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Results for “Gene Expression Regulation, Plant”

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At least 55 records · Page 3Linked to original sources
PubMed1998

A transcription activation system for regulated gene expression in transgenic plants.

A widely applicable promoter system is described that allows a gene of interest to be activated in specific plant tissues after a cross between defined transgenic lines. The promoter, pOp, consists of lac operators cloned upstream of a minimal promoter. No expression was detected from this promoter when placed upstream of a beta-glucuronidase (GUS) reporter gene in transgenic plants. Transcription from the promoter was activated by crossing reporter plants with activator lines that expressed a chimeric transcription factor, LhG4. This factor comprised transcription-activation domain-II from Gal4 of Saccharomyces cerevisiae fused to a mutant lac-repressor that binds its operator with increased affinity. When LhG4 was expressed from the CaMV 35S promoter, the spatial and quantitative expression characteristics of the 35S promoter were exhibited by the GUS reporter. The LhG4/pOp system may be used to study toxic or deleterious gene products, to coordinate the expression of multiple gene products, to restrict transgene phenotypes to the F1 generation, and to generate hybrid seed. The LhG4 system offers spatially regulated gene expression in the tissues of whole plants growing under normal conditions without the need for external intervention. It complements inducible expression systems that offer temporal control of gene expression in tissues that can be treated with inducing chemicals.

Bacterial Proteins↗
PubMed1997

Translational regulation of gene expression in plants.

Translational regulation plays a major role in plant gene expression. Recent advances have been made in understanding how this mechanism of control is directed in the chloroplast as well as in the cytoplasm. Our knowledge of translational regulation in plant mitochondria, however, is limited. Translational control of gene expression in yeast mitochondria suggests that similar mechanisms will also play a significant role in the expression of plant mitochondrial genes.

Journal Article↗
PubMedDate not supplied

Light regulation of plant gene expression by an upstream enhancer-like element.

Light regulates many varied physiological and developmental phenomena during plant growth and differentiation, including the formation of a photosynthetically competent chloroplast from a proplastid. The expression of ribulose 1,5-bisphosphate carboxylase small subunit (rbcS) genes is regulated by light in a development- and tissue-specific manner2,3. In some plant species, phytochrome has been demonstrated to mediate this response, and photoregulation of rbcS expression occurs at least in part at the level of transcription. We have shown previously that a 5'-noncoding fragment (4-973 base pairs (bp) upstream of the messenger RNA cap site) of the pea rbcS ss3.6 gene contains all of the nucleotide sequence information necessary to direct the photoregulated expression of a bacterial chloramphenicol acetyltransferase (cat) gene in tobacco. Consistent with these findings, Morelli et al.11 have shown by deletion analysis of a second rbcS gene promoter, that the sequences required for photoregulated expression of rbcS E9 reside within the 5'-noncoding region. They identified an upstream region of approximately 700 bp needed for maximum transcription but not light-dark regulation, and a region from -35 to -2 bp which included the TATA box and contained the necessary information for light responsiveness. We now demonstrate that regulatory sequences 5' distal to the rbcS ss3.6 TATA box and transcriptional start site not only contain the information necessary for maximum expression, but also confer photoregulation. These upstream regulatory sequences function independently of orientation when fused to their homologous promoter or a heterologous promoter.

Acetyltransferases↗
PubMed2003

Transcriptional regulation of sorghum defense determinants against a phloem-feeding aphid.

