| mutations in the fie and mea genes that encode interacting polycomb proteins cause parent-of-origin effects on seed development by distinct mechanisms. | in flowering plants, two cells are fertilized in the haploid female gametophyte. egg and sperm nuclei fuse to form the embryo. a second sperm nucleus fuses with the central cell nucleus, which replicates to generate the endosperm, a tissue that supports embryo development. the fertilization-independent endosperm (fie) and medea (mea) genes encode wd and set domain polycomb proteins, respectively. in the absence of fertilization, a female gametophyte with a loss-of-function fie or mea allele init ... | 2000 | 11148284 |
| overexpression of the arabidopsis cbf3 transcriptional activator mimics multiple biochemical changes associated with cold acclimation. | we further investigated the role of the arabidopsis cbf regulatory genes in cold acclimation, the process whereby certain plants increase in freezing tolerance upon exposure to low temperature. the cbf genes, which are rapidly induced in response to low temperature, encode transcriptional activators that control the expression of genes containing the c-repeat/dehydration responsive element dna regulatory element in their promoters. constitutive expression of either cbf1 or cbf3 (also known as dr ... | 2000 | 11115899 |
| regulation and function of the arabidopsis aba-insensitive4 gene in seed and abscisic acid response signaling networks. | we have characterized developmental, environmental, and genetic regulation of abscisic acid-insensitive (abi)4 gene expression in arabidopsis. although expressed most strongly in seeds, abi4 transcripts are also present at low levels in vegetative tissue; vegetative expression is not induced by abscisic acid (aba) or stress treatments. comparison of transcript levels in mature seeds of aba-insensitive, aba-hypersensitive, aba-deficient, or heterochronic mutants indicates that abi4 expression is ... | 2000 | 11115891 |
| the rib1 mutant is resistant to indole-3-butyric acid, an endogenous auxin in arabidopsis. | the presence of indole-3-butyric acid (iba) as an endogenous auxin in arabidopsis has been recently demonstrated. however, the in vivo role of iba remains to be elucidated. we present the characterization of a semi-dominant mutant that is affected in its response to iba, but shows a wild-type response to indole-3-acetic acid (iaa), the predominant and most studied form of auxin. we have named this mutant rib1 for resistant to iba. root elongation assays show that rib1 is specifically resistant t ... | 2000 | 11115890 |
| characterization of the response of the arabidopsis response regulator gene family to cytokinin. | we examined the expression of a family of arabidopsis response regulators (arr) and found that the steady-state levels of rna for most are elevated very rapidly by cytokinin. using nuclear run-on assays we demonstrated that this increase in arr transcript levels in response to cytokinin is due, at least in part, to increased transcription. the start site of transcription for the arr5 gene was identified using primer extension analysis. a dna fragment comprised of 1.6 kb upstream of the arr5 tran ... | 2000 | 11115887 |
| regulation of etioplast pigment-protein complexes, inner membrane architecture, and protochlorophyllide a chemical heterogeneity by light-dependent nadph:protochlorophyllide oxidoreductases a and b. | the etioplast of dark-grown angiosperms is characterized by the prolamellar body (plb) inner membrane, the absence of chlorophyll, and the accumulation of divinyl and monovinyl derivatives of protochlorophyll(ide) a [pchl(ide) a]. either of two structurally related, but differentially expressed light-dependent nadph:pchlide oxidoreductases (pors), pora and porb, can assemble the plb and form dark-stable ternary complexes containing enzymatically photoactive pchlide-f655. here we have examined in ... | 2000 | 11115885 |
| chloroplast division and morphology are differentially affected by overexpression of ftsz1 and ftsz2 genes in arabidopsis. | in higher plants, two nuclear gene families, ftsz1 and ftsz2, encode homologs of the bacterial protein ftsz, a key component of the prokaryotic cell division machinery. we previously demonstrated that members of both gene families are essential for plastid division, but are functionally distinct. to further explore differences between ftsz1 and ftsz2 proteins we investigated the phenotypes of transgenic plants overexpressing atftsz1-1 or atftsz2-1, arabidopsis members of the ftsz1 and ftsz2 fami ... | 2000 | 11115884 |
| profilin plays a role in cell elongation, cell shape maintenance, and flowering in arabidopsis. | profilin (pfn) is an ubiquitous, low-m(r), actin-binding protein involved in the organization of the cytoskeleton of eukaryotes including higher plants. pfns are encoded by a multigene family in arabidopsis. we have analyzed in vivo functions of arabidopsis pfn by generating transgenic plants carrying a 35s-pfn-1 or 35s-antisense pfn-1 transgene. etiolated seedlings underexpressing pfn (pfn-u) displayed an overall dwarf phenotype with short hypocotyls whose lengths were 20% to 25% that of wild t ... | 2000 | 11115881 |
| a rab1 gtpase is required for transport between the endoplasmic reticulum and golgi apparatus and for normal golgi movement in plants. | we describe a green fluorescent protein (gfp)-based assay for investigating membrane traffic on the secretory pathway in plants. expression of atrab1b(n121i), predicted to be a dominant inhibitory mutant of the arabidopsis rab gtpase atrab1b, resulted in accumulation of a secreted gfp marker in an intracellular reticulate compartment reminiscent of the endoplasmic reticulum. this accumulation was alleviated by coexpressing wild-type atrab1b but not atrab8c. when a golgi-targeted and n-glycosylat ... | 2000 | 11090219 |
| antisense inhibition of the nr gene restores normal ripening to the tomato never-ripe mutant, consistent with the ethylene receptor-inhibition model. | the hormone ethylene regulates many aspects of plant growth and development, including fruit ripening. in transgenic tomato (lycopersicon esculentum) plants, antisense inhibition of ethylene biosynthetic genes results in inhibited or delayed ripening. the dominant tomato mutant, never-ripe (nr), is insensitive to ethylene and fruit fail to ripen. the nr phenotype results from mutation of the ethylene receptor encoded by the nr gene, such that it can no longer bind the hormone. nr has homology to ... | 2000 | 11080285 |
| alterations in cer6, a gene identical to cut1, differentially affect long-chain lipid content on the surface of pollen and stems. | very long chain lipids contribute to the hydrophobic cuticle on the surface of all land plants and are an essential component of the extracellular pollen coat in the brassicaceae. mutations in arabidopsis cer genes eliminate very long chain lipids from the cuticle surface and, in some cases, from the pollen coat. in arabidopsis, the loss of pollen coat lipids can disrupt interactions with the stigma, inhibiting pollen hydration and causing sterility. we have positionally cloned cer6 and demonstr ... | 2000 | 11041893 |
| the pea light-independent photomorphogenesis1 mutant results from partial duplication of cop1 generating an internal promoter and producing two distinct transcripts. | the pea lip1 (light-independent photomorphogenesis1) mutant shows many of the characteristics of light-grown development when grown in continuous darkness. to investigate the identity of lip1, cdnas encoding the pea homolog of cop1, a repressor of photomorphogenesis identified in arabidopsis, were isolated from wild-type and lip1 pea seedlings. lip1 seedlings contained a wild-type cop1 transcript as well as a larger cop1' transcript that contained an internal in-frame duplication of 894 bp. the ... | 2000 | 11041887 |
