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《Acta Genetica Sinica》2010,(1)
Gibberellin (GA) 2-oxidase plays a key role in the GA catabolic pathway through 2β-hydroxylation.In the present study,we isolated a CaMV 35S-enhancer activation tagged mutant,H032.This mutant exhibited a dominant dwarf and GA-deficient phenotype,with a final stature that was less than half of its wild-type counterpart.The endogenous bioactive GAs are markedly decreased in the H032 mutant,and application of bioactive GAs (GA3 or GA4) can reverse the dwarf phenotype.The integrated T-DNA was detected 12.8 kb u... 相似文献
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Jian Huang Ding Tang Yi Shen Baoxiang Qin Lilan Hong Aiqing You Ming Li Xin Wang Hengxiu Yu Minghong Gu Zhukuan Cheng 《遗传学报》2010,37(1):23-36
Gibberellin (GA) 2-oxidase plays a key role in the GA catabolic pathway through 2β-hydroxylation.In the present study,we isolated a CaMV 35S-enhancer activation tagged mutant,H032.This mutant exhibited a dominant dwarf and GA-deficient phenotype,with a final stature that was less than half of its wild-type counterpart.The endogenous bioactive GAs are markedly decreased in the H032 mutant,and application of bioactive GAs (GA3 or GA4) can reverse the dwarf phenotype.The integrated T-DNA was detected 12.8 kb upstream of the OsGA2ox6 in the H032 genome by TAIL-PCR.An increased level of OsGA2ox6 mRNA was detected at a high level in the H032 mutant,which might be due to the enhancer role of the CaMV 35S promoter.RNAi and ectopic expression analysis of OsGA2ox6 indicated that the dwarf trait and the decreased levels of bioactive GAs in the H032 mutant were a result of the up-regulation of the OsGA2ox6 gene.BLASTP analysis revealed that OsGA2ox6 belongs to the class III of GA 2-oxidases,which is a novel type of GA2ox that uses C20-GAs (GA12 and/or GA53) as the substrates.Interestingly,we found that a GA biosynthesis inhibitor,paclobutrazol,positively regulated the OsGA2ox6 gene.Unlike the over-expression of OsGA2ox1,which led to a high rate of seed abortion,the H032 mutant retained normal flowering and seed production.These results indicate that OsGA2ox6 mainly affects plant stature,and the dominant dwarf trait of the H032 mutant can be used as an efficient dwarf resource in rice breeding. 相似文献
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《Plant science》1987,53(1):11-19
The effect of exogenously applied gibberellic (GA3) acid on developmental processes in dwarf pea and dwarf maize seedlings was studied. Plants responded to the phytohormone by accelerated longitudinal growth rate and apparent shortening of developmental phases. Poly(A)-mRNA population isolated from gibberellin-treated pea or maize seedlings exhibited much higher translational activity per mRNA unit in the cell-free wheat germ system when compared with control, untreated plants. Analysis of in vitro translation products made by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS—PAGE) followed by autoradiography and densitometry revealed markedly increased overall intensity of the labelled polypeptide bands in addition to the new protein bands which started to appear in gibberellin-treated pea and maize seedlings while were still not detectable in the control plants of the same age. The banding pattern of translation products programmed by poly(A)-mRNA extracted from 2 days older untreated pea plants resembled that of the gibberellin-treated 2 days younger seedlings. It is concluded that gibberellic acid applied to dwarfs accelerates not exclusively the longitudinal growth of plants but also promotes their transition to the next developmental phases. 相似文献
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Masato Otani Jung-Min Yoon Seung-Hyun Park Tadao Asami Masatoshi Nakajima 《Bioorganic & medicinal chemistry letters》2010,20(14):4259-4262
The hydroxylation of gibberellin (GA) at the 2-position is known as the major cause of inactivation of GAs, whose reaction is catalyzed by 2-oxoglutarate dependent dioxygenases, also termed GA 2-oxidases (GA2oxs). To block GA catabolism in plants, a few chemicals can be used. To obtain novel inhibitors specific to GA2oxs, we performed in vitro random screenings by using 3H-16,17-dihydro-GA4 and recombinant Arabidopsis GA2ox2. As a result, one candidate, methyl 6-chloro-3H-1,2,3-benzodithiazole-4-carboxylate 2-oxide (CBTC), was selected from the screening, and was subjected to in-planta evaluations. CBTC promoted both the germination and elongation of Arabidopsis seedlings. This strongly suggests that CBTC inhibits GA2oxs in Arabidopsis with high specificity. 相似文献
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Mitchum MG Yamaguchi S Hanada A Kuwahara A Yoshioka Y Kato T Tabata S Kamiya Y Sun TP 《The Plant journal : for cell and molecular biology》2006,45(5):804-818
