A comparative analysis of the fatty acid (FA) composition of lipids in the calluses and needles of Scots pine (Pinus sylvestris), white spruce (Picea pungens), Korean pine (Pinus koraiensis), and Sibe

Evergreen plants in permafrost ecosystems survive unfavorable autumn cooling and extremely low winter temperatures by maintaining optimal physiological activity of tissue cell membranes. To some extent, these features are due to the properties of shoot lipids performing a number of functions during adaptation. Sterols (STs) play a key role in regulating the fluidity and permeability of plant membranes (phytosterols) with a wide structural diversity. The composition of neutral lipids, STs, and fatty acids (FAs) in shoots of the evergreen shrub Ephedra monosperma growing in the Botanical Garden cryolithozone was first studied with HPTLC-UV/Vis/FLD and GC-MS. Twenty FAs were found, from C14:0 to C23:0; they included mono-, di-, tri-, and tetraene FAs. The high content of β-sitosterol among other ∆-5 sterols and an increased amount of C18:2(∆9,12) linoleic acid in lipids composition during the autumn–winter period was found to play an important role in the adaptation of ephedra shoots to the autumn–winter period, providing the cell membrane with greater plasticity, fluidity, and flexibility. The important role of diene linoleic fatty acid C18:2(∆9,12) in ephedra shoot lipids in the processes of low-temperature adaptation was shown.

Composition of phospholipids was examined in embryogenic and non-embryogenic cell lines of Siberian larch (Larix sibirica Ledeb.). Significant differences in the content and composition of phospholipids were revealed between the cell lines. Phosphatidylcholines (PC) and phosphatidylethanolamines (PE) were predominant phospholipids in embryogenic cell lines, whereas non-embryogenic cell lines featured a high content of phosphatidic acid (>64% of total phospholipids). The PC/PE ratio known to characterize the membrane structure and function was 1.4–3.8 times higher for embryogenic cell lines than for non-embryogenic lines; this was probably caused by the involvement of these phospholipids in tissue differentiation. The content of phosphatidylinositols differed significantly for embryogenic and non-embryogenic cell lines, where it equaled to 0.50–1.06 and 0.17–0.34 mg/g dry wt, respectively. The observed variations in the composition of phospholipids between the cell lines with different embryogenic potential provide evidence for the important role of these lipids in embryogenesis at the stage of embryo formation.

Mowing the plant shoots under hot, sunny, and dry conditions severely traumatizes the entire vegetative body, and the overall life cycle of the plant is altered. The purpose of the present research was to investigate the effects of mowing and drying on lipids, fatty acids (FA), sterols, and the systemic responses in leaves of plant material at three time points (24 h, 72 h, and leaves of new shoots after traumatic mowing in summer (1 July) and those subjected to cold hardening by autumn temperatures in September (aftergrass)) were analyzed for the first time. The leaves of five species of herbaceous plants growing in permafrost ecosystems were analyzed by HPTLC and GC-MS. It was established that fatty acids in the tissues of aftergrass leaves were characterized by higher values of the n-6/n-3 ratio than in summer grasses. It was demonstrated that exposure of leaves for 72 h in natural conditions in summer and at low temperatures in autumn in leaves of aftergrass resulted in significant changes in the composition of membrane phospholipids. The obtained findings indicate that leaves of aftergrass are the most valuable plant raw material in terms of FAs and phytosterols content compared to hay mowed in summer.

The cell lines of Siberian larch (Larix sibirica Ledeb.), possessing different embryogenic potential, were studied. Qualitative and quantitative content of sterol components was comparatively analyzed in their tissues with the help of gas chromatography-mass spectrometry. Significant differences in these parameters were found between both groups of the lines in fractions of free sterols and their esters. In addition to sterol compounds, squalen, which is a triterpenic intermediate in sterol biosynthesis, was revealed. Of free sterols, β-sitosterol, campesterol, isofucosterol, and stigmasterol dominated in the embryogenic lines, while β-sitosterol, campesterol, and stigmasterol in nonembryogenic ones. The campesterol concentration was 1.3–1.9 times higher in the embryogenic than nonembryogenic lines. Since campesterol is a precursor of brassinosteroids, it is likely that its level is high due to an embryogenic state of these cell lines. Only the embryogenic lines contained appreciable amounts of isofucosterol. The fraction of sterol esters exhibited wider component diversity in the nonembryogenic than the embryogenic lines. In all the cell lines, among the identified sterol esters, the substances without double bonds, bearing, as a structural fragment, a sterane core—perhydrocyclopenta[a]phenanthrene—were the most abundant. Their content ranged from 52 to 71% of the total amount of sterol esters. The revealed differences in the compositions of sterols and their esters, between the L. sibirica cell lines with different embryogenic potential, witness to the considerable rearrangements in sterol metabolism in the course of embryogenesis. The line-specific differences may indicate the involvement of these metabolites in formation of embryos.

The prevalence of coniferous trees in the forest landscapes of northeastern Siberia is conditioned by their high frost resistance. The Kajander larch (Larix cajanderi Mayr), which can survive under natural conditions (down to −60 °C) in the cryolithozone of Yakutia, is the dominant forest-forming species. We hypothesise that our study using HPTLC–UV/Vis/FLD, TLC–GC/FID, and GC–MS methods of seasonal features of the lipid profile of Kajander larch tissues will bring us closer to understanding the mechanisms of participation of lipid components in the adaptation of this valuable tree species to the cold climate of the cryolithozone. Rare delta5-unsaturated polymethylene-interrupted fatty acids (∆5-UPIFA) were identified in the fatty acids (FAs) of L. cajanderi shoots, including 18:2(Δ5.9) (taxoleic), 18:3(Δ5.9.12) (pinolenic), and 18:4(Δ5.9.12.15) (coniferonic). It was found that the content of ∆5-UPIFA in L. cajanderi shoots markedly increased (1.5-fold, representing up to 23.9% of sum FAs) during the autumnal transition of trees to dormancy. It was observed that the ranges of low temperatures experienced during the prolonged winter period primarily determined the structural diversity of membrane lipids and their constituent FAs during the cold adaptation of L. cajanderi. The results obtained can be used for the selection of molecular markers of cold tolerance in woody plants, including fruit trees.