Comparative Regulation of Genes Involved in Plant Disease Resistance and Pigment Biosynthesis

在植物中，特定的分支途径不同于中央苯丙烷途径，该途径导致木质素、紫外线吸收类黄酮以及异黄酮类和香豆素抗生素的合成。环境胁迫，如紫外线和病原体，通过特定的分支诱导保护化合物的选择性合成。虽然中央通路中基因调控的协调变化已被证明是这些生理反应的基础，但控制分支通路差异激活的机制尚不清楚。作为理解这些途径中调节合成的协调和选择性控制的模型，本研究侧重于黄酮类和异黄酮类抗生素合成的中央和分支途径中编码酶的基因的比较调节。查尔酮异构酶是一种可能的调节酶，将作为中枢途径的代表进行研究。这项研究将确定调控查尔酮异构酶和分支途径P-450基因表达的DNA序列。这将通过以下方式完成：识别分支通路P-450基因，并表征它们在环境诱导物和发育过程中的表达；将转录单位定位在基因组克隆上；通过构建嵌合基因来定位调节区；并对功能重要区域进行测序。%预计这项研究将揭示不同的启动子元件对特定的环境或发展信号。这项对苯丙烷途径基因中这些元件的组织的研究可能会导致植物代谢相关基因的差异调控的一般模型。此外，如果要通过基因操作来增强植物的抗病能力，对植物抗病蛋白生物合成的遗传调控的基本了解是至关重要的。

In plants, specific branch pathways diverge from the central phenylpropanoid pathway which leads to the synthesis of lignins, UV-absorbing flavonoids, as well as isoflavonoid and coumarin antibiotics. Environmental stresses such as UV light and pathogens induce the selective synthesis of protective compounds by particular branches. While coordinate changes in gene regulation in the central pathway have been demonstrated to underlie these physiological responses, the mechanisms controlling differential activation of branch pathways is unknown. As a model for understanding the coordinate and selective controls regulating synthesis within these pathways, this research focuses on the comparative regulation of genes encoding enzymes in the central and branch pathways for synthesis of flavonoids and isoflavonoid antibiotics. Chalcone isomerase, a possible regulatory enzyme, will be studied as a representative of the central pathway. The research will identify the DNA sequences regulating the expression of the chalcone isomerase and branch pathway P-450 genes. This will be accomplished by: identifying branch pathway P-450 genes and characterizing their expression in response to environmental inducers as well as during development; mapping the transcription units on genomic clones; localizing regulatory regions by construction of chimeric genes; and sequencing the functionally important regions.%%% It is expected that this research will reveal distinct promoter elements responsive to particular environmental or developmental signals. This study of the organization of these elements in the phenylpropanoid pathway genes may lead to a general model for differential regulation of metabolically related genes in plants. Furthermore, a fundamental understanding of the genetic regulation of phytoalexin biosynthesis is essential if this trait is to be genetically manipulated to enhance disease resistance in plants.***//