SEARCH · PubMed Health

Results for “GIBBERELLINS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14Linked to original sources

PubMed1992

Gibberellin-responsive elements in the promoter of a barley high-pI alpha-amylase gene.

Deletion analysis has previously shown that the major gibberellic acid (GA)- and abscisic acid (ABA)-responsive elements in the promoter of a high-pI alpha-amylase gene of barley are located downstream of -174 (Jacobsen and Close, 1991). We have used transient expression assays in barley aleurone protoplasts to identify sequences between -174 and +53 that confer GA and ABA responsiveness on expression of a beta-glucuronidase reporter gene. Using alpha-amylase promoter fragments and synthetic oligonucleotides fused to minimal promoters, we have shown that the hormone-responsive region is located between -174 and -108. A single copy of this region fused to a minimal alpha-amylase promoter (-41) conferred both GA- and ABA-responsive expression on the reporter gene comparable to the positive control, Am(-174)IGN. Multiple copies of this region were able to activate even greater levels of expression. Site-directed mutagenesis was used to determine the functional importance of the conserved motifs (-169pyrimidine box, -143TAACAAA box, and -124TATCCAC box) and nonconserved intervening sequences within the region between -174 and -108. Our results showed that both the TAACAAA and TATCCAC boxes play an important role in GA-regulated expression. We propose that the TAACAAA box is a gibberellin response element, that the TATCCAC box acts cooperatively with the TAACAAA box to give a high level of GA-regulated expression, and that together these motifs form important components of a gibberellin response complex in high-pI alpha-amylase genes. The TAACAAA box also appears to be the site of action of ABA.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

PubMed1992

Definition and functional implications of gibberellin and abscisic acid cis-acting hormone response complexes.

The mechanisms by which cis-acting hormone response elements affect transcription is unclear. In this study, we demonstrated that a second "coupling element," identified as O2S, must be present to allow a single copy of either the gibberellin response element (GARE) or the abscisic acid response element (ABRE) to mediate their hormonal effects in the barley Amy32b alpha-amylase gene promoter. The interactive effects of the O2S and the GARE are constrained positionally and spatially; thus, together they form a gibberellin response complex (GARC). The absolute requirement of the O2S for function of the ABRE demonstrates that these together form an abscisic acid response complex (ABRC). A second copy of the GARE can substitute for the O2S in the GARC, but only in one orientation. By expressing the GARC-containing and ABRC-containing promoters in developing aleurone tissue, we showed that hormonal effects prevent alpha-amylase gene expression during the second half of grain development, but other mechanisms suppress expression earlier. Our results suggest that the specific sequence serving as a coupling element in a given gene promoter will greatly affect where and when the GARE or ABRE will be able to regulate transcription.

Abscisic Acid↗

PubMed1992

A gibberellin response complex in cereal alpha-amylase gene promoters.

The Amy32b gene is a representative member of a closely related family of alpha-amylase genes expressed under hormonal control in aleurone layers of barley grains. Transcription of this gene is induced by gibberellin (GA) and suppressed by abscisic acid. In this study, we functionally defined the promoter elements of the Amy32b gene that govern the developmental and hormonal control of its expression in aleurone. Two functionally distinct yet physically associated elements are essential: a gibberellin response element mediates regulation by GA and abscisic acid, and an Opaque-2 binding sequence (O2S) is thought to interact with a barley homolog of the maize endosperm-specific transcriptional regulator Opaque-2. An additional element CCTTTT, which with the O2S forms part of a canonical "endosperm box," is important in modulating the absolute level of expression of the Amy32b promoter, as is another separate, highly conserved element TATCCATGCAGTG.

Abscisic Acid↗

PubMed1993

Mutations at the SPINDLY locus of Arabidopsis alter gibberellin signal transduction.

Three independent recessive mutations at the SPINDLY (SPY) locus of Arabidopsis confer resistance to the gibberellin (GA) biosynthesis inhibitor paclobutrazol. Relative to wild type, spy mutants exhibit longer hypocotyls, leaves that are a lighter green color, increased stem elongation, early flowering, parthenocarpy, and partial male sterility. All of these phenotypes are also observed when wild-type Arabidopsis plants are repeatedly treated with gibberellin A3 (GA3). The spy-1 allele is partially epistatic to the ga1-2 mutation, which causes GA deficiency. In addition, the spy-1 mutation can simultaneously suppress the effects of the ga1-2 mutation and paclobutrazol treatment, which inhibit different steps in the GA biosynthesis pathway. This observation suggests that spy-1 activates a basal level of GA signal transduction that is independent of GA. Furthermore, results from GA3 dose-response experiments suggest that GA3 and spy-1 interact in an additive manner. These results are consistent with models in which the SPY gene product regulates a portion of the GA signal transduction pathway.

