RESISTANCE TO LEVEILLULA-TAURICA IN PEPPER (CAPSICUM-ANNUUM) IS OLIGOGENICALLY CONTROLLED AND STABLE IN MEDITERRANEAN REGIONS

The resistance to Leveillula taurica from an african pepper line H3 (Capsicum annuum) was evaluated and analysed, using the androgenetic haplodiploid progeny from an F-1 hybrid between H3 and a susceptible line. Tests were performed in natural infection conditions in two locations (France and Sicily). Stable behaviour of the parental and haplodiploid lines was observed in both locations, confirming the high level and stability of this resistance source in Mediterranean countries. Heritability of resistance was high and genetic analysis suggested that it is under oligogenic control. However, the number of genetic factors involved in resistance depended on infection conditions: two or three genetic factors with additive and partial dominance effects appear sufficient to confer resistance at the beginning of the epidemic or in weak infection conditions. However, additional genes are necessary to slow down further disease progress and secondary infections and at least five genetic factors are necessary to confer resistance in severe infection, In this case, both additive and epistatic effects are significant. The transfer of this resistance into cultivars will require the use of artificial inoculation procedures to control the severity of the test.