Natalia V. Semenova

The changes in the fatty acids (FAs) composition and the activity of acyl-lipid desaturases in lipids of needles formed on perennial shortened shoots—brachyblasts and annual elongated shoots—auxiblasts of Siberian larch ( Larix sibirica Ledeb.) during their spring–summer–autumn growth and development in the Irkutsk region were studied. It was found that in the lipids of brachyblast needles at the leaf-out stage (early May), the unsaturation indices (U/S and DBI) are characterized by the lowest values (0.16 and 0.25, respectively). With an increase in air temperature, they increase significantly and become close in value to those of auxiblast needles, regardless of the development phase of the latter (about 3.0 and 2.0 U/S and DBI, respectively). During the growing season, the ODR index was the highest and relatively stable in the needles of both shoot types. In the shoot stems, its values were lower but equal to the SDR index (0.75–0.85), which gradually increased from June to October. Significant differences were observed in the LDR index, which was at least four times higher in the needles than in the stems. Among the rare FAs characteristic of conifers, pinole FA stands out; its content in auxiblast stems varies from 10 to 16%, while in the needles of both shoot types, its values are half as much. The combined data revealed both similarities and differences in the FAs composition and activity of acyl-lipid desaturases in the needles of different shoot types—brachyblasts and auxiblasts. At the same time, their FAs composition differs significantly from that of auxiblast stems, which is likely due to different but complementary functions: needle lipids promote active photosynthetic function, while auxiblast stem lipids facilitate successful preparation for survival in the low, subzero temperatures of the upcoming winter.

The phytopathogenic bacterium Pectobacterium carotovorum (Pcc) infects a wide range of crop plants and causes substantial economic losses. The authors of this study previously demonstrated that the selenium–arabinogalactan nanocomposite (Se/AG NC) is capable of mitigating the negative effects of infection of soybean seeds with Pcc during germination and can influence physiological and biochemical factors in the seedlings. This study investigated changes in the membrane fatty acid (FA) profile of soybean seedlings grown under different treatments and in control using chromatography–mass spectrometry (CMS). The soybean seed treatments included the following: (1) infection by Pcc alone; (2) nanopriming with Se/AG NC alone; and (3) infection by Pcc followed by nanopriming with Se/AG NC. The infection was performed by soaking seeds in a bacterial suspension. Nanopriming was performed by placing the seeds in an aqueous solution of Se/AG NC (6.25 µg/mL) with a Se concentration of 0.000625%. Then, the seeds were germinated over 5 days in the darkness at 25 °C. The FA profile of soybean seeds was characterized by 13 FAs dominated by linoleic (LA), linolenic (LNA), oleic (OA), palmitic (PA) and stearic (SA) acids. Se/AG NC nanopriming had no influence on the FA profile of soybean seeds. A unique FA profile of soybean seedlings was demonstrated. It consisted of 18 FAs containing 12 to 20 carbon atoms. The following FAs were dominant in the control samples: PA (28%), LA (32.8%), LNA (18.6%), and SA (7.5%). Pcc infection of the seeds amplified the content of unsaturated FAs. Nanopriming of the seeds with Se/AG NC had an obvious influence on the seedling FA profile. Treatment of soybean seeds infected with Pcc using Se/AG NC caused weakening of the detrimental effects of the pathogen, while giving the possibility to maintain soybean seedlings’ FA profile at the control level. Transcript levels of the GmFAD8-2 gene encoding the membrane-bound omega-3 FA desaturase (FAD) were elevated for soybean seedlings after both Pcc and Se/AG NC seed treatment processes. The FA double-bond index (DBI) grew under the influence of seed infection and dropped under other treatments. Nanopriming of the seeds with Se/AG NC effectively reduced stress in Pcc-infected plants, as evidenced by analysis of the abscisic acid (ABA) content. Variations in the membrane FA composition under nanopriming with Se/AG NC may be one of the forms of its phytoprotective effect.

