Evolutionary trade-offs at the Arabidopsis WRR4A resistance locus underpin alternate Albugo candida recognition specificities

Abstract

SummaryThe oomycete Albugo candida causes white rust of Brassicaceae, including vegetable and oilseed crops, and wild relatives such as Arabidopsis thaliana. Novel White Rust Resistance (WRR)-genes from Arabidopsis enable new insights into plant/parasite co-evolution. WRR4A from Arabidopsis accession Col-0 provides resistance to many but not all white rust races, and encodes a nucleotide-binding (NB), leucine-rich repeat (LRR) (NLR) immune receptor protein. Col-0 WRR4A resistance is broken by a Col-0-virulent isolate of A. candida race 4 (AcEx1). We identified an allele of WRR4A in Arabidopsis accession Oy-0 and other accessions that confers full resistance to AcEx1. WRR4AOy-0 carries a C-terminal extension required for recognition of AcEx1, but reduces recognition of several effectors recognized by the WRR4ACol-0 allele. WRR4AOy-0 confers full resistance to AcEx1 when expressed as a transgene in the oilseed crop Camelina sativa.SignificanceA C-terminal extension in an allele of the Arabidopsis resistance-protein WRR4A changes effector recognition specificity, enabling the WRR4AOy-0 allele to confer immunity to Albugo candida races that overcome the WRR4ACol-0 allele. This resistance can be transferred to the oil-producing crop Camelina sativa.Graphical abstract