Phytophthora infestans isolates lacking class I ipiO variants are virulent on Rpi-blb1 potato

Mol Plant Microbe Interact. 2009 Dec;22(12):1535-45. doi: 10.1094/MPMI-22-12-1535.


A strategy to control the devastating late blight disease is providing potato cultivars with genes that are effective in resistance to a broad spectrum of Phytophthora infestans isolates. Thus far, most late blight resistance (R) genes that were introgressed in potato were quickly defeated. In contrast, the Rpi-blb1 gene originating from Solanum bulbocastanum has performed as an exclusive broad-spectrum R gene for many years. Recently, the RXLR effector family ipiO was identified to contain Avr-blb1. Monitoring the genetic diversity of the ipiO family in a large set of isolates of P. infestans and related species resulted in 16 ipiO variants in three distinct classes. Class I and class II but not class III ipiO variants induce cell death when coinfiltrated with Rpi-blb1 in Nicotiana benthamiana. Class I is highly diverse and is represented in all analyzed P. infestans isolates except two Mexican P. infestans isolates, and these were found virulent on Rpi-blb1 plants. In its C-terminal domain, IPI-O contains a W motif that is essential for triggering Rpi-blb1-mediated cell death and is under positive selection. This study shows that profiling the variation of Avr-blb1 within a P. infestans population is instrumental for predicting the effectiveness of Rpi-blb1-mediated resistance in potato.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Gene Expression Profiling
  • Gene Expression Regulation
  • Genetic Variation
  • Molecular Sequence Data
  • Phylogeny
  • Phytophthora infestans / genetics*
  • Phytophthora infestans / metabolism*
  • Phytophthora infestans / pathogenicity
  • Plant Diseases / microbiology*
  • Solanum tuberosum / microbiology*
  • Virulence


  • Fungal Proteins
  • IpiO1 protein, Phytophthora infestans

Associated data

  • GENBANK/GQ371190
  • GENBANK/GQ371191
  • GENBANK/GQ371192
  • GENBANK/GQ371193
  • GENBANK/GQ371194
  • GENBANK/GQ371195
  • GENBANK/GQ371196
  • GENBANK/GQ371197
  • GENBANK/GQ371198
  • GENBANK/GQ371199
  • GENBANK/GQ371200
  • GENBANK/GQ371201
  • GENBANK/GQ371202
  • GENBANK/GQ371203