A wide variation of morphological traits exists in Brassica rapa L. and Brassica oleracea L., and cultivated vegetable varieties of these species are consumed worldwide. Flowering time is an important agronomic trait in these species and varies among varieties or cultivars. Especially, leafy vegetable species need a high bolting resistance. Isolation of FLOWERING LOCUS C (FLC), one of the key genes involved in vernalization, has now provided an insight into the molecular mechanism involved in the regulation of flowering time, including the role of histone modification. In the model plant Arabidopsis thaliana, FLC plays an important role in modulating flowering time. The response to vernalization causes an increase in histone H3 lysine 27 tri-methylation (H3K27me3) that leads to reduced expression of the FLC gene. B. rapa and B. oleracea both contain several paralogs of FLC at syntenic regions identified as major flowering time and vernalization response quantitative trait loci (QTL). We introduce the recent research, not only in A. thaliana, but also in the genus Brassica from a genetic and epigenetic view point.
Part of the book: Brassica Germplasm