Total Acyl Lipids Research Articles

Biosynthesis and Transfer of α-Elostearic Acid In Vivo in Momordica charantia L. Developing Seeds and In Vitro in Microsomal Fractions of These Seeds.

The research concerned the efficiency of biosynthesis and transfer to triacylglycerols (TAG) of α-eleostearic acid (αESA). The experiments were carried out on developing seeds of Momordica charantia L. and on microsomal fractions obtained from these seeds. The seeds from in vivo conditions were collected 20, 23, 26 and 33 days after pollination (DAP) and used for lipid extraction and further analyses. Microsomal fractions were prepared from seeds at 26 DAP. The most intensive lipid accumulation occurred between 20 and 26 DAP, but continued up to 33 DAP. The most abundant lipid fraction was TAG; up to 98% of total acyl lipids at 33 DAP. The synthesised in vivo αESA was very efficiently transferred to TAG and constituted about 60% of its total fatty acids in 33 DAP. The content of αESA in polar lipids (containing, among others, phosphatidylcholine-the place of αESA biosynthesis) was very low. The biosynthesis of αESA in vitro (assays with microsomal fractions and [14C]-labelled substrates) in the presence of NADPH was fairly intensive (about 60% of the corresponding intensity in vivo) when linolenic acid was used as a substrate. Contrary to the in vivo condition, most of the synthesised in vitro αESA remained in phosphatidylcholine.

Fatty Acid Composition by Total Acyl Lipid Collision-Induced Dissociation Time-of-Flight (TAL-CID-TOF) Mass Spectrometry.

Totalacyllipid collision-induced dissociation time-of-flight (TAL-CID-TOF) mass spectrometry uses a quadrupole time-of-flight (QTOF) mass spectrometer to rapidly provide a comprehensive fatty acid composition of a biological lipid extract. Samples are infused into a QTOF instrument, operated in negative mode, and the quadrupole is used to transfer all, or a wide mass range of, precursor ions to the collision cell for fragmentation. Time-of-flight-acquired mass spectra provide mass accuracy and resolution sufficient for chemical formula determination of fatty acids in the complex mixture. Considering the limited number of reasonable CHO variants in fatty acids, one can discern acyl anions with the same nominal mass but different chemical formulas. An online application, LipidomeDB Data Calculation Environment, is employed to process the mass spectral output data and match identified fragments to target fragments at a resolution specified by the user. TAL-CID-TOF methodology is a useful discovery or screening tool to identify and compare fatty acid profiles of biological samples.

Downregulation of key genes involved in carbon metabolism in Medicago truncatula results in increased lipid accumulation in vegetative tissue

AbstractAlfalfa (Medicago sativa L.) is the most widely grown perennial forage crop and is a close relative of the model diploid legume Medicago truncatula Gaertn. However, use of alfalfa leads to substantial greenhouse gas emissions and economic losses related to inefficiencies in rumen fermentation. The provision of supplemental lipids has been used as a strategy to mitigate these issues, but it is a costly approach. The ability to enhance lipid content within the vegetative tissues of alfalfa would therefore be very advantageous. As such, our aim was to assess and select gene candidates to increase total shoot lipid content in M. truncatula using a virus‐induced gene silencing (VIGS) approach. We targeted gene homologs of the SUGAR‐DEPENDANT 1 (SDP1), ADP‐GLUCOSE‐PYROPHOSPHORYLASE SMALL SUBUNIT 1 (APS1), TRIGALACTOSYLDIACYLGLYCEROL 5 (TGD5), and PEROXISOMAL ABC TRANSPORTER 1 (PXA1) in M. truncatula for silencing. Reduced target transcript levels were confirmed and changes of shoot lipid content and fatty acid composition were measured. Silencing of SDP1, APS1, and PXA1 each resulted in significant increases in shoot total lipid content. Significantly increased proportions of α‐linolenic acid (18:3Δ9cis,12cis,15cis) were observed, and stearic acid (18:0) levels significantly decreased in the total acyl lipids extracted from vegetative tissues of each of the M. truncatula silenced plants. In contrast, palmitic acid (16:0) levels were significantly decreased in only SDP1‐ and PXA1‐silenced plants. Genes of PXA1 and SDP1 would be ideal targets for mutation as a means of improving the quality of alfalfa to increase feed efficiency and minimize greenhouse gas emissions from livestock production in the future.

