For the first time, seasonal changes in the content of total lipids (TLs) and phospholipids (PLs) were studied in fodder plants growing in Central Yakutia—a perennial cereal, smooth brome (Bromopsis inermis L.), and an annual cereal, common oat (Avena sativa L.). Both species have concentrated TLs and PLs in autumn under cold hardening. In addition, a significant increase in the content of fatty acids (FAs) of B. inermis was observed during the autumn decrease in temperature. The Yakutian horses, which fed on cereals enriched with nutrients preserved by natural cold (green cryo-fodder), accumulated significant amounts of 18:2n-6 and 18:3n-3, the total content of which in cereals was 75% of the total FA content. We found differences in the distribution of these two FAs in different tissues of the horses. Thus, liver was rich in 18:2n-6, while muscle and adipose tissues accumulated mainly 18:3n-3. Such a distribution may indicate different roles of these FAs in the metabolism of the horses. According to FA content, meat of the Yakutian horses is a valuable dietary product.

The lipid composition of two species of vascular plants, Equisetum variegatum Schleich. ex. Web. and E. scirpoides Michx., growing in the permafrost zone (Northeastern Yakutia, the Pole of Cold of the Northern Hemisphere), with average daily air temperatures in summer of +17.8 °C, in autumn of +0.6 °C, and in winter of −46.7 °C, was comparatively studied. The most significant seasonal trend of lipid composition was an accumulation of PA in both horsetail species in the autumn–winter period. Cold acclimation in autumn was accompanied by a decrease in the proportion of bilayer-forming lipids (phosphatidylcholine in the non-photosynthetic membranes and MGDG in photosynthetic membranes), an increase in the desaturation degree due to the accumulation of triene fatty acids (E. scirpoides), and an accumulation of betaine lipids O-(1,2-diacylglycero)-N,N,N-trimethylhomoserine (DGTS). The inverse changes in some parameters were registered in the winter period, including an increase in the proportion of “bilayer” lipids and decrease in the unsaturation degree. According to the data obtained, it can be concluded that high levels of accumulation of membrane lipids and polyunsaturated FAs (PUFAs), as well as the presence of Δ5 FAs in lipids, are apparently features of cold hardening of perennial herbaceous plants in the cryolithozone.

Lipids are the fundamental components of cell membranes and they play a significant role in their integrity and fluidity. The alteration in lipid composition of membranes has been reported to be a major response to abiotic environmental stresses. Seasonal dynamics of membrane lipids in the shoots of Ephedra monosperma J.G. Gmel. ex C.A. Mey. growing in natural conditions of permafrost ecosystems was studied using HPTLC, GC-MS and ESI-MS. An important role of lipid metabolism was established during the autumn-winter period when the shoots of the evergreen shrub were exposed to low positive (3.6 °C), negative (−8.3 °C) and extremely low temperatures (−38.4 °C). Maximum accumulation of phosphatidic acid (PA), the amount of which is times times greater than the sum of phosphatidylcholine and phosphatidylethanolamine (PC + PE) was noted in shoots of E. monosperma in the summer-autumn period. The autumn hardening period (3.6 °C) is accompanied by active biosynthesis and accumulation of membrane lipids, a decrease of saturated 34:1 PCs, 34:1 PEs and 34:1 PAs, and an increase in unsaturated long-chain 38:5 PEs, 38:6 PEs, indicating that the adaptation of E. monosperma occurs not at the level of lipid classes but at the level of molecular species. At a further decrease of average daily air temperature in October (−8.3 °C) a sharp decline of PA level was registered. At an extreme reduction of environmental temperature (−38.4 °C) the content of non-bilayer PE and PA increases, the level of unsaturated fatty acids (FA) rises due to the increase of C18:2(Δ9,12) and C18:3(Δ9,12,15) acids and the decrease of C16:0 acids. It is concluded that changes in lipid metabolism reflect structural and functional reorganization of cell membranes and are an integral component of the complex process of plant hardening to low temperatures, which contributes to the survival of E. monosperma monocotyledonous plants in the extreme conditions of the Yakutia cryolithozone.