Physical mapping of NBS-coding resistance genes to the Me-gene cluster on chromosome P9 reveals markers tightly linked to the N gene for root-knot nematode resistance in pepper

Natural root-knot nematode resistance genes are unique resources to control this major pest in pepper (Capsicum annuum). Although four genes (Me1, Me3, Me7 and N) conferring broad-spectrum resistance were mapped to a cluster in a 28-cm interval on chromosome P9, limited markers targeting this region were available. In the present study, the Me-gene cluster was structurally annotated for resistance genes to develop markers targeting the N gene. As a result, the Me-gene cluster (4.07 Mb in size) was found to contain three resistance gene hotspots. In addition, a SSR maker tightly linked to the N gene (0.8 cM away) was developed for marker-assisted selection in pepper.