| the tt8 gene encodes a basic helix-loop-helix domain protein required for expression of dfr and ban genes in arabidopsis siliques. | the transparent testa8 (tt8) locus is involved in the regulation of flavonoid biosynthesis in arabidopsis. the tt8-3 allele was isolated from a t-dna-mutagenized arabidopsis collection and found to be tagged by an integrative molecule, thus permitting the cloning and sequencing of the tt8 gene. tt8 identity was confirmed by complementation of tt8-3 and sequence analysis of an additional allele. the tt8 gene encodes a protein that displays a basic helix-loop-helix at its c terminus and represents ... | 2000 | 11041882 |
| separable whorl-specific expression and negative regulation by enhancer elements within the agamous second intron. | we analyzed the 4-kb intragenic control region of the agamous (ag) gene to gain insight into the mechanisms controlling its expression during early flower development. we identified three major expression patterns conferred by 19 ag::reporter gene constructs: the normal ag pattern, a stamen-specific pattern, and a predominantly carpel pattern. to determine whether these three expression patterns were under negative control by apetala2 (ap2) or leunig (lug), we analyzed beta-glucuronidase stainin ... | 2000 | 11041877 |
| the arabidopsis male-sterile mutant, opr3, lacks the 12-oxophytodienoic acid reductase required for jasmonate synthesis. | jasmonic acid (ja) and its precursor 12-oxophytodienoic acid (opda) act as plant growth regulators and mediate responses to environmental cues. to investigate the role of these oxylipins in anther and pollen development, we characterized a t-dna-tagged, male-sterile mutant of arabidopsis, opr3. the opr3 mutant plants are sterile but can be rendered fertile by exogenous ja but not by opda. cloning of the mutant locus indicates that it encodes an isozyme of 12-oxophytodienoate reductase, designate ... | 2000 | 10973494 |
| genome-wide variation of the somatic mutation frequency in transgenic plants. | in order to analyse the frequency of point mutations in whole plants, several constructs containing single nonsense mutations in the beta-glucuronidase (uida) gene were used to generate transgenic arabidopsis thaliana plants. upon histochemical staining of transgenic plants, sectors indicative of transgene reactivation appeared. reversion frequencies were in the range of 10(-7)-10(-8) events per base pair, exceeding the previous estimates for other eukaryotes at least 100-fold. the frequency was ... | 2000 | 10970837 |
| sos3 function in plant salt tolerance requires n-myristoylation and calcium binding. | the salt tolerance gene sos3 (for salt overly sensitive3) of arabidopsis is predicted to encode a calcium binding protein with an n-myristoylation signature sequence. here, we examine the myristoylation and calcium binding properties of sos3 and their functional significance in plant tolerance to salt. treatment of young arabidopsis seedlings with the myristoylation inhibitor 2-hydroxymyristic acid caused the swelling of root tips, mimicking the phenotype of the salt-hypersensitive mutant sos3-1 ... | 2000 | 11006339 |
| loss of function of a rice brassinosteroid insensitive1 homolog prevents internode elongation and bending of the lamina joint. | brassinosteroids (brs) are plant growth-promoting natural products required for plant growth and development. physiological studies have demonstrated that exogenous br, alone or in combination with auxin, enhance bending of the lamina joint of rice. however, little is known about the function of endogenous br in rice or other grass species. we report here the phenotypical and molecular characterization of a rice dwarf mutant, d61, that is less sensitive to br compared to the wild type. we cloned ... | 2000 | 11006334 |
| overexpression of a gene encoding a cytochrome p450, cyp78a9, induces large and seedless fruit in arabidopsis. | an activation tagging screen in which the cauliflower mosaic virus 35s enhancer was inserted randomly into an arabidopsis genome homozygous for the floral homeotic mutation apetala2-1 (ap2-1) resulted in a line (28-5) with extraordinarily wide, heart-shaped ovaries. the ovary of the 28-5 ap2-1 mutant shows an oval shape because of increased numbers of enlarged cells. when the ap2-1 mutation is crossed out of the genetic background, more elongated rather than wider fruits are obtained. normally, ... | 2000 | 11006330 |
| analysis of the expression of cla1, a gene that encodes the 1-deoxyxylulose 5-phosphate synthase of the 2-c-methyl-d-erythritol-4-phosphate pathway in arabidopsis. | the discovery of the 2-c-methyl-d-erythritol-4-phosphate pathway for the biosynthesis of isoprenoids raises the important question of the nature and regulation of the enzymes involved in this pathway. cla1, a gene previously isolated from arabidopsis, encodes the first enzyme of the 2-c-methyl-d-erythritol-4-phosphate pathway, 1-deoxy-d-xylulose-5-phosphate synthase. we demonstrate this enzyme activity by complementation of the cla1-1 mutant phenotype and by direct enzymatic assays. based on mrn ... | 2000 | 10982425 |
| tom1, an arabidopsis gene required for efficient multiplication of a tobamovirus, encodes a putative transmembrane protein. | host-encoded factors play an important role in virus multiplication, acting in concert with virus-encoded factors. however, information regarding the host factors involved in this process is limited. here we report the map-based cloning of an arabidopsis thaliana gene, tom1, which is necessary for the efficient multiplication of tobamoviruses, positive-strand rna viruses infecting a wide variety of plants. the tom1 mrna is suggested to encode a 291-aa polypeptide that is predicted to be a multip ... | 2000 | 10944200 |
| altered expression of expansin modulates leaf growth and pedicel abscission in arabidopsis thaliana. | expansins are cell-wall-loosening proteins that induce stress relaxation and extension of plant cell walls. to evaluate their hypothesized role in cell growth, we genetically manipulated expansin gene expression in arabidopsis thaliana and assessed the consequent changes in growth and cell-wall properties. various combinations of promoters were used to drive antisense and sense sequences of atexp10, which is maximally expressed in the growing leaf and at the base of the pedicel. compared with co ... | 2000 | 10931949 |
| prenylation of the floral transcription factor apetala1 modulates its function. | the arabidopsis mads box transcription factor apetala1 (ap1) was identified as a substrate for farnesyltransferase and shown to be farnesylated efficiently both in vitro and in vivo. ap1 regulates the transition from inflorescence shoot to floral meristems and the development of sepals and petals. ap1 fused to green fluorescent protein (gfp) retained transcription factor activity and directed the expected terminal flower phenotype when ectopically expressed in transgenic arabidopsis. however, ap ... | 2000 | 10948247 |
| identification of a cyp84 family of cytochrome p450-dependent mono-oxygenase genes in brassica napus and perturbation of their expression for engineering sinapine reduction in the seeds. | cyp84 is a recently identified family of cytochrome p450-dependent mono-oxygenases defined by a putative ferulate-5-hydroxylase (f5h) from arabidopsis. until recently f5h has been thought to catalyze the hydroxylation of ferulate to 5-oh ferulate en route to sinapic acid. sinapine, a sinapate-derived ester in the seeds, is antinutritional and a target for elimination in canola meal. we have isolated three f5h-like genes (bnf5h1-3) from a cultivated brassica napus, whose amphidiploid progenitor i ... | 2000 | 10938378 |
| a comparative analysis of the plant cellulose synthase (cesa) gene family. | cesa genes are believed to encode the catalytic subunit of cellulose synthase. identification of nine distinct cesa cdnas from maize (zea mays) has allowed us to initiate comparative studies with homologs from arabidopsis and other plant species. mapping studies show that closely related cesa genes are not clustered but are found at different chromosomal locations in both arabidopsis and maize. furthermore, sequence comparisons among the cesa-deduced proteins show that these cluster in groups wh ... | 2000 | 10938350 |
