MAPPING OF RFLP AND QUALITATIVE TRAIT LOCI IN BRASSICA-RAPA AND COMPARISON TO THE LINKAGE MAPS OF BRASSICA-NAPUS, BRASSICA-OLERACEA, AND ARABIDOPSIS-THALIANA

A linkage map of restriction fragment length polymorphisms (RFLPs) was constructed for oilseed, Brassica rapa, using anonymous genomic DNA a nd cDNA clones from Brassica and cloned genes from the crucifer Arabid opsis thaliana. We also mapped genes controlling the simply inherited traits, yellow seeds, low seed erucic acid, and pubescence. The map in cluded 139 RFLP loci organized into ten linkage groups (LGs) and one s mall group covering 1785 cM. Each of the three traits mapped to a sing le locus on three different LGs. Many of the RFLP loci were detected w ith the same set of probes used to construct maps in the diploid B. ol eracea and the amphidiploid B. napus. Comparisons of the linkage arran gements between the diploid species B. rapa and B. oleracea revealed s ix LGs with at least two loci in common. Nine of the B. rapa LGs had c onserved linkage arrangements with B. napus LGs. The majority of loci in common were in the same order among the three species, although the distances between loci were largest on the B. rapa map. We also compa red the genome organization between B. rapa and A. thaliana using RFLP loci detected with 12 cloned genes in the two species and found some evidence for a conservation of the linkage arrangements. This B. rapa map will be used to test for associations between segregation of RFLPs , detected by cloned genes of known function, and traits of interest.