Comparative genomics of model plant and non-model plants based on metabolome analysis

本研究以模式植物为研究对象，以药用植物和作物为研究对象，采用比较遗传学方法，对植物基因表达和代谢网络进行了研究。以次级代谢产物差异的化学型、转基因突变体或培养组织为实验材料，对与次级代谢调控机制相关的基因进行了分析。(1)花色素苷的产生和积累：分析了过表达PAP 1的拟南芥中特异诱导的基因，并获得了功能未知的基因。通过对这些基因敲除株的代谢组学分析，鉴定了一种新的BAHD酰基转移酶的功能。通过比较紫苏和PAP1拟南芥中表达的GST同源物，阐明了二者在种皮形成中的功能差异。(2)喜树碱的产生：从矮蛇根草的毛状根中分析了喜树碱生物合成途径的候选基因。分析了RNAi毛状根中的代谢组学变化，并预测了基因功能。对喜树碱作用的靶蛋白拓扑异构酶I的氨基酸序列进行了比较。在喜树碱产生植物中发现了引起对喜树碱的自身抗性的氨基酸替换。(3)喹诺里西啶生物碱（羽扇豆生物碱）：使用含生物碱的“苦味形式”和不含生物碱的“甜味形式”的狭叶羽扇豆，分析“苦味特异性”基因。利用重组蛋白在E.大肠杆菌中，进行脱羧酶的酶表征。对该酶的氨基酸序列进行了比较，发现了几种常见的取代。

In this study, the networks of gene expression and metabolism in plant were investigated by the comparative genetics between a model plant, and medicinal and/or crop plants. The chemotypes, transgenic mutants or cultured tissues that differ in secondary metabolites, were used as the experimental materials to profile genes concerning on the control mechanism of secondary metabolisms. (1) Anthocyanin production and accumulation: The specifically induced genes in PAP1-over-expressing arabidopsis were profiled and function unknown genes were obtained. By metabolome analysis of knockout lines of these genes, the function of a new BAHD acyltransferase was identified. From the comparison between GST homolgues expressed in pigmented perilla and PAP1 arabidopsis, functional difference in seed coat pimentation was clarified. (2) Camptothecin production: The candidate genes for the biosynthesitic pathway of camptothecin were profiled from the hairy roots of Ophiorrhiza pumila. The metabolome changes in RNAi hairy roots were analyzed and gene functions were predicted. The amino acid sequences of Topoisomerase I, the target protein of camptothecin, were compared among of several plants and human. The amino acid substitutions which cause the self-resistance against camptothecin were found in camptothecin-producing plants. (3) Quinolizidine alkaloid (Lupin alkaloid): Using alkaloid-containing 'Bitter form' and alkaloid-free 'Sweet form' of Lupinus angustifolius, 'bitter-specific' genes were profiled. Using the recombinant protein expressed in E. coli , enzymatic characterization of a decarboxylase was performed. Comparison of amino acid sequences of this enzyme among quinolizidine alkaloid containing species, several common substitution were found.