Triacylglyceride composition and fatty acyl saturation profile of a psychrophilic and psychrotolerant fungal species grown at different temperatures

Pseudogymnoascus destructans is a psychrophilic fungus that infects cutaneous tissues in cave dwelling bats, and it is the causal agent for white nose syndrome (WNS) in North American (NA) bat populations. Geomyces pannorum is a related psychrotolerant keratinolytic species that is rarely a pathogen of mammals. In this study, we grew P. destructans and G. pannorum in static liquid cultures at favourable and suboptimal temperatures to: 1) determine if triacylglyceride profiles are species-specific, and 2) determine if there are differences in fatty acyl (FA) saturation levels with respect to temperature. Total lipids isolated from both fungal spp. were separated by thin-layer chromatography and determined to be primarily sterols (∼15 %), free fatty acids (FFAs) (∼45 %), and triacylglycerides (TAGs) (∼50 %), with minor amounts of mono-/diacylglycerides and sterol esters. TAG compositions were profiled by matrix-assisted laser desorption–ionization time-of-flight mass spectrometry (MALDI–TOF). Total fatty acid methyl esters (FAMEs) and acyl lipid unsaturation levels were determined by gas chromatography–mass spectrometry (GC–MS). Pseudogymnoascus destructans produced higher proportions of unsaturated 18C fatty acids and TAGs than G. pannorum. Pseudogymnoascus destructans and G. pannorum produced up to a two-fold increase in 18:3 fatty acids at 5 °C than at higher temperatures. TAG proportion for P. destructans at upper and lower temperature growth limits was greater than 50 % of total dried mycelia mass. These results indicate fungal spp. alter acyl lipid unsaturation as a strategy to adapt to cold temperatures. Differences between their glycerolipid profiles also provide evidence for a different metabolic strategy to support psychrophilic growth, which may influence P. destructans' pathogenicity to bats.

Growth, lipid production and metabolic adjustments in the euryhaline eustigmatophyte Nannochloropsis oceanica CCALA 804 in response to osmotic downshift

We investigated the effects of osmotic downshift induced by the transfer of Nannochloropsis oceanica CCALA 804 from artificial seawater medium (27gL(-1) NaCl) to the same medium without NaCl or freshwater modified BG-11 medium (mBG-11) as a function of photosynthetically active radiation (170, 350, or 700μmol photon m(-2)s(-1)). Alterations in growth, total fatty acid (FA) content and FA composition of individual lipid classes, and in relative contents of metabolites relevant to osmotic adjustments were studied. Cells displayed remarkable tolerance to the osmotic downshift apart from some swelling, with no substantial lag or decline in cell division rate. Biomass accumulation and chlorophyll a content were enhanced upon downshifting, especially under the highest irradiance. The highest chlorophyll a and eicosapentaenoic acid (EPA) biomass and culture contents were determined in the cultures grown in mBG-11. Two days after transfer to 0 g L(-1) NaCl, the proportion in total acyl lipids of the major chloroplast galactolipid monogalactosyldiacylglycerol, a major depot of EPA, increased twofold, along with a modest change in the proportion of digalactosyldiacylglycerol (DGDG). EPA percentage decreased in DGDG and increased in the extraplastidial lipid phosphatidylethanolamine. Metabolite profiling by GC-MS analysis revealed a sharp decrease in metabolites potentially involved in osmoregulation, such as mannitol and proline, while proline-cycle intermediates and some free sugars increased. The stress-induced polyamine spermidine decreased ca. one order of magnitude, while its catabolic product-the non-protein amino acid γ-amino butyric acid-increased twofold, as did the stress-related sugars trehalose and talose. Biochemical mechanisms governing osmotic plasticity and implications for optimization of EPA production by N. oceanica CCALA 804 under variable cultivation conditions are discussed.

