Fluorescence and Photochemical Investigations of Phytochrome in Higher Plants
Figure 16
Two modes of light-induced phyA decline—with and without changes in the phy/phy equilibrium. Epicotyls of wild type pea and its point mutated phyA-3D species with alanine to valine substitution at position 194, A194V. Note that the decrease in the total phyA content in epicotyls of etiolated seedlings after saturating red illumination ( nm, 4 h) is followed by a shift in the phy/phy equilibrium towards the less light-labile phy form whereas even much more pronounced decline of in seedlings grown under far-red light ( 720 nm, I = 0.1 W m−2) is practically not accompanied by violation in the equilibrium. Note also a much lower effect of Rc and a much higher effect of FRc on the total phytochrome content in the case of the pea mutant suggesting that this mutation makes the photoreceptor less light-labile and more physiologically active. (From [87, 88]).
