Binding of Arabidopsis FD to an Unusual cis-Regulatory Element – A new Role for the Master Floral Regulator LEAFY?
Flowers are of high economic importance as they produce most of our food and animal feed. The plant-specific transcription factor LEAFY (LFY) has been shown to play important roles in the control of flowering time and floral meristem identity. In this research project we will study how the DNA binding specificity of the LFY protein changed throughout the course of evolution.
Most living plants species are angiosperms, or flower-bearing plants. The processes that control flower development are only partially understood. However, the plant-specific transcription factor LEAFY (LFY), which in most species is encoded by a single gene, has been identified as an evolutionary conserved key regulator of floral meristem identity. Throughout its evolution, the DNA- binding motif recognized by LFY underwent massive changes, raising the question, how expression of genes with “ancient” LFY cis-regulatory elements in their promoter is regulated in modern plants? We have recently identified targets of the Arabidopsis thaliana bZIP transcription factor FD at the genome-wide scale. Interestingly, de novo motif prediction showed that FD can bind to a cis- regulatory element that in many aspects resembles the ancient LFY binding motif, to which we refer to as “new box”.
In this research project we will identify cofactors that target FD to the “new box” in an unbiased approach. In addition, we will test the hypothesis that FD might act as a cofactor that allows LFY in extant angiosperms to bind to ancient cis-regulatory binding sites. If confirmed, this would constitute a novel mode of transcription factor – binding site coevolution. Eventually, the results from the project will help us to better understand the evolution and development of flowers, which are of high economic importance as they – directly or indirectly – produce most of our food and animal feed.