Research On The Mechanism Of Protein Elicitor SsSm1 In The Development And Pathogenesis Of Sclerotinia Sclerotiorum

Sclerotinia sclerotiorum(Lib.)de Bary is an important phytopathogen with a worldwide distribution.This fungus has a wide range of hosts and infects more than 400 host species,including many important crops.Sclerotinia stem rot caused by this fungus brought great harm to rapeseed production and has led to great economic loss.During the evolution,plants have evolved a complex system of immune responses that depend on the innate immunity of each cell and systemic signals from the infected site to deal with external pathogens.In the interaction between pathogens and the host,a variety of signaling molecules will be produced,and an elicitor is one of the most important substances.Elicitor species are diverse and include polysaccharides,glycoproteins,polypeptides,among others.This study describes a protein that has high homology with the Trichoderma elicitor Sm1 and was found in the genome of S.sclerotiorum.This protein was named as SsSm1.In this study,the full-length sequence of SsSm1 was cloned.The heterologous expression vector and Transient expression vector of SsSm1 were constructed and expressed on Escherichia coli cells and Nicotina benthamiana leaves,respectively.Next,RNA interference was used to explore the role of SsSm1 in the development and pathogenicity of S.sclerotiorum.The main results are as follows:(1)The protein of heterologous expression led to the formation of lesions in tobacco that closely resemble hypersensitive response lesions;Transient expression of the encoding gene of SsSm1 in tobacco leaves also caused hypersensitive response.(2)The hyphal growth and pathogenicity of silenced transformants were shown to be obviously lagging and branched abnormally.Transformants produced less infection cushions and deformed sclerotiorum.(3)SsSm1 silencing caused weak tolerance to NaCl,sorbitol and SDS.(4)The pathogenicity of SsSm1 silenced strains was greatly reduced.Based on the above results,This protein may be related to the development of hyphae,infection cushions,but the specific molecular mechanism needs to be studied further.These data will help us better understand the function of SsSm1 in S.sclerotiorum,provide a theoretical foundation for disease control of this fungus.