The phytochrome mediated enhancement of peroxidase activity in maize leaves was repressed by inhibitors of cytoplasmic protein synthesis, whereas inhibitors of RNA and organelle protein synthesis were ineffective. Continuous far-red light had no effect on the DNA level in the leaves, but it increased the RNA level after a lag of 2 hr. Under continuous far-red light the total content of polyribosomes also increased after a lag of 2 hr. Isolated polyribosomes from far-red grown plants showed an enhanced rate of the in vitro incorporation of amino acids into proteins as compared to dark grown plants. These results indicate that the phytochrome regulation of peroxidase activity occurs at the translational level.
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