Fractional and Fatty Acid Composition of Lipids from the Bud Parts of Plants of the Betula L. Genus by Opening Phases

Abstract

In plants of the genus Betula L. with morphological characteristics of downy birch B. pubescens, silver birch B. pendula, and Karelian birch B. pendula var. carelica in bud fragments, according to the phases of their blossoming, growth and moisture indicators were studied as were the content and composition of fatty acids (FA) of individual fractions of total lipids (TL). Fractions of neutral lipids (NL), glycolipids (GL), and phospholipids (PL) were isolated from TL using chloroform, acetone, and methanol, respectively. Growing rudimentary leaves were distinguished by increased weight and moisture content compared to scales and stipules. In the embryonic leaves, in comparison with other fragments of buds in the phases of blooming, a high absolute content of TL in phase I and a drop in the level of TL in other phases, a significant absolute accumulation of NL and PL by phase III and use in phase IV with the accumulation of GL in this phase, a high level of unsaturated fatty acids (UFA) of TL and their individual fractions during the study period, an increase in the level of linolenic acid (C_18:3) in the composition of PL and GL to phase IV, and an increase in the relative content of palmitic acid (C_16:0) in the composition of GL by phase III and a decrease in its level in phase IV were noted. The fatty acid composition of the TL fractions of fragments of opening birch buds were represented predominantly by UFAs (up to 88% of the total FAs). The main share of UFAs was C_18:3 and linoleic (C_18:2) (up to 55 and 47% of the total FAs, respectively), and C_16:0 predominated (up to 42%) in saturated FAs. In three birches, during the development of buds according to the phases of blossoming in their individual fragments, both in the TL and in all fractions of the TL, the relative content of C_18:2 decreased with an increase in the composition of GL and PL: C_18:3. In these birches, which differ in morphological characteristics, distinctive features of the lipid composition are revealed mainly in the scales.