Gibberellin Biosynthesis in Maize-Chemistry, Biochemistry and Genetics

WPC 2 B P Z Courier 10cpi #| x =V x 6 x @ 8；X @佳能LBP-8III（附加）calb8ad。PRS x @ 0jzx @ #| x % bxg F ' Courier 10cpi快递员脚注16cpi？ x x x, =V x 6 x @ 8；X @ + h h h, s, h 6 X @；通过开创性地使用单基因突变体，PI已经确定了赤霉素途径的大部分步骤。玉米营养芽的生物合成。我们已经证明，GA - 1是控制玉米茎伸长的主要赤霉素，而geranylgeranylpyrophosphate （GGPP）被代谢为？x共聚焦磷酸（CPP0, ent kaurene， GA 12和g1）通过早期13羟基化分支途径。该提案描述了代谢实验，将在该分支途径中建立剩余的五个步骤，并定位d2， d3和anl突变体阻断的步骤。此外，对a ？“GA 12的第二个分支通路（早期非3,13羟基化通路）将评估该通路在控制玉米GA依赖性生长中的重要性。”所提出的代谢研究的结果将为玉米芽的赤霉素生物合成途径提供详细的描述，并将为其他植物的研究提供模型。寻找更多的GA（矮）突变体将继续进行：这些突变体是通过使用玉米转座因子Ac的转座子标记产生的。新突变体的遗传块的位置将通过生物测定、内源性给草素的定性分析和代谢研究来确定。这一提议的一个令人兴奋和新颖的方面来自转座子标记矮突变体的可用性。该方法为特异基因的克隆提供了一种简便的方法。这些克隆将与传统方法结合使用，分离控制生物合成途径中特定步骤的酶。本研究的目的是了解赤霉素（giberellins, GAs）类植物激素对茎伸长的控制。我们的策略是：(i)识别通路中这些步骤的基因和基因产物，（iii）分析控制这些步骤的酶，从而为未来操纵植物生长提供信息。＊＊＊

WPC 2 B P Z Courier 10cpi #| x =V x 6 X @ 8 ; X @ Canon LBP-8III (Additional) CALB8IAD.PRS x @ 0J zX @ #| x 2 % B X g F ` Courier 10cpi Courier Footnote 16cpi . ? x x x , =V x 6 X @ 8 ; X @ + H H H , S , H 6 X @ ; @ t 7 } 3 J4 s @ u $ u $ t 7 } 3 O4 K ^_ZY X P C~ } X C~ YX P C~ X PSQRVW 8 W u a c e g i i = : W _^ZY X 9306597 ` ` Phinney Through the pioneering use of single gene mutants, the PI has defined most of the steps in the pathway for gibberellins ? biosynthesis in maize vegetative shoots. We have shown that GA 1 is the major gibberellin controlling stem elongation in maize and that geranylgeranylpyrophosphate (GGPP) is metabolized to ? x copalylpyrophosphate (CPP0, ent kaurene, GA 12 , and G 1 via the early 13 hydroxylation branch pathway. This proposal describes metabolic experiments that will establish five remaining steps in this branch pathway and locate the steps blocked by our d2 , d3 , and anl mutants. In addition, metabolic studies with five members of a ? ` second branch pathway from GA 12 (the early non 3,13 hydroxylation pathway) will assess the importance of this pathway in the control of GA dependent growth in maize. The results from the proposed metabolic studies will provide a detailed description of the gibberellin biosynthetic pathways for maize shoots and will provide a model for studies with other plants. A search for additional GA (dwarf) mutants will be continued: these mutants are being generated by transposon tagging using the maize transposable element Ac. The location of the genetic blocks for the new mutants will be determined form bioassays, qualitative analysis of endogenous givverellins, and metabolic studies. An exciting and novel aspect of this proposal comes from the availability of transposon tagged dwarf mutants. The approach provides a convenient method for cloning specific genes for GA biosynthesis. These clones will be used in conjunction with conventional methods to isolate the enzymes that control specific steps in the biosynthetic pathway. %%% The objective of the research is to understand shoot elongation controlled by the class of plant hormones, the gibberellins (GAs). The strategy is to (i) identify the genes and the gene products for these steps in the pathway, and (iii) analyze the enzymes controlling these steps, and thereby provide information for the future manipulation of plant growth. ***