Targeted disruption of a fungal G-protein beta subunit gene results in increased vegetative growth but reduced virulence

Mol Plant Microbe Interact. 1997 Nov;10(8):984-93. doi: 10.1094/MPMI.1997.10.8.984.

Abstract

Targeted disruption of two G-protein alpha subunit genes in the chestnut blight fungus Cryphonectria parasitica revealed roles for the Gi alpha subunit CPG-1 in fungal reproduction, virulence, and vegetative growth. A second G alpha subunit, CPG-2, was found to be dispensable for these functions. We now report the cloning and targeted disruption of a C. parasitica G-protein beta subunit gene. The deduced amino acid sequence encoded by this gene, designated cpgb-1, was found to share 66.2, 65.9, and 66.7% amino acid identity with G beta homologues from human, Drosophila, and Dictyostelium origins, respectively, but only 39.7% identity with the Saccharomyces cerevisiae G beta homologue STE4 product. Low stringency Southern hybridization failed to detect any related G beta subunit genes in C. parasitica. Targeted disruption of cpgb-1 resulted in several of the changes previously reported to accompany disruption of the C. parasitica Gi alpha subunit gene cpg-1. These included very significant reductions in pigmentation, asexual sporulation, and virulence. In contrast to results obtained for Gi alpha gene disruption, the reduction in virulence resulting from the disruption of a G beta gene was accompanied by increased, rather than decreased, vegetative growth on synthetic medium. The relevance of these results to mechanisms of fungal virulence is considered.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Ascomycota / genetics*
  • Ascomycota / growth & development
  • Ascomycota / pathogenicity
  • Base Sequence
  • Cloning, Molecular
  • GTP-Binding Proteins / genetics*
  • Genes, Fungal*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Nuts / microbiology
  • Plant Diseases / microbiology*
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Trees / microbiology
  • Virulence / genetics

Substances

  • GTP-Binding Proteins

Associated data

  • GENBANK/U95139