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FLUORESCENCE OF PHYTOCHROME IN THE CELLS OF DARK‐GROWN PLANTS AND ITS CONNECTION WITH THE PHOTOTRANSFORMATIONS OF THE PIGMENT
Author(s) -
SINESHCHEKOV VITALY A.,
SINESHCHEKOV ALEXEI V.
Publication year - 1989
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1989.tb04114.x
Subject(s) - phytochrome , fluorescence , etiolation , pigment , photochemistry , chemistry , excitation , red light , optics , botany , physics , biology , biochemistry , quantum mechanics , organic chemistry , enzyme
Fluorescence of phytochrome is found in the cells of etiolated monocotyledonous and dicotyledonous plants. The red light‐absorbing form of phytochrome (P r ) fluoresces at 77 K with a yield 0.3±0.1 and maxima at 672–673 nm and 684–686 nm in the excitation and emission spectra, respectively. The emission is characterized by the sharp temperature dependence of its intensity, its high (∼ 40%) polarization, and the violation of the mirror symmetry rule. Connection of the fluorescence with P r photoreactions is followed in the interval 77–293 K. A P, photoproduct, lumi‐R, is fluorescent with maxima at 696 nm and 705 nm in the excitation and emission spectra; the far‐red light absorbing form of phytochrome (P fr ) is practically nonfluorescent. Three isochromic emitting P r species are present differing in their photochemical properties: P r1 and P r2 which phototransform irreversibly and reversibly at T 170 K into lumi‐R, and lumi‐R 2 , respectively, and P r3 which undergoes photoconversion only at T > 240 K. The activation energies of P r2 and P r3 photoreactions are evaluated to be 2.9–3.3 kJ/mol and 26 kJ/mol. Complex dynamics of changes of P r fluorescence and of the extent of its decrease in the photoconversion P r ? P fr in germinating pea and bean seeds suggests the existence of two P r pools one of which is incapable of P r ? P fr phototransformation. Thus, the developed fluorescent method of phytochrome assay and investigation in the cell revealing multiplicity of phytochrome states in vivo proves to be very sensitive (about 1 ng) and informative.