Figure 6. COP1 acts downstream of EIN3 to modulate ethylene-promoted hypocotyl growth.

(A) Morphological observations and (B) statistical analyses of hypocotyl length after 5 days of incubation in MS medium supplemented with or without 10 µM ACC. The data indicate the mean values plus the SD from three independent experiments with approximately 30 seedlings. P-values (ACC treatment vs. non-treatment) were determined with a two-tailed Student's t-test assuming equal variances (*P<0.05). (C) HY5 accumulation with or without ACC treatment. Protein extracts were prepared from 5-day-old seedlings after treatment with or without 25 µM ACC for 15 h. Immunoblotting was performed with anti-HY5 and -TUB4 antibodies. The TUB4 signals indicate equal protein loading. Because the ein3-1 and GUS-COP1 were produced in different backgrounds, an F1 hybrid of No-0×Col-0 was used as the control. The numbers below the gel indicate the protein levels of HY5.