Galactolipase activity but not the level of high-melting-point phosphatidylglycerol is related to chilling tolerance in differentially sensitive Zea mays inbred lines.

Galactolipase activity, the level of high-melting-point phosphatidylglycerol (HMP-PG) as well as degradation of lipids during chilling and rewarming were studied in seedlings of maize inbred lines with different chilling responses. In aged chloroplasts of chilling-sensitive (CS) lines, galactolipase activity was considerably higher than that determined in aged chloroplasts isolated from chilling-tolerant (CT) ones. Chilling of seedlings at 5 °C for 6 days induced neither loss of chlorophyll content nor visible changes in the leaves, while a slight decline in total acyl lipid content by about 15.5% and 12.5% in CS and CT lines, respectively, was observed. Among total acyl lipids, only monogalactosyldiacylglycerol (MGDG) levels were decreased significantly upon chilling. Following return to the original growth conditions for 4 days, visible chilling injury in seedlings as well as essential differences in the decrease in total acyl lipids by about 53% and 20% in CS and CT lines, respectively, were found. These changes were accompanied by more extensive degradation of MGDG, digalactosyldiacylglycerol and phosphatidylglycerol in CS than in CT lines. As the levels of HMP-PG in fresh leaves were the same in all four lines of maize, it seems that galactolipase activity and not the level of HMP-PG is related to chilling response in maize.

Galactolipase and chilling sensitivity of plants.

Galactolipase is a lipid acyl hydrolase (EC 3.1.1.26) acting predominantly on galactolipids which constitute up to 80% of total acyl lipids in chloroplast membrane. Evidence is presented on the involvement of this enzyme in plant response to chilling via degradation of membrane lipids and the increase of free fatty acids, associated with reduced oxygen evolution in the Hill reaction. The occurrence of two pools of fatty acids has been hypothesized. Analysis of numerous plant species showed higher galactolipase activity in the chilling-sensitive than in the chilling-resistant plants. Differences in the pH-dependence curve and in the response to detergents of galactolipases from these two groups of plants suggest heterogeneity of the enzyme. Referring to the hypothesis concerning the role of high melting-point fatty acids of phosphatidylglicerol molecular species in chilling sensitivity the data are presented against generalization of this hypothesis.

Liquid-phase composition of intact fruit tissue measured by high-resolution proton NMR

High-resolution 1 H (proton) NMR spectra were obtained on intact fruit tissues (grape, banana, and apple). Liquid-phase component line width showed field-dependent broadening due to magnetic susceptibility effects; the effect was larger in more physically heterogeneous tissues (apple>banana>grape). Magic angle spinning (MAS) reduced susceptibility broadening, while water peak suppression increased dynamic range, enabling detection of components at levels at least as low as 0.01% of fresh weight. Water, glucose, fructose, sucrose, organic acids (malic, citric, tartaric), and total fatty acyl lipids were quantified

Lipid composition of the brown algae fucus vesiculosus and Ascophyllum nodosum

The lipid composition of the two brown marine algae, Fucus vesiculosus and Ascophyllum nodosum, was very similar. The major acyl lipids were monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulphoquinovosyidiacylglycerol and trimethyl-β-alaninediacylglycerol. The major phospholipid was phosphatidylethanolamine but this represented less than 10% of the total acyl lipids. Monogalactosyldiacylglycerol was the most unsaturated lipid, with high proportions of eicosapentaenoic and octadecatetraenoic acids and sulphoquinovosyidiacylglycerol was the most saturated glycolipid with high proportions of palmitate and oleate. The phospholipids phosphatidylcholine and phosphatidylethanolamine had very similar fatty acid patterns, with around 60% of their acyl chains being arachidonic acid. In Fucus vesiculosus the galactosyldiacylglycerides had most of the 16C acyl chains esterified at the sn-1 position. α-Linolenic acid and eicosapentaenoic acid were also mostly esterified to the sn-1 position while octadecatetraenoic acid was concentrated at the sn-2 position. Both sulphoquinovosyldiacylglycerol and phosphatidylglycerol showed typically prokaryotic positional distribution of fatty acids with 16C chains concentrated at the sn-2 position. Of these, trans-Δ 3-hexadecenoic acid was exclusively esterified to the sn-2 position of phosphatidylglycerol.

