Asteraceae comprises of approximately 10% of all angiosperm plant species. These species are well known
for their highly compressed inflorescences known as capitula which consists of morphologically different
types of flowers: ray, trans and disc flowers. This immense morphological difference excels Gerbera as an
ideal plant to study flower type differentiations. Even though this complex process is governed by several
genes, the ray flower identity is believed to be greatly influenced by GhCYC3 promoter mediated gene
regulations. In previous studies two TCP transcription factors (TF): GhCIN1and GhCIN2, and two MADS
TFs: GAGA1 and RCD5 were identified as the potential upstream regulators of GhCYC3. So, the aim of this
study is to test whether these potential upstream regulators physically bind to GhCYC3 promoter in in vitro
conditions. In order to achieve the goal, these transcription factor proteins from Gerbera hybrida were
successfully expressed in E. coli and purified as fusion proteins to maltose-binding protein (MBP). Physical
binding of the purified fusion proteins to the putative target DNA sites in the promoter region of GhCYC3
gene was tested by electrophoretic mobility shift assay (EMSA). The results showed that none of the gerbera
transcription factors (GhCIN1, GhCIN2, GAGA1 and RCD5) bind to their putative target sites under the
condition tested in this study. However, it might not be justifiable to deduce that these TFs do not interact
with GhCYC3 promoter. The absence of in vitro interaction between the tested TFs and GhCYC3 promoter
might be caused by either lack of proper folding and activity of the TFs or absence of co-factors which are
available in vivo.
