前期研究发现感染低毒相关DNA病毒（SsHADV-1）的核盘菌低毒菌株可在油菜上进行内生性生长，用其处理油菜可显著提高油菜籽含油量，最高可提高3.75 %。针对这一特性，本项目拟研究低毒菌株在油菜体内的分布和生活史，研究低毒菌株内生性生长对油菜生长、发育和抗逆及对SsHADV-1传播的影响；利用RNA-Seq、基因超量表达和基因沉默等技术及KEGG PATHWAY数据库等，研究核盘菌从死体营养型病原菌转变为油菜内生真菌后关键信号通路和代谢通路的变化以及油菜应答核盘菌内生性生长的分子机制，研究核盘菌内生性生长对油菜脂肪代谢通路及关键基因表达的影响以之解析刺激油菜籽含油量提高的分子机制。项目的完成将对解析病原真菌转变为内生真菌的机制有显著促进作用；将建立“真菌病毒－病原真菌－寄主”交互作用模式，丰富真菌病毒学理论和实践；也将为创建一种显著提高油菜生产效益的新型防病、增油生物菌剂提供理论依据。

Previously, we reported Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1) has a potential to control stem rot of rapeseed (Brassica napus) caused by Sclerotinia sclerotiorum. Recently, we found that the SsHADV-1-mediated hypovirulent strain could grow endophytically in rapeseed, and this hypovirulent strain could increase seed oil content by up to 3.75 % when plants were treated with hypovirulent strain. Our finding showed that S. sclerotiorum is converted to an endophyte from a typical necrotrophic pathogen, and the endophytic growth is likely to give strong impact on its host. Based on the endophytic property of the hypovirulent strain of S. sclerotiorum, we propose to study the endophytism of SsHADV-1-mediated hypovirulent strain of S. sclerotiorum and molecular interaction with rapeseed, and four aspects listed below will be considered.① Probing if there is any possible mutualistic symbiosis among mycovirus, fungal and rapeseed. The distribution and life cycle of the endophyte growing in rapeseed will be studied, and its impact on the growth, development and stress-resistance of rapeseed and on the transmission of mycovirus will be examined. ② Unravelling the endophytism of S. sclerotiorum. The key signal transduction pathways and metabolism pathways of endophytic growth which are significantly different from those pathways of necrotrophic growth and saprobiotic growth will be identified, and the genes whose expressions are significantly regulated will be analyzed functionally. ③ Understanding the response of rapeseed to the endophytic growth of S. sclerotiorum. The key metabolism pathways and signal transduction pathways of rapeseed which are significantly different from S. sclerotiorum-free plants will be studied, and the metabolites and secondary metabolites responding to those changed pathways will be detected and key genes whose expressions are significantly regulated will be also founctionally analysed. ④Understanding the mechanism for promoting seed oil content by endophytic growth of S. sclerotiorum. The lipids metabolism pathways and the key genes which are regulated by the endophytic growth of S. sclerotiorum will also be studied during bloom stage of rapeseed. Hopefully, our study will shed light up on the endophytism of a typical necrotrophic pathogen which may help us to understand the potential contribution of endophytic growth of fungal pathogens on the development and prevalence of crop diseases; our study may also be used to establish a model for triple interaction among mycovirus, fungal pathogen and plant host which may improve our knowledge on mycovirus transmission and help us to explore hypovirulence-associated mycoviruses as biological control agents; finally, our study also will help us to develop a biological agent to control stem rot of rapeseed and enhance seed oil content simultaneously which may be used to impove the productivity effect of rapeseed in China.