The Roles Of Fad P In Regulation Of Ralstonia Solanacearum Pathogenesis And Genome Analysis Of Ralstonia Phage P2TB1556

Ralstonia solanacearum, a worldwide important plant pathogenic bacterium, can survive in water, soil, and among the roots of nonsusceptible plant hosts. It has a wide host range and could infect more than 50 families of the 400 kinds of plants, including solanaceae plant, and it causes the bacterial wilt of plants, which is the devastating damage in tropical and subtropical regions. Yet it has not ideal control agents. Therefore, the researches on R. solanacearum, and the explorations of the new way for prevention and control of bacterial wilt, have much important scientific significances.In this study, firstly, the fadP gene of R. solanacearum Tm1401 strain was analyzed by bioinformatics, and then this gene was cloned. Secondly, in order to research the function of the fadP gene, the genes deletion mutants were constructed by using homologous recombination. Phenotype of the mutants, the complementary strains and the wild type Tm1401 strain were compared. Bioinformatics analysis based on the complete genome sequence of R. solanacearum Tm1401 strain revealed that the fadP gene is 591 bp,encoded 196 amino acids. Nucleotide and protein sequence of gene fadP were compared with those of FQY₄, YC45 and GMI1000 strain, the consistency is 99%. The function of gene and the structure of its coding for protein were forecasted through bioinformatics. The result is that FadP protein is a homodimer. The results of phenotypic determination were those: compared to wild type, the growth rate of ?fadP was reduced, and the ability of causing the disease is lost. Meanwhile, the activities of extracellular cellulose and the bacterial motility were decreased. Whereas, there were no significant changes in the production of extracellular polysaccharide?EPS? and the symptoms on hypersensitive reaction?HR? on tobacco.To further understand the virulence mechanisms of Tm1401, the high-throughputRNA sequencing technology?RNS-Seq? was utilized to interrogate R. solanacearum wild strain Tm1401 and ?fadP transcriptome. Transcriptome comparison revealed 848 differentially expressed genes?FDR?0.001 and |log2Ratio|?1?, of which 505 were up-regulated in ?fadP whereas 343 were down-regulated. GO functional enrichment analysis and KEGG pathway analysis of these genes, illustrated that the differentially expressed genes were enrich in biological process, cellular component, molecular function, metabolic pathways, biosynthesis of secondary metabolites and two-component system.Bacteriophages are viruses of bacteria. They are ubiquitous in nature, and are now recognized to be the most numerous entities in the biosphere. In this study, a Ralstonia phage P₂Tb1556 was observed by transmission electron microscope, its nucleic acids was extracted and then sent to company for genomic sequencing and analyses. This phage, which belongs to Caudovirales Myoviridae, is double-stranded DNA. The genomic sequencing has more than 46508 bp and 65 genes totally. The GC content is 62.329%. In 65 genes, 24 genes can't match well, and other 24 genes match with the ORF of different Burkholderia phages genomes. No potential tRNA coding regions were found in the phage genome. There are 2 possible rho-independent terminators, 69 possible promoters and no CpG lands in the genomic sequencing.