Figure 4.

ABA responses of Col-0, 35S:RHA2a, rha2a, 35S:RHA2b, rha2b-1, and rha2a rha2b-1 plants in seedling growth. A, Sensitivity of seedlings to ABA. Four-day-old seedlings grown without ABA were transferred to a plate containing 20 μm ABA. The photographs were taken 11 d after the transfer. B, Measurement of taproot length. Taproot lengths of the seedlings in medium containing the indicated concentrations of ABA were measured (see “Materials and Methods”). Relative root growth compared with that on ABA-free medium is indicated. Data shown are means ± sd of three replicates. At least 30 seedlings per genotype were measured in each replicate. C, Quantification of lateral root number. D, Quantification of true leaf number. E, Measurement of seedling fresh weight. Seedlings were collected for measurement of fresh weight. Relative fresh weight compared with that on ABA-free medium is indicated. Asterisks in B to E indicate significant differences from the corresponding wild-type values determined by Student’s t test (* 0.01 ≤ P < 0.05, ** P < 0.01). At least three independent experiments were conducted, and similar results were obtained. [See online article for color version of this figure.]