The xrvA gene of Xanthomonas oryzae pv. oryzae, encoding an H-NS-like protein, regulates virulence in rice

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight disease in rice, one of the most serious rice diseases. The xrvA gene from Xoo strain 13751 encodes a protein containing a histone-like nucleoid-structuring protein (H-NS) domain. The expression of xrvA in strain 13751 was enhanced in XOM2 minimal medium. Mutation of the xrvA gene of strain 13751 led to a significant reduction in virulence in the host plant rice, a delayed hypersensitive response in the nonhost castor-oil plant, a decrease in extracellular polysaccharide and diffusible signal factor production, and an increase in intracellular glycogen accumulation. Northern hybridization analyses revealed that the virulence-associated genes hrpG, hrpX, rpfC, rpfF, rpfG and gumB were downregulated in the xrvA mutant compared to the wild-type and complemented strains. Interestingly, increase of copy number of xrvA in the wild-type strain 13751 resulted in a strain showing similar phenotypes as the xrvA mutant and a reduction of the expression of gumB, hrpX, rpfC, rpfF and rpfG. These findings indicate that the xrvA gene, which is highly conserved in the sequenced strains of Xanthomonas, encodes an important regulatory factor for the virulence of Xoo.

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The Role of a Host-Induced Arginase of Xanthomonas oryzae pv. oryzae in Promoting Virulence on Rice

Phytopathology ◽

10.1094/phyto-02-19-0058-r ◽

2019 ◽

Vol 109 (11) ◽

pp. 1869-1877

Author(s):

Yuqiang Zhang ◽

Guichun Wu ◽

Ian Palmer ◽

Bo Wang ◽

Guoliang Qian ◽

...

Keyword(s):

Biofilm Formation ◽

Bacterial Blight ◽

Wild Type Strain ◽

Bacterial Pathogen ◽

Extracellular Polysaccharide ◽

Rice Cultivar ◽

Xanthomonas Oryzae ◽

Wild Type ◽

Bacterial Blight Of Rice

The plant bacterial pathogen Xanthomonas oryzae pv. oryzae causes bacterial blight of rice, which is one of the most destructive rice diseases prevalent in Asia and parts of Africa. Despite many years of research, how X. oryzae pv. oryzae causes bacterial blight of rice is still not completely understood. Here, we show that the loss of the rocF gene caused a significant decrease in the virulence of X. oryzae pv. oryzae in the susceptible rice cultivar IR24. Bioinformatics analysis demonstrated that rocF encodes arginase. Quantitative real-time PCR and Western blot assays revealed that rocF expression was significantly induced by rice and arginine. The rocF deletion mutant strain showed elevated sensitivity to hydrogen peroxide, reduced extracellular polysaccharide (EPS) production, and reduced biofilm formation, all of which are important determinants for the full virulence of X. oryzae pv. oryzae, compared with the wild-type strain. Taken together, the results of this study revealed a mechanism by which a bacterial arginase is required for the full virulence of X. oryzae pv. oryzae on rice because of its contribution to tolerance to reactive oxygen species, EPS production, and biofilm formation.

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The RpfB-Dependent Quorum Sensing Signal Turnover System Is Required for Adaptation and Virulence in Rice Bacterial Blight Pathogen Xanthomonas oryzae pv. oryzae

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-09-15-0206-r ◽

2016 ◽

Vol 29 (3) ◽

pp. 220-230 ◽

Cited By ~ 23

Author(s):

Xing-Yu Wang ◽

Lian Zhou ◽

Jun Yang ◽

Guang-Hai Ji ◽

Ya-Wen He

Keyword(s):