Alleles↗

PubMed1994

The Arabidopsis GA1 locus encodes the cyclase ent-kaurene synthetase A of gibberellin biosynthesis.

The first committed step in the gibberellin (GA) biosynthetic pathway is the conversion of geranylgeranyl pyrophosphate (GGPP) through copalyl pyrophosphate (CPP) to ent-kaurene catalyzed by ent-kaurene synthetases A and B. The ga1 mutants of Arabidopsis are gibberellin-responsive male-sterile dwarfs. Biochemical studies indicate that biosynthesis of GAs in the ga1 mutants is blocked prior to the synthesis of ent-kaurene. The GA1 locus was cloned previously using the technique of genomic subtraction. Here, we report the isolation of a nearly full-length GA1 cDNA clone from wild-type Arabidopsis. This cDNA clone encodes an active protein and is able to complement the dwarf phenotype in ga1-3 mutants by Agrobacterium-mediated transformation. In Escherichia coli cells that express both the Arabidopsis GA1 gene and the Erwinia uredovora gene encoding GGPP synthase, CPP was accumulated. This result indicates that the GA1 gene encodes the enzyme ent-kaurene synthetase A, which catalyzes the conversion of GGPP to CPP. Subcellular localization of the GA1 protein was studied using 35S-labeled GA1 protein and isolated pea chloroplasts. The results showed that the GA1 protein is imported into and processed in pea chloroplasts in vitro.

Alkyl and Aryl Transferases↗

PubMed2006

gid1, a gibberellin-insensitive dwarf mutant, shows altered regulation of probenazole-inducible protein (PBZ1) in response to cold stress and pathogen attack.

A recessive gibberellin (GA)-insensitive dwarf mutant of rice, gibberellin-insensitive dwarf1 (gid1), has been identified, which shows a severe dwarf phenotype and contains high concentrations of endogenous GA. To elucidate the function of gid1, proteins regulated downstream of gid1 were analysed using a proteomic approach. Proteins extracted from suspension-cultured cells of gid1 and its wild type were separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Of a total of 962 proteins identified from the suspension-cultured cells, 16 were increased and 14 were decreased in gid1 compared with its wild type. Among the proteins hyper-accumulated in gid1 were osmotin, triosephosphate isomerase, probenazole inducible protein (PBZ1) and pathogenesis-related protein 10. Of these four genes, only the expression of PBZ1 was increased by exogenous GA3 application. Expression of this gene was also enhanced in shoots of the wild type by cold stress or by rice blast fungus infection. Under normal growth conditions, there was more PBZ1 protein in gid1 than in the wild type. In addition, gid1 showed increased tolerance to cold stress and resistance to blast fungus infection. The entcopalyl diphosphate synthase (OsCPS) genes, which encode enzymes at the branch point between GA and phytoalexin biosynthesis, were expressed differentially in gid1 relative to the wild type. Specifically, OsCPS1, which encodes an enzyme in the GA biosynthesis pathway, was down-regulated and OsCPS2 and OsCPS4, which encode enzymes in phytoalexin biosynthesis, were up-regulated in gid1. These results suggest that the expression of PBZ1 is regulated by GA signalling and stress stimuli, and that gid1 is involved in tolerance to cold stress and resistance to blast fungus.

Abscisic Acid↗

PubMed2004

GID2, an F-box subunit of the SCF E3 complex, specifically interacts with phosphorylated SLR1 protein and regulates the gibberellin-dependent degradation of SLR1 in rice.

The phytohormone gibberellin (GA) controls growth and development in plants. Previously, we identified a rice F-box protein, gibberellin-insensitive dwarf2 (GID2), which is essential for GA-mediated DELLA protein degradation. In this study, we analyzed the biological and molecular biological properties of GID2. Expression of GID2 preferentially occurred in rice organs actively synthesizing GA. Domain analysis of GID2 revealed that the C-terminal regions were essential for the GID2 function, but not the N-terminal region. Yeast two-hybrid assay and immunoprecipitation experiments demonstrated that GID2 is a component of the SCF complex through an interaction with a rice ASK1 homolog, OsSkp15. Furthermore, an in vitro pull-down assay revealed that GID2 specifically interacted with the phosphorylated Slender Rice 1 (SLR1). Taken these results together, we conclude that the phosphorylated SLR1 is caught by the SCFGID2 complex through an interacting affinity between GID2 and phosphorylated SLR1, triggering the ubiquitin-mediated degradation of SLR1.

