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Studies on Greening of Etiolated Seedlings II. Leaf Greening by Phytochrome Action in the Embryonic Axis
Author(s) -
GREEF J. A.,
CAUBERGS R.
Publication year - 1973
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1973.tb01153.x
Subject(s) - etiolation , greening , phytochrome , phaseolus , photosynthesis , photomorphogenesis , biology , respiration , botany , far red , biophysics , embryonic stem cell , pigment , biochemistry , microbiology and biotechnology , chemistry , red light , arabidopsis , mutant , ecology , organic chemistry , gene , enzyme
We could demonstrate that greening of primary bean leaves in etiolated seedlings of Phaseolus vulgaris cv. Limburg can be controlled by a selective light‐pretreatment of the embryonic axis. This light‐induced interorgan synergism proved to be a phytochrome‐mediated process. The red/farred photoreversible effect on the embryonic axis seems to be primarily linked to changes in the energy metabolism of the primary leaves. Phototransformation of the protochlorophyll present and pigment synthesis are very dependent upon an adequate supply of biochemical energy. When the embryonic axis is selectively pre‐exposed to red light for a short time, respiration is markedly enhanced in the leaves and photosynthesis starts immediately upon illumination of the etiolated leaves after an incubation period of optimal length in the dark. The stimulatory effect of the red pretreatment on leaf respiration and photosynthetic capacity could be abolished to the level of the dark controls by a subsequent far‐red irradiation on the embryonic axis. It is therefore postulated that phytochrome plays a regulatory role in interorgan cooperation. The metabolic changes involved in photomorphogenesis of etiolated seedlings are closely related to changes in energy production. Our data indicate that the primary act of phytochrome becomes operative at the biochemical level by its directional influence on the energy balance of the cell and coordinates the use of metabolic energy within a tissue and between organs.