Figure 2.

Low GA Levels Stimulate ABI5 Activity to Repress Seed Germination and Are Associated with ABI5 Protein Phosphorylation.

(A) Images show wild-type (Ler) transformed plants constitutively expressing HA-ABI5 protein (WT/35S:HA-ABI5 plants) under normal conditions or treated with low PAC concentrations (0.125 μM) that do not prevent wild-type seed germination. Photographs were taken after seed imbibition at the indicated times. Percentage of germination on PAC at 96 h is indicated.

(B) Protein gel blot analysis showing differences in HA-ABI5 protein mobility from protein extracts isolated from WT/35S:HA-ABI5 seeds. Plant material was harvested at 48 h after seed imbibition under the indicated conditions (PAC, 0.125 μM; GA, 50 μM; ABA, 0.5 μM). An antibody to HA was used to reveal HA-ABI5 protein. The gel image is duplicated at bottom with a dashed line to facilitate the comparison of protein mobility in each lane.