Seasonal changes in the fatty acid composition of Pinus sylvestris needle lipids

The fatty acid (FA) composition of common pine (Pinus sylvestris L.) needle lipids was studied. It was shown that FA composition of needle lipids changed during the entire growth period (from March to October) under the influence of environmental factors (temperature, solar radiation) affecting the biosynthesis of chloroplast membrane lipids in pine needles. Among needle lipid FAs, unsaturated polymethylene-interrupted FAs (Δ5-UPIFA) were identified: pinolenic, skiadonic, coniferonic, and other); in March and April, their content attained 16.1 and 16.9% of total FAs; it decreased in June to 6.0% and increased again in September to 20.4%.     

Effect of alternating magnetic field on the composition and level of lipids in radish seedlings

The effects of alternating magnetic field (AMF) with the frequency of 50 Hz on the dynamics of unfolding of cotyledon leaves, the composition and level of polar and neutral lipids and their component fatty acids (FA) were studied in 5-day-old radish seedlings (Raphanus sativus L. var. radicula D.L., cv. Rozovo-krasnyi s belym konchikom) grown in the light and in the dark. AMF weakened the inhibitory effect of light on unfolding of cotyledon leaves. In the light, the total content of lipids, as well as the level of polar and neutral lipids, in the seedlings in AMF was greater than in control material. In polar lipids, the total amount of glyco-and phospholipids increased; in neutral lipids, the level of triacylglycerols rose. The ratio between phospholipids and sterols (PhL/S) increased. In the dark, the total content of lipids and the level of neutral lipids in the seedlings in AMF were lower than in control material, and the ratio PhL/S decreased. In control material, there were no differences in the relative total content of unsaturated FA in the light and in the dark, whereas the level of linolenic acid was higher in the light than in the dark. AMF induced a decrease in the content of linolenic acid in the light and a rise in the dark; the level of erucic acid in the light decreased. The ratio between unsaturated and saturated FA decreased both in the light and in the dark. It was concluded that AMF with the frequency of 50 Hz was an adjusting agent considerably changing the content of lipids in the radish seedlings in the light and in the dark.     

Fatty acid composition of membrane lipids and energy metabolism in mitochondria of pea seedlings under water deficit

The impacts of water deficit and melamine salt of bis(oximethyl)phosphonic acid (melaphen) on the fatty acid (FA) composition of membrane lipids and energy metabolism in mitochondria of 5-day-old pea (Pisum sativum L., cv. Flora-2) seedlings were studied. Insufficient watering resulted in the accumulation of saturated and a decrease in the content of unsaturated FAs with 18 and 20 carbon atoms. Seed treatment with 3 × 10^?10 M melaphen prevented these changes in the FA composition in the mitochondrial membrane lipids. Changes in the FA compositions of membrane lipids were correlated with changes in energy metabolism in mitochondria: the efficiency of oxidative phosphorylation and the rate of NAD-dependent substrate oxidation in the presence of ADP and FCCP (carbonyl cyanide-p-trifluoromethoxyphenylhydrazone) were reduced. A close correlation was observed between changes in the highest rates of NAD-dependent substrate oxidation and the relative content of FAs with 18 (r = 0.76489) and 20 (r = 0.9637) carbon atoms. The regulatory role of C₁₈ and C₂₀ unsaturated FAs in the mitochondrial energy metabolism of pea seedlings is discussed.     