| brassinosteroid-insensitive-1 is a ubiquitously expressed leucine-rich repeat receptor serine/threonine kinase. | brassinosteroid (br) mutants of arabidopsis have pleiotropic phenotypes and provide evidence that brs function throughout the life of the plant from seedling development to senescence. screens for br signaling mutants identified one locus, bri1, which encodes a protein with homology to leucine-rich repeat receptor serine (ser)/threonine (thr) kinases. twenty-seven alleles of this putative br receptor have been isolated to date, and we present here the identification of the molecular lesions of 1 ... | 2000 | 10938344 |
| regulation of abscisic acid signaling by the ethylene response pathway in arabidopsis. | although abscisic acid (aba) is involved in a variety of plant growth and developmental processes, few genes that actually regulate the transduction of the aba signal into a cellular response have been identified. in an attempt to determine negative regulators of aba signaling, we identified mutants, designated enhanced response to aba3 (era3), that increased the sensitivity of the seed to aba. biochemical and molecular analyses demonstrated that era3 mutants overaccumulate aba, suggesting that ... | 2000 | 10899978 |
| tissue-preferential expression of a rice alpha-tubulin gene, ostuba1, mediated by the first intron. | the genomic clone encoding an alpha-tubulin, ostuba1, has been isolated from rice (oryza sativa l.). the gene consists of four exons and three introns. rna-blot analysis showed that the gene is strongly expressed in actively dividing tissues, including root tips, young leaves, and young flowers. analysis of chimeric fusions between ostuba1 and beta-glucuronidase (gus) revealed that the intron 1 was required for high-level gus expression in actively dividing tissues, corresponding with normal exp ... | 2000 | 10889249 |
| regulation of ethylene biosynthesis in response to pollination in tomato flowers. | pollination of many flowers leads to an increase in ethylene synthesis and flower senescence. we have investigated the regulation of pollination-induced ethylene synthesis in tomato (lycopersicon esculentum) using flowers of the dialytic (dl) mutant, in which pollination can be manipulated experimentally, with the aim of developing a model system to study tomato flower senescence. ethylene synthesis increased rapidly in dl pistils following pollination, leading to accelerated petal senescence, a ... | 2000 | 10889245 |
| analysis of gene promoters for two tomato polygalacturonases expressed in abscission zones and the stigma. | the tomato (lycopersicon esculentum cv ailsa craig) polygalacturonase genes tapg1 (lyces;pga1;2) and tapg4 (lyces;pga1;5) are abundantly expressed in both abscission zones and the pistils of mature flowers. to further investigate the spatial and temporal expression patterns for these genes, the tapg gene promoters were ligated to beta-glucuronidase (gus) reporter genes and transformed into tomato. gus expression with both constructs was similar and entirely consistent with the expression pattern ... | 2000 | 10889236 |
| pectin engineering: modification of potato pectin by in vivo expression of an endo-1,4-beta-d-galactanase. | potato tuber pectin is rich in galactan (oligomer of beta-1,4-linked galactosyl residues). we have expressed a fungal endo-galactanase cdna in potato under control of the granule bound starch synthase promoter to obtain expression of the enzyme in tubers during growth. the transgenic plants displayed no altered phenotype compared with the wild type. fungal endo-galactanase activity was quantified in the transgenic tubers, and its expression was verified by western blot analysis. the effect of th ... | 2000 | 10852969 |
| enhanced metabolism of halogenated hydrocarbons in transgenic plants containing mammalian cytochrome p450 2e1. | chlorinated solvents, especially trichloroethylene (tce), are the most widespread groundwater contaminants in the united states. existing methods of pumping and treating are expensive and laborious. phytoremediation, the use of plants for remediation of soil and groundwater pollution, is less expensive and has low maintenance; however, it requires large land areas and there are a limited number of suitable plants that are known to combine adaptation to a particular environment with efficient met ... | 2000 | 10841534 |
| a shaker-like k(+) channel with weak rectification is expressed in both source and sink phloem tissues of arabidopsis. | rna gel blot and reverse transcription-polymerase chain reaction experiments were used to identify a single k(+) channel gene in arabidopsis as expressed throughout the plant. use of the beta-glucuronidase reporter gene revealed expression of this gene, akt2/akt3, in both source and sink phloem tissues. the akt2/akt3 gene corresponds to two previously identified cdnas, akt2 (reconstructed at its 5' end) and akt3, the open reading frame of the latter being shorter at its 5' end than that of the f ... | 2000 | 10852932 |
| characterization of auxin conjugates in arabidopsis. low steady-state levels of indole-3-acetyl-aspartate, indole-3-acetyl-glutamate, and indole-3-acetyl-glucose. | amide-linked indole-3-acetic acid (iaa) conjugates constitute approximately 90% of the iaa pool in the dicot arabidopsis, whereas ester-linked conjugates and free iaa account for approximately 10% and 1%, respectively when whole seedlings are measured. we show here that iaa-aspartate asp, iaa-glutamate (glu), and iaa-glucose (glc) are present at low levels in arabidopsis. nine-day-old wild-type arabidopsis seedlings yielded 17.4 +/- 4.6 ng g(-1) fresh weight iaa-asp and 3.5 +/- 1.6 ng g(-1) fres ... | 2000 | 10859188 |
| pat1, a new member of the gras family, is involved in phytochrome a signal transduction. | light signaling via the phytochrome a (phya) photoreceptor controls basic plant developmental processes including de-etiolation and hypocotyl elongation. we have identified a new arabidopsis mutant, pat (phytochrome a signal transduction)1-1, which shows strongly reduced responses in continuous far-red light. physiological and molecular data indicate that this mutant is disrupted at an early step of phya signal transduction. the pat1 gene encodes a cytoplasmic protein of 490 amino acids with seq ... | 2000 | 10817761 |
| protein recycling from the golgi apparatus to the endoplasmic reticulum in plants and its minor contribution to calreticulin retention. | using pulse-chase experiments combined with immunoprecipitation and n-glycan structural analysis, we showed that the retrieval mechanism of proteins from post-endoplasmic reticulum (post-er) compartments is active in plant cells at levels similar to those described previously for animal cells. for instance, recycling from the golgi apparatus back to the er is sufficient to block the secretion of as much as 90% of an extracellular protein such as the cell wall invertase fused with an hdel c-termi ... | 2000 | 10810147 |
| the arabidopsis abscisic acid response gene abi5 encodes a basic leucine zipper transcription factor. | the arabidopsis abscisic acid (aba)-insensitive abi5 mutants have pleiotropic defects in aba response, including decreased sensitivity to aba inhibition of germination and altered expression of some aba-regulated genes. we isolated the abi5 gene by using a positional cloning approach and found that it encodes a member of the basic leucine zipper transcription factor family. the previously characterized abi5-1 allele encodes a protein that lacks the dna binding and dimerization domains required f ... | 2000 | 10760247 |
