Figure 7.

Effect of ABA treatment on osmotic and freezing stress-induced damage of control and transgenic P. patens plants. Protonema cells of nontransgenic control (NT) and independent transgenic lines expressing wild-type MpABI1 (W-1 to W-6) and MpABI1-d2 (D2-1 to D2-4) were incubated for 1 d with or without 10 μm ABA and used for osmotic stress and freezing treatments. A, Representative results of growth of cells that had been either pretreated with 10 μm ABA (+) or nontreated (−) prior to the osmotic stress treatment by the indicated concentrations of mannitol or NaCl. After 15 min of osmotic stress treatment at room temperature, a piece of protonemata was planted on fresh BCD agar medium and grown at 25°C for 1 week. B, Representative results of growth after freezing of nontransgenic and transgenic plants that had been pretreated with 10 μm ABA for 1 d. All samples were ice inoculated at −1°C and subjected to equilibrium freezing to −5°C. After thawing, a piece of protonemata was planted on fresh BCD agar medium and grown at 25°C for 1 week.