Figure 9.
Freezing tolerance is reduced by a mutation of MYB15 that prevents phosphorylation. (A) Ion-leakage test without cold acclimation. Empty vector (EV), MYB15 OX and MYB15S168A OX transgenic plants were used. The ion leakage experiment was repeated twice with three replicates per experiment. Shown are results from one representative experiment. Data are presented as the mean ± SD of three independent experiments. P < 0.05 (*), P < 0.01 (**) and P < 0.001 (***) indicate statistically significant changes. (B and C) Freezing survival assay without acclimation. Three-week-old plants grown in soil at 22°C were incubated at 4°C for 1 h, followed by freezing treatment for 2 h at −8°C. After the freezing treatment, plants were incubated at 4°C for 1 day and returned to normal growing conditions for 5 days before photography (B) and survival rate measurements (C). Data are presented as the mean ± SD of three independent experiments. P < 0.01 (**) and P < 0.001 (***) indicate statistically significant changes.