Selection of stable Brassica napus-Brassica juncea recombinant lines resistant to blackleg (Leptosphaeria maculans). 2. A ‘to and fro’ strategy to localise and characterise interspecific introgressions on the B. napus genome

Abstract

 A new strategy to localise and characterise interspecific introgressions in the genus Brassica is presented. It consists of the localisation of RAPD specific markers from the donor species (B. juncea) by RFLP on a genetic map of the recipient (B. napus) and on the observation of the disappearance of rapeseed markers in recombinant lines. With this method, we localised an interspecific introgression of B. juncea, which confers blackleg resistance at the cotyledon stage in B. napus, on the linkage group DY17 of the previously determined B. napus genetic map. The estimated size of the substituted B. napus fragment was 39 cM, and the resistance gene was introgressed into the rapeseed genome by homologous recombination. The significance of the different strategies used and the implication of these results in breeding programs are discussed.