28 トマト由来のブラシノステロイド生合成・代謝に関わるチトクロムP450のクローニングと機能解析

概要

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Cytochromes P450 are membrane-bound heme proteins catalyzing the monooxygenation of lipophilic substances. Recently several P450 genes have been isolated in the course of cloning of the genes from the mutants deficient in brassinosteroid (BR) (Arabidopsis cpd, dwf4, bas1, and tomato dwarf) and gibberellin (GA) (Arabidopsis ga3, and maize dwafr3). Interestingly, most of the P450s so far isolated from these mutants belong to 85 clan in phylogenetic tree of plant P450s. Recently Arabidopsis BAS1 (CYP72B1) has been isolated and suggested to catalyze the C26-hydroxylation of brassinolide. In this study, to investigate regulation of BR biosynthesis and metabolism in tomato, we have obtained several P450 cDNAs belonging to 85 clan and CYP72 family from tomato. The tomato cDNA, to90AH, showed 74% identity to CPD, suggesting that to90AH catalyzes the C23-hydroxylation. The other tomato clone, to72BH showed 60% identity to BAS1 and 35〜45% to CHIBI2 and CYP72A. Thus to 72BH may catalyze the C25 or C26 hydroxylation of BR to inacrivate BR. molecules. Functional analysis of these P450s by expression in heterologous cells and in Arabidopsis is in progress.
植物化学調節学会の論文
2000-11-02