Seasonal and daily dynamics of the nitrogen-containing compounds in the leaves of <i>Hylotelephium triphyllum</i> in the taiga zone of the European North-East

Abstract

The seasonal and daily dynamics of the content of nitrogen-containing compounds in the leaves of Hylotelephium triphyllum plants was studied. The maximum content of total nitrogen, soluble protein and free amino acids in the leaves was observed in the regrowth phase, followed by their reduction towards the end of the growing season. The daily dynamics was characterized by a high content of free amino acids and a low content of soluble protein in the morning hours. In the leaves of H. triphyllum , 23 free amino acids and 2 amides were found. The seasonal and daily dynamics of free amino acids was determined by the content of glutamine and glutamic acid. 4 non-proteinogenic amino acids were found: -aminobutyric, -alanine, ornithine, citrulline. The total proportion of non-theeinogenic amino acids increased with the aging of the leaves from 0,6% of the sum of amino acids during regrowth to 5,8%, in the fruiting phase, which corresponded to a decrease in the content of soluble protein in them. Seasonal and daily dynamics of non-theeinogenic amino acids was determined mainly by -aminobutyric acid. Alanine and -aminobutyric acid were predominated among the amino acids as an indicator of stress. It is assumed that -aminobutyric acid contributes to the regulation of acidity of cell sap in the leaves of H. triphyllum . At low air and soil humidity (flowering phase), the acidity of the cell sap significantly correlates with the content of free amino acids in the leaves.