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和/或作物植物的比较遗传学研究了植物基因表达和代谢网络。以次生代谢产物不同的化学型、转基因突变体或培养组织为实验材料，分析了次生代谢调控机制的相关基因。(1)花青素的产生和积累：分析了pap1过表达拟南芥的特异性诱导基因，获得了功能未知的基因。通过对这些基因敲除系的代谢组分析，确定了一种新的BAHD酰基转移酶的功能。通过比较色素紫苏和PAP1拟南芥中表达的GST同源物，阐明了种皮色素化的功能差异。(2)喜树碱的产生：从毛状根中分析喜树碱生物合成途径的候选基因。分析了RNAi毛状根代谢组的变化，并预测了基因功能。比较了喜树碱靶蛋白拓扑异构酶I在几种植物和人体内的氨基酸序列。在喜树碱产生植物中发现了引起喜树碱自抗性的氨基酸取代。(3)喹诺齐啶生物碱（罗苹生物碱）：利用含生物碱的“苦形态”和不含生物碱的“甜形态”的Lupinus angustifolius，分析了“苦特异性”基因。利用在大肠杆菌中表达的重组蛋白，进行了脱羧酶的酶学表征。将该酶的氨基酸序列与含喹诺齐啶类生物碱的物种进行比较，发现了几个常见的取代。

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.