Ribulose bisphosphate carboxylase, protein and nitrogen in Scots pine seedlings cultivated at different nutrient levels

Seedlings of Scots pine (Pinus sylvestris L.) of a northern provenance were cultivated in nutrient solution for 10 weeks in a climate chamber. The nutrient solution (renewed by solution exchange) contained 2.5, 10 or 50 mg N I^?1. All other essential elements were added in optimal proportion to the nitrogen. Seedlings cultivated at 10 and 50 mg N I^?1 were similar with respect to all characteristics studied. Seedlings cultivated at 2.5 mg N I^?1 showed a lower growth rate, especially for the shoot, and an altered morphology, with high root:shoot ratios and long, slender roots. The nitrogen concentrations in shoot and needles as well as in whole seedlings were not significantly affected by the nitrogen supply, while the nitrogen concentrations in the roots were somewhat lower at 2.5 mg N I^?1. Ribulose bisphosphate carboxylase (EC 4.1.1.39) activity and the concentrations of carboxylase, total and soluble protein and of chlorophyll in the needles were consistently much lower for seedlings cultivated at 2.5 mg N I^?1, than for seedlings grown at higher nutrient levels. A close correlation was observed between activity and concentration of the carboxylase (r=0.95). Carboxylase activity and protein were more sensitive to a low nutrient supply than was chlorophyll. The data show how activity and concentration of ribulose bisphosphate carboxylase and the concentrations of soluble and total protein and of chlorophyll in needles of pine seedlings can be negatively affected by the nutrient supply, also when the nitrogen concentrations in the needles are close to those observed at optimal nutrient supply. It is suggested that pine seedlings store assimilated non-protein nitrogen in the needles when protein synthesis is under restraint. The nitrogen concentration in needles and seedlings could not be used as a measure of the physiological state of the seedlings.     

Fatty acid composition of lipids in the calluses of two pine species <Emphasis Type="Italic">Pinus sibirica</Emphasis> and <Emphasis Type="Italic">Pinus sylvestris</Emphasis>

The fatty acid (FA) composition of callus lipids in two pine species, Pinus sibirica Du Tour and P. sylvestris L. was studied. Callus lipids were characterized by a high content of unsaturated FAs: 81.7% in P. sibirica and 63.2% in P. sylvestris. Among them, oleic and linoleic acids predominated (22.9 and 34.0% of total FAs in P. sibirica and 17.6 and 27.8% in P. sylvestris, respectively). Callus lipids also contained Δ5-UPIFA (unsaturated polymethyle-interrupted FAs), where pinoleic and sciadonic acids predominated. A comparison of FAs in the lipids of P. sylvestris calluses derived from needle and needle photosynthesizing tissues of this pine species showed that callus lipids were characterized by a greater diversity of Δ5-UPIFA but a lower degree of FA unsaturation and he higher level of Δ5-UPIFA.     

Effects of frost hardening on the composition of galactolipids and phospholipids occurring during isolation of chloroplast thylakoids from needles of scots pine

Frost hardening of seedlings of Scots pine (Pinus sylvestris) at a non-freezing temperature of 4°C resulted in a 2-fold increase of the acyl lipids of the needles. This was because of increases in phospholipids and triglycerides. The galactolipid content of the needles was almost the same in unhardened and frost-hardened seedlings. In unhardened seedlings the mol ratio of monogalactosyl diacylglycerol (MGDG) to digalactosyl diacylglycerol (DGDG) was 1.7 ± 0.3 and 0.9 ± 0.2 in needles and isolated thylakoids, respectively. Corresponding ratios for frost-hardened seedlings were 1.5 ± 0.2 and 0.3 ± 0.03. The lower ratios found in isolated thylakoids, particularly in thylakoids from frost-hardened seedlings, are suggested to depend on the enzyme galactolipid: galactolipid galactosyltransferase being active during the isolation procedure. This is deduced from the result that the content of MGDG decreased and that of DGDG and 1.2 diglycerides increased. Needles of Scots pine also contain phospholipidase D. This enzyme was active during thylakoid preparation, particularly after frost hardening, as judged from the large amount of phosphatidic acid found the in thylakoid fraction isolated from frost-hardening needles. The fatty acid composition of the acyl lipids showed no major changes due to hardening at non-freezing temperature.     

