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The wxacO gene of Xanthomonas citri ssp. citri encodes a protein with a role in lipopolysaccharide biosynthesis, biofilm formation, stress tolerance and virulence.

ABSTRACT: Xanthomonas citri ssp. citri (Xcc) causes citrus canker, one of the most economically damaging diseases affecting citrus worldwide. Biofilm formation is important for the pathogen to survive epiphytically in planta prior to the induction of canker symptoms. In this study, two EZ-Tn5 transposon mutants of Xcc strain 306, affected in biofilm formation, were isolated; subsequent analyses led to the identification of a novel gene locus XAC3596 (designated as wxacO), encoding a putative transmembrane protein, and the rfbC gene, encoding a truncated O-antigen biosynthesis protein. Sodium dodecylsulphate-polyacrylamide gel electrophoresis revealed that lipopolysaccharide (LPS) biosynthesis was affected in both wxacO and rfbC mutants. The wxacO mutant was impaired in the formation of a structured biofilm on glass or host plant leaves, as shown in confocal laser scanning microscopy analysis of strains containing a plasmid expressing the green fluorescent protein. Both wxacO and rfbC mutants were more sensitive than the wild-type strain to different environmental stresses, and more susceptible to the antimicrobial peptide polymyxin B. The two mutants were attenuated in swimming motility, but not in flagellar formation. The mutants also showed reduced virulence and decreased growth on host leaves when spray inoculated. The affected phenotypes of the wxacO and rfbC mutants were complemented to wild-type levels by the intact wxacO and rfbC genes, respectively. This report identifies a new gene influencing LPS production by Xcc. In addition, our results suggest that a structurally intact LPS is critical for survival in the phyllosphere and for the virulence of Xcc.

SUBMITTER: Li J

PROVIDER: S-EPMC6640450 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

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The wxacO gene of Xanthomonas citri ssp. citri encodes a protein with a role in lipopolysaccharide biosynthesis, biofilm formation, stress tolerance and virulence.

Li Jinyun J Wang Nian N

Molecular plant pathology 20101206 4

Xanthomonas citri ssp. citri (Xcc) causes citrus canker, one of the most economically damaging diseases affecting citrus worldwide. Biofilm formation is important for the pathogen to survive epiphytically in planta prior to the induction of canker symptoms. In this study, two EZ-Tn5 transposon mutants of Xcc strain 306, affected in biofilm formation, were isolated; subsequent analyses led to the identification of a novel gene locus XAC3596 (designated as wxacO), encoding a putative transmembrane ...[more]

PMID: 21453433

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Project description:Citrus canker caused by Xanthomonas citri subsp. citri is one of the most important bacterial diseases of citrus, impacting both plant growth and fruit quality. Identifying and elucidating the roles of genes associated with pathogenesis has aided our understanding of the molecular basis of citrus-bacteria interactions. However, the complex virulence mechanisms of X. citri subsp. citri are still not well understood. In this study, we characterized the role of PhoP in X. citri subsp. citri using a phoP deletion mutant, ΔphoP. Compared with wild-type strain XHG3, ΔphoP showed reduced motility, biofilm formation, as well as decreased production of cellulase, amylase, and polygalacturonase. In addition, the virulence of ΔphoP on citrus leaves was significantly decreased. To further understand the virulence mechanisms of X. citri subsp. citri, high-throughput RNA sequencing technology (RNA-Seq) was used to compare the transcriptomes of the wild-type and mutant strains. Analysis revealed 1017 differentially-expressed genes (DEGs), of which 614 were up-regulated and 403 were down-regulated in ΔphoP. Gene ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggested that the DEGs were enriched in flagellar assembly, two-component systems, histidine metabolism, bacterial chemotaxis, ABC transporters, and bacterial secretion systems. Our results showed that PhoP activates the expression of a large set of virulence genes, including 22 type III secretion system genes and 15 type III secretion system effector genes, as well as several genes involved in chemotaxis, and flagellar and histidine biosynthesis. Two-step reverse-transcription polymerase chain reaction analysis targeting 17 genes was used to validate the RNA-seq data, and confirmed that the expression of all 17 genes, except for that of virB1, decreased significantly. Our results suggest that PhoP interacts with a global signaling network to co-ordinate the expression of multiple virulence factors involved in modification and adaption to the host environment during infection.

Dataset Information

The wxacO gene of Xanthomonas citri ssp. citri encodes a protein with a role in lipopolysaccharide biosynthesis, biofilm formation, stress tolerance and virulence.

Publications

The wxacO gene of Xanthomonas citri ssp. citri encodes a protein with a role in lipopolysaccharide biosynthesis, biofilm formation, stress tolerance and virulence.

Similar Datasets

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