Comparative mapping of loci controlling winter survival and related traits in oilseed Brassica rapa and B. napus

Kole, C.; Thormann, C. E.; Karlsson, B. H.; Palta, J. P.; Gaffney, P.; Yandell, B.; Osborn, T. C.

doi:10.1023/a:1019759512347

Winter survival is an important characteristic of oilseed Brassica that is seeded in the fall in northern climates, and it may be affected by genetic variation for other cold-regulated traits, such as freezing tolerance and vernalization responsive flowering time. We analyzed immortalized populations of oilseed Brassica rapa (recombinant inbred lines) and B. napus (double haploid lines) derived from crosses of annual and biennial types in order to compare the map positions and effects of quantitative trait loci controlling winter survival, nonacclimated and acclimated freezing tolerances, and flowering time. The B. napus population was evaluated in multiple winters, and six of the 16 total significant QTL for winter survival were detected in more than one winter. Correspondence in the map positions of QTL controlling different traits within species provided evidence that some alleles causing greater acclimated freezing tolerance and later flowering time also contributed to increased winter survival. Correspondence in the map positions of QTL between species provided evidence for allelic variation at homologous loci in B. rapa and B. napus. The potential role of some candidate genes in regulating these traits is discussed.