Figure 2.

The overexpression of AREB-1 leads to a classical drought-tolerance phenotype under severe water deprivation. To simulate a closed field drought, 5-week-old A. thaliana WT and homozygous lines overexpressing AREB-1 were exposed to water deprivation for 30 days. (A) During drought, the transgenic lines display the classical phenotype of drought tolerance, exhibiting a low ratio of leaf yellowing and curliness, reinforced by the green, healthy phenotype of plants. The WT plants displayed, in addition to leaf yellowing, the production of defensive metabolites triggered by severe drought stress, indicated by purple-colored leaves. After recovery, AREB1-OX plants were almost fully recovered and only 45–50% of the WT plants recovered. (B) Relative water content (RWC) during drought. All pots were filled with 98 g of moist soil and watered normally until drought stress. During water deprivation, the pots were weighed, and the RWC was calculated according to the initial weight. The RWC values were normalized to the value at 100% RWC of the control groups. (C) Biomass loss ratio. The regularly watered plants were randomly distributed on trays and analyzed at intervals of 10 days under 30 days of water deprivation. After drought stress, plants were re-watered for 1 week to calculate the plant survival ratio. Control plants were normally watered during the stress period, and biomass loss was set as 0%. Values represent the increasing biomass loss as compared to 0% of the control group. All analyses were conducted with 3 biological and 2 technical replicates composed of a pool of 9 plants. The bars indicate 5% standard error, and asterisks indicate t-test statistical significance under 95% confidence.