Biochemical Genetics and Gibberellin Biosynthesis in Maize

本研究分析了赤霉素（GA）的生物合成与玉米茎部生长的关系。该方法结合了化学（有机合成）、生物化学（放射性标记饲料和酶学）和遗传学（分子和生理学）等学科。本研究的具体目标是利用基因突变体（和正常基因）：(1)分析愈伤组织培养中的基因表达；(2)鉴定玉米GA偶联物并分析其在幼苗中的偶联性；(3) GA1水平与d1突变苗短等位基因和中间等位基因的相关性；(4)定位d2、d3和an1突变体阻断的GA生物合成途径的步骤；(5)通过标记GA4、GA7和2,3-脱氢ga9的饲养研究，分析玉米芽中GA3的生物合成来源；(6)研究控制GA20到GA1步骤的正常和突变羟基化酶的性质；(7)继续开展矮化基因克隆的初步研究；(8)继续对与GA代谢有关的玉米突变体进行经典遗传研究。气体是植物激素，调节许多植物反应，包括茎伸长。在玉米中，缺乏内源GA1的植株具有矮秆生长习性。五个矮突变体（GA突变体）揭示了GA生物合成途径的细节，并确定了特定的GAs在控制GA依赖的茎伸长中的作用。

This research analyzes gibberellin (GA) biosynthesis in relation to shoot growth in maize. The approach combines the disciplines of chemistry (organic synthesis), biochemistry (radiolabelled feeds and enzymology) and genetics (molecular and physiological). The specific goals of this research are to use GA mutants (and normals): (1) to analyze gene expression in callus tissue cultures; (2) to identify maize GA conjugates and analyze conjugation in seedlings; (3) to correlate levels of GA1 with the short and intermediate alleles of d1 mutant seedlings; (4) to locate the steps in the GA biosynthetic pathway blocked by the d2, d3 and an1 mutants; (5) to analyze the biosynthetic origin of GA3 in maize shoots from feeding studies with labelled GA4, GA7 and 2,3-dehydro-GA9; (6) to study the properties of normal and mutant hydroxylase, the enzyme controlling the step GA20 to GA1; (7) to continue preliminary studies on cloning the dwarfing genes; and (8) to continue classical genetic studies with mutants of maize concerned with GA metabolism. GAs are plant hormones that regulate many plant responses including shoot elongation. In maize, plants lacking endogenous GA1 possess a dwarf habit of growth. Five dwarf mutants (GA mutants) are used to unravel details of the GA biosynthetic pathway, and to define the role of specific GAs in the control of GA dependent shoot elongation.