Figure 7.

The cuticle of seed coat and the sensitivity of perforated seeds to ABA during germination. A, Transmission electron micrographs of the cuticle layer of Col-0 (top) and cer9-2 (bottom) seed coats. The cuticular layer is indicated by the arrows. Bars = 0.2 μm. B, Germination rates of perforated seeds under ABA treatment. Seeds of Col-0 and cer9-2 were perforated with a surgery stab knife, sown on 1/2 MS medium supplemented with 0 or 1 μm ABA, and incubated at 4°C for 3 d before being moved to 22°C. Seed germination was scored 2 d later. Seeds were considered germinated when the radicles emerged. Col-0 P and cer9-2 P represent perforated Col-0 and cer9-2 seeds, respectively. Data are means ± se of three replicates each with at least 30 seeds.