Acid In Needles Research Articles

Changes in Content of Bioactive Compounds and Antioxidant Activity Induced in Needles of Different Half-Sib Families of Norway Spruce (Picea abies (L.) H. Karst) by Seed Treatment with Cold Plasma.

In order to ensure sufficient food resources for a constantly growing human population, new technologies (e.g., cold plasma technologies) are being developed for increasing the germination and seedling growth without negative effects on the environment. Pinaceae species are considered a natural source of antioxidant compounds and are valued for their pharmaceutical and nutraceutical properties. In this study, the seeds of seven different Norway spruce half-sib families were processed for one or two minutes with cold plasma (CP) using dielectric barrier discharge (DBD) plasma equipment. At the end of the second vegetation season, the total flavonoid content (TFC), DPPH (2,2- diphenyl-1-picryl-hydrazyl-hydrate), and ABTS (2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) antioxidant activity, and the amounts of six organic acids (folic, malic, citric, oxalic, succinic, and ascorbic) were determined in the needles of different half-sib families of Norway spruce seedlings. The results show that the TFC, antioxidant activity, and amounts of organic acids in the seedling needles depended on both the treatment duration and the genetic family. The strongest positive effect on the TFC was determined in the seedlings of the 477, 599, and 541 half-sib families after seed treatment with CP for 1 min (CP1). The TFC in these families increased from 118.06 mg g−1 to 312.6 mg g−1 compared to the control. Moreover, seed treatment with CP1 resulted in the strongest increase in the antioxidant activity of the needles of the 541 half-sib family seedlings; the antioxidant activity, determined by DPPH and ABTS tests, increased by 30 and 23%, respectively, compared to the control. The obtained results indicate that the CP effect on the amount of organic acids in the needles was dependent on the half-sib family. It was determined that treatment with CP1 increased the amount of five organic acids in the needles of the 541 half-sib family seedlings. The presented results show future possibilities for using cold plasma seed treatment in the food and pharmacy industries.

Влияние хронического облучения на фитогормональный статус сосен Чернобыльской зоны отчуждения

The paper presents results of the study of impacts of chronic radiation exposure on the hormonal system of the Scots pine in the Chernobyl exclusion zone. Pine needles taken from three experimental plots with a contrasting level of radioactive contamination: the Polesie State Radioecological Reserve, the Kozeluzh’ye forestry and the Khoiniki forestry in June 2021 were used in the study. Artificial stands of the Scots pine were planted in the experimental plots in 1982, few years before the Chernobyl accident. When radiation impact on pine trees was assessed the content of Cs-137, Sr-90, Am-241, Pu-238 и Pu-239+240 in soil and pine needles was taken into account. The absorbed dose rates in the needles taken from contaminated sites varied in the range of 1.5-24.6 µGy/h, the control dose rate was 0.58-0.6 µGy/h. The content of main classes of phytohormones: indol-3-acetic acid, indolyl-3-butyric acid, zeatin and abscisic acid in needles was estimated with the use of high-performance liquid chromatography. No significant changes in the phytohormonal status of pines from the contaminated plots of the Chernobyl exclusion zone were found. No relationship between statistically significant difference in phytohormones content in the pine needles and irradiation exposure is found. The difference may be caused by great biological variability in natural populations or other nonradiation factors.

Content and Composition of Lipids and Their Fatty Acids in Needles of Pinus sylvestris L. and Picea obovata Ledeb. upon Cold Hardening in the Cryolithozone of Yakutia

The composition of lipids and fatty acids (FAs) and changes in their content in needles of summer- and autumn-vegetating conifer trees growing in the cryolithozone of Yakutia have been studied by thin-layer and gas-liquid chromatography–mass spectrometry. A comparative analysis of the content of total lipids (TL) and phospholipids (PL) has been carried out, and the FA composition of TL in needles of Pinus sylvestris L. and Picea obovata Ledeb. has been determined for summer and autumn periods. In the course of adaptation to low autumn temperatures of the Yakutian cryolithozone, the TL content in needles of P. sylvestris and P. obovata significantly (by 30%) increased compared to the summer season. During this period, the phosphatidylcholine content in needles of both species also increased from 13.8 to 31 mg/g dry wt. For both species, the FA lipid composition of needles included a high content of species-specific unsaturated polymethylene-interrupted fatty acids (Δ5-UPIFA). Increase in the content of TL, PL, total FA, and Δ5-UPIFA observed during a temperature drop significantly exceeds that in plants of these species growing in other parts of Siberia. This fact is probably caused by features of low-temperature adaptation of plants in permafrost ecosystems of Yakutia.

