Molecular Identification Of Novel Viruses Of Auricularia Heimuer And Their Effect On Strains

Auricularia heimuer is one of the main cultivated species of edible fungi in China.However,diseases,mycelium aging,and strain degeneration are the main production constraints of A.heimuer worldwide.Mycoviruses are known to infect edible fungi and may cause phenotypic and physiological changes in their hosts.In this study,I conducted a preliminary exploration of the presence of viruses in A.heimuer,the identification of virus types,the relationship between virus phylogeny,the effects of the viruses on phenotypic and physiological changes in the mycelia,mycelium aging,and the matrix-degrading enzyme activity.The research on mining,phylogenetic analysis of viruses,the relationship between the viruses and mycelial aging of A.heimuer,and cultivation of A.heimuer provides resources and lays a foundation for future work on managing diseases and improving A.heimuer.In this paper,we extracted total RNA from various A.heimuer trains and used metactranscriptome sequencing based on Illumina Hi Seq sequencing technology to obtain contigs containing viruses.According to the obtained contigs sequence,we designed virus detection primers to determine the target strain.A positive single-stranded RNA virus was isolated from strain CCMJ1271,which belongs to the unclassified virus of family Virgaviridae.It was named Auricularia heimuer mycovirgavirus 1(Ah MV1).The full-length c DNA of Ah MV1 is 9,934 bp,which includes a poly(A)structure and encodes one large and two small Open Reading Frames(ORFs).ORF1 encodes an RNA-dependent RNA polymerase(Rd Rp),ORF2 encodes a movement protein-like homologous to movement proteins of plant virgaviruses,and ORF3 encodes a coat protein(CP).Because of the unique poly(a)structure of fungal viruses in this family and the few putative movement protein structures in fungal viruses,it is suggested to establish a new genus mycovirgavirus in the family virgaviridae to contain Ah MV1 and the viruses with a similar structure.The genome sequence of the virus has been registered in Gen Bank(No.MN928963).A positive single-stranded RNA virus with a full-genome sequence length of 7,127 bp was isolated from strain CCMJ1296.It is a new member of the family Fusariviridae and named Auriuria heimuer fusarivirus 1(Ah FV1).According to the genome structure analysis,the virus contains two partially overlapped ORFs and a poly(A)tail structure,in which ORF1 contains conservative regions Rd Rp and Hel,and the ORF2 coding function is unknown.Moreover,it is proposed to subdivide the currently recognized fusariviruses into at least two other genera based on their sequence length and genomic organization.The genome sequence of the virus has been deposited in the Gen Bank database(No.MT232758).A single negative-strand RNA virus was isolated from strain CCMJ1222 and was named Auriuria heimuer negative-stranded RNA virus1(Ah Ns RV1).It is a new member of the family Mymonaviridae.Its genome length is 11,441 bp,and there are six ORFs without overlap,and the interval is highly conserved between each ORF,which is consistent with the characteristics of a single negative-strand RNA virus.Due to the small number of viruses in the family,no detailed genus has been carried out at present.With the successive reports of negative-strand RNA viruses,it is suggested that the currently published negative-strand viruses shall be subdivided into at least two or three new genera according to the sequence length and genome structural characteristics.The virus has been deposited in the Gen Bank database(No.MT259204).The mycelial growth of three virus-infected strains and a strain of virus not detected in different periods was observed.The results showed that the mycelia of each strain were dense and grew well at the early stage of growth.Increasing the incubation time gradually decreased the number of aeromycelia and growth on the attached medium.The virus-infected strains showed increased melanin secretion and decreased with advancing mycelia age.However,the strain of virus not detected did not show obvious melanin secretion.The activity of laccase and acid xylanase enzymes in virus-infected strains decreased with mycelial aging but was not significantly different from the strain of virus not detected.Contrarily the cellulase activity increased after decreasing in both virus-infected and strain of virus not detected.Taken together,the results indicate that the melanin ecretion by A.heimuer aging mycelia may be related to the virus infecting the strain.However,the presence of the virus does not significantly affect the change of matrix-degrading enzyme after aging,therefore,the specific mechanism of this phenomenon needs to be further explored.