FIGURE 7.

Restored sensitivity of CaAIMK1^K32N-OX plants to abscisic acid (ABA) and drought stress. (A) Germination rates of wild-type (WT), CaAIMK1-OX mutant, and CaAIMK1^K32N-OX plants on 0.5× Murashige and Skoog (MS) medium containing 0, 0.75, or 1.00 μM ABA. (B,C) Primary root elongation of WT and transgenic lines exposed to ABA. Representative images were taken (B) and the root length of each plant was measured 8 days after sowing (C). (D,E) Seedling development of WT, CaAIMK1-OX, and CaAIMK1^K32N-OX plants exposed to various concentrations of ABA. Representative photographs were taken 5 days after plating (D). Quantification of green cotyledons in WT and transgenic plants was performed 5 days after plating (E). Data represent the mean ± standard error values obtained after evaluating 72 seeds from three biological replicates. (F) Drought-sensitive phenotype displayed by CaAIMK1^K32N-OX plants. Three-week-old WT and transgenic plants were subjected to drought stress by withholding watering for 18 days and then re-watering for 2 days. Representative images were obtained before (left panel) and after (middle panel) drought stress and after 2 days of re-watering (right panel). Survival rates of plants after 2 days of re-watering are shown in parentheses. Data represent the mean ± standard error of three biological replicates, each evaluating 27 plants. Asterisks indicate significant differences between WT and transgenic lines (Student’s t-test; * P < 0.05, ** P < 0.01).