Figure 4.

Overexpression of CAR1 Leads to Enhanced ABA-Mediated Inhibition of Seedling Establishment and Shoot Growth.

(A) Photographs of the Col wild type, the hab1-1abi1-2 ABA-hypersensitive mutant (Saez et al., 2006), and two CAR1-overexpressing (OE) lines (#11 and #16) grown for 4 d on MS medium either lacking or supplemented with 0.3 μM ABA.

(B) Quantification of ABA-mediated inhibition of seedling establishment of the Col wild type compared with the hab1-1abi1-2 double mutant and two CAR1-overexpressing lines. Approximately 100 seeds of each genotype were sown on MS plates lacking or supplemented with 0.5 μM ABA and scored for the presence of green expanded cotyledons 7 d later. The photographs show representative seedlings removed at 7 d from MS plates lacking or supplemented with 0.5 μM ABA and rearranged on agar plates.

(C) 35S:CAR1 lines show enhanced sensitivity to ABA-mediated inhibition of vegetative growth. Photographs were taken of the Col wild type, the hab1-1abi1-2 double mutant, and two CAR1-overexpressing lines grown for 12 d on MS medium lacking ABA or 21 d in medium supplemented with 0.5 μM ABA.

(D) Quantification of fresh weight after 21 d of growth in medium lacking or supplemented with 0.5 μM ABA.

Asterisks in (B) and (D) indicate P < 0.05 (Student’s t test) when comparing data of 35S:CAR1 lines and the hab1-1abi1-2 mutant with Col wild-type plants in the same assay conditions.

[See online article for color version of this figure.]