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

Background: To facilitate infection, Xanthomonas oryzae pv. oryzae (Xoo), the bacterial blight pathogen of rice, needs to degrade hydrogen peroxide (HO) 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.

Alternative sigma factor RpoN2 is required for flagellar motility and full virulence of Xanthomonas oryzae pv. oryzae.

Xanthomonas oryzae pv. oryzae (Xoo), the bacterial blight pathogen of rice, harbors a single polar flagellum for motility. How the flagellar system is regulated and how it is related to bacterial pathogenesis are not well understood.

[Binding of transcription regulator Clpxoo to promoter of endoglucanase gene engAxoo was inhibited by c-di-GMP in Xanthomonas oryzae pv. oryzae].

Objective: To understand the regulatory mechanism by cyclic diguanylate (c-di-GMP) receptor and transcriptional regulator Clpxoo of expression of endoglucanase gene (engAxoo) in Xanthomonas oryzae pv. oryzae, the bacterial leaf blight pathogen of rice.

Methods: A plasmid to expressclpxoo gene was constructed and transformed into Escherichia coli for expression by isopropylthio-beta-D-galactoside (IPTG) induction.

The degenerate EAL-GGDEF domain protein Filp functions as a cyclic di-GMP receptor and specifically interacts with the PilZ-domain protein PXO_02715 to regulate virulence in Xanthomonas oryzae pv. oryzae.

Degenerate GGDEF and EAL domain proteins represent major types of cyclic diguanylic acid (c-di-GMP) receptors in pathogenic bacteria. Here, we characterized a FimX-like protein (Filp) which possesses both GGDEF and EAL domains in Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight of rice.

A novel two-component system PdeK/PdeR regulates c-di-GMP turnover and virulence of Xanthomonas oryzae pv. oryzae.

Two-component systems (TCS) consisting of histidine kinases (HK) and response regulators (RR) play essential roles in bacteria to sense environmental signals and regulate cell functions. One type of RR is involved in metabolism of cyclic diguanylate (c-di-GMP), a ubiquitous bacterial second messenger. Although genomic studies predicted a large number of them existing in different bacteria, only a few have been studied.

[Gene deletion and functional analysis of the EAL domain protein vieAxoo in Xanthomonas oryzae pv. oryzae].

Objective: To better reveal the functions of key members involved in cyclic di-GMP signal metabolism pathways in the bacterial blight pathogen of rice Xanthomonas oryzae pv. oryzae (Xoo).

Methods: vieAxoo (PXO 04753), a gene putatively encoding the EAL domain proteins was investigated by gene deletion mutation using the marker exchange, complementation and phenotypic analysis.

[Diffusible signal factor production and virulence expression in deltarpfFxoo, deltarpfCxoo and deltarpfGxoo, the gene deletion mutants of DSF/Rpf signaling proteins of Xanthomonas oryzae pv. oryzae].

Objective: To better elucidate the functions of RpfFxoo, RpfCxoo and RpfGxoo, 3 proteins of diffusible signal factor (DSF)-dependent cell-cell signaling system in regulation of virulence expression of Xanthomonas oryzae pv. oryzae (Xoo).

Method: Deltarpfxoo, the gene deletion mutants were generated from PXO99(A), the wild-type strain of Xoo via marker-exchanging and DSF biosynthesis and extracellular polysaccharide production and virulence to rice of the mutants were assayed.

[Ferric iron absorption in deltar p f F xoo, a gene deletion mutant of Xanthomonas oryzae pv. oryzae, assayed using atomic absorption spectrophotometry].

The ferric iron absorption is one of the most important limiting factors of bacterial growth of Xanthomonas oryzae pv. oryzae. It has been previously speculated that r p f F xoo might be involved in the ferric iron metabolism of the pathogen.

[Identification and functional analysis of Tdrxoo, the member of TonB-dependent-receptor family proteins in Xanthomonas oryzae pv. oryzae].

Objective: To demonstrate the novel regulatory pathways mediated in bacterial pathogenicity and motility in Xanthomonas oryzae pv. oryzae (Xoo), the casual agent of bacterial blight in rice.

Methods: Molecular identification and functional characterization of Tdrxoo, which interacts with GacAxoo of the two-component regulatory system (GacSxoo/GacAxoo) in Xoo, were performed through gene cloning, sequencing and disrupt analysis.

[Roles of OxyRxoo, a transcriptional regulator of Xanthomonas oryzae pv. oryzae in regulation of detoxification of hydrogen peroxide].

Objective: OxyRxoo is a homologue of OxyR from Xanthomonas oryzae pv. oryzae (Xoo), the pathogen of bacterial blight of rice. To elucidate the role of OxyRxoo in detoxification of hydrogen peroxide.

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

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.

The complete nucleotide sequence of the barley yellow dwarf GPV isolate from China shows that it is a new member of the genus Polerovirus.

The complete nucleotide sequence of the ssRNA genome of a Chinese GPV isolate of barley yellow dwarf virus (BYDV) was determined. It comprised 5673 nucleotides, and the deduced genome organization resembled that of members of the genus Polerovirus. It was most closely related to cereal yellow dwarf virus-RPV (77% nt identity over the entire genome; coat protein amino acid identity 79%).

[Molecular identification and functional analysis of Clpxoo, a homologue to the nucleotide receptor protein in Xanthomonas oryzae pv. oryzae].

Objective: To better understand the mechanisms of cyclic di-GMP signaling in Xanthomonas oryzae pv. oryzae (Xoo),the casual pathogen of bacterial blight of rice, molecular identification of Clpxoo.

Methods: A putative signal receptor protein was performed through gene cloning, sequencing and deletion analysis.