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

本研究通过模式植物与药用植物和/或农作物的比较遗传学研究了植物基因表达和代谢网络。以次生代谢物不同的化学类型、转基因突变体或培养组织为实验材料，对次生代谢物调控机制相关基因进行了研究。(1)花青素的产生和积累：对PAP1高表达拟南芥中的特异诱导基因进行了分析，获得了功能未知的基因。通过对这些基因敲除系的代谢组学分析，鉴定了一个新的BAHD酰基转移酶的功能。通过比较色素紫苏和拟南芥PAP1中表达的GST同源基因，阐明了种皮受精过程中的功能差异。(2)喜树碱合成：从麦冬毛状根中筛选出喜树碱生物合成途径的候选基因。分析了RNAi毛状根的代谢组变化，并对基因功能进行了预测。比较了几种植物和人的喜树碱靶蛋白拓扑异构酶I的氨基酸序列。在喜树碱生产植物中发现了导致自身对喜树碱产生抗性的氨基酸替换。(3)奎诺利定生物碱(羽扇豆碱)：利用小叶羽扇豆含生物碱的“苦型”和不含生物碱的“甜型”，对其“苦型”基因进行了分析。利用在大肠杆菌中表达的重组蛋白，对脱羧酶进行了酶学性质研究。对该酶的氨基酸序列进行了比较，发现了几种常见的喹诺利定生物碱替代。

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.