| an evolutionist visits the 43rd annual maize genetics conference. | | 2001 | 11402157 |
| antisense expression of a cell wall-associated protein kinase, wak4, inhibits cell elongation and alters morphology. | the arabidopsis cell wall-associated receptor-like kinase (wak) gene family contains five highly related members whose products are suited for exchanging signals between the intracellular and extracellular compartments. wak members are expressed in specific organs and regulated differentially by various biotic and abiotic factors. to gain further insight into how waks function during development, we used a glucocorticoid-inducible system to express ectopically the wak4 antisense gene. the induce ... | 2001 | 11402163 |
| early flowering3 encodes a novel protein that regulates circadian clock function and flowering in arabidopsis. | higher plants use photoperiodic cues to regulate many aspects of development, including the transition from vegetative to floral development. the early flowering3 (elf3) gene is required for photoperiodic flowering and normal circadian regulation in arabidopsis. we have cloned elf3 by positional methods and found that it encodes a novel 695-amino acid protein that may function as a transcriptional regulator. elf3 transcript level is regulated in a circadian manner, as is expected of a zeitnehmer ... | 2001 | 11402160 |
| adf proteins are involved in the control of flowering and regulate f-actin organization, cell expansion, and organ growth in arabidopsis. | based mostly on the results of in vitro experiments, adf (actin-depolymerizing factor) proteins are thought to be key modulators of the dynamic organization of the actin cytoskeleton. the few studies concerned with the in vivo function of adf proteins that have been reported to date were performed almost exclusively using single-cell systems and have failed to produce consistent results. to investigate adf functions in vivo and during the development of multicellular organs, we generated transge ... | 2001 | 11402164 |
| fpa, a gene involved in floral induction in arabidopsis, encodes a protein containing rna-recognition motifs. | fpa is a gene that regulates flowering time in arabidopsis via a pathway that is independent of daylength (the autonomous pathway). mutations in fpa result in extremely delayed flowering. fpa was identified by means of positional cloning. the predicted fpa protein contains three rna recognition motifs in the n-terminal region. fpa is expressed most strongly in developing tissues, similar to the expression of fca and luminidependens, two components of the autonomous pathway previously identified. ... | 2001 | 11402170 |
| proliferating cell nuclear antigen transcription is repressed through an e2f consensus element and activated by geminivirus infection in mature leaves. | the geminivirus tomato golden mosaic virus (tgmv) amplifies its dna genome in differentiated plant cells that lack detectable levels of dna replication enzymes. earlier studies showed that tgmv induces the accumulation of proliferating cell nuclear antigen (pcna), the processivity factor for dna polymerase delta, in mature cells of nicotiana benthamiana. we sought to determine if pcna protein accumulation reflects transcriptional activation of the host gene. rna gel blot analysis detected an app ... | 2001 | 11402171 |
| elf3 modulates resetting of the circadian clock in arabidopsis. | the arabidopsis early flowering 3 (elf3) mutation causes arrhythmic circadian output in continuous light, but there is some evidence of clock function in darkness. here, we show conclusively that normal circadian function occurs with no alteration of period length in elf3 mutants in dark conditions and that the light-dependent arrhythmia observed in elf3 mutants is pleiotropic on multiple outputs normally expressed at different times of day. plants overexpressing elf3 have an increased period le ... | 2001 | 11402162 |
| seed-specific over-expression of an arabidopsis cdna encoding a diacylglycerol acyltransferase enhances seed oil content and seed weight. | we recently reported the cloning and characterization of an arabidopsis (ecotype columbia) diacylglycerol acyltransferase cdna (zou et al., 1999) and found that in arabidopsis mutant line as11, an ethyl methanesulfonate-induced mutation at a locus on chromosome ii designated as tag1 consists of a 147-bp insertion in the dna, which results in a repeat of the 81-bp exon 2 in the tag1 cdna. this insertion mutation is correlated with an altered seed fatty acid composition, reduced diacylglycerol acy ... | 2001 | 11402213 |
| transgenic arabidopsis plants with decreased activity of fructose-6-phosphate,2-kinase/fructose-2,6-bisphosphatase have altered carbon partitioning. | the role of fructose-2,6-bisphosphate (fru-2,6-p(2)) as a regulatory metabolite in photosynthetic carbohydrate metabolism was studied in transgenic arabidopsis plants with reduced activity of fru-6-phosphate,2-kinase/fru-2,6-bisphosphatase. a positive correlation was observed between the fru-6-phosphate,2-kinase activity and the level of fru-2,6-p(2) in the leaves. the partitioning of carbon was studied by (14)co(2) labeling of photosynthetic products. plant lines with fru-2,6-p(2) levels down t ... | 2001 | 11402203 |
| the arabidopsis embryo mutant schlepperless has a defect in the chaperonin-60alpha gene. | we identified a t-dna-generated mutation in the chaperonin-60alpha gene of arabidopsis that produces a defect in embryo development. the mutation, termed schlepperless (slp), causes retardation of embryo development before the heart stage, even though embryo morphology remains normal. beyond the heart stage, the slp mutation results in defective embryos with highly reduced cotyledons. slp embryos exhibit a normal apical-basal pattern and radial tissue organization, but they are morphologically r ... | 2001 | 11402200 |
| the rop gtpase switch controls multiple developmental processes in arabidopsis. | g proteins are universal molecular switches in eukaryotic signal transduction. the arabidopsis genome sequence reveals no ras small gtpase and only one or a few heterotrimeric g proteins, two predominant classes of signaling g proteins found in animals. in contrast, arabidopsis possesses a unique family of 11 rop gtpases that belong to the rho family of small gtpases. previous studies indicate that rop controls actin-dependent pollen tube growth and h(2)o(2)-dependent defense responses. in this ... | 2001 | 11402196 |
| the heme-oxygenase family required for phytochrome chromophore biosynthesis is necessary for proper photomorphogenesis in higher plants. | the committed step in the biosynthesis of the phytochrome chromophore phytochromobilin involves the oxidative cleavage of heme by a heme oxygenase (ho) to form biliverdin ixalpha. through positional cloning of the photomorphogenic mutant hy1, the arabidopsis ho (designated atho1) responsible for much of phytochromobilin synthesis recently was identified. using the atho1 sequence, we identified families of ho genes in a number of plants that cluster into two subfamilies (ho1- and ho2-like). the t ... | 2001 | 11402195 |
| the arabidopsis athb-8 hd-zip protein acts as a differentiation-promoting transcription factor of the vascular meristems. | athb-8, -9, -14, -15, and ifl1/rev are members of a small homeodomain-leucine zipper family whose genes are characterized by expression in the vascular tissue. athb-8, a gene positively regulated by auxin (baima et al., 1995), is considered an early marker of the procambial cells and of the cambium during vascular regeneration after wounding. here, we demonstrate that although the formation of the vascular system is not affected in athb8 mutants, ectopic expression of athb-8 in arabidopsis plant ... | 2001 | 11402194 |