Compound-specific carbon isotope patterns in needles of conifer tree species from the Swiss National Park under recent climate change

Elevated CO2 along with rising temperature and water deficits can lead to changes in tree physiology and leaf biochemistry. These changes can increase heat- and drought-induced tree mortality. We aim to reveal the impacts of climatic drivers on individual compounds at the leaf level among European larch (Larix decidua) and mountain pine (Pinus mugo) trees, which are widely distributed at high elevations. We investigated seasonal carbon isotope composition (δ13C) and concentration patterns of carbohydrates and organic acids in needles of these two different species from a case study in the Swiss National Park (SNP). We found that average and minimum air temperatures were the main climatic drivers of seasonal variation of δ13C in sucrose and glucose as well as in concentrations of carbohydrates and citric acid/citrate in needles of both tree species. The impact of seasonal climatic drivers on larch and mountain pine trees at the needle level is in line with our earlier study in this region for long-term changes at the tree-ring level. We conclude that the species-specific changes in δ13C and concentrations of carbohydrates and organic acids are sensitive indicators of changes in the metabolic pathways occurring as a result of climatic changes.

Compound-Specific Carbon Isotopes and Concentrations of Carbohydrates and Organic Acids as Indicators of Tree Decline in Mountain Pine

We investigated seasonal variations in δ13C values and concentrations of carbohydrates and organic acids in needles of declining and healthy mountain pine (Pinus mugo ssp. uncinata (DC.) Domin) trees from the Swiss National Park (SNP), using compound-specific isotopes analysis (CSIA). Our goal was to study the impact of climatic drivers on the individual compounds and understand the reasons of partial tree declines in relation to healthy mountain pine trees under seasonal weather patterns. We found that temperature is the main climatic driver determining the seasonal carbon dynamics at the needle level. Lower seasonal δ13C variability and lower concentration levels of sucrose in needles suggest less photosynthetic activity and sink carbon demand in declining compared to healthy mountain pine trees. Higher concentration levels of hexose (glucose and fructose) can play a reserve function for surviving mechanisms of mountain pine trees. Seasonal patterns of organic acid (malate and citrate) suggest an increasing investment in maintenance and repair mechanisms. The seasonal course of carbohydrates and organic acids can therefore be considered an indicator for a modified carbon metabolism within the leaves and possibly within the other tree tissues, partially explaining the decline of mountain pine trees.

Pinus sylvestris L. and other conifers as natural sources of ascorbic acid

Context: There is a widespread opinion that needles of conifers are a good source of ascorbic acid and may help to cure and prevent scurvy. Aims: To determine the content of ascorbic acid in needles and shoots of Pinus sylvestris, Picea abies, Juniperus communis and several other conifers. Methods: Ascorbic acid content was analyzed by HPLC: aminocolumn 250 mm x 4.6 mm, 5 µm; mobile phase acetonitrile and 0.05 M KH2PO4 (75:25), flow rate 1.0 mL/min, detection at 266 nm. Results: The fresh needles contained more (10.8 x 10-3%) of ascorbic acid than the fresh shoots (5.4 x 10-3%) of the same P. sylvestris tree. In needles collected during one year with monthly intervals from the same pine tree the content of vitamin C varied from 0.5 x 10-3% to 15.7 x 10-3%. The needles gathered in winter from November to March contained much more of ascorbic acid (5.2-15.7 x 10-3%) than needles collected during warmer season (0.5-2.8 x 10-3%). The fresh needles of compared conifers (n=11) contained ascorbic acid from 0% (Tuja occidentalis) to 15.0 x 10-3% (Tsuga canadensis), needles of J. communis contained ascorbic acid a little more (13.3 x 10-3%) than needles of P. sylvestris, P. abies and Microbiota decussata (9.0-10.8 x 10-3%). Conclusions: The concentration of ascorbic acid in needles and shoots of studied conifers is rather low if compared to other natural sources of vitamin C. Fresh plant material of P. sylvestris, P. abies and J. communis contained more ascorbic acid than frozen material. The concentration of ascorbic acid in needles of these three trees was higher than in shoots.

