Figure 10.

pSuT is required for maximal freezing tolerance. A and B, Analysis of cold-associated changes in pSuT transcript levels. The transcript level of plants cultivated at 22°C served as a reference (set to 1). Data were normalized to the expression of the housekeeping genes At5g08290 and At1g13320 and represent means of four biological replicates ± se. Significance differences were calculated using one-factor ANOVA (**, P ≤ 0.01). A, Analysis of pSuT transcript levels of wild-type plants cultivated for 4 weeks at 22°C under short-day conditions, then at 4°C for 24 h under short-day conditions. B, Analysis of pSuT transcript levels of wild-type plants cultivated for 4 weeks at 22°C, then at 4°C for 24 h in the dark. C, Sugar levels in 4-week-old rosette leaves of wild-type (dark gray bars), pSUT-kd (gray bars), and pSuT-ko (light gray bars) plants after exposure to cold (4°C, short-day conditions) for 24 h. Frc, Fru. Data are means from 10 plants per line ± se. Significant differences compared with the wild type were calculated using one-tailed Student’s t test (*, P ≤ 0.05). D, Analysis of the electrolyte leakage from leaves of wild-type (dark gray bars), pSuT-kd (gray bars), and pSuT-ko (light gray bars) plants after 4 d of cold (4°C) acclimation. Electrolyte leakage from mutant plant leaves was normalized to leakage from wild-type leaves (set to 100%). Data represent means of at least 18 biological replicates ± se. Significant differences compared with the wild type were calculated using one-tailed Student’s t test (*, P ≤ 0.05 and **, P ≤ 0.01).