| enhanced photosynthetic performance and growth as a consequence of decreasing mitochondrial malate dehydrogenase activity in transgenic tomato plants. | transgenic tomato (solanum lycopersicum) plants expressing a fragment of the mitochondrial malate dehydrogenase gene in the antisense orientation and exhibiting reduced activity of this isoform of malate dehydrogenase show enhanced photosynthetic activity and aerial growth under atmospheric conditions (360 ppm co2). in comparison to wild-type plants, carbon dioxide assimilation rates and total plant dry matter were up to 11% and 19% enhanced in the transgenics, when assessed on a whole-plant bas ... | 2005 | 15665243 |
| characterization of the arabidopsis clb6 mutant illustrates the importance of posttranscriptional regulation of the methyl-d-erythritol 4-phosphate pathway. | the biosynthesis of isopentenyl diphosphate and dimethylallyl diphosphate, the two building blocks for isoprenoid biosynthesis, occurs by two independent pathways in plants. the mevalonic pathway operates in the cytoplasm, and the methyl-d-erythritol 4-phosphate (mep) pathway operates in plastids. plastidic isoprenoids play essential roles in plant growth and development. plants must regulate the biosynthesis of isoprenoids to fulfill metabolic requirements in specific tissues and developmental ... | 2005 | 15659625 |
| vanguard1 encodes a pectin methylesterase that enhances pollen tube growth in the arabidopsis style and transmitting tract. | in flowering plants, penetration of the pollen tube through stigma, style, and transmitting tract is essential for delivery of sperm nuclei to the egg cells embedded deeply within female tissues. despite its importance in plant reproduction, little is known about the underlying molecular mechanisms that regulate the navigation of the pollen tube through the stigma, style, and transmitting tract. here, we report the identification and characterization of an arabidopsis thaliana gene, vanguard1 (v ... | 2005 | 15659637 |
| amyloplasts and vacuolar membrane dynamics in the living graviperceptive cell of the arabidopsis inflorescence stem. | we developed an adequate method for the in vivo analysis of organelle dynamics in the gravity-perceptive cell (endodermis) of the arabidopsis thaliana inflorescence stem, revealing behavior of amyloplasts and vacuolar membranes in those cells. amyloplasts in the endodermis showed saltatory movements even before gravistimulation by reorientation, and these movements were confirmed as microfilament dependent. from our quantitative analysis in the wild type, the gravity-oriented movement of amylopl ... | 2005 | 15689424 |
| the arabidopsis wavy growth 2 protein modulates root bending in response to environmental stimuli. | to understand how the direction of root growth changes in response to obstacles, light, and gravity, we characterized an arabidopsis thaliana mutant, wavy growth 2 (wav2), whose roots show a short-pitch pattern of wavy growth on inclined agar medium. the roots of the wav2 mutant bent with larger curvature than those of the wild-type seedlings in wavy growth and in gravitropic and phototropic responses. the cell file rotations of the root epidermis of wav2-1 in the wavy growth pattern were enhanc ... | 2005 | 15659627 |
| dissection of arabidopsis adp-ribosylation factor 1 function in epidermal cell polarity. | vesicle trafficking is essential for the generation of asymmetries, which are central to multicellular development. core components of the vesicle transport machinery, such as adp-ribosylation factor (arf) gtpases, have been studied primarily at the single-cell level. here, we analyze developmental functions of the arf1 subclass of the arabidopsis thaliana multigene arf family. six virtually identical arf1 genes are ubiquitously expressed, and single loss-of-function mutants in these genes revea ... | 2005 | 15659621 |
| the dof transcription factor obp3 modulates phytochrome and cryptochrome signaling in arabidopsis. | plants perceive subtle changes in light quality and quantity through a set of photoreceptors, including phytochromes and cryptochromes. upon perception, these photoreceptors initiate signal transduction pathways leading to photomorphogenic changes in development. using activation-tagging mutagenesis to identify novel light-signaling components, we have isolated a gain-of-function mutant, sob1-d (suppressor of phytochrome b-4 [phyb-4] dominant), which suppresses the long-hypocotyl phenotype of th ... | 2005 | 15659636 |
| functional genomic analysis of the auxin response factor gene family members in arabidopsis thaliana: unique and overlapping functions of arf7 and arf19. | the auxin response factor (arf) gene family products, together with the auxin/indole-3-acetic acid proteins, regulate auxin-mediated transcriptional activation/repression. the biological function(s) of most arfs is poorly understood. here, we report the identification and characterization of t-dna insertion lines for 18 of the 23 arf gene family members in arabidopsis thaliana. most of the lines fail to show an obvious growth phenotype except of the previously identified arf2/hss, arf3/ett, arf5 ... | 2005 | 15659631 |
| the arabidopsis homology-dependent gene silencing1 gene codes for an s-adenosyl-l-homocysteine hydrolase required for dna methylation-dependent gene silencing. | genes introduced into higher plant genomes can become silent (gene silencing) and/or cause silencing of homologous genes at unlinked sites (homology-dependent gene silencing or hdg silencing). mutations of the homology-dependent gene silencing1 (hog1) locus relieve transcriptional gene silencing and methylation-dependent hdg silencing and result in genome-wide demethylation. the hog1 mutant plants also grow slowly and have low fertility and reduced seed germination. three independent mutants of ... | 2005 | 15659630 |
| the arabidopsis peroxisomal targeting signal type 2 receptor pex7 is necessary for peroxisome function and dependent on pex5. | plant peroxisomal proteins catalyze key metabolic reactions. several peroxisome biogenesis peroxin (pex) genes encode proteins acting in the import of targeted proteins necessary for these processes into the peroxisomal matrix. most peroxisomal matrix proteins bear characterized peroxisomal targeting signals (pts1 or pts2), which are bound by the receptors pex5 or pex7, respectively, for import into peroxisomes. here we describe the isolation and characterization of an arabidopsis peroxin mutant ... | 2005 | 15548601 |
| expression of cellulose synthase-like (csl) genes in insect cells reveals that csla family members encode mannan synthases. | glucuronoarabinoxylan, xyloglucan, and galactomannan are noncellulosic polysaccharides found in plant cell walls. all consist of beta-linked glycan backbones substituted with sugar side chains. although considerable progress has been made in characterizing the structure of these polysaccharides, little is known about the biosynthetic enzymes that produce them. cellulose synthase-like (csl) genes are hypothesized to encode golgi-localized beta-glycan synthases that polymerize the backbones of non ... | 2005 | 15647349 |
| the arabidopsis atr1 myb transcription factor controls indolic glucosinolate homeostasis. | plants derive a number of important secondary metabolites from the amino acid tryptophan (trp), including the growth regulator indole-3-acetic acid (iaa) and defense compounds against pathogens and herbivores. in previous work, we found that a dominant overexpression allele of the arabidopsis (arabidopsis thaliana) myb transcription factor atr1, atr1d, activates expression of a trp synthesis gene as well as the trp-metabolizing genes cyp79b2, cyp79b3, and cyp83b1, which encode enzymes implicated ... | 2005 | 15579661 |
