Short-term pigment changes in Norway spruce needles

The photosynthetic pigment contents and the chlorophyll fluorescence induction in Norway spruce [ Picea abies (L.) Karst.] needles were monitored at 3 h intervals over a 10 day period. This covered 6 days of high insolation, one day of low insolation, followed by three more days of high insolation. During the first six days only small changes in mean pigment contents were observed but we interpret them as suggesting a daily rhythm in total chlorophyll content with two maxima and minima. The day of low insolation was paralleