These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: The pH signalling transcription factor PacC controls virulence in the plant pathogen Fusarium oxysporum.
    Author: Caracuel Z, Roncero MI, Espeso EA, González-Verdejo CI, García-Maceira FI, Di Pietro A.
    Journal: Mol Microbiol; 2003 May; 48(3):765-79. PubMed ID: 12694620.
    Abstract:
    Gene expression in fungi by ambient pH is regulated via a conserved signalling cascade whose terminal component is the zinc finger transcription factor PacC/Rim1p. We have identified a pacC orthologue in the vascular wilt pathogen Fusarium oxysporum that binds the consensus 5'-GCCAAG-3' sequence and is proteolytically processed in a similar way to PacC from Aspergillus nidulans. pacC transcript levels were elevated in F. oxysporum grown in alkaline conditions and almost undetectable at extreme acidic growth conditions. PacC+/- loss-of-function mutants displayed an acidity-mimicking phenotype resulting in poor growth at alkaline pH, increased acid protease activity and higher transcript levels of acid-expressed polygalacturonase genes. Reintroduction of a functional pacC copy into a pacC+/- mutant restored the wild-type phenotype. Conversely, F. oxysporum merodiploids carrying a dominant activating pacCc allele had increased pacC transcript and protein levels and displayed an alkalinity-mimicking phenotype with reduced acid phosphatase and increased alkaline protease activities. PacC+/- mutants were more virulent than the wild-type strain in root infection assays with tomato plants, whereas pacCc strains were significantly reduced in virulence. We propose that F. oxysporum PacC acts as a negative regulator of virulence to plants, possibly by preventing transcription of acid-expressed genes important for infection.
    [Abstract] [Full Text] [Related] [New Search]