Resistance in pea (Pisum sativum) genetic resources to the pea aphid, Acyrthosiphon pisum

The pea aphid (PA), Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae), can cause significant damage to dry and green peas, Pisum sativum L. (Fabaceae). Identifying pea lines with resistance to PA is important to advance available control measures. This research identified lines and putative genes with resistance to PA in the USDA Pisum sativum Collection located in Pullman, WA, USA, consisting of 301 lines collected worldwide. Eight commercial pea cultivars were also evaluated. A cluster analysis based on the mean number of adults, nymphs, and total aphids that developed on lines 10 days after the start of infestation by a single adult aphid per plant identified six clusters. Cluster 2, consisting of 48 lines, had the lowest aphid fecundity of all clusters with 2.1 adults, 7.3 nymphs, and 9.4 total aphids produced on average. 'Lifter' was the most resistant line based on low aphid fecundity. Lifter is a white-flowered green dry pea cultivar that can advance PA resistance in food-type peas. Genotyping by sequencing based on single-nucleotide polymorphisms (SNPs) were used in genome-wide association mapping to locate genes or quantitative trait loci (QTL) linked to PA resistance in which three, nine, and six SNPs were associated with resistance to adult, nymph, and total number of PAs that developed on lines, respectively. Seventeen candidate genes were identified in response to PA resistance. The results can effectively be used in breeding programs to target specific genomic regions with PA resistance and in traditional breeding using resistant lines as parents.