Abstract：Abstract CUP-SHAPED COTYLEDON1 to 3 genes (CUC1-CUC3) play an important role in shoot apical meristem (SAM) function, organ separation and leaf development. BrcCUC3 was cloned from the non-heading Chinese cabbage by the method of homologous sequence amplification and transformed into Arabidopsis thaliana for functional identification. The coding sequence of BrcCUC3 is 1008 bp in length and predicted to encode a typical NAC-domain transcription factor with the protein of 335 amino acids. The corresponding genomic DNA contained three exons and two introns. It was in conformity with the principles of GT-AG. The amino acid sequence analysis showed that it contained a conserved NAC-domain. Phylogenetic analysis revealed that amino acid sequence of BrcCUC3 were high similar to previously described CUC3 proteins from other plant species, especially shares 98%, 97%, and 83% identity with Cabbage, Radish, and Arabidopsis proteins, respectively. In the CUC3 phylogenetic tree of multiple species, BrcCUC3 protein belongs to the Brassicaceae sub-branche of dicot branche. According to the 20 CUC3 amino acid sequences of plants, the phylogenetic tree showed that it indeed reflected the evolution of plants. A real-time PCR was performed to observe the expression profiling of BrcCUC3, the results showed that BrcCUC3 was higher expressed in the different stage leaves of lines with lobed leaf than that in lines with entire leaf. The transformation of BrcCUC3 gene into Arabidopsis thaliana was carried out by floral dipping with the agrobacteria. Comparing with wild-type plants, overexpression of BrcCUC3 cDNA under the control of a CaMV 35S promoter in Arabidopsis caused serrated leaves, modified inflorescence structure with increased apical inflorescence. All the results suggested that BrcCUC3 involved in the regulation of leaf margin and braches development.
