Distinct domains of the AVRPM3A2/F2 avirulence protein from wheat powdery mildew are involved in immune receptor recognition and putative effector function

Kaitlin Elyse McNally, Fabrizio Menardo, Linda Lüthi, Coraline Rosalie Praz, Marion Claudia Müller, Lukas Kunz, Roi Ben-David, Kottakota Chandrasekhar, Amos Dinoor, Christina Cowger, Emily Meyers, Mingfeng Xue, Fangsong Zeng, Shuangjun Gong, Dazhao Yu, Salim Bourras, Beat Keller

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Recognition of the AVRPM3A2/F2 avirulence protein from powdery mildew by the wheat PM3A/F immune receptor induces a hypersensitive response after co-expression in Nicotiana benthamiana. The molecular determinants of this interaction and how they shape natural AvrPm3a2/f2 allelic diversity are unknown. We sequenced the AvrPm3a2/f2 gene in a worldwide collection of 272 mildew isolates. Using the natural polymorphisms of AvrPm3a2/f2 as well as sequence information from related gene family members, we tested 85 single-residue-altered AVRPM3A2/F2 variants with PM3A, PM3F and PM3FL 456P/Y458H (modified for improved signaling) in Nicotiana benthamiana for effects on recognition. An intact AvrPm3a2/f2 gene was found in all analyzed isolates and the protein variant recognized by PM3A/F occurred globally at high frequencies. Single-residue alterations in AVRPM3A2/F2 mostly disrupted, but occasionally enhanced, the recognition response by PM3A, PM3F and PM3FL 456P/Y458H. Residues enhancing hypersensitive responses constituted a protein domain separate from both naturally occurring polymorphisms and positively selected residues of the gene family. These results demonstrate the utility of using gene family sequence diversity to screen residues for their role in recognition. This approach identified a putative interaction surface in AVRPM3A2/F2 not polymorphic in natural alleles. We conclude that molecular mechanisms besides recognition drive AvrPm3a2/f2 diversification.

Original languageEnglish
Pages (from-to)681-695
Number of pages15
JournalNew Phytologist
Volume218
Issue number2
DOIs
StatePublished - 1 Apr 2018
Externally publishedYes

Keywords

  • Blumeria graminis
  • Nicotiana benthamiana
  • Pm3
  • avirulence gene
  • gene synthesis
  • natural diversity
  • site-directed mutagenesis
  • wheat

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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