Functional analyses of cultivated strawberry FT and TFL1 homologs

Previously, we cloned the cDNAs of FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1) homologs FaFT1 and FaTFL1-1, respectively, from domesticated octoploid strawberries (Fragaria × ananassa Duch.). We produced Arabidopsis transgenic lines containing FaFT1 or FaTFL1-1 to understand their function. We placed the introduced genes under the control of the Cauliflower mosaic virus (CaMV) 35S promoter, and found that FaFT1 over-expression caused no early flowering except for one line at short day conditions, but aerial rosette phenotype instead. From the results and its expression pattern previously investigated, it was speculated that the FaFT1 acts at the vegetative propagation stage including runner formation, but not at the flower inductive stage. In contrast, the over-expression of FaTFL1-1 rescued the tfl1-2 mutant, suggesting that it possesses flower-suppressing ability. From its spatial expression pattern in crowns (stem tissue including meristem), FaTFL1-1 seemed to be related to flower inducing at apical portion of crowns by its down regulation, and to flower suppressing at the basal portion of crowns by its up regulation.