Gibberellin (GA) 3-oxidase, a class of 2-oxoglutarate-dependent dioxygenases, catalyzes the conversion of precursor GAs to their bioactive forms, thereby playing a direct role in determining the levels of bioactive GAs in plants. Gibberellin 3-oxidase in Arabidopsis is encoded by a multigene family consisting of at least four members, designated AtGA3ox1 to AtGA3ox4. It has yet to be investigated how each AtGA3ox gene contributes to optimizing bioactive GA levels during growth and development. Using quantitative real-time PCR analysis, we have shown that each AtGA3ox gene exhibits a unique organ-specific expression pattern, suggesting distinct developmental roles played by individual AtGA3ox members. To investigate the sites of synthesis of bioactive GA in plants, we generated transgenic Arabidopsis that carried AtGA3ox1-GUS and AtGA3ox2-GUS fusions. Comparisons of the GUS staining patterns of these plants with that of AtCPS-GUS from previous studies revealed the possible physical separation of the early and late stages of the GA pathway in roots. Phenotypic characterization and quantitative analysis of the endogenous GA content of ga3ox1 and ga3ox2 single and ga3ox1/ga3ox2 double mutants revealed distinct as well as overlapping roles of AtGA3ox1 and AtGA3ox2 in Arabidopsis development. Our results show that AtGA3ox1 and AtGA3ox2 are responsible for the synthesis of bioactive GAs during vegetative growth, but that they are dispensable for reproductive development. The stage-specific severe GA-deficient phenotypes of the ga3ox1/ga3ox2 mutant suggest that AtGA3ox3 and AtGA3ox4 are tightly regulated by developmental cues; AtGA3ox3 and AtGA3ox4 are not upregulated to compensate for GA deficiency during vegetative growth of the double mutant. 相似文献
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Orchard-grown dwarf apple (Malus domestica Borkh.) trees selected from a hybrid population were propagated by tissue culture but had a growth pattern similar to standard cv. Golden Delicious plants when grown at constant 27°C instead of the expected dwarf pattern of growth. Shoot elongation was markedly reduced, with or without gibberellin A1 (GA1) or GA4 treatment, when trees were grown in an environment where day temperature was maintained at 35°C for 2 h in a ramped regime (night 20°C day ramped to 35°C, held for 2 h and ramped down to 20°C night over a 14-h photoperiod). Application of GA1 or GA4 partially overcame growth retardation resulting from prior paclobutrazol treatment of both standard and dwarf trees grown at constant 27°C and of standard trees grown in the ramped environment. However, these GAs had no effect on paclobutrazol-treated or untreated dwarfs grown in the ramped regime. Gas chromatography-mass spectrometry with labelled internal standards was used to quantify GA1, GA3, GA8, GA19, GA20 and GA29 in extracts from standard and dwarf plants grown either at a constant 27°C or in a 20-30-20°C ramped temperature regime. Standard plants, which elongate quite rapidly in either environment, had similar levels of these GAs in both temperature regimes. The slowly growing dwarfs in the ramped temperature environment contained three times more GA19 than the rapidly elongating dwarfs grown at 27°C. The concentrations of the other GAs were reduced to ca 40% or less in plants grown in the ramped temperature regime compared with those grown at 27°C. These data suggest that shoot elongation of dwarf plants is sensitive to elevated temperatures both as a result of reduced responsiveness to GAs and because of a reduction in the concentration of GA1, apparently as a result of a lower rate of conversion of GA19 to GA20. It is possible that the altered GA metabolism may be a consequence of the change in GA sensitivity. 相似文献
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Gibberellin structure and function: biological activity and competitive inhibition of gibberellin 2- and 3-oxidases 总被引:1,自引:0,他引:1
Some gibberellin (GA) analogues, especially with C-16,17 modifications of GA(5), can inhibit growth of plants apparently by acting as competitors with the endogenous substrate of GA biosynthetic enzymes. Here, we directly confirm the competitive action of GA derivatives but also show that some analogues may retain significant bioactivity. A recombinant 3-oxidase from pea, which converts GA(20) to bioactive GA(1), was inhibited by GA(5), and 16,17-dihydro-GA(5) derivatives, especially if the C-17 alkyl chain length was increased by up to three carbons or if the C-13 hydroxyl was acetylated. Genetic confirmation that GA(5) analogues target 3-oxidases in vivo was provided by comparing the growth response of a WT (LE) pea with a 3-oxidase mutant (le-1). Two pea 2-oxidases that inactivate bioactive GAs, were inhibited by GA(1) and GA(3) but were generally insensitive to GA(5) analogues. alpha-Amylase