Inheritance of cabbage head formation in crosses of cabbage × ornamental cabbage and cabbage × kale

Abstract

We investigated the inheritance of head formation in Brassica oleracea by using two crosses, cabbage × ornamental cabbage and cabbage × kale. The degree of head formation (DHF) was classified into nine grades ranging from non-heading to full heading. DHF in the two F2 populations showed a continuous distribution. The variance of F3 offspring selected for full heading or non-heading was large. The DHF distributions in the F3 offspring selected for moderate heading or randomly selected F3 populations were similar to those of the respective F2 populations, but had smaller average values and variance. However, the realized heritability in F3 offspring was similar in full-heading and non-heading selections. Our findings suggest that head formation is a quantitative trait controlled additively with low dominance effects. In comparisons of leaf developmental patterns among the parents, only cabbage showed a change in leaf shape becoming wider because of the shorter petiole length with increasing leaf position. These findings suggest that cabbage acquired the developmental changes in leaves required to form a head during the process of domestication.