Changes in fatty acid composition of lipids in chloroplast membranes of tobacco plants during cold hardening

Changes in fatty acid composition of chloroplast membrane lipids were investigated using tobacco (Nicotiana tabacum L., cv. Samsun) plants subjected to cold hardening for 6 days at 8°C. Under optimal growing temperature (22°C), the lipids of thylakoid membranes were characterized by elevated content of 16:3n-3 and 18:3n-3 fatty acids (FA). Compared to the lipids of chloroplast envelope membranes, the thylakoid lipids were less rich in the content of saturated, mono- and diunsaturated FA. The relative content of unsaturated FA in chloroplast membranes increased substantially during cold hardening, which was mainly due to the accumulation of 18:3n-3 FA. It is concluded that the observed changes in FA composition of chloroplast lipids during cold hardening adjust the fluidity of these membranes to the level sufficient for functioning of tobacco photosynthetic apparatus, which is a prerequisite for accumulation of assimilates and allows the hardened tobacco plants to survive under conditions of hypothermia.     

Fatty acid composition of lipids from the vacuolar membranes of the roots of root vegetables

The fatty acid (FA) composition of vacuolar membrane lipids from the storage tissues of parsnip (Pastinaca sativa L.), parsley (Petroselinum crispum L.), and carrot (Daucus carota L.) was studied by gasliquid chromatography, and possible pathways of the biosynthesis of these acids are considered. A high level of unsaturated FAs (up to 78% of the total FA amount) was characteristic of these membrane lipids with the predominance of linoleic acid, which content in vacuolar lipids of parsnip, parsley, and carrot was 53.5, 55.1, and 54.4%, respectively. A high content of hexadienoic acid (C16:2ω6) was characteristic of the vacuolar lipids of parsnip and parsley (8.0 and 4.6%. respectively); the content of α-linolenic acid in the vacuolar lipids of these plants was 4.4–7.3%. Palmitic acid predominated among the saturated FAs (18.0–20.4%).     

Changes in the fatty acid composition of symbiotic dinoflagellates from the hermatypic coral <Emphasis Type="Italic">Echinopora lamellosa</Emphasis> during adaptation to the irradiance level

The composition of fatty acids (FAs) of symbiotic dinoflagellates isolated from the hermatypic coral Echinoporal lamellosa adapted to the irradiance of 95, 30, 8, and 2% PAR was studied. Polar lipids and triacylglycerols (TAG) differed between them in FA composition. Polar lipids were enriched in unsaturated FAs, whereas TAG, in saturated FAs. Light exerted a substantial influence on the FA composition in both polar lipids and TAG. The elevation of irradiance resulted in the accumulation of 16:0 acid in both lipid groups and 16:1(n-7) acid in TAG. It seems likely that de novo synthesis of 16:0 acid occurred actively in the cells of symbiotic dinoflagellates in high light. Since these processes are energy-consuming ones, they utilize excessive energy. When light intensity declined, 18:4(n-3) and 20:5(n-3) acids accumulated in polar lipids, which was accompanied by the increase in the content of chlorophyll a in the cells of zooxanthellae, whereas the levels of 22:6(n-3) and 20:4(n-6) acids reduced. Although the relative content of particular FAs varied substantially in dependence of irradiance, the balance between the sum of saturated and unsaturated FAs changed insignificantly. We concluded that the role of photoadaptation could not be limited only to changes in the degree of lipid unsaturation and membrane fluidity. It is supposed that light-induced changes in the FA composition reflect the interrelation between photosynthesis and FA biosynthesis.     

