Abstract:

AGAMOUS-LIKE 18（AGL18）is a key regulatory factor in flowering time control of Brassica juncea. In order to clarify the regulatory mechanism of AGL18 protein interact with SOC1 in flowering pathways，AGL18-1 gene from reproductive shoots as well as AGL18-2 and AGL18-3 from vegetative shoots in‘QJ’germplasm of Brassica juncea，were cloned respcetively. AGL18-1，AGL18-2 and AGL18-3were members of AGL18 family and respectively encoded 257，257 and 258 amino acids. Sequences analysis showed that they were more than 90% similar to Brassica rapa and Brassica napus. Both Yeast two hybrid and BiFC showed that SOC1 protein could not interact with AGL18-1，AGL18-2 or AGL18-3. Yeast one hybrid and Dual-Glo^® Luciferase assays indicated that SOC1 promoter could interact with AGL18-1 but not AGL18-2 and AGL18-3. To screen the interaction regions of AGL18-1/SOC1，the M-domain and IKC-domain truncations of AGL18-1 protein were separated and found that only the M-domain truncation could interact with SOC1 promoter. It suggested that M-domain was the key region that mediated the interaction between AGL18-1 and SOC1 promoter. The work provided valuable information for in-depth studies on the molecular mechanisms of AGL18 protein with SOC1 and the flowering time in Brassica juncea.

Key words: Brassica juncea, AGL18, SOC1, flowering regulation, interaction