A suppressor/avirulence gene combination in hyaloperonospora arabidopsidis determines race specificity in Arabidopsis thaliana

Alison Woods-Tör, David J. Studholme, Volkan Cevik, Osman Telli, Eric B. Holub, Mahmut Tör

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


The pathosystem of Arabidopsis thaliana and diploid biotrophic oomycete Hyaloperonospora arabidopsidis (Hpa) has been a model for investigating the molecular basis of Flor’s gene-for-gene hypothesis. The isolates Hpa-Noks1 and Hpa-Cala2 are virulent on Arabidopsis accession RMX-A02 whilst an F1 generated from a cross between these two isolates was avirulent. The F2 progeny segregated 3,1 (avirulent, virulent), indicating a single major effect AVR locus in this pathogen. SNP-based linkage mapping confirmed a single AVR locus within a 14kb map interval containing two genes encoding putative effectors. The Hpa-Cala2 allele of one gene, designated H. arabidopsidis cryptic1 (HAC1), encodes a protein with a signal peptide and an RxLR/dEER motif, and triggers a defense response in RMX-A02. The second gene is heterozygous in Hpa-Cala2. One allele, designated Suppressor of HAC1Cala2 (S-HAC1Cala2) encodes a protein with a signal peptide and a dKEE motif with no RxLR motif; the other allele (s-hac1Cala2) encodes a protein with a signal peptide, a dEEE motif and is divergent in sequence from the S-HAC1Cala2 allele. In selfed progeny from Hpa-Cala2, dominant S-HAC1Cala2 allele carrying progeny correlates with virulence in RMX-A02, whereas homozygous recessive s-hac1Cala2 carrying progeny were avirulent. Genetic investigations suggested other heterozygous suppressor loci might exist in the Hpa-Cala2 genome.

Original languageEnglish
Article number265
Pages (from-to)1-16
Number of pages16
JournalFrontiers in Plant Science
Publication statusPublished - 1 Mar 2018


  • Arabidopsis
  • Avirulence inhibitor
  • Downy mildew
  • Effector
  • Heterozygosity
  • Oomycete
  • Suppressor

ASJC Scopus subject areas

  • Plant Science

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