Quorum Sensing ◽

Bacterial Blight ◽

Xanthomonas Campestris ◽

Deletion Mutant ◽

Extracellular Polysaccharide ◽

Xanthomonas Oryzae ◽

Rice Bacterial Blight ◽

Double Deletion ◽

Diffusible Signal Factor ◽

Bacterial Blight Pathogen

Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, produces diffusible signal factor (DSF) family quorum sensing signals to regulate virulence. The biosynthesis and perception of DSF family signals require components of the rpf (regulation of pathogenicity factors) cluster. In this study, we report that RpfB plays an essential role in DSF family signal turnover in X. oryzae pv. oryzae PXO99A. The production of DSF family signals was boosted by deletion of the rpfB gene and was abolished by its overexpression. The RpfC/RpfG-mediated DSF signaling system negatively regulates rpfB expression via the global transcription regulator Clp, whose activity is reversible in the presence of cyclic diguanylate monophosphate. These findings indicate that the DSF family signal turnover system in PXO99A is generally consistent with that in Xanthomonas campestris pv. campestris. Moreover, this study has revealed several specific roles of RpfB in PXO99A. First, the rpfB deletion mutant produced high levels of DSF family signals but reduced extracellular polysaccharide production, extracellular amylase activity, and attenuated pathogenicity. Second, the rpfB/rpfC double-deletion mutant was partially deficient in xanthomonadin production. Taken together, the RpfB-dependent DSF family signal turnover system is a conserved and naturally presenting signal turnover system in Xanthomonas spp., which plays unique roles in X. oryzae pv. oryzae adaptation and pathogenesis.

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Biological Control of Xanthomonas Oryzae pv. Oryzae Causing Rice Bacterial Blight Disease by Streptomyces toxytricini VN08-A-12, Isolated from Soil and Leaf-litter Samples in Vietnam

Biocontrol Science ◽

10.4265/bio.19.103 ◽

2014 ◽

Vol 19 (3) ◽

pp. 103-111 ◽

Cited By ~ 12

Author(s):

DUONG VAN HOP ◽

PHAN THI PHUONG HOA ◽

NGUYEN DUC QUANG ◽

PHAN HUU TON ◽

TRINH HOANG HA ◽

...

Keyword(s):

Biological Control ◽

Leaf Litter ◽

Bacterial Blight ◽

Xanthomonas Oryzae ◽

Rice Bacterial Blight ◽

Bacterial Blight Disease ◽

Blight Disease ◽

Streptomyces Toxytricini

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Identification and Characterization of a Novel Gene, hshB, in Xanthomonas oryzae pv. oryzicola Co-Regulated by Quorum Sensing and clp

Phytopathology ◽

10.1094/phyto-06-11-0169 ◽

2012 ◽

Vol 102 (3) ◽

pp. 252-259 ◽

Cited By ~ 10

Author(s):

Yancun Zhao ◽

Guoliang Qian ◽

Jiaqin Fan ◽

Fangqun Yin ◽

Yijin Zhou ◽

...

Keyword(s):

Quorum Sensing ◽

Extracellular Polysaccharide ◽

Bioinformatic Analysis ◽

Xanthomonas Oryzae ◽

Pcr Analysis ◽

Homologous Gene ◽

Upstream Gene ◽

Novel Gene ◽

Putative Signal Peptide ◽

Diffusible Signal Factor

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.

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Crp-Like Protein Plays Both Positive and Negative Roles in Regulating the Pathogenicity of Bacterial Pustule Pathogen Xanthomonas axonopodis pv. glycines

Phytopathology ◽

10.1094/phyto-07-18-0225-r ◽

2019 ◽

Vol 109 (7) ◽

pp. 1171-1183 ◽

Cited By ~ 3

Author(s):

Wei Guo ◽

Jie Gao ◽

Qingshan Chen ◽

Bojun Ma ◽

Yuan Fang ◽

...