| generation of active pools of abscisic acid revealed by in vivo imaging of water-stressed arabidopsis. | a noninvasive, cell-autonomous reporter system was developed to monitor the generation and distribution of physiologically active pools of abscisic acid (aba). aba response (abi1-1) and biosynthesis (aba2-1) mutants of arabidopsis (arabidopsis thaliana) were used to validate the system in the presence and absence of water stress. in the absence of water stress, low levels of aba-dependent reporter activation were observed in the columella cells and quiescent center of the root as well as in the ... | 2005 | 15618419 |
| the role of the cell cycle machinery in resumption of postembryonic development. | cell cycle activity is required for plant growth and development, but its involvement in the early events that initiate seedling development remains to be clarified. we performed experiments aimed at understanding when cell cycle progression is activated during seed germination, and what its contribution is for proper seedling establishment. to this end, the spatial and temporal expression profiles of a large set of cell cycle control genes in germinating seeds of arabidopsis (arabidopsis thalia ... | 2005 | 15579664 |
| a role of arabidopsis inositol polyphosphate kinase, atipk2alpha, in pollen germination and root growth. | inositol polyphosphates, such as inositol trisphosphate, are pivotal intracellular signaling molecules in eukaryotic cells. in higher plants the mechanism for the regulation of the type and the level of these signaling molecules is poorly understood. in this study we investigate the physiological function of an arabidopsis (arabidopsis thaliana) gene encoding inositol polyphosphate kinase (atipk2alpha), which phosphorylates inositol 1,4,5-trisphosphate successively at the d-6 and d-3 positions, ... | 2005 | 15618435 |
| subcellular localization of arabidopsis 3-hydroxy-3-methylglutaryl-coenzyme a reductase. | plants produce diverse isoprenoids, which are synthesized in plastids, mitochondria, endoplasmic reticulum (er), and the nonorganellar cytoplasm. 3-hydroxy-3-methylglutaryl-coenzyme a reductase (hmgr) catalyzes the synthesis of mevalonate, a rate-limiting step in the cytoplasmic pathway. several branches of the pathway lead to the synthesis of structurally and functionally varied, yet essential, isoprenoids. several hmgr isoforms have been identified in all plants examined. studies based on gene ... | 2005 | 15618432 |
| complementation of sugary-1 phenotype in rice endosperm with the wheat isoamylase1 gene supports a direct role for isoamylase1 in amylopectin biosynthesis. | to examine the role of isoamylase1 (isa1) in amylopectin biosynthesis in plants, a genomic dna fragment from aegilops tauschii was introduced into the isa1-deficient rice (oryza sativa) sugary-1 mutant line em914, in which endosperm starch is completely replaced by phytoglycogen. a. tauschii is the d genome donor of wheat (triticum aestivum), and the introduced fragment effectively included the gene for isa1 for wheat (taisa1) that was encoded on the d genome. in taisa1-expressing rice endosperm ... | 2005 | 15618430 |
| a dead box rna helicase is essential for mrna export and important for development and stress responses in arabidopsis. | an arabidopsis thaliana mutant, cryophyte, was isolated and found to have an enhanced cold stress-induction of the master regulator of cold tolerance, c-repeat binding factor 2 (cbf2), and its downstream target genes. the mutant is more tolerant to chilling and freezing stresses but is more sensitive to heat stress. under warm but not cold growth temperatures, the mutant has a reduced stature and flowers earlier. under long day conditions, flowering of the mutant is insensitive to vernalization. ... | 2005 | 15598798 |
| reverse genetic characterization of cytosolic acetyl-coa generation by atp-citrate lyase in arabidopsis. | acetyl-coa provides organisms with the chemical flexibility to biosynthesize a plethora of natural products that constitute much of the structural and functional diversity in nature. recent studies have characterized a novel atp-citrate lyase (acl) in the cytosol of arabidopsis thaliana. in this study, we report the use of antisense rna technology to generate a series of arabidopsis lines with a range of acl activity. plants with even moderately reduced acl activity have a complex, bonsai phenot ... | 2005 | 15608338 |
| arabidopsis membrane steroid binding protein 1 is involved in inhibition of cell elongation. | a putative membrane steroid binding protein (designated msbp1) was identified and functionally characterized as a negative regulator of cell elongation in arabidopsis thaliana. the msbp1 gene encodes a 220-amino acid protein that can bind to progesterone, 5-dihydrotestosterone, 24-epi-brassinolide (24-ebl), and stigmasterol with different affinities in vitro. transgenic plants overexpressing msbp1 showed short hypocotyl phenotype and increased steroid binding capacity in membrane fractions, wher ... | 2005 | 15608331 |
| the rice coleoptile phototropism1 gene encoding an ortholog of arabidopsis nph3 is required for phototropism of coleoptiles and lateral translocation of auxin. | we isolated a mutant, named coleoptile phototropism1 (cpt1), from gamma-ray-mutagenized japonica-type rice (oryza sativa). this mutant showed no coleoptile phototropism and severely reduced root phototropism after continuous stimulation. a map-based cloning strategy and transgenic complementation test were applied to demonstrate that a nph3-like gene deleted in the mutant corresponds to cpt1. phylogenetic analysis of putative cpt1 homologs of rice and related proteins indicated that cpt1 has an ... | 2005 | 15598797 |
| cross talk between gibberellin and cytokinin: the arabidopsis ga response inhibitor spindly plays a positive role in cytokinin signaling. | spindly (spy) is a negative regulator of gibberellin (ga) responses; however, spy mutants exhibit various phenotypic alterations not found in ga-treated plants. assaying for additional roles for spy revealed that spy mutants are resistant to exogenously applied cytokinin. ga also repressed the effects of cytokinin, suggesting that there is cross talk between the two hormone-response pathways, which may involve spy function. two spy alleles showing severe (spy-4) and mild (spy-3) ga-associated ph ... | 2005 | 15608330 |
| activation of crabs claw in the nectaries and carpels of arabidopsis. | crabs claw (crc), a member of the yabby gene family, is required for nectary and carpel development. to further understand crc regulation in arabidopsis thaliana, we performed phylogenetic footprinting analyses of 5' upstream regions of crc orthologs from three brassicaceae species, including arabidopsis. phylogenetic footprinting efficiently identified functionally important regulatory regions (modules), indicating that crc expression is regulated by a combination of positive and negative regul ... | 2005 | 15598802 |
| the flp proteins act as regulators of chlorophyll synthesis in response to light and plastid signals in chlamydomonas. | in photosynthetic organisms the accumulation of harmful photodynamic chlorophyll precursors is prevented because of the tight regulation of the tetrapyrrole pathway. flu is one of the regulatory factors involved in this process in land plants. we have examined the function of a flu-like gene (flp) from chlamydomonas that gives rise to two flp transcripts through alternative splicing. these transcripts are translated into a short and a long protein that differ by only 12 amino acids but that inte ... | 2005 | 15630026 |
