核盘菌是一种重要的植物病原真菌，其引起的菌核病是我国油菜、大豆和向日葵等多种作物上的首要病害。真菌病毒可以引起植物病原真菌致病力衰退，被认为是很有前景的生物防治材料,但是由于人们对其传播和流行等基本生物学特性认识的缺乏，目前利用真菌病毒防治植物病害的策略是利用携带病毒的弱毒菌株传播病毒，由于传播效率低和带毒菌株生态适应性差等原因仅有一例成功。我们前期研究发现核盘菌低毒力相关DNA病毒1（SsHADV-1）具有显著的体外侵染特性，在培养基和植物叶片上均可以感染核盘菌，有很好的生物防治菌核病的潜能。本项目将重点研究该病毒的生存适应性、体外侵染能力以及传播途径等基本生物学特点，明确该病毒对农作物的安全性和生物防治的有效性，从而评估将SsHADV-1研制成为新型病毒杀真菌剂的可行性。本研究结果将扩展人们对真菌DNA病毒基本特征的认识，为利用低毒相关病毒控制作物病害提供理依据。

Sclerotinia sclerotiorum is a notorious plant fungal pathogen which causes great damages to economically important crops including rapeseed, soybean and sunflower in China.Mycovirus was considered to be an important biocontrol agent becasouse part of them can induce hypovirulence of plant fugal pathogen. The knowledge about the biology and ecology of mycoviruses is still very limited. Generally, mycoviruses are considered to lack extracellular infectivity, so the biocontrol of plant disease with mycovirus is mainly through the intracellular transmission, however, there is only one successful example because of the low transmission ratio and the fitness of hypovirulence strains. In the previous study, we discovered that purified viral particles of Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1), are infectious when applied extracellularly to its fungal host S.sclerotiorum, which is strikingly different from the previous mycovirus. Indoor experiments demonstrated the outstanding biocontrol potential of SsHADV-1 towards the diseade caused by S. sclerotiorum. Thus, our proposal here will focus on the study of biological characteristics of SsHADV-1 in the field such as the adaptability, extracellular infectivity and tansmission ability. The biocontrol effection and enviromental security of crops in the field will aslo be evaluated.Though these researches we could confirm the feasibility that the application of SsHADV-1 particles as a novel viral fungicide. The results of this study will expand the knowledge of the DNA mycovirus and provide a theoretical basis for the use of hypovirulence-associated mycovirus in biocontrol of plant disease.