Figure 1.

Freezing tolerance of protoplasts isolated from leaves of nonacclimated plants of A. thaliana: RLD (○), the wild type, and T8 (•), which constitutively expresses the COR15a gene. Protoplasts were suspended in either a 0.400 (A and B) or 0.413 (C and D) osmol sorbitol solution before freezing. (A and C) Survival after a conventional freeze/thaw treatment. (B and D) Survival after a freeze/hypertonic-thaw treatment. Survival (percentage of the unfrozen control) was determined by staining with fluorescein diacetate (17). Results shown are the mean and SD of three experiments.