Fatty acids of plant vacuolar membrane lipids

Fatty acid (FA) composition of vacuolar membrane lipids from storage tissues of umbelliferous plants, viz., parsnip (Pastinaca sativa L.), parsley (Petroselinium crispum L.), and carrot (Daucus carota L.) is studied by gas-liquid chromatography and the FA biosynthetic pathways are considered. Vacuolar membrane lipids are characterized by high (78% of the total FA pool) content of unsaturated FA among which linoleic acid is predominant. Its content in vacuolar lipids of parsnip, parsley and carrot is 53.5, 55.1, and 54.9%, respectively. Parsnip and parsley vacuolar lipids contain large amounts of hexadecadienoic C16:2ω6 acid (8.0 and 4.6%, respectively). The content of α-linolenic acid in vacuolar lipids of tested plants varies from 4.8 to 7.3%. Palmitic acid (18.0–20.7%) predominates among saturated FA. High content of linoleic and hexadecadienoic acid in parsnip and parsley vacuolar lipids is suggestive of a crucial role of the microsomal ω6 fatty-acid desaturase fad2 gene in resistance and acclimation of plants to low temperatures.     

Nitrogen metabolism of Douglas fir and Scots pine as affected by optimal nutrition and water supply under conditions of relatively high atmospheric nitrogen deposition

Nitrogen metabolism of the needles of 40-year-old Douglas fir and Scots pine trees, growing in two forest stands on cation-poor and acidic sandy soil with a relatively high atmospheric nitrogen deposition was studied. The composition of the free amino acid (FAA) pool, the concentrations of total nitrogen and soluble protein and the activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) were determined in the needles. An excessive nitrogen supply by a high atmospheric nitrogen deposition in both forest stands was indicated by the high concentrations of total nitrogen and the amino acids arginine, glutamic acid, glutamine and aspartic acid in control trees. In addition the effect of optimal nutrition and water supply (fertigation) on the needle nitrogen metabolism was evaluated. The total concentration of the FAA pool in needles of both tree species was lower in the fertigated than in the non-fertigated (control) trees, except for 1-year-old needles of Scots pine, in which the concentration after fertigation did not differ from the control. The lower total FAA concentration in the fertigated trees could be attributed to arginine, the concentration of which was on average 60% lower than in the control. Neither the concentration of soluble protein nor the activity of GS were influenced by fertigation. The activity of GDH in fertigated trees only differed significantly from the control in October. Scots pine needles had higher concentrations of protein (50%) and higher activities of GS (44%) and GDH (25%) than Douglas fir needles. Possible explanations for the lower vitality of Douglas fir compared to Scots pine are given.     

Antioxidant responses and water status in Brassica seedlings subjected to boron stress

The effect of boron (B) on growth, water status and oxidative damage was investigated in the leaves and roots of 7-day-old seedlings of Brassica juncea var. Varuna. For this seedlings of Brassica were grown in solution culture with variable boron supply (0.033, 0.33, 3.3 and 33 mg B L^?1) under controlled conditions in green house. Photosynthetic pigments were found to be decreased more under excess (3.3 and 33 mg B L^–1) than deficient boron supply (0.033 mg B L^–1) when compared to control (0.33 mg B L^–1). Accumulation of hydrogen peroxide and thiobarbituric acid reactive substances content in both leaves and roots under deficient and excess boron supply suggested oxidative damage due to excessive production of reactive oxygen species. Increased activity of antioxidative enzymes: superoxide dismutase, catalase and peroxidase along with polyphenol oxidase was observed in leaves and roots under boron deficiency and excess than in control. Increased proline concentration, decreased total water content and water saturation deficit also indicated the water deficit condition in leaves and roots of boron-stressed Brassica seedlings.     

Fatty acids of sponges from the Sea of Okhotsk

The fatty acid (FA) composition of Demospongiae species from the Sea of Okhotsk was studied. Fifteen sponge species were investigated for the first time, and the previously studied species Desmacella rosea and Myxilla incrustans were reexamined for their FA composition. Gas chromatography-mass spectrometry revealed 150 different fatty acids, of which 15 have not been identified in sponge lipids previously. The relative content of saturated FAs varied from 7.6 in Melonachora kobjakovae to 29.6% in Amphilectus digitata, with an average of 14.6% of total FAs. The relative content of monoenic FAs ranged from 12.8 in T. dirhaphis to 27.0% in Polymastia sp., with an average of 20.6% of total FAs. Non-methylen-interrupted, primarily unsaturated Δ5,9-FAs contributed a significantly to the amount of polyunsaturated fatty acids of sponges; this being a distinguishing feature of the FA composition of the investigated group of organisms.     