Biochemical Adaptation of Scots Pine (Pinus sylvestris L.) to Technogenic Pollution

We have investigated changes in the complex of biochemical parameters reflecting the disturbance of the homeostatic state and the activity of the adaptive reactions in Pinus sylvestris L. under the conditions of technogenic pollution. Disorders of the physiological state of trees growing under the effect of the excessive accumulation of pollutant elements result in changes in a number of parameters: a decrease in the ratio of protein and nonprotein nitrogen fractions in the needles by 52%; a decrease in the total phosphorus and its acid-soluble fraction by 40 and 63%, respectively; a decrease in carbon concentration by 31%; and a decrease in the amount of chlorophyll a, chlorophyll b, and carotenoids based on the weight of one needle by 23, 40, and 42%, respectively. The activation of protective reactions of pine is proven by an increase in the amount of ascorbic acid in needles by 48%; in the amount of water-soluble phenolic compounds by 29%; in the ratio of Chl. a/Chl. b by 35%; in the ratio of green pigments to yellow by 40%; and in the level of water- and alcohol-soluble proteins 40 and 30%, respectively. The highest activity of biochemical protection components was recorded in trees growing near the Shelekhovsky industrial center, the emissions of which contain a large amount of fluorides and polycyclic aromatic hydrocarbons (PAHs).

Free amino acid concentrations and nitrogen isotope signatures in Pinus massoniana (Lamb.) needles of different ages for indicating atmospheric nitrogen deposition

Free amino acid concentrations and nitrogen (N) isotopic composition in new current-year (new), mature current-year (middle-aged) and previous-year (old) Masson pine (Pinus massoniana Lamb.) needles were determined to indicate atmospheric N deposition in Guiyang (SW China). In different areas, free amino acids (especially arginine) concentrations in new and middle-aged needles were higher than in old needles, and the variation of free amino acids (especially arginine) concentrations in new and middle-aged needles was also greater than in old needles. This indicate that free amino acids in new and middle-aged needles may be more sensitive to N deposition compared to old needles. Moreover, concentrations of total free amino acids, arginine, histidine, γ-aminobutyric acid and alanine in middle-aged needles exhibited a strong relationship with N deposition (P < 0.05). Needle δ15N values showed a strong gradient from central Guiyang to the rural area, with more positive δ15N (especially in old needles) in the city center (0–5 km) and more negative δ15N (especially in old needles) in rural area (30–35 km). These suggest that N deposition in the urban center may be dominated by 15N-enriched NOx-N from traffic exhausts, while it is dominated by isotopically light atmospheric NHx-N from agriculture in rural area. Soil δ15N decreased slightly with distance from the city center, and the difference in δ15N values between the soil and needles (especially for old needles) increased significantly with the distance gradient, indicating that atmospheric N deposition may be an important N source for needles. This study provides novel evidence that free amino acids in needles and age-dependent needle δ15N values are useful indicators of atmospheric N deposition.

NITROGEN, BORON AND AMINO ACID LEVELS IN THE NEEDLES OF SCOTS PINE SEEDLINGS WITH CONTROLLED NITROGEN AND BORON SUPPLY

The content of nitrogen, boron and free amino acids were studied in needles of Scots pine (Pinus sylvestris L.) seedlings as related to variations in nitrogen and boron availability. Interrelated effects of nitrogen and boron on the amino acid composition in needles were identified. Boron content in needles rose in line with boric acid dosage, and application of nitrogen reduced boron levels in needles. The high nitrogen and the optimal boron doses enlarged the content of total and protein nitrogen and total free amino acids in needles. Nitrogen applications in combination with three different levels of boron availability mainly raised arginine levels, but also promoted the content of ornithine and lysine. The content of OH-lysine, glutamic and aspartic acids, alanine, serine, threonine, proline and methionine in needles increased when boron was deficient, and rose when boron supply was optimal. Optimization of boron nutrition in low nitrogen settings raised total free amino acid content in needles owing to a rise in glutamic and aspartic acids, alanine and OH-lysine, whereas in high nitrogen settings the rise was mainly owing to arginine. Phenylalanine and tyrosine levels in the latter case also rose, but the levels of the rest of amino acids declined. Application of the high dose of boric acid against two nitrogen backgrounds in- duced a reduction or a downward trend in the content of all forms of nitrogen and a major- ity of free amino acids in needles, except for cysteine in a simultaneous low- and proline in a high nitrogen treatment.

