title: Identification and characterization of a novel gene, hshB, in Xanthomonas oryzae pv. oryzicola co-regulated by quorum sensing and clp.
abstract: Virulence factors of Xanthomonas oryzae pv. oryzicola, the causal agent of bacterial leaf streak in rice, are regulated by a diffusible signal factor (DSF)-dependent quorum-sensing (QS) system. In this study, a novel pathogenicity-related gene, Xoryp_010100018570 (named hshB), of X. oryzae pv. oryzicola was characterized. hshB encodes a hydrolase with a putative signal peptide, which is a homolog of imidazolonepropionase. Bioinformatic analysis showed that hshB is relatively conserved in the genus Xanthomonas but the homologous gene of hshB was not found in X. oryzae pv. oryzae. Reverse-transcription polymerase chain reaction (PCR) analysis showed that hshB and its upstream gene, Xoryp_010100018565 (named hshA), are co-transcribed in X. oryzae pv. oryzicola. Subsequent experimental results indicated that mutation of hshB remarkably impaired the virulence, extracellular protease activity, extracellular polysaccharide production, growth in minimal medium, and resistance to oxidative stress and bismerthiazol of X. oryzae pv. oryzicola. Mutation of clp, encoding a global regulator, resulted in similar phenotypes. Real-time PCR assays showed that hshB transcription is positively regulated by clp and DSF, and induced by poor nutrition. Our study not only found a novel gene hshB regulated by DSF-dependent QS system and clp but also showed that hshB was required for virulence of X. oryzae pv. oryzicola.
authors: College of Plant Protection and Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing 210095, China.
authors: Yancun
authors: Y
authors: Zhao
authors: Guoliang
authors: G
authors: Qian
authors: Jiaqin
authors: J
authors: Fan
authors: Fangqun
authors: F
authors: Yin
authors: Yijin
authors: Y
authors: Zhou
authors: Chunhui
authors: C
authors: Liu
authors: Qin
authors: Q
authors: Shen
authors: Baishi
authors: B
authors: Hu
authors: Fengquan
authors: F
authors: Liu
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009154:Mutation; D012275:Oryza / Q000382:microbiology*; D016877:Oxidants / Q000494:pharmacology; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D053038:Quorum Sensing; D013830:Thiadiazoles / Q000494:pharmacology; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism; D014974:Xanthomonas / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D016877:Oxidants; D013830:Thiadiazoles; D037521:Virulence Factors; C538720:bismerthlazol; D006861:Hydrogen Peroxide; D000581:Amidohydrolases; C587551:hshB protein, Xanthomonas oryzae