A Rapid Phytochrome-dependent Reduction of Nicotinamide Adenine Dinucleotide Phosphate in Particle Fraction from Etiolated Bean Hypocotyl.

Several different biochemical changes in plant cells are controlled by the phytochrome system (4), and the metabolism related to nicotinamide nucleotide coenzymes had recently been reported to be phytochrome-dependent by some workers (1, 8, 11). Fujii and Kondo (3) observed a red light-activated increase of NADPH level in node tissues of oat. Hitherto, little has been known about the intracellular localization of phytochrome. Gordon and Surrey (6) have suggested that mitochondria contain phytochrome, since the rate of oxidative phosphorylation in mitochondria isolated from rat liver was affected by red and far red irradiations. This result has failed to be confirmed (7). In 1959, Forti et al. (2) reported evidence of the existence, in pea stems, of glucose-6-P oxidizing particles which sedimented at lower centrifugal forces than did true mitochondria, but Ragland and Hacket (10) were unable to find any evidence for special glucose-6-P oxidizing particles that were distinct from typical mitochondria. The aim of the present investigation, therefore, was to examine the possibility of whether the red and far red reversible effect on the NADPH formation present is detectable in a low speed sedimentary particle fraction prepared from etiolated bean hypocotyl tissues.