Figure 1.

Seed germination is enhanced by external calcium. A, Effect of calcium on germination. Arabidopsis wild-type seeds sown on modified MS medium containing 0 or 5 mm CaCl₂ or 0 mm CaCl₂ supplemented with 10 mm EGTA were incubated at 4°C (in the dark) for 3 d and transferred to the growth chamber (22°C) for 36 (top) or 42 h (bottom) prior to analysis. Three biological replicates were performed, and representative images are shown. B, Quantification of germination percentage at various concentrations of external Ca²⁺. Seeds were sown on modified MS medium containing indicated amounts of CaCl₂ and scored for germination 36 h after incubation under the germination conditions. C, Effect of EGTA on germination. Seeds were sown on modified MS medium containing no CaCl₂ supplemented with 5 or 10 mm EGTA and scored for germination 42 h after incubation under the germination conditions. D, Time course quantification of germination at various amounts of external Ca²⁺. Seeds were incubated on the same medium as in A at 22°C for 24 to 60 h and scored for germination. Asterisk indicates the germination percentage at 36 h after incubation of the seeds under the germination conditions. E, Effect of Ca²⁺ channel blocker LaCl₃ on germination. Seeds were incubated on MS medium supplemented with indicated concentrations of LaCl₃ and scored for germination 42 h after incubation under the germination conditions. For the germination analysis in B to E, data from three independent replicates are shown; error bars indicate se of the mean. Bar = 0.5 mm.