Field Test Results Versus Marker Assisted Selection for Root-Knot Nematode Resistance in Peanut

Abstract

ABSTRACT A common set of 12 advanced Georgia peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) breeding lines that were derived from ‘COAN’ cross combinations were compared with three check cultivars for root-knot nematode (RKN) [Meloidogyne arenaria (Neal) Chitwood race 1] resistance. These 15 genotypes were grown in RKN populated field tests using a randomized complete block design with three replications for two years (2011 and 2012). Two molecular markers (SCAR 197/909 and SSR-GM565) used for marker assisted selection (MAS) did not agree with low gall ratings and high pod yield for four out of the 15 genotypes (26.7%). The results were the same each year with the same four field RKN-resistant genotypes being incorrectly identified as susceptible (false negatives) by both markers. Reciprocal cross combinations involving field resistant parents showed one-gene difference between MAS resistant × MAS susceptible in F1 and F2 populations. The lack of accuracy differentiating resistant RKN breeding lines when using these two markers was attributed to either recombination between the resistant gene RMA and these two markers, or the possible identification of a second unlinked nematode resistant gene. Regardless, more tightly-linked molecular markers are needed for RKN-resistance in future MAS breeding programs.