Analysis Of Mycovirus Diversity Of Jujube Dry Rot Pathogen And Cloning Of Novel Virus Genome Sequences

Mycovirus refers to a type of virus that can replicate and multiply in fungi.Kinds of fungal viruses have been reported in many pathogenic fungi such as Sclerotinia sclerotiorum,Botrytis cinerea,Fusarium graminearum,Rhizoctonia solani,et al.The use of hypovirulence to control plant fungal diseases has become a new strategy.Therefore,screening and cloning mycovirus from pathogenic fungi have good potential and practical significance in the prevention and control of plant diseases.In this study,47 isolates of canker and dieback of jujube in China,Aplosporella javeedii NX55-3 and Fusarium oxysporum BH19 from different sources were used as materials,and high-throughput sequencing and virus sequence cloning techniques were used to detect the distribution of viruses in the tested strains.In combination with the in vitro inoculation test,the diversity analysis of mycovirus in the strains and their influence on the pathogenicity of host,perform sequence cloning on two novel mycovirus with well-located locations,obtain the full-length sequence of the virus,and classify and identify it It provides an important biological control resource for the use of mycovirus to control canker and dieback of jujube in China.The results were listed as follows:1.A total of 47 isolates of canker and dieback of jujube in China were collected from 5 regions of the laboratory.Based on the rDNA-ITS and EF1α,sequences data sets,the sequencing results showed that there were 5 species causing canker and dieback of jujube in China,which were Botryosphaeria dothidea、Spencermartinsia viticola、Diplodia seriata、Diplodia mutila 和 Phaeobotryon rhois.Through the determination of the pathogenicity of isolated branches,it was found that the pathogenicity of different species was different,and the pathogenicity of different strains of the same species was also different to some extent.The pathogenicity of B.dothidea was stronger than that of S.viticola.2.A total of 33 mycoviruses were identified which belong to 16 families and 3 unclassified families,23 genera and 2 unclassified genera by high-throughput sequencing.Of these mycoviruses,12 were double stranded RNA(dsRNA)viruses,20 were positive single stranded RNA(+ssRNA)viruses and only one was negative single stranded RNA(-ssRNA)genomes.Mitovirus was carried the highest rate.+ssRNA viruses were common and have diverse species,and-ssRNA virus was the least.There were differences in virus species among pathogenic isolates from different province,and there were also differences in virus species of different pathogen species.The most mycovirus species were detected in Gansu isolates,and the differences of fungal virus species in the isolates might be related to the evolution of strains and regions.3.Botryosphaeria dothidea tobamo-like virus(BDTLV)and Cyril virus(CV)were detected from B.dothidea isolates.We found that most strains have the two kinds of virus.Through semi-quantitative detection and strain pathogenicity detection,When the expression of viruses is high,the strains of pathogenic is reduced,speculated that the two expression of viruses affects the pathogenicity of strain.4.Aplosporella javeedii partitivirus 1(AjPV1)isolated from Aplosporella javeedii strain NX55-3.The AjPV1 genome contains two double-stranded RNA elements(dsRNA1 and dsRNA2).The size of dsRNA1 is 2,360 bp,and it encodes a putative RNA-dependent RNA polymerase(RdRp),while dsRNA2 is 2,301 bp in length and encodes a putative capsid protein(CP).AjPV1 is a new member of the family Partitiviridae that is related to members of the genus Betapartitivirus.5.Fusarium oxysporum alternavirus 1(FOAV1)isolated from Fusarium oxysporum strain BH19 which is genome is a dsRNA mycovirus.FOAV1 belongs to the proposed Alternaviridae family and Alternavirus genus,and its genome contains four genome segments with the length of 3447 bp,2677 bp,2382 bp and 1873 bp,respectively.Each fragment contains an ORF,ORF1 encodes RdRp,ORF2-3 encodes proteins with unknown functions,and ORF4 has any information.The virus was found to exist in two forms,BH19-3V and BH19-4V,respectively.Both forms can reduce host pathogenicity.Based on the above research results,pathogenic fungi of canker and dieback of jujube are rich,and the pathogenic fungi of jujube dry rot contain a rich variety of fungal viruses.There are differences in the virus types of pathogenic fungi from different sources,and the viruses of different pathogenic species are also different.The expression level of mycovirus may affect the virulence of the host,and the mycovirus may also affect the morphology of colony morphology.