Sequence variation and functional analysis of a FRIGIDA orthologue (BnaA3.FRI) in Brassica napus

Background Allelic variation at the FRIGIDA (FRI) locus is a major contributor to natural variation of flowering time and vernalization requirement in Arabidopsis thaliana. Dominant FRI inhibits flowering by activating the expression of the MADS box transcriptional repressor FLOWERING LOCUS C (FLC), which represses flowering prior to vernalization. Four FRI orthologues had been identified in the domesticated amphidiploid Brassica napus. Linkage and association studies had revealed that one of the FRI orthologues, BnaA3.FRI, contributes to flowering time variation and crop type differentiation.