Biochemical Genetics and Gibberellin Biosynthesis in Maize

本研究分析了赤霉素(GA)的生物合成与玉米地上部生长的关系。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)和遗传学(分子和生理学)的学科。本研究的具体目标是利用GA突变体(和正常系)：(1)分析愈伤组织培养中的基因表达；(2)鉴定玉米GA接合子并分析幼苗的接合；(3)GA1水平与D_1突变体幼苗的短、中等位基因之间的关联；(4)定位被d2、d3和an1突变体阻断的GA生物合成途径中的步骤：(5)用标记的GA4、GA7和2，3-脱氢-GA9研究玉米幼苗中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酶的性质；(7)继续矮秆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学研究。GAs是一种植物激素，调节许多植物的反应，包括枝条的伸长。在玉米中，缺乏内源GA1的植株具有矮小的生长习性。5个矮秆突变体(GA突变体)被用来揭示GA生物合成途径的细节，并确定特定的GA在控制依赖GA的芽伸长中的作用。

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.