Comparative Studies on the Effect of Ammonia and Blue Light on the Regulation of Photosynthetic Carbon Metabolism in Higher Plants

Abstract

Ammonium salts have been shown to divert the photosynthetic carbon more towards the synthesis of amino acids in Chlorella [9, 10] and in the leaf cells and discs of higher plants [14, 15, 16]. Blue light has also been reported to have a similar effect on the synthesis of amino acids. It has been suggested that NH₄ brings about the increased synthesis of amino acids by the stimulation of pyruvate kinase [9, 10], while blue light through the activation of PEP carboxylase. Warburg et al. [19] first reported that catalytic amounts of blue light might be necessary to obtain high quantum yields of photosynthesis. The photoreceptor involved in the regulatory role of blue light on the carbon metabolism is presumed to be flavin or carotenoids from the action spectra [11, 18]. The present communication deals with the comparative study on the mechanism of action of NH₄ ⁺ and blue light in bringing about the regulation of the photosynthetic carbon flow, leading to the increased synthesis of amino acids in the leaves of higher plants.