Protein network of FT1 and FT2 in poplar reproduction
Understanding the signaling mechanisms that determine juvenile-to-mature transition and bud fate is vital for controlling tree reproduction. FD-like proteins also appear to be important for initiating reproductive development. In this study, phylogenetic analysis showed that three FD-like genes (FDL1, FDL2, and FDL3) are present in the poplar genome. FDL1 and FDL2 are products of a recent whole genome duplication event while FDL3 escaped such duplication. Yeast two-hybrid assays demonstrated that FT1 and FT2 proteins interact with FDL3 protein, but not with FDL1 or FDL2 protein. Analysis of the expression levels of FD-like transcripts in Populus deltoides via quantitative real-time PCR showed that FDL3 abundantly expresses in the shoot apex where it probably interacts with FT1 in late winter and early spring. Following the duplication event, FDL1 and FDL2 appear to have diverged in function as they express in a number of tissues in the fall, winter, and spring.