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The pH-Responsive Transcription Factor PacC Governs Pathogenicity and Ochratoxin A Biosynthesis in Aspergillus

Omer Barda1, Uriel Maor1,2, Sudharsan Sadhasivam1

  • 1Institute of Postharvest and Food Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel.

Frontiers in Microbiology
|March 3, 2020
PubMed

Insights

PacC-mediated pH signaling is crucial for Aspergillus carbonarius pathogenicity. Deleting the PacC gene impairs fungal growth, toxin production, and virulence, highlighting its role in fungal infection.

Area of Science:

  • Mycology
  • Plant Pathology
  • Molecular Biology

Background:

  • Pathogenic fungi require environmental pH response for host colonization, virulence, and toxin production.
  • Aspergillus carbonarius is a mycotoxigenic pathogen known to colonize plants and produce ochratoxin A (OTA).

Purpose of the Study:

  • To characterize the functions of PacC-mediated pH signaling in Aspergillus carbonarius.
  • To investigate the role of PacC in A. carbonarius pathogenicity, ochratoxin A biosynthesis, and host-pathogen interactions.

Main Methods:

  • Construction and analysis of a pacC gene knockout mutant (ΔAcpacC) in A. carbonarius.
  • Phenotypic characterization of the mutant, including growth, sporulation, conidial germination, acid production, OTA production, and virulence assays.
  • Reintroduction of the pacC gene to confirm the observed phenotypes.

Main Results:

  • The ΔAcpacC mutant exhibited an acidity-mimicking phenotype, with impaired growth at neutral/alkaline pH, reduced sporulation, and decreased conidial germination.
  • The mutant showed diminished gluconic and citric acid production, leading to inefficient media acidification.
  • Loss of AcpacC completely inhibited OTA production at pH 7.0 and resulted in attenuated virulence towards grapes and nectarine fruits.

Conclusions:

  • PacC plays a critical role in Aspergillus carbonarius by regulating pH signaling pathways.
  • PacC is essential for ochratoxin A biosynthesis and fungal pathogenicity, controlling genes involved in secondary metabolism and infection processes.
Keywords:
Aspergillus carbonariusOTA biosynthesisPacCpH regulationpost-harvest disease

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