Plant genetic background increasing the efficiency and durability of major resistance genes to root knot nematodes can be resolved into a few resistance QTLs

With the banning of most chemical nematicides, the control of root knot nematodes (RKNs) in vegetable crops is mainly based on the deployment of single-major resistance genes (R-genes). However, these genes are rare and their efficiency is threatened by RKNs capacities of adaptation. ln pepper, several dominant R-genes are efficient against RKNs, but their efficiency and durability were shown to be increased in partially resistant genetic background. A QTL analysis was performed in such a genetic background, using a F2:3population from the cross between Yolo Wonder, a partially resistant to resistant accession depending on RKN species, and Doux Long des Landes, a susceptible one. The genetic linkage map was constructed from 130 F2 individuals and the 130 F3 families were tested forresistance to the three main RKNs species, M incognita, M arenaria and Mjavanica. Four new major QTLs were mapped into two clusters. The cluster on chromosome Pl includes three tightly linked QTLs with specifie effects against each RKN species. The fourth QTL, specifie of resistance to M javanica, mapped on the pepper chromosome P9, which is known to carry multiple NBS-LRR repeats with major resistance genes to nematodes and other pathogens. The newly discovered cluster on chromosome Pl, displays a broad spectrum of action with major additive effects on resistance. Therefore, it provides innovative potential for breeding new cultivars or rootstocks combining quantitative resistance and major resistance genes and increasing the efficiency as weil as the durability ofRKNs genetic control.