Figure 1.

Antagonistic effects of GA and ABA on growth of petals in G. hybrida. G. hybrida was grown in a greenhouse under the conditions described in Materials and Methods. Plants with inflorescences at stage 1.5 were sprayed with deionized water (with 0.1% ethanol) (Control), 10 μM GA₃ or 50 μM ABA and were subjected to morphological characterization (A) and petal length measurement (B) after 9 days of treatment. Sixty or more ray petals were measured for each treatment and the value are given as average lengths ± SE. Representative examples of inhibition of GA- or ABA-derived effects on petal growth by PAC (10 μM) or FLU (0.1 μM) are shown in (C,D), for which the control petal length was set as 1. One mm² blocks at the center of the top, middle or basal regions of the petal are indicated in (E). Detached petals treated with Control, 10 μM GA₃ or 50 μM ABA for 9 days were used for morphological characterization of adaxial epidermal cell using a confocal microscope (G) and measurement of elongation rate of each petal region (F, n = 10) or cell (H, n > 100). Three biological replicates were performed for each measurement. Values are given as mean ± SE. Letters above the bars indicate significant differences between the respective values (p < 0.05). Scale bar represents 1 cm (A) or 50 μm (G).