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. 2022 Feb 28;34(6):2286–2308. doi: 10.1093/plcell/koac073

Figure 2.

Figure 2

COP1 positively regulates ABA signaling during seedling growth in darkness through ABI5. A, Immunoblots showing the abundance of PYR1, OST1, ABI1, ABI2, and ABI5 in Col-0 and cop1 mutant seedlings before and after ABA treatment. Four-day-old Col-0, cop1-4, and cop1-6 mutant seedlings grown in darkness were first treated with 50-μM ABA for the indicated times, and then harvested and subjected to immunoblotting using antibodies against PYR1, OST1, ABI1, ABI2, and ABI5 proteins. Anti-RPN6 or anti-HSP was used as sample loading control. Numbers below the immunoblots indicate the relative band intensities of the respective proteins normalized to those of loading control for each panel. The ratio of the first band was set to 100 for each blot. The asterisks indicate nonspecific bands. B, Germination rate measurements. Hydrated seeds for Col-0, cop1-4, cop1-4 ABI5-GFP, and cop1-4 ABI5-MYC were sown on MS medium or MS medium containing 0.5-µM ABA. Error bars represent sd of three independent sets of seeds, each set containing 50 seeds. *P < 0.05, **P < 0.01, and ***P < 0.001 (Student’s t test; Supplemental Data Set S1) for the indicated pairs of seeds. C, Phenotypic analyses of 5-day-old dark-grown Col-0, cop1-4, ABI5-GFP, cop1-4 ABI5-GFP, ABI5-MYC, and cop1-4 ABI5-MYC seedlings. The seedlings were grown vertically on MS medium or MS medium with various ABA concentrations for 5 days in darkness. Bar = 1 cm. D, Seedling establishment rate measurements. Col-0, cop1-4, cop1-4 ABI5-GFP, and cop1-4 ABI5-MYC seedlings were grown horizontally on MS medium or MS medium containing 0.5-µM ABA in darkness. Error bars represent sd of three independent pools of seedlings, each pool containing 50 seedlings. *P < 0.05, **P < 0.01, and ***P < 0.001 (Student’s t test; Supplemental Data Set S1) for the indicated pairs of seedlings.