Comparative mapping of quantitative trait loci sculpting the curd of Brassica oleracea

The enlarged inflorescence (curd) of cauliflower and broccoli provide not o nly a popular vegetable for human consumption, but also a unique opportunit y fur scientists who seek to understand the genetic basis of plant growth a nd development. By the comparison of quantitative trait loci (QTL) maps con structed from three different F-2 populations, we identified a total of 86 QTL that control eight curd-related traits in Braasica oleracea. The 86 QTL ma) reflect allelic variation in as few as 67 different genetic loci and 5 4 ancestral genes. Although the locations of QTL affecting a trait occasion ally corresponded between different populations or between different homeol ogous Brassica chromosomes, our data supported other molecular and morpholo gical data in suggesting that the Brassica genus is rapidly evolving. Compa rative data enabled us to identify a number of candidate genes from Arabido psis that warrant further investigation to determine if some of them might account fur Brassica QTL. The Arabidopsis/Brassica system is an important e xample of both the challenges and opportunities associated with extrapolati on of genomic information from facile models to large-genome taxa including major crops.