the penultimate step of chlorophyll a biosynthesis. DPOR is distributed widely among oxygenic phototrophs such as cyanobacteria, green algae and gymnosperms. To determine how DPOR operates in oxygenic photosynthetic cells, we constructed two shuttle vectors for overexpression of Strep-tagged L-protein (ChlL) and Strep-tagged NB-protein (ChlN–ChlB) in Leptolyngbya boryana (formerly Plectonema boryanum) and introduced them into mutants lacking chlL and chlB. Both transformants restored the ability to produce chlorophyll in the dark. The DPOR activity was reconstituted by L-protein and NB-protein purified from the transformants under anaerobic conditions. L-... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774508 Mon, 07 Sep 2009 23:00:00 +0100 2774508 http://www.medworm.com/index.php?rid=2774507&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1651%3Frss%3D1 Sucrose synthase (SuSy) is a highly regulated cytosolic enzyme that catalyzes the conversion of sucrose and a nucleoside diphosphate into the corresponding nucleoside diphosphate glucose and fructose. To determine the impact of SuSy activity in starch metabolism and yield in potato (Solanum tuberosum L.) tubers we measured sugar levels and enzyme activities in tubers of SuSy-overexpressing potato plants grown in greenhouse and open field conditions. We also transcriptionally characterized tubers of SuSy-overexpressing and -antisensed potato plants. SuSy-overexpressing tubers exhibited a substantial increase in starch, UDPglucose and ADPglucose content when compared with controls. Tuber dry weight, starch content per plant and total yield of SuSy-overexpressing tubers increased significantl... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774507 Mon, 07 Sep 2009 23:00:00 +0100 2774507 http://www.medworm.com/index.php?rid=2774506&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1636%3Frss%3D1 Ethylene receptor is the first component of ethylene signaling that regulates plant growth, development and stress responses. Previously, we have demonstrated that tobacco subfamily 2 ethylene receptor NTHK1 had Ser/Thr kinase activity, and overexpression of NTHK1 caused large rosette, reduced ethylene sensitivity, and increased salt sensitivity in transgenic Arabidopsis plants. Here we found that N-box mutation in the NTHK1 kinase domain abolished the kinase activity and led to disruption of NTHK1 roles in conferring reduced ethylene sensitivity and salt sensitive response in transgenic Arabidopsis plants. However, N-box mutation had partial effects on NTHK1 regulation of rosette growth and expression of salt- and ethylene-responsive genes AtNAC2, AtERF1 and AtCor6.6. Mutation of conserve... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774506 Mon, 07 Sep 2009 23:00:00 +0100 2774506 http://www.medworm.com/index.php?rid=2774505&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1627%3Frss%3D1 The rice lamina joint is ideal material for investigating the activity of brassinosteroids (BRs) and auxin because of its high sensitivity to these compounds. Using a series of rice BR biosynthetic and receptor mutants, we conducted lamina joint tests to elucidate the mechanism of cross-talk between BR and auxin signaling in lamina joint bending. In BR biosynthetic mutants d2 and brd1, which are defective in C-23 hydroxylase and C-6 oxidase, respectively, the lamina joint response to auxin was significantly higher than that of wild-type plants. The other BR-biosynthetic mutants, brd2, osdwarf4 and d11, which are defective in C-22-hydroxylated BRs, showed less or no response to auxin. These results suggest that C-22-hydroxylated BRs are involved in auxin-induced lamina joint bending. The re... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774505 Mon, 07 Sep 2009 23:00:00 +0100 2774505 http://www.medworm.com/index.php?rid=2774504&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1617%3Frss%3D1 The amyloplast, a form of differentiated plastid, proliferates in sink tissues, where it synthesizes and stores starch granules. Little is known about the molecular mechanism for amyloplast division and development. The rice (Oryza sativa) endosperm provides an excellent model system for studying molecular mechanisms involved in amyloplast division and starch synthesis. We compared amyloplast division processes in the endosperm of wild type and a mutant of ARC5, a member of the dynamin superfamily. Plant growth and fertility of arc5 were not significantly different from the wild type. Unlike binary fission of chloroplast in the leaf, small amyloplasts in the endosperm of wild type divide simultaneously at multiple sites, generating a beads-on-a-string structure. In addition, large amylopla... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774504 Mon, 07 Sep 2009 23:00:00 +0100 2774504 http://www.medworm.com/index.php?rid=2774503&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1600%3Frss%3D1 The paper derives a simple way to calculate the linear relationships between all separable groups of rate constants for de-excitation of Chl a excitation energy. This is done by comparison of the inverse values of chlorophyll fluorescence intensities and is based on the matrix model of Kitajima and Butler and on the lake model of energy exchange among PSII centers. Compared with the outputs of earlier, similar calculations, the results presented here add some linear comparisons of the relative sizes of rate constants without the need for F0' measurement. This enables us to regenerate the same alternative formula to calculate qL as presented previously, in a different and simple form. The same former equation to calculate F0' value from Fm, Fm' and F0 values is also regenerated in our calcu... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774503 Mon, 07 Sep 2009 23:00:00 +0100 2774503 http://www.medworm.com/index.php?rid=2774502&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1587%3Frss%3D1 Two auxin amidohydrolases, BrIAR3 and BrILL2, from Chinese cabbage [Brassica rapa L. ssp. pekinensis (Lour.) Hanelt] were produced by heterologous expression in Escherichia coli, purified, and screened for activity towards N-(indol-3-ylacetyl)–l-alanine (IAA-Ala) and the long-chain auxin–amino acid conjugates, N-[3-(indol-3-yl)propionyl]–l-alanine (IPA-Ala) and N-[4-(indol-3-yl)butyryl]–l-alanine (IBA-Ala). IPA-Ala was shown to be the favored substrate of both enzymes, but BrILL2 was approximately 15 times more active than BrIAR3. Both enzymes cleaved IBA-Ala and IAA-Ala to a lesser extent. The enzyme kinetics were measured for BrILL2 and the obtained parameters suggested similar binding affinities for the long-chain auxin–amino acid conjugates (IPA-Ala and IB... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774502 Mon, 07 Sep 2009 23:00:00 +0100 2774502 http://www.medworm.com/index.php?rid=2774501&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F9%2F1579%3Frss%3D1 In this study, we identified the bile acid:sodium symporter family protein 5 (BASS5) gene in Arabidopsis as a candidate transporter gene involved in methionine-derived GSL (Met-GSL) biosynthesis by means of transcriptome co-expression analysis. Knocking out BASS5 resulted in a decrease of Met-GSLs and concomitant increase of methionine. A transient assay using fluorescence fusion proteins indicated a chloroplastic localization of BASS5. These results supported the idea that BASS5 plays a role in translocation across the chloroplast membranes of the biosynthetic intermediates of Met-GSLs. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2774501 Mon, 07 Sep 2009 23:00:00 +0100 2774501 http://www.medworm.com/index.php?rid=2688467&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1573%3Frss%3D1 The biosynthetic pathway of lutein, the most abundant carotenoid in leaves, has been extensively studied, while its degradation pathway during senescence is poorly understood. We found that a novel carotenoid derivative, lutein 3-acetate, accumulates in senescent leaves of rice (Oryza sativa L.). The change in contents of lutein and lutein 3-acetate suggests that lutein is converted to lutein 3-acetate during senescence. Analysis of mutants involved in light-harvesting complex II (LHCII) accumulation and degradation suggests that the converting activity is induced during senescence and that only free lutein, not lutein bound to LHCII, is converted into lutein 3-acetate. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688467 Sun, 09 Aug 2009 23:00:00 +0100 2688467 http://www.medworm.com/index.php?rid=2688466&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1558%3Frss%3D1 The ubiquitin–proteasome pathway mediates protein degradation and is involved in diverse aspects of plant development and differentiation, including pollen tube elongation and self-incompatibility. We characterized three lily (Lilium longiflorum) SKP1-like genes, LSK1–LSK3, that are specifically expressed in late pollen developmental stages and the elongating pollen tube. The encoded peptide sequences reveal that LSK1–LSK3 share high identity with Arabidopsis ASK1 and contain a putative N-terminal CUL1- and a C-terminal F-box-interacting domain. Yeast two-hybrid and in vitro affinity binding assays revealed that the LSKs associate with lily CULLIN1. In addition, the LSK genes can functionally complement the yeast skp1 deletion mutant YDR328C. To investigate their biologic... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688466 Sun, 09 Aug 2009 23:00:00 +0100 2688466 http://www.medworm.com/index.php?rid=2688465&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1544%3Frss%3D1 The FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1) genes play crucial roles in regulating the vegetative to reproductive phase transition. Orthologs of FT/TFL1 (OnFT and OnTFL1) were isolated and characterized from Oncidium Gower Ramsey. OnFT mRNA was detected in axillary buds, leaves, pseudobulb and flowers. In flowers, OnFT was expressed more in young flower buds than in mature flowers and was predominantly expressed in sepals and petals. The expression of OnFT was regulated by photoperiod, with the highest expression from the 8th to 12th hour of the light period and the lowest expression at dawn. In contrast, the expression of OnTFL1 was only detected in axillary bud and pseudobulb, and was not influenced by light. Ectopic expression of OnFT in transgenic Arabidopsis plants showed ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688465 Sun, 09 Aug 2009 23:00:00 +0100 2688465 http://www.medworm.com/index.php?rid=2688464&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1532%3Frss%3D1 Seed storage proteins are specifically and highly synthesized during seed maturation and are deposited into protein bodies (PBs) via the endoplasmic reticulum (ER) lumen. The accumulation process is mediated by ER chaperones such as luminal binding protein (BiP) and protein disulfide isomerase (PDI). To examine the role of ER chaperones and the relationship between ER chaperones and levels of accumulation of seed storage proteins, we generated transgenic rice plants in which the rice BiP and PDI genes were overexpressed in an endosperm-specific manner under the control of the rice seed storage protein glutelin promoter. The seed phenotype of the PDI-overexpressing transformant was almost identical to that of the wild type, whereas overexpression of BiP resulted in transgenic rice seed that... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688464 Sun, 09 Aug 2009 23:00:00 +0100 2688464 http://www.medworm.com/index.php?rid=2688463&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1522%3Frss%3D1 In this study CP was experimentally characterized by HPLC analysis as an acid polysaccharide of mannose, galacturonic acid, xylose and rhamnose. Both calcification (estimated from 45Ca uptake) and CP production (estimated from uronic acid quantification) were stimulated under Pi-deficient conditions but strongly suppressed under Pi-sufficient conditions. When cells were transferred from Pi-sufficient to Pi-deficient conditions the production of neutral polysaccharides (NP)—storage glucans—ceased rapidly after a temporary increase in the presence of Pi, and CP production started to increase after Pi was almost depleted. Under Pi-sufficient conditions NP production increased, concomitant with stimulation of cell growth. Calcification increased gradually, but photosynthetic 14CO2 ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688463 Sun, 09 Aug 2009 23:00:00 +0100 2688463 http://www.medworm.com/index.php?rid=2688462&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1507%3Frss%3D1 The cyanobacterium Fremyella diplosiphon can alternate its light-harvesting pigments, a process called comple-mentary chromatic adaptation (CCA), allowing it to photosynthesize in green light (GL) and in fluctuating light conditions. Nevertheless, F. diplosiphon requires chlorophylls for photosynthesis under all light conditions. Two alternative enzymes catalyze the penultimate step of chlorophyll synthesis, light-dependent protochlorophyllide oxidoreductase (LPOR) and dark-operative protochlo-rophyllide oxidoreductase (DPOR). DPOR enzymatic activity is light independent, while LPOR requires light. Therefore, we hypothesize that F. diplosiphon up-regulates DPOR gene expression in GL, so that DPOR is more abundant when LPOR is less functional. We cloned the genes encoding the three subunits... