ATR2Cala2 from Arabidopsis-infecting downy mildew requires 4 TIR-NLR immune receptors for full recognition

Dae Sung Kim, Yufei Li, Hee Kyung Ahn, Alison Woods-Tör, Volkan Cevik, Oliver J. Furzer, Wenbo Ma, Mahmut Tör, Jonathan D.G. Jones

Research output: Contribution to journalArticlepeer-review


Arabidopsis Col-0 RPP2A and RPP2B confer recognition of Arabidopsis downy mildew (Hyaloperonospora arabidopsidis [Hpa]) isolate Cala2, but the identity of the recognized ATR2Cala2 effector was unknown. To reveal ATR2Cala2, an F2 population was generated from a cross between Hpa-Cala2 and Hpa-Noks1. We identified ATR2Cala2 as a non-canonical RxLR-type effector that carries a signal peptide, a dEER motif, and WY domains but no RxLR motif. Recognition of ATR2Cala2 and its effector function were verified by biolistic bombardment, ectopic expression and Hpa infection. ATR2Cala2 is recognized in accession Col-0 but not in Ler-0 in which RPP2A and RPP2B are absent. In ATR2Emoy2 and ATR2Noks1 alleles, a frameshift results in an early stop codon. RPP2A and RPP2B are essential for the recognition of ATR2Cala2. Stable and transient expression of ATR2Cala2 under 35S promoter in Arabidopsis and Nicotiana benthamiana enhances disease susceptibility. Two additional Col-0 TIR-NLR (TNL) genes (RPP2C and RPP2D) adjacent to RPP2A and RPP2B are quantitatively required for full resistance to Hpa-Cala2. We compared RPP2 haplotypes in multiple Arabidopsis accessions and showed that all four genes are present in all ATR2Cala2-recognizing accessions.

Original languageEnglish
JournalNew Phytologist
Early online date14 May 2024
Publication statusE-pub ahead of print - 14 May 2024

Data Availability Statement

All the sequence data used in this study can be found in NCBI (see the Materials and Methods section;;;;;


  • Arabidopsis
  • ATR2
  • Hyaloperonospora arabidopsidis
  • plant immunity
  • RPP2
  • RxLR effector
  • TNL

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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