[Deletion mutation of rbfCxoo, encoding a putative glycosyltransferase in Xanthomonas oryzae pv. oryzae leads to enhanced virulence expression].

ABSTRACT

OBJECTIVE: To better understand the structure and biological function of rbfCxoo, a gene with the putative function in lipopolysaccharide O-antigen synthesis in Xanthomonas oryzae pv. oryzae (Xoo), the causal pathogen of bacterial blight of rice. METHODS: The molecular identification and function analysis of rbfCxoo were performed through gene cloning, sequencing and deletion analysis. RESULTS: The sequence of rbfCxoo cloned from the genomic DNA of wild-type PXO99(A) was the same as that of the sequenced strain KACC10331. There were glycosyltransferase domains (Glycos_transf_2) at N and C terminal of RbfCxoo respectively. The deletion mutant delta rbfCxoo generated through a double crossover recombination and validated by PCR assay displayed the reduced flagellin glycosylation and no change in lipopolysaccharide O-antigen synthesis compared with PXO99(A). Moreover, no significant changes in flagellar mobility, biofilm formation and production of extracellular cellulase and xylanase in vitro were observed in delta rbfCxoo compared to PXO99(A). Most importantly, the deletion mutation of rbfCxoo resulted in enhanced virulence and gene expression. CONCLUSION: RbfCxoo might be related to flagellin glycosylation and virulence expression in Xoo.