Septin基因调控菟丝子生防菌“鲁保一号”致病力退化的分子机制

Colletotrichum acutatum strain “LuBao No.1” (LB1) showed high herbicidal activity to Cuscuta chinensis. However, the “LB1” strain is prone to degradation in pathogenicity after continuous sub-culturing, and which directly affect the production and application of this biocontrol agent. It is believed that the Septin gene plays an important role in the pathogenicity degradation of LB1 strain combined with screened of the T-DNA inserted mutant library and RNA-Seq analysis. The purpose of this project is to clarify the mechanism of the pathogenicity degradation and to obtain a pathogenic stably strain of LB1 by the means of functional gene analysis at the bases of previous research. Moreover, we do systematically research on gene functions of Septin2 and Septin5 and their interaction network by homologous recombination, histidine pull-down, proteomics and other techniques, to clarify the mechanism of the pathogenicity degradation of the LB1 strain. Meantime, it may provide theoretical basis for the study of the pathogenicity degradation of other fungi.

利用“鲁保一号”菌防除菟丝子（Cuscuta chinensis）效果显著，但是该菌在连续继代培养后极易发生致病力的退化，这也直接影响到“鲁保一号”菌剂的生产和应用效果。我们前期通过筛选“鲁保一号”菌株T-DNA插入突变体库，并结合菌株致病力退化前后差异转录组（RNA-Seq）分析，认为Septin基因在该菌株致病力退化过程中起重要作用。本项目以前期研究结果为基础，以功能基因及调控网络研究为主要手段，通过同源重组、组氨酸pull-down和蛋白质组学等技术，系统研究Septin2和Septin5基因在“鲁保一号”菌株致病力退化过程中的作用和调控网络，阐明“鲁保一号”菌株致病力退化机制，得到致病力稳定的改良型“鲁保一号”菌株，同时也为其它真菌致病力退化机制的研究提供理论依据。

菟丝子是一类在我国广泛分布的恶性寄生杂草。“鲁保一号”是一个对菟丝子具有良好防效的生物菌剂。本研究克隆了“鲁保一号”菌28S rRNA和甘油醛三磷酸脱氢酶（GAPDH）基因，并进行了进化分析。研究了其侵染部位与方式。筛选获得致病力稳定T-DNA插入突变菌株Tlb128，并克隆了其关键调控基因。开展了突变体关键性状的转录组和蛋白质组的交叉关联分析。结果显示，“鲁保一号”菌为尖孢炭疽菌菟丝子专化型，能够通过菟丝子茎和“吸器”部位完成侵入，并形成深褐色病癍。克隆了Septin类致病力稳定调控基因KN1。通过多组学分析构建了基于KN1基因为关键点的调控路径，KN1基因的突变能够引起126个基因的表达发生变化，筛选致病力调控相关基因，对于完善“鲁保一号”菌株生防机制有重要作用。