Effects of Physiological and Ontogenetical Ageing on Membrane Lipid Levels in Pea Leaves ( Pisum sativum)

Summary The membrane lipid composition of leaves from pea was investigated during different stages of ageing. Total fatty acids, phospholipids, and free sterols were determined, on the one hand, in leaves of different maturity from plants with nine pairs of leaves, on the other hand, in newly unfolded leaves of plants of different ages. The leaves of different maturity were regarded as representing different stages of physiological ageing. The total fatty acids as well as the phospholipids decreased with increasing age. The level of free sterols was, however, constant. This implied a decrease in the mol ratio of free sterols/phospholipids from 0.16 to 0.33. The fatty acid composition of phosphatidylcholine changed to a lower unsaturation degree. The newly unfolded leaves of plants of different ages represented a variation in ontogenetical age with a constant level of physiological maturity. The total acyl lipids and the phospholipids of the newly unfolded leaves varied in a complex way during ontogenetical ageing and showed a min value at a plant size of seven leaves. The free sterols decreased with age. As a consequence the mol ratio of free sterols/phospholipids fluctuated between 0.1-0.2. Taken together the results indicate that the membrane lipid composition of pea leaves changes and reflects that form of ageing which prevails.

The transmembrane distribution of galactolipids in chloroplast thylakoids is universal in a wide variety of temperate climate plants

The transmembrane distribution of monogalactosyldiacylglycerol and digalactosyldiacylglycerol was determined in chloroplast thylakoids from a range of temperate climate plants. These plants included dicotyledons, monocotyledons, C16:3 and C18:3 plants and herbicide-resistant species. In all the thylakoids examined monogalactosyldiacylglycerol was enriched in the outer leaflet (53-65%) while digalactosyldiacylglycerol was highly enriched in the inner leaflet (78-90%). The non-bilayer forming monogalactosyldiacylglycerol represented 55-81% of the total acyl lipids of the outer monolayer. The relative acyl lipid composition of both leaflets of the thylakoid membrane indicates that the lamellar structure is strongly favored in the inner monolayer, whereas the outer one presents a metastable character which allows the probable coexistence of both lamellar and non-lamellar phases. The consequence of this asymmetry for the stability and function of the thylakoid membrane is discussed.

Effect of light intensity on pigments and main acyl lipids during ?natural? chloroplast development in wheat seedlings

The content and composition of pigments and acyl lipids (monogalactosyl diacylglycerol, digalactosyl diacylglycerol and phosphatidyl glycerol) have been investigated in developing chloroplasts isolated from successive 2-cm sections along the leaves of wheat seedlings grown either under 100, 30 or 3 W·m(-2). In all examined stages of plastid development chlorophyll a/b and chlorophyll/carotenoid ratios were higher with increasing irradiance, whereas chlorophyll content expressed on fresh weight basis gradually decreased.Concentrations of monogalactosyl diacylglycerol, digalactosyl diacylglycerol and phosphatidyl glycerol decreased per chlorophyll unit with increasing plastid maturity. The higher was the light intensity applied during plant growth, the higher were galactolipid and phosphatidyl glycerol contents in developing chloroplasts. During plastid development the percentage of α-linolenic acid markedly increased in total and individual acyl lipids. Under high light conditions, the accumulation of this fatty acid proceeded more rapidly. Significantly higher proportion of α-linolenic acid was found in acyl lipid fraction of chloroplasts differentiating in high light grown plants, than in those from plants exposed to lower light intensities. The differences in the double bond index may indicate higher fluidity of thylakoid membranes in sun-type chloroplasts.Trans-3Δ-hexadecenoic acid, virtually absent in the youngest plastids, was found in much higher concentration (per chlorophyll unit and as mol % of phosphatidyl glycerol fatty acids) in chloroplasts developing at high light conditions.

