Distinct and overlapping roles of two gibberellin 3-oxidases in Arabidopsis development
Distinct and overlapping roles of two gibberellin 3-oxidases in Arabidopsis development
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DOI：
10.1111/j.1365-313x.2005.02642.x
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发表时间：
2006-03-01
期刊：
影响因子：
7.2
通讯作者：
Sun, TP
中科院分区：
文献类型：
--
作者：
Mitchum, MG;Yamaguchi, S;Sun, TP
赤霉素（GA）3-氧化酶是一类依赖于2-酮戊二酸的双加氧酶，催化GA前体转化为具有生物活性的形式，从而直接决定植物体内GA的水平。拟南芥赤霉素3-氧化酶是由一个多基因家族编码的，该家族至少有4个成员，分别命名为AtGA 3 ox 1至AtGA 3 ox 4。目前还没有研究每个AtGA 3 ox基因如何在生长和发育过程中优化生物活性GA水平。使用实时定量PCR分析，我们已经表明，每个AtGA 3 ox基因表现出独特的器官特异性表达模式，这表明不同的发展所发挥的作用，个别AtGA 3 ox成员。为了研究植物中生物活性GA的合成位点，我们构建了携带AtGA 3 ox 1-GUS和AtGA 3 ox 2-GUS融合基因的转基因拟南芥。比较这些植物的GUS染色模式与AtCPS-GUS从以前的研究揭示了可能的物理分离的早期和晚期阶段的GA途径在根中。对ga 3 ox 1和ga 3 ox 2单突变体和ga 3 ox 1/ga 3 ox 2双突变体的表型特征和内源GA含量的定量分析揭示了AtGA 3 ox 1和AtGA 3 ox 2在拟南芥发育中的不同和重叠的作用。我们的研究结果表明，AtGA 3 ox 1和AtGA 3 ox 2负责营养生长过程中的生物活性GA的合成，但他们是不负责生殖发育。特定阶段的严重GA缺乏的表型的ga 3 ox 1/ga 3 ox 2突变体表明，AtGA 3 ox 3和AtGA 3 ox 4是严格调节的发展线索，AtGA 3 ox 3和AtGA 3 ox 4不上调，以弥补GA缺乏营养生长的双突变体。
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.