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Changes in the fatty acid composition of neutral lipids in buds in the winter-spring period (January-May) were studied in silver birch (Betula pendula Roth) growing under the notably different natural and climatic conditions of Karelia and Yakutia. In this period, the apical meristem develops inside the bud. The study showed that irrespective of the geographical location, neutral lipids in silver birch buds contained high levels of unsaturated fatty acids. Their content declined as the air temperature rose, but the double bond index in buds of the trees growing in Karelia remained almost unchanged, whereas in Yakutia it even increased somewhat. At the same time, the prevalent neutral lipid fractions in Karelia were di- and trienoic fatty acids, and in Yakutia it was mono- and dienoic acids. Awakening from exogenous dormancy in the period in question was accompanied by certain changes in the activity of acyl-lipid desaturases: in Yakutia, the oleoyl- and linoleoyl-desaturase ratios in buds increased from January towards May, while in Karelia a minor rise in the ratios was observed only in April. The high stearoyl-desaturase ratios, especially in Yakutia, are probably explained by the functional role of neutral lipids as energy and/or substrate depots, which are utilized not only in the processes of bud adaptation to low temperatures but also in the formation of primordial structures in buds. Our data also indicate that the variation of the indices that represent the specific features of neutral lipids in silver birch buds was mostly controlled by the physiological status and the development phase of embryonic organs formed therein, whereas the timing of the phases, as well as the composition and content of fatty acids – by the local environmental and climatic conditions
Ветчинникова et al. (Tue,) studied this question.