BL-induced increase in [Ca²⁺]_c (Δ[Ca²⁺]_c, the difference between [Ca²⁺]_c in the dark before illumination and the BL-induced peak in [Ca²⁺]_c)in leaves of WT plants, phot1 and phot2 mutants, and phot1 phot2 double mutants and relative contributions of phot1 and phot2 to the BL responses. (A and B) Δ[Ca²⁺]_c in leaves of Ler plants and a phot1 mutant (A) and those in leaves of WS plants and phot2 and phot1 phot2 mutants (B) at various fluence rates of BL. (C and D) Relative contributions of phot1 (C) and phot2 (D) to the BL-induced Δ[Ca²⁺]_c. The contributions of phot1 in the presence and absence of phot2 were calculated as the percent difference in Δ[Ca²⁺]_c between phot1 and Ler (i.e., the results in A) and between phot1 phot2 and phot2 (results in B), respectively. The contribution of phot2 was calculated as the percent difference in Δ[Ca²⁺]_c between phot2 and WS. The vertical bars indicate the standard error of 5–20 independent experiments. * and **, significantly different from the data in the WT plant and the phot2 mutant, respectively (P < 0.05).

Effects of inhibitors on BL-induced Δ[Ca²⁺]_c in the WT plants and phot1 and phot2 mutants. A leaf, treated with each inhibitor in the dark, was irradiated with 1 μmol·m^-2·s^-1 of BL. Effects of 5 mM CoCl₂ (A), 100 μM nifedipine (B; 0.4% DMSO was used as the control), 10 μM neomycin (C), and 10 μM U-73122 (D; 10 μM U-73343, an inactive analogue, was used as the control) are shown. The vertical bars indicate the standard error of 3–18 independent experiments.

Immunodetection of HA-PHOT1 and -PHOT2 from inner membrane-rich (IM) and PM-rich (PM) fractions isolated from leaves of HA-PHOT1 and -PHOT2 transformants, respectively. The proteins (3 μg in each lane) were separated by SDS/PAGE. Epitope-tagged PHOT1 and PHOT2 were detected as slightly larger bands than predicted molecular masses of phot1 (112 kDa) and phot2 (102 kDa), respectively.