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Marker-assisted introgression of 4 Phytophthora capsici resistance QTL alleles into a bell pepper line: validation of additive and epistatic effects

Thabuis, A., Palloix, A., Servin, B., Daubeze, A.M., Signoret, P., Hospital, F., Lefebvre, V.
Molecular breeding 2004 v.14 no.1 pp. 9-20
Capsicum annuum, sweet peppers, disease resistance, genetic resistance, Phytophthora capsici, plant pathogenic fungi, fungal diseases of plants, plant breeding, quantitative trait loci, alleles, introgression, genetic markers, marker-assisted selection, epistasis, additive gene effects, agronomic traits, chromosome mapping, phenotype
The aim of the present study was to transfer resistance to P. capsici alleles at four quantitative trait loci (QTLs) from a small fruited pepper into a bell pepper recipient line using markers. The marker-assisted selection program was initiated from a doubled-haploid line issued from the mapping population and involved three cycles of marker-assisted backcross (MAB). Two populations, derived by selfing the plants selected after the first selection cycle, were genotyped and evaluated phenotypically for their resistance level. The additive and epistatic effects of the four resistance factors were re-detected and validated in these populations, indicating that introgression of 4 QTLs in this MAB program was successful. A decrease of the effect for the moderate-effect QTLs and of the epistatic interaction was observed. Phenotypic evaluations of horticultural traits were performed on sample of each backcross generation. The results indicated an efficient return to the recipient phenotype using this MAB strategy.