Diversification and evolution of the avirulence gene AVR-Pita1 in field isolates of Magnaporthe oryzae

Fungal Genet Biol. 2010 Dec;47(12):973-80. doi: 10.1016/j.fgb.2010.08.003. Epub 2010 Aug 16.

Abstract

Rice blast disease is the single most destructive plant disease that threatens stable rice production worldwide. Race-specific resistance to the rice blast pathogen has not been durable and the mechanism by which the resistance is overcome remains largely unknown. Here we report the molecular mechanisms of diversification and the instability of the avirulence gene AVR-Pita1 in field strains of Magnaporthe oryzae interacting with the host resistance gene Pi-ta and triggering race-specific resistance. Two-base-pair insertions resulting in frame-shift mutations and partial and complete deletions of AVR-Pita1 were identified in virulent isolates. Moreover, a total of 38 AVR-Pita1 haplotypes encoding 27 AVR-Pita1 variants were identified among 151 avirulent isolates. Most DNA sequence variation was found to occur in the exon region resulting in amino acid substitution. These findings demonstrate that AVR-Pita1 is under positive selection and mutations of AVR-Pita1 are responsible for defeating race-specific resistance in nature.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Evolution, Molecular*
  • Frameshift Mutation
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism
  • Gene Deletion
  • Host Specificity
  • Magnaporthe / chemistry
  • Magnaporthe / genetics*
  • Magnaporthe / isolation & purification
  • Magnaporthe / pathogenicity
  • Molecular Sequence Data
  • Mutation
  • Oryza / microbiology*
  • Plant Diseases / microbiology*
  • Plant Proteins / genetics
  • Sequence Alignment
  • Virulence

Substances

  • Fungal Proteins
  • Plant Proteins

Associated data

  • GENBANK/FJ842861
  • GENBANK/FJ842862
  • GENBANK/FJ842863
  • GENBANK/FJ842864
  • GENBANK/FJ842865
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