Isolation Of B-function Mads-box Genes In Camellia Japonica And Its Potential Role In Double Flower Formation

Camellia is one of the top ten traditional flowers in China, and also is one of the precious flowers in the world. In the natural states the camellia flowers is signal form and how to changes into double flowers in biology evolution is our research purpose. From"ABC model"theory of floral development we knew that B-function was key role in the second and third whorl in eukaryote plants, so, this phenomenon was implied that B-function may be play key factor for double flowers formation in camellia. Although the function of B-function gene was clearly in model plant, but it's role in double flowers formation were unknown in camellia.To investigate the mechanism of B-function gene for double flower development in Camellia, B-function gene cDNA was cloned by RT-PCR and RACE methods and named CjHGLO1, CjHGLO2, CjHDEF and CjHTM6 respective, and its function and expression pattern were analyzed. The results showed that the coding protein of B-function gene was completely expressed in Escherichia coli BL21 by IPTG induced, this phenomenon indicated that the isolated genes had completed structure. The sense gene of B-function was transforred into Arabidopsis and the results showed that the sepals and petals were fused by CjHGLO1 gene, and the fused tendency started from based part. The phenotype was not changed by sense CjHGLO2 gene. The first-whorl sepals were completely transforrmed into petals by sense CjHDEF gene, so that all of pepals was eight. The stigma was extended when the flower buds was not opening in Arabidopsis by sense CjHTM6 gene, and the petals growth was not cohered with stigma, meanwhile, the stamens has disappeared.The expression pattern of B-function gene among signal,semi-double,anemone form,peony form and formal double was studied by Real-time PCR method. The results showed that B-function gene GLOBOSA1 (GLO1) and GLOBOSA2 (GLO2) had high expression at the part with petal identity, and had low or no expression at or near the part with sepal identity, and these kinds of expression showed that gene played an important role in determining petal identity. B-function gene DEFICIENS (DEF) and TOMATO MADS BOX GENE6 (TM6) had high expression at the fused part of stamens, and this implied the importance of gene when stamen transforrmed into petal. The petals were increased and the flower whorls were decrease when the signal transformed into double flowers in camellia, and expression domain of B-function was also toward to the central petals, the simplest explanation for this was that the B-function was removal toward the flower center, this phenomenon explained that the B-function gene was high conservative.Our analyses of the paper, the phenomenon of the sepals petaloid in camellia is extented of expression domain by B-function gene, and it is key factor in double flower formation. It has multiple origins including accumulation origin,sepal origin and stamens-carpels origin in double flowers formation in camellia. Thus, B-function gene is very important when signal evolved into double flowers in camellia.