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Abstract

The oomycete pathogen Hyaloperonospora arabidopsidis specifically infects a single host, Arabidopsis thaliana, pointing to a strong co-evolutionary relationship. This pathogen secretes effectors into the host cells that are able to manipulate the plant immune network, promoting successful infection. When recognized by the host immune system, though, they confer host resistance in the form of effector-triggered immunity (Coates & Beynon, 2010; Polonio et al., 2020). We have collected and whole-genome sequenced over one hundred new pathogen isolates from much of the European range of Arabidopsis thaliana and discovered allelic diversity within the pathogen effector genes. At the ATR1 locus, we found over 50 alleles, at least some of which might be recognized by different alleles at the host RPP1 locus. RPP1 allelic variation has been deduced from long-read genome >assemblies of A. thaliana accessions. Ongoing experiments seek to understand the functional differences of ATR1 variants on recognition by the host, investigating both different Arabidopsis thaliana accessions and heterologous expression in combination with RPP1 alleles.