Transversal localization of monogalactosyldiacylglycerol and digalactosyldiacylglycerol in spinach thylakoid membranes

The lipase from Rhizopus arrhizus has been used to determine the transmembrane distribution of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) in spinach thylakoid membranes. The hydrolysis kinetics, expressed as semilog plots, were carried out at constant bulk pH under a wide range of salt concentration and temperatures. DGDG always showed two pools of constant amplitude, regardless of the conditions used. The behavior of MGDG was more complex. Depending on environmental conditions, two or three pools could be evidenced. We have developed a simple rationale which allows to distinguish between kinetic pools (identified as different populations of lipid molecules being degraded at different hydrolysis rates within the outer monolayer) and topological pools (corresponding to the classical outside/inside distribution). It is suggested that the surface potential and temperature are involved in the control of the packing pressure of thylakoid membrane lipids, as probed by the lipolytic enzyme. We defined a limited set of conditions under which it is possible to obtain reliable estimations of the transversal distribution of galactolipids in thylakoid membranes. For spinach, the outside/inside ratios are 15 85 for DGDG and 65 35 for MGDG. Taking into account the contribution (in mol%) of these lipids to the total acyl lipid composition, it is deduced that total galactolipids are equally distributed within the two monolayers of the thylakoid membrane. The implications of these results for the overall molecular organization of the thylakoid membrane will be discussed.

Changes in lipid composition of oat root membranes as a function of water-deficit stress

The effect of repeated water-deficit stress on the lipid composition of root cells from 5-day-old oat (Avena sativa L. cv. Seger) seedlings was studied. The content of total acyl lipids was found to decrease with increasing degree of water-deficit stress, owing largely to decreases in free fatty acids, triglycerides, phosphatidylethanolamine (PE), wax esters, steryl esters, and acylated steryl glycosides. Major polar lipids both in total root cells and in the plasma membrane enriched fraction, as well as the microsomal membrane fraction, were PE, phosphatidylcholine (PC), digalactosyldiacylglycerol (DGDG), monogalactosyldiacylglycerol (MGDG), and polyglycolipid. Decreases in the degree of unsaturation of the fatty acids as a funtion of increased water-deficit stress were observed for the MGDG and polyglycolipid components of total root cells and for the MGDG, DGDG, and polyglycolipid of the plasma membrane fraction. Electron microscopy showed that stressed root tip cells had much smoother plasma membranes than those of control unstressed root cells. These results suggest that root cells of oat seedlings respond to water-deficit stress by reducing the total plasma membrane mass and degree of lipid fluidity, which would reduce the water permeability of the plasma membranes and help maintain cell turgidity.

The effect of low oxygen concentration on the acyl-lipid and fatty-acid composition of the C4 plant Amaranthus paniculatus L.

Acyl lipids and their constituent fatty acids were studied in leaves, chloroplasts and bundle-sheath strands of the C4 plant Amaranthus paniculatus L. grown under normal and 4%-oxygen-containing atmospheres. In all fractions the major lipids were found to be monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulphoquinovo-syldiacylglycerol and phosphatidylglycerol. Significant quantities of phosphatidylcholine and phosphatidylethanolamine were restricted to leaves and bundle-sheath strands. All lipids, except phosphatidylglycerol where 3-trans-hexadecenoic acid was also present, contained palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid. On a chlorophyll basis and compared with whole leaves, the amounts of phosphatidylcholine and phosphatidylethanolamine in bundle-sheath strands were considerably reduced. Three weeks after the change from a normal to a 4% atmospheric O2 level, the galactolipid content, particularly in the bundlesheath strands, was enhanced. There were no significant differences in the degrees of saturationunsaturation of total acyl lipid for the plants grown in the low oxygen and normal atmospheres, although under 4% O2 the phosphatidylglycerol contained an increased proportion of 3-trans-hexadecenoic acid at the expense of palmitic acid.

