Studies On The Biological Characteristics And Mycovirues Of Botrytis Cinerea HBstr-470

The host range of Botrytis spp.is wide,which includes over 1400 plant species,causing dramatic economic loss.In this study,we investigated the biological characteristics of B.cinerea strain HBstr-470,the molecular characteristics of viruses in strain HBstr-470 and determined the viral transmission ability and the effects of viral infection on the biology of B.cinerea.Moreover,we also screened and analyzed the differentially expressed genes in the conidiation progress of strain HBstr-470 through RNA-seq.B.cinerea strain HBstr-470 showed low mycelial growth rate and abnormal colony morphology,and produced lots of aerial hyphae and abundant conidia on PDA plate.The conidia producted by strain HBstr-470 germinated regularly with the germination rate of over 90%.The production of conidia on single-conidium colonies was much sooner than virulent strain B05.10 and stable,and also was independent of light.However,the virulence of strain HBstr-470 on Nicotiana benthamiana was significantly impaired compared with strain B05.10.B.cinerea strain HBstr-470 was co-infected by five mycoviruses,including Sclerotinia sclerotiorum hypovirus 2/HBstr-470(SsHV2/HBstr-470),Botrytis cinerea hypovirus 1/HBstr-470(BcHV1/HBstr-470),Botrytis cinerea victorivirus 1/HBstr-470(BcVV1/HBstr-470),Botrytis cinerea RNA 2/HBstr-470(BcRV2/HBstr-470)and Botrytis cinerea partitivirus 2/HBstr-470(BcPV2/HBstr-470).SsHV2/HBstr-470 and BcHV1/HBstr-470 were clusted into the family Hypoviridae.BcVV1/HBstr-470 was most closely related to members of the genus Victorivirus in the family Totiviridae.BcRV2/HBstr-470,lacking the corresponding segment encoded CP in RnQV1/W1075,was the most closely related to RnQV1/W1075.It was supposed that BcRV2/HBstr-470 might be a novel member in Quadriviradae.BcPV2/HBstr-470 was clustered into the family of Partitiviridae with other members in the family.In addition,mycoviruses from strain HBstr-470 can be stably vertical transmissed to conidia.According to the analysis between viral infection and the biological characteristics of derivative isolates obtained through horizontal transmission for different donor strains,we found that SsHV2/HBstr-470 and BcVV1/HBstr-470 positively regulate conidiation of B.cinerea;BcHV1/HBstr-470 was probably related to the hypovirulence;BcRV2/HBstr-470 had an influence on low mycelial growth,reducing virulence and high sporulation rates;and BcPV2/HBstr-470 was associated with reduced pathogenicity and increased production of conidia.A total of 368 differentially expressed genes in the conidiation progress of strain HBstr-470 were enriched in oxidation-reduction process,oxidoreductase activity process,heme binding process and tetrapyrrole binding process,it was susposed that DEGs in oxidation-reduction process were invoved in conidiation progress.DEGs were enriched in ribosome and amino sugar and nucleotide sugar metabolisms pathway in the KEGG pathway analysis.Moreover,the specific DEGs of strain HBstr-470 are involved in transmission of mycoviruses,viral transcription and plasma membrane fusion,which is probably associated with the vertical transmission of the mycoviruses in strain HBstr-470 from hyphae to conidia.