ABA2 promoter activity in response to diverse stress. A, Determination of GUS activity under drought condition. Aerial parts of tissues were removed from 21-d-old plants grown in soil and immediately placed on an electronic dry box with 40% relative humidity for 1.5 and 3 h. B, Determination of GUS activity under diverse stress. Plants were grown in soil for 21 d and subsequently treated with cold (4°C; 3 d), drought (4 d), flooding (1 d), and salt stresses (125 and 250 mm NaCl, each for 1 d), respectively. Control samples were harvested at 21 dap, at the beginning of stress treatments. C, Determination of GUS activity under Suc and NaCl treatments. Seedlings were grown on 1% Suc agar plates with or without 125 or 250 mm NaCl for 14 d. Results in A, B, and C are the means ± sd of three independent experiments, each experiment with a duplicate. Transgenic plants harboring the ABA2GUS transgene were under wild-type (lines 1-11 and 4-12) and aba2 mutant (lines 3-6 and 3-12) backgrounds.