| heat shock protein 101 plays a crucial role in thermotolerance in arabidopsis. | plants are sessile organisms, and their ability to adapt to stress is crucial for survival in natural environments. many observations suggest a relationship between stress tolerance and heat shock proteins (hsps) in plants, but the roles of individual hsps are poorly characterized. we report that transgenic arabidopsis plants expressing less than usual amounts of hsp101, a result of either antisense inhibition or cosuppression, grew at normal rates but had a severely diminished capacity to acqui ... | 2000 | 10760238 |
| microtubule stabilization leads to growth reorientation in arabidopsis trichomes. | the single-cell trichomes in wild-type arabidopsis are either unbranched or have two to five branches. using transgenic arabidopsis plants expressing a green fluorescent protein-microtubule-associated protein4 fusion protein, which decorates the microtubular cytoskeleton, we observed that during trichome branching, microtubules reorient with respect to the longitudinal growth axis. considering branching to be a localized microtubule-dependent growth reorientation event, we investigated the effec ... | 2000 | 10760237 |
| iron-superoxide dismutase expression in transgenic alfalfa increases winter survival without a detectable increase in photosynthetic oxidative stress tolerance. | to determine whether overexpression of fe-superoxide (sod) dismutase would increase superoxide-scavenging capacity and thereby improve the winter survival of transgenic alfalfa (medicago sativa l.) plants, two genotypes were transformed with the vector pexsod10, which contains a cdna for arabidopsis fe-sod with a chloroplast transit peptide and cauliflower mosaic virus 35s promoter. a novel fe-sod was detected by native page in both greenhouse- and field-grown transgenic plants, but activity var ... | 2000 | 10759538 |
| abscisic acid inhibition of radicle emergence but not seedling growth is suppressed by sugars. | low concentrations of sugars altered the sensitivity of seed germination to inhibition by exogenous abscisic acid (aba). germination of wild-type and aba-insensitive (abi) arabidopsis seeds was assayed on media containing aba and a variety of sugars and sugar alcohols. the inhibitory effects of aba were strongly repressed in the presence of 15 to 90 mm glucose (glc), sucrose, or fructose, but not by comparable concentrations of sorbitol or mannitol. several features of the response to glc are in ... | 2000 | 10759513 |
| a tomato peroxidase involved in the synthesis of lignin and suberin. | the last step in the synthesis of lignin and suberin has been proposed to be catalyzed by peroxidases, although other proteins may also be involved. to determine which peroxidases are involved in the synthesis of lignin and suberin, five peroxidases from tomato (lycopersicon esculentum) roots, representing the majority of the peroxidase activity in this organ, have been partially purified and characterized kinetically. the purified peroxidases with isoelectric point (pi) values of 3.6 and 9.6 sh ... | 2000 | 10759507 |
| the expression of small heat shock proteins in seeds responds to discrete developmental signals and suggests a general protective role in desiccation tolerance. | to learn more about the function and regulation of small heat shock proteins (shsps) during seed development, we studied shsp expression in wild-type and seed maturation mutants of arabidopsis by western analysis and using an hsp17.4 promoter-driven beta-glucuronidase (gus) reporter gene in transgenic plants. in the absence of stress, gus activity increases during development until the entire embryo is stained before desiccation. heat-stressed embryos stained for gus at all stages, including ear ... | 2000 | 10759505 |
| five geranylgeranyl diphosphate synthases expressed in different organs are localized into three subcellular compartments in arabidopsis. | geranylgeranyl diphosphate (ggpp) is the precursor for the biosynthesis of gibberellins, carotenoids, chlorophylls, isoprenoid quinones, and geranylgeranylated proteins in plants. there is a small gene family for ggpp synthases encoding five isozymes and one related protein in arabidopsis, and all homologs have a putative localization signal to translocate into specific subcellular compartments. using a synthetic green fluorescent protein (sgfp), we studied the subcellular localization of these ... | 2000 | 10759500 |
| the s locus glycoprotein and the s receptor kinase are sufficient for self-pollen rejection in brassica. | self-incompatibility (si) is one of several mechanisms that have evolved to prevent inbreeding in plants. si in brassica is controlled by the polymorphic s locus complex. two s locus-encoded proteins are coordinately expressed in the stigma epidermis: the cell wall-localized s locus glycoprotein (slg) and the plasma membrane-anchored s receptor kinase (srk). these proteins are thought to recognize a pollen factor that leads to the rejection of self-pollen. evidence has accumulated that indicates ... | 2000 | 10725364 |
| hormone autotrophic growth and differentiation identifies mutant lines of arabidopsis with altered cytokinin and auxin content or signaling. | we describe mutant tissue lines of arabidopsis that are able to grow in vitro as callus on hormone-free medium. the 14 lines presented here show different hormone autotrophic differentiation behaviors that can be classified into three categories: (a) forming roots (rooty callus), (b) forming shoots or shoot-like structures (shooty callus), or (c) growing without organ formation (callus). three fast-growing lines showed altered steady-state mrna levels of the cdc2 and cycd3 cell cycle genes. thre ... | 2000 | 10712535 |
| purification of a jojoba embryo wax synthase, cloning of its cdna, and production of high levels of wax in seeds of transgenic arabidopsis. | wax synthase (ws, fatty acyl-coenzyme a [coa]: fatty alcohol acyltransferase) catalyzes the final step in the synthesis of linear esters (waxes) that accumulate in seeds of jojoba (simmondsia chinensis). we have characterized and partially purified this enzyme from developing jojoba embryos. a protein whose presence correlated with ws activity during chromatographic fractionation was identified and a cdna encoding that protein was cloned. seed-specific expression of the cdna in transgenic arabid ... | 2000 | 10712527 |
| rpt2. a signal transducer of the phototropic response in arabidopsis. | the blue light receptor nph1 (for nonphototropic hypocotyl) has been considered to be the only uv-a/blue light receptor that induces a phototropic response by the hypocotyl and root of arabidopsis. by analysis of root phototropism (rpt) mutants, we show, however, the involvement of another blue light receptor as well as the existence of two separate signaling pathways working downstream of these receptors in the phototropic response. a newly isolated gene, rpt2, controls one of these pathways. t ... | 2000 | 10662859 |
| the embryo mads domain factor agl15 acts postembryonically. inhibition of perianth senescence and abscission via constitutive expression. | agl15 (agamous-like 15), a member of the mads domain family of regulatory factors, accumulates preferentially throughout the early stages of the plant life cycle. in this study, we investigated the expression pattern and possible roles of postembryonic accumulation of agl15. using a combination of reporter genes, rna gel blot analysis, and immunochemistry, we found that the agl15 protein accumulates transiently in the shoot apex in young arabidopsis and brassica seedlings and that promoter activ ... | 2000 | 10662856 |
| a specific beta-glucosidase-aggregating factor is responsible for the beta-glucosidase null phenotype in maize. | maize (zea mays l.) beta-glucosidase was extracted from shoots of a wild-type (k55) and a "null" (h95) maize genotype. enzyme activity assays and electrophoretic data showed that extracts from the null genotype had about 10% of the activity present in the normal genotype. zymograms of the null genotype were devoid of any activity bands in the resolving gel, but had a smeared zone of activity in the stacking gel after native polyacrylamide gel electrophoresis. when extracts were made with buffers ... | 2000 | 10677449 |
