Abstract: BoFLC3 gene from Brassica oleracea and AtFT gene from Arabidopsis were overexpressed alone or together in Brassica juncea. The results showed constitutive expression of the BoFLC3 gene in Brassica juncea significantly delayed flowering under long-day photoperiods as well as short-day photoperiods. Vernalization treatment induced earlier flowering of BoFLC3 overexpression plants than unvernalized transgenic control but still were flowering later than the wild type plants; the overexpression of the AtFT gene could induce early flowering in Brassica juncea. The flowering time of BoFLC3 and AtFT genes co-expression plants after cross were almost at the same time compared with the wild type plants，indicated the effects of the over-expression of the BoFLC3 and AtFT genes on flowering time could cancel each other out. Moreover，the cold-tolerance was enhanced by constitutive expression of the BoFLC3 gene in Brassica juncea，but no cold-tolerance changes were observed in AtFT overexpression plants. The results indicated the BoFLC3 should involve in plant cold-tolerance regulation.

Key words: Brassica juncea, BoFLC3 gene, AtFT gene, flowering time, cold-tolerance