Development of molecular markers linked to the Leptosphaeria maculans resistance gene Rlm6 and inheritance of SCAR and CAPS markers in Brassica napusxBrassica juncea interspecific hybrids

摘要

Leptosphaeria maculans causes blackleg disease on Brassica napus, an economically important oilseed crop. Brassica juncea has high resistance to blackleg and is a source for the development of resistant B.napus varieties. To transfer the Rlm6 resistance gene from B.juncea into B.napus, an interspecific cross between B.napus Topas DH16516 and B.juncea Forge was produced, followed by the development of F-2 and F-3 generations. Sequence characterized amplified region (SCAR) and cleaved amplified polymorphic sequence (CAPS) markers linked to the L.maculans resistance gene Rlm6 were developed. Segregation of SCAR and CAPS markers linked to Rlm6 were confirmed by genotyping of F-2 and F-3 progeny. Segregation of CAPS markers and phenotypes for blackleg disease severity in F-2 plants had a Mendelian ratio of 3:1 in resistant vs. susceptible plants, respectively, supporting the assumption that genetic control of resistance was by a single dominant gene. The molecular markers developed in this study, which show linkage with the L.maculans resistance gene Rlm6, would facilitate marker-assisted backcross breeding in a variety development programme.