Evidence for a Second RKN Resistance Gene in Peanut

ABSTRACT Root-knot nematode (RKN), [Meloidogyne arenaria (Neal) Chitwood race 1] can result in highly significant yield losses in peanut (Arachis hypogaea L.) production. Fortunately, very high levels of RKN nematode resistance have been identified and incorporated from wild species into newly developed peanut cultivars. In 2011-12 at Tifton, GA, a field site was artificially inoculated with M. arenaria race 1. A susceptible cultivar was used to uniformly increase the peanut-specific race 1 nematode population during the summer and fall; whereas, hairy vetch (Vicia villosa Roth) was used for the same purpose each winter as a susceptible cover crop. During 2013 and 2014, space-planted F2 and F3 populations from cross combinations involving A. hypogaea susceptible × resistant parental lines derived from ‘COAN’ were evaluated, respectively. Several past inheritance studies had suggested a single dominant gene, Rma, controlled the resistance. However in this study, the occurrence of a second recessive gene (rma2) was also found to be involved in very high peanut RKN resistance. Inheritance data fit a 13:3 genetic model and confirmed an earlier report for two RKN-resistance genes (Rma1 and rma2) found in TxAG-6 and now COAN.