| atcsld3, a cellulose synthase-like gene important for root hair growth in arabidopsis. | a member of the cellulose synthase-like (subfamily d) gene family of arabidopsis, atcsld3, has been identified by t-dna tagging. the analysis of the corresponding mutant, csld3-1, showed that the atcsld3 gene plays a role in root hair growth in plants. root hairs grow in phases: first a bulge is formed and then the root hair elongates by polarized growth, the so-called "tip growth." in the mutant, root hairs were initiated at the correct position and grew into a bulge, but their elongation was s ... | 2001 | 11402188 |
| the biological functions of glutathione revisited in arabidopsis transgenic plants with altered glutathione levels. | a functional analysis of the role of glutathione in protecting plants from environmental stress was undertaken by studying arabidopsis that had been genetically modified to have altered glutathione levels. the steady-state glutathione concentration in arabidopsis plants was modified by expressing the cdna for gamma-glutamyl-cysteine synthetase (gsh1) in both the sense and antisense orientation. the resulting plants had glutathione levels that ranged between 3% and 200% of the level in wild-type ... | 2001 | 11402187 |
| the chimeric leucine-rich repeat/extensin cell wall protein lrx1 is required for root hair morphogenesis in arabidopsis thaliana. | in plants, the cell wall is a major determinant of cell morphogenesis. cell enlargement depends on the tightly regulated expansion of the wall, which surrounds each cell. however, the qualitative and quantitative mechanisms controlling cell wall enlargement are still poorly understood. here, we report the molecular and functional characterization of lrx1, a new arabidopsis gene that encodes a chimeric leucine-rich repeat/extensin protein. lrx1 is expressed in root hair cells and the protein is s ... | 2001 | 11331608 |
| arabidopsis plc1 is required for secondary responses to abscisic acid signals. | the role of inositol 1,4,5-trisphosphate (ins[1,4,5]p3) in transducing the abscisic acid (aba) signal during seed germination and in the stress responses of mature plants is poorly understood. we have considered the contributions of the phospholipase c1 (encoded by atplc1) and an ins(1,4,5)p3 5-phosphatase (encoded by atip5pii) to aba signaling by using a modified version of the glucocorticoid-inducible system to regulate transgene expression. in the presence of the dexamethasone (dex) inducer, ... | 2001 | 11340187 |
| identification of arabidopsis histone deacetylase hda6 mutants that affect transgene expression. | a mutant screen was conducted in arabidopsis that was based on deregulated expression of auxin-responsive transgenes. two different tightly regulated (i.e., very low expression in the absence of auxin treatment and very high expression after exogenous auxin treatment) auxin-responsive promoters were used to drive the expression of both a beta-glucuronidase (gus) reporter gene and a hygromycin phosphotransferase (hph)-selectable marker gene. this screen yielded several mutants, and five of the mu ... | 2001 | 11340181 |
| influence of kdel on the fate of trimeric or assembly-defective phaseolin: selective use of an alternative route to vacuoles. | the tetrapeptide kdel is commonly found at the c terminus of soluble proteins of the endoplasmic reticulum (er), and it contributes to their localization by interacting with a receptor that recycles between the golgi complex and the er. we investigated the effects of the addition of kdel to phaseolin, a protein normally delivered from the er to storage vacuoles via the golgi complex. we show that kdel prevents acquisition of trans-golgi-specific glycan modifications and causes interactions with ... | 2001 | 11340185 |
| the arabidopsis mutant cev1 has constitutively active jasmonate and ethylene signal pathways and enhanced resistance to pathogens. | jasmonates (jas) inhibit plant growth and induce plant defense responses. to define genes in the arabidopsis ja signal pathway, we screened for mutants with constitutive expression of a luciferase reporter for the ja-responsive promoter from the vegetative storage protein gene vsp1. one mutant, named constitutive expression of vsp1 (cev1), produced plants that were smaller than wild type, had stunted roots with long root hairs, accumulated anthocyanin, had constitutive expression of the defense- ... | 2001 | 11340179 |
| slender rice, a constitutive gibberellin response mutant, is caused by a null mutation of the slr1 gene, an ortholog of the height-regulating gene gai/rga/rht/d8. | the rice slender mutant (slr1-1) is caused by a single recessive mutation and results in a constitutive gibberellin (ga) response phenotype. the mutant elongates as if saturated with gas. in this mutant, (1) elongation was unaffected by an inhibitor of ga biosynthesis, (2) ga-inducible alpha-amylase was produced by the aleurone layers without gibberellic acid application, and (3) endogenous ga content was lower than in the wild-type plant. these results indicate that the product of the slr1 gene ... | 2001 | 11340177 |
| phytochrome-mediated photoperiod perception, shoot growth, glutamine, calcium, and protein phosphorylation influence the activity of the poplar bark storage protein gene promoter (bspa). | in poplars (populus), bspa encodes a 32-kd bark storage protein that accumulates in the inner bark of plants exposed to either short-day (sd) photoperiods or elevated levels of nitrogen. in this study, poplars transformed with a chimeric gene consisting of the bspa promoter fused to beta-glucuronidase (uida) were used to investigate the transcriptional regulation of the bspa promoter. photoperiodic activation of the bspa promoter was shown to involve perception by phytochrome and likely involves ... | 2001 | 11351097 |
| regulation of flowering in arabidopsis by an flc homologue. | the arabidopsis flc gene encodes a mads domain protein that acts as a repressor of flowering. late-flowering vernalization-responsive ecotypes and mutants have high steady-state levels of flc transcript, which decrease during the promotion of flowering by vernalization. therefore, flc has a central role in regulating the response to vernalization. we have isolated an arabidopsis gene, maf1, which encodes a protein that is closely related to flc. overexpression studies demonstrate that maf1 produ ... | 2001 | 11351076 |
| constitutive overexpression of cytosolic glutamine synthetase (gs1) gene in transgenic alfalfa demonstrates that gs1 may be regulated at the level of rna stability and protein turnover. | glutamine synthetase (gs) catalyzes the atp-dependent condensation of nh4+ with glutanate to yield glutamine. gene constructs consisting of the cauliflower mosaic virus (camv) 35s promoter driving a cytosolic isoform of gs (gs1) gene have been introduced into alfalfa (medicago sativa). although transcripts for the transgene were shown to accumulate to high levels in the leaves, they were undetectable in the nodules. however, significant amounts of beta-glucuronidase activity could be detected in ... | 2001 | 11351075 |
| green fluorescent protein is lighting up fungal biology. | | 2001 | 11319072 |
| a postgermination developmental arrest checkpoint is mediated by abscisic acid and requires the abi5 transcription factor in arabidopsis. | seed dormancy is a trait of considerable adaptive significance because it maximizes seedling survival by preventing premature germination under unfavorable conditions. understanding how seeds break dormancy and initiate growth is also of great agricultural and biotechnological interest. abscisic acid (aba) plays primary regulatory roles in the initiation and maintenance of seed dormancy. here we report that the basic leucine zipper transcription factor abi5 confers an enhanced response to exogen ... | 2001 | 11287670 |
