Presence/absence, differential expression and sequence polymorphisms between PiAVR2 and PiAVR2-like in Phytophthora infestans determine virulence on R2 plants

New Phytol. 2011 Aug;191(3):763-76. doi: 10.1111/j.1469-8137.2011.03736.x. Epub 2011 May 3.

Abstract

• A detailed molecular understanding of how oomycete plant pathogens evade disease resistance is essential to inform the deployment of durable resistance (R) genes. • Map-based cloning, transient expression in planta, pathogen transformation and DNA sequence variation across diverse isolates were used to identify and characterize PiAVR2 from potato late blight pathogen Phytophthora infestans. • PiAVR2 is an RXLR-EER effector that is up-regulated during infection, accumulates at the site of haustoria formation, and is recognized inside host cells by potato protein R2. Expression of PiAVR2 in a virulent P. infestans isolate conveys a gain-of-avirulence phenotype, indicating that this is a dominant gene triggering R2-dependent disease resistance. PiAVR2 presence/absence polymorphisms and differential transcription explain virulence on R2 plants. Isolates infecting R2 plants express PiAVR2-like, which evades recognition by R2. PiAVR2 and PiAVR2-like differ in 13 amino acids, eight of which are in the C-terminal effector domain; one or more of these determines recognition by R2. Nevertheless, few polymorphisms were observed within each gene in pathogen isolates, suggesting limited selection pressure for change within PiAVR2 and PiAVR2-like. • Our results direct a search for R genes recognizing PiAVR2-like, which, deployed with R2, may exert strong selection pressure against the P. infestans population.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Chromosome Mapping
  • Cloning, Molecular
  • Gene Expression Regulation
  • Genes, Dominant / genetics
  • Genes, Plant / genetics
  • Molecular Sequence Data
  • Phytophthora infestans / genetics
  • Phytophthora infestans / immunology
  • Phytophthora infestans / pathogenicity*
  • Plant Diseases / immunology*
  • Plant Diseases / microbiology
  • Plant Immunity / genetics
  • Plant Leaves / genetics
  • Plant Leaves / immunology
  • Plant Leaves / microbiology
  • Plant Leaves / physiology
  • Polymorphism, Genetic / genetics*
  • Protein Structure, Tertiary
  • Proteins / genetics
  • Proteins / metabolism*
  • Solanum / genetics
  • Solanum tuberosum / genetics
  • Solanum tuberosum / immunology
  • Solanum tuberosum / microbiology
  • Solanum tuberosum / physiology*
  • Virulence / genetics
  • Virulence Factors / genetics
  • Virulence Factors / metabolism

Substances

  • Proteins
  • Virulence Factors