| identification of microspore-active promoters that allow targeted manipulation of gene expression at early stages of microgametogenesis in arabidopsis. | the effective functional analysis of male gametophyte development requires new tools enabling the spatially and temporally controlled expression of both marker genes and modified genes of interest. in particular, promoters driving expression at earlier developmental stages including microspores are required. | 2006 | 17184530 |
| the biological sense of cancer: a hypothesis. | most theories about cancer proposed during the last century share a common denominator: cancer is believed to be a biological nonsense for the organism in which it originates, since cancer cells are believed to be ones evading the rules that control normal cell proliferation and differentiation. in this essay, we have challenged this interpretation on the basis that, throughout the animal kingdom, cancer seems to arise only in injured organs and tissues that display lost or diminished regenerati ... | 2006 | 17173673 |
| a proteomics dissection of arabidopsis thaliana vacuoles isolated from cell culture. | to better understand the mechanisms governing cellular traffic, storage of various metabolites, and their ultimate degradation, arabidopsis thaliana vacuole proteomes were established. to this aim, a procedure was developed to prepare highly purified vacuoles from protoplasts isolated from arabidopsis cell cultures using ficoll density gradients. based on the specific activity of the vacuolar marker alpha-mannosidase, the enrichment factor of the vacuoles was estimated at approximately 42-fold w ... | 2006 | 17151019 |
| a proteomics dissection of arabidopsis thaliana vacuoles isolated from cell culture. | to better understand the mechanisms governing cellular traffic, storage of various metabolites, and their ultimate degradation, arabidopsis thaliana vacuole proteomes were established. to this aim, a procedure was developed to prepare highly purified vacuoles from protoplasts isolated from arabidopsis cell cultures using ficoll density gradients. based on the specific activity of the vacuolar marker alpha-mannosidase, the enrichment factor of the vacuoles was estimated at approximately 42-fold w ... | 2006 | 17151019 |
| the arabidopsis nrt1.1 transporter participates in the signaling pathway triggering root colonization of nitrate-rich patches. | localized proliferation of lateral roots in no(3)(-)-rich patches is a striking example of the nutrient-induced plasticity of root development. in arabidopsis, no(3)(-) stimulation of lateral root elongation is apparently under the control of a no(3)(-)-signaling pathway involving the anr1 transcription factor. anr1 is thought to transduce the no(3)(-) signal internally, but the upstream no(3)(-) sensing system is unknown. here, we show that mutants of the nrt1.1 nitrate transporter display a st ... | 2006 | 17148611 |
| defects in ctp:phosphorylethanolamine cytidylyltransferase affect embryonic and postembryonic development in arabidopsis. | a tilling strategy (for targeting-induced local-scale lesions in genomes) was used in arabidopsis thaliana to isolate mutants of a gene encoding ctp:phosphorylethanolamine cytidylyltransferase (pect; ec 2.7.7.14), a rate-limiting enzyme in phosphatidylethanolamine biosynthesis. a null mutation, pect1-6, caused embryo abortion before the octant stage. however, reciprocal crosses revealed that pect1-6 caused no significant gametophytic defect. in pect1-4, pect activity was decreased by 74%. growth ... | 2006 | 17189343 |
| dynamics of a mobile rna of potato involved in a long-distance signaling pathway. | bel1-like transcription factors interact with knotted1 types to regulate numerous developmental processes. in potato (solanum tuberosum), the bel1 transcription factor st bel5 and its protein partner poth1 regulate tuber formation by mediating hormone levels in the stolon tip. the accumulation of st bel5 rna increases in response to short-day photoperiods, inductive for tuber formation. rna detection methods and heterografting experiments demonstrate that bel5 transcripts are present in phloem c ... | 2006 | 17189340 |
| reduction of benzenoid synthesis in petunia flowers reveals multiple pathways to benzoic acid and enhancement in auxin transport. | in plants, benzoic acid (ba) is believed to be synthesized from phe through shortening of the propyl side chain by two carbons. it is hypothesized that this chain shortening occurs via either a beta-oxidative or non-beta-oxidative pathway. previous in vivo isotope labeling and metabolic flux analysis of the benzenoid network in petunia (petunia hybrida) flowers revealed that both pathways yield benzenoid compounds and that benzylbenzoate is an intermediate between l-phe and ba. to test this hypo ... | 2006 | 17194766 |
| molecular identification and physiological characterization of a novel monosaccharide transporter from arabidopsis involved in vacuolar sugar transport. | the tonoplast monosaccharide transporter (tmt) family comprises three isoforms in arabidopsis thaliana, and tmt-green fluorescent protein fusion proteins are targeted to the vacuolar membrane. tmt promoter-beta-glucuronidase plants revealed that the tonoplast monosaccharide transporter1 (tmt1) and tmt2 genes exhibit a tissue- and cell type-specific expression pattern, whereas tmt3 is only weakly expressed. tmt1 and tmt2 expression is induced by drought, salt, and cold treatments and by sugar. du ... | 2006 | 17158605 |
| the female gametophyte and the endosperm control cell proliferation and differentiation of the seed coat in arabidopsis. | double fertilization of the female gametophyte produces the endosperm and the embryo enclosed in the maternal seed coat. proper seed communication necessitates exchanges of signals between the zygotic and maternal components of the seed. however, the nature of these interactions remains largely unknown. we show that double fertilization of the arabidopsis thaliana female gametophyte rapidly triggers sustained cell proliferation in the seed coat. cell proliferation and differentiation of the seed ... | 2006 | 17172356 |
| developmentally controlled farnesylation modulates atnap1;1 function in cell proliferation and cell expansion during arabidopsis leaf development. | in multicellular organisms, organogenesis requires tight control and coordination of cell proliferation, cell expansion, and cell differentiation. we have identified arabidopsis (arabidopsis thaliana) nucleosome assembly protein 1 (atnap1;1) as a component of a regulatory mechanism that connects cell proliferation to cell growth and expansion during arabidopsis leaf development. molecular, biochemical, and kinetic studies of atnap1;1 gain- or loss-of-function mutants indicate that atnap1;1 promo ... | 2006 | 17041028 |
| arabidopsis reversibly glycosylated polypeptides 1 and 2 are essential for pollen development. | reversibly glycosylated polypeptides (rgps) have been implicated in polysaccharide biosynthesis. to date, to our knowledge, no direct evidence exists for the involvement of rgps in a particular biochemical process. the arabidopsis (arabidopsis thaliana) genome contains five rgp genes out of which rgp1 and rgp2 share the highest sequence identity. we characterized the native expression pattern of arabidopsis rgp1 and rgp2 and used reverse genetics to investigate their respective functions. althou ... | 2006 | 17071651 |
| common plantain. a collection of expressed sequence tags from vascular tissue and a simple and efficient transformation method. | the vascular tissue of higher plants consists of specialized cells that differ from all other cells with respect to their shape and size, their organellar composition, their extracellular matrix, the type of their plasmodesmata, and their physiological functions. intact and pure vascular tissue can be isolated easily and rapidly from leaf blades of common plantain (plantago major), a plant that has been used repeatedly for molecular studies of phloem transport. here, we present a transcriptome a ... | 2006 | 17041024 |