| intron-mediated enhancement of gene expression independent of unique intron sequences and splicing. | either of the first two introns of the arabidopsis tryptophan pathway gene pat1 elevates mrna accumulation from a pat1:beta-glucuronidase (gus) fusion roughly 5-fold without affecting the rate of pat1:gus transcription. to further explore the mechanism of this intron-mediated enhancement of gene expression, we wanted to determine whether splicing or specific intron sequences were necessary. in-frame derivatives of pat1 intron 1, whose splicing was prevented by a point mutation or large deletions ... | 2000 | 10677446 |
| haesa, an arabidopsis leucine-rich repeat receptor kinase, controls floral organ abscission. | abcission, the natural shedding of leaves, flowers and fruits, is a fundamental component of plant development. abscission is a highly regulated process that occurs at distinct zones of cells that undergo enlargement and subsequent separation. although some components of abscission, including accumulation of the hormone ethylene and cell wall-degrading enzymes, have been described, the regulatory pathways remain largely unknown. in this paper we describe a critical component required for floral ... | 2000 | 10640280 |
| identification of bfn1, a bifunctional nuclease induced during leaf and stem senescence in arabidopsis. | nuclease i enzymes are responsible for the degradation of rna and single-stranded dna during several plant growth and developmental processes, including senescence. however, in the case of senescence the corresponding genes have not been reported. we describe the identification and characterization of bfn1 of arabidopsis, and demonstrate that it is a senescence-associated nuclease i gene. bfn1 nuclease shows high similarity to the sequence of a barley nuclease induced during germination and a zi ... | 2000 | 10631260 |
| multiple mode regulation of a cysteine proteinase gene expression in rice. | in many plants, cysteine proteinases play essential roles in a variety of developmental and physiological processes. in rice (oryza sativa), rep-1 is a primary cysteine proteinase responsible for the digestion of seed storage proteins to provide nutrients to support the growth of young seedlings. in the present study, the gene encoding rep-1 was isolated, characterized, and designated as osep3a. an osep3a-specific dna probe was used to study the effect of various factors on the expression of ose ... | 2000 | 10631249 |
| antisense hema1 rna expression inhibits heme and chlorophyll biosynthesis in arabidopsis. | 5-aminolevulinic acid (ala) is a precursor in the biosynthesis of tetrapyrroles including chlorophylls and heme. the formation of ala involves two enzymatic steps which take place in the chloroplast in plants. the first enzyme, glutamyl-trna reductase, and the second enzyme, glutamate-1-semialdehyde-2,1-aminomutase, are encoded by the nuclear hema and gsa genes, respectively. to assess the significance of the hema gene for chlorophyll and heme synthesis, transgenic arabidopsis plants that expres ... | 2000 | 10631248 |
| a role for lkp2 in the circadian clock of arabidopsis. | a third member of the ztl gene family was identified in the arabidopsis genome and was named lkp2 (for lov kelch protein2). a cdna was isolated corresponding to this gene, and plants overexpressing lkp2 were generated. the overexpression of lkp2 resulted in arrhythmic phenotypes for a number of circadian clock outputs in both constant light and constant darkness, long hypocotyls under multiple fluences of both red and blue light, and a loss of photoperiodic control of flowering time. the lkp2 mr ... | 2001 | 11752379 |
| antisense expression of an arabidopsis ran binding protein renders transgenic roots hypersensitive to auxin and alters auxin-induced root growth and development by arresting mitotic progress. | we cloned a cdna encoding an arabidopsis ran binding protein, atranbp1c, and generated transgenic arabidopsis expressing the antisense strand of the atranbp1c gene to understand the in vivo functions of the ran/ranbp signal pathway. the transgenic plants showed enhanced primary root growth but suppressed growth of lateral roots. auxin significantly increased lateral root initiation and inhibited primary root growth in the transformants at 10 pm, several orders of magnitude lower than required to ... | 2001 | 11752376 |
| overexpression of arabidopsis esr1 induces initiation of shoot regeneration. | functional screening of an arabidopsis cdna library enabled the identification of a novel cdna, esr1 (for enhancer of shoot regeneration), that can confer cytokinin-independent shoot formation when overexpressed in arabidopsis root explants. neither callus induction nor root formation was affected by esr1 overexpression. esr1 encodes a putative transcription factor with an ap2/erebp domain. surprisingly, esr1 overexpression also greatly increased the efficiency of shoot regeneration from root ex ... | 2001 | 11752375 |
| conditional circadian regulation of phytochrome a gene expression. | the phytochrome photoreceptors and the circadian clock control many of the same developmental processes, in all organs and throughout the growth of arabidopsis plants. phytochrome a (phya) provides light input signals to entrain the circadian clock. the clock is known to rhythmically regulate its light input pathway, so we tested rhythmic regulation of phya, using transgenic plants carrying a phya promoter fusion to the luciferase reporter (phya:luc). we provide the first images of luc activity ... | 2001 | 11743124 |
| dex1, a novel plant protein, is required for exine pattern formation during pollen development in arabidopsis. | to identify factors that are required for proper pollen wall formation, we have characterized the t-dna-tagged, dex1 mutation of arabidopsis, which results in defective pollen wall pattern formation. this study reports the isolation and molecular characterization of dex1 and morphological and ultrastructural analyses of dex1 plants. dex1 encodes a novel plant protein that is predicted to be membrane associated and contains several potential calcium-binding domains. pollen wall development in dex ... | 2001 | 11743117 |
| colocalization of plastid division proteins in the chloroplast stromal compartment establishes a new functional relationship between ftsz1 and ftsz2 in higher plants. | chloroplast division is driven by a macromolecular complex containing components that are positioned on the cytosolic surface of the outer envelope, the stromal surface of the inner envelope, and in the intermembrane space. the only constituents of the division apparatus identified thus far are the tubulin-like proteins ftsz1 and ftsz2, which colocalize to rings at the plastid division site. however, the precise positioning of these rings relative to the envelope membranes and to each other has ... | 2001 | 11743110 |
| a condensing enzyme from the seeds of lesquerella fendleri that specifically elongates hydroxy fatty acids. | lesquerella fendleri seed oil contains up to 60% hydroxy fatty acids, nearly all of which is the 20-carbon hydroxy fatty acid lesquerolic acid (d-14-hydroxyeicos-cis-11-enoic acid). previous work suggested that lesquerolic acid in l. fendleri was formed by the elongation of the 18-carbon hydroxy fatty acid, ricinoleic acid. to identify a gene encoding the enzyme involved in hydroxy fatty acid elongation, an l. fendleri genomic dna library was screened using the coding region of the arabidopsis f ... | 2001 | 11743108 |
| a slow maturation of a cysteine protease with a granulin domain in the vacuoles of senescing arabidopsis leaves. | arabidopsis rd21 is a cysteine protease of the papain family. unlike other members of the papain family, rd21 has a c-terminal extension sequence composed of two domains, a 2-kd proline-rich domain and a 10-kd domain homologous to animal epithelin/granulin family proteins. the rd21 protein was accumulated as 38- and 33-kd proteins in arabidopsis leaves. an immunoblot showed that the 38-kd protein had the granulin domain, whereas the 33-kd protein did not. a pulse-chase experiment with bright-yel ... | 2001 | 11743107 |
