RAP2.1 negatively regulates plant tolerance to cold and drought stresses. (A) Schematic structure of RAP2.1 mutants, rap2.1-1 and rap2.1-2. The black rectangle represents the RAP2.1 coding region with a single exon. Triangles represent the T-DNA insertions. (B) Northern blot analysis of the RAP2.1 gene in wild type (WT), rap2.1-1 and rap2.1-2 mutants after 12 h of cold treatment. (C) RAP2.1 negatively regulates cold tolerance in Arabidopsis. Representative results of a triplicate independent experiment are shown. (D) Electrolyte leakage from wild type, mutant, and transgenic plants after exposure to low temperature (4°C or 0°C) for 6 h. (E) Photographs are of representative plants with 48 h of rehydration after 8 h of drought treatment. Wild type (WT), rap2.1-1, rap2.1-2, and 35S:myc:RAP2.1 (line 5) are shown. Survival rates were determined for at least 40 plants per line. (F) Water loss rate measurement in the wild type, rap2.1 mutants and RAP2.1 overexpressing plants. Values shown are means of data taken from three independent experiments; error bars indicate SD.