The Function Analysis Of SsPemG1, A Homolog Of Protein Elicitor In Sclerotinia Sclerotiorum

Sclerotinia sclerotiorum(Lib.)de Bary is a sclerotium-producing necrotrophic fungal pathogen and has a worldwide distribution which is a serious threat to the safety of rape production,and resulting in huge economic losses.Because of the disadvantages of traditional control methods getting bigger,it is urgent to find a new safe and efficient microbial pesticide by studying the mechanism of the disease from the genetic level.With the completed of S.sclerotiorum genome sequencing,the DNA transformation system and RNA interference technology is gradually mature,which provides convenience for the study of functional genes of S.sclerotiorum.Plants have evolved a complex system of immune responses to defend against microbial pathogens.And elicitors can stimulate plant to form programmed cell death rapidly to prevent the further spread of pathogenic bacteria.Therefore,the study of elicitor is significant to develop a new safe and efficient microbial pesticide.A novel protein elicitor from Magnaporthe grisea(GenBank accession number:EF062504),named PemG1,has a great value in manipulating the inducible responses to resistant against the blast fungus M.grisea in rice.In this study,we characterized the protein SsPemG1 in S.sclerotiorum,a homolog of PeMG1 in M.grisea.Sequence analysis revealed that they share the same function domains and higher similarity sequence.In order to research the roles of SsPemG1 in the S.sclerotiorum,firstly we had reproducted the conservative SsPemG1 gene to format the SsPemG1 silenced expression vector named Ss PemG1-pSilent-1,and then utilized PEG to mediate the S.sclerotiorum transformation experiment.The mutant strains M6 and M9 with good silencing effect were screened out by the experiment of the resistance to the hygromycin B and the qRT-PCR.The function of SsPemG1 in S.sclerotiorum was defined by analyzing the phenotypic differences and bioinformatics information.Phenotypic analysis showed that: SsPemG1 silencing induced strong virulence in both detached leaves and intact plants.Further research showed that: a higher growth rate,reduced sodium chloride(NaCl)and sodium dodecyl sulfate(SDS)susceptibility,more infection cushions and greater cell-wall-degrading enzymes(CWDEs)activities all contributed to this virulence.The results of bioinformatics prediction show that the main function of SsPemG1 is to combine RNA and regulate transcription and translation,which was consistent with the results of phenotype experiments.These data will help us better understand the function of SsPemG1 in S.sclerotiorum,provide a new method to study elicitors and a theoretical foundation for disease control of this fungus.