Cullin Proteins↗

PubMed2005

Hormonal regulation of gluconeogenesis in cereal aleurone is strongly cultivar-dependent and gibberellin action involves SLENDER1 but not GAMYB.

Storage oil is a major constituent in the cereal aleurone layer. The aim of this study was to investigate how gibberellin (GA) and abscisic acid (ABA) regulate conversion of oil to sugar in barley aleurone. The activity of the glyoxylate cycle enzyme isocitrate lyase (ICL) was surveyed in eight barley cultivars. Surprisingly, some cultivars do not require GA for the induction of ICL (e.g. Himalaya), whereas some do (e.g. Golden Promise). Furthermore, in Golden Promise, GA also stimulates triacylglycerol breakdown and enhances the net flux of carbon from acetate to sugar. In contrast, ABA strongly represses ICL activity and the flux of carbon from oil to sugar in both Golden Promise and Himalaya. Biolistics using a promoter reporter showed that GA and ABA regulate ICL at the level of transcription. Studies using barley and rice mutants and pharmacological agents show that GA-dependent induction of ICL activity is mediated by SLENDER1 and requires cGMP, but does not involve the transcription factor GAMYB. Gibberellin and ABA therefore act antagonistically to regulate gluconeogenesis in the aleurone layer as well as controlling the production and secretion of hydrolases into the starchy endosperm. We suggest that the variation between different barley cultivars might be a result of selective breeding to alter seed dormancy.

Abscisic Acid↗

PubMed2005

Structure, epitope mapping, and docking simulation of a gibberellin mimic peptide as a peptidyl mimotope for a hydrophobic ligand.

Using NMR spectroscopy and simulated annealing calculations, we determined the solution structure of the disulfide-linked cyclized decapeptide ACLPWSDGPC (SD), which is bound to an anti-(gibberellin A(4)) mAb 4-B8(8)/E9 and was found to be the first peptidyl mimotope for a hydrophobic ligand. The resulting structure of the peptide showed a beta-turn-like conformation in residues three to seven and the region converges well (average rmsd 0.54 A). The binding activity and the epitopes of the peptide to the antibody were assessed using saturation transfer difference (STD)-NMR experiments. We also conducted docking simulations between the peptide and the mAb to determine how the peptide is bound to the mAb. Resonances around the beta-turn-like conformation of peptide SD (residues 3-5) showed strong STD enhancement, which agreed well with results from docking simulation between peptide SD and the mAb. Together with the commonality of amino acid residues of the mAb involved in interactions with gibberellin A(4) (GA(4)) and peptide SD, we concluded that peptide SD is bound to the antigen-binding site of mAb 4-B8(8)/E9 as a GA(4) mimic, confirming evidence for the existence of peptide mimics even for hydrophobic ligands.

Amino Acid Sequence↗

PubMed1988

Induction of neoplasms in the Egyptian toad Bufo regularis by gibberellin A3.

Force feeding the Egyptian toads (Bufo regularis) with gibberellin A3 (10 ppm) twice a week for 5 months induced neoplasms in 8 out of 50 (16%) experimental animals. Primary tumours developed in the liver (hepatocellular carcinomas). Two secondary tumours in the kidneys and another 2 in the ovaries of toads developed due to metastases from the hepatocellular carcinomas. The results show that gibberellic acid (gibberellin A3) has a carcinogenic effect in the Egyptian toads.

Animals↗

PubMed2026

Exogenous gibberellin promotes lateral branch development in stumping Pinus yunnanensis by regulating endogenous hormones and TCP genes.

