Phytochrome-mediated development of glycine oxidation by mitochondria in cucumber cotyledons

The development of glycine oxidation activity in mitochondria in etiolated cucumber ( Cucumis sativus L., cv. Shinfushinari) cotyledons is regulated by phytochrome. This conclusion is based on two lines of evidence. 1. The oxidation activity was increased by continuous illumination of far-red light. 2. It was also increased by brief red light pulses, the effect of which was reversed by brief far-red light pulses. The light-induced increase in glycine oxidation and in glycine decarboxylase (EC 2.1.2.10) activity in the cotyledons was inhibited by cycloheximide, but not by chloramphenicol. While glycine oxidation activity continued to increase during light-illumination for 20 h, malate oxidation activity increased for 6 to 8 h after illumination and decreased thereafter. This transient increase in the activity of malate oxidation was also induced by red light pulses and the effect of the red light was reversed by far-red light pulses.