| frigida like 2 is a functional allele in landsberg erecta and compensates for a nonsense allele of frigida like 1. | the landsberg erecta (ler) accession of arabidopsis (arabidopsis thaliana) has a weak allele of the floral inhibitor flowering locus c (flc). flc-ler is weakly up-regulated by the active san feliu-2 (sf2) allele of frigida (fri-sf2), resulting in a moderately late-flowering phenotype. by contrast, the columbia (col) allele of flc is strongly up-regulated by fri-sf2, resulting in a very late-flowering phenotype. in col, the fri-related gene fri like 1 (frl1) is required for fri-mediated up-regula ... | 2006 | 17056759 |
| interactions between mur10/cesa7-dependent secondary cellulose biosynthesis and primary cell wall structure. | primary cell walls are deposited and remodeled during cell division and expansion. secondary cell walls are deposited in specialized cells after the expansion phase. it is presently unknown whether and how these processes are interrelated. the arabidopsis (arabidopsis thaliana) mur10 gene is required for normal primary cell wall carbohydrate composition in mature leaves as well as for normal plant growth, hypocotyl strength, and fertility. the overall sugar composition of young mur10 seedlings i ... | 2006 | 17041031 |
| extracellular gamma-aminobutyrate mediates communication between plants and other organisms. | | 2006 | 17151138 |
| knock-out of the magnesium protoporphyrin ix methyltransferase gene in arabidopsis. effects on chloroplast development and on chloroplast-to-nucleus signaling. | protoporphyrin ix is the last common intermediate between the heme and chlorophyll biosynthesis pathways. the addition of magnesium directs this molecule toward chlorophyll biosynthesis. the first step downstream from the branchpoint is catalyzed by the magnesium chelatase and is a highly regulated process. the corresponding product, magnesium protoporphyrin ix, has been proposed to play an important role as a signaling molecule implicated in plastid-to-nucleus communication. to get more informa ... | 2006 | 17135235 |
| knock-out of the magnesium protoporphyrin ix methyltransferase gene in arabidopsis. effects on chloroplast development and on chloroplast-to-nucleus signaling. | protoporphyrin ix is the last common intermediate between the heme and chlorophyll biosynthesis pathways. the addition of magnesium directs this molecule toward chlorophyll biosynthesis. the first step downstream from the branchpoint is catalyzed by the magnesium chelatase and is a highly regulated process. the corresponding product, magnesium protoporphyrin ix, has been proposed to play an important role as a signaling molecule implicated in plastid-to-nucleus communication. to get more informa ... | 2006 | 17135235 |
| tomato chlorotic mottle virus is a target of rna silencing but the presence of specific short interfering rnas does not guarantee resistance in transgenic plants. | tomato chlorotic mottle virus (tocmov) is a begomovirus found widespread in tomato fields in brazil. tocmov isolate ba-se1 (tocmov-[ba-se1]) was shown to trigger the plant rna silencing surveillance in different host plants and, coinciding with a decrease in viral dna levels, small interfering rnas (sirnas) specific to tocmov-[ba-se1] accumulated in infected plants. although not homogeneously distributed, the sirna population in both infected nicotiana benthamiana and tomato plants represented t ... | 2006 | 17135316 |
| tomato chlorotic mottle virus is a target of rna silencing but the presence of specific short interfering rnas does not guarantee resistance in transgenic plants. | tomato chlorotic mottle virus (tocmov) is a begomovirus found widespread in tomato fields in brazil. tocmov isolate ba-se1 (tocmov-[ba-se1]) was shown to trigger the plant rna silencing surveillance in different host plants and, coinciding with a decrease in viral dna levels, small interfering rnas (sirnas) specific to tocmov-[ba-se1] accumulated in infected plants. although not homogeneously distributed, the sirna population in both infected nicotiana benthamiana and tomato plants represented t ... | 2006 | 17135316 |
| the root endophytic fungus piriformospora indica requires host cell death for proliferation during mutualistic symbiosis with barley. | fungi of the recently defined order sebacinales (basidiomycota) are involved in a wide spectrum of mutualistic symbioses (including mycorrhizae) with various plants, thereby exhibiting a unique potential for biocontrol strategies. the axenically cultivable root endophyte piriformospora indica is a model organism of this fungal order. it is able to increase biomass and grain yield of crop plants. in barley, the endophyte induces local and systemic resistance to fungal diseases and to abiotic stre ... | 2006 | 17116870 |
| increased frequency of homologous recombination and t-dna integration in arabidopsis caf-1 mutants. | chromatin assembly factor 1 (caf-1) is involved in nucleo some assembly following dna replication and nucleotide excision repair. in arabidopsis thaliana, the three caf-1 subunits are encoded by fas1, fas2 and, most likely, msi1, respectively. in this study, we asked whether genomic stability is altered in fas1 and fas2 mutants that are lacking caf-1 activity. depletion of either subunit increased the frequency of somatic homologous recombination (hr) in planta approximately 40-fold. the frequen ... | 2006 | 17110925 |
| c2h2 zinc finger-set histone methyltransferase is a plant-specific chromatin modifier. | histone modification represents a universal mechanism for regulation of eukaryotic gene expression underlying diverse biological processes from neuronal gene expression in mammals to control of flowering in plants. in animal cells, these chromatin modifications are effected by well-defined multiprotein complexes containing specific histone-modifying activities. in plants, information about the composition of such co-repressor complexes is just beginning to emerge. here, we report that two arabid ... | 2006 | 17224141 |
| c2h2 zinc finger-set histone methyltransferase is a plant-specific chromatin modifier. | histone modification represents a universal mechanism for regulation of eukaryotic gene expression underlying diverse biological processes from neuronal gene expression in mammals to control of flowering in plants. in animal cells, these chromatin modifications are effected by well-defined multiprotein complexes containing specific histone-modifying activities. in plants, information about the composition of such co-repressor complexes is just beginning to emerge. here, we report that two arabid ... | 2006 | 17224141 |
| a single chromoprotein with triple chromophores acts as both a phytochrome and a phototropin. | plants sense their environmental light conditions by using three photoreceptors that absorb in the uv, blue/near uv, and red/far-red spectral ranges. these photoreceptors have specific chromophore components corresponding to their absorption spectra. phytochrome, a red/far-red light receptor, has phytochromobilin as its chromophore, whereas the blue/near uv photoreceptors cryptochrome and phototropin have a pair of flavin derivatives. plants use these various photoreceptors to assess the surroun ... | 2006 | 17093054 |
| a method for rapid similarity analysis of rna secondary structures. | owing to the rapid expansion of rna structure databases in recent years, efficient methods for structure comparison are in demand for function prediction and evolutionary analysis. usually, the similarity of rna secondary structures is evaluated based on tree models and dynamic programming algorithms. we present here a new method for the similarity analysis of rna secondary structures. | 2006 | 17090331 |