production by barley half-seeds in response to GA analogues provided a method to study their action when effects on GA biosynthesis were excluded. This bioactivity assay showed that 16,17-dihydro GA(5) analogues have some inherent activity but mostly less than for GA(5) (5-50-fold), which in turn was 100-fold less active than GA(1) and GA(3). However, although C-17 alkyl derivatives with one or two added carbons showed little bioactivity and were purely 3-oxidase inhibitors, adding a third carbon (the 17-n-propyl-16,17-dihydro GA(5) analogue) restored bioactivity to that of GA(5). Furthermore, this analogue has lost its capacity to inhibit stem elongation of Lolium temulentum (Mander et al., Phytochemistry 49:1509-1515, 1998a), although it strongly inhibits the 3-oxidase. Thus, the effectiveness of a GA derivative as a growth retardant will reflect the balance between its bioactivity and its capacity to inhibit the terminal enzyme of GA biosynthesis. The weaker growth inhibition in dicots including pea (approximately 10%) than in monocots such as L. temulentum (>35%) is suggestive of taxonomic differences in the bioactivity of GAs and/or their effects on GA biosynthesis. 相似文献
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Molecular characterisation of gibberellin 20-oxidases. Structure-function studies on recombinant enzymes and chimaeric proteins 总被引:1,自引:0,他引:1
Theo Lange Carsten Kegler Peter Hedden y L. Phillips Jan E. Graebe 《Physiologia plantarum》1997,100(3):543-549
Gibberellin (GA) 20-oxidases are multifunctional enzymes that catalyse reactions at an important branch point in the GA biosynthetic pathway. These enzymes oxidise the C-20 methyl group of a diterpene carboxylic acid precursor (e.g. GA12) to form an alcohol (in our case GA15-open lactone) and an aldehyde (GA24). The aldehyde is either oxidised to a tricarboxylic acid (GA25) or, with loss of carbon-20 and lactonisation, to a C19-GA (GA9). This branching is interesting to study, because C19-GA derivatives function as plant hormones in different tissues, whereas the C20-GA tricarboxylic acids have no known function. We have constructed chimaeric proteins by combining a GA 20-oxidase from immature seeds of Cucurbita maxima L., which produces mainly C-20 carboxylic acids, with a 20-oxidase from Marah macrocarpus immature seeds, which forms predominantly CC19-GAs. The cDNAs encoding these two very similar 20-oxidases were digested with restriction endonucleases Van 911. Bcl 1, and Bsa WI, and six chimaeric sequences were produced by recombination of the DNA fragments. The pCM1 -construct was obtained by exchanging nt 303–809 of the Cucurbita cDNA with the homologous DNA from the March 20-oxidase. In pCM2, pCM3, pCM4, pCM5 and pCM6, nt 810–992, nt 993–end, nt 303–992, nt 810–end, and nt 311–end were exchanged, respectively. All constructs were cloned in a pUC18 vector and functionally expressed in E. coli NM522 cells. GA 20-oxidase activity was detectable in cell-lysates from the transformed E. coli, but the extent and kind of conversion depended on the construct. Highest conversion of GA12was found with pCM1 and pCM3, one-tenth of this conversion was observed with pCM5 and pCM6, and one-hundredth was obtained with the hybrid proteins from pCM2 and pCM4. With pCM2 and pCM4, neither the C19-end product, GA9, nor the C20-end product, GA25-was formed. However, after transformation with constructs pCM1, pCM3, pCM5 or pCM6. GA9accounted for 30, 40, 60 and 90%, respectively, of the end products formed. Thus, the segments originating from M. macrocarpus conferred upon the chimaeric proteins an increasing ability to direct the biosynthetic flow into C19-GAs in this order. Although GA24is the immediate precursor, much less end products were formed by using this substrate. 相似文献
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Radioactive gibberellin A5 (3H-GA5) was synthesized from gibberellic acid. When it was applied to dwarf peas grown in the dark, an average of 3% was converted to another acid gibberellin within 48 hours. The biological activity of the metabolite did not account for the response to applied GA5. GA5 is therefore assumed to be biologically active per se.3H-GA5 did not appear to form a stable complex with a macromolecule in pea shoots. When injected into dwarf pea pods, 3H-GA5 was readily metabolized by maturing seed to more water-soluble substances and to two other acidic compounds. This metabolism continued even throughout germination of the seed without reconversion of the metabolites to GA5. It is concluded that “bound” GA5 plays no part in the germination of dwarf pea seeds. 相似文献
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Park SH Nakajima M Hasegawa M Yamaguchi I 《Bioscience, biotechnology, and biochemistry》2005,69(8):1508-1514
