Aphid resistance in Capsicum maps to a locus containing LRR-RLK gene analogues

Key message A QTL for aphid resistance on pepper chromosome 2 was identified and validated. This QTL affects aphid survival and reproduction, and was fine mapped to a locus containing LRR-RLK analogues. Myzus persicae is one of the most threatening insect pests that adversely affects pepper ( Capsicum ) cultivation. Resistance to aphids was previously identified in Capsicum baccatum . This study aimed at elucidating the genetics of aphid resistance in C. baccatum . A QTL analysis was carried out for M. persicae resistance in an F 2 population derived from an intraspecific cross between a highly resistant plant and a susceptible plant. Survival and reproduction were used as resistance parameters. Interval mapping detected two QTLs affecting aphid survival ( Rmpas-1 ) and reproduction ( Rmprp-1 ), respectively, both localized in the same area and sharing the same top marker on chromosome 2. Use of this marker as co-factor in multiple-QTL mapping analysis revealed a second, minor QTL ( Rmprp-2 ) only affecting aphid reproduction, on chromosome 4. Fine mapping confirmed the effects of Rmpas-1 and Rmprp-1 and narrowed the major QTL Rmprp-1 down to a genomic region of 96 kb which is predicted to encode four analogues of resistance genes of the receptor-like kinase family containing a leucine-rich repeat domain (LRR-RLKs). This work provides not only initial information for breeding aphid-resistant pepper varieties, but also forms the basis for future molecular analysis of gene(s) involved in aphid resistance.