While plant stumping can break apical dominance, promote lateral branching, and thereby increase yield, a significant technical challenge remains in further enhancing the coppicing regrowth capacity after stumping. This study used one-year-old Pinus yunnanensis Franch seedlings as subjects. Through exogenous application of gibberellin 3 (GA3) and Paclobutrazol (PAC), it investigated the regulatory role of gibberellin (GA) in sprouting and identified TCP genes related to branching within the GA pathway. Results indicate that exogenous hormone treatments altered endogenous hormone levels in P. yunnanensis seedlings. Exogenous GA3 treatment significantly increased endogenous IPA, ABA, GA3, GA1, SA, and SAG content. Correlation analysis with sprout number revealed a positive relationship between endogenous hormones and sprout number, indicating that exogenous GA3 significantly influenced sprout number. After hormone application, the cumulative number of sprouts increased with seedling age across all treatments. Therefore, to further investigate whether changes in sprout number were caused by gene alterations in the GA signaling pathway, this study analyzed the GA signaling pathway and its associated transcription factors. Fifteen TCP family members were screened from the P. yunnanensis transcriptome, phylogenetically classified into Class I and Class II subfamilies. Conserved motif sites within the Class II family co-occurred, exhibiting high conservation. Genes from the Class II subfamily were cloned, and their differential expression across various tissues was analyzed via real-time quantitative PCR. Expression patterns under different hormone treatments were also examined. Our results reveal that PyTCP4, PyTCP6, and PyTCP20 are significantly upregulated by PAC (a GA synthesis inhibitor) and show strong negative correlations with sprouts number, while GA3 treatment partially alleviates this effect. These findings provide direct evidence that TCP transcription factors act as repressors of shoot branching, linking their hormone-responsive expression to the regulation of sprouts formation in P. yunnanensis. These results indicate that TCP transcription factors play a crucial role in shoot and root emergence, with their expression influenced by exogenous hormones, thereby affecting the growth and development of emerging shoots and roots. This provides a reference and basis for analyzing the expression patterns and functions of TCP genes in P. yunnanensis, facilitating further research into their functions.

Gibberellins↗

PubMed1999

Preparation and application of anti-idiotypic antibody against anti-gibberellin A4 antibody.

A monoclonal anti-idiotypic antibody was raised against anti-gibberellin A4 (GA4) antibody, which recognizes biologically active gibberellins such as GA1 and GA4 specifically. Amino acid sequences of variable regions of both anti-GA4 and anti-idiotypic antibodies were analyzed. By using the property of the anti-idiotypic antibody to compete with GA1/4 in binding to the anti-GA4 antibody, we successfully applied the anti-idiotypic antibody to ELISA as a tracer for measuring GA1/4. The single-chain Fv (scFv) gene of the anti-idiotypic antibody was constructed, and scFv expressed in E. coli showed binding activity to anti-GA4 antibody. These results suggest the possible application of anti-idiotypic antibody as a handy and stable source of an enzymatic tracer for ELISA by production of fusion protein of the scFv and an appropriate enzyme.

Amino Acid Sequence↗

PubMed2004

Identification of peptidyl mimics of bioactive gibberellin recognized by an antibody.

We screened a phage display peptide library for peptidyl mimotopes of gibberellin against anti-bioactive gibberellin antibody. The peptides obtained were grouped into two homologous sequences and their binding to the antibody was put in competition with free GA(4) but not with GA(4) methylester, suggesting that the peptides behave as mimics of GA(4). As an application, the phage display peptide was shown to work as a tracer for enzyme-linked immunosorbent assay (ELISA) analysis of GA(4).

Amino Acid Sequence↗

PubMed2004

Gibberellin induces alpha-amylase gene in seed coat of Ipomoea nil immature seeds.

Two full-length cDNAs encoding gibberellin 3-oxidases, InGA3ox1 and InGA3ox2, were cloned from developing seeds of morning glory (Ipomoea nil (Pharbitis nil) Choisy cv. Violet) with degenerate-PCR and RACEs. The RNA-blot analysis for these clones revealed that the InGA3ox2 gene was organ-specifically expressed in the developing seeds at 6-18 days after anthesis. In situ hybridization showed the signals of InGA3ox2 mRNA in the seed coat, suggesting that active gibberellins (GAs) were synthesized in the tissue, although no active GA was detected there by immunohistochemistry. In situ hybridization analysis for InAmy1 (former PnAmy1) mRNA showed that InAmy1 was also synthesized in the seed coat. Both InGA3ox2 and InAmy1 genes were expressed spatially overlapped without a clear time lag, suggesting that both active GAs and InAmy1 were synthesized almost simultaneously in seed coat and secreted to the integument. These observations support the idea that GAs play an important role in seed development by inducing alpha-amylase.

Amino Acid Sequence↗

PubMed2005

Preparation of functional single-chain antibodies against bioactive gibberellins by utilizing randomly mutagenized phage-display libraries.