When attacked by a phloem-feeding greenbug aphid (Schizaphis graminum), sorghum (Sorghum bicolor) activates jasmonic acid (JA)- and salicylic acid (SA)-regulated genes, as well as genes outside known wounding and SA signaling pathways. A collection of 672 cDNAs was obtained by differential subtraction with cDNAs prepared from sorghum seedlings infested by greenbug aphids and those from uninfested seedlings. Subsequent expression profiling using DNA microarray and northern-blot analyses identified 82 transcript types from this collection responsive to greenbug feeding, methyl jasmonate (MeJA), or SA application. DNA sequencing analyses indicated that these encoded proteins functioning in direct defense, defense signaling, oxidative burst, secondary metabolism, abiotic stress, cell maintenance, and photosynthesis, as well as proteins of unknown function. In response to insect feeding, sorghum increased transcript abundance of numerous defense genes, with some SA-dependent pathogenesis-related genes responding to greenbug more strongly than to SA. In contrast, only weak induction of MeJA-regulated defense genes was observed after greenbug treatment. However, infestation tests confirmed that JA-regulated pathways were effective in plant defense against greenbugs. Activation of certain transcripts exclusively by greenbug infestation was observed, and may represent unique signal transduction events independent of JA- and SA-regulated pathways. Results indicate that plants coordinately regulate defense gene expression when attacked by phloem-feeding aphids, but also suggest that aphids are able to avoid triggering activation of some otherwise potentially effective plant defensive machinery, possibly through their particular mode of feeding.

Animals↗
PubMed1996

The interaction of light and abscisic acid in the regulation of plant gene expression.

Extended dark treatments of light-grown plants of both Lemna gibba and Arabidopsis thaliana resulted in substantial increases in abscisic acid (ABA) concentrations. The concentration of ABA could be negatively regulated by phytochrome action in Lemna. As has been noted in other species, ABA treatment reduced Lemna rbcS and Lhcb RNA levels, which are positively regulated by phytochrome in many species. In view of these observations, the possibility that phytochrome effects on gene expression may be mediated primarily by changes in ABA was tested using a transient assay in intact plants. The phytochrome responsiveness of the Lemna Lhcb2*1 promoter was still apparent in the presence of exogenous ABA. Additionally, when 2-bp mutations were introduced into this promoter so that phytochrome responsiveness was lost, a response to exogenous ABA was still present. We conclude that phytochrome- and ABA-response elements are separable in the Lhcb2*1 promoter. We tested whether the effects of ABA on RNA abundance could be inhibited by treatment with gibberellin and found no evidence for such an inhibition. We have also found that the ABA-responsive Em promoter of wheat can be negatively regulated by phytochrome action. It is likely that this regulation is mediated at least in part by phytochrome-induced changes in ABA levels. Our results demonstrate that it is essential to take into account that dark treatments and the phytochrome system can affect ABA levels when interpreting studies of light-regulated genes.

Abscisic Acid↗
PubMed2006

Identification of new gene expression regulators specifically expressed during plant seed maturation.

A cDNA-AFLP approach on Linum usitatissimum (flax) was used to identify genes specifically expressed during the seed maturation process. Among the 20,000 cDNA-AFLP tags produced, 486 were selected for their seed-specific expression during maturation. When compared with the publicly available databases, half of them presented some significant similarity with known plant sequences. The results obtained confirmed the accuracy of the approach as numerous genes previously described as being expressed exclusively in plant seeds were identified in this screen. The focus was on sequences similar to plant regulators involved in the control of gene expression, either at the transcriptional, post-transcriptional, or post-translational levels. Using a real-time RT-PCR approach, seed-specific expression kinetics were confirmed for 13 of these regulators that were never characterized for being expressed during seed maturation. Among these, a flax gene of the non-LEC1-like HAP3 family and a flax MYB factor were shown to be expressed in specialized tissues of flax embryo using an in situ hybridization approach. By expression kinetic comparison between these flax genes and their Arabidopsis counterparts, it was found that the new HAP3 gene should be related to a ubiquitous seed maturation mechanism, while a new MYB factor appears to be related to a more seed-specific maturation mechanism. These results demonstrate the utility of the flax database in not only identifying new genes expressed during seed maturation but also in being able to highlight the distinction between conserved and non-conserved seed maturation mechanisms.

Arabidopsis↗
PubMed1998

[Genetic transformation of plants, recombination processes, and gene expression regulation in transgenic plants].