| changes in root cap ph are required for the gravity response of the arabidopsis root. | although the columella cells of the root cap have been identified as the site of gravity perception, the cellular events that mediate gravity signaling remain poorly understood. to determine if cytoplasmic and/or wall ph mediates the initial stages of root gravitropism, we combined a novel cell wall ph sensor (a cellulose binding domain peptide-oregon green conjugate) and a cytoplasmic ph sensor (plants expressing ph-sensitive green fluorescent protein) to monitor ph dynamics throughout the grav ... | 2001 | 11283344 |
| a novel udp-glucose transferase is part of the callose synthase complex and interacts with phragmoplastin at the forming cell plate. | using phragmoplastin as a bait, we isolated an arabidopsis cdna encoding a novel udp-glucose transferase (ugt1). this interaction was confirmed by an in vitro protein--protein interaction assay using purified ugt1 and radiolabeled phragmoplastin. protein gel blot results revealed that ugt1 is associated with the membrane fraction and copurified with the product-entrapped callose synthase complex. these data suggest that ugt1 may act as a subunit of callose synthase that uses udp-glucose to synth ... | 2001 | 11283335 |
| the transparent testa12 gene of arabidopsis encodes a multidrug secondary transporter-like protein required for flavonoid sequestration in vacuoles of the seed coat endothelium. | phenolic compounds that are present in the testa interfere with the physiology of seed dormancy and germination. we isolated a recessive arabidopsis mutant with pale brown seeds, transparent testa12 (tt12), from a reduced seed dormancy screen. microscopic analysis of tt12 developing and mature testas revealed a strong reduction of proanthocyanidin deposition in vacuoles of endothelial cells. double mutants with tt12 and other testa pigmentation mutants were constructed, and their phenotypes conf ... | 2001 | 11283341 |
| possible role of root border cells in detection and avoidance of aluminum toxicity. | root border cells are living cells that surround root apices of most plant species and are involved in production of root exudates. we tested predictions of the hypothesis that they participate in detection and avoidance of aluminum (al) toxicity by comparing responses of two snapbean (phaseolus vulgaris) cultivars (cv dade and cv romano) known to differ in al resistance at the whole-root level. root border cells of these cultivars were killed by excess al in agarose gels or in simple salt solut ... | 2001 | 11299377 |
| isolation of a constans ortholog from pharbitis nil and its role in flowering. | the short-day plant pharbitis nil is a model plant for the study of photoperiodic control of floral initiation. flower formation can be induced at the cotyledon stage by a single long night of at least 14 h in duration. using differential display of mrna we identified a p. nil ortholog of the arabidopsis constans (co) gene, which will be referred to as pnco. expression of pnco was high after a 14-h night, but low when the dark period was 12 h or less. our results indicate that the level of the p ... | 2001 | 11299362 |
| mitogen-activated protein kinase phosphatase is required for genotoxic stress relief in arabidopsis. | genotoxic stress activates complex cellular responses allowing for the repair of dna damage and proper cell recovery. although plants are exposed constantly to increasing solar uv irradiation, the signaling cascades activated by genotoxic environments are largely unknown. we have identified an arabidopsis mutant (mkp1) hypersensitive to genotoxic stress treatments (uv-c and methyl methanesulphonate) due to disruption of a gene that encodes an arabidopsis homolog of mitogen-activated protein kina ... | 2001 | 11274055 |
| self-incompatibility in the genus arabidopsis: characterization of the s locus in the outcrossing a. lyrata and its autogamous relative a. thaliana. | as a starting point for a phylogenetic study of self-incompatibility (si) in crucifers and to elucidate the genetic basis of transitions between outcrossing and self-fertilizing mating systems in this family, we investigated the si system of arabidopsis lyrata. a. lyrata is an outcrossing close relative of the self-fertile a. thaliana and is thought to have diverged from a. thaliana approximately 5 million years ago and from brassica spp 15 to 20 million years ago. analysis of two s (sterility) ... | 2001 | 11251101 |
| a gain-of-function mutation in iaa28 suppresses lateral root development. | the phytohormone auxin is important in many aspects of plant development. we have isolated an auxin-resistant arabidopsis mutant, iaa28-1, that is severely defective in lateral root formation and that has diminished adult size and decreased apical dominance. the iaa28-1 mutant is resistant to inhibition of root elongation by auxin, cytokinin, and ethylene, but it responds normally to other phytohormones. we identified the gene defective in the iaa28-1 mutant by using a map-based positional appro ... | 2001 | 11251090 |
| lipoxygenase is involved in the control of potato tuber development. | plant lipoxygenases (loxs) are a functionally diverse class of dioxygenases implicated in physiological processes such as growth, senescence, and stress-related responses. loxs incorporate oxygen into their fatty acid substrates and produce hydroperoxide fatty acids that are precursors of jasmonic acid and related compounds. here, we report the involvement of the tuber-associated loxs, designated the lox1 class, in the control of tuber growth. rna hybridization analysis showed that the accumulat ... | 2001 | 11251100 |
| transposon-mediated single-copy gene delivery leads to increased transgene expression stability in barley. | instability of transgene expression in plants is often associated with complex multicopy patterns of transgene integration at the same locus, as well as position effects due to random integration. based on maize transposable elements activator (ac) and dissociation (ds), we developed a method to generate large numbers of transgenic barley (hordeum vulgare var golden promise) plants, each carrying a single transgene copy at different locations. plants expressing ac transposase (actpase) were cros ... | 2001 | 11244115 |
| wall-associated kinases are expressed throughout plant development and are required for cell expansion. | the mechanism by which events in the angiosperm cell wall are communicated to the cytoplasm is not well characterized. a family of five arabidopsis wall-associated kinases (waks) have the potential to provide a physical and signaling continuum between the cell wall and the cytoplasm. the waks have an active cytoplasmic protein kinase domain, span the plasma membrane, and contain an n terminus that binds the cell wall. we show here that waks are expressed at organ junctions, in shoot and root api ... | 2001 | 11226187 |
| identification of distinct specificity determinants in resistance protein cf-4 allows construction of a cf-9 mutant that confers recognition of avirulence protein avr4. | the tomato resistance genes cf-4 and cf-9 confer specific, hypersensitive response-associated recognition of cladosporium carrying the avirulence genes avr4 and avr9, respectively. cf-4 and cf-9 encode type i transmembrane proteins with extracellular leucine-rich repeats (lrrs). compared with cf-9, cf-4 lacks two lrrs and differs in 78 amino acid residues. to investigate the relevance of these differences for specificity, we exchanged domains between cf-4 and cf-9, and mutant constructs were tes ... | 2001 | 11226185 |