Lipids and lipid metabolism in the brown alga, Fucus serratus

The lipids of the brown alga Fucus serratus were isolated, identified and quantified. The major acyl lipids were the three glycosylglycerides, diacylgalactosylglycerol, diacyldigalactosylglycerol and diacylsulphoquinovosylglycerol. These represent over 70% of the total acyl lipids. The fatty acid compositions of the major lipids were examined and most showed rather distinctive fatty acid contents. For example, diacylgalactosylglycerol was enriched in n-3 polyunsaturated fatty acids while phosphatidylcholine and phosphatidylethanolamine had very high levels of arachidonate. Phosphatidylglycerol contained the unusual trans-Δ3-hexadecenoic acid. The labelling of lipids and fatty acids from [ 14C]acetate was examined and the distribution of label between individual components as a function of the incubation period and in algae collected at different times of the year is reported. Algae collected in the winter incorporated much more radioactivity into non-esterified fatty acids when compared to algae collected in the summer. All algae could label myristate, palmitate, stearate and oleate at high rates. Longer incubation times allowed the labelling of polyunsaturated fatty acids such as linoleic acid.

Influence of winter and summer growth conditions on leaf membrane lipids of Pisum sativum L.

The lipid composition and degree of unsaturation of fatty acids has been measured for membranes isolated from leaves of Pisum sativum grown under either summer or winter conditions. Although the lipid-class composition was not significantly changed for the two growth conditions the degree of unsaturation of the fatty acids was greater for winter than summer plants. The difference in unsaturation was evident with all lipid classes of the non-thylakoid membranes including the galactolipids of the chloroplast envelope. In contrast, both the relative amounts of lipid classes and degree of saturation were not greatly changed for summer and winter thylakoids with the exception that phosphatidylglycerol had a greater linolenic acid (18:3) content for the thylakoids of winter grown leaves. However, a striking difference was found for the total acyl lipid to chlorophyll ratio for thylakoids isolated from summer or winter plants, with the former producing a lower ratio than the latter growth conditions. The above changes in lipid composition of chloroplast membranes are discussed in terms of optimizing their functional activities under the different growth conditions.

Acyl Lipids, Pigments, and Gramine in Developing Leaves of Barley and Its Virescens Mutant

Changes in acyl lipids and pigments during leaf development in a virescens barley mutant (M) and the normal (N) were studied. Apical 3-cm leaf segments were extracted with chloroform-methanol, the extracts were purified on Sephadex G-25 columns, and the polar lipids were separated on two-dimensional-thin layer chromatography silica gel plates. The pigment remaining on the Sephadex column was identified as flavonoids and a zone on the TLC plates which did not correspond to the usual standards was identified as gramine. Quantification of acyl lipids by either polar head group analysis or fatty acid analysis using heptadecanoate as an internal standard gave similar results. The per cent of the total lipid extract quantified for the M between 4 and 8 days ranged from 46 to 65% and that for the N ranged from 60 to 68%. Of these, acyl lipids represented 37 to 48% in the M and 43 to 50% in the N. By 8 days, mono- and digalacto-syldiglyceride (MG and DG) accounted for 45 and 25% of the total acyl lipid of both the M and N. For the period of study here, this represented a 4-fold increase in MG and a 2.5-fold increase in DG in the M but only a 1.8-fold increase for MG and DG in the N. These increases were closely correlated with the increases in chlorophyll. Chlorophyll increased sharply between 4 and 6 days for the N, whereas, in the M, it rose from 7 to 50% relative to the normal by 8 days. The proportions of the various fatty acids were unique for the lipid classes. The only major quantitative change for a fatty acid was for hexadecanoate in phosphatidylglycerol which increased from 5% at 4 days to 25 to 30% by 8 days. Relative to the N, the carotenoid content of the M increased from 14 to 50% between 4 and 8 days. In both the M and N, the increase in beta-carotene and chlorophyll were closely correlated.

