Key message We identified the loss of BoFLC gene as the cause of non-vernalization requirement in B. oleracea . Our developed codominant marker of BoFLC gene can be used for breeding program of B. oleracea crops . Abstract Many species of the Brassicaceae family, including some Brassica crops, require vernalization to avoid pre-winter flowering. Vernalization is an unfavorable trait for Chinese kale ( Brassica oleracea var. ch...