Figure 3.

ABA regulates ABI5 accumulation within a narrow developmental window. (A) WT Ws seeds were kept in darkness at 4°C for 3 days without ABA and then transferred to 5 μM ABA plates at the indicated times poststratification. ABI5 levels were monitored by Western blot analysis. Photographs depict representative seedlings 5 days after the different treatments. (Scale bar, 0.5 mm.) (B) ABI5 protein level rapidly decreased on ABA removal. WT Ws seeds treated with ABA (5 μM) as described in Fig. 1B were transferred to plates without ABA, 2 days poststratification. ABI5 levels were monitored by Western blot analyses as described in Fig. 1. (C) WT Ws seeds eventually germinated in the presence of ABA (5 and 10 μM). (Scale bar, 0.5 mm.) (D) WT Ws seedlings 4 and 30 days poststratification in the presence or absence of ABA (5 μM). (Scale bar, 0.5 mm.)