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 (C apsicum annuum) was evaluated and analysed, using the androgenetic hap lodiploid progeny from an F-1 hybrid between H3 and a susceptible line . Tests were performed in natural infection conditions in two location s (France and Sicily). Stable behaviour of the parental and haplodiplo id lines was observed in both locations, confirming the high level and stability of this resistance source in Mediterranean countries. Herit ability of resistance was high and genetic analysis suggested that it is under oligogenic control. However, the number of genetic factors in volved in resistance depended on infection conditions: two or three ge netic factors with additive and partial dominance effects appear suffi cient 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 f ive genetic factors are necessary to confer resistance in severe infec tion, In this case, both additive and epistatic effects are significan t. The transfer of this resistance into cultivars will require the use of artificial inoculation procedures to control the severity of the t est.