Functional Analysis Of VmSom1?VM1G₀6657?VM1G₀7354 And VM1G₁1970 In Valsa Mali

Valsa canker of apple is a damaged stem disease caused by Valsa mali,which has become a serious obstacle to the development of the apple industry.It is necessary to determine the growth,development and pathogenic mechanism of pathogens for disease prevention and control.Som1 is an important transcription factor for the cAMP/PKA,which regulates the growth,morphological differentiation and pathogenicity of pathogenic fungi.By transcriptome analysis,three significant differentially expressed genes VM1G₀6657,VM1G₀7354,and VM1G₁1970 were found,their function is unknown.This study mainly investigated the function of VmSom1 and the three differentially expressed genes described above.The detailed information,domains and phylogenetic relationships of these four genes were obtained by bioinformatics analysis.The four genes were knocked out and complemented.The growth,stress tolerance and pathogenicity of four knockout mutants,complemented strains and wild strains were analyzed,and the same time,the effect of VmSom1 deletion on the expression of three other genes were analyzed.The results are as follows:1.Bioinformatics results showed that the VmSom1?KUI74346.1?was 2723 bp in length,located at 62925 bp-71947 bp of chromosome 12,encoding 824 amino acids,containing four introns and five exons.The VmSom1 contains LisH domain and nuclear localization signal peptide?NLS?,and it had highly homology with MoSom1 and SomA.The VM1G₁1970?KUI74531.1?was 502 bp in length,located at 56156 bp-56647 bp of chromosome 13,encoding 128 amino acids.The VM1G₁1970 contains the bromodomain domain.VM1G₀6657?KUI71651.1?was 1050 bp in length,and located at 209859 bp-210908 bp of chromosome 7.VM1G₀7354?KUI71339.1?was 2120 bp and also located at 2748276 bp-2750395 bp of chromosome 7,encoding 531 amino acids,containing three introns and four exons,and there was a Myb_DNA-bind₆ domain in VM1G₀6657.2.The growth and development showed that the ?VmSom1 aerial hyphae grew weakly,the surface of the colony was moist,the growth was significantly slowed down,and ?VmSom1 did not produce fruit bodies at all times,indicating that the VmSom1 had an important regulatory effect on the growth and sporulation.?VM1G₁1970 had no significant difference in growth and colony morphology with wild type,but the sporulation amount was significantly reduced compared with wild type,indicating that VM1G₁1970 has an important regulatory effect on sporulation;There was no significant difference between the wild type and sporulation,indicating that the other two genes did not significantly regulate the growth and sporulation.3.Stress tolerance results showed that four strains were inhibited in the growth of the medium using cell wall stress factors?Congo red,CFW,SDS?and osmotic stress factors?NaCl,sorbitol?.The inhibition rate of the knockout mutants of the four genes were not significantly different from that of the wild type,indicating that the VmSom1,VM1G₀6657,VM1G₀7354,and VM1G₁1970 had no significant regulatory effects on cell wall and osmotic stress.4.The virulence assay showed that there was no significant difference in pathogenicity between wild type sdau 11-175 strain and ?VM1G₀6657,?VM1G₀7354,?VM1G₁1970,while ?VmSom1 pathogenicity was significantly reduced.It indicated that VmSom1 has important regulation on the pathogenicity,while VM1G₀6657,VM1G₀7354 and VM1G₁1970 genes have no obvious regulatory effect on the pathogenicity.5.The results of qRT-PCR showed that the deletion of VmSom1 reduced the expression levels of genes VM1G₀6657 and VM1G₁1970 by 3.3-fold and 4.9-fold,respectively,while the expression of VM1G₀7354 gene was up-regulated by 7.6-fold.It indicating that VmSom1 positively regulates VM1G₀6657 and VM1G₁1970 gene,negatively regulates the expression of VM1G₀7354.In summary,the VmSom1 has an important role in regulating the growth,sporulation and pathogenicity of Valsa mali;the VM1G₁1970 has an important regulatory effect on sporulation;the genes VM1G₀6657 and VM1G₀7354 had not obvious regulatory effect on the growth and development of pathogens,and the regulation of VmSom1 gene on their expression is inconsistent.