Coordinated function of paired NLRs confers Yr84-mediated stripe rust resistance in wheat

Abstract

Cloning of resistance genes expands our understanding of their function and facilitates their deployment in breeding. Here we report the cloning of two genes from wild emmer wheat (Triticum turgidum ssp. dicoccoides) underlying Yr84-mediated stripe rust resistance using a combination of fine mapping, long-read sequencing and mutation-induced functional validation. In contrast to all previously cloned stripe rust genes, the incompletely dominant Yr84 phenotype is conferred through the coordinated function of paired nucleotide-binding leucine-rich repeat (NLR) genes CNL and NL. We reason that based on their genomic organization, annotation, expression profiles and predicted protein structure, CNL functions as a sensor NLR, responsible for effector recognition, and NL acts as a helper NLR, initiating downstream resistance cascades. Both the CNL and NL lack an integrated domain(s) previously implicated in effector recognition by paired NLRs; therefore, these findings contribute insights into the structure and molecular mechanisms of the function of plant paired NLRs. The study reports the cloning of paired NLR genes CNL and NL from wild emmer wheat and demonstrates their coordinated function in conferring Yr84-mediated wheat stripe rust resistance.