Figure 4.
Effect of Growth Temperature on FT/TFT Function.
(A) and (B) Plants of different genotypes were grown at 23°C (A) or at 12°C (B) under otherwise similar short-day growth conditions (Table 1, B treatments). While low temperatures slightly increased leaf size of wild-type (Ler) plants, it severely increased leaf size and eliminated leaf curling of Pro35S:FT, Pro35S:TFT#3, and Pro35S:TFT#7. Note that cold temperatures had no noticeable effect on Pro35S:TFT#3 in fd-1 plants, besides a reduction in petiole length. Plants in (A) are 21 d old, and in (B), they are 26 d old. Dashed lines within panels border between different genotypes, grown together under identical conditions, and photographed separately at the same age. Bar = 1 cm.
(C) Flowering time of Pro35S:FT and Pro35S:TFT#3 plants at different temperatures. Flowering time is measured by counting rosette (gray) and cauline (black) leaves. Both genotypes responded to lower temperatures by an increase in rosette leaf number. Since no corresponding reduction in cauline leaf number occurred in Pro35S:FT plants, flowering was significantly delayed. #, repeat number of experiment. Mean leaf number is shown ± se (n = 5 to 22).