| circadian clock-regulated expression of phytochrome and cryptochrome genes in arabidopsis. | many physiological and biochemical processes in plants exhibit endogenous rhythms with a period of about 24 h. endogenous oscillators called circadian clocks regulate these rhythms. the circadian clocks are synchronized to the periodic environmental changes (e.g. day/night cycles) by specific stimuli; among these, the most important is the light. photoreceptors, phytochromes, and cryptochromes are involved in setting the clock by transducing the light signal to the central oscillator. in this wo ... | 2001 | 11743105 |
| interactions between syntaxins identify at least five snare complexes within the golgi/prevacuolar system of the arabidopsis cell. | the syntaxin family of soluble n-ethyl maleimide sensitive factor adaptor protein receptors (snares) is known to play an important role in the fusion of transport vesicles with specific organelles. twenty-four syntaxins are encoded in the genome of the model plant arabidopsis thaliana. these 24 genes are found in 10 gene families and have been reclassified as syntaxins of plants (syps). some of these gene families have been previously characterized, with the syp2-type syntaxins being found in th ... | 2001 | 11739776 |
| embryonic flower2, a novel polycomb group protein homolog, mediates shoot development and flowering in arabidopsis. | in higher plants, developmental phase changes are regulated by a complex gene network. loss-of-function mutations in the embryonic flower genes (emf1 and emf2) cause arabidopsis to flower directly, bypassing vegetative shoot growth. this phenotype suggests that the emf genes play a major role in repression of the reproductive program. positional cloning of emf2 revealed that it encodes a zinc finger protein similar to fertilization-independent seed2 and vernalization2 of arabidopsis. these genes ... | 2001 | 11701882 |
| enhanced levels of the aroma and flavor compound s-linalool by metabolic engineering of the terpenoid pathway in tomato fruits. | the aromas of fruits, vegetables, and flowers are mixtures of volatile metabolites, often present in parts per billion levels or less. we show here that tomato (lycopersicon esculentum mill.) plants transgenic for a heterologous clarkia breweri s-linalool synthase (lis) gene, under the control of the tomato late-ripening-specific e8 promoter, synthesize and accumulate s-linalool and 8-hydroxylinalool in ripening fruits. apart from the difference in volatiles, no other phenotypic alterations were ... | 2001 | 11706204 |
| the arabidopsis protein shi represses gibberellin responses in arabidopsis and barley. | the current model of gibberellin (ga) signal transduction is based on a derepressible system and a number of candidate negative regulators have been identified in arabidopsis. we previously have reported the identification of the arabidopsis gene short internodes (shi) that causes suppression of ga responses when constitutively activated. in this paper, we show by using reporter gene analysis that the shi gene is expressed in young organs, e.g. shoot apices and root tips. the model predicts a su ... | 2001 | 11706176 |
| components of the arabidopsis c-repeat/dehydration-responsive element binding factor cold-response pathway are conserved in brassica napus and other plant species. | many plants increase in freezing tolerance in response to low, nonfreezing temperatures, a phenomenon known as cold acclimation. cold acclimation in arabidopsis involves rapid cold-induced expression of the c-repeat/dehydration-responsive element binding factor (cbf) transcriptional activators followed by expression of cbf-targeted genes that increase freezing tolerance. here, we present evidence for a cbf cold-response pathway in brassica napus. we show that b. napus encodes cbf-like genes and ... | 2001 | 11706173 |
| the arabidopsis somatic embryogenesis receptor kinase 1 gene is expressed in developing ovules and embryos and enhances embryogenic competence in culture. | we report here the isolation of the arabidopsis somatic embryogenesis receptor-like kinase 1 (atserk1) gene and we demonstrate its role during establishment of somatic embryogenesis in culture. the atserk1 gene is highly expressed during embryogenic cell formation in culture and during early embryogenesis. the atserk1 gene is first expressed in planta during megasporogenesis in the nucellus [corrected] of developing ovules, in the functional megaspore, and in all cells of the embryo sac up to fe ... | 2001 | 11706164 |
| antisense inhibition of threonine synthase leads to high methionine content in transgenic potato plants. | methionine (met) and threonine (thr) are members of the aspartate family of amino acids. in plants, their biosynthetic pathways diverge at the level of o-phosphohomo-serine (ser). the enzymes cystathionine gamma-synthase and thr synthase (ts) compete for the common substrate o-phosphohomo-ser with the notable feature that plant ts is activated through s-adenosyl-met, a metabolite derived from met. to investigate the regulation of this branch point, we engineered ts antisense potato (solanum tube ... | 2001 | 11706163 |
| transgenically expressed t-rep of tomato yellow leaf curl sardinia virus acts as a trans-dominant-negative mutant, inhibiting viral transcription and replication. | we have previously shown that transgenic expression of a truncated c1 gene of tomato yellow leaf curl sardinia virus (tylcsv), expressing the first 210 amino acids of the replication-associated protein (t-rep) and potentially coexpressing the c4 protein, confers resistance to the homologous virus in nicotiana benthamiana plants. in the present study we have investigated the role of t-rep and c4 proteins in the resistance mechanism, analyzing changes in virus transcription and replication. transg ... | 2001 | 11602699 |
| engineering salt-tolerant brassica plants: characterization of yield and seed oil quality in transgenic plants with increased vacuolar sodium accumulation. | transgenic brassica napus plants overexpressing atnhx1, a vacuolar na(+)/h(+) antiport from arabidopsis thaliana, were able to grow, flower, and produce seeds in the presence of 200 mm sodium chloride. although the transgenic plants grown in high salinity accumulated sodium up to 6% of their dry weight, growth of the these plants was only marginally affected by the high salt concentration. moreover, seed yields and the seed oil quality were not affected by the high salinity of the soil. our resu ... | 2001 | 11606781 |
| flu: a negative regulator of chlorophyll biosynthesis in arabidopsis thaliana. | tetrapyrroles such as chlorophylls and bacteriochlorophylls play a fundamental role in the energy absorption and transduction activities of photosynthetic organisms. because of these molecules, however, photosynthetic organisms are also prone to photooxidative damage. they had to evolve highly efficient strategies to control tetrapyrrole biosynthesis and to prevent the accumulation of free intermediates that potentially are extremely destructive when illuminated. in higher plants, the metabolic ... | 2001 | 11606728 |
| effects of p(sag12)-ipt gene expression on development and senescence in transgenic lettuce. | an ipt gene under control of the senescence-specific sag12 promoter from arabidopsis (p(sag12)-ipt) significantly delayed developmental and postharvest leaf senescence in mature heads of transgenic lettuce (lactuca sativa l. cv evola) homozygous for the transgene. apart from retardation of leaf senescence, mature, 60-d-old plants exhibited normal morphology with no significant differences in head diameter or fresh weight of leaves and roots. induction of senescence by nitrogen starvation rapidly ... | 2001 | 11598225 |
