Elite agronomic performance in cultivated peanut (Arachis hypogaea) with strong resistance to root-knot nematode (Meloidogyne spp.) introgressed from Arachis stenosperma

Root-knot nematode (RKN) is a major pathogen of cultivated peanut, Arachis hypogaea, that can incur losses of >50% yield. Currently, one source of strong RKN resistance has been introduced into cultivated peanut through introgression from the wild peanut relative A. cardenasii. This resistance has been incorporated into several cultivars and is the only currently available genetic resistance in commercial cultivars; however, growers still favor susceptible cultivars for their superior yield stability and potential. A new source of resistance from the wild species Arachis stenosperma has been introduced to cultivated peanut by backcrossing, conferring near-total immunity to RKN reproduction and galling under controlled conditions. In field trials with and without nematode pressure, we tested the RKN resistance and agronomic performance of a selection of these lines. We found reductions in RKN galling and egg production, averaging 98.6% and 99.1%, respectively, consistent with previous studies. Backcrossed lines with or without the RKN resistance locus were similar or superior to popular peanut cultivars in seedling vigor and stand visual ratings. Under heavy nematode pressure, the resistant backcrossed lines yielded an average of 75% more than popular susceptible cultivars. Without nematode pressure, the yield of the backcrossed lines was statistically indistinguishable from the cultivars. Analysis of agronomically important traits including pod constriction and 100-seed weight showed no significant difference between nematode-resistant lines and the popular cultivar checks. This work shows the potential for peanut cultivars to incorporate RKN resistance from A. stenosperma without losses in agronomic fitness or yield.