A small secreted protein in Zymoseptoria tritici is responsible for avirulence on wheat cultivars carrying the Stb6 resistance gene - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2017

A small secreted protein in Zymoseptoria tritici is responsible for avirulence on wheat cultivars carrying the Stb6 resistance gene

Résumé

Zymoseptoria tritici is the causal agent of Septoria tritici blotch (STB), a major pathogen of wheat globally and the most damaging pathogen of wheat in Europe. The Z. tritici infection cycle includes an extended asymptomatic phase characterized by slow apoplastic growth followed by a switch to necrotrophy that coincides with the onset of plant cell death. Gene-for-gene (GFG) interactions between this apoplastic pathogen and resistant wheat cultivars have been postulated for many years, but until now none of the genes involved in this interaction were identified. We identified AvrStb6 by combining QTL mapping based on a cross between two Swiss strains with a genome-wide association study (GWAS) using a natural population of ~100 strains coming from France. We functionally validated AvrStb6 using ectopic transformations. AvrStb6 encodes a small, cysteine-rich, secreted protein, with features of fungal effector proteins, which produces an avirulence phenotype on wheat cultivars carrying the Stb6 resistance gene. AvrStb6 shows peak of expression during the transition to the necrotrophic phase suggesting that the protein may act as a necrotrophic effector in susceptible cultivars. We found 16 non-synonymous SNPs among the tested strains, indicating that AvrStb6 is evolving very rapidly. By analyzing the finished genomes of both parental strains used to establish the cross, we found that AvrStb6 is located in a highly polymorphic subtelomeric region and is surrounded by transposable elements. This genomic environment may facilitate the rapid evolution of AvrStb6 and enable Z. tritici to rapidly adapt to overcome Stb6 resistance. AvrStb6 is the first avirulence gene to be functionally validated in Z. tritici, contributing to our understanding of avirulence in apoplastic pathogens and the mechanisms of GFG interactions between Z. tritici and wheat.
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Dates et versions

hal-01530826 , version 1 (31-05-2017)

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Paternité - Partage selon les Conditions Initiales

Identifiants

  • HAL Id : hal-01530826 , version 1
  • PRODINRA : 390411

Citer

Ziming Zhong, Thierry Marcel, Clemence Plissonneau, Bruce A. Mcdonald, Daniel Croll, et al.. A small secreted protein in Zymoseptoria tritici is responsible for avirulence on wheat cultivars carrying the Stb6 resistance gene. 29. Fungal genetics conference Asilomar 17, Mar 2017, Pacific Grove CA, United States. p.246. ⟨hal-01530826⟩
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