Study On The Function Of Chemoreceptor Genes In Xonthomonas Oryzae Pv. Oryzicola

Xanthomonas oryzae pv. oryzicola(Xoc)is one of the bacterial pathogens of rice,which can infect rice leaves causing rice bacterial leaf streak(BLS),resulting in serious yield reduction of rice.Xoc mainly infects rice through stomata and wounds on leaves,and colonizes the outer body of the mesophyll tissue which resulting in intervein-chlorosis and formation of stripe disease.Up to now,the key genes of BLS resistance have not been found in rice,so it is urgent to develop effective BLS prevention and treatment methods.Understanding the pathogenic molecular mechanism of pathogenic bacteria is the basis for developing efficient and targeted drugs and methods for disease prevention and treatment.Previous studies have shown that chemotaxis plays an important role in bacterial infection,and at the same time,chemotaxis plays a key role in the early stage of bacterial infection.However,Methyl-Accepting chemotaxis,also called methylation in bacterial chemotaxis chemical signals and will transfer to the downstream,the disadvantages of a behavior,in order to make clear the function of the methylation of Xoc receptor proteins MCP,Methyl-Accepting chemotaxis of rice bacterial stripe and a flagella gene mutations,the main results were as follows:1.Through bioinformatics analysis of the genome of Xoc GX01 strain,19 mcp genes were identified,most of which were typical mcp genes.Comparative analysis by KEGG showed that XOC2399 and XOC1592 genes were incomplete in the annotation,while XOC2399 and XOC1592 genes lacked a transmembrane domain in the annotation.In the new prediction,XOC2399 and XOC1592 genes were double transmembrane domain2.The upstream and downstream fragments of mcp gene were obtained by PCR,and were connected with pK18mobsacB vector to form recombinant plasmid,and then the recombinant plasmid by using the method of three joint parents into Xoc GX01 strains,through after antibiotics screening markers such as screening and PCR test,build the gene mutant of 11 mcp and a flagellum gene mutant3.The wild-type and mutant strains of Xoc GX01 were identified by capillary method.,in identification of chemotactic Xoc GX01 strains of glucose,xylose,sucrose,fructose,leaf extract,rice milling,succinic acid,malic acid,tartaric acid,alanine,isoleucine,phenylalanine,serine,threonine and tryptophan,asparagine,valine,glutamic acid,methionine,has obvious chemotaxis Compounds with different initial responses of MCP mutants were preliminarily identified4.Phenotypic detection and pathogenicity detection were performed on 11 mcp mutants and one flagellar gene mutant,and the mutants with obvious phenotypic changes and pathogenicity changes were complemented.It was found that the deletion of △XOC2399 resulted in a slight increase in extracellular polysaccharide,a slight decrease in extracellular protease,a significant increase in motility,a significant decrease in motility,an increase in antioxidant capacity,a decrease in salt tolerance,and a significant decrease in virulence.△XOC2350 showed a significant decrease in motility.The formation ability of △XOC1592,△XOC2048 and△XOC2854 biofilms decreased.The pathogenicity of △XOC2399,△XOC2048 and △XOC2854 decreased in the experiments.△XOC2350 increased pathogenicity in the experiments of pressure infiltration and spray.In the spray test,no strains caused the disease.The mcp gene was not related to the three types of pathogenic system.5.Identification of XOC2399 in chemotaxis and pathogenesis.The plasmid with △XOC2399 gene was introduced into strain XOC2399,and various phenotypes were successfully restored,such as pathogenicity,chemotaxis,motor ability and basic phenotype,etc.,indicating that XOC2399 plays an important role in the chemotaxis and pathogenesis of Xoc.In summary,this study we carried out mutational analysis of some mcp genes in Xoc GX01 strain of rice,and completed the preliminary exploration of functions of some mcp genes in Xoc GX01 bacterial strain,which provided clues for further studies on functions of MCP and provided references for prevention and treatment of bacterial stripe disease in rice.