Pyramiding resistance genes for aphanomyces root rot in peas

Abstract

Dry pea is an important legume crop due to its protein content, nitrogen fixation ability, and value to crop rotation practices. These aspects contribute to both human and animal consumption. Pea cultivation is challenged from both abiotic and biotic stress. Soil-borne root rot pathogens lead to significant yield losses, up to 70%. Aphanomyces root rot (ARR) (caused by Aphanomyces euteiches Dreches) is one of the most destructive pea oomycete pathogens capable of attacking pea plants at any stage of development. Common symptoms include root decay, chlorosis, and wilting, particularly in wet soil conditions. Oospores are sexual spores produced by pathogens that can remain in the soil for many years, contributing to pathogen persistence. Standard practices such as seed treatment and other cultural practices have proven ineffective against this pathogen. Two major quantitative trait loci (QTL) Ae.Ps4.5 and Ae.Ps7.6 have been reported in previous studies. This research aims to pyramid quantitative trait loci Ae.Ps4.5 and Ae.Ps7.6 to increase ARR resistance in pea genotypes through marker-assisted selection. The derived lines with multiple QTL were evaluated using artificial inoculation methods in controlled environments. The first approach was to characterize reportedly resistant germplasm for reaction to ARR through rigorous pure culture screening. Subsequently generating molecular markers to facilitate introgression of ARR resistance QTLs into adapted genetic backgrounds as germplasm or cultivars suitable for cultivation in Montana. This study illustrates integration of multiple resistance genes minimizes the risk of pathogen adaptation and enables the development of cultivars with broad-spectrum resistance against ARR. Development of resistant varieties is crucial for ensuring sustainable pea production. This study demonstrates the application of marker assisted selection for pyramiding genes for ARR resistance.