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One of the mechanisms of plant adaptation to combined stress under conditions of altitudinal zonation is changing the lipid fatty acid (FA) composition. The main changes in the FA composition occurred in the outer cell layers of the pericarp, but not in the parenchyma. Adaptation was found to be species-specific. In Cydonia oblonga Mill. and Malus domestica Borkh., the ratio of polyunsaturated 18:2 and 18:3 lipid FAs changed with increasing height, while a constitutive level of the unsaturation index (UI) and low contents of very-long-chain fatty acids (VLCFAs) were maintained. Mespilus germanica L. was characterized by a higher level of VLCFAs due to the high content of 20:0. The sum of VLCFAs in medlar increased by up to 16 % with changing altitude, which was accompanied by the changes in the ultrastructure of chloroplasts and a noticeable decrease in the UI. We attribute the differences in the adaptive strategies in C. oblonga, M. domestica and M. germanica to specific structural features of the pericarp peel. Despite different adaptation mechanisms, the studied species can grow equally successfully at the altitudes from 300 to 1200 m., (© 2019 Wiley-VHCA AG, Zurich, Switzerland.)

The composition of fatty acids of total lipids of the outer and parenchymal parts of the pericarp in Cydonia oblonga Mill. and Mespilus germanica L. (Maloideae, Rosaceae), growing in the Northern Caucasian mountains at altitudes of 300, 500, 700, and 1200 m above sea level in various natural zones from experimental sites, was studied for the first time. It is established that the altitude of plant growth is largely correlated with the changes in the FA composition of the outer, but not the parenchymal, part of the pericarp. The nature of this variability suggests that the adaptation of plants to the conditions of significant temperature differences in the mountains is associated with the regulation of cell membrane fluidity, based on the interaction of opposite processes of synthesis of polyunsaturated and very-long-chain fatty acids.

Asymmetric, optically active sn-1,2-diacyl-3-acetyl-glycerols (AcDAG) have been known to scientists for several decades. However, to date, the problem of their structure has not been definitely resolved, which has led to a vast diversity of terms used for their designation in the literature. Using two-dimensional nuclear magnetic resonance, we have investigated AcDAG from the mature seeds of Euonymus maximowiczianus, from which we have been able to both identify a correlation of the methyl group in acetic acid residue with protons at the carbon atom at sn-3 position in the glycerol residue of the AcDAG molecule and, for the first time, demonstrate that this correlation is observed exclusively with one carbon atom at the α-position, but not with two as would have been expected in case of a racemic mixture. Moreover, results of our analysis of AcDAG isolated from the seeds of E. maximowiczianus directly confirm that diacylglycerol-3-acetyl-transferase is responsible for their biosynthesis, which reveals a strict specificity not only to acetyl-CoA as one of the substrates but also to the sn-3-position of the glycerol residue in sn-1,2-diacylglycerol during their biosynthesis., (© 2018 AOCS.)

The positional-species composition (PSC) of 3-acetyl-1,2-diacyl-sn-glycerols (AcDAGs) from the seeds of mature fruits of 14 species of the genus Euonymus L. was established. The residues of six major fatty acids (FAs), palmitic (P), stearic (St), hexadecenoic (H), octadecenoic (O), linoleic (L), and linolenic (Ln), were present in the AcDAGs. Here, we demonstrated that the profile of PSC of AcDAGs could serve as chemotaxonomic factor to divide euonymus species studied here into groups which completely correlate with the present day systematic of the genus. In particular, the Euonymus section greatly exceeded other sections of the Euonymus subgenus as well as the Kalonymus one in the total levels of AcDAGs positional species having one and two O residues and was characterized by significantly lesser concentrations of species with one and two L residues. Moreover, in seed, AcDAGs of almost all Euonymus species EFL values were slightly higher than EFO ones, but all EFL and EFO values were higher than 1.0, and therefore, it can be concluded that both FAs mainly esterified sn-2-position of the glycerol moiety and saturated FAs residues were always virtually absent in the sn-2 position of Euonymus seed AcDAGs, as it is also the case in nearly all TAGs molecules of plant origin., (© 2016 Verlag Helvetica Chimica Acta AG, Zürich.)

The expression of cold-induced genes, which are controlled by the cold sensor histidine kinase Hik33, and the formation of ω(3) polyunsaturated fatty acids are controlled by light in the cyanobacterium Synechocystis sp. PCC 6803. Cold-induced Hik33-dependent gene expression is initiated by red light (∼700nm), but not by blue or green light. Red light also turns on the ω(3) fatty acid desaturation. Different combinations of other wavelengths in red spectral region (635 and 726nm) had no effect on the red-light-activated cold-induced transcription or fatty acid desaturation. Therefore, the involvement of phytochrome-like photoreceptor(s), similar to phytochromes of higher plants, in this regulation was not confirmed. The absence of light-dependence of gene expression in the mutant cells deficient in Hik33 suggests the involvement of this histidine kinase in direct or mediated with red light regulation of cold responses in Synechocystis., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A comparative study of the tolerance of two species of medicinal plants of the genus Nigella (N. damascene L. and N. sativa L.) to salt stress was performed. It is shown that growing of plants in the presence of 70 or 110 mM NaCl suppressed the growth and accumulation of dry weight of leaves and roots in both species studied and that this suppression was more pronounced at the higher NaCl concentration. It is established that the salt stress leads to the accumulation of proline in leaves and to a change in the fatty acids composition of lipids in the vegetative parts of plants. It is noted that N. sativa has a higher salt tolerance (70-100 mM NaCl) than N. damascena. It is found that the removal of NaCI from the culture medium and subsequent cultivation of plants exposed to salt stress in a salt-free medium led to a gradual recovery of both Nigella species studied. N. sativa plants showed a high ability for recovery (regeneration) after a strong salt stress.

