Plant Genome III Conference Plant Genome III Conference
Three agronomic traits, namely self-incompatibility, tolerance to Blackleg disease (Loptosphaeria musculans), and the spring/winter growth habit were analysed using two microspore derived dihaploid (DH) populations of B. napus. These two DH populations have the same male parent, which is a self-compatible spring breeding line with susceptibility to Blackleg disease. The female parents of the two crosses were different, one being a spring line tolerant to Blackleg disease, and another being a winter line susceptible to Blackleg disease, but both were self- incompatible. Data from segregation analyses of over 300 RFLP and RAPD marker loci were obtained for each of the two DH populations. Segregation bias (45%) was observed in some areas of the genome with the cross between the spring lines, but not with the cross between the spring and winter lines. Alleles from both parents however, were equally represented in this spring x spring cross when all loci were considered. Self-incompatibility was mapped as a single Mendelian trait in both populations and tolerance to Blackleg disease was mapped as a quantitative trait only with the spring x spring population. Spring/winter growth hapbit could only be mapped in the cross between the spring and winter lines. The genetic maps derived from both populations will be compared and the effects of localized biased segregation on genetic mapping will be discussed.