Fig 1.
Expression cloning of rice CaS and Arabidopsis CaS using calcium imaging.
HEK293 cells were transiently transfected with empty vector, pcDNA3-CAS, or pcDNA3-OsCAS. The cytosolic Ca2+ status was analyzed using Fura-2-based Ca2+ imaging after treatment with 0.l mM and 2.5 mM extracellular Ca2+. Elevated relative calcium concentrations are indicated by an increased ratio of Fura-2 emission at 340 versus 380 nm wavelength excitation (see color bar). Arrows show cells with CICI (Ca2+ o-induced [Ca2+]i increases).
Fig 2.
Detection of gene expression in transgenic plants by real-time PCR.
Col-0 is the wild type; L1, L2, L3, and L4 represent OsCAS transgenic plants under the control of the CaMV 35S promoter; and Salk is the T-DNA insertion mutant. Mean and SE values were determined using at least three independent experiments. Significant differences from Col-0 control plants after drought treatment were determined by the t-test. * p < 0.05 and ** p < 0.01.
Fig 3.
[Ca2+]ext-induced stomatal closure in mutant plants and transgenic lines.
Stomatal aperture was calculated as the ratio of stomatal width to stomatal length. Each value is the mean of three independent measurements, and the error bars indicate SD. Significant differences from Col-0 control plants (No treatment, 2 mM CaCl2 treatment) after drought treatment were determined by the t-test. * p < 0.05 and ** p < 0.01.
Fig 4.
Drought stress tolerance of OsCAS transgenic plants.
A. Plant growth under well-watered conditions. B. Plant growth under drought stress for 21 days. C. Plant re-watering treatment. In images A, B, and C, the first line of plants are OsCAS transgenic type; the second line of plants are Salk; and the third line of plants are wild-type Col-0.
Fig 5.
Free proline content, MDA content, and RMP in Col-0, Salk, and L3 after drought treatment.
Each bar represents the mean from three replicates ± SD. Significant differences from Col-0 after drought stress were determined by the t-test. *p < 0.05 and**p < 0.01.
Fig 6.
Chlorophyll fluorescence of Col-0, Salk, and L3 under normal and drought stress conditions.
Chlorophyll fluorescence of the control was measured under normal conditions. Values represent the mean ± SD (n = 3, independent experiments). Values of ETR (A), Y(II) (B), Y(NPQ) (C), and Y(NO) (D) in the three lines.