The effect of industrial air pollution on membrane lipid composition of Scots pine (Pinus sylvestris L.) needles

This work was undertaken to determine lipids changes in needles of Scots pine (&lt;em&gt;Pinus sylvestris &lt;/em&gt;L.) populations growning on polluted stands near a phosphate fertilizer factory in Luboń, and copper smelter in Głogów and in a control area in Kórnik. Needles from polluted areas had a lower content of total phospholipids than samples from the unpolluted site. Greater changes were detected in membranes of needles collected in October and January. In comparison with the control total phospholipid in needles of populations from polluted areas were 14 to 33% lower. Phosphatidylcholine (PC) phosphatidylethanolamine (PE) and phosphatidylglicerol (PG) were the dominant phospholipids. The analysis of fatty acids in phospholipid fraction showed a decrease of linoleic acid (18:2) and linolenic acid (18:3) contents. The level of polyunsaturated fatty acids in needles of three populations from polluted areas was up to 40% lower as compared with the control. Moreover, phospholipids and their fatty acids showed seasonal fluctuations. The contents of PC, PG and PE increased in autumn and in winter, during the process of cold acclimation. In July, current-year needles did not show significant differences in membrane lipid composition between the polluted areas of Scots pine populations. The results suggest that the lipid changes of needles could be associated with disturbances in phohospholipid metabolism, caused by environmental pollution.

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.

Profiling Secondary Metabolites of Needles of Ozone-Fumigated White Pine (Pinus strobus) Clones by Thermally Assisted Hydrolysis/Methylation GC/MS

Plant secondary metabolites have an important role in defense responses against herbivores and pathogens, and as a chemical barrier to elevated levels of harmful air pollutants. This study involves the rapid chemical profiling of phenolic and diterpene resin acids in needles of two (ozone-tolerant and ozone-sensitive) white pine (Pinus strobus) clones, fumigated with different ozone levels (control, and daily events peaking at 80 and 200 ppb) for 40 days. The phenolic and resin acids were measured using thermally assisted hydrolysis and methylation (THM) gas chromatography/mass spectrometry. Short-term fumigation affected the levels of two phenolic acids, i.e., 3-hydroxybenzoic and 3,4-dihydroxybenzoic acids, in that both showed a substantial decrease in concentration with increased ozone dose. The decrease in concentration of these THM products may be caused by inhibition of the plant's shikimate biochemical pathway caused by ozone exposure. The combined occurrence of these two ozone-sensitive indicators has a role in biomonitoring of ozone levels and its impact on forest productivity. In addition, chromatographic profile differences in the major diterpene resin acid components were observed between ozone-tolerant and ozone-sensitive clones. The resin acids anticopalic, 3-oxoanticopalic, 3beta-hydroxyanticopalic, and 3,4-cycloanticopalic acids were present in the ozone-sensitive pine; however, only anticopalic acid was present in the ozone-tolerant clone. This phenotypic variation in resin acid composition may be useful in distinguishing populations that are differentially adapted to air pollutants.

Reproductive capacity of the grey pine aphid and allocation response of Scots pine seedlings across temperature gradients: a test of hypotheses predicting outcomes of global warming

The effects of the expected increase in growing season temperature on the performance of the aphid Schizolachnus pineti (Fabricius) (Homoptera: Lachnidae) and on the nutritional quality of its host plant (Pinus sylvestris L.) were studied under a daytime temperature range of 20–28 °C, with nighttime temperature that was either fixed at 12 °C or 8 °C below the daytime temperature. Fecundity had a curvilinear response, with an optimum at 24 or 26 °C, which is 4 to 6 °C above the local mean daytime temperatures. Longevity of nymphal stage was negatively and linearly correlated (r2 = 0.967) with daytime temperature. Intrinsic rate of population increase (rm) and relative growth rate were significantly higher at 26 °C than at 20 °C. Fecundity and rm were negatively correlated with total phenolic concentration in needles. Temperature affected concentrations of some individual resin acids in needles and stems, while concentrations of monoterpenes, total phenolics, starch, and total nitrogen in needles were not affected by temperature. Seedlings grown at 24 °C achieved the greatest biomass. Results support the protein competition hypothesis, which predicts no changes in the concentration of plant phenolics with small temperature increases. However, at 26 °C the low starch/nitrogen ratio and low total phenolic concentration may partly explain increased fecundity of aphids.