Fate of lead in the soil and its effects onPinus halepensis

Summary Chemical analysis of samples of needles of Aleppo pine (Pinus halepensis), humus and mineral soil collected in the vicinity of the Pb-smelter in Lavrion, Attica, showed that an area of about 2 km around the smelter is heavily polluted primarily with Pb and also with Zn, S and F^–. Most of the Pb was found accumulated in the humus and the top layer of the mineral soil.About 50% of the Pb found in the samples of Aleppo pine needles could be removed by washing them in a dilute detergent solution. One and 15% of the total Pb from Pb-polluted soil and humus samples, respectively, was extracted with normal ammonium acetate solution. No Pb or a very small amount was extracted with distilled H₂O from humus and soil samples treated with concentrations of Pb as high as 3000 ppm and incubated in the laboratory for 30 days.Humus samples treated with up to 1500 ppm Pb or Pb-polluted humus samples collected from points leeward of the smelter had no adverse effects on the germination of Aleppo pine seeds. When the germination experiment was conducted on Pb-polluted humus samples from points windward of the smelter, where a temporary pine needle death had been observed, the percentage seed germination, for two years, was found reduced and negatively correlated to the distance of the humus sampling point from the Pb-smelter.In nursery experiments Pb concentrations of up to 2000 ppm, added to a calcareous soil, had no adverse effect on height increase of Aleppo pine seedlings. Very little Pb was transported from the roots to the needles after seven months growth of the seedlings on either Pb-amended soil or on Pb-polluted soil from Lavrion. Concentrations of Pb in the roots of the seedlings, however, were found high in both cases and almost proportional to concentrations of Pb in the soil.     

Variation in needle terpenoids among Pinus sylvestris L. (Pinaceae) provenances from Turkey

Variation of terpenes and resin acids in needles of young Scots pine (Pinus sylvestris L.) seedlings from nine different provenances in Turkey was investigated. The provenances represent 1200-km West to East and 400-km South to North transects. Seven monoterpenes and two sesquiterpenes were reported in the needles of pines studied. Generally, the kinds of terpenes were similar but the relative amount of some compounds differed among the origins. The major components of the monoterpene fraction in Turkish sources were α-pinene (84.8%), β-pinene (4.1%) and limonene (3.0%), corresponding to 91.9% of the crude needle extract. In a PCA-analysis, 3-carene, myrcene and terpinolene in seedlings from Turkish provenances were quite low and thus, they were clearly different from a Northern European Scots pine provenance from Finland. In the resin acid fraction, abietic acid (62.4%) and dehydroabietic acid (16.1%) were the most abundant constituents in the needles of the Scots pine from Turkish provenances.     

The Complementarity of Extractable and Ester-Bound Lipids in a Soil Profile Under Pine

Extractable and solvent insoluble, ester-bound lipids were analysed in an acid, sandy soil profile under Corsican pine. The n-alkanes and alkanoic acids from the soil profile showed rather poor correlations with those from the pine needles and roots, while the n-alkanol composition in the mineral horizons strongly indicated the presence of lipids derived from a previous grass vegetation. Although the ester-bound lipids (ω-hydroxyalkanoic acids and α,ω-alkanedioic acids (>C₂₄)) suggested that plant sources other than pines were present in the mineral soil horizons their composition was less contaminated and a clear distinction between needle and root input could be discerned. The divergent clustering of soil horizons and plant materials by individual and combined compound classes emphasized the usefulness of both extractable lipids and cutin/suberin in unravelling (past) vegetation and tissue history and contributions to soil organic matter.     

