Characterisation of virulence in populations of Meloidogyne chitwoodi and evidence for a resistance gene in pepper Capsicum annuum L. line PM 217

Doubled haploid lines of pepper from the F I hybrid of PM 217 x Yolo Wonder were tested for their resistance to different populations of Meloidogyne chitwoodi. PM 217 has the Me1 gene for resistance to Meloidogyne incognita, M. arenaria, M. javanica and Me2 gene for resistance to M. hispanica. With two European populations a clear segregation was observed. The necrotic reactions and the resistant : susceptible segregation of I : I suggested the occurrence of a major gene, different from but close to Me1. With another European population of M. chinwoodi and with M. fallax, no resistance was observed. Two American and two southern European M. chitwoodi populations were totally avirulent to the two pepper parents. These results demonstrate the existence of great polymorphism in M. chitwoodi populations and of a major gene in pepper controlling a specific resistance against some populations.