Figure 6.

CBF2 is more important than CBF1 or CBF3 in cold acclimation. A, Electrolyte leakage assay conducted on nonacclimated plants grown at 23°C. B, Electrolyte leakage assay conducted on cold-acclimated (4°C for 7 d) plants. C and D, Sensitivity of cold-acclimated plants to freezing. Plants were grown on MS medium for 12 d and were then transferred to 4°C for cold acclimation. The acclimated plants were subjected to freezing at −7°C for 1 h. The percentage of plants that survived was determined after 5 d of recovery at 23°C. C shows the phenotype of seedlings before (upper) and after (bottom) freezing treatment. D shows the survival rates of freezing-treated seedlings after 5 d of recovery at 23°C. All experiments were performed more than three times with similar results, and results from one representative experiment are shown. Error bars in A, B, and D indicate the sd (A and B, n = 3; D, n = 4). Different letters represent statistically significant differences (P < 0.05, one-way ANOVA).