Stress tolerance of Arabidopsis plants overexpressing BdCBF1 gene. The BdCBF1 cDNA was transformed into Arabidopsis Col-0 plants under the control of the CaMV 35S promoter. Two independent transgenic lines were included in the assays. Plants were grown on MS-agar plates for either one (A and C) or two weeks (B) before stress treatments. In (A) to (C), measurements of 30–35 plants were averaged and statistically treated using the Student t-test (*P < 0.01). A. Freezing tolerance assays. Plants were exposed to -8°C for 5 h and allowed to recover at 23°C for 10 days. Rosette leaves were for the measurements of chlorophyll contents. B. Drought tolerance assays. Plants were exposed to drought stress conditions without watering for 12 days and rewatered for 3 additional days before the assays. C. Salt tolerance assays. Plants were transferred to MS-agar plates containing 150 mM NaCl and further grown for 5 days. Rosette leaves were for the measurements of chlorophyll contents. D. Expression of CBF target genes in 35S:BdCBF1 transgenic Arabidopsis plants. Transcript levels were determined by qRT-PCR. Biological triplicates were averaged and statistically treated using the Student t-test (*P < 0.01). Bars indicate standard error of the mean.