西瓜副噬酸菌RpoN(σ54因子)功能分析OA

RpoN,also known as the α54 factor,is a group of DNA-binding proteins in bacteria.RpoN assists RNA poly-merase in gene transcription initiation and is involved in various critical biological processes,including virulence,cell mo-tility,flagellar assembly,and nitrogen assimilation.In this study,two RpoN-coding genes(designated rpoN1 and rpoN2),were found in the Paracidovorax citrulli genome.The rpoN1 and rpoN2 mutant strians and comlementary strains were constructed based on the wild-type strain Aac5.And then,genetic phenotypic determination,RNA-seq and EMSA(electro-photic mobility shift assay)were performed to explore the function of RpoN1 and RpoN2 in P.citrulli and their difference.The results showed that the deletion of either rpoN gene significantly impaired virulence and motility of P.citrulli group Ⅱ strain Aac5,as well as retarded growth in M9 minimum medium.In addition,the deletion of rpoN1 alone affected P.citrul-li seed adhesion and nitrate assimilation,while deletion of rpoN2 alone enhanced biofilm formation ability.RNA-seq anal-ysis revealed significantly reduced expression of pilA,a gene related to type Ⅳ pili synthesis in ΔrpoN1.Further investiga-tion using EMSA confirmed the binding of RpoN1 to pilA.Overall,our findings demonstrate that RpoN1 and RpoN2 are not redundant in P.citrulli,but rather,both play crucial and distinct roles in the pathogenic mechanisms of bacterial fruit blotch.This study provides an important theoretical basis for scientific prevention and control of bacterial fruit blotch.