Recent studies in molecular biology and gene engineering were conducive to accumulation of numerous facts which help better understand the processes of plant genome functioning and follow up the effects of recombination processes in purposefully modified genome of a transformed plant on its expression. This review analyzes the major approaches to studies and results attained in plant gene engineering and plant genome imprinting.

DNA Methylation↗
PubMed2003

Chemically regulated gene expression in plants.

Chemically inducible systems that activate or inactivate gene expression have many potential applications in the determination of gene function and in plant biotechnology. The precise timing and control of gene expression are important aspects of chemically inducible systems. Several systems have been developed and used to analyze gene function, marker-free plant transformation, site-specific DNA excision, activation tagging, conditional genetic complementation, and restoration of male fertility. Chemicals that are used to regulate transgene expression include the antibiotic tetracycline, the steroids dexamethasone and estradiol, copper, ethanol, the inducer of pathogen-related proteins benzothiadiazol, herbicide safeners, and the insecticide methoxyfenozide. Systems that are suitable for field application are particularly useful for experimental systems and have potential applications in biotechnology.

Copper↗
PubMed1997

Light-regulated expression of the pea plastocyanin gene is mediated by elements within the transcribed region of the gene.

Expression of the pea plastocyanin gene (PetE) is regulated by light in both pea and transgenic tobacco plants. However, the PetE promoter with the 5' untranslated leader region does not direct light-regulated expression of the GUS reporter gene in transgenic tobacco. This suggested that sequences downstream of the translation start of the PetE gene are required for light-regulated expression. To investigate this possibility the expression of a series of chimeric gene constructs in transgenic tobacco plants was examined to assess the contributions of the promoter, the 5' untranslated leader region, the coding region and the 3' region of the PetE gene to light-regulated expression. Both the coding region and the 5' untranslated leader region of the PetE gene were found to be required for full light regulation. Full light regulation of chimeric gene constructs containing the cauliflower mosaic virus (CaMV) 35S promoter required the deletion of CaMV 5' leader and polylinker sequences from the constructs. The presence of CaMV and polylinker sequences at the 5' end of the PetE leader masked the light regulation directed by the transcribed region of the pea PetE gene.

Base Sequence↗
PubMed2006

Leaf-specific suppression of deoxyhypusine synthase in Arabidopsis thaliana enhances growth without negative pleiotropic effects.

Deoxyhypusine synthase (DHS) mediates the first of two enzymatic reactions required for the post-translational activation of eukaryotic translation initiation factor 5A (eIF5A), which in turn is thought to facilitate translation of specific mRNAs. Analyses of GUS activity in transgenic Arabidopsis plants expressing the GUS reporter gene under regulation of the promoter for AtDHS revealed that the expression of DHS changes both spatially and temporally as development progresses. In particular, DHS is expressed not only in rosette leaves, but also in the anthers of developing flowers. To determine the role of DHS in leaves, transgenic plants in which DHS was selectively suppressed in rosettes of Arabidopsis plants were prepared. This was achieved by expressing AtDHS 3'-UTR cDNA as a transgene under regulation of the promoter for AtRbcS2, a gene encoding the small subunit of Rubisco. The dominant phenotypic traits of the DHS-suppressed plants proved to be a dramatic enhancement of both vegetative and reproductive growth. As well, the onset of leaf senescence in the DHS-suppressed plants was delayed by approximately 1 week, but there was no change in the timing of bolting. In addition, there was no evidence for the negative pleiotropic effects, including stunted reproductive growth and reduced seed yield, noted previously for transgenic plants in which DHS was constitutively suppressed. The results indicate that DHS plays a pivotal role in both growth and senescence.

3' Untranslated Regions↗
PubMed1995

Evidence for cross-pathway regulation of metabolic gene expression in plants.

