A major QTL conferring downy mildew resistance in ‘Couve Algarvia’ (Brassica oleracea var. tronchuda) is located on chromosome 8

P.S. Coelho, J.D. Carlier, A.A. Monteiro, J.M. Leitão
Downy mildew, elicited by the oomycete Hyaloperonospora brassicae (Gäumann), ranks among the most destructive foliar diseases of Brassica crops, very negatively affecting the quality and quantity of the final product. The implementation of sustainable and ecologically responsible agriculture, abiding by the consecutively adopted strict legislation concerning the registration and use of pesticides and other pollutant chemicals, presupposes the continuous development of novel disease resistant cultivars that require the continuous identification and introduction of novel sources of genetic resistance. While, in Brassica oleracea L., downy mildew resistance at the cotyledon and adult plant stages are weakly correlated, ‘Couve Algarvia’ (Brassica oleracea var. tronchuda Bailey) exhibits strong resistance to downy mildew at both developmental stages. Aiming at the identification of the genetic features that confer this downy mildew resistance, an F2 mapping population of 133 plants was generated by crossing an S3 line of this resistant genotype with a susceptible rapid-cycling double-haploid line. An accurate genotypic analysis of the downy mildew resistance was carried out for all F2 plants, assessing the plant/pathogen interaction on an average number of 11.6 plants per F2:3 progeny. Bulked segregant analysis (BSA) was performed using large numbers of RAPD, ISSR, microsatellites (SSR) and BAC-end based markers. A major QTL, which we designated as PpALG1, that explained 40.96% of the observed plant/pathogen phenotypic variance, was located in a genome region of chromosome 8, where another downy mildew resistance gene (Pp523) was previously located.
Coelho, P.S., Carlier, J.D., Monteiro, A.A. and Leitão, J.M. (2023). A major QTL conferring downy mildew resistance in ‘Couve Algarvia’ (Brassica oleracea var. tronchuda) is located on chromosome 8. Acta Hortic. 1362, 289-296
DOI: 10.17660/ActaHortic.2023.1362.39
plant diseases, Hyaloperonospora, plant disease resistance, genetic mapping, plant QTL mapping

Acta Horticulturae