The potential role of B-function gene involved in floral development for double flowers formation in Camellia changii Ye

Abstract

Camellia changii Ye, a rare and endangered species, has a phenotype that sepals frequently transform into petals. We assumed that this change would cause single C. changii Ye turned double flowers and this was confirmed by the double flowers we found in grafted C. changii Ye. The microstructure of floral organs showed that: in perfect petals, the anthocyanin is distributed in the upper and lower epidermis; in petaloid sepals, anthocyaninin had both sepal and petal identities and sepals gradually transformed into petals; in spot-petaloid sepals, anthocyaninin is only distributed in upper epidermis. 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 the stamens and this implied the importance of gene when stamen is transformed into petal. Thus, B-function gene is very important when C. changii Ye evolved into double flowers.

Key words: Petaloid phenotype, double flowers, B-function gene, Camellia changii Ye, real-time polymerase chain reaction (PCR).