In Arabidopsis thaliana, blocking histidine biosynthesis with a specific inhibitor of imidazoleglycerol-phosphate dehydratase caused increased expression of eight genes involved in the biosynthesis of aromatic amino acids, histidine, lysine, and purines. A decrease in expression of glutamine synthetase was also observed. Addition of histidine eliminated the gene-regulating effects of the inhibitor, demonstrating that the changes in gene expression resulted from histidine-pathway blockage. These results show that plants are capable of cross-pathway metabolic regulation.

Arabidopsis↗
PubMed2002

The Commelina yellow mottle virus promoter drives companion-cell-specific gene expression in multiple organs of transgenic tobacco.

Previous work has demonstrated that some endogenous plant gene promoters are active in selective companion cells of the phloem, depending on organ types and developmental stages. Here we report that the Commelina yellow mottle virus (CoYMV) promoter is active in the companion cells of leaves, stems and roots of transgenic Nicotiana tabacum cv. Xanthi NN, using beta-glucuronidase (GUS) as a reporter. Thus, the CoYMV promoter has a broad organ specificity. This promoter can be useful in molecular studies on the functions of companion cells in many aspects of phloem biology, such as regulation of long-distance transport, macromolecular traffic, plant development and interaction with pathogens. It may also be useful in engineering crops that produce specific gene products in the companion cells to block long-distance movement of pathogens.

Gene Expression Regulation, Plant↗
PubMed2004

Activation of a mitogen-activated protein kinase cascade induces WRKY family of transcription factors and defense genes in tobacco.

Mitogen-activated protein kinase (MAPK) cascades are important signaling modules in eukaryotic cells that convert signals generated from the receptors/sensors to cellular responses. Upon activation, MAPKs can be translocated into nuclei where they phosphorylate transcription factors, which in turn activate gene expression. We recently identified NtMEK2, a tobacco MAPK kinase, as the upstream kinase of SIPK and WIPK, two well-characterized tobacco stress-responsive MAPKs. In the conditional gain-of-function NtMEK2DD transgenic tobacco plants, the activation of endogenous SIPK and WIPK by NtMEK2DD induces several groups of defense genes, including 3-hydroxy-3-methlyglutaryl CoA reductase (HMGR), basic pathogenesis related (PR) genes, systemic acquired resistance gene 8.2 (Sar 8.2), and harpin-induced gene1 (Hin1). To identify the transcription factor(s) involved in the activation of these defense genes, we performed gel-mobility shift assays using nuclear extracts from NtMEK2DD plants. Among the common cis-acting elements present in the promoters of defense-related genes, we observed a strong increase in the binding activity to the W box in nuclear extracts from the NtMEK2DD plants but not the control NtMEK2KR plants. The elevated W-box-binding activity in the nuclear extracts cannot be reversed by phosphatase treatment, excluding the possibility of a direct phosphorylation regulation of WRKY transcription factors by SIPK/WIPK. Instead, we observed a rapid increase in the expression of several WRKY genes in the NtMEK2DD plants. These results suggest that the increase in W-box-binding activity after SIPK/WIPK activation is a result of WRKY gene activation, and the NtMEK2-SIPK/WIPK cascade is involved in regulating the expression of genes ranging from transcription factors to defense genes further downstream during plant defense responses.

Base Sequence↗
PubMed1998

A bHLH transcription factor mediates organ, region and flower type specific signals on dihydroflavonol-4-reductase (dfr) gene expression in the inflorescence of Gerbera hybrida (Asteraceae).