| dominant negative guard cell k+ channel mutants reduce inward-rectifying k+ currents and light-induced stomatal opening in arabidopsis. | inward-rectifying potassium (k+(in)) channels in guard cells have been suggested to provide a pathway for k+ uptake into guard cells during stomatal opening. to test the proposed role of guard cell k+(in) channels in light-induced stomatal opening, transgenic arabidopsis plants were generated that expressed dominant negative point mutations in the k+(in) channel subunit kat1. patch-clamp analyses with transgenic guard cells from independent lines showed that k+(in) current magnitudes were reduce ... | 2001 | 11598222 |
| cytoplasmic dynein light intermediate chain is required for discrete aspects of mitosis in caenorhabditis elegans. | we describe phenotypic characterization of dli-1, the caenorhabditis elegans homolog of cytoplasmic dynein light intermediate chain (lic), a subunit of the cytoplasmic dynein motor complex. animals homozygous for loss-of-function mutations in dli-1 exhibit stochastic failed divisions in late larval cell lineages, resulting in zygotic sterility. dli-1 is required for dynein function during mitosis. depletion of the dli-1 gene product through rna-mediated gene interference (rnai) reveals an early ... | 2001 | 11598181 |
| the arabidopsis tt2 gene encodes an r2r3 myb domain protein that acts as a key determinant for proanthocyanidin accumulation in developing seed. | in arabidopsis, proanthocyanidins specifically accumulate in the endothelium during early seed development. at least three transparent testa (tt) genes, tt2, tt8, and ttg1, are necessary for the normal expression of several flavonoid structural genes in immature seed, such as dihydroflavonol-4-reductase and banyuls (ban). tt8 and ttg1 were characterized recently and found to code for a basic helix-loop-helix domain transcription factor and a wd-repeat-containing protein, respectively. here the m ... | 2001 | 11549766 |
| leaf-specific upregulation of chloroplast translocon genes by a cct motif-containing protein, cia 2. | chloroplasts are a major destination of protein traffic within leaf cells. protein import into chloroplasts is mediated by a set of translocon complexes at the chloroplast envelope. current data indicate that the expression of translocon genes is regulated in a tissue-specific manner, possibly to accommodate the higher import demand of chloroplasts in leaves and the lower demand of plastids in other tissues. we have designed a transgene-based positive screen to isolate mutants disrupted in prote ... | 2001 | 11549763 |
| the phenylalanine ammonia-lyase gene family in raspberry. structure, expression, and evolution. | in raspberry (rubus idaeus), development of fruit color and flavor are critically dependent on products of the phenylpropanoid pathway. to determine how these metabolic functions are integrated with the fruit ripening program, we are examining the properties and expression of key genes in the pathway. here, we report that l- phenylalanine ammonia-lyase (pal) is encoded in raspberry by a family of two genes (ripal1 and ripal2). ripal1 shares 88% amino acid sequence similarity to ripal2, but phylo ... | 2001 | 11553751 |
| overexpression of acyl carrier protein-1 alters fatty acid composition of leaf tissue in arabidopsis. | acyl carrier protein (acp) is a small (9 kd) acidic protein that is an essential cofactor in plant fatty acid biosynthesis. most plants have several isoforms of acp, some of which are expressed constitutively and others that appear to be more tissue specific. although the critical role of acp in fatty acid biosynthesis has been established, the role of the diverse number of isoforms has yet to be elucidated. we have generated transgenic arabidopsis plants that express high levels of acp-1, a see ... | 2001 | 11553750 |
| the properties of the chlorophyll a/b-binding proteins lhca2 and lhca3 studied in vivo using antisense inhibition. | the specific functions of the light-harvesting proteins lhca2 and lhca3 were studied in arabidopsis ecotype colombia antisense plants in which the proteins were individually repressed. the antisense effect was specific in each plant, but levels of lhca proteins other than the targeted products were also affected. the contents of lhca1 and lhca4 were unaffected, but lhca3 (in lhca2-repressed plants) was almost completely depleted, and lhca2 decreased to about 30% of wild-type levels in lhca3-repr ... | 2001 | 11553743 |
| the arabidopsis immutans mutation affects plastid differentiation and the morphogenesis of white and green sectors in variegated plants. | the immutans (im) variegation mutant of arabidopsis has green and white leaf sectors due to the action of a nuclear recessive gene, immutans (im). this gene encodes the im protein, which is a chloroplast homolog of the mitochondrial alternative oxidase. because the white sectors of im accumulate the noncolored carotenoid, phytoene, im likely serves as a redox component in phytoene desaturation. in this paper, we show that im has a global impact on plant growth and development and is required for ... | 2001 | 11553735 |
| functional conservation of plant secondary metabolic enzymes revealed by complementation of arabidopsis flavonoid mutants with maize genes. | mutations in the transparent testa (tt) loci abolish pigment production in arabidopsis seed coats. the tt4, tt5, and tt3 loci encode chalcone synthase, chalcone isomerase, and dihydroflavonol 4-reductase, respectively, which are essential for anthocyanin accumulation and may form a macromolecular complex. here, we show that the products of the maize (zea mays) c2, chi1, and a1 genes complement arabidopsis tt4, tt5, and tt3 mutants, restoring the ability of these mutants to accumulate pigments in ... | 2001 | 11553733 |
| modifications of cellulose synthase confer resistance to isoxaben and thiazolidinone herbicides in arabidopsis ixr1 mutants. | in many higher plants, cellulose synthesis is inhibited by isoxaben and thiazolidinone herbicides such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl) phenyl-4-thiazolidinone. semidominant mutations at the ixr1 and ixr2 loci of arabidopsis confer isoxaben and thiazolidinone resistance. isolation of the ixr1 gene by map-based cloning revealed that it encodes the atcesa3 isoform of cellulose synthase. the two known mutant alleles contain point mutations that replace glycine 998 with aspartic aci ... | 2001 | 11517344 |
| knat2: evidence for a link between knotted-like genes and carpel development. | the knat2 (for knotted-like from arabidopsis thaliana 2) homeobox gene is expressed in the vegetative apical meristem. it is also active during flower development, suggesting a function in the structuring of flowers. to investigate its role, we used a dexamethasone (dex)-inducible system to generate transgenic plants that overexpressed a fusion of knat2 with the hormone binding domain of the glucocorticoid receptor. dex-induced plants were similar to plants overexpressing the closely related kna ... | 2001 | 11487688 |
| the arabidopsis dual-affinity nitrate transporter gene atnrt1.1 (chl1) is activated and functions in nascent organ development during vegetative and reproductive growth. | the atnrt1.1 (chl1) transporter provides a primary mechanism for nitrate uptake in arabidopsis and is expected to localize to the epidermis and cortex of the mature root, where the bulk of nitrate uptake occurs. using fusions to gfp/gus marker genes, we found chl1 expression concentrated in the tips of primary and lateral roots, with very low signals in the epidermis and cortex. a time-course study showed that chl1 is activated in the primary root tip early in seedling development and at the ear ... | 2001 | 11487691 |