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688462 Sun, 09 Aug 2009 23:00:00 +0100 2688462 http://www.medworm.com/index.php?rid=2688461&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1493%3Frss%3D1 Interaction and cross-talk between microtubules and actin microfilaments are important for the cell axis and polarity during plant cell growth and development, but little is known about the molecular components of this interaction. Plant kinesins with a calponin-homology domain (KCHs) were recently identified and associated with a putative role in microtubule–microfilament cross-linking. KCHs belong to a distinct branch of the minus end-directed kinesin subfamily and so far have only been identified in land plants including the mosses. Here we report the identification of a new KCH from rice (Oryza sativa), OsKCH1, and show that OsKCH1 is associated with cortical microtubules and actin microfilaments in vivo. Furthermore, OsKCH1 is shown to bind to micro-tubules and actin microfilame... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688461 Sun, 09 Aug 2009 23:00:00 +0100 2688461 http://www.medworm.com/index.php?rid=2688460&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1479%3Frss%3D1 The FCA protein is involved in controlling flowering time and plays more general roles in RNA-mediated chromatin silencing in Arabidopsis. It contains two RNA-binding domains and a WW domain. The FCA protein interacts with FY, a polyadenylation factor, via its WW domain. We previously characterized a rice gene, OsFCA, which was homologous to FCA. Here, we found that the OsFCA protein could interact through its WW domain with the following proteins: OsFY, a protein containing a CID domain present in RNA-processing factors such as Pcf11 and Nrd1; a protein similar to splicing factor SF1; a protein similar to FUSE splicing factor; and OsMADS8. The FY protein is associated with the 3' end processing machinery in Arabidopsis. Thus, we examined interactions between OsFY and the rice homologs (Os... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688460 Sun, 09 Aug 2009 23:00:00 +0100 2688460 http://www.medworm.com/index.php?rid=2688459&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1463%3Frss%3D1 The hydroxysteroid dehydrogenase HSD1, identified in the proteome of oil bodies from mature Arabidopsis seeds, is encoded by At5g50600 and At5g50700, two gene copies anchored on a duplicated region of chromosome 5. Using a real-time quantitative reverse transcriptase–polymerase chain reaction (RT–PCR) approach, the accumulation of HSD1 mRNA was shown to be specifically and highly induced in oil-accumulating tissues of maturing seeds. HSD1 mRNA disappeared during germination. The activity of HSD1 promoter and the localization of HSD1 transcripts by in situ hybridization were consistent with this pattern. A complementary set of molecular and genetic analyses showed that HSD1 is a target of LEAFY COTYLEDON2, a transcriptional regulator able to bind the promoter of HSD1. Immunoblot... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688459 Sun, 09 Aug 2009 23:00:00 +0100 2688459 http://www.medworm.com/index.php?rid=2688458&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1449%3Frss%3D1 Plant mitochondria have multiple energy-dissipating components in the respiratory chain. It is known that these components are induced under several stress conditions. Here we examined whether the gene expression pattern and its regulatory mechanism under high light (HL) conditions are different among the respiratory components in Arabidopsis leaves. Alternative oxidase (AOX) gene expression (AOX1a and AOX1c) and amount of protein were elevated after exposure to HL. In addition to AOX, the expression of other respiratory genes, including NDA1, NDB2, NDC1, UCP1, UCP5, COX6b and CI76, was also induced by HL. NDB2 was co-expressed with AOX1a, but other HL-induced genes showed a distinct expression pattern. Manipulation of photosynthesis or respiration using several chemicals revealed that whi... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688458 Sun, 09 Aug 2009 23:00:00 +0100 2688458 http://www.medworm.com/index.php?rid=2688457&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1439%3Frss%3D1 In the cyanobacterium Synechocystis sp. PCC 6803, the histidine kinase Hik33 regulates the expression of several stress-inducible genes. Recently, a yeast two-hybrid screen revealed a specific interaction between Hik33 and a small protein, Ssl3451. To investigate the function of Ssl3451, we developed an assay to monitor the autophosphorylation of Hik33 in vitro. Addition of Ssl3451 to the reaction mixture dramatically enhanced the autophosphorylation activity of Hik33. Pulse–chase experiments revealed that Ssl3451 stimulated the autophosphorylation of Hik33 but did not affect its dephosphorylation. These findings indicated that Ssl3451 might be an activator of Hik33. When the amount of Hik33 was kept constant and the amount of Ssl3451 was increased in the reaction mixture, the extent... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688457 Sun, 09 Aug 2009 23:00:00 +0100 2688457 http://www.medworm.com/index.php?rid=2688456&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1425%3Frss%3D1 Four AP1/AGL9 functional MADS box genes were characterized from the orchid (Oncidium Gower Ramsey). OMADS6 is a SEP3 ortholog, OMADS11 is a SEP1/2 ortholog, OMADS7 is an AGL6-like gene and OMADS10 is a putative paleoAP1 ortholog. The identity of these four genes was further supported by the presence of conserved motifs in the C-terminal regions of the proteins. OMADS6 showed an expression pattern different from SEP3 orthologs, with expression in the sepal, petal, lip and carpel, and was barely detected in the stamen. The expression pattern for OMADS11 was similar to OMADS6 and different from SEP1/2 orthologs since its expression was undetectable in the stamen. The expression pattern for OMADS7 was nearly identical to OMADS6. The similarities in the expression patterns of the SEP/AGL6-like ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688456 Sun, 09 Aug 2009 23:00:00 +0100 2688456 http://www.medworm.com/index.php?rid=2688455&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1416%3Frss%3D1 Recent studies using highly branched mutants of pea, Arabidopsis and rice have demonstrated that strigolactones, a group of terpenoid lactones, act as a new hormone class, or its biosynthetic precursors, in inhibiting shoot branching. Here, we provide evidence that DWARF14 (D14) inhibits rice tillering and may act as a new compo-nent of the strigolactone-dependent branching inhibition pathway. The d14 mutant exhibits increased shoot branch-ing with reduced plant height like the previously characterized strigolactone-deficient and -insensitive mutants d10 and d3, respectively. The d10-1 d14-1 double mutant is phenotypically indistinguishable from the d10-1 and d14-1 single mutants, consistent with the idea that D10 and D14 function in the same pathway. However, unlike with d10, the d14 bran... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688455 Sun, 09 Aug 2009 23:00:00 +0100 2688455 http://www.medworm.com/index.php?rid=2688454&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F8%2F1401%3Frss%3D1 Sugar–sugar glycosyltransferases play an important role in structural diversity of small molecule glycosides in higher plants. We isolated a cDNA clone encoding a sugar–sugar glucosyltransferase (CaUGT3) catalyzing 1,6-glucosylation of flavonol and flavone glucosides for the first time from Catharanthus roseus. CaUGT3 exhibited a unique glucosyl chain elongation activity forming not only gentiobioside but also gentiotrioside and gentiotetroside in a sequential manner. We investigated the functional properties of CaUGT3 using homology modeling and site-directed mutagenesis, and identified amino acids positioned in the acceptor-binding pocket as crucial for providing enough space to accommodate flavonoid glucosides instead of flavonoid aglycones. These results provide basic infor... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2688454 Sun, 09 Aug 2009 23:00:00 +0100 2688454 http://www.medworm.com/index.php?rid=2594361&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1393%3Frss%3D1 The promoters of the three Arabidopsis nuclear genes encoding mitochondrial cytochrome c oxidase subunit 6b (AtCOX6b) have similar expression patterns, with preferential expression in anthers and meristems, and are induced by sucrose and etiolation. Additionally, induction of AtCOX6b-1 by GA3 and AtCOX6b-3 by 6-benzylaminopurine was observed. Site II elements (TGGGCC/T) present in the three promoters bind common nuclear proteins and are important for basal and induced expression. Induction by sucrose requires, in addition, the integrity of elements with the sequence TACTAA. The results imply the participation of common regulatory factors in the expression of the three Arabidopsis COX6b genes. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594361 Sun, 12 Jul 2009 23:00:00 +0100 2594361 http://www.medworm.com/index.php?rid=2594360&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1387%3Frss%3D1 In this study, we show that the position of the caryopsis in the panicle might affect the level of gene silencing through a difference in temporal and spatial expression patterns between RINO1 and GluB-1 promoters, resulting in a large variation in Pi levels and a small increase in Pi in the transgenic seeds. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594360 Sun, 12 Jul 2009 23:00:00 +0100 2594360 http://www.medworm.com/index.php?rid=2594359&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1382%3Frss%3D1 Like bacteria, plastids contain sigma factors for promoter binding and transcription initiation. Accumulating evidence suggests that members of the plant sigma factor family can have specialized non-redundant roles in terms of promoter preference in various developmental and environmental situations. To specify regulatory determinants, we have chosen pairwise exchange of portions of Arabidopsis sigma coding regions, followed by transformation of the chimeric constructs into a sigma 6 knockout line. The resulting phenotypes and plastid RNA patterns point to an important though not exclusive role for the highly variable N-terminal portion of plant sigma proteins. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594359 Sun, 12 Jul 2009 23:00:00 +0100 2594359 http://www.medworm.com/index.php?rid=2594358&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1364%3Frss%3D1 A global gene expression profiling study at different stages of fiber development was undertaken on two cotton species cultivated for fiber, Gossypium hirsutum (L.) and G. barbadense (L.). A large proportion of the genome was expressed during both fiber elongation and subsequent secondary cell wall thickening. There was a major shift in abundance of transcripts for gene regulation, cell organization and metabolism between fiber elongation and fiber thickening that was fundamentally similar in both species. Each stage had its own distinctive features represented by specific metabolic and regulatory genes, a number of which have been noted previously. Many of the genes expressed in the fibers were of a similar type and developmental expression to those seen in other fiber-producing plants, i... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594358 Sun, 12 Jul 2009 23:00:00 +0100 2594358 http://www.medworm.com/index.php?rid=2594357&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1345%3Frss%3D1 We examined the role of these protein kinases in seed development and germination. These SnRK2 proteins were mainly expressed in the nucleus during seed development and germination. The triple mutant (srk2d srk2e srk2i) was sensitive to desiccation and showed severe growth defects during seed development. It exhibited a loss of dormancy and elevated seed ABA content relative to wild-type plants. The severity of these phenotypes was far stronger than that of any single or double SRK2D, SRK2E and SRK2I mutants, including the srk2d srk2i mutant. The triple mutant had greatly reduced phosphorylation activity in in-gel kinase experiments using basic leucine zipper (bZIP) transcription factors including ABI5. Microarray experiments revealed that 48 and 30% of the down-regulated genes in abi5 and... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594357 Sun, 12 Jul 2009 23:00:00 +0100 2594357 http://www.medworm.com/index.php?rid=2594356&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1329%3Frss%3D1 The pathway of carbon phloem loading was examined in leaf tissues of the forage grass Lolium perenne. The effect of defoliation (leaf blade removal) on sucrose transport capacity was assessed in leaf sheaths as the major carbon source for regrowth. The pathway of carbon transport was assessed via a combination of electron microscopy, plasmolysis experiments and plasma membrane vesicles (PMVs) purified by aqueous two-phase partitioning from the microsomal fraction. Results support an apoplastic phloem loading mechanism. Imposition of an artificial proton-motive force to PMVs from leaf sheaths energized an active, transient and saturable uptake of sucrose (Suc). The affinity of Suc carriers for Suc was 580 µM in leaf sheaths of undefoliated plants. Defoliation induced a decrease of Km ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594356 Sun, 12 Jul 2009 23:00:00 +0100 2594356 http://www.medworm.com/index.php?rid=2594355&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1319%3Frss%3D1 In normal leaf development, a two-dimensional pattern of leaf veins is known to form by differentiation of vascular cells from ground meristem cells in a manner that is regulated by the polar flow of auxin. However, the mechanisms regulating the distribution of auxin in the leaf primordium are largely unknown. Here we show that vacuolar SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors), VAM3 and VTI11, are required for the formation of the leaf vascular network in a dosage-dependent manner. This is the first report to show that the pre-vacuolar compartment (PVC)–vacuole traffic pathway is required for the formation of the leaf vascular network. vam3-4, a VAM3-defective mutant, was found to have an immature vascular network. An analysis of the DR5 reporte... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594355 Sun, 12 Jul 2009 23:00:00 +0100 2594355 http://www.medworm.com/index.php?rid=2594354&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1305%3Frss%3D1 The development of mitochondria during seed germination is essential for plant growth. However, the developmental process is still poorly understood. Temperature plays a key role in soybean germination, and in this study we characterized the mitochondrial ultrastructure and proteome after imbibition at 22, 10 and 4°C for 24 h. The mitochondria from the soybean seed axis can be divided into light and heavy mitochondria by Percoll density gradient centrifugation. The axes imbibed at 4°C mainly contained light mitochondria, which had lower levels of specific mitochondrial enzymes and oxidative phosphorylation activity. In contrast, the axes imbibed at 22°C mainly contained heavy mitochondria, which exhibited higher metabolism. Electron microscopy revealed that mitochondria in... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594354 Sun, 12 Jul 2009 23:00:00 +0100 2594354 http://www.medworm.com/index.php?rid=2594353&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1292%3Frss%3D1 The objective of the present study was to isolate and identify membrane-associated proteins with an ability to interact with boron. Boron-interacting proteins were isolated from root microsomal preparations of arabidopsis (Arabidopsis thaliana) and maize (Zea mays) using phenylboronate affinity chromatography, subsequently separated by two-dimensional gel electrophoresis and identified using MALDI-TOF (matrix-assisted laser desorption ionization-time of flight) peptide mass fingerprinting. Twenty-six boron-binding membrane-associated proteins were identified in A. thaliana, and nine in Z. mays roots. Additional uniden-tified proteins were also present. Common to both species were the β-subunit of mitochondrial ATP synthase, several β-glucosidases, a luminal-binding protein and fr... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594353 Sun, 12 Jul 2009 23:00:00 +0100 2594353 http://www.medworm.com/index.php?rid=2594352&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1277%3Frss%3D1 Arabidopsis PGL1, PGL2, PGL4 and PGL5 are predicted to encode cytosolic isoforms of 6-phosphogluconolactonase (6PGL), whereas PGL3 is predicted to encode a 6PGL that has been shown to localize in both plastids and peroxisomes. Therefore, 6PGL may exist in the cytosol, plastids and peroxisomes. However, the function of 6PGL in these three subcellular locations has not been well defined. Here we show that PGL3 is essential, whereas PGL1, PGL2 and PGL5 are individually dispensable for plant growth and development. Knockdown of PGL3 in the pgl3 mutant leads to a dramatic decrease in plant size, a significant increase in total glucose-6-phosphate dehydro-genase activity and a marked decrease in cellular redox potential. Interestingly, the pgl3 plants exhibit constitutive pathogenesis-related ge... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594352 Sun, 12 Jul 2009 23:00:00 +0100 2594352 http://www.medworm.com/index.php?rid=2594351&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1260%3Frss%3D1 The objective of this review is to consolidate the current knowledge of physiology, molecular breeding and func-tional genomics which may be influential in integrating breeding and genetic engineering approaches for drought resistance in soybean. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594351 Sun, 12 Jul 2009 23:00:00 +0100 2594351 http://www.medworm.com/index.php?rid=2594350&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1249%3Frss%3D1 Molecular breeding of crops is an efficient way to upgrade plant functions useful to mankind. A key step is forward genetics or positional cloning to identify the genes that confer useful functions. In order to accelerate the whole research process, we have developed an integrated database system powered by an intelligent data-retrieval engine termed PosMed-plus (Positional Medline for plant upgrading science), allowing us to prioritize highly promising candidate genes in a given chromosomal interval(s) of Arabidopsis thaliana and rice, Oryza sativa. By inferentially integrating cross-species information resources including genomes, transcriptomes, proteomes, localizomes, phenomes and literature, the system compares a user’s query, such as phenotypic or functional keywords, with the ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594350 Sun, 12 Jul 2009 23:00:00 +0100 2594350 http://www.medworm.com/index.php?rid=2594349&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1232%3Frss%3D1 Transcription factors (TFs) regulate the expression of genes at the transcriptional level. Modification of TF activity dynamically alters the transcriptome, which leads to metabolic and phenotypic changes. Thus, functional analysis of TFs using ‘omics-based’ methodologies is one of the most important areas of the post-genome era. In this mini-review, we present an overview of Arabidopsis TFs and introduce strategies for the functional analysis of plant TFs, which include both traditional and recently developed technologies. These strategies can be assigned to five categories: bioinformatic analysis; analysis of molecular function; expression analysis; phenotype analysis; and network analysis for the description of entire transcriptional regulatory networks. (Source: Plant and C... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594349 Sun, 12 Jul 2009 23:00:00 +0100 2594349 http://www.medworm.com/index.php?rid=2594348&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1215%3Frss%3D1 Analysis of genetic mutations is one of the most effective ways to investigate gene function. We now have methods that allow for mass production of mutant lines and cells in a variety of model species. Recently, large numbers of mutant lines have been generated by both ‘loss-of-function’ and ‘gain-of-function’ techniques. In parallel, phenotypic information covering various mutant resources has been acquired and released in web-based databases. As a result, significant progress in comprehensive pheno-type analysis is being made through the use of these tools. Arabidopsis and rice are two major model plant species in which genome sequencing projects have been completed. Arabidopsis is the most widely used experimental plant, with a large number of mutant resources an... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594348 Sun, 12 Jul 2009 23:00:00 +0100 2594348 http://www.medworm.com/index.php?rid=2594347&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1201%3Frss%3D1 We have developed a highly sensitive and high-throughput method for the simultaneous analysis of 43 molecular species of cytokinins, auxins, ABA and gibberellins. This method consists of an automatic liquid handling system for solid phase extraction and ultra-performance liquid chromatography (UPLC) coupled with a tandem quadrupole mass spectrometer (qMS/MS) equipped with an electrospray interface (ESI; UPLC-ESI-qMS/MS). In order to improve the detection limit of negatively charged compounds, such as gibberellins, we chemically derivatized fractions containing auxin, ABA and gibberellins with bromocholine that has a quaternary ammonium functional group. This modification, that we call ‘MS-probe’, makes these hormone derivatives have a positive ion charge and permits all compoun... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594347 Sun, 12 Jul 2009 23:00:00 +0100 2594347 http://www.medworm.com/index.php?rid=2594346&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1191%3Frss%3D1 OsRac1, a member of the Rac/Rop GTPase family, plays important roles as a molecular switch in rice innate immunity, and the active form of OsRac1 functions in the plasma membrane (PM). To study the precise localization of OsRac1 in the PM and its possible association with other signaling components, we performed proteomic analysis of DRMs (detergent-resistant membranes) isolated from rice suspension-cultured cells transformed with myc-tagged constitutively active (CA) OsRac1. DRMs are regions of the PM that are insoluble after Triton X-100 treatment under cold conditions and are thought to be involved in various signaling processes in animal, yeast and plant cells. We identified 192 proteins in DRMs that included receptor-like kinases (RLKs) such as Xa21, nucleotide-binding leucine-rich re... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594346 Sun, 12 Jul 2009 23:00:00 +0100 2594346 http://www.medworm.com/index.php?rid=2594345&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1181%3Frss%3D1 In this study, we confirmed their predicted functions by targeted GSL analysis of the knockout mutants, and named the respective genes MAM-IL1/AtleuC1 and MAM-D1/AtIMD1. Metabolic profiling of the knockout mutants of methionine chain elongation enzymes, conducted by means of widely targeted metabolomics, implied that these enzymes have roles in controlling metabolism from methionine to primary and methionine-related secondary metabolites. As shown here, an omics-based approach is an efficient strategy for the functional elucidation of genes involved in metabolism. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594345 Sun, 12 Jul 2009 23:00:00 +0100 2594345 http://www.medworm.com/index.php?rid=2594344&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F7%2F1177%3Frss%3D1 (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2594344 Sun, 12 Jul 2009 23:00:00 +0100 2594344 http://www.medworm.com/index.php?rid=2508741&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1171%3Frss%3D1 Thioglucoside glucohydrolase (myrosinase), TGG1, is a strikingly abundant protein in Arabidopsis guard cells. We investigated responses of tgg1-3, tgg2-1 and tgg1-3 tgg2-1 mutants to abscisic acid (ABA) and methyl jasmonate (MeJA) to clarify whether two myrosinases, TGG1 and TGG2, function during stomatal closure. ABA, MeJA and H2O2 induced stomatal closure in wild type, tgg1-3 and tgg2-1, but failed to induce stomatal closure in tgg1-3 tgg2-1. All mutants and wild type showed Ca2+-induced stomatal closure and ABA-induced reactive oxygen species (ROS)production. A model is discussed in which two myrosinases redundantly function downstream of ROS production and upstream of cytosolic Ca2+ elevation in ABA and MeJA signaling in guard cells. (Source: Plant and Cell Physiology) Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508741 Tue, 09 Jun 2009 23:00:00 +0100 2508741 http://www.medworm.com/index.php?rid=2508740&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1156%3Frss%3D1 We examined the physiological changes in this loss-of-function mutant under high-Zn conditions to gain an understanding of the mechanism of adaptation to Zn stress. When grown in excessive Zn and observed using energy-dispersive X-ray analysis, wild-type roots were found to accumulate Zn in vacuolar-like organelles but mutant roots did not. The Zn content of mutant roots, determined by chemical analysis, was one-third that of wild-type roots grown in high-Zn medium. Severe inhibition of root growth was observed in mtp1-1 seedlings in 500 µM ZnSO4. Suppression of cell division and elonga-tion by excessive Zn was reversible and the cells resumed growth in normal medium. In mutant roots, a marked formation of reactive oxygen species (ROS) appeared in the meristematic zone, where the MTP... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508740 Tue, 09 Jun 2009 23:00:00 +0100 2508740 http://www.medworm.com/index.php?rid=2508739&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1142%3Frss%3D1 The induced defense response in plants towards herbivores is mainly regulated by jasmonates and leads to the accumulation of so-called jasmonate-induced proteins. Recently, a jasmonate (JA) inducible lectin called Nicotiana tabacum agglutinin or NICTABA was discovered in tobacco (N. tabacum cv Samsun) leaves. Tobacco plants also accumulate the lectin after insect attack by caterpillars. To study the functional role of NICTABA, the accumulation of the JA precursor 12-oxophytodienoic acid (OPDA), JA as well as different JA metabolites were analyzed in tobacco leaves after herbivory by larvae of the cotton leafworm (Spodoptera littoralis) and correlated with NICTABA accumulation. It was shown that OPDA, JA as well as its methyl ester can trigger NICTABA accumulation. However, hydroxylation of... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508739 Tue, 09 Jun 2009 23:00:00 +0100 2508739 http://www.medworm.com/index.php?rid=2508738&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1127%3Frss%3D1 To elucidate the mechanism(s) underlying dioecious flower development, the present study analyzed a SUPERMAN (SUP) homolog, SlSUP, which was identified in Silene latifolia. The sex of this plant is determined by heteromorphic X and Y sex chromosomes. It was revealed that SlSUP is a single-copy autosomal gene expressed exclusively in female flowers. Introduction of a genomic copy of SlSUP into the Arabidopsis thaliana sup (sup-2) mutant complemented the excess-stamen and infertile phenotypes of sup-2, and the overexpression of SlSUP in transgenic Arabidopsis plants resulted in reduced stamen numbers as well as the suppression of petal elongation. During the development of the female flower in S. latifolia, the expression of SlSUP is first detectable in whorls 2 and 3 when the normal express... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508738 Tue, 09 Jun 2009 23:00:00 +0100 2508738 http://www.medworm.com/index.php?rid=2508737&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1116%3Frss%3D1 Chloroplast division involves the tubulin-related GTPase FtsZ that assembles into a ring structure (Z-ring) at the mid-chloroplast division site, which is where invagination and constriction of the envelope membranes occur. Z-ring assembly is usually confined to the mid-chloroplast site by a well balanced counteraction of the stromal proteins MinD and MinE. The in vivo mechanisms by which FtsZ nucleates at specific sites, polymerises into a protofil-ament and organises a closed ring of filament bundles remain largely unknown. To clarify the dynamic aspects of FtsZ, we developed a living cell system for simultaneous visualisation of various FtsZ configurations, utilising the Arabidopsis thaliana overexpressor and mutant of the MinE (AtMinE1) gene, which were modified to weakly express green... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508737 Tue, 09 Jun 2009 23:00:00 +0100 2508737 http://www.medworm.com/index.php?rid=2508736&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1099%3Frss%3D1 KORRIGAN1 (KOR1) is a membrane-bound cellulase implicated in cellulose biosynthesis. PttCel9A1 from hybrid aspen (Populus tremula L. x tremuloides Michx.) has high sequence similarity to KOR1 and we demonstrate here that it complements kor1-1 mutants, indicating that it is a KOR1 ortholog. We investigated the function of PttCel9A1/KOR1 in Arabidopsis secondary growth using transgenic lines expressing 35S::PttCel9A1 and the KOR1 mutant line irx2-2. The presence of elevated levels of PttCel9A1/KOR1 in secondary walls of 35S::PttCel9A1 lines was confirmed by in muro visualization of cellulase activity. Compared with the wild type, 35S::PttCel9A1 lines had higher trifluoroacetic acid (TFA)-hydrolyzable glucan contents, similar Updegraff cellulose contents and lower cellulose crystallinity indi... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508736 Tue, 09 Jun 2009 23:00:00 +0100 2508736 http://www.medworm.com/index.php?rid=2508735&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1090%3Frss%3D1 In this study, to elucidate the molecular mechanism of CD, CHS mRNA and siRNA levels in the seed coat were compared between CD-sensitive and CD-tolerant cultivars (Toyomusume and Toyoharuka, respectively). In Toyomusume, the CHS siRNA level was reduced markedly by low temperature treatment, and subsequently the CHS mRNA level increased rapidly after treatment. In contrast, low temperature treatment did not result in severe reduction of the CHS siRNA level in Toyoharuka, and the CHS mRNA level did not increase after the treatment. These results suggest that the rapid increase in CHS mRNA level after low temperature treatment may lead to enhanced pigmentation in some of the seed coat cells and finally in seed coat discoloration. Interestingly, we found a Toyoharuka-specific difference in the... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508735 Tue, 09 Jun 2009 23:00:00 +0100 2508735 http://www.medworm.com/index.php?rid=2508734&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1075%3Frss%3D1 In this report, we demonstrate that PoGT47C, a poplar glycosyltransferase belonging to family GT47, is essential for the normal biosynthesis of GX and the normal secondary wall thickening in the wood of the hybrid poplar Populus alba x tremula. RNA interference (RNAi) inhibition of PoGT47C resulted in a drastic reduction in the thickness of secondary walls, a deformation of vessels and a decreased amount of GX in poplar wood. Structural analysis of GX using nuclear magnetic resonance (NMR) spectroscopy demonstrated that the reducing end of GX from poplar wood contains the tetrasaccharide sequence, β-d-Xylp-(1->3)--l-Rhap-(1->2)--d-GalpA-(1->4)-d-Xylp, and that its abundance was significantly decreased in the GX from the wood of the GT47C-RNAi lines. The transgenic wood was fo... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508734 Tue, 09 Jun 2009 23:00:00 +0100 2508734 http://www.medworm.com/index.php?rid=2508733&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1062%3Frss%3D1 In monocots, starch branching enzyme II (BEII) was functionally differentiated into BEIIa and BEIIb after separation from the dicots, and in cereals BEIIb plays a distinct role in amylopectin biosynthesis in the endosperm. The present study was conducted to examine to what extent a green algal BEII has an overlapping function with BEIIb in starch biosynthesis by introducing the Chlorella BEII gene into an amylose-extender (ae) mutant of rice. Chlorella BEII was found to complement the contribution of the rice endosperm BEIIb to the structures of amylopectin and starch granules because these mutated phenotypes were recovered almost completely to those of the wild type by the expression of Chlorella BEII. When the recombinant BE enzymes were incubated with the rice ae amylopectin, the branch... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508733 Tue, 09 Jun 2009 23:00:00 +0100 2508733 http://www.medworm.com/index.php?rid=2508732&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1049%3Frss%3D1 Recent studies have revealed various functions for the small ubiquitin-related modifier (SUMO) in diverse biological phenomena, such as regulation of cell division, DNA repair and transcription, in yeast and animals. In contrast, only a limited number of proteins have been characterized in plants, although plant SUMO proteins are involved in many physiological processes, such as stress responses, regulation of flowering time and defense reactions to pathogen attack. Here, we reconstituted the Arabidopsis thaliana SUMOylation cascade in Escherichia coli. This system is rapid and effective for the evaluation of the SUMOylation of potential SUMO target proteins. We tested the ability of this system to conjugate the Arabidopsis SUMO isoforms, AtSUMO1, 2, 3 and 5, to a model substrate, AtMYB30,... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508732 Tue, 09 Jun 2009 23:00:00 +0100 2508732 http://www.medworm.com/index.php?rid=2508731&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1041%3Frss%3D1 Actin plays fundamental roles in a wide array of plant functions, including cell division, cytoplasmic streaming, cell morphogenesis and organelle motility. Imaging the actin cytoskeleton in living cells is a powerful methodology for studying these important phenomena. Several useful probes for live imaging of filamentous actin (F-actin) have been developed, but new versatile probes are still needed. Here, we report the application of a new probe called Lifeact for visualizing F-actin in plant cells. Lifeact is a short peptide comprising 17 amino acids that was derived from yeast Abp140p. We used a Lifeact–Venus fusion protein for staining F-actin in Arabidopsis thaliana and were able to observe dynamic rearrangements of the actin meshwork in root hair cells. We also used Lifeact&nda... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508731 Tue, 09 Jun 2009 23:00:00 +0100 2508731 http://www.medworm.com/index.php?rid=2508730&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1032%3Frss%3D1 Mitochondria, the power house of the cell, are one of the most dynamic cell organelles. Although there are several reports on actin- or microtubule-dependent movement of mitochondria in plant cells, intracellular positioning and motility of mitochondria under different light conditions remain open questions. Mitochondria were visualized in living Arabidopsis thaliana leaf cells using green fluorescent protein fused to a mitochondrion-targeting signal. In darkness, mitochondria were distributed randomly in palisade cells. In contrast, mitochondria accumulated along the periclinal walls, similar to the accumulation response of chloroplasts, when treated with weak blue light (470 nm, 4 µmol m–2 s–1). Under strong blue light (100 µmol m–2 s–1), mitochondria ... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508730 Tue, 09 Jun 2009 23:00:00 +0100 2508730 http://www.medworm.com/index.php?rid=2508729&cid=s_32024_171_f&fid=32024&url=http%3A%2F%2Fpcp.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F50%2F6%2F1019%3Frss%3D1 Regulation of the number of cells is critical for development of multicellular organisms. During plant epidermal development, a protodermal cell first makes a fate decision of whether or not to be the meristemoid mother cell (MMC), which undergoes asymmetric cell division forming a meristemoid and its sister cell. The MMC-derived lineage produces all stomatal guard cells and a large proportion of non-guard cells. We demonstrate that a small secretory peptide, EPIDERMAL PATTERING FACTOR 2 (EPF2), is produced by the MMC and its early descendants, and negatively regulates the density of guard and non-guard epidermal cells. Our results suggest that EPF2 inhibits cells from adopting the MMC fate in a non-cell-autonomous manner, thus limiting the number of MMCs. This feedback loop is critical fo... Plant and Cell Physiology journals http://www.medworm.com/rss/comments.php?id=2508729 Tue, 09 Jun 2009 23:00:00 +0100 2508729