Effect of provenance on free amino acid and chemical composition of Scots pine needles

Free amino acid (16 amino acids) and chemical composition (N, P, K, Mg, Ca, S, Fe, Mn, Cu, Zn) of Scots pine (Pinus sylvestris L.) needles were compared between six provenances in three different experimental areas. The main free amino acids in the needles were in the sequence of quantity; glutamic acid, glutamine, arginine and γ-aminobutyric acid. There were no significant differences in the concentrations of phenylalanine, γ-aminobutyric acid, methionine, proline and threonine in pine needles between the sites or between the provenances. Significant differences in the foliar concentrations of alanine and leucine were found between the sites and in the foliar concentrations of isoleucine, glutamine, glycine and tyrosine between the provenances. The concentrations of aspartic acid, glutamic acid, arginine and lysine were significantly affected by the sites and the provenances. The foliar nutrients, except copper, had statistically significant differences, both between the sites and between the provenances. Calcium did not differ between the provenances.

Abscisic acid in needles of Pinus cembra in relation to ozone exposure.

Ozone pollution was analyzed in arolla pine (Pinus cembra L.) forests growing over two mountain ranges located in southern France by using specific ozone-sensitive tobacco plants as bio-indicators and a physico-chemical analyzer. Concentrations of abscisic acid (ABA) were determined in needles of healthy and declining trees in a massif with a declining forest and in a massif with a healthier forest. In addition, ABA was quantified in needles of trees exposed to either charcoal-filtered air or unfiltered air supplemented with ozone in open-top chambers located at the Col du Donon. The concentration of ABA in needles of injured trees increased when the trees were exposed to ozone either under field conditions or in open-top chambers; however, the difference in ABA concentration between control and ozone-exposed needles was less in the open-top chambers, where ozone was the sole variable, than in the field. The results are discussed in the context of the effects of ozone on plant water relations and hormone-mediated cell defense.

SO2‐dependent cation competition and compartmentalization in Norway spruce needles

ABSTRACTIon contents in needles from Norway spruce trees [Picea abies (L.) Karst.] growing in Würzburg and in the SO2‐polluted Erzgebirge mountains were analysed to quantify cations which accumulate together with sulphate. In Würzburg there was a positive correlation of potassium (0.680 ± 0.300 Eq Eq−1 SO4−2), magnesium (0.415 ± 0.111 Eq Eq−1 SO4−2) and zinc (0.059 ± 0.006 Eq Eq−1 SO42−). In the Erzgebirge, potassium was also the stoichiometrically most important cation (0–887 ± 0–180 Eq K+ Eq−1 SO42−). All other correlations examined were weak or statistically non‐significant. At both sites the calcium content of spruce needles did not depend on the sulphate content. The lack of a role for Ca2+ in neutralizing sulphate is a consequence of the presence of free oxalic acid in needles. Soluble oxalic acid precipitates Ca2+, which thereby becomes unavailable as a counterion for SO42−. The activity coefficients of Ca2+ and oxalate2−, and the solubility product of Ca‐oxalate, were determined from in vivo data. It is concluded that the chronic accumulation of atmospheric sulphate in spruce needle vacuoles depletes available potassium and thereby strongly interferes with spruce growth and canopy turnover. This leads to impaired spruce vitality, even at sites where acute SO2 disease symptoms are absent.

Contents of free amino acids in needles of Norway Spruce trees in relation to novel forest decline. Studies on trees from a site in the northern Black Forest

The free amino acid content in needles of Norway spruce trees (about 45-year-old) was determined by means of HPLC. The studied trees have been growing at a forestry site in the Black Forest which is characterized by a high impact of ozone and magnesium deficiency. Measurements were carried out on visibly healthy and on damaged trees on several dates during two vegetation periods and during the course of a day. The amino acids occurring at the highest concentrations were glutamate, arginine, aspartate, and glutamine. The typical seasonal changes in the content of free amino acids, with their minimum during summer, were disturbed in the needles of the damaged trees. Particularly in summer and autumn the damaged trees showed increased levels of total amino acids and of most single amino acids. During the course of a day, the needles of the damaged trees showed a reduced amplitude in diurnal variations with the absolute level almost always higher in comparison to that of the undamaged trees. The results suggest that a shift in protein turnover towards enhanced degradation has taken place.

