Genetic analysis and molecular mapping of genes resistant to Didymella pisi in peas

Abstract

Ascochyta Blight, a seed-borne and foliar disease of peas poses a significant threat to its production. The disease is caused by four necrotrophic fungal pathogens known as the Ascochyta complex, including Didymella pisi, D. pinodes, D. pinodella, and Phoma koolunga, and D. pisi is the most prevalent species in Montana, causes up to 75% yield loss. Current disease management strategies include crop rotation, fungicides, and limited use of resistant cultivars due to the lack of available resistance resources for breeding. From a high-throughput screening, we identified the cultivar "Fallon" was immune to D. pisi. Two mapping populations derived from crosses between Fallon and the susceptible cultivar, "Stirling", have been developed. Through progeny testing and genetic analysis, two recessive genes in Fallon are required to confer resistance against D. pisi isolate '22-P2033', and only one recessive gene is required for resistance against D. pisi isolate '10728'. The resistance genes required for D. pisi isolate '22-P2033' were mapped on chromosomes I and V, and the resistance gene required for resistance against D. pisi isolate '10728' was mapped on chromosome V. Additional polymorphisms have been identified for future marker development to assist the selection of the resistance gene. The research facilitates resistance breeding to Ascochyta Blight and paves the path for future marker development.