真菌毒素Acetoxydehydroaustin A 的生物合成机制及其类似物杀虫活性评价

Two species, Verticillium dahlia and V. lecanii, from the genus Verticillium have been known to be able to produce mycotoxins, but until now mycotoxins have not yet been reported in V. albo-atrum that was considered as a major pathogenic fungi of cotton cyanosis. In the previous study, we have isolated a novel meroterpenoids mycotoxin with a unique insecticidal mechanism, named as Acetoxydehydroaustin A, from the phytopathogenic fungus V. albo-atrum. In this project, we will explore the action mechanism of the enzymes related to aldol-condening reaction during the biosynthesis of Acetoxydehydroaustin A through investigating the pathways of biosynthesis and identifying the biosynthetic gene cluster of the new mycotoxin Acetoxydehydroaustin A. It was expected that a large numbers of the analogues of mycotoxins Acetoxydehydroaustin A will be obtained based on heterelogous expression strategy. To discover novel skeleton of insecticides, we will examine the insecticidal activity of these mycotoxin analogues of Acetoxydehydroaustin A that was isolated and identified in the process of biosynthesis. In addition, it is further evaluated whether some key pesticide lead structures could be screened from these mycotoxin analogues. It will be great realistic and strategic significance for creating new pesticides with independent intellectual property rights in China.

轮枝菌属的大丽轮枝菌Verticillium dahliae和蜡蚧轮枝菌V. lecanii真菌均可产生毒素，但作为棉花黄萎病主要病原菌之一的黑白轮枝菌(V. albo-atrum)中尚未见毒素报道。在前期的研究中，申请者已从黑白轮枝菌(V. albo-atrum)中发现一个新的具有独特杀虫机制的混源萜类真菌毒素Acetoxydehydroaustin A。本项目通过研究真菌毒素Acetoxydehydroaustin A的生物合成途经，寻找PKS基因中各功能基因，明确其生物合过程中缩醛反应的相关酶的作用机理，在异源表达的基础上获得更多真菌毒素Acetoxydehydroaustin A的类似物，并对这些化合物进行杀虫活性测试，评价其作为杀虫剂先导结构的可能性，争取发现作用机制独特、结构新颖的新型杀虫剂的源头分子，对创制具有我国自主知识产权的新型杀虫剂具有重大的现实和战略意义。

本项目通过研究真菌毒素Acetoxydehydroaustin A 的生物合成途经的初步探讨，初步确定了其生物合成及基因合成簇PKS各功能基因，克隆了大丽轮枝菌(V.albo-atrum)的具有杀虫活性的真菌毒素Acetoxydehydroaustin A 的生物合成相关基，并建立起了以构巣曲霉为底盘的异源表达系统，进行适当的基因改造，并成功构建了20多个转化子；同时我们也完成了真菌Talaromyces marneffei中列新型chrodrimanins杀虫混源萜类化合物的生物合成骨架的生物合成途径构建，为后期卤代混源萜的生物合成及卤化机制的研究奠定基础。在此基础上并发现了25个结构新颖的化合物。并对这些化合物进行杀虫活性的筛选和评价，现了5个值得进一步研究的杀虫化合物，对创制具有我国自主知识产权的新型杀虫剂具有重大的现实和战略意义。