Genetic Transformation and Analysis of Protein- Protein Interaction of Class B MADS-Box Genes from Dendrobium moniliforme

In angiosperm, flower formation has been initiated by transition of adult vegetative phase to reproductive phase under controlling of plant endogenous signals like hormone and circadian rhythm, and external factors such as photoperiod and temperature (Taiz and Zeiger, 2010). Floral organs of angiosperm are generally arranged in four whorls from outer part into inner part of a flower comprise; sepal-petal-stamen-carpel respectively. Analysis of molecular mechanism controlling flower development reveals that the formation of floral organs concerns functions of a group of transcription factors namely the ABC genes family. Coen and Meyerowitz (1991) have formulated the classical ABC model to explain function of these floral organ identity genes. Based on the classical ABC model, class A gene consists of APETALA1 (AP1) and APETALA2 (AP2) from Arabidopsis, act to specify sepal in whorl1. Combination of class A and class B genes, such as APETALA3 (AP3) and PISTILLATA (PI) in Arabidopsis and DEFICIENS (DEF) and GLOBOSA (GLO) in Antirrhinum, is necessary for petal and stamen development in whorls 2 and 3, respectively. A combination of class B and class C genes including AGAMOUS (AG) in Arabidopsis controls stamen development in whorl 3. The class C gene alone specifies carpel development in the forth floral whorl.