Analysis of linkage disequilibrium in canola-quality winter rapeseed (Brassica napus L.)

摘要

The extend and structure of linkage disequilibrium (LD) was analysed in a set of 90 canola quality winter rapeseed lines derived from six breeding companies using 471 AFLP markers. To determine recombination frequencies the AFLP markers were also scored in 94 lines of a segregating doubled haploid population from a cross between the winter rapeseed variety 'Express' and a resynthesized rapeseed line, 'R53'. Only 11.36% of the 110,685 pair wise combinations of the 471 AFLP markers were in significant LD with a mean r2 of 0.13, showing a low overall level of linkage disequilibrium in canola quality winter rapeseed.Mean r2 values of linked and unlinked marker pairs in significant LD of 0.32 and 0.08, respectively, indicated that the major cause for linkage disequilibrium was linkage while linkage disequilibrium due to population structure, genetic drift or selection was negligible. Among linked markers linkage disequilibrium was high for closely linked markers but decayed rapidly within a few cM. The results are discussed with respect to the breeding history of rapeseed and the feasibility of a global approach to association analysis.