| emf1, a novel protein involved in the control of shoot architecture and flowering in arabidopsis. | shoot architecture and flowering time in angiosperms depend on the balanced expression of a large number of flowering time and flower meristem identity genes. loss-of-function mutations in the arabidopsis embryonic flower (emf) genes cause arabidopsis to eliminate rosette shoot growth and transform the apical meristem from indeterminate to determinate growth by producing a single terminal flower on all nodes. we have identified the emf1 gene by positional cloning. the deduced polypeptide has no ... | 2001 | 11487698 |
| developmental abnormalities and reduced fruit softening in tomato plants expressing an antisense rab11 gtpase gene. | a cdna clone from tomato fruit encodes a protein with strong homology with the rab11/ypt3 class of small gtpases that is thought to be involved in the control of protein trafficking within cells. the gene, lerab11a, showed a pattern consistent with a single copy in dna gel blots. the corresponding mrna was developmentally regulated during fruit ripening, and its expression was inhibited in several ripening mutants. its reduced expression in the never-ripe mutant indicates that it may be induced ... | 2001 | 11487695 |
| somatic and germinal excision activities of the arabidopsis transposon tag1 are controlled by distinct regulatory sequences within tag1. | various sequences within tag1, the endogenous transposon of arabidopsis, were examined to determine how tag1 excision and expression are regulated. the 5' intron for the major 2.3-kb tag1 transcript was found to be critical for the accumulation of tag1 transcripts and for high rates of somatic excision. this was true for the autonomous element in cauliflower mosaic virus 35s-tag1-beta-glucuronidase constructs and for a two-component system using the 35s promoter to produce tag1 transposase and a ... | 2001 | 11487697 |
| t-dna-associated duplication/translocations in arabidopsis. implications for mutant analysis and functional genomics. | t-dna insertion mutants have become a valuable resource for studies of gene function in arabidopsis. in the course of both forward and reverse genetic projects, we have identified novel interchromosomal rearrangements in two arabidopsis t-dna insertion lines. both rearrangements were unilateral translocations associated with the left borders of t-dna inserts that exhibited normal mendelian segregation. in one study, we characterized the embryo-defective88 mutation. although emb88 had been mapped ... | 2001 | 11500551 |
| overexpression of knat1 in lettuce shifts leaf determinate growth to a shoot-like indeterminate growth associated with an accumulation of isopentenyl-type cytokinins. | leaves are specialized organs characterized by defined developmental destiny and determinate growth. the overexpression of knotted1-like homeobox genes in different species has been shown to alter leaf shape and development, but a definite role for this class of genes remains to be established. transgenics that overexpress knotted1-like genes present some traits that are characteristic of altered cytokinin physiology. here we show that lettuce (lactuca sativa) leaves that overexpress knat1, an a ... | 2001 | 11500537 |
| old yellow enzyme: reduction of nitrate esters, glycerin trinitrate, and propylene 1,2-dinitrate. | the reaction of the old yellow enzyme and reduced flavins with organic nitrate esters has been studied. reduced flavins have been found to react readily with glycerin trinitrate (gtn ) (nitroglycerin) and propylene dinitrate, with rate constants at ph 7.0, 25 degrees c of 145 m(-1)s(-1) and 5.8 m(-1)s(-1), respectively. with gtn, the secondary nitrate was removed reductively 6 times faster than the primary nitrate, with liberation of nitrite. with propylene dinitrate, on the other hand, the prim ... | 2001 | 11438708 |
| functional analysis of cyclin-dependent kinase inhibitors of arabidopsis. | cyclin-dependent kinase inhibitors, such as the mammalian p27(kip1) protein, regulate correct cell cycle progression and the integration of developmental signals with the core cell cycle machinery. these inhibitors have been described in plants, but their function remains unresolved. we have isolated seven genes from arabidopsis that encode proteins with distant sequence homology with p27(kip1), designated kip-related proteins (krps). the krps were characterized by their domain organization and ... | 2001 | 11449057 |
| repressing a repressor: gibberellin-induced rapid reduction of the rga protein in arabidopsis. | rga (for repressor of ga1-3) and spindly (spy) are likely repressors of gibberellin (ga) signaling in arabidopsis because the recessive rga and spy mutations partially suppressed the phenotype of the ga-deficient mutant ga1-3. we found that neither rga nor spy altered the ga levels in the wild-type or the ga1-3 background. however, expression of the ga biosynthetic gene ga4 was reduced 26% by the rga mutation, suggesting that partial derepression of the ga response pathway by rga resulted in the ... | 2001 | 11449051 |
| one plant actin isovariant, act7, is induced by auxin and required for normal callus formation. | during plant growth and development, the phytohormone auxin induces a wide array of changes that include cell division, cell expansion, cell differentiation, and organ initiation. it has been suggested that the actin cytoskeleton plays an active role in the elaboration of these responses by directing specific changes in cell morphology and cytoarchitecture. here we demonstrate that the promoter and the protein product of one of the arabidopsis vegetative actin genes, act7, are rapidly and strong ... | 2001 | 11449050 |
| overexpression of the heterotrimeric g-protein alpha-subunit enhances phytochrome-mediated inhibition of hypocotyl elongation in arabidopsis. | plant heterotrimeric g-proteins have been implicated in a number of signaling processes. however, most of these studies are based on biochemical or pharmacological approaches. to examine the role of heterotrimeric g-proteins in plant development, we generated transgenic arabidopsis expressing the galpha subunit of the heterotrimeric g-protein under the control of a glucocorticoid-inducible promoter. with the conditional overexpression of either the wild type or a constitutively active version of ... | 2001 | 11449056 |
| nad malic enzyme and the control of carbohydrate metabolism in potato tubers. | potato (solanum tuberosum) plants were transformed with a cdna encoding the 59-kd subunit of the potato tuber nad-dependent malic enzyme (nadme) in the antisense orientation. measurements of the maximum catalytic activity of nadme in tubers revealed a range of reductions in the activity of this enzyme down to 40% of wild-type activity. there were no detrimental effects on plant growth or tuber yield. biochemical analyses of developing tubers indicated that a reduction in nadme activity had no de ... | 2001 | 11457964 |
| metabolic engineering of essential oil yield and composition in mint by altering expression of deoxyxylulose phosphate reductoisomerase and menthofuran synthase. | peppermint (mentha x piperita l.) was independently transformed with a homologous sense version of the 1-deoxy-d-xylulose-5-phosphate reductoisomerase cdna and with a homologous antisense version of the menthofuran synthase cdna, both driven by the camv 35s promoter. two groups of transgenic plants were regenerated in the reductoisomerase experiments, one of which remained normal in appearance and development; another was deficient in chlorophyll production and grew slowly. transgenic plants of ... | 2001 | 11427737 |
| control of axillary bud initiation and shoot architecture in arabidopsis through the supershoot gene. | the aerial architecture of flowering plants is determined to a large extent by shoot growth and shoot branching arising from the initiation and growth of axillary meristems. we have identified an arabidopsis mutant, supershoot (sps), which is characterized by a massive overproliferation of shoots, such that a single plant can generate 500 or more inflorescences. analysis of the mutant plants shows that the primary defect is because of an increase in the number of meristems formed in leaf axils, ... | 2001 | 11410537 |