The Spectrum of Diverse Disease-Resistance Genes Cloned and Characterized in the Triticeae Tribe

The Triticeae tribe comprises species representing some of the world's largest food and forage crops, including common wheat, durum, barley, rye, and oat. Crop yields are continuously threatened by various plant diseases and deploying disease resistance (R) genes is a key strategy for protection. More than 70 different Triticeae R gene loci have been cloned, with approximately 60% derived from wild relatives. These R genes belong to diverse protein families, such as receptor kinases (RKs), nucleotide-binding leucine-rich repeat (NLR) immune receptors, tandem kinase proteins, and kinase fusion proteins as well as noncanonical R genes related to membrane, transcription, and detoxification. RKs and NLRs often confer race-specific resistance by recognizing pathogen effectors, whereas noncanonical R genes can provide broad-spectrum resistance. This review provides an overview of the diverse R genes cloned from Triticeae and their evolutionary origins, modes of action, and application in resistance breeding.