OxyR-regulated catalase CatB promotes the virulence in rice via detoxifying hydrogen peroxide in Xanthomonas oryzae pv. oryzaeReportar como inadecuado




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BMC Microbiology

, 16:269

Microbe-host interactions and microbial pathogenicity

Abstract

BackgroundTo facilitate infection, Xanthomonas oryzae pv. oryzae Xoo, the bacterial blight pathogen of rice, needs to degrade hydrogen peroxide H2O2 generated by the host defense response via a mechanism that is mediated by the transcriptional regulator OxyR. The catalase CAT gene catB has previously been shown to belong to the OxyR regulon in Xoo. However, its expression patterns and function in H2O2 detoxification and bacterial pathogenicity on rice remain to be elucidated.

ResultsThe catB gene encodes a putative catalase and is highly conserved in the sequenced strains of Xanthomonas spp. β-galactosidase analysis and electrophoretic mobility shift assays EMSA showed that OxyR positively regulated the transcription of catB by directly binding to its promoter region. The quantitative real-time PCR qRT-PCR assays revealed that the expression levels of catB and oxyR were significantly induced by H2O2. Deletion of catB or oxyR drastically impaired bacterial viability in the presence of extracellular H2O2 and reduced CAT activity, demonstrating that CatB and OxyR contribute to H2O2 detoxification in Xoo. In addition, ΔcatB and ΔoxyR displayed shorter bacterial blight lesions and reduced bacterial growth in rice compared to the wild-type stain, indicating that CatB and OxyR play essential roles in the virulence of Xoo.

ConclusionsTranscription of catB is enhanced by OxyR in response to exogenous H2O2. CatB functions as an active catalase that is required for the full virulence of Xoo in rice.

KeywordsXanthomonas oryzae pv. oryzae Catalase Hydrogen peroxide Virulence AbbreviationsApAmpicillin

BsBacillus subtilis

BSABovine Serum Albumin

CATCatalase

CFUColony forming units

DAB3, 3′-diaminobenzidine

EMSAElectrophoretic mobility shift assay

GmGentamycin

H2O2Hydrogen peroxide

KmKanamycin

NCBINational Center for Biotechnology Information

ODOptical density

PCRPolymerase chain reaction

PSAPeptone sucrose agar

qRT-RCRQuantitative real-time PCR

ROSReactive oxygen species

SpSpectinomycin

UUnit

XacXanthomonas axonopodis pv. citri

XooXanthomonas oryzae pv. oryzae

Electronic supplementary materialThe online version of this article doi:10.1186-s12866-016-0887-0 contains supplementary material, which is available to authorized users.

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Autor: Chao Yu - Nu Wang - Maosen Wu - Fang Tian - Huamin Chen - Fenghuan Yang - Xiaochen Yuan - Ching-Hong Yang - Chenyang He

Fuente: https://link.springer.com/







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