Fluorescence and Photochemical Investigations of Phytochrome in Higher Plants
Figure 11
Low-temperature (85 K, nm) fluorescence emission spectra of phyB in the Pr form in etiolated epicotyls of phyA-deficient, fun1-1, pea mutant (a) and of Arabidopsis phyB expressed in transgenic potato (DARA12 strain, lower parts of etiolated stems after red-light-induced destruction of phyA, nm, 3.5 h, 293 K) (b): in the state when all the pigment is in the Pr form, that is, after darkness or far-red (720 nm) saturating illumination at 293 K converting Pfr into Pr; after saturating illumination with actinic red light (633 nm, 85 K) to reach the equilibrium between Pr and lumi-R, and after thawing the samples at 273 K, illumination with saturating red (633 nm) light to convert Pr into Pfr and freezing again at 85 K. Insert in (a) is the mean of the experimental spectra of etiolated epicotyls with the bars indicating the standard error. Curve 4 in (b) is the low-temperature excitation spectrum of Pr ( 720 nm), corresponding to the emission spectrum 1. Note the lack of the effect of the red-light actinic illumination on the emission spectrum at 85 K (no, or low, photochemical Pr conversion into lumi-R, ) and relatively low extent of the PrPfr conversion ( 0.5). (From [39, 40]).