The dynamics of the fatty-acid (FA) composition of neutral acylglycerols (NAGs) composed of 1,2,3-triacyl-sn-glycerols (TAGs) and 3-acetyl-1,2-diacyl-sn-glycerols (acDAGs) was determined in the fruit seeds and arils of three Euonymus L. species at three stages of their maturity. The NAG composition comprised 29 FAs, linoleic, oleic, palmitic, and α-linolenic acids being predominant. Noticeable amounts of other FAs, such as lauric, myristic, hexadec-9-enoic, stearic, (Z)-vaccenic, and arachidic acid, etc., could also be present. In the course of maturation, the qualitative composition of major FAs remained nearly unchanged, while the unsaturation index of FAs in seeds and in TAGs, as well as, but to a lesser extent, in arils and in acDAGs, respectively, always decreased. This decline was brought about by a sharp fall of the α-linolenate level, a decrease of the linoleate content, and a corresponding rise in the oleate content. It is suggested that, in both seeds and arils, both classes of NAGs were formed at the expense of the same FA pool; the quantitative composition of this pool was characteristic of a given fruit part and strongly changed during maturation. The accumulation of TAGs in E. europaeus fruits was accompanied by a conversion of hexadec-9-enoic acid into (Z)-vaccenic acid via the C2 -elongation reaction., (Copyright © 2014 Verlag Helvetica Chimica Acta AG, Zürich.)

Small amounts of a mixture of fatty acid short-chain-alkyl esters (FASCAEs) were obtained from the fruits of twelve plant species of Celastraceae family, and in five of them the FASCAEs were present not only in the arils but also in the seeds. These mixtures contained 32 individual FASCAE species, which formed four separate fractions, viz. FA methyl, ethyl, isopropyl, and butyl esters (FAMEs, FAEEs, FAIPEs, and FABEs, resp.). The FASCAE acyl components included the residues of 16 individual C₁₄-C₂₄ saturated, mono-, di-, and trienoic FAs. Linoleic, oleic, and palmitic acids, and, in some cases, also α-linolenic acid predominated in FAMEs and FAEEs, while myristic acid was predominant in FAIPEs. It can be suggested that, in the fruit arils of some plant species, FAMEs and FAEEs were formed at the expense of a same FA pool characteristic of a given species and were strongly different from FAIPEs and FABEs esters regarding the mechanism of their biosynthesis. However, as a whole, the qualitative and quantitative composition of various FASCAE fractions, as well as their FA composition, varied considerably depending on various factors. Therefore, separate FASCAE fractions seem to be synthesized from different FA pools other than those used for triacylglycerol formation., (Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.)

Cold stress causes unsaturation of the membrane lipids. This leads to adjustment of the membrane fluidity, which is necessary for cold acclimation of cells. Here we demonstrate that the cold-induced accumulation of PUFAs in the cyanobacterium Synechocystis is light-dependent. The desA(-)/desD(-) mutant, that lacks the genes for Δ12 and Δ6 desaturases, is still able to adjust the fluidity of its membranes in spite of its inability to synthesize PUFAs and modulate the fatty acid composition of the membrane lipids under cold stress. The expression of cold-induced genes, which are controlled by the cold sensor histidine kinase Hik33, depends on the fluidity of cell membranes and it is regulated by light, though it does not require the activity of the photosynthetic apparatus. The expression of cold-induced genes, which are not controlled by Hik33, does not depend on the membrane fluidity or light. Thus, membrane fluidity determines the temperature dependence of the expression of cold-induced genes that are under control of the Hik33, which might be the sensor of changes in the membrane fluidity. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial., (Copyright © 2011 Elsevier B.V. All rights reserved.)

We report the expression profile of acyl-lipid Delta12-desaturase (desA) gene from Synechocystis sp. PCC6803 and its effect on cell membrane lipid composition and cold tolerance in prokaryotic (Escherichia coli) and eukaryotic (Solanum tuberosum) cells. For this purpose, a hybrid of desA and reporter gene encoding thermostable lichenase (licBM3) was constructed and used to transform these cells. The expression of this hybrid gene was measured using qualitative (Petri dish test, electrophoregram and zymogram) and quantitative methods (spectrometry and gas liquid chromatography assays). The maximum level of linoleic acid in the bacterial cells containing hybrid gene was 1.9% of total fatty acids. Cold stress tolerance assays using plant damage index and growth parameters showed that cold tolerance was enhanced in primary transgenic lines because of increased unsaturated fatty acid concentration in their lipids. The greatest content of 18:2 and 18:3 fatty acids in primary transgenic plants was observed for lines 2 (73%) and 3 (41%). Finally, our results showed that desaturase could enhance tolerance to cold stress in potato, and desaturase and lichenase retain their functionality in the structure of the hybrid protein where the enzymatic activity of target gene product was higher than in the case of reporter lichenase gene absence in the construction.