Gibberellin-binding proteins (GBPs) were purified ca. 230,000 fold. The characteristics of adzuki GBP were examined and compared with those of a recombinant gibberellin 2-oxidase (rVaGA2oxA1) that was fused with glutathione S-transferase (GST). VaGA2oxA1 was most abundantly expressed in etiolated adzuki bean seedlings, and VaGA2oxA1 and GBPs from adzuki bean seedlings showed gibberellin-binding activity when incubated with 2-oxoglutarate and Co2+. Both rVaGA2oxA1 and partially purified GBPs from adzuki bean seedlings showed very similar selectivity to gibberellins in binding assays, where biologically active gibberellins such as GA4, GA3, GA7, and GA1 showed higher binding affinity than biologically inactive gibberellins such as GA8, GA34, and 3-epi-GA4. The polyclonal antibody raised against rVaGA2oxA1 cross-reacted with all rVaGA2oxs (rVaGA2oxA1, rVaGA2oxA2, rVaGA2oxB1, rVaGA2oxB2, and rVaGA2oxB3) whose cDNAs were cloned from adzuki bean seedlings. Treated with the antibody, the recombinants that originally showed gibberellin-binding activity lost both binding activity and enzymatic activity. In contrast to the recombinants, the gibberellin-binding activity of GBPs from adzuki bean seedlings was hardly affected by the antibody treatment. The GBPs showed very weak gibberellin 2-oxidase-like activity, and it was not affected by the antibody treatment either. These observations suggest that a major component that showed GA-binding activity was apparently different from any gibberellin 2-oxidase cloned from the seedlings. 相似文献
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Insertion of IS2 creates a novel ampC promoter in Escherichia coli 总被引:24,自引:0,他引:24
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Preparation of radioactive gibberellin a(1) and its metabolism in dwarf peas 总被引:11,自引:10,他引:1
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Kende H 《Plant physiology》1967,42(11):1612-1618
Gibberellin A1-3,4-3H was prepared by selective catalytic reduction of gibberellic acid with a mixture of tritium and hydrogen. 3H-GA1 was applied at physiological concentrations to dwarf peas and the metabolism of the hormone was investigated. 3H-GA1 was converted to an acidic, biologically active compound. Radioactive but biologically inactive compounds were also found in the neutral fraction and could not be converted to acidic gibberellins by hydrolysis. No attachment of gibberellin to any macromolecular fraction was evident. 相似文献
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Changes in jasmonate and gibberellin levels during development of potato plants (Solanum tuberosum) 总被引:1,自引:0,他引:1
Among the multiple environmental signals and hormonal factors regulatingpotato plant morphogenesis and controlling tuber induction, jasmonates (JAs)andgibberellins (GAs) are important components of the signalling pathways in theseprocesses. In the present study, with Solanum tuberosum L.cv. Spunta, we followed the endogenous changes of JAs and GAs during thedevelopmental stages of soil-grown potato plants. Foliage at initial growthshowed the highest jasmonic acid (JA) concentration, while in roots the highestcontent was observed in the stage of tuber set. In stolons at the developmentalstage of tuber set an important increase of JA was found; however, in tubersthere was no change in this compound during tuber set and subsequent growth.Methyl jasmonate (Me-JA) in foliage did not show the same pattern as JA; Me-JAdecreased during the developmental stages in which it was monitored, meanwhileJA increased during those stages. The highest total amount of JAs expressed asJA+Me-JA was found at tuber set. A very important peak ofJA in roots was coincident with that observed in stolons at tuber set. Also, aprogressive increase of this compound in roots was shown during the transitionof stolons to tubers. Of the two GAs monitored, gibberellic acid(GA3) was the most abundant in all the organs. While GA1and GA3 were also found in stolons at the time of tuber set, noothermeasurements of GAs were obtained for stolons at previous stages of plantdevelopment. Our results indicate that high levels of JA and GAs are found indifferent tissues, especially during stolon growth and tuber set. 相似文献
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Tall peas var. Alaska and dwarf peas var. Progress No. 9 were grafted onto their own roots or reciprocally grafted to determine the rootstock effect on the growth of the stem. In all cases the grafted stems grew the same as their ungrafted controls regardless of which rootstock they were grown on. When similarly grafted plants were supplied with gibberellic acid, good graft unions did not inhibit its translocation. This evidence supports the thesis that the mechanism controlling stem growth in peas is located in the stem and that the roots have no direct control over this mechanism. 相似文献