Study On The Biological Functions Of Effector SS1G＿08907 Of Sclerotinia Sclerotiorum

Sclerotinia sclerotiorum is a necrotrophic plant pathogenic fungus that causes a variety of plant diseases worldwide and causes serious economic losses in agricultural production.Studying on pathogenesis of S.sclerotiorum can not only provide potential target for Sclerotinia disease management,but also offer a reference basis for breeding of crops resistant to S.sclerotiorum.In this study,SS1G＿08907 gene was significantly upregulated in the infection stage from the transcriptome database of S.sclerotiorum.It was confirmed by qRT-PCR that the expression level of SS1G＿08907 was increased by 29.87 times when S.sclerotiorum infected A.thaliana leaves at 3 hours post inoculation(hpi).Moreover,SS1G＿08907protein could inhibit chitin-induced ROS burst,indicating that SS1G＿08907 may play an important role during infection of S.sclerotiorum.SS1G＿08907 widely distributed in plant pathogenic fungi,it encodes 515 amino acid residues,of which the first 19 amino acids are signal peptide sequences.Secretory verification results show that the protein is secretory,the results of subcellular localization showed SS1G＿08907 that localization in the nucleus and cell cytoplasm in plants.Transient expression of SS1G＿08907 in tobacco leaves can reduce the expression of immune-related genes ERF1 and PR1,and promote S.sclerotiorum infection.However,compared with 1980 strains,ΔSS1G＿08907 mutants have no significant differences in mycelial growth,sclerotial development,cushion formation,oxalic acid production,and virulence.In order to further clarify the function of SS1G＿08907 in plants,35s:SS1G＿08907transgenic plants were obtained with Arabidopsis thaliana Col-0 as the background.Compared with Col-0,there are no significant differences in growth and development among SS1G＿08907 transgenic plants.However,the chitin-induced ROS burst and the expression of immune-related genes in 35s:SS1G＿08907 transgenic plants was significantly reduced,and they were more susceptible to S.sclerotiorum WT strain 1980.Candidate plant proteins interacting with SS1G＿08907 were screened by protein LCMS/MS technology,and the interaction between SS1G＿08907 and host protein At GAPCs was verified by Luciferase complementary,and they were co-localized in the cytoplasm and nucleus of plant cells.In conclusion,although the knock-out of gene SS1G＿08907 does not affect the virulence of S.sclerotiorum,which may be related to its strong virulence and the presence of numerous pathogenic factors.But overexpressing of SS1G＿08907 can inhibit the host plant immune response,thus affecting the resistance of host plants,indicating that the secreted protein may play a role in the infection of S.sclerotiorum.These results laid the foundation for further revealing the biological function of the secreted protein SS1G＿08907.