Functional Analysis Of Galactose Uridyltransferase Gene In Sclerotinia Sclerotiorum And The Induced Host PR Proteins Regulation

Sclerotinia sclerotiorum is capable of infesting a wide range of host plants and is a typical dead nutritional plant pathogenic fungus.Sclerotiose caused by S.sclerotiorum is worldwide that can cause great damage to various cash crops.In this study,we targeted the glucose metabolism pathway of S.sclerotiorum,to investigate the function of galactosyl uridyltransferase Ss GALT1 gene of S.sclerotiorum,and construct a host PR protein gene silencing vector to explore the expression and regulation of PR5 protein in Physalis pubescens.Main findings.(1)Bioinformatics characterization and expression analysis of Ss GALT1 protein in S.sclerotiorum.The results showed that Ss GALT1 protein of S.sclerotiorum is a member of galactose-1-phosphate uridyltransferase protein family,consisting of 382 amino acids,no transmembrane helix,no signal peptide shear site,and probably a hydrophilic secretory protein.In addition,the Ss GALT1 gene of S.sclerotiorum showed differential expression during fungal growth and development and pathogenesis.Among them,the expression of Ss GALT1 gene was up-regulated at the early stage of infestation(48 h)and during maturation(72 h)compared to the previous time point.(2)Construction of Ss GALT1 gene deletion mutants in S.sclerotiorum.The Ss GALT1 gene deletion mutant of S.sclerotiorum was obtained by homologous recombination of the Ss GALT1 gene mediated by the p CX62 vector using protoplast transformation methods,which was verified by PCR to show that the target gene Ss GALT1 fragment was successfully replaced by the hph gene.(3)Phenotypic analysis of the Ss GALT1 gene of S.sclerotiorum.The deletion of the Ss GALT1 gene in S.sclerotiorum affected growth and development,as evidenced by a delay in the growth of mut1 mycelium of about 5.5% and mut2 mycelium of about 50% compared to the wild type,the failure to produce mature sclerotium at the maturation stage(8 d),and the absence of oxalic acid secretion,but a decrease in pathogenicity of about 54.5%.(4)Induction of host PR protein regulation during pathogenesis by S.sclerotiorum.The expression level of host PR was altered following infestation of the host by S.sclerotiorum.Among them,PR1 expression was significantly up-regulated more than 40-fold,PR5 expression was up-regulated about 6-fold at the late stage of infestation(72 h),and PR10 expression was stable compared with non-infested healthy plants.The host PR protein VIGS vector was constructed and transformed into the host plants.The resistance of tomato and sunflower transformed by S.sclerotiorum decreased about 79.9% and 21.4%,respectively,indicating that the S.sclerotiorum infestation process was able to induce the regulation of host PR protein expression.This study investigated the influence of genes in the carbon metabolism of S.sclerotiorum on growth and development as well as pathogenesis,and constructed VIGS systems for different host plants in the direction of S.sclerotiorum induced PR protein expression,which provided a theoretical basis for the subsequent exploration of different gene functions and PR protein regulation in S.sclerotiorum,and designed effective S.sclerotiorum gene targeting drugs based on the results.