SnTox1, a Parastagonospora nodorum necrotrophic effector, is a dual-function protein that facilitates infection while protecting from wheat-produced chitinases

Zhaohui Liu, Yuanyuan Gao, Yong Min Kim, Justin D. Faris, Weilin L. Shelver, Pierre J.G.M. de Wit, Steven S. Xu, Timothy L. Friesen*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

36 Citations (Scopus)

Abstract

SnTox1 induces programmed cell death and the up-regulation of pathogenesis-related genes including chitinases. Additionally, SnTox1 has structural homology to several plant chitin-binding proteins. Therefore, we evaluated SnTox1 for chitin binding and localization. We transformed an avirulent strain of Parastagonospora nodorum as well as three nonpathogens of wheat (Triticum aestivum), including a necrotrophic pathogen of barley, a hemibiotrophic pathogen of sugar beet and a saprotroph, to evaluate the role of SnTox1 in infection and in protection from wheat chitinases. SnTox1 bound chitin and an SnTox1-green fluorescent fusion protein localized to the mycelial cell wall. Purified SnTox1 induced necrosis in the absence of the pathogen when sprayed on the leaf surface and appeared to remain on the leaf surface while inducing both epidermal and mesophyll cell death. SnTox1 protected the different fungi from chitinase degradation. SnTox1 was sufficient to change the host range of a necrotrophic pathogen but not a hemibiotroph or saprotroph. Collectively, this work shows that SnTox1 probably interacts with a receptor on the outside of the cell to induce cell death to acquire nutrients, but SnTox1 accomplishes a second role in that it protects against one aspect of the defense response, namely the effects of wheat chitinases.

Original languageEnglish
Pages (from-to)1052-1064
JournalNew Phytologist
Volume211
Issue number3
DOIs
Publication statusPublished - 2016

Keywords

  • Parastagonosopora nodorum
  • Chitin
  • Host-selective toxin
  • Necrotroph
  • Necrotrophic effector
  • Programmed cell death (PCD)
  • Wheat (Triticum aestivum) chitinases

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