PLANT PHYSIOLOGY , Vol 102, Issue 4 1237-1241, Copyright © 1993 by American Society of Plant Biologists
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ENVIRONMENTAL AND STRESS PHYSIOLOGY |
Phytochrome Control of the Development of Ascorbate Oxidase Activity in Mustard (Sinapis alba L.) Cotyledons
R. Hayashi and Y. Morohashi
Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183, Japan
The activity of ascorbate oxidase (AOX) in mustard (Sinapis alba L.)
cotyledons was markedly increased by irradiation with continuous far-red
light. The involvement of phytochrome in this light-mediated response was
demonstrated by red/far-red reversibility experiments. To determine
immunochemically the contents of AOX in cotyledons, the antibody against
the enzyme was raised in a rabbit. However, the antiserum was not
monospecific to AOX; it also recognized glycoproteins. To remove antibodies
that are specific to a carbohydrate moiety of glycoproteins, the anti-AOX
antiserum was applied to a horseradish peroxidase-conjugated Sepharose
column. By using the antibodies that were not retained in the column, the
changes in the content of AOX were followed. Western immunoblot profiles
revealed that the content of AOX protein in cotyledons notably increased
after continuous far-red light treatment. Pulse-labeling experiments
indicated that the synthesis of AOX protein occurred in the cotyledons.
These results are in good agreement with the hypothesis that
phytochrome-mediated increase in AOX activity is accompanied by the
synthesis of the enzyme.