Keyword(s):

Cell Motility ◽

Biofilm Formation ◽

Type Strain ◽

Wild Type Strain ◽

Extracellular Polysaccharide ◽

Polymerase Chain Reaction Analysis ◽

Single Copy ◽

Wild Type ◽

Cell Wall Degrading Enzymes ◽

In The Wild

The global regulator Crp-like protein (Clp) is positively involved in the production of virulence factors in some of the Xanthomonas spp. However, the functional importance of Clp in X. axonopodis pv. glycines has not been investigated previously. Here, we showed that deletion of clp led to significant reduction in the virulence of X. axonopodis pv. glycines in soybean, which was highly correlated with the drastic reductions in carbohydrates utilization, extracellular polysaccharide (EPS) production, biofilm formation, cell motility, and synthesis of cell wall degrading enzymes (CWDEs). These significantly impaired properties in the clp mutant were completely rescued by a single-copy integration of the wild-type clp into the mutant chromosome via homologous recombination. Interestingly, overexpression of clp in the wild-type strain resulted in significant increases in cell motility and synthesis of the CWDEs. To our surprise, significant reductions in carbohydrates utilization, EPS production, biofilm formation, and the protease activity were observed in the wild-type strain overexpressing clp, suggesting that Clp also plays a negative role in these properties. Furthermore, quantitative reverse transcription polymerase chain reaction analysis suggested that clp was positively regulated by the diffusible signal factor-mediated quorum-sensing system and the HrpG/HrpX cascade. Taken together, our results reveal that Clp functions as both activator and repressor in multiple biological processes in X. axonopodis pv. glycines that are essential for its full virulence.

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Variability in Xanthomonas Oryzae Pv. Oryzae, the Incitant of Bacterial Blight Disease of Rice

Journal of Plant Protection Research ◽

10.2478/v10045-009-0003-7 ◽

2009 ◽

Vol 49 (1) ◽

Cited By ~ 1

Author(s):

Debabrata Nayak ◽

Pathirreddy Reddy ◽

Parsuram Nayak

Keyword(s):

Bacterial Blight ◽

Xanthomonas Oryzae ◽

Bacterial Blight Disease ◽

Blight Disease

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Efficacy of bacteriocinogenic strains of Xanthomonas oryzae pv. oryzae on the incidence of bacterial blight disease of rice (Oryza sativa L.)

Canadian Journal of Microbiology ◽

10.1139/m91-131 ◽

1991 ◽

Vol 37 (10) ◽

pp. 764-768 ◽

Cited By ~ 11

Author(s):

N. Sakthivel ◽

T. W. Mew

Keyword(s):

Biological Control ◽

Bacterial Blight ◽

Oryza Sativa L ◽

Disease Incidence ◽

Bacteriocin Production ◽

Xanthomonas Oryzae ◽

Control Treatment ◽

Bacterial Leaf Streak ◽

Blight Disease ◽

Greenhouse Tests

A total of 144 isolates of Xanthomonas oryzae pv. oryzae were screened for bacteriocin production against 30 indicator strains of X. oryzae pv. oryzae. Forty isolates showed broad-spectrum inhibitory activity against 20–27 indicators, presumably because of the production of bacteriocin compounds. The selected isolates were screened for bacteriocin production at 29 °C and tested for virulence on rice differentials. Since all of the isolates were pathogenic, nonpathogenic bacteria were generated through N-methyl-N-nitro-N-nitrosoguanidine mutagenesis and by repeated subculturing. Epiphytic colonization and survival of pathogens and of nonpathogenic bacteriocin producers on rice plants were monitored, using mutants resistant to streptomycin and rifampicin. An improved method of pathogen inoculation was developed and used to evaluate biological control. Treatment with nonpathogenic bacteriocin-producing bacteria resulted in reductions of bacterial blight incidence up to 31–99% in greenhouse tests and 11–73% in the screenhouse. Bacterial leaf streak severity was reduced 4–20% in the greenhouse and disease incidence was reduced 20–39% in the screenhouse. Key words: bacteriocin, biological control, Xanthomonas oryzae pv. oryzae, mutagenesis, rice.

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First method for dissolving zinc thiazole and re-evaluation of its antibacterial properties against rice bacterial blight disease

Phytopathology Research ◽

10.1186/s42483-019-0036-4 ◽

2019 ◽

Vol 1 (1) ◽

Author(s):

Xian Chen ◽

Lan Zhou ◽

Pedro Laborda ◽

Yancun Zhao ◽

Kaihuai Li ◽

...

