Hormonal Regulation of Gene Expression in Cereal Aleurone Layers

[408900]植物激素赤霉素（giberellin， GA）在种子萌发和萌发后生长、茎伸长和花诱导等几个重要的生理和发育过程中发挥调控作用。已知赤霉素和另一种激素脱落酸（ABA）调节几种酶的合成和分泌，这些酶负责利用谷物中储存的营养物质。这些酶中最丰富的是淀粉降解α -淀粉酶和储存蛋白降解蛋白酶。随着对这两种植物激素作用方式的长期研究的继续，在萌发大麦种子糊粉层中，将研究激素对α -淀粉酶和蛋白酶基因协调表达的影响。具体来说，我们计划：1)分析蛋白酶启动子中负责激素调节的顺式作用元件，2)研究GA和ABA如何调节这种DNA结合蛋白的水平/活性，3)分离和表征“早期”GA诱导基因的cDNA克隆，这些基因的表达被认为对后期α -淀粉酶和蛋白酶的表达很重要。希望本项目所获得的信息将有助于我们了解这些激素在植物基因调控中的分子作用。＊＊＊

9408900 Ho The plant hormone, gibberellin (GA), exerts regulatory roles in several important physiological and developmental processes such as seed germination and post-germination growth, stem elongation and flower induction. Gibberellin and another hormone, abscisic acid (ABA), are known to regulate the synthesis and secretion of several enzymes which are responsible for the utilization of nutrients stored in cereal grains. The most abundant among these enzymes are the starch-degrading alpha-amylases and the storage protein- degrading proteinases. As the continuation of long term effort in elucidating the mode of action of these two plant hormones, the effect of hormones on the coordinated expression of alpha-amylase and protease genes will be studied in the aleurone layers of germinating barley seeds. Specifically it is planned to: 1) analyze the cis-acting elements in the protease promoter that are responsible for hormonal regulation, 2) investigate how GA and ABA regulate the level/activity of this DNA binding protein, and 3) isolate and characterize cDNA clones for "early" GA-induced genes whose expression has been suggested to be important for later alpha-amylase and proteinase expression. It is hoped that the information obtained in this proposed project will contribute to our understanding of the molecular action of these hormones on gene regulation in plants. ***