| petunia ap2-like genes and their role in flower and seed development. | we have isolated three apetala2 (ap2)-like genes from petunia and studied their expression patterns by in situ hybridization. phap2a has a high sequence similarity to the a function gene ap2 from arabidopsis and a similar expression pattern during flower development, suggesting that they are cognate orthologs. phap2b and phap2c encode for ap2-like proteins that belong to a different subgroup of the ap2 family of transcription factors and exhibit divergent, nearly complementary expression pattern ... | 2001 | 11226182 |
| cloning of an arabidopsis patatin-like gene, sturdy, by activation t-dna tagging. | activation t-dna tagging can generate dominant gain-of-function mutants by overexpression of a particular endogenous gene. we identified an activation-tagged mutant, sturdy, exhibiting a stiff inflorescence stem, thicker leaves, shorter siliques, larger seeds, round-shaped flowers, and delayed growth. it is most important that unlike its wild-type counterpart, this mutant is less prone to lodging. cloning of sturdy revealed that in sturdy, there is an open reading frame containing a single intro ... | 2001 | 11161015 |
| regulation of starch accumulation by granule-associated plant 14-3-3 proteins. | in higher plants the production of starch is orchestrated by chloroplast-localized biosynthetic enzymes, namely starch synthases, adp-glucose pyrophosphorylase, and starch branching and debranching enzymes. diurnal regulation of these enzymes, as well as starch-degrading enzymes, influences both the levels and composition of starch, and is dependent in some instances upon phosphorylation-linked regulation. the phosphoserine/threonine-binding 14-3-3 proteins participate in environmentally respons ... | 2001 | 11149942 |
| kojak encodes a cellulose synthase-like protein required for root hair cell morphogenesis in arabidopsis. | the cell wall is an important determinant of plant cell form. here we define a class of arabidopsis root hair mutants with defective cell walls. plants homozygous for kojak (kjk) mutations initiate root hairs that rupture at their tip soon after initiation. the kjk gene was isolated by positional cloning, and its identity was confirmed by the molecular complementation of the kjk(-) phenotype and the sequence of three kjk mutant alleles. kojak encodes a cellulose synthase-like protein, atcsld3. k ... | 2001 | 11156607 |
| downregulation of caffeic acid 3-o-methyltransferase and caffeoyl coa 3-o-methyltransferase in transgenic alfalfa. impacts on lignin structure and implications for the biosynthesis of g and s lignin. | transgenic alfalfa plants were generated harboring caffeic acid 3-o-methyltransferase (comt) and caffeoyl coa 3-o-methyltransferase (ccomt) cdna sequences under control of the bean phenylalanine ammonia-lyase pal2 promoter. strong downregulation of comt resulted in decreased lignin content, a reduction in total guaiacyl (g) lignin units, a near total loss of syringyl (s) units in monomeric and dimeric lignin degradation products, and appearance of low levels of 5-hydroxy guaiacyl units and a nov ... | 2001 | 11158530 |
| trh1 encodes a potassium transporter required for tip growth in arabidopsis root hairs. | root hair initiation involves the formation of a bulge at the basal end of the trichoblast by localized diffuse growth. tip growth occurs subsequently at this initiation site and is accompanied by the establishment of a polarized cytoplasmic organization. arabidopsis plants homozygous for a complete loss-of-function tiny root hair 1 (trh1) mutation were generated by means of the t-dna-tagging method. trichoblasts of trh1 plants form initiation sites but fail to undergo tip growth. a predicted pr ... | 2001 | 11158535 |
| canonical histidine kinase activity of the transmitter domain of the etr1 ethylene receptor from arabidopsis is not required for signal transmission. | ethylene signaling in plants is mediated by a family of receptors related to bacterial two-component histidine kinases. of the five members of the arabidopsis ethylene receptor family, members of subfamily i (etr1 and ers1) contain completely conserved histidine kinase domains, whereas members of subfamily ii (etr2, ein4, and ers2) lack conserved residues thought to be necessary for kinase activity. to examine the role of the conserved histidine kinase domain in receptor signaling, ers1;etr1 los ... | 2002 | 12509505 |
| canonical histidine kinase activity of the transmitter domain of the etr1 ethylene receptor from arabidopsis is not required for signal transmission. | ethylene signaling in plants is mediated by a family of receptors related to bacterial two-component histidine kinases. of the five members of the arabidopsis ethylene receptor family, members of subfamily i (etr1 and ers1) contain completely conserved histidine kinase domains, whereas members of subfamily ii (etr2, ein4, and ers2) lack conserved residues thought to be necessary for kinase activity. to examine the role of the conserved histidine kinase domain in receptor signaling, ers1;etr1 los ... | 2002 | 12509505 |
| increased level of hemoglobin 1 enhances survival of hypoxic stress and promotes early growth in arabidopsis thaliana. | overexpression of a class 1 hb (glb1) protects arabidopsis thaliana plants from the effects of severe hypoxia. overexpression of the bifunctional symbiotic hb (glb1s) from parasponia andersonii in a. thaliana also increases survival after hypoxia. plants overexpressing the hb 1 protein, mutated to have a low oxygen affinity, are as susceptible to hypoxia as wt plants, suggesting that the protection against hypoxia depends on the ability of the hb to bind ligands, such as oxygen, with high affini ... | 2002 | 12486248 |
| essential role of the g-domain in targeting of the protein import receptor attoc159 to the chloroplast outer membrane. | two homologous gtp-binding proteins, attoc33 and attoc159, control access of cytosolic precursor proteins to the chloroplast. attoc33 is a constitutive outer chloroplast membrane protein, whereas the precursor receptor attoc159 also exists in a soluble, cytosolic form. this suggests that attoc159 may be able to switch between a soluble and an integral membrane form. by transient expression of gfp fusion proteins, mutant analysis, and biochemical experimentation, we demonstrate that the gtp-bindi ... | 2002 | 12460988 |
| aequorin-based measurements of intracellular ca2+-signatures in plant cells. | due to the involvement of calcium as a main second messenger in the plant signaling pathway, increasing interest has been focused on the calcium signatures supposed to be involved in the patterning of the specific response associated to a given stimulus. in order to follow these signatures we described here the practical approach to use the non-invasive method based on the aequorin technology. besides reviewing the advantages and disadvantages of this method we report on results showing the usef ... | 2002 | 12734562 |
| t-dna integration into the arabidopsis genome depends on sequences of pre-insertion sites. | a statistical analysis of 9000 flanking sequence tags characterizing transferred dna (t-dna) transformants in arabidopsis sheds new light on t-dna insertion by illegitimate recombination. t-dna integration is favoured in plant dna regions with an a-t-rich content. the formation of a short dna duplex between the host dna and the left end of the t-dna sets the frame for the recombination. the sequence immediately downstream of the plant a-t-rich region is the master element for setting up the dna ... | 2002 | 12446565 |
