Three Modes of Phytochrome-Mediated Responses Control the Expression of Lhcb1*2: VLFR, LFR, and HIR.
(A) The LFR and the HIR. GUS activity driven by the −752 to +67 Lhcb1*2 promoter of tobacco fused to gusA in transgenic seedlings of Arabidopsis exposed to hourly pulses of FR light, hourly pulses of R light, hourly pulses of R light immediately followed by FR light, or continuous FR light. Seedlings of the wild type (WT) and of the phyA-211 and phyB-9 mutants are included. Data are means ±se of four or five replicate samples. Double-headed arrows show the magnitude of LFR and HIR.
(B) The VLFR and the HIR. GUS activity driven by the −752 to +67 Lhcb1*2 promoter of tobacco fused to gusA in transgenic seedlings of Arabidopsis exposed to repeated pulses of FR light separated by intervals of darkness of the durations indicated. Data are means ±se of four replicate samples. Inset, detail of the effect of hourly pulses of FR light. Double-headed arrows show the magnitude of VLFR and HIR.