The angiosperm family Asteraceae is characterized by composite inflorescences, which are highly organized structures consisting of different types of flowers. In order to approach the control of floral organ differentiation in Asteraceae at molecular level, we are studying regulation of flavonoid biosynthesis in Gerbera hybrida. Dihydroflavonol-4-reductase (dfr) expression is regulated according to anthocyanin pigmentation patterns in all tested gerbera varieties at several anatomical levels. We have isolated a promoter for one of the dfr genes, Pgdfr2. Gerbera plants transgenic for a Pgdfr2-uidA construct reveal that the activity of the Pgdfr2 promoter from one variety follows the pigmentation in other varieties which have different color patterns. It is thus evident that the observed complex regulation of dfr expression occurs in trans. In order to identify the trans-acting regulators, we isolated a cDNA (gmyc1) homologous to the previously characterized genes encoding bHLH-type regulators of the anthocyanin pathway in plants. The expression of gmyc1 in different varieties suggests that it has a major role in regulating dfr activity in corolla and carpel, but not in pappus and stamen. Specifically in gerbera, the identical patterns of gmyc1 and dfr expression in corolla tissue suggest that GMYC1 also regulates dfr expression in a region and flower type specific manner. Our studies show that in gerbera GMYC1-dfr interaction is part of several developmental processes characteristic for Asteraceae (such as specification of flower types across the composite inflorescence), whereas in other processes (such as differentiation of sepal as pappus) other regulators control dfr expression to determine the spatial specificity.

Alcohol Oxidoreductases↗
PubMed2000

In synergy with various cis-acting elements, plant insterstitial telomere motifs regulate gene expression in Arabidopsis root meristems.

The telo-box, an interstitial telomere motif, was shown to regulate gene expression in root meristems, in synergy with a cis-acting element involved in the activation of expression of plant eEF1A genes, encoding the translation elongation factor EF1A, and of several ribosomal protein genes. We demonstrate here that the telo-box is also required for transcription activation by two other cis elements present within the promoter of genes encoding the acidic ribosomal protein rp40 and the proliferating cell nuclear antigen respectively. The control of gene expression by telo-boxes during cell cycle progression in Arabidopsis root meristems is discussed. A parallel is drawn with the function of telomeric sequences in Saccharomyces cerevisiae.

Arabidopsis↗
PubMed1999

Creation of ecdysone receptor chimeras in plants for controlled regulation of gene expression.

Transformation with a chimeric receptor containing the glucocorticoid transactivation and DNA-binding domains fused to an ecdysteroid receptor ligand-binding domain permits ecdysone agonist-inducible gene expression in monocotyledonous plant cells. The inducible system is based on the specific activation of a chimeric receptor containing the ligand-binding domain of the Heliothis virescens ecdysteroid receptor and the inducer RH5992 (a 20-hydroxyecdysone agonist). RH5992 is an non-steroidal agrochemical with a high specificity for lepidopteran ecdysone receptors. Addition of RH5992 to transformed cells results in high levels of inducible expression in a ligand-specific manner, particularly when the effector receptor is coupled to the strong transactivator VP16. A chimeric construct containing the Drosophila ecdysone ligand-binding domain failed to activate reporter gene activity with RH5992, while activation was observed in the presence of muristeroneA. The system described provides the basis for an inducible gene expression system that is compatible with agricultural use.

Chimera↗
PubMed2004

Tobacco genes induced by the bacterial effector protein AvrPto.

The type III effector protein AvrPto acts as a virulence factor in susceptible plants lacking a cognate resistance gene but triggers hypersensitive response and disease resistance in tomato plants carrying the Pto gene or in tobacco plants carrying an unknown resistance gene. To assist the characterization of cellular responses caused by AvrPto in the plant, a pathogen-free system was adopted to isolate genes up-regulated 12 h after induced expression of AvrPto. By using subtraction cloning and transgenic tobacco plants expressing avrPto as a transgene, we isolated 125 nonredundant cDNA clones that represent avrPto-response genes (ARG). In addition to genes that are known to be induced by Pto-avrPto recognition, a number of new genes were also isolated. Most of ARG showed a specific induction in tobacco plants challenged with incompatible or nonhost pathogens. The use of an avrPto mutant that selectively eliminated the avrPto recognition in tobacco demonstrated that the ARG were induced in a highly specific manner by the avirulence, instead of the virulence activity of avrPto.

Bacterial Proteins↗