| Botrytis spp.is a common fungal group in nature with very wide host range,causing gray mold on many economically important corps.Among them,Botrytis cinerea has the widest distribution and the greatest harm,which form symptom of gray-white or graybrown mold at the infected part,resulting in devastating diseases and great economic losses.Mycoviruses can infect a variety of fungi including Botrytis,while some of them can weaken the pathogenicity of host fungi with the potential of biological control.A mycovirus,namely Botrytis cinerea hypovirus 1(BcHV1),carried by a hypovirulent Botrytis cinerea strain HBtom-372,was used in this study.The infectious clone system of BcHV1 was constructed,and its RNA was synthesized in vitro and then transfected into protoplasts of Botrytis cinerea strain B05.10 by PEG.BcHV1 can be detected by using RT-PCR,dsRNA electrophoresis and Northern blot in strains B05.10-13 V and B05.10-14V carrying BcHV1,which establishes a technical system for studying the interaction between BcHV1 and Botrytis cinerea.The infectious clone of BcHV1 was used to introduce BcHV1 into different Botrytis cinerea strains,Botrytis cinerea related species and other fungi.The selected hosts include four Botrytis cinerea strains,namely ZC-7,ZC-8,WHG-5 and RCT-6;nine Botrytis cinerea related species,namely Botrytis porri,Botrytis sinoviticola,Botrytis tulipae,Botrytis pseudocinerea,Botrytis squamosa,Botrytis fabiopsis,Sclerotinia sclerotiorum,Sclerotinia nivalis,Monilinia fructicola;two distantly related fungi,namely Magnaporthe oryzae and Fusarium graminearum.However,BcHV1 was not successfully introduced into S.sclerotiorum,M.oryzae and F.graminearum.Among these infected strains,the biological phenotypes of B.cinerea strain RCT-6 and B.sinoviticola strain GBc-9 were affected.Compared with its original strain,the infected strains RCT-6-3V and RCT-6-4V showed slower mycelial growth and impaired pathogenicity.The infected strains GBc-9-3V and GBc-9-5V had sparse mycelium and its pathogenicity was almost lost.The accumulation of BcHV1 was detected by qRT-PCR in some selected strains and the highest accumulation was found in B.sinoviticola strains infected by BcHV1.Therefore,high accumulation of BcHV1 may be one reason responsible for the hypovirulence of strains GBc-9-3V and GBc-9-5V.This study find some new hosts for BcHV1 and also indicates that mycoviruses have different effects on different hosts and even on the different strains of the same fungal species.This may have great impact for further use of mycoviruses for biological control.The differentially expressed genes of the BcHV1-infected strain B05.10-14V at different stages were investigated by RNA-seq.The results showed that although BcHV1 infection did not affect the phenotype of strain B05.10,strain B05.10-14V still had 1750 DEGs in the vegetative growth stage,mainly enriched in the cytoplasmic membrane,transmembrane transport,oxidation-reduction and other processes,indicating that BcHV1 infection mainly affects the transmembrane transport process of the host.In addition,strain B05.10-14V had 273 DEGs in the pathogenesis stage,mainly enriched in transport and catabolism,RNA degradation and other processes,including vesiclular transport,endocytosis,autophagy and other processes.In the reported fungal antiviral genes,only Argonaute-like(agl2)was significantly up-regulated at the hyphal stage,indicating that it may play a role in the antiviral defense mechanism of the host. |
