The diversity of cloned wheat powdery mildew resistance genes and the resistance mechanisms

Abstract Wheat powdery mildew is a destructive disease that significantly impairs wheat yield and quality. The most efficient and sustainable method of controlling powdery mildew ( Pm ) is introducing resistance genes into wheat cultivars. To date, 71 officially named Pm genes have been identified in wheat and its wild relatives. However, some have lost their resistance function due to continuous co-evolution with Bgt . Consequently, there is an ongoing need to discover and deploy more novel Pm genes in wheat breeding programs. This review systematically summarizes all the cloned wheat powdery mildew resistance genes and their underlying mechanisms of resistance. The cloned Pm genes could be categorized into several classes, including singleton nucleotide-binding leucine-rich repeat proteins (NLRs), NLR pairs, NLR with integrated domains (NLR-IDs), tandem kinase proteins (TKPs), tandem kinase with integrated domains (TKP-IDs), TKP-NLR complex, kinase with integrated domains (KD-ID), as well as non-canonical resistance genes. Interestingly, some Pm genes confer resistance to multiple pathogens, probably by recognizing conserved or distinct pathogen effectors. This review offers insights into the evolutionary origins, functional mechanisms, and practical applications of these cloned Pm genes, as well as their implications for genetic engineering and future smart resistance breeding.