Abstract: AGL24（AGAMOUS-LIKE 24）was a key regulator to activate flowering in Brassica juncea. In order to clarify the expression characteristics of AGL24 gene and its protein interaction mechanism with another three regulators（SOC1，SVP and FLC）in flowering pathways，we cloned AGL24 gene of 680 bp in‘Qingyejie’mustard germplasm of Brassica juncea，which encoded 221 amino acids. Sequence analysisshowed that AGL24 protein in Brassica juncea has four domains，M，I，K and C，respectively containing 59，11，102 and 47 amino acids. And it has the closest relationship with AGL24 in Brassica napus. Expression analysis of qRT-PCR revealed that AGL24 gene can express in leaf as well as shoot apex during the flowering pathways of vernalization and long-day photoperiod. AGL24 has the low level expression at the vegetative phase but rapidly rising expression at reproductive phase. The peak of AGL24 gene expression in long-day photoperiod pathway is more sooner than that of vernalization pathway. Moreover，yeast two-hybrid assays showed that AGL24 can interact with the flowering signal integrator SOC1. And the fused strains were incubated on QDO/X-α-Gal/AbA plate and blue colonies were found，suggesting that the yeast fusion reporter genes AUR1-C，HIS3，ADE2，and MEL1 were activated. We also subcloned two truncated forms AGL24★ and SOC1★ after respectively removing MADS domain of AGL24 and SOC1，and found that AGL24★ also can interact with SOC1★ in yeast. β-galactosidase activity assays indicated that the interaction strength of AGL24★ and SOC1★ was much stronger than that of AGL24 and SOC1. However，neither AGL24 nor AGL24★ can interact with the core repressor SVP in the photoperiod pathway，and it was the same with the core repressor FLC in the vernalization pathway. The results suggested that AGL24 was not the direct protein target of SVP or FLC.

Key words: Brassica juncea, flowering regulation, AGL24, yeast two-hybrid system