Gene Expression Profile Of Ralstonia Solanacearum In The Potato Niche

Plant root secretion can be regarded as a signal molecule,which exerts impact on the niche of microorganisms.The different pathogen' responses to signals of different hosts depend on specific rhizosphere microbial populations.The research of baterial expression pattern in plant secretion environment is limited.In particular,the molecular mechanism of interaction between potato and Ralstonia solanacearum in the niche is rarely reported.In this study,we obtained gene expression profile of R.solanacearum strain PO41 under the root secretions environment of Solanum tuberosum 8h,16 h and 24 h post innoculation with RNA microarray technology.At the same time,we get R.solanacearum strain T518 gene expression profile under the root secretions environment of Solanum lycopersicum,and obtain the gene expression profiles of strain GMI1000 under the root secretions environment of Arabidopsis thaliana.In order to reveal the molecular mechanism of expression regulation at the upstream or even the source of gene expression network,several bioinformatic tools were usedto study pathogen genes of pathogenic or closely related to pathogenic,in which the gene expression pattern,gene ontology,functional cluster and pathway analysis were used.The results showed that the pathogenic factors of R.Solanacearum were mainly concentrated in the export of toxic protein(Sec pathway,Tat pathway,and T3SS),the aggregation and transfer of exopolysaccharides,and the chemotactic movement and adhesion of flagellum.In the protein export pathway,the pathogenic factors of atypical export pathway were mainly concentrated at the pathways of Sec(sec B,sec DF,yidc)and Tat(tat A,tat C),which promoted the export of unfolded toxic proteins.In Type ? secretion systems,however,we only found that fli IATPase showed obvious up-regulated expression 8h after infection in the potato rhizosphere ecological niche.But in the rhizosphere ecological niche of Arabidopsis thaliana,fli H and fli P were obvious up-regulated.In the biosynthesis pathway of exopolysaccharides,glucose-1-phosphate was raw material for synthesizing EPS,UDP-Gal was an important donor of transglycosylationreaction during this pathway,the expression of enzymes(phosphoglucomutase and epimerase)synthesizing the two materials was up-regulated,providing adequate raw material for the synthesis of EPS.In the chemotactic movement of flagellum,we found that the expression of chemotactic receptor and motor were obviously up-regulated.According to the expression quantity of motor protein during infection process,we assumed that Ralstonia solanacearum already colonized to the roots within 24 h during the early stage of infection.In the potato niche we found that the expression of both the mobility factor gene fli C and the export of flagelliform silk protein control gene flg E were up-regulated to improve the adhesion effect of flagellum.However,in the niche of Arabidopsis thaliana,gene fli C was down-regulated significantly,which obviously inhibited the adhesion effect of flagellum.However,we also found that gene mot B was significantly up-regulated,enhanced the flagellum movement,and implied that in the early stages of invasion effect of the flagellum during the A.thaliana-R.solanacearum interaction,flagellum has not adhered to the rhizosphere surface.This also indicates that the rhizosphere ecological niche of different plants can affect the Ralstonia solanacearum rate of infection.The gene expression profile of Ralstonia solanacearum at the niche of potato was determined here,and the results of expression analysis of key genes related to pathogenicity would be helpful to reveal the molecular mechanism of potato and R.solanacearum,to provide a theoretical basis for the molecular mechanism of resistance to potato bacterial wilt.