Deletion analysis of fliExoo,the gene encoding a flagellar base body protein in Xanthomonas oryzae pv.oryzae

To elucidate the function of fliExoo gene encoding a putative flagellar base body protein in Xanthomonas oryzae pv. oryzae (Xoo), the gene deletion mutant △fliExoo was generated by the GmR marker exchange from the wild-type strain PXO99A. Non-flagellum, cell precipitation in the culture and significantly attenuated motility on 0.3% semi-solid medium were observed in △fliExoo compared to those of PXO99A. While there were no apparent alterations in bacterial growth and activity of cellulase in vitro, significant decreases in extracellular polysaccharide (EPS) production and biofilm formation were found in △fliExoo. The pathogenicity on rice (Oryza sativa L cv. Nipponbare) and induction of hypersensitive response (HR) on tobacco (Nicotiana tabacum L.) were attenuated in △fliExoo. △fliExoo-C, the complementation strain restored the phenotypes of the mutant △fliExoo partially or completely. As a result, the fliExoo mutation not only influenced on flagellar motility,but also virulence-related phenotypes in Xoo.