1993 Volume 39 Pages 22-27
Suspension-cultured cells of wheat (Triticum monococcum L.) were cultured in media containing abscisic acid (ABA) and high concentrations (0.44 or 0.88M) of mannitol or sucrose and changes in their freezing tolerance were investigated. In a medium with ABA, freezing tolerance of the cells increased rapidly and achieved a maximal level after 7-10 days of culture. Optimal concentration of ABA for increasing the freezing tolerance was 10 to 20 mg/l. Survival rate of the cells which were cultured in a medium containing 10mg/l ABA for 7 days was very high even at the freezing temperature of -50℃, whereas that of control cells was very low (<10%) at -15℃. Increase in the freezing tolerance was also observed in a mannitol or sucrose medium but the effect of these substances was less than that of ABA. The osmolarity of cell extracts from the cells increased with these treatments. However, there was no correlation between the degree of freezing tolerance and the osmolarity of cell extract. Protein analysis using SDS-PAGE showed that distinct changes in protein profile were induced by ABA in the medium but not induced by high concentrations of sucose or mannitol. These results suggest that different mechanisms are involved in the development of freezing tolerance of these cells for the two treatments.
