Transcriptome analysis of Xanthomonas oryzae pv. oryzicola exposed to H2O2 reveals horizontal gene transfer contributes to its oxidative stress response

Xanthomonas oryzae pv. oryzicola ( Xoc ), the causal agent of bacterial leaf streak, is one of the most severe seed-borne bacterial diseases of rice. However, the molecular mechanisms underlying Xoc in response to oxidative stress are still unknown. In this study, we performed a time-course RNA-seq analysis on the Xoc in response to H 2 O 2 , aiming to reveal its oxidative response network. Overall, our RNA sequence analysis of Xoc revealed a significant global gene expression profile when it was exposed to H 2 O 2 . There were 7, 177, and 246 genes that were differentially regulated at the early, middle, and late stages after exposure, respectively. Three genes ( xoc_1643 , xoc_1946 , xoc_3249 ) showing significantly different expression levels had proven relationships with oxidative stress response and pathogenesis. Moreover, a hypothetical protein (XOC_2868) showed significantly differential expression, and the xoc_2868 mutants clearly displayed a greater H 2 O 2 sensitivity and decreased pathogenicity than those of the wild-type. Gene localization and phylogeny analysis strongly suggests that this gene may have been horizontally transferred from a Burkholderiaceae ancestor. Our study not only provides a first glance of Xoc ’s global response against oxidative stress, but also reveals the impact of horizontal gene transfer in the evolutionary history of Xoc .