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

Abstract:

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 PXO99A 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 △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 PXO99A. Moreover, no significant changes in flagellar mobility, biofilm formation and production of extracellular cellulase and xylanase in vitro were observed in △rbfCxoo compared to PXO99A. 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.

Key words:Keywords: Xanthomonas oryzae pv. oryzae; rbfCxoo; glycosyltransferase; flagellin glycosylation; virulence