| trp-dependent auxin biosynthesis in arabidopsis: involvement of cytochrome p450s cyp79b2 and cyp79b3. | the plant hormone auxin regulates many aspects of plant growth and development. although several auxin biosynthetic pathways have been proposed, none of these pathways has been precisely defined at the molecular level. here we provide in planta evidence that the two arabidopsis cytochrome p450s, cyp79b2 and cyp79b3, which convert tryptophan (trp) to indole-3-acetaldoxime (iaox) in vitro, are critical enzymes in auxin biosynthesis in vivo. iaox is thus implicated as an important intermediate in a ... | 2002 | 12464638 |
| plasma membrane aquaporins play a significant role during recovery from water deficit. | the role of plasma membrane aquaporins (pips) in water relations of arabidopsis was studied by examining plants with reduced expression of pip1 and pip2 aquaporins, produced by crossing two different antisense lines. compared with controls, the double antisense (das) plants had reduced amounts of pip1 and pip2 aquaporins, and the osmotic hydraulic conductivity of isolated root and leaf protoplasts was reduced 5- to 30-fold. the das plants had a 3-fold decrease in the root hydraulic conductivity ... | 2002 | 12481094 |
| molecular characterization of a novel gene family encoding act domain repeat proteins in arabidopsis. | in bacteria, the regulatory act domains serve as amino acid-binding sites in some feedback-regulated amino acid metabolic enzymes. we have identified a novel type of act domain-containing protein family in arabidopsis whose members contain act domain repeats (the "acr" protein family). there are at least eight acr genes located on each of the five chromosomes in the arabidopsis genome. gene structure comparisons indicate that the acr gene family may have arisen by gene duplications. northern-blo ... | 2002 | 12481063 |
| down-regulation of caffeic acid o-methyltransferase in maize revisited using a transgenic approach. | transgenic maize (zea mays) plants were generated with a construct harboring a maize caffeic acid o-methyltransferase (comt) cdna in the antisense (as) orientation under the control of the maize adh1 (alcohol dehydrogenase) promoter. adh1-driven beta-glucuronidase expression was localized in vascular tissues and lignifying sclerenchyma, indicating its suitability in transgenic experiments aimed at modifying lignin content and composition. one line of as plants, comt-as, displayed a significant r ... | 2002 | 12481050 |
| t-dna insertional mutagenesis for activation tagging in rice. | we have developed a new t-dna vector, pga2715, which can be used for promoter trapping and activation tagging of rice (oryza sativa) genes. the binary vector contains the promoterless beta-glucuronidase (gus) reporter gene next to the right border. in addition, the multimerized transcriptional enhancers from the cauliflower mosaic virus 35s promoter are located next to the left border. a total of 13,450 t-dna insertional lines have been generated using pga2715. histochemical gus assays have reve ... | 2002 | 12481047 |
| regulation of root hair initiation and expansin gene expression in arabidopsis. | the expression of two arabidopsis expansin genes (atexp7 and atexp18) is tightly linked to root hair initiation; thus, the regulation of these genes was studied to elucidate how developmental, hormonal, and environmental factors orchestrate root hair formation. exogenous ethylene and auxin, as well as separation of the root from the medium, stimulated root hair formation and the expression of these expansin genes. the effects of exogenous auxin and root separation on root hair formation required ... | 2002 | 12468740 |
| two e2f elements regulate the proliferating cell nuclear antigen promoter differently during leaf development. | e2f transcription factors regulate genes expressed at the g1/s boundary of the cell division cycle in higher eukaryotes. although animal e2f proteins and their target promoters have been studied extensively, little is known about how these factors regulate plant promoters. an earlier study identified two e2f consensus binding sites in the promoter of a nicotiana benthamiana gene encoding proliferating cell nuclear antigen (pcna) and showed that the proximal element (e2f2) is required for the ful ... | 2002 | 12468739 |
| abscisic acid-induced transcription is mediated by phosphorylation of an abscisic acid response element binding factor, trab1. | the rice basic domain/leu zipper factor trab1 binds to abscisic acid (aba) response elements and mediates aba signals to activate transcription. we show that trab1 is phosphorylated rapidly in an in vivo labeling experiment and by phosphatase-sensitive mobility shifts on sds-polyacrylamide gels. we had shown previously that a chimeric promoter containing gal4 binding sites became aba inducible when a gal4 binding domain-trab1 fusion protein was present. this expression system allowed us to assay ... | 2002 | 12468735 |
| gibberellins are required for seed development and pollen tube growth in arabidopsis. | gibberellins (gas) are tetracyclic diterpenoids that are essential endogenous regulators of plant growth and development. ga levels within the plant are regulated by a homeostatic mechanism that includes changes in the expression of a family of ga-inactivating enzymes known as ga 2-oxidases. ectopic expression of a pea ga 2-oxidase2 cdna caused seed abortion in arabidopsis, extending and confirming previous observations obtained with ga-deficient mutants of pea, suggesting that gas have an essen ... | 2002 | 12468732 |
| a kinesin-like protein is essential for oriented deposition of cellulose microfibrils and cell wall strength. | cortical microtubules have long been hypothesized to regulate the oriented deposition of cellulose microfibrils. however, the molecular mechanisms of how microtubules direct the orientation of cellulose microfibril deposition are not known. we have used fibers in the inflorescence stems of arabidopsis to study secondary wall deposition and cell wall strength and found a fragile fiber (fra1) mutant with a dramatic reduction in the mechanical strength of fibers. the fra1 mutation did not cause any ... | 2002 | 12468730 |
| arabidopsis ost1 protein kinase mediates the regulation of stomatal aperture by abscisic acid and acts upstream of reactive oxygen species production. | during drought, the plant hormone abscisic acid (aba) triggers stomatal closure, thus reducing water loss. using infrared thermography, we isolated two allelic arabidopsis mutants (ost1-1 and ost1-2) impaired in the ability to limit their transpiration upon drought. these recessive ost1 mutations disrupted aba induction of stomatal closure as well as aba inhibition of light-induced stomatal opening. by contrast, the ost1 mutations did not affect stomatal regulation by light or co(2), suggesting ... | 2002 | 12468729 |
| arabidopsis e2fc functions in cell division and is degraded by the ubiquitin-scf(atskp2) pathway in response to light. | selective ubiquitin-mediated proteolysis through the cell cycle controls the availability, and therefore the activity, of several cell proliferation proteins. e2f transcription factors play distinct roles in both proliferating and differentiated cells by regulating gene expression. here, we report that arabidopsis ate2fc is regulated by a balance between gene expression and ubiquitin-proteasome proteolysis. ate2fc degradation implicates the function of the e3 ubiquitin-ligase skp1, cullin, f-box ... | 2002 | 12468727 |
| a phytochrome-associated protein phosphatase 2a modulates light signals in flowering time control in arabidopsis. | reversible protein phosphorylation, which is catalyzed by functionally coupled protein kinases and protein phosphatases, is a major signaling mechanism in eukaryotic cellular functions. the red and far-red light-absorbing phytochrome photoreceptors are light-regulated ser/thr-specific protein kinases that regulate diverse photomorphogenic processes in plants. here, we demonstrate that the phytochromes functionally interact with the catalytic subunit of a ser/thr-specific protein phosphatase 2a d ... | 2002 | 12468726 |
