Carbon Dioxide Fixation by Barley Roots

Abstract

The non-volatile, 80 per cent.ethanol-soluble products of fixation have been investigated in excised roots, using C 14O2 and radiochromatography. The main radioactive compounds separated were malic, citric (or iso -citric), aspartic, and glutamic acids, asparagine and glutamine. Less activity was present in serine, tyrosine, α-ketoglutaric acid, and alanine, and in a number of unidentified compounds. The uptake of C 14O2 was inhibited by virtually anaerobic conditions. From the above observations it is considered likely that C 14 is transformed through the reactions of the tricarboxylic acid cycle. C 14 in the soluble fraction was markedly increased by maintaining the root material in water rather than in a nutrient solution prior to exposure to C 14O2 This increase was chiefly in malic acid.