Effect of Light on Lipid and Fatty Acid Composition of Cyanobacteria, Anacystis nidulans (Synechococcus)

Pigment alterations could be obtained by exposing Anacystis cultured under low white light (0.6 X 10 3 µW/cm 2 ) to high white light (3 X 10 4 µW/cm 2 ) or high red light (2 X 10 4 µW/cm 2 ). The amounts of total pigments and acyl lipids decreased from red light to high white light grown cells. Within the different cultures a relative constant proportion of lipid soluble pigments and acyl lipids could be observed. Regarding to the influence of culture conditions on the composition and percentage distribution of individual aryl lipids no effect on SQDG could be noted but high light irrespective of light quality leads to a slight -decrease in PG content. Galactolipids and the MGDG/DGDG-ratio proved to be dependent on the chosen illumination. High red light yielded in an increase in MGDG synthesis, while high white light dependent lipid decrease was lesser for DGDG than for all other lipids. In high white light grown cultures a glycolipid, not yet reported to occur in Anacystis nidulans or other cyanobacteria was detected. Concerning the fatty acid composition, this lipid shows the lowest degree of desaturation of all lipids investigated. The sugar moiety of this unknown lipid is still to be researched. Common for all cultures the galactolipids can be divided from SQDG and PG in the percentage distribution of their faty acids. C 16 : 0 , C 16 : 1 and C 18 : 1 as major components in all lipids show little to, no difference in percentage distribution between cyanobacteria grown in low white and high red light. High white light led to a relative higher amount of C 16 : 0 and C 18 : 1 in all acyl lipids, whereas C 18 : 1 correspondingly decreased. As minor fatty acid components in lipids of all cultures C 14 :0 C 14 : 11 C 17 :15 C 18 : 0 and C 20 : 0 were observed.

The distribution of acyl lipids in the germ, aleurone, starch and non‐starch endosperm of four wheat varieties

AbstractThe quantitative distribution of 23 classes of acyl lipids was determined in the germ, aleurone, starch and endosperm non‐starch fractions of Atou (Soft English), Flinor (Hard English), Waldron (US Hard Red Spring) and Edmore (US Amber Durum) wheats. All four wheats had similar proportions (dry basis) of pericarp (6.8–8.6%), germ (2.5–3.0%), starchy endosperm (78.7–84.5%) and starch (59.3–67.5%), and similar quantities of acyl lipids in the whole kernels (2.8–3.2%), germ (25.7–30.5%), starch (0.8–1.2%) and endosperm non‐starch fractions (0.8–1.1%). Flinor, Waldron and Edmore had 7.3–10% aleurone containing 8.7–10.6% lipids, but Atou appeared to have an abnormally low aleurone weight (4.0%) and a correspondingly high lipid content (19.4%). Pericarp acyl lipids were studied only in Atou, where they comprised 1.3% of the dry weight and 3.8% of the total acyl lipids in the whole kernel. Lipids in the germ and aleurone consisted of triglycerides (60.3–79.3%), other nonpolar lipids (5.6–12.0%) and phospholipids (13.6–17.9%). Starch lipids were almost exclusively lysophospholipids (89.4–94.4%). Greater variation was found in the endosperm non‐starch lipids which consisted of triglycerides (13.7–34.1%), other nonpolar lipids (33.2–48.5%), glycolipids (18.6–38.3%) and phospholipids (21.9–35.3%). Edmore had the highest levels of triglycerides and non‐polar lipids, and the lowest levels of glycolipids (as expected in a tetraploid wheat). Atouresembled Edmore in its low levels of steryl esters and glycolipids, but it also had least phospholipids.