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CWI-MAPKs Regulate the Formation of Hyphopodia Required for Virulence in Ceratocystis fimbriata

Summary

Black rot disease in sweet potatoes is caused by a fungus that uses specialized infection structures called hyphopodia to penetrate plant cells. This study reveals that a cellular signaling pathway involving specific proteins (MAPKs) controls the formation of these infection structures and regulates how the fungus spreads through plants. Understanding this mechanism could help develop new ways to prevent sweet potato infections.

Background

Ceratocystis fimbriata is a destructive fungal pathogen causing black rot disease in sweet potatoes, resulting in significant yield losses worldwide. Previous studies identified the transcription factor CfSwi6 as involved in pathogenicity regulation through the cell wall integrity (CWI) pathway. The infection mechanism of this fungus remains incompletely understood.

Objective

To characterize the upstream CWI-MAPK cascade (CfBck1-CfMkk1-CfSlt2) in C. fimbriata and elucidate how these MAPKs regulate pathogenicity through downstream transcription factor CfSwi6 and infection structure formation.

Results

CWI-MAPK deletion resulted in severe pathogenicity loss and defective hyphopodium formation, a previously unreported infection structure in C. fimbriata. Mutants showed abnormal septin-ring assembly at penetration pegs and reduced ability to penetrate host cells. RNA-seq revealed that CfSlt2 and CfSwi6 co-regulate cellophane surface-induced genes, with PHH50197 and CfHSP30_1 being critical for hyphopodium formation.

Conclusion

The CWI-MAPK-CfSwi6 signaling pathway regulates C. fimbriata virulence through control of septin assembly at infection structures. This work identifies hyphopodia as infection structures and reveals downstream genes mediating pathogenicity, advancing understanding of fungal virulence mechanisms.
  • Published in:Molecular Plant Pathology,
  • Study Type:Experimental Research,
  • Source: PMID: 40624760
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