| the mechanism of gene targeting in physcomitrella patens: homologous recombination, concatenation and multiple integration. | the model bryophyte physcomitrella patens exhibits high frequencies of gene targeting when transformed with dna constructs containing sequences homologous with genomic loci. 'targeted gene replacement' (tgr) resulting from homologous recombination (hr) between each end of a targeting construct and the targeted locus occurs when either single or multiple targeting vectors are delivered. in the latter instance simultaneous, multiple, independent integration of different transgenes occurs at the ta ... | 2006 | 17090599 |
| two cytosolic glutamine synthetase isoforms of maize are specifically involved in the control of grain production. | the roles of two cytosolic maize glutamine synthetase isoenzymes (gs1), products of the gln1-3 and gln1-4 genes, were investigated by examining the impact of knockout mutations on kernel yield. in the gln1-3 and gln1-4 single mutants and the gln1-3 gln1-4 double mutant, gs mrna expression was impaired, resulting in reduced gs1 protein and activity. the gln1-4 phenotype displayed reduced kernel size and gln1-3 reduced kernel number, with both phenotypes displayed in gln1-3 gln1-4. however, at mat ... | 2006 | 17138698 |
| insights into nuclear organization in plants as revealed by the dynamic distribution of arabidopsis sr splicing factors. | serine/arginine-rich (sr) proteins are splicing regulators that share a modular structure consisting of one or two n-terminal rna recognition motif domains and a c-terminal rs-rich domain. we investigated the dynamic localization of the arabidopsis thaliana sr protein rszp22, which, as we showed previously, distributes in predominant speckle-like structures and in the nucleolus. to determine the role of rszp22 diverse domains in its nucleolar distribution, we investigated the subnuclear localiza ... | 2006 | 17114353 |
| snd1, a nac domain transcription factor, is a key regulator of secondary wall synthesis in fibers of arabidopsis. | secondary walls in fibers and tracheary elements constitute the most abundant biomass produced by plants. although a number of genes involved in the biosynthesis of secondary wall components have been characterized, little is known about the molecular mechanisms underlying the coordinated expression of these genes. here, we demonstrate that the arabidopsis thaliana nac (for nam, ataf1/2, and cuc2) domain transcription factor, snd1 (for secondary wall-associated nac domain protein), is a key tran ... | 2006 | 17114348 |
| siamese, a plant-specific cell cycle regulator, controls endoreplication onset in arabidopsis thaliana. | recessive mutations in the siamese (sim) gene of arabidopsis thaliana result in multicellular trichomes harboring individual nuclei with a low ploidy level, a phenotype strikingly different from that of wild-type trichomes, which are single cells with a nuclear dna content of approximately 16c to 32c. these observations suggested that sim is required to suppress mitosis as part of the switch to endoreplication in trichomes. here, we demonstrate that sim encodes a nuclear-localized 14-kd protein ... | 2006 | 17098811 |
| a membrane-bound nac transcription factor regulates cell division in arabidopsis. | controlled release of membrane-tethered, dormant precursors is an intriguing activation mechanism that regulates diverse cellular functions in eukaryotes. an exquisite example is the proteolytic activation of membrane-bound transcription factors. the proteolytic cleavage liberates active transcription factors from the membranes that can enter the nucleus and evokes rapid transcriptional responses to incoming stimuli. here, we show that a membrane-bound nac (for nam, ataf1/2, cuc2) transcription ... | 2006 | 17098812 |
| wax-deficient anther1 is involved in cuticle and wax production in rice anther walls and is required for pollen development. | in vegetative leaf tissues, cuticles including cuticular waxes are important for protection against nonstomatal water loss and pathogen infection as well as for adaptations to environmental stress. however, their roles in the anther wall are rarely studied. the innermost layer of the anther wall (the tapetum) is essential for generating male gametes. here, we report the characterization of a t-dna insertional mutant in the wax-deficient anther1 (wda1) gene of rice (oryza sativa), which shows sig ... | 2006 | 17138699 |
| the rice tapetum degeneration retardation gene is required for tapetum degradation and anther development. | in flowering plants, tapetum degeneration is proposed to be triggered by a programmed cell death (pcd) process during late stages of pollen development; the pcd is thought to provide cellular contents supporting pollen wall formation and to allow the subsequent pollen release. however, the molecular basis regulating tapetum pcd in plants remains poorly understood. we report the isolation and characterization of a rice (oryza sativa) male sterile mutant tapetum degeneration retardation (tdr), whi ... | 2006 | 17138695 |
| suppressor of frigida4, encoding a c2h2-type zinc finger protein, represses flowering by transcriptional activation of arabidopsis flowering locus c. | flowering locus c (flc), a strong floral repressor, is one of the central regulators of flowering in arabidopsis thaliana. the expression of flc is increased by frigida (fri) but decreased by vernalization, a long period of cold exposure that accelerates flowering. although many aspects of flc regulation have been reported, it is not known how flc is transcriptionally activated by fri at the molecular level. we isolated suppressor of frigida4 (suf4), a mutant that flowers early as a result of lo ... | 2006 | 17138694 |
| functional conservation of a root hair cell-specific cis-element in angiosperms with different root hair distribution patterns. | vascular plants develop distinctive root hair distribution patterns in the root epidermis, depending on the taxon. the three patterns, random (type 1), asymmetrical cell division (type 2), and positionally cued (type 3), are controlled by different upstream fate-determining factors that mediate expression of root hair cell-specific genes for hair morphogenesis. here, we address whether these root hair genes possess a common transcriptional regulatory module (cis-element) determining cell-type sp ... | 2006 | 17098810 |
| arabidopsis chromatin-associated hmga and hmgb use different nuclear targeting signals and display highly dynamic localization within the nucleus. | in plants, the chromatin-associated high mobility group (hmg) proteins occur in two subfamilies termed hmga and hmgb. the hmga proteins are characterized by the presence of four at-hook dna binding motifs, and the hmgb proteins contain an hmg box dna binding domain. as architectural factors, the hmg proteins appear to be involved in the regulation of transcription and other dna-dependent processes. we have examined the subcellular localization of arabidopsis thaliana hmga, hmgb1, and hmgb5, reve ... | 2006 | 17114349 |
| arabidopsis cup-shaped cotyledon3 regulates postembryonic shoot meristem and organ boundary formation. | overall shoot architecture in higher plants is highly dependent on the activity of embryonic and axillary shoot meristems, which are produced from the basal adaxial boundaries of cotyledons and leaves, respectively. in arabidopsis thaliana, redundant functions of the cup-shaped cotyledon genes cuc1, cuc2, and cuc3 regulate embryonic shoot meristem formation and cotyledon boundary specification. their functional importance and relationship in postembryonic development, however, is poorly understo ... | 2006 | 17122068 |
