tepR encoding a bacterial enhancer‐binding protein orchestrates the virulence and interspecies competition of Burkholderia glumae through qsmR and a type VI secretion system

摘要

The pathogenesis of the rice pathogenic bacterium is under the tight regulation of the / quorum‐sensing (QS) system. , encoding a group I bacterial enhancer‐binding protein, negatively regulates the production of toxoflavin, the phytotoxin acting as a major virulence factor in . In this study, through a transcriptomic analysis, we identified the genes that were modulated by and/or the / QS system. More than half of the differentially expressed genes, including the genes for the biosynthesis and transport of toxoflavin, were significantly more highly expressed in the Δ mutant but less expressed in the Δ ( / QS‐defective) mutant. In consonance with the transcriptome data, other virulence‐related functions of , extracellular protease activity and flagellum‐dependent motility, were also negatively regulated by , and this negative regulatory function of was dependent on the IclR‐type transcriptional regulator gene . Likewise, the Δ mutant exhibited a higher level of heat tolerance in congruence with the higher transcription levels of heat shock protein genes in the mutant. Interestingly, also exhibited its positive regulatory function on a previously uncharacterized type VI secretion system (denoted as BgT6SS‐1). The survival of the both Δ and Δ (BgT6SS‐1‐defective) mutants was significantly compromised compared to the wild‐type parent strain 336gr‐1 in the presence of the natural rice‐inhabiting bacterium, sp. RSPAM1. Taken together, this study revealed pivotal regulatory roles of in orchestrating multiple biological functions of , including pathogenesis, heat tolerance, and bacterial interspecies competition.