Action of Le and Lip1 Genes in Controlling Stem Growth of Pisum by Gibberellins and Light

9318358 Sponsel拟议的研究将利用赤霉素（GA）生物合成突变体和豌豆（豌豆）的光生突变体来研究植物可以调节活性激素水平及其靶组织反应的机制。 在豌豆的le矮秆突变体中，完整植株中赤霉素A20通过3 β-羟基化转化为GA 1的转化减少。 GA 1是豌豆节间生长的活性GA。 最近报道的一些结果需要重新检查le突变的生化基础。 在体内和体外喂养标记的GA的研究将被用来检查是否LE突变干扰运输GA 20从叶（这是其推定的合成位点）的茎，或是否LE基因座可以编码的调节因子。 将使用气相色谱-质谱法对GA代谢物进行定性和定量分析，以提供明确的鉴别。 由于3 β-羟基化是GA生物合成中最重要的步骤之一，因此确定le突变的功能基础是必要的。 豌豆新特征的lip 1突变导致光不依赖的光形态建成。 在该突变体中，当豌豆幼苗从黑暗转移到光照（去黄化）时通常发生的茎生长的严重减少在完全黑暗中表现出来。 生化研究表明，光敏色素A的信号转导途径在突变体中受到影响。 将进行GA水平，代谢和组织响应性的这种突变的影响的调查，以确定GA生物化学的哪些方面是在photophogenesis的一个因素。 ***

9318358 Sponsel The proposed research will utilize gibberellin (GA) biosynthetic mutants and photomophogenetic mutants of Pisum sativum (garden pea) to investigate the mechanisms by which a plant can regulate both the levels of active hormone and the responsiveness of its target tissue. In the le dwarf mutant of pea the conversion of gibberellin A20 to GA1 by 3Beta-hydroxylation is reduced in intact plants. GA1 is the active GA for internode growth in pea. Some recently reported results necessitate a re-examination of the biochemical basis for the le mutation. In vivo and in vitro feeding studies of labeled GAs will be used to examine whether the le mutation interferes with the transport of GA20 from leaves (which are its putative site of synthesis) to stems, or whether the le locus could code for a regulatory factor. Qualitative and quantitative analyses of the GA metabolites will be conducted using gas chromatography-mass spectrometry providing definitive identification. Since 3Beta- hydroxylation is one of the most important steps in GA biosynthesis it is imperative that the functional basis of the le mutation is defined. The newly characterized lip1 mutation of pea results in light independent photomorphogenesis. In this mutant the severe reduction in stem growth which normally takes place when pea seedlings are transferred from dark to light (de-etiolation) is manifest in complete darkness. Biochemical studies suggest that the signal transduction pathway from phytochrome A is affected in the mutant. An investigation of the effect of this mutation of GA levels, metabolism and on tissue responsiveness will be conducted in order to define which aspects of GA biochemistry are a factor in photomophogenesis. ***