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The Methyltransferase HemK Regulates the Virulence and Nutrient Utilization of the Phytopathogenic Bacterium

Yu Shi1, Xiaobei Yang1, Xiaoxin Ye1

  • 1Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.

International Journal of Molecular Sciences
|April 12, 2022
PubMed

Insights

The HemK protein is essential for citrus canker bacterium Xanthomonas citri subsp. citri (Xcc) virulence. Deleting the hemK gene reduced Xcc

Area of Science:

  • Plant pathology
  • Bacteriology
  • Molecular biology

Background:

  • Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), leads to significant global economic losses.
  • Understanding Xcc virulence mechanisms is crucial for effective disease control.

Purpose of the Study:

  • To investigate the role of the HemK protein in regulating Xcc virulence traits.
  • To elucidate the impact of hemK gene deletion on Xcc phenotypes and gene expression.

Main Methods:

  • Gene deletion of hemK in Xcc jx-6 strain.
  • Phenotypic analysis of the ΔhemK mutant (motility, biofilm, enzyme/polysaccharide production, stress sensitivity).
  • Virulence assays on citrus plants and Nicotiana benthamiana.
  • RNA sequencing to analyze differential gene expression between wild-type and ΔhemK strains.

Main Results:

  • ΔhemK mutant showed decreased motility, biofilm formation, extracellular enzyme and polysaccharide production.
  • The mutant exhibited increased sensitivity to oxidative stress and high temperatures.
  • HemK deletion significantly reduced virulence on citrus plants and compromised hypersensitive response.
  • RNA-seq revealed altered expression of genes involved in secretion systems, chemotaxis, quorum sensing, and nutrient metabolism.

Conclusions:

  • HemK is essential for Xcc virulence.
  • HemK regulates virulence factor synthesis, nutrient utilization, and stress response in Xcc.
  • Targeting HemK could be a strategy for citrus canker management.

Keywords:
HemKRNA-seqXanthomonas citri subsp. citribiofilmexoenzymemotilitystress tolerancevirulence

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