Construction of Near Isogenic Lines in Brassica oleracea

The single species Brassica oleracea encompasses a remarkable diversity of morphotypes, including cauliflower, broccoli, kohlrabi, marrowstem kale, cabbage, and Brussels sprouts as well as rapid-flowering morphologically simple genotypes reminiscent of Arabidopsis. To dissect the molecular basis of phenotypic diversity among morphotypes, a mapping population that offers fine-scale resolution and is sensitive enough to detect both large effect and small effect QTL is of high value. Near isogenic lines (NILs) meet these criteria. Here, two NILs population are being developed. A rapid cycling line, TO1434, with short generation time and self-compatibility, is the recurrent parent. Inbred strains of cauliflower (Orange) and cabbage (Badger Inbred), which represent diverse lineages within B. oleracea, are donor parents. We have reached the BC₄F₁ generation for both populations, in which we expect an average of 2.5 introgressed segments per each family. DNA from each family has been extracted and ready for genotyping to reveal introgressed segments, and target them for identification of NILs in BC₄F₂ progeny. We anticipate that NILs developed in rapid-cycling background will reveal the genetics of complex morphological variations in this fascinating species, and provide valuable material for rapid genetic analysis of many other traits in B. oleracea.