Screening randomly mutagenized proteins displayed on a phage surface by biopanning is a powerful strategy to obtain evolved clones with improved properties such as higher stability and functionality. We utilized this method to overcome the problem that functional single-chain antibodies against active gibberellins, a class of plant hormones, can not be prepared by some of the conventional methods. Single-chain antibody libraries with random mutations were constructed from two independent anti-bioactive gibberellin monoclonal antibody lines in a phagemid vector, so that the mutagenized scFvs were expressed in a phage-displayed form upon helper phage infection. From both libraries, scFv clones with binding activity to GA(4) were successfully obtained by successive rounds of biopanning against BSA-GA(4), the original immunogen. The results are highly suggestive that this approach might be a general solution when a single-chain antibody does not show binding activity. We found further that a ribosomal frameshift to complement a nonsense mutation frequently occurred in an amber suppressor strain of E. coli TG1, resulting in the display of a functional antibody, while such a nonsense mutant failed to produce a soluble antibody in a non-amber suppressor strain. This result explains at least partly why single-chain antibodies are sometimes functional only in a phage-displayed form, not in a soluble form.

Amino Acid Sequence↗

PubMed1998

SPINDLY's role in the gibberellin response pathway.

The SPINDLY (SPY) locus of Arabidopsis thaliana is believed to be involved in gibberellin (GA) signal transduction. The six known mutations at this locus cause a phenotype that is consistent with constitutive activation of the GA signal transduction pathway. spy alleles are epistatic to gai, a mutation conferring gibberellin-insensitivity, indicating that SPY acts as a negative regulator of GA signal transduction, downstream of GAI. SPY was cloned using a T-DNA insertion in the spy-4 allele. SPY encodes a 914 amino acid protein with an N-terminal TPR region (a likely protein-protein interaction domain) and a novel C-terminal domain. The spy mutants show that both the N- and C-terminal domains of SPY are functionally important, spy-4 is likely to be a null allele and displays some morphological defects not seen in the other alleles. A 35S:SPY construct rescues the spy mutant phenotype, but does not show any gain-of-function SPY phenotypes. Smaller constructs overexpressing different domains of the SPY protein have no effect on plant development.

Alleles↗

PubMed2001

Morphological changes in garlic (Allium sativum L.) microbulblets during dormancy and sprouting as related to peroxidase activity and gibberellin A3 content.

The aim of this work was to study the physiological mechanisms of dormancy and sprouting during post-harvest of garlic (Allium sativum L.) microbulblets produced by meristem culture of garlic seed cloves. The morphological changes occurring in garlic microbulblets were assessed from harvest till sprouting in relation with peroxidase activity and levels of gibberellins. Also the effect of a cold treatment (30 days at 4 degrees C) given 30 days after harvest was studied. The results showed that during the state of dormancy in garlic microbulblets formation of the leaf primordia and vascular differentiation of the storage leaf occurred, while increases of peroxidase activity and low levels of GA3 (the only active gibberellin identified) were found. At the end of dormancy the sprouting channel was formed, vascular differentiation established, and peaks of soluble peroxidase activity as well as of GA3 were observed. At day 90 post-harvest, garlic microbulblets showed physiologically mature and able to sprout. Further on, bud expansion and decrease of GA3 levels characterized sprouting of the microbulblets. The cold treatment enhanced GA3 levels and anticipated the sprouting process.

Cell Differentiation↗

PubMed2004

[Effect of gibberellin on direct regeneration of floral buds from young flower buds in Sinningia speciosa Hiern].

The phenomena of direct regeneration of floral buds on young flower bud and sepal cultures in vitro were observed in Sinningia speciosa Hiern. The gibberellin concentration in medium was very important for inducing the direct regeneration of floral buds. No direct floral bud was regenerated when the concentration of gibberellin (GA) supplemented in medium was equal to or less than 0.5 mg/L. The young floral buds and sepals inoculated on modified Murashige and Skoog (MS) medium supplemented with 1.0-1.5 mg/L GA and 0.1 mg/L 6-benzylaminopurine (BA) for 40 days produced floral buds directly on the surface of the sepals. There were two types of the floral buds regenerated directly: one was only with floral buds, which was up to 14.3%; the other was with both floral and vegetative buds, which was up to 28.6%. The effect of exogenous GA on the formation of floral buds in Sinningia cultured in vitro is discussed.

Flowers↗