| light-induced expression of a myb gene regulates anthocyanin biosynthesis in red apples. | anthocyanins are secondary metabolites found in higher plants that contribute to the colors of flowers and fruits. in apples (malus domestica borkh.), several steps of the anthocyanin pathway are coordinately regulated, suggesting control by common transcription factors. a gene encoding an r2r3 myb transcription factor was isolated from apple (cv cripps' pink) and designated mdmyb1. analysis of the deduced amino acid sequence suggests that this gene encodes an ortholog of anthocyanin regulators ... | 2006 | 17012405 |
| glutamate:glyoxylate aminotransferase modulates amino acid content during photorespiration. | in photorespiration, peroxisomal glutamate:glyoxylate aminotransferase (ggat) catalyzes the reaction of glutamate and glyoxylate to produce 2-oxoglutarate and glycine. previous studies demonstrated that alanine aminotransferase-like protein functions as a photorespiratory ggat. photorespiratory transamination to glyoxylate, which is mediated by ggat and serine glyoxylate aminotransferase (sgat), is believed to play an important role in the biosynthesis and metabolism of major amino acids. to bet ... | 2006 | 16950862 |
| a negative regulatory role for auxin in sulphate deficiency response in arabidopsis thaliana. | sulphate is a major macronutrient required for the synthesis of the sulphur (s)-containing amino acid cysteine and thus is critical for cellular metabolism, growth and development and response to various abiotic and biotic stresses. a recent genome-wide expression study suggested that several auxin-inducible genes were up-regulated by s deficiency in arabidopsis. here, we examined the relationship between auxin signaling and s deficiency. investigation of dr5::gus expression patterns indicates t ... | 2006 | 17063378 |
| a negative regulatory role for auxin in sulphate deficiency response in arabidopsis thaliana. | sulphate is a major macronutrient required for the synthesis of the sulphur (s)-containing amino acid cysteine and thus is critical for cellular metabolism, growth and development and response to various abiotic and biotic stresses. a recent genome-wide expression study suggested that several auxin-inducible genes were up-regulated by s deficiency in arabidopsis. here, we examined the relationship between auxin signaling and s deficiency. investigation of dr5::gus expression patterns indicates t ... | 2006 | 17063378 |
| cloning of dog1, a quantitative trait locus controlling seed dormancy in arabidopsis. | genetic variation for seed dormancy in nature is a typical quantitative trait controlled by multiple loci on which environmental factors have a strong effect. finding the genes underlying dormancy quantitative trait loci is a major scientific challenge, which also has relevance for agriculture and ecology. in this study we describe the identification of the delay of germination 1 (dog1) gene previously identified as a quantitative trait locus involved in the control of seed dormancy. this gene w ... | 2006 | 17065317 |
| roles of arabidopsis atp/adp isopentenyltransferases and trna isopentenyltransferases in cytokinin biosynthesis. | cytokinins, which are central regulators of cell division and differentiation in plants, are adenine derivatives carrying an isopentenyl side chain that may be hydroxylated. plants have two classes of isopentenyltransferases (ipts) acting on the adenine moiety: atp/adp isopentenyltransferases (in arabidopsis thaliana, atipt1, 3, 4-8) and trna ipts (in arabidopsis, atipt2 and 9). atp/adp ipts are likely to be responsible for the bulk of cytokinin synthesis, whereas it is thought that cis-zeatin ( ... | 2006 | 17062755 |
| two-step recruitment of rna-directed dna methylation to tandem repeats. | tandem repeat sequences are frequently associated with gene silencing phenomena. the arabidopsis thaliana fwa gene contains two tandem repeats and is an efficient target for rna-directed de novo dna methylation when it is transformed into plants. we showed that the fwa tandem repeats are necessary and sufficient for de novo dna methylation and that repeated character rather than intrinsic sequence is likely important. endogenous fwa can adopt either of two stable epigenetic states: methylated an ... | 2006 | 17105345 |
| protein kinases and plant pores. | | 2006 | 20076480 |
| virion tails of beet yellows virus: coordinated assembly by three structural proteins. | filamentous virions of beet yellows virus contain a long body formed by a major capsid protein and a short tail that is assembled by a minor capsid protein (cpm), an hsp70-homolog (hsp70h), a 64-kda protein (p64), and a 20-kda protein (p20). using mutation analysis and newly developed in planta assays, here we investigate the genetic requirements for the tail assembly. we show that the inactivation of cpm dramatically reduces incorporation of both hsp70h and p64. furthermore, inactivation of hsp ... | 2006 | 17027895 |
| virion tails of beet yellows virus: coordinated assembly by three structural proteins. | filamentous virions of beet yellows virus contain a long body formed by a major capsid protein and a short tail that is assembled by a minor capsid protein (cpm), an hsp70-homolog (hsp70h), a 64-kda protein (p64), and a 20-kda protein (p20). using mutation analysis and newly developed in planta assays, here we investigate the genetic requirements for the tail assembly. we show that the inactivation of cpm dramatically reduces incorporation of both hsp70h and p64. furthermore, inactivation of hsp ... | 2006 | 17027895 |
| the arabidopsis suvr4 protein is a nucleolar histone methyltransferase with preference for monomethylated h3k9. | proteins containing the evolutionarily conserved set domain are involved in regulation of eukaryotic gene expression and chromatin structure through their histone lysine methyltransferase (hmtase) activity. the drosophila su(var)3-9 protein and related proteins of other organisms have been associated with gene repression and heterochromatinization. in arabidopsis there are 10 suvh and 5 suvr genes encoding proteins similar to su(var)3-9, and 4 suvh proteins have been shown to control heterochrom ... | 2006 | 17020925 |
| an arabidopsis glutathione peroxidase functions as both a redox transducer and a scavenger in abscisic acid and drought stress responses. | we isolated two t-dna insertion mutants of arabidopsis thaliana glutathione peroxidase3 (atgpx3) that exhibited a higher rate of water loss under drought stress, higher sensitivity to h(2)o(2) treatment during seed germination and seedling development, and enhanced production of h(2)o(2) in guard cells. by contrast, lines engineered to overexpress atgpx3 were less sensitive to drought stress than the wild type and displayed less transpirational water loss, which resulted in higher leaf surface t ... | 2006 | 16998070 |
| rapid transcriptome changes induced by cytosolic ca2+ transients reveal abre-related sequences as ca2+-responsive cis elements in arabidopsis. | the regulation of gene expression by cellular calcium is crucial for plant defense against biotic and abiotic stresses. however, the number of genes known to respond to specific transient calcium signals is limited, and as yet there is no definition of a calcium-responsive cis element in plants. here, we generated specific cytosolic calcium transients in intact arabidopsis thaliana seedlings and linked them to early transcriptome changes, followed by bioinformatic analysis of the responsive gene ... | 2006 | 16980540 |
