Effect of Auxin on Fatty Acid Composition and Activity of Acyl-Lipid Desaturases in Seedlings of Spring Wheat Triticum aestivum L.

The effect of exogenous auxin on changes in the fatty acid composition of the total lipids of leaves and roots of spring wheat (Triticum aestivum L.) seedlings was studied. It was found that the diversity of fatty acids in vegetative organs (leaf and root) depended not only on the concentration of auxin, but also on the donor of nitric oxide (N₂ and NO₃). With an increase in the concentration of exogenous auxin, there was an increase in microviscosity and a decrease in the permeability of membranes of vegetative organs of wheat, which was confirmed by a decrease in the double bond index (DBI). At the same time, there was an increase in the concentration of saturated fatty acids (palmitic and stearic), which were used as precursors for the formation of very long-chain fatty acids (VLCFA). It was found that exogenous auxin led to an increase in the total content of VLCFA in leaves with a deficit (8.4%) and an excess of NO donors (12.3%). The introduction of exogenous auxin eliminated significant differences in desaturase activity in wheat roots at different levels of nitric oxide donors. It was suggested that the biosynthesis of docosadienoic acid (C_22:2) in leaves is one of the key stages in the formation of the adaptive response of cell membranes to the effects of abiotic stresses during plant ontogenesis. An increase in the NO level promoted the movement of auxin from the roots to the shoots, which can serve as a regulator of the activity of elongases and desaturases during the synthesis of VLCFA.