Figure 9.

Stress tolerance of the ndufs4 mutant. A, NBT stain for superoxide in leaves. Three examples are shown for each ecotype, and the average amount of superoxide was estimated by quantifying the coloration (n = 20). B, In vitro analysis of root growth under stress conditions. Data are expressed as the ratio between the root length of plants grown under control conditions and those of plants grown under stress conditions (n = 20). Comp, Complemented mutant. C, Drought stress assay in individual pots. After 10 d of withholding water from 40-d-old plants, the viability was assessed visually (Exp. 1; a representative image is shown) and by monitoring chlorophyll fluorescence (Exp. 2). D, Drought stress assay with plants staggered (the mutant was sown 10 d before Col-0) and grown in the same pot under normal conditions. The last watering occurred at day 28 after transfer to soil. A photograph was taken every 3 d, and the soil water content was measured.