| pdv1 and pdv2 mediate recruitment of the dynamin-related protein arc5 to the plastid division site. | during plastid division, the dynamin-related protein accumulation and replication of chloroplasts5 (arc5) is recruited from the cytosol to the surface of the outer chloroplast envelope membrane. in arabidopsis thaliana arc5 mutants, chloroplasts arrest during division site constriction. analysis of mutants similar to arc5 along with map-based cloning identified plastid division1 (pdv1), an integral outer envelope membrane protein, and its homolog pdv2 as components of the plastid division machin ... | 2006 | 16998069 |
| arabidopsis fama controls the final proliferation/differentiation switch during stomatal development. | coordination between cell proliferation and differentiation is essential to create organized and functional tissues. arabidopsis thaliana stomata are created through a stereotyped series of symmetric and asymmetric cell divisions whose frequency and orientation are informed by cell-cell interactions. receptor-like proteins and a mitogen-activated protein kinase kinase kinase were previously identified as negative regulators of stomatal development; here, we present the characterization of a bona ... | 2006 | 17088607 |
| rice plastidial n-glycosylated nucleotide pyrophosphatase/phosphodiesterase is transported from the er-golgi to the chloroplast through the secretory pathway. | a nucleotide pyrophosphatase/phosphodiesterase (npp) activity that catalyzes the hydrolytic breakdown of adp-glucose (adpg) has been shown to occur in the plastidial compartment of both mono- and dicotyledonous plants. to learn more about this enzyme, we purified two npps from rice (oryza sativa) and barley (hordeum vulgare) seedlings. both enzymes are glycosylated, since they bind to concanavalin a, stain with periodic acid-schiff reagent, and are digested by endo-h. a complete rice npp cdna, d ... | 2006 | 17028208 |
| arabidopsis carboxyl-terminal domain phosphatase-like isoforms share common catalytic and interaction domains but have distinct in planta functions. | an arabidopsis (arabidopsis thaliana) multigene family (predicted to be more than 20 members) encodes plant c-terminal domain (ctd) phosphatases that dephosphorylate ser residues in tandem heptad repeat sequences of the rna polymerase ii c terminus. ctd phosphatase-like (cpl) isoforms 1 and 3 are regulators of osmotic stress and abscisic acid (aba) signaling. evidence presented herein indicates that cpl3 and cpl4 are homologs of a prototype ctd phosphatase, fcp1 (tfiif-interacting ctd-phosphatas ... | 2006 | 16905668 |
| dual temporal role of plastid sigma factor 6 in arabidopsis development. | plants contain nuclear-coded sigma factors for initiation of chloroplast transcription. the in vivo function of individual members of the sigma gene family has become increasingly accessible by knockout and complementation strategies. here we have investigated plastid gene expression in an arabidopsis (arabidopsis thaliana) mutant with a defective gene for sigma factor 6. rna gel-blot hybridization and real-time reverse transcription polymerase chain reaction together indicate that this factor h ... | 2006 | 16905663 |
| characterization of synthetic hydroxyproline-rich proteoglycans with arabinogalactan protein and extensin motifs in arabidopsis. | a series of gene constructs encoding synthetic glycomodule peptides with n-terminal signal sequences and c-terminal green fluorescent proteins were expressed in transgenic arabidopsis (arabidopsis thaliana) under the control of the 35s promoter. the synthetic glycomodule peptides were composed of repetitive proline-containing motifs that have been previously found to be substrates for prolyl hydroxylases and subsequent o-glycosylation of the hydroxyproline residues. all of the constructs were se ... | 2006 | 16935991 |
| adenosine kinase modulates root gravitropism and cap morphogenesis in arabidopsis. | adenosine kinase (adk) is a key enzyme that regulates intra- and extracellular levels of adenosine, thereby modulating methyltransferase reactions, production of polyamines and secondary compounds, and cell signaling in animals. unfortunately, little is known about adk's contribution to the regulation of plant growth and development. here, we show that adk is a modulator of root cap morphogenesis and gravitropism. upon gravistimulation, soluble adk levels and activity increase in the root tip. m ... | 2006 | 16891550 |
| suppression of lx ribonuclease in tomato results in a delay of leaf senescence and abscission. | although present in different organisms and conserved in their protein sequence, the biological functions of t2 ribonucleases (rnase) are generally unknown. tomato (lycopersicon esculentum) lx is a t2/s-like rnase and its expression is known to be associated with phosphate starvation, ethylene responses, and senescence and programmed cell death. in this study, lx function was investigated using antisense tomato plants in which the lx protein level was reduced. lx protein levels normally become e ... | 2006 | 16920876 |
| dehydroascorbate reductase affects leaf growth, development, and function. | ascorbic acid (asc) is a major antioxidant in plants that detoxifies reactive oxygen species (ros) and maintains photosynthetic function. expression of dehydroascorbate reductase (dhar), responsible for regenerating asc from an oxidized state, regulates the cellular asc redox state, which in turn affects cell responsiveness and tolerance to environmental ros. because of its role in asc recycling, we examined whether dhar is important for plant growth. suppression of dhar expression resulted in a ... | 2006 | 16891549 |
| the turnip mutant of arabidopsis reveals that leafy cotyledon1 expression mediates the effects of auxin and sugars to promote embryonic cell identity. | the transition from embryonic to vegetative growth marks an important developmental stage in the plant life cycle. the turnip (tnp) mutant was identified in a screen for modifiers of polaris expression, a gene required for normal root growth. mapping and molecular characterization of tnp shows that it represents a gain-of-function mutant of leafy cotyledon1 (lec1), due to a promoter mutation. this results in the ectopic expression of lec1, but not of other lec genes, in vegetative tissues. the l ... | 2006 | 16935993 |
| the frequency and efficiency of endogene suppression by transitive silencing signals is influenced by the length of sequence homology. | transitivity, the spread of rna silencing along primary target sequences, leads to the degradation of secondary targets that have no sequence homology to the initial silencing trigger. we demonstrate that increasing the distance between direct and adjacent target sequences in a transgenic primary target delays the onset of silencing of a secondary target gene. silencing can spread in a 3' to 5' direction over a distance of at least 500 nucleotides (nt), but this requires consistently more time c ... | 2006 | 16891552 |
| immutans does not act as a stress-induced safety valve in the protection of the photosynthetic apparatus of arabidopsis during steady-state photosynthesis. | immutans (im) encodes a thylakoid membrane protein that has been hypothesized to act as a terminal oxidase that couples the reduction of o(2) to the oxidation of the plastoquinone (pq) pool of the photosynthetic electron transport chain. because im shares sequence similarity to the stress-induced mitochondrial alternative oxidase (aox), it has been suggested that the protein encoded by im acts as a safety valve during the generation of excess photosynthetically generated electrons. we combined i ... | 2006 | 16891546 |
| monoclonal antibodies from plants: a new speed record. | | 2006 | 17000998 |
