ProA, a Transcriptional Regulator of Fungal Fruiting Body Development, Regulates Leaf Hyphal Network Development in the Epichloë festucae-Lolium Perenne Symbiosis

Mol Microbiol. 2013 Nov;90(3):551-68. doi: 10.1111/mmi.12385. Epub 2013 Sep 18.

Abstract

Transcription factors containing a Zn(II)2 Cys6 binuclear cluster DNA-binding domain are unique to fungi and are key regulators of fungal growth and development. The C6-Zn transcription factor, Pro1, in Sordaria macrospora is crucial for maturation of sexual fruiting bodies. In a forward genetic screen to identify Epichloë festucae symbiosis genes we identified a mutant with an insertion in proA. Plants infected with the proA mutant underwent premature senescence. Hyphae of ΔproA had a proliferative pattern of growth within the leaves of Lolium perenne. Targeted deletion of proA recapitulated this phenotype and introduction of a wild-type gene complemented the mutation. ΔproA was defective in hyphal fusion. qPCR analysis of E. festucae homologues of S. macrospora genes differentially expressed in Δpro1 identified esdC, encoding a glycogen-binding protein, as a target of ProA. Electrophoretic mobility shift assay analysis identified two binding sites for ProA in the intergenic region of esdC and a divergently transcribed gene, EF320. Both esdC and EF320 are highly expressed in a wild-type E. festucae-grass association but downregulated in a proA-mutant association. These results show that ProA is a key regulator of in planta specific growth of E. festucae, and therefore crucial for maintaining a mutualistic symbiotic interaction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Epichloe / classification
  • Epichloe / growth & development
  • Epichloe / metabolism*
  • Epichloe / physiology
  • Fruiting Bodies, Fungal
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Fungal
  • Genes, Fungal
  • Hyphae / growth & development*
  • Lolium / growth & development
  • Lolium / microbiology*
  • Lolium / physiology
  • Mutagenesis, Insertional
  • Plant Leaves / microbiology*
  • Symbiosis

Substances

  • Fungal Proteins