The TCP family is a group of phylogenetically related, plant-specific transcription factors (TFs). Many functional studies have been conducted on TCP TFs and progressed over the past years. However, little is known about their possible involvement in flowering time regulation.
In a recent issue of journal Plant Physiology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) provided evidence that class II TCPs function as key components of the regulatory network that modulates the onset and progression of floral initiation via their role in the flowering locus T (FT)-FD-controlled flowering pathway.
The researchers used molecular and genetic approaches to investigate the roles of class II TCP TFs in flowering time regulation.
They first investigated the possible regulatory roles of three TCP TFs in flowering in Arabidopsis and analyzed the expression patterns of both flowering time-related genes and floral meristem identity genes.
They then used the yeast two-hybrid system to identify the potential interaction partners of flowering time-related genes. They also investigated whether all members of the TCP family can interact with FD in flowering time regulation.
The results showed that altered expression levels of the class II CIN TCP TF genes affect floral initiation. The class II Cincinnata (CIN)-like TCP TFs acted as transcriptional activators to control flowering by directly binding the promoter of Apetala1 (AP1).
Moreover, TCPs directly interacted with FD causing additive activation of AP1 expression, and those TCPs function redundantly among themselves or synergistically with FT and FD to positively regulate flowering in an AP1-dependent manner.
“Our results provide compelling evidence that class II CIN TCP TFs act directly at the AP1 promoter to enhance its transcription, thus further elucidating the molecular mechanisms underlying the regulation of photoperiodic flowering in Arabidopsis”, said Dr. Chen Ligang, correspondence author of the study.