Validation of resistance to root‐knot nematode incorporated in peanut from the wild relative Arachis stenosperma

Peanut (Arachis hypogaea L.) root-knot nematode (PRKN) Meloidogyne arenaria is a very destructive pathogen to which most peanut cultivars are highly susceptible. Current peanut cultivars rely on a single locus for PRKN resistance incorporated from the wild relative A. cardenasii Krapov. & W.C. Greg., that could be overcome as a result of the emergence of new nematode populations. Thus, new sources of resistance are continually needed. A new and strong resistance has been found in the wild diploid relative, A. stenosperma Krapov. & W.C. Greg. Arachis stenosperma-derived quantitative trait loci (QTL) were described on chromosomes A02 and A09 and reduced nematode development by up to 98.2%. In order to validate these resistance segments, this study screened for PRKN resistance in BC2F1 lines and correlated with molecular genotypes. Here, six BC(2)F(1)s carrying chromosome introgressions in A02 and/or A09, showed strong resistance while one line was susceptible. Both phenotype and genotype data allowed us to validate and delineate the chromosomal segments in chromosomes A02 and A09 to similar to 8.5Mbp and similar to 6.5Mbp regions on the bottom of each, respectively. Within the QTL on A02 and top middle of both chromosomes A02 and A09 there are R-gene clusters, often implicated in pathogen resistance. We have provided validation of these key resistance QTL that can be used to inform breeding via marker selection and insights into the functional basis of resistance provided by the wild peanut relative A. stenosperma.