Diversity in receptor‐like kinase genes is a major determinant of quantitative resistance to Fusarium oxysporum f.sp. matthioli

Summary Resistance to wilt fungus Fusarium oxysporum f.sp. matthioli ( FOM ) is a polygenic trait in Arabidopsis thaliana . RFO 3 is one of six quantitative trait loci accounting for the complete resistance of accession Columbia‐0 (Col‐0) and susceptibility of accession Taynuilt‐0 (Ty‐0). We find that Col‐0 and Ty‐0 alleles of RFO 3 are representative of two common variants in wild Arabidopsis accessions, that resistance and susceptibility to FOM are ancestral features of the two variants and that resistance from RFO 3 is unrivalled by other genes in a genome‐wide survey of diversity in accessions. A single receptor‐like kinase ( RLK ) gene in Col‐0 is responsible for the resistance of RFO 3 , although the susceptible Ty‐0 allele codes for two RLK homologs. Expression of RFO 3 is highest in vascular tissue, which F. oxysporum infects, and root‐expressed RFO 3 restricts FOM infection of the vascular system. RFO 3 confers specific resistance to FOM and provides no resistance to two other crucifer‐infecting F. oxysporum pathogens. RFO 3 's identity, expression and specificity suggest that RFO 3 represents diversity in pattern‐recognition receptor ( PRR ) genes. The characteristics of RFO 3 and the previously published RFO 1 suggest that diversity in RLK PRR s is a major determinant of quantitative resistance in wild plant populations.