| regulation of axis determinacy by the arabidopsis pinhead gene. | plants produce proximal-distal growth axes with two types of growth potential: they can be indeterminate, in which case growth continues indefinitely, or they can be determinate, in which case growth is limited to the production of a single organ or a discrete set of organs. the indeterminate shoot axes of arabidopsis pinhead/zwille mutants frequently are transformed to a determinate state. pinhead (pnh) is expressed in the central domain of the developing plant: the provascular tissue, the shoo ... | 2002 | 12468725 |
| osm1/syp61: a syntaxin protein in arabidopsis controls abscisic acid-mediated and non-abscisic acid-mediated responses to abiotic stress. | to identify the genetic loci that control salt tolerance in higher plants, a large-scale screen was conducted with a bialaphos marker-based t-dna insertional collection of arabidopsis ecotype c24 mutants. one line, osm1 (for osmotic stress-sensitive mutant), exhibited increased sensitivity to both ionic (nacl) and nonionic (mannitol) osmotic stress in a root-bending assay. the osm1 mutant displayed a more branched root pattern with or without stress and was hypersensitive to inhibition by na(+), ... | 2002 | 12468724 |
| agamous-like 24, a dosage-dependent mediator of the flowering signals. | the most dramatic phase change in plants is the transition from vegetative to reproductive growth. this flowering process is regulated by several interacting pathways that monitor both the developmental state of the plants and environmental cues such as light and temperature. the flowering-time genes flowering locus t (ft) and suppressor of overexpression of co1 (soc1), together with the floral meristem identity gene leafy (lfy), are three essential regulators integrating floral signals from mul ... | 2002 | 12451184 |
| a pectin glucuronyltransferase gene is essential for intercellular attachment in the plant meristem. | intercellular attachment is an essential process in the morphogenesis of multicellular organisms. a unique mutant, nolac-h18 (nonorganogenic callus with loosely attached cells), generated by t-dna transformation using leaf-disk cultures of haploid nicotiana plumbaginifolia, lost the ability to form tight intercellular attachments and adventitious shoots. the gene tagged with t-dna, named npgut1 (glucuronyltransferase 1), was similar to the gene for the catalytic domains of animal glucuronyltrans ... | 2002 | 12451175 |
| mitogen-activated protein kinase signaling in postgermination arrest of development by abscisic acid. | abscisic acid (aba) mediates plant responses to environmental stress, particularly to water status. during germination, the embryo emerges from dormancy as the aba concentration declines. exposure to exogenous aba during germination arrests development rapidly, but reversibly, enabling seedlings to withstand early water stress without loss of viability. postgermination proteolytic degradation of the essential abi5 transcription factor is interrupted by perception of an increase in aba concentrat ... | 2002 | 12434021 |
| an arabidopsis histidine kinase is essential for megagametogenesis. | cytokinin-independent 1 (cki1) belongs to a group of putative plant histidine kinases whose members do not appear to act as ethylene receptors. the deduced protein structure, combined with the observation that arabidopsis callus cultures overexpressing cki1 exhibit a "cytokinin-independent" cell division and greening phenotype, led to the hypothesis that cki1 is involved in cytokinin signaling, perhaps acting as a cytokinin receptor. to test the function of cki1, we used a reverse-genetic approa ... | 2002 | 12426401 |
| psbs-dependent enhancement of feedback de-excitation protects photosystem ii from photoinhibition. | feedback de-excitation (qe) regulates light harvesting in plants to prevent inhibition of photosynthesis when light absorption exceeds photosynthetic capacity. although the mechanism of qe is not completely understood, it is known to require a low thylakoid lumen ph, de-epoxidized xanthophylls, and the photosystem ii protein psbs. during a short-term 4-h exposure to excess light, three psbs- and qe-deficient arabidopsis thaliana mutants that differed in xanthophyll composition were more photoinh ... | 2002 | 12417767 |
| the procambium specification gene oshox1 promotes polar auxin transport capacity and reduces its sensitivity toward inhibition. | the auxin-inducible homeobox gene oshox1 of rice (oryza sativa) is a positive regulator of procambial cell fate commitment, and its overexpression reduces the sensitivity of polar auxin transport (pat) to the pat inhibitor 1-n-naphthylphthalamic acid (npa). here, we show that wild-type rice leaves formed under conditions of pat inhibition display vein hypertrophy, reduced distance between longitudinal veins, and increased distance between transverse veins, providing experimental evidence for a r ... | 2002 | 12428000 |
| localization, ion channel regulation, and genetic interactions during abscisic acid signaling of the nuclear mrna cap-binding protein, abh1. | abscisic acid (aba) regulates developmental processes and abiotic stress responses in plants. we recently characterized a new arabidopsis mutant, abh1, which shows aba-hypersensitive regulation of seed germination, stomatal closing, and cytosolic calcium increases in guard cells (v. hugouvieux, j.m. kwak, j.i. schroeder [2001] cell 106: 477-487). abh1 encodes the large subunit of a dimeric arabidopsis mrna cap-binding complex and in expression profiling experiments was shown to affect mrna level ... | 2002 | 12427994 |
| lectr1, a tomato ctr1-like gene, demonstrates ethylene signaling ability in arabidopsis and novel expression patterns in tomato. | lectr1 was initially isolated by both differential display reverse transcriptase-polymerase chain reaction screening for tomato (lycopersicon esculentum) fruit ethylene-inducible genes and through homology with the arabidopsis ctr1 cdna. lectr1 shares strong nucleotide sequence homology with arabidopsis ctr1, a gene acting downstream of the ethylene receptor and showing similarity to the raf family of serine/threonine protein kinases. the length of the lectr1 transcribed region from atg to stop ... | 2002 | 12427980 |
| inducible dna demethylation mediated by the maize suppressor-mutator transposon-encoded tnpa protein. | heritable epigenetic inactivation of the maize suppressor-mutator (spm) transposon is associated with promoter methylation, and its reversal is mediated by the transposon-encoded tnpa protein. we have developed an assay that permits demethylation of the spm sequence to be controlled by inducing the expression of tnpa in plant cells. using this assay, we show that demethylation is a rapid, active process. tnpa is a weak transcriptional activator, and deletions that abolish its transcriptional act ... | 2002 | 12417708 |
| atopt3, a member of the oligopeptide transporter family, is essential for embryo development in arabidopsis. | a t-dna-tagged population of arabidopsis was screened for mutations in atopt3, which encodes a member of the oligopeptide (opt) family of peptide transporters, and a recessive mutant allele, opt3, was identified. phenotypic analysis of opt3 showed that most homozygous embryos were arrested at or before the octant stage of embryo development and that none showed the usual periclinal division leading to the formation of the protoderm. this defective phenotype could be reversed by complementation w ... | 2002 | 12417702 |
