低毒病毒及板栗疫病菌低毒力机制

低毒病毒是一类存在于板栗疫病菌细胞质中自主复制的无衣壳正链RNA病毒。感染低毒病毒后，板栗疫病菌的致病力显著降低，色素分泌减少，菌丝体由感染病毒前的桔黄色变为白色，产孢量降低或不产孢，漆酶表达水平明显下降。低毒病毒侵染性克隆的获得以及高效转化和转染体系的建立，使得低毒病毒成为目前唯一可以进行全面遗传操作的真菌病毒。利用低毒病毒作为探针来探测板栗疫病菌的致病力组成和毒力调节机制，己获得了一些很有意义的发现。本文介绍近几年低毒病毒及其与真菌相互作用的研究进展，包括低毒病毒的基因组和功能基因研究、低毒病毒和线粒体损害引起的板栗疫病菌低毒力机制、板栗疫病菌的RNA沉默系统以及低毒病毒抗RNA沉默的机制。低毒病毒／板栗疫病菌系统已经成为研究病毒与宿主相互作用以及病原真菌致病机理的很好的模式系统。

Hypoviruses and Mechanisms of Hypovirulence in Cryphonectria paras itica

Hypoviruses are a group of unencapsidated, cytoplsmically self-replicating plus sense RNA viruses found in the chestnut blight fungus Cryphonectria parasitica. Hypovirus infection results in persistent changes in multiple traits of the fungal host that include reduced pathogenicity, modification of colony pigmentation, suppressed asexual spore production, loss of female fertility and reduction of laccase. The development of infectious hypovirus eDNA clones and transformation/transfection systems make the hypovirus to be currently the only virus which can be manipulated genetically in the whole kingdom of fungi. Using hypoviruses as probes, many interesting insights of pathogenecity and regulation of virulence in C. parasitica have been uncovered. In this article, we review the recent development in hypovirus and the interaction between the virus and the host fungus, including the genome structure and the functions of viral gene products, mechanisms of hypovirulence resulted from the hypovirus infection and malfunction of the mitochondrion, the RNA silencing of the fungus and the counter silencing mechanisms by the hypovirus. The hypovirus/C, parasitica system has evolved into a very useful model for understanding the interaction between a virus and its host and for dissecting the virulence regulation o f a pathogenic fungus.