Over 230 rust resistance genes have been genetically defined across the wheat genome. Introgression from wheat wild relatives accounts for 44% of these genes. A myriad of expression patterns characterize resistance phenotypes, including a blurring of developmental stages, some specific to adult plants and in other instances, suppression of functional resistance genes. Genes encoding classical plant immune receptors and an increasing number of kinase fusions control seedling/all stage resistance. Additional non-canonical resistance genes are being uncovered as more targets are explored. A wide spectrum of resistance gene durability is also evident, spanning short-lived (<3years) genes to those deployed over 60-100 years without increased pathogen virulence. Interestingly, a subset of the genes involved in adult plant resistance (APR) are unrelated to immune receptors and represent unique classes of resistance genes. Anion channel functionality is emerging as a defining feature of the durable types of APR. Some of these APR genes confer partial resistance to multiple pathogen species and transgenic studies have shown that they function in other crops beyond the Triticeae and provide resistance against pathogen species that are un-adapted to wheat. While the intricacies of multi-pathogen APR remain poorly understood, APR genes are critical for durable disease resistance in global wheat improvement