| global and hormone-induced gene expression changes during shoot development in arabidopsis. | a global analysis of gene expression events during shoot development in arabidopsis was conducted using oligonucleotide array analysis. shoots can be induced in tissue culture by preincubating root explants on an auxin-rich callus induction medium (cim) and by transferring explants to a cytokinin-rich shoot induction medium (sim), during which time explants become committed to shoot formation and ultimately form shoots. oligonucleotide array data obtained during shoot development from approximat ... | 2002 | 12417700 |
| a unique short-chain dehydrogenase/reductase in arabidopsis glucose signaling and abscisic acid biosynthesis and functions. | glc has hormone-like functions and controls many vital processes through mostly unknown mechanisms in plants. we report here on the molecular cloning of glucose insensitive1 (gin1) and abscisic acid deficient2 (aba2) which encodes a unique arabidopsis short-chain dehydrogenase/reductase (sdr1) that functions as a molecular link between nutrient signaling and plant hormone biosynthesis. sdr1 is related to sdr superfamily members involved in retinoid and steroid hormone biosynthesis in mammals and ... | 2002 | 12417697 |
| vh1, a provascular cell-specific receptor kinase that influences leaf cell patterns in arabidopsis. | the formation of the venation pattern in leaves is ideal for examining signaling pathways that recognize and respond to spatial and temporal information, because the pattern is two-dimensional and heritable and the resulting veins influence the three-dimensional spatial organization of the surrounding differentiating leaf cell types. we identified a provascular/procambial cell-specific gene that encodes a leu-rich repeat receptor kinase, which we named vascular highway1 (vh1). a change in the ex ... | 2002 | 12417696 |
| translational fusions with the engrailed repressor domain efficiently convert plant transcription factors into dominant-negative functions. | evidence is provided that plant transcription factors can be efficiently reprogrammed to dominant- negative functions by the use of a repressor domain of the engrailed (en) gene from drosophila. ectopic expression of translational fusions between the en(298) n-terminus and the complete coding regions of the shootmeristemless, apetala3, pistillata and knat1 transcription factors results in trans-dominant functions which phenocopy loss-of-function mutants. the combination of the dominant-negative ... | 2002 | 12409462 |
| a lotus basic leucine zipper protein with a ring-finger motif negatively regulates the developmental program of nodulation. | the developmental program of nodulation is regulated systemically in leguminous host species. a mutant astray (ljsym77) in lotus japonicus has lost some sort of its ability to regulate this symtem, and shows enhanced and early nodulation. in the absence of rhizobia, this mutant exhibits characteristics associated with defects in light and gravity responses. these nonsymbiotic phenotypes of astray are very similar to those observed in photomorphogenic arabidopsis mutant hy5. based on this evidenc ... | 2002 | 12397181 |
| mile-high view of plant biology. | a report on plant biology 2002, the annual meeting of the american society of plant biologists, denver, usa, 3-7 august 2002. | 2002 | 12429056 |
| bottlenecks for metabolic engineering of isoflavone glycoconjugates in arabidopsis. | in view of their perceived chemopreventive activities against hormone-dependent cancers, cardiovascular disease, and postmenopausal ailments, there is considerable interest in engineering plants to contain isoflavone phytoestrogens. however, attempts to date have only resulted in low levels of isoflavone accumulation in non-legumes. introducing soybean isoflavone synthase (ifs) into arabidopsis thaliana leads to accumulation of low levels of genistein glycosides. leaves of wild-type a. thaliana ... | 2002 | 12384577 |
| analyses of single-copy arabidopsis t-dna-transformed lines show that the presence of vector backbone sequences, short inverted repeats and dna methylation is not sufficient or necessary for the induction of transgene silencing. | in genetically transformed plants, transgene silencing has been correlated with multiple and complex insertions of foreign dna, e.g. t-dna and vector backbone sequences. occasionally, single-copy transgenes also suffer transgene silencing. we have compared integration patterns and t-dna/plant dna junctions in a collection of 37 single-copy t-dna-transformed arabidopsis lines, of which 13 displayed silencing. vector sequences were found integrated in five lines, but only one of these displayed si ... | 2002 | 12384603 |
| the tomato fer gene encoding a bhlh protein controls iron-uptake responses in roots. | iron deficiency is among the most common nutritional disorders in plants. to cope with low iron supply, plants with the exception of the gramineae increase the solubility and uptake of iron by inducing physiological and developmental alterations including iron reduction, soil acidification, fe(ii) transport and root-hair proliferation (strategy i). the chlorotic tomato fer mutant fails to activate the strategy i. it was shown previously that the fer gene is required in the root. here, we show th ... | 2002 | 12370409 |
| photorespiratory nh(4)(+) production in leaves of wild-type and glutamine synthetase 2 antisense oilseed rape. | exposure of oilseed rape (brassica napus) plants to increasing leaf temperatures between 15 degrees c and 25 degrees c increased photorespiratory nh(4)(+) production from 0.7 to 3.5 micromol m(-2) s(-1). despite the 5-fold increase in the rate of nh(4)(+) production, the nh(4)(+) concentration in root and leaf tissue water and xylem sap dropped significantly, whereas that in the leaf apoplastic fluid remained constant. the in vitro activity of glutamine synthetase (gs) in both leaves and roots a ... | 2002 | 12376662 |
| short integuments1/suspensor1/carpel factory, a dicer homolog, is a maternal effect gene required for embryo development in arabidopsis. | the importance of maternal cells in controlling early embryogenesis is well understood in animal development, yet in plants the precise role of maternal cells in embryogenesis is unclear. we demonstrated previously that maternal activity of the sin1 (short integuments1) gene of arabidopsis is essential for embryo pattern formation and viability, and that its postembryonic activity is required for several processes in reproductive development, including flowering time control and ovule morphogene ... | 2002 | 12376646 |
| transcriptional and posttranscriptional regulation of arabidopsis tch4 expression by diverse stimuli. roles of cis regions and brassinosteroids. | the arabidopsis tch4 gene is up-regulated in expression by diverse environmental and hormonal stimuli. because tch4 encodes a xyloglucan endotransglucosylase/hydrolase, this change in expression may reflect a recruitment of cell wall-modifying activity in response to environmental stress and growth. how diverse stimuli lead to the common response of tch4 expression regulation is not known. here, we show that induction of expression by the diverse stimuli of touch, darkness, cold, heat, and brass ... | 2002 | 12376643 |
| arabidopsis abi5 subfamily members have distinct dna-binding and transcriptional activities. | a small family of novel basic leucine zipper proteins that includes abscisic acid (aba)-insensitive 5 (abi5) binds to the promoter region of the lea class gene dc3. the factors, referred to as atdpbfs (arabidopsis dc3 promoter-binding factors), were isolated from an immature seed cdna library. atdpbfs bind to the embryo specification and aba-responsive elements in the dc3 promoter and are unique in that they can interact with cis-elements that do not contain the acgt core sequence required for t ... | 2002 | 12376636 |