| in planta transient expression as a system for genetic and biochemical analyses of chlorophyll biosynthesis. | mg chelatase is a multi-subunit enzyme that catalyses the first committed step of chlorophyll biosynthesis. studies in higher plants and algae indicate that the mg chelatase reaction product, mg-protoporphyrin ix plays an essential role in nuclear-plastid interactions. a number of mg chelatase mutants have been isolated from higher plants, including semi-dominant alleles of chli, the gene encoding the i subunit of the enzyme. to investigate the function of higher plant chli, bacterial orthologue ... | 2006 | 16953878 |
| altered expression of perk receptor kinases in arabidopsis leads to changes in growth and floral organ formation. | the proline-rich, extensin-like receptor kinase (perk) family is characterized by a putative extracellular domain related to cell wall proteins, followed by a transmembrane domain and kinase domain. the original member, perk1, was isolated from brassica napus (bnperk1) and 15 perk1-related members were subsequently identified in the arabidopsis thaliana genome. ectopic expression and antisense suppression studies were performed using the bnperk1 cdna under the control of the 35s camv constitutiv ... | 2006 | 19516986 |
| mitochondria-associated hexokinases play a role in the control of programmed cell death in nicotiana benthamiana. | recent findings suggest a pivotal role for mitochondria-associated hexokinase in the regulation of apoptosis in animal cells. in this study, virus-induced gene silencing (vigs) of a hexokinase-encoding hxk1 caused necrotic lesions on leaves, abnormal leaf morphology, and retarded plant growth in nicotiana benthamiana. hxk1 was associated with the mitochondria, and this association required the n-terminal membrane anchor. vigs of hxk1 reduced the cellular glucose-phosphorylating activity to appro ... | 2006 | 16920781 |
| overexpression of the arabidopsis syntaxin pep12/syp21 inhibits transport from the prevacuolar compartment to the lytic vacuole in vivo. | golgi-mediated transport to the lytic vacuole involves passage through the prevacuolar compartment (pvc), but little is known about how vacuolar proteins exit the pvc. we show that this last step is inhibited by overexpression of arabidopsis thaliana syntaxin pep12/syp21, causing an accumulation of soluble and membrane cargo and the plant vacuolar sorting receptor bp80 in the pvc. anterograde transport proceeds normally from the endoplasmic reticulum to the golgi and the pvc, although export fro ... | 2006 | 16935987 |
| rapid metabolism of glucose detected with fret glucose nanosensors in epidermal cells and intact roots of arabidopsis rna-silencing mutants. | genetically encoded glucose nanosensors have been used to measure steady state glucose levels in mammalian cytosol, nuclei, and endoplasmic reticulum. unfortunately, the same nanosensors in arabidopsis thaliana transformants manifested transgene silencing and undetectable fluorescence resonance energy transfer changes. expressing nanosensors in sgs3 and rdr6 transgene silencing mutants eliminated silencing and resulted in high fluorescence levels. to measure glucose changes over a wide range (na ... | 2006 | 16935985 |
| the balance between cell division and endoreplication depends on e2fc-dpb, transcription factors regulated by the ubiquitin-scfskp2a pathway in arabidopsis. | the balance between cell proliferation, cell cycle arrest, and differentiation needed to maintain the organogenetic program depends on the coordination of gene expression, posttranslational modification, and specific proteolysis of cell cycle regulators. the g1/s and g2/m transitions are critical checkpoints controlled, in part, by cyclin-dependent kinases in the retinoblastoma (rbr)/e2f/dp pathway. arabidopsis thaliana dpb is regulated by phosphorylation and targeted to proteasome-mediated prot ... | 2006 | 16920782 |
| interaction between rice mybga and the gibberellin response element controls tissue-specific sugar sensitivity of alpha-amylase genes. | expression of alpha-amylase genes during cereal grain germination and seedling growth is regulated negatively by sugar in embryos and positively by gibberellin (ga) in endosperm through the sugar response complex (src) and the ga response complex (garc), respectively. we analyzed two alpha-amylase promoters, alphaamy3 containing only src and alphaamy8 containing overlapped src and garc. alphaamy3 was sugar-sensitive but ga-nonresponsive in both rice (oryza sativa) embryos and endosperms, whereas ... | 2006 | 16905658 |
| down-regulation of endogenes mediated by a transitive silencing signal. | some rna silencing systems in plants, nematodes, and fungi show spreading of silencing along target sequences, termed transitive silencing. here, we address the question of whether endogenous targets can be silenced by a transitive silencing signal in plants. in transgenic arabidopsis thaliana plants that harbored a silencing-inducing locus and a transgenic chimeric primary target, silencing of a secondary transgenic target occurred and the expression of the endogenous catalase genes was down-re ... | 2006 | 16943416 |
| a shift of phloem unloading from symplasmic to apoplasmic pathway is involved in developmental onset of ripening in grape berry. | it remains unclear whether the phloem unloading pathway alters to adapt to developmental transition in fleshy fruits that accumulate high level of soluble sugars. using a combination of electron microscopy, transport of the phloem-mobile symplasmic tracer carboxyfluorescein, movement of the companion cell-expressed and the green fluorescent protein-tagged viral movement protein, and assays of the sucrose cleavage enzymes, the pathway of phloem unloading was studied in the berries of a hybrid gra ... | 2006 | 16861573 |
| ectopic expression of knotted1-like homeobox protein induces expression of cytokinin biosynthesis genes in rice. | some phytohormones such as gibberellins (gas) and cytokinins (cks) are potential targets of the knotted1-like homeobox (knox) protein. to enhance our understanding of knox protein function in plant development, we identified rice (oryza sativa) genes for adenosine phosphate isopentenyltransferase (ipt), which catalyzes the rate-limiting step of ck biosynthesis. molecular and biochemical studies revealed that there are eight ipt genes, osipt1 to osipt8, in the rice genome, including a pseudogene, ... | 2006 | 16861569 |
| genomic organization, differential expression, and interaction of squamosa promoter-binding-like transcription factors and microrna156 in rice. | transcription factors play essential roles in the developmental processes of plants. many such factors are regulated by micrornas (mirnas). squamosa (squa) promoter-binding-like (spl) genes encode plant-specific transcription factors, some of which contain complementary sequences of mirna156. in this study, 19 rice (oryza sativa) spl (osspl) genes and 12 rice mirna156 (osmir156) precursors were identified in the rice genome. sequence and experimental analysis suggested that 11 osspl genes were p ... | 2006 | 16861571 |
| disruption and overexpression of arabidopsis phytosulfokine receptor gene affects cellular longevity and potential for growth. | phytosulfokine (psk), a 5-amino acid sulfated peptide that has been identified in conditioned medium of plant cell cultures, promotes cellular growth in vitro via binding to the membrane-localized psk receptor. here, we report that loss-of-function and gain-of-function mutations of the arabidopsis (arabidopsis thaliana) psk receptor gene (atpskr1) alter cellular longevity and potential for growth without interfering with basic morphogenesis of plants. although mutant pskr1-1 plants exhibit morph ... | 2006 | 16829587 |