种仁印楝素形成积累的干旱胁迫诱导机制

Azadirachta indica (neem) is a kind of important resource plant that originated from the semiarid and arid tropics with great commercial potential in botanical pesticide. The azadirachtin content in neem seeds is about 0.3%～0.7%,which has shown prominent effects on controlling pests.Neem was introduced in China in 1986 for the first time and about 20,000 hm2 plantations were established in China now.. Developing environment-friendly biopesticide has been a new tendency around the world. The purpose of oriented culture of neem raw material forest is to increase the azadirachtins content and the yield of seeds. Based on the theory of secondary metabolism in this paper, neem clonal nursery stock will be used as experimental material to study azadirachtins content and their variations, and to interpret the relationship between azadirachtins accumulation of seeds and physiological and biochemical responses under drought stress conditions, and to reveal the mechanism of environmental induction of azadirachtins formation and accumulation in Azadirachta indica seeds in term of gene expression of key enzymes in secondary metabolic pathway,and to seek the theoretical bases of increasing azadirachtins content and the yield of seeds by the way of environmental regulation. The findings of this study are helpful to understand the anabolic theory of azadirachtins and have an important significance to further explore the oriented culture technology of special raw material forest aiming at cultivating botanical active substance.

印楝是原自热带干旱和半干旱地区的多用途树种，其种仁内含印楝素约0.3%～0.7%，对害虫防治效果显著，是植物源杀虫剂中最具商品化开发的资源植物。印楝于1986年首次引进到中国，目前全国推广种植约2万公顷。. 环境友好型生物农药的开发已成为世界农药发展的趋势。印楝生物农药原料林定向培育的技术核心是提高种仁印楝素的含量及其产量。本研究以植物次生代谢的基础理论为指导，以印楝无性系为研究材料，集中关键环境因子，重点研究干旱胁迫处理条件下果期种仁印楝素含量的变动规律，解读种仁印楝素含量与次生代谢各环节关键酶活性、及其基因表达之间的相关关系，深刻揭示种仁印楝素形成积累的环境诱导机制，探求通过环境调控途径提高种仁印楝素含量及其产量的理论依据。其研究结果不但可以增进对印楝素合成代谢基础理论的认识，还对以林源活性物质为培育目标的特种原料林定向培育技术体系的深入研究具有重要的参考应用价值。

印楝素是积累于印楝叶片和种仁中的次生代谢物质，已成为当今商品化开发最理想的植物源杀虫剂，提高原料林印楝素的产量和质量是印楝生物农药产业的核心。本项目以印楝素形成积累与环境诱导因子的关系为核心内容，主要通过干旱胁迫梯度设计控制试验，从嫁接繁殖模式的印楝无性系材料培育研究为起点，分别对营养生长阶段和生殖生长阶段的印楝，开展了从表型到相关代谢测定的系列研究，重点分析了不同水分条件对印楝生长、代谢及其印楝素含量的调控作用，揭示了印楝在初生代谢过程中碳水化合物、含氮化合物，以及次生代谢过程中相关萜类代谢酶活性的变化规律及其与印楝素含量的相关性，并由此提出了适度干旱胁迫可增加种仁印楝素含量的学术观点。项目采用Illumina测序技术，对生殖生长阶段的印楝无性系，开展了不同干旱胁迫条件下果实不同发育期的种仁转录组测序，筛选出了与印楝素次生代谢萜类合成密切相关的CMK、LUS基因，从终产物、蛋白质、核酸三个层面探索了印楝从接受环境信号到做出代谢调控的过程和分子机制。研究结果为进一步揭示印楝素的生物合成与转化机理提供理论依据，对提高印楝人工原料林定向培育技术的深入研究具有指导意义。截至目前，已发表研究论文9篇，其中SCI收录3篇，出版专著1部，获得国家授权发明专利1项，培养博士研究生2名。