Imbalanced plant stoichiometry at contrasting geologic-derived phosphorus sites in subtropics: the role of microelements and plant functional group

Aims

In western North America ectomycorrhizal fungi are critical to establishment of conifers in low nitrogen soils. Fire can affect both ectomycorrhizal fungi and soil properties, and inoculation with ectomycorrhizal fungi is recommended when planting on burns for restoration. The aim of this study was to examine how Suillus species used in inoculation affect whitebark pine (Pinus albicaulis L.) seedlings planted in fire-impacted soil.

Methods

In a greenhouse experiment, Suillus-colonized and uncolonized whitebark pine seedlings were planted in unsterilized and sterilized (control) soil from a recent burn. After 6 months, foliar nitrogen and carbon content, concentration, and stable isotope values were assessed, along with growth parameters.

Results

When seedlings were colonized, biomass was 61% greater, foliar nitrogen content 25% higher, foliar nitrogen concentration 30–63% lower; needles had lower δ¹⁵N and higher δ¹³C. Differences were more pronounced in sterilized soil where colonization was higher. Foliar N content was negatively correlated with δ¹⁵N values.

Conclusions

Colonization by host-specific fungi produced larger seedlings with higher foliar nitrogen content in both burn soils. The hypothesis that ectomycorrhizal fungi on roots fractionate nitrogen isotopes leading to lower δ¹⁵N in needles is supported. This helps explain restoration outcomes, and bridges the gap between field and in vitro investigations.

     

Influence of elevated ozone and limited nitrogen availability on conifer seedlings in an open-air fumigation system: effects on growth, nutrient content, mycorrhiza, needle ultrastructure, starch and secondary compounds

Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies Karst.) seedlings were exposed to realistically elevated O₃ levels in open‐air experiments over three growing seasons. The total O₃ exposure doses were 1.2 × (1991), 1.5 × (1992) and 1.7 × (1993) ambient levels. During the 1992 and 1993 growing seasons pine and spruce seedlings received two different levels of nitrogen supply. Effects on growth, mycorrhiza formation, needle ultrastructure, primary and secondary compounds were studied. Ozone exposure had only slight effects on biomass production, growth height and nutrient content of studied conifers. Higher nitrogen availability improved growth of the seedlings and resulted in higher concentration of nitrogen in needles. In Scots pine O₃ exposure did not have effects on quantity of total mycorrhizas and short roots, while higher nitrogen availability decreased quantity of mycorrhizas and short roots. In both tree species O₃ exposure induced O₃‐related ultrastructural symptoms, e.g. granulation and dark staining of the chloroplast stroma in the needle mesophyll cells, at both nitrogen availability levels. Ozone exposure and nitrogen availability did not have significant effects on starch concentrations in either tree species. Concentrations of some individual terpenes were higher in O₃‐exposed needles, while concentrations of individual and total resin acids, total phenolics and catechins were not affected by O₃ exposure. Nitrogen availability did not have substantial effects on concentrations of monoterpenes. By contrast, concentrations of some individual and total resin acids were lower in pine needles and higher in spruce needles with higher nitrogen availability, while phenolic concentration in spruce needles decreased at higher nitrogen availability. The results suggest that realistically elevated levels of O₃ in the field can have some negative effects on the mesophyll ultrastructure of conifer needles, but carbon allocation to root and shoot growth and secondary metabolites are not affected substantially.     

In vivo incorporation of acetate into the acyl moieties of polar lipids from etiolated leek seedlings

Seven-day-old leek seedlings actively synthesize lipids in vivo from [1-¹⁴C]acetate, both in the light and in the dark. In the dark, phospholipid synthesis is more effective than galactolipid synthesis. Whatever the time of acetate incorporation by the etiolated seedlings, very long chain fatty acids having from 20 to 26 carbon atoms are found in all the polar lipids, including the acyl-CoAs. All of the labelled very long chain fatty acids incorporated into the polar lipids are saturated. On the other hand, the labelled C₁₈-fatty acids are unsaturated in phospholipids and galactolipids and almost no label is found in the saturated or unsaturated C₁₈-fatty acids of the acyl-CoAs.