Background. Research studies of the composition and content of carbohydrates in fruits of the hybrid varieties Malus baccata (L.) Borkh. and Malus domestica Borkh., which are widespread in cold climates, are important both from a fundamental point of view - for assessing the inheritance of these traits in hybrid generations, and from a practical point of view - as a marker for selecting hybrids with improved taste qualities. However, a detailed analysis of the carbohydrate content of these hybrids is poorly studied. Purpose. Comparative analysis of the carbohydrate composition in the fruit tissues of M. baccata (L.) Borkh. and its hybrid varieties with M. domestica Borkh. Materials and methods. The study of the quantitative and qualitative composition of pectins was carried out using UV and IR spectroscopy; simple carbohydrates - using HPLC. Results. It was shown that in the hybrid genotypes fruit tissues the fructose content varied from 36% to 70% of the total sugars. In the tissues of M. baccata fruits the dominant soluble carbohydrates were sorbitol and sucrose. As a result of hybridization, the sorbitol content in fruits decreased significantly (minimum content was found in M. domestica fruits). In most genotypes, the protopectin content was higher than content of water-soluble pectin fractions. The highest total pectin content was found in M. baccata fruits. The esterification of both pectin fractions in the tissues of all genotypes was high—above 50%. The cell size of the hybrids fruits was small compared to M. domestica sell size, varied from 17 to 25 μm. For all the types, cell size did not correlate with fruit size. Conclusion. It is possible that combination of high pectin content, esterification degree and smaller cell size is one of the reasons for the resistance of the studied genotypes to pathogens. EDN: FPDTJC

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.

Aim – study of the fatty acid composition of the aerial parts of L. deminutus. Material and methods. The objects of the study were samples of the aerial parts of L. deminutus harvested on the territory of the Irkutsk region during the mass flowering period (July 2021). The analysis of the fatty acid composition of raw materials of L. deminutus was carried out by Gas chromatography/Mass spectrometry (GC/MS) on the Agilent Technologies 5973/6890N MSD/DS device in 3 repetitions. The relative content of each fatty acid was determined as a percentage by weight of the total amount of fatty acids in the plant raw material (internal normalization method). The absolute content of fatty acids was calculated by the internal standard method. Results. The component composition of the fatty acids of the aerial parts of L. deminutus was studied, 14 compounds were identified, of which 8 saturated fatty acids (5.10±0.12 mg/g) and 6 unsaturated fatty acids (13.41±0.25 mg/g). Palmitic acid (3.41±0.07 mg/g) and stearic acid (0.88±0.02 mg/g) prevail among saturated fatty acids. The dominant compounds among unsaturated fatty acids are linoleic (7.78±0.14 mg/g), α-linolenic (2.21±0.04 mg/g) and oleic (2.19±0.04 mg/g) acids. Conclusion. The qualitative composition of fatty acids in the aerial parts of L. deminutus has been studied for the first time, their quantitative content has been established. L. deminutus is promising for use in medical practice and can be recommended as an additional source of linoleic and α-linolenic acids essential for humans.

The study set out to investigate the effect of different concentrations of copper ions on the composition of phytosterols of the vacuolar membrane (tonoplast) of beetroot (Beta vulgaris L.). To characterise the stress caused by the action of copper ions, a conductometric study of the permeability of cell membranes and the level of lipid peroxidation was carried out. The results demonstrate an increase in these indicators in beetroot tissues. Among tonoplast phytosterols, β-sitosterol, stigmasterol, campesterol, and cholesterol were studied. In cell membranes, these phytosterols perform a structural function, contributing to lipid microdomain formation, influencing plant growth and development, and participating in plant responses to stress. The study of the effect of copper ions on tonoplast phytosterols showed most of them to be occupied by the free form. In the presence of 100 μM copper, a significant increase in campesterol content was detected. The ratio of stigmasterol/β-sitosterol and 24-methyl-/ ethylsterol, which may influence the stress response of plants, is an important indicator of plant membrane health. The observed increases in the ratios of stigmasterol/β-sitosterol and 24-methyl-/ethylsterols can be explained in terms of mechanisms for regulating the functioning of the tonoplast under stress caused by copper ions. Thus, the obtained results may indicate the participation of cell membranes, including tonoplast, in the mechanisms of adaptation of beetroot tissue cells to stress caused by copper ions.

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.

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.

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.

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.