Effect of organic acids on the amino acid metabolism of rice seedlings.

Abstract

Effects of pyruvate, citrate, succinate and glycolate on the incorporation of 15NH4 and 15NO3 into amino acids and amides, and on the amino acid contents were studied by using the seedlings of Norin No. 41 of rice. 1. Effect of organic acids on the incorporation of 15N from 15NH4Cl or Na15NO3 into amino acids and amides (Figs. 1 and 2). In the root, glutamic acid in 15NH4-feeding case and glutamine in 15NO3-feeding one were the most strongly labelled. The incorporation of 15N into amino acids and amides tested was decreased by the organic acid treatments in both cases of ammonium and nitrate. In the top, glutamine, glutamic acid and aspartic acid were relatively strongly labelled with 15N from both the 15NH4- and 15NO3-feedings. The effect of organic acids on the incorporation of 15N into amino acids and amides was decreased in the 155NO3-feeding, but it was not found in the 15NH4-feeding. In the endosperm, the incorporation of 15NH4 into glutamine was increased by the treatment with organic acids. 2. Effect of organic acids on the contents of amino acids and amides (Tables 2, 3, 4 and 5). In the root, the contents of amino acids and amides were increased by the treatment with organic acids in the NH4-feeding, but not in the NO3-feeding. In the top, the amounts of aspartic and glutamic acid were increased by the organic acid treatments in the NH4-feeding, but no the remarkable differences on the contents of amino acids and amides were found in NO3-feeding. In the endosperm, the effects of organic acid treatments to produce these nitrogenous compounds scarcely were found.