The rsmA-like gene rsmAXoo of Xanthomonas oryzae pv. oryzae regulates bacterial virulence and production of 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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Identification of non-TAL effectors in Xanthomonas oryzae pv. oryzae Chinese strain 13751 and analysis of their role in the bacterial virulence

World Journal of Microbiology and Biotechnology ◽

10.1007/s11274-012-1229-5 ◽

2013 ◽

Vol 29 (4) ◽

pp. 733-744 ◽

Cited By ~ 11

Author(s):

Shuai Zhao ◽

Wei-Lan Mo ◽

Fan Wu ◽

Wei Tang ◽

Ji-Liang Tang ◽

...

Keyword(s):

Bacterial Virulence ◽

Xanthomonas Oryzae ◽

Chinese Strain ◽

Tal Effectors

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The diffusible signal factor synthase, RpfF, in Xanthomonas oryzae pv. oryzae is required for the maintenance of membrane integrity and virulence

Molecular Plant Pathology ◽

10.1111/mpp.13148 ◽

2021 ◽

Author(s):

Prashantee Singh ◽

Raj Kumar Verma ◽

Subhadeep Chatterjee

Keyword(s):

Membrane Integrity ◽

Xanthomonas Oryzae ◽

Diffusible Signal Factor

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Identification of c-di-GMP Signaling Components in Xanthomonas oryzae and Their Orthologs in Xanthomonads Involved in Regulation of Bacterial Virulence Expression

Frontiers in Microbiology ◽

10.3389/fmicb.2019.01402 ◽

2019 ◽

Vol 10 ◽

Cited By ~ 1

Author(s):

Fenghuan Yang ◽

Dingrong Xue ◽

Fang Tian ◽

William Hutchins ◽

Ching-Hong Yang ◽

...

Keyword(s):

Bacterial Virulence ◽

Xanthomonas Oryzae ◽

Signaling Components

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

Microbiology ◽

10.1099/mic.0.028910-0 ◽

2009 ◽

Vol 155 (9) ◽

pp. 3033-3044 ◽

Cited By ~ 31

Author(s):

Jia-Xun Feng ◽

Zhi-Zhong Song ◽

Cheng-Jie Duan ◽

Shuai Zhao ◽

Ying-Qiao Wu ◽

...

Keyword(s):

Bacterial Blight ◽

Extracellular Polysaccharide ◽

Xanthomonas Oryzae ◽

Northern Hybridization ◽

Wild Type ◽

Glycogen Accumulation ◽

Diffusible Signal Factor ◽

In The Wild ◽

Oil Plant ◽

Blight Disease

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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Atypical Regulation of Virulence-Associated Functions by a Diffusible Signal Factor in Xanthomonas oryzae pv. oryzae

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-11-11-0285-r ◽

2012 ◽

Vol 25 (6) ◽

pp. 789-801 ◽

Cited By ~ 41

Author(s):

Rikky Rai ◽

Manish Ranjan ◽

Binod B. Pradhan ◽

Subhadeep Chatterjee

Keyword(s):

Biofilm Formation ◽

Bacterial Blight ◽

Hydrolytic Enzymes ◽

Xanthomonas Oryzae ◽

Enzymatic Assays ◽

Expression Of Genes ◽

Associated Functions ◽

Diffusible Signal Factor ◽

Bacterial Blight Pathogen ◽

Transcriptional Changes

In Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, a secreted fatty acid signaling molecule known as diffusible signal factor (DSF) is required for virulence and growth on low-iron medium. To identify other virulence-associated traits that are regulated by DSF in this pathogen, we have performed microarray analysis of transcriptional changes between the wild type and DSF-deficient mutants of X. oryzae pv. oryzae. Expression of genes that encode secreted hydrolytic enzymes, motility, and chemotaxis functions are negatively regulated by DSF while functions involved in adhesion and biofilm formation are positively regulated. Enzymatic assays for hydrolytic enzymes as well as assays for chemotaxis, motility, attachment, and biofilm formation corroborate these findings. These results demonstrate that, in X. oryzae pv. oryzae, DSF-mediated cell-to-cell signaling coordinates transition from solitary to biofilm lifestyle by promoting expression of attachment functions and negatively regulating expression of motility functions. This is in contrast to X. campestris pv. campestris, a pathogen of crucifers, wherein the DSF system positively regulates motility functions and negatively regulates biofilm formation. These results indicate that virulence-associated functions can be regulated in a completely contrasting fashion by the same signaling system in very closely related bacteria.

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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

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-12-13-0371-r ◽

2014 ◽

Vol 27 (6) ◽

pp. 578-589 ◽

Cited By ~ 37

Author(s):

Fenghuan Yang ◽

Fang Tian ◽

Xiaotong Li ◽

Susu Fan ◽

Huamin Chen ◽

...

Keyword(s):

Gene Expression ◽

Pathogenic Bacteria ◽

In Silico Analysis ◽

Bacterial Virulence ◽

Xanthomonas Oryzae ◽

Glutathione S Transferase ◽

Ggdef Domain ◽

Domain Protein ◽

Silico Analysis

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. Both in silico analysis and enzyme assays indicated that the GGDEF and EAL domains of Filp were degenerate and enzymatically inactive. However, Filp bound to c-di-GMP efficiently within the EAL domain, where Q477, E653, and F654 residues were crucial for the binding. Deletion of the filp gene in X. oryzae pv. oryzae resulted in attenuated virulence in rice and reduced type III secretion system (T3SS) gene expression. Complementation analysis with different truncated proteins indicated that REC, PAS, and EAL domains but not the GGDEF domain were required for the full activity of Filp in vivo. In addition, a PilZ-domain protein (PXO_02715) was identified as a Filp interactor by yeast two-hybrid and glutathione-S-transferase pull-down assays. Deletion of the PXO_02715 gene demonstrated changes in bacterial virulence and T3SS gene expression similar to Δfilp. Moreover, both mutants were impaired in their ability to induce hypersensitive response in nonhost plants. Thus, we concluded that Filp was a novel c-di-GMP receptor of X. oryzae pv. oryzae, and its function to regulate bacterial virulence expression might be via the interaction with PXO_02715.

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