Phenolic acids as biochemical parameters to indicate stress in orchards of Pinus pinaster

The content of free and combined phenolic acids (gallic, protocatechuic, p-hidroxybenzoic, vanillic, siringic and p-cumaric) in seedlings of Pinus pinaster of one year old exposed to different types of stress (excess of humidity, mechanic damage, salinity, drought, SO2 contamination, heat and cold), is analyzed through Liquid Chromatography (HPLC). From the statistic analysis one can deduce that the influence of the exposure to different types of stress is significant in relation to the content of the different phenolic acids in needles. The content of free protocatechuic acid falls after three months of exposure to any treatments of strees but salinity. After one a half year, one can observe an increase in the content of combined gallic acid in ester form for all treatments previously mentioned. The contamination of SO2 induces significant increases of free gallic, vanillic, siringic y p-cumaric acids, and combined siringic and p-cumaric acdis in branches. It can also be observed statistic differences in roots, but less significant.

Quantitative analysis of abscisic acid in needles of Abies alba Mill. by electron capture gas chromatography

The amount of abscisic acid (ABA) in needles of silver fir from a natural location was investigated with regard to position in the crown, damage, seasonal variation, and needle age. Because of problems of quantification of ABA in coniferous needles, which contain numerous secondary plant products, a method for reliable determination of both isomers cis-trans-ABA (c-ABA) and transtrans-ABA (t-ABA) was developed. By means of gas chromatography (GC) using an electron capture detector (BCD) and a programmed temperature vaporizer (PTV) injector complete separation of both compounds was achieved. Two different pairs of fir were investigated — in each case a damaged and a healthy tree. Needles from both trees from the first and the second pair collected in September contained 500–1100 ng c-ABA/g fresh weight (FW), and the concentrations of t-ABA varied from 400 to 700 ng/g FW. Investigations from the second pair show highest amounts of 2900 ng/g Fw c-ABA and 1800 ng/g FW of t-ABA in May and June. For the first pair a higher c-ABA content was found in needles from the top of the crown than in those from the middle and the base. This difference could not be confirmed in the analysis of the second pair. Because of the strong natural deviation no statistically significant difference between the healthy and the damaged tree was found. The first pair of firs examined showed a higher t-ABA concentration than the second one. In this case the highest amount was found in the top of the crown. Methodical mistakes during the clean-up procedure and in quantification by gas chromatography could be excluded. The presence of c- and t-ABA in the purified extract was corroborated by mass spectrometry. With regard to the seasonal variation both isomers of ABA show an unequivocal trend. The maximum concentration is achieved in May to June, whereas the content is minimal in August/September. In any case the level of t-ABA is lower than that of c-ABA. No correlation between the amount of ABA and the needle age could be established.

Effects of ozone on organic acids in needles of Norway spruce and Scots pine

The effect of ozone, needle age, and season on the pH of homogenate and acid contents of Scots pine and Norway spruce needles is presented. In addition enzyme activities of cytochrome C-oxidase (cyt. C-ox), phosphoenolpyruvate-carboxylase (PEPC), shikimic acid-dehydrogenase (SHDH) and malate-dehydrogenase (MDH) were measured in Scots pine needles. In freshly sprouted spruce needles the level of quinic acid is high and the pH of the needle homogenate is low. Shikimic acid starts at low levels, increases with increasing needle age and becomes dominant, whereas the quinic acid content decreases. Malic acid has a marked seasonal trend; no trend was found in citric acid. Ozone (200 μg/m3) decreased shikimic acid and quinic acid, whereas pH, malic acid and citric acid increased. Ozone (100 μg/m3) had a similar effect, except in the current-year spruce needles. In Scots pine needles ozone led to increased enzymatic activities of cyt. C-ox, PEPC and SHDH, and a decrease in the activity of MDH. This effect was more pronounced in summer than in autumn, but the visible damage was greater in autumn. These effects can be found with other stresses and are not specific for ozone.