Abstract: SVP and FLC were the key regulators in plant flowering pathways. For further study on the molecular mechanism of flowering control in Brassica juncea Coss.（mustard），the protein interaction domains between SVP and FLC were screened via yeast two-hybrid system. The truncated genes of SVP1- 5and FLC1- 5were respectively subcloned from yeast recombination plasmids pGADT7SVP and pGBKT7FLC. The proteins encoded by SVP1- 5 or FLC1- 5 had MI-domain，MIK-domain，K-domain， IKC-domain and KC-domain，respectively. SVP1- 5 truncated forms were fused into bait plasmid pGADT7，which were designated as pGADT7SVP1- 5 and then transformed into Y187 yeast stains. FLC1–5 truncated forms were fused into prey plasmid pGBKT7，which were designated as pGBKT7FLC1- 5 and then transformed into Y2HGold stains. All the transformed yeast stains were not autoactivation and toxicity. The yeast stains of pGADT7SVP2- 5 and pGBKT7FLC could mate into zygotes and grew on selective agar plates QDO/X/A with blue stains. The results showed that SVP2- 5 truncated forms and FLC protein could act with each other to form heterodimers. K domain of SVP（SVP3）was the key amino acid region to independently mediate the interactions between SVP and FLC.

Key words: Brassica juncea Coss, truncated form, SVP, FLC, yeast two-hybrid system