| molecular characterization of the cotton ghtub1 gene that is preferentially expressed in fiber. | each fiber of cotton (gossypium hirsutum) is a single epidermal cell that rapidly elongates to 2.5 to 3.0 cm from the ovule surface within about 16 d after anthesis. a large number of genes are required for fiber differentiation and development, but so far, little is known about how these genes control and regulate the process of fiber development. to investigate gene expression patterns in fiber, a cdna, ghtub1, encoding beta-tubulin was isolated from a cotton fiber cdna library. the analyses o ... | 2002 | 12376634 |
| transcription factor cbf4 is a regulator of drought adaptation in arabidopsis. | in plants, low temperature and dehydration activate a set of genes containing c-repeat/dehydration-responsive elements in their promoter. it has been shown previously that the arabidopsis cbf/dreb1 transcription activators are critical regulators of gene expression in the signal transduction of cold acclimation. here, we report the isolation of an apparent homolog of the cbf/dreb1 proteins (cbf4) that plays the equivalent role during drought adaptation. in contrast to the three already identifie ... | 2002 | 12376631 |
| phase-specific circadian clock regulatory elements in arabidopsis. | we have defined a minimal arabidopsis catalase 3 (cat3) promoter sufficient to drive evening-specific circadian transcription of a luciferase reporter gene. deletion analysis and site-directed mutagenesis reveal a circadian response element, the evening element (ee: aaaatatct), that is necessary for evening-specific transcription. the ee differs only by a single base pair from the circadian clock associated 1-binding site (cbs: aaaaaatct), which is important for morning-specific transcription. w ... | 2002 | 12376630 |
| tomato plants ectopically expressing arabidopsis cbf1 show enhanced resistance to water deficit stress. | a dna cassette containing an arabidopsis c repeat/dehydration-responsive element binding factor 1 (cbf1) cdna and a nos terminator, driven by a cauliflower mosaic virus 35s promoter, was transformed into the tomato (lycopersicon esculentum) genome. these transgenic tomato plants were more resistant to water deficit stress than the wild-type plants. the transgenic plants exhibited growth retardation by showing dwarf phenotype, and the fruit and seed numbers and fresh weight of the transgenic toma ... | 2002 | 12376629 |
| down-regulation of tm29, a tomato sepallata homolog, causes parthenocarpic fruit development and floral reversion. | we have characterized the tomato (lycopersicon esculentum mill.) mads box gene tm29 that shared a high amino acid sequence homology to the arabidopsis sep1, 2, and 3 (sepallata1, 2, and 3) genes. tm29 showed similar expression profiles to sep1, with accumulation of mrna in the primordia of all four whorls of floral organs. in addition, tm29 mrna was detected in inflorescence and vegetative meristems. to understand tm29 function, we produced transgenic tomato plants in which tm29 expression was d ... | 2002 | 12376628 |
| genome-wide identification of nodule-specific transcripts in the model legume medicago truncatula. | the medicago truncatula expressed sequence tag (est) database (gene index) contains over 140,000 sequences from 30 cdna libraries. this resource offers the possibility of identifying previously uncharacterized genes and assessing the frequency and tissue specificity of their expression in silico. because m. truncatula forms symbiotic root nodules, unlike arabidopsis, this is a particularly important approach in investigating genes specific to nodule development and function in legumes. our analy ... | 2002 | 12376622 |
| multiple ubiquitin ligase-mediated processes require cop9 signalosome and axr1 function. | the cop9 signalosome (csn) is an evolutionarily conserved multiprotein complex that mediates the repression of photomorphogenesis in the dark in arabidopsis through the degradation of transcription factors such as hy5 and hyh. csn-mediated hy5 and hyh degradation also requires the activity of the putative e3 ubiquitin ligase (e3) component cop1 and the e2-conjugating enzyme variant cop10. recently, it was shown that csn also is required for auxin responses mediated by the scf-type e3 scf(tir1). ... | 2002 | 12368504 |
| different regulatory regions are required for the vernalization-induced repression of flowering locus c and for the epigenetic maintenance of repression. | vernalization, the promotion of flowering by a prolonged period of low temperature, results in repression of the floral repressor flowering locus c (flc) and in early flowering. this repression bears the hallmark of an epigenetic event: the low expression state is maintained over many cell division cycles, but expression is derepressed in progeny. we show that the two stages of the response of flc to vernalization, the repression of flc and the maintenance of the repression during growth at norm ... | 2002 | 12368502 |
| a tumor suppressor homolog, atpten1, is essential for pollen development in arabidopsis. | although it is well known that tyr phosphatases play a critical role in signal transduction in animal cells, little is understood of the functional significance of tyr phosphatases in higher plants. here, we describe the functional analysis of an arabidopsis gene (atpten1) that encodes a tyr phosphatase closely related to pten, a tumor suppressor in animals. the recombinant atpten1 protein, like its homologs in animals, is an active phosphatase that dephosphorylates phosphotyrosine and phosphati ... | 2002 | 12368500 |
| the transparent testa16 locus encodes the arabidopsis bsister mads domain protein and is required for proper development and pigmentation of the seed coat. | screening for seed pigmentation phenotypes in arabidopsis led to the isolation of three allelic yellow-seeded mutants, which defined the novel transparent testa16 (tt16) locus. cloning of tt16 was performed by t-dna tagging and confirmed by genetic complementation and sequencing of two mutant alleles. tt16 encodes the arabidopsis bsister (abs) mads domain protein. abs belongs to the recently identified "b-sister" (b(s)) clade, which contains genes of unknown function that are expressed mainly in ... | 2002 | 12368498 |
| severe developmental defects, hypersensitivity to dna-damaging agents, and lengthened telomeres in arabidopsis mre11 mutants. | the mre11 protein is essential for the long-term genetic stability of the cell and acts to ensure the efficient repair of dna damage. vertebrate cells lacking mre11 function are not viable. however, we report here that this is not the case in the model plant arabidopsis. we have isolated two different arabidopsis lines containing a t-dna copy integrated at a different point in the mre11 gene (atmre11). both mutant plant lines were hypersensitive to dna-damaging treatments but exhibited strikingl ... | 2002 | 12368497 |
| silencing of the tapetum-specific zinc finger gene taz1 causes premature degeneration of tapetum and pollen abortion in petunia. | taz1 (tapetum development zinc finger protein1; renamed from pethy; zpt3-2) cdna was first isolated as an anther-specific cdna from petunia. here, we report a functional characterization that includes analysis of spatial and temporal expression profiles and examination of anther phenotypes in taz1-silenced plants. taz1 showed a biphasic expression pattern. in the premeiotic phase, taz1 transcripts were found to accumulate in all cell types of the anther except the tapetum and gametophytic tissue ... | 2002 | 12368491 |