Expression of the desC gene coding for acyl-lipid delta(9) desaturase of thermophilic cyanobacterium Synechocystis sp. PCC6803 was studied in Escherichia coli cells. In a hybrid gene constructed (desC-licBM3), a sequence of the native acyl-lipid delta(9) desaturase was fused in frame with the reporter gene coding for thermostable lichenase. Lichenase contained in the hybrid protein simplified selection and analysis of the expression of membrane desaturase in the heterologous host. Comparisons of the expression for the native and hybrid genes in bacterial cells showed that lichenase remained active and thermostable in the hybrid protein, while desaturase retains the capability of introducing a double bound in the corresponding position of fatty acids.

Fatty acid composition and structure in total lipids from the green above-ground parts of four alpine plants, Oxygraphis glacialis, Primula macrophylla, Rhodiola pamiroalaica, and Swertia marginata, were established by GC and GC-MS. A total of 55 fatty acids was detected, and 48 of them were identified. Ubiquitous palmitate, linoleate, and linolenate predominated in the lipids accounting for about 72-90% of the total fatty acids. At the same time, the latter contained numerous species, which were unusual for higher plants and included saturated odd-numbered n-acids (six C15-C25 species, 0.26-1.40%), saturated even-numbered very-long-chain n-acids (six C20-C30 species, 1.00-2.49%), iso-acids (nine C15-C26 species, 0.64-1.53%), anteiso-acids (four C15-C20 species, 0.08-1.57%), certain uncommon mono- and dienoic acids, as well as 16:3omega3, 18:3omega6, and 18:4omega3 acids that are absent from the most higher plants. Nine fatty acids were found here for the first time in higher plants and two may be new to science. The evidence on the unusual fatty acids is discussed with respect to their distribution in living organisms, pathways of biosynthesis, and chemotaxonomic role.

The desC gene for the acyl-lipid Delta9-desaturase from the thermophilic cyanobacterium Synechococcus vulcanus was introduced into Nicotiana tabacum under control of the 35S promoter. Expression of the desaturase was confirmed by Western blotting. Lipid analysis revealed that lipid content and the extent of fatty acid unsaturation significantly increased in leaves of transgenic plants. Chilling tolerance of those plants also increased, as estimated by the electrolyte leakage from the tissues damaged by cold treatments. Seeds of plants that expressed the desC gene imbibed at low temperatures demonstrated higher chilling tolerance than those of the control plants. The results demonstrate that the cyanobacterial thermophilic acyl-lipid desaturase was efficiently expressed in tobacco at ambient temperatures, and its expression resulted in the enhanced chilling tolerance of the transgenic plants.

Changes in the quantitative composition of triacylglycerols (TAGs) in maturing sea buckthorn (Hippophaë rhamnoides L.) seeds were determined by lipase hydrolysis. As a whole, the rate of synthesis of separate TAG classes increased in proportion to both their unsaturation and relative content (weight percent) in total TAGs. Up to the 80th day of maturation, the formation of triunsaturated TAGs was predominant. Subsequently, at the terminal stage of seed ripening, the absolute content (in nanomoles per seed) of a major group of these TAGs containing linolenic and linoleic acyls decreased by approximately 7%, and the increase in the total TAG content was mainly due to the synthesis of TAG molecules including stearic and palmitic acyls in the rac-1,3 positions, as well as those containing oleate in the sn-2 position. At each maturation stage, the composition of the TAGs formed was controlled both by the composition of fatty acids available for TAG synthesis and by the rate of incorporation of a particular fatty acid into the sn-2 position of the TAGs.

The chromatophores of Rhodospirillum rubrum were found to synthesize in the light not only ATP and pyrophosphate but also high molecular weight polyphosphates. Biosynthesis of all studied compounds was inhibited by antimycin A, an inhibitor of the electron-transport photosynthetic chain. Synthesis of high molecular weight polyphosphates is stimulated, while that of pyrophosphate is inhibited, in the conditions providing intensive synthesis of ATP (in the presence of ADP and in the absence of oligomycin). The results obtained suggest that biosynthesis of high molecular weight polyphosphates is related to photosynthetic phosphorylation, via ATP but not pyrophosphate.

Experimental conditions for preparing the thin-layer chromatographic plates with a permanent adsorbent layer (PAL) have been established; the particles of this layer are firmly bound to each other and to the glass support by means of fused glass powder. To prepare the PAL plates, a mixture of Woelm silica gel and glass powder (1:3, w/w) of particle size 7+/-1 mum was suspended in toluene and spread on the plates, yielding PALs of thickens 150-250 mum. The plates were heated in an electric furnace at 675 degrees for 20 min. In the separation of neutral lipids, a PAL thus prepared is equal in efficiency and selectivity to silica gel layers prepared in the usual manner.