Keyword(s):

Cell Wall ◽

Bacterial Blight ◽

Antibacterial Properties ◽

Xanthomonas Oryzae ◽

Antibacterial Mechanism ◽

Control Efficacy ◽

Rice Bacterial Blight ◽

Bacterial Blight Disease ◽

Blight Disease ◽

First Time

Abstract Rice bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most destructive diseases in rice-growing regions worldwide. Zinc thiazole is a novel bactericide and has been applied for BB control for 10 years. However, zinc thiazole is highly insoluble in water and in most organic solvents. In this work, we found for the first time that zinc thiazole can be dissolved in dimethyl sulfoxide (DMSO), and the solubility of zinc thiazole in DMSO is more than 20 mg/mL. Dissolved zinc thiazole at 25 μg/mL significantly inhibited the growth of Xoo by 58.81%. Interestingly, zinc thiazole at 25 μg/mL enhanced the cell division and altered the cell wall integrity of Xoo. The application of dissolved zinc thiazole at 100 μg/mL reduced the incidence of rice bacterial blight (BB) by providing 64.71% control efficacy, while zinc thiazole as suspension concentrate (SC) at 100 μg/mL only provided 43.42% control efficacy. Taken together, this study provides for the first time a method for dissolving zinc thiazole, and may help to better understand the antibacterial mechanism of zinc thiazole.

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The Xanthomonas oryzae pv. oryzae PilZ Domain Proteins Function Differentially in Cyclic di-GMP Binding and Regulation of Virulence and Motility

Applied and Environmental Microbiology ◽

10.1128/aem.04044-14 ◽

2015 ◽

Vol 81 (13) ◽

pp. 4358-4367 ◽

Cited By ~ 22

Author(s):

Fenghuan Yang ◽

Fang Tian ◽

Huamin Chen ◽

William Hutchins ◽

Ching-Hong Yang ◽

...

Keyword(s):

Type Iii Secretion ◽

Bacterial Blight ◽

Pathogenic Bacteria ◽

Xanthomonas Oryzae ◽

Wild Type ◽

Binding Motifs ◽

Content Type ◽

Reading Frame ◽

Bacterial Blight Pathogen

ABSTRACTThe PilZ domain proteins have been demonstrated to be one of the major types of receptors mediating cyclic di-GMP (c-di-GMP) signaling pathways in several pathogenic bacteria. However, little is known about the function of PilZ domain proteins in c-di-GMP regulation of virulence in the bacterial blight pathogen of riceXanthomonas oryzaepv. oryzae. Here, the roles of PilZ domain proteins PXO_00049 and PXO_02374 in c-di-GMP binding, regulation of virulence and motility, and subcellular localization were characterized in comparison with PXO_02715, identified previously as an interactor with the c-di-GMP receptor Filp to regulate virulence. The c-di-GMP binding motifs in the PilZ domains were conserved in PXO_00049 and PXO_02374 but were less well conserved in PXO_02715. PXO_00049 and PXO_02374 but not PXO_02715 proteins bound to c-di-GMP with high affinityin vitro, and the R141and R10residues in the PilZ domains of PXO_00049 and PXO_02374, respectively, were crucial for c-di-GMP binding. Gene deletion of PXO_00049 and PXO_02374 resulted in significant increases in virulence andhrpgene transcription, indicating their negative regulation of virulence via type III secretion system expression. All mutants showed significant changes in sliding motility but not exopolysaccharide production and biofilm formation. Intransexpression of the full-length open reading frame (ORF) of each gene in the relevant mutants led to restoration of the phenotype to wild-type levels. Moreover, PXO_00049 and PXO_02374 displayed mainly multisite subcellular localizations, whereas PXO_02715 showed nonpolar distributions in theX. oryzaepv. oryzae cells. Therefore, this study demonstrated the different functions of the PilZ domain proteins in mediation of c-di-GMP regulation of virulence and motility inX. oryzaepv. oryzae.

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