Abstract: MADS-box gene family has played important roles in the floral organs development. In order to investigate the function of A-class genes for double flower development in Camellia japonica, a 888 bp full-length cDNA sequence of AG homologous gene was cloned from early flower bud of C.japonica ‘Jinpanlizhi’, named CjAGL6(GenBank accession JX657333). It contains an opening reading frame of 747 bp, a 5′-untranslated region (UTR) of 37 bp, a 3′-UTR of 141 bp. Amino acids sequence alignment showed that CjAGL6 gene encodes the protein with 248 amino acids, and the homology is more than 76% with Actinidia chinensis and Diospyros digyna. Real-time PCR analysis showed that the relative expression level of this gene was as follows: later flower bud>medium flower bud>early flower bud>squaring stage, it increased slowly at the initial stage and then sharply decreased to the lowest. In different floral organs of ‘Jinpanlizhi’, the highest expression was in style, next in petalody stamens, upper stamens and ovary, the lowest in sepals and petalody sepals. The tendency was the high expression in inter floral organs and the low in outer floral organs. The forming of double flower is the synergistic result of multiple genes. CjAGL6 gene may have some functions in this process.

Key words: Camellia japonica, CjAGL6 gene, sequence analysis, real-time PCR, expression