A wheat tandem kinase activates an NLR to trigger immunity

Abstract

The role of nucleotide-binding leucine-rich repeat (NLR) receptors in plant immunity is well studied, but the function of a class of tandem kinases (TKs) that confer disease resistance in wheat and barley remains unclear. In this study, we show that the SR62 locus is a digenic module encoding the Sr62^TK TK and an NLR (Sr62^NLR), and we identify the corresponding AvrSr62 effector. AvrSr62 binds to the N-terminal kinase 1 of Sr62^TK, triggering displacement of kinase 2, which activates Sr62^NLR. Modeling and mutation analysis indicated that this is mediated by overlapping binding sites (i) on kinase 1 for binding AvrSr62 and kinase 2 and (ii) on kinase 2 for binding kinase 1 and Sr62^NLR. Understanding this two-component resistance complex may help engineering and breeding plants for durable resistance.