LIPID FATTY ACID COMPOSITION IN MALE INFLORESCENCES OF BETULA PENDULA ROTH IN SPRING
It is demonstrated that the phenological phase transition in Betula pendula Roth in spring is accompanied by substantial changes in the fatty acid composition of some lipid fractions in male inflorescences. Thus, at the beginning of their flowering (shedding of outer cover), when low positive or negative temperatures returned, total unsaturated fatty acids (FA) prevailed over saturated FA in all lipid fractions, especially in membrane lipids, where the content of unsaturated fatty acids was double that of saturated FA. As positive temperatures piled up and the plant was in the phase of staminate inflorescence loosening, there was, on the contrary, an accumulation of saturated fatty acids in storage (neutral) lipids (up to 70 % of total fatty acids or more) and glycolipids (up to 50 % of total fatty acids or more). In phospholipids, on the other hand, the ratio of fatty acids was steadily in favor of unsaturated FA, chiefly linoleic acid (up to 65 % of total fatty acids or more), irrespective of the phase of male inflorescence development. Glycolipids in silver birch were dominated by linolenic acid (50 % of total fatty acids and more). It is hypothesized that two interrelated strategies are realized in the lipid metabolism of silver birch male inflorescence in spring, targeted at successful progress through the flowering phase and formation of fertile pollen, on the one hand, and at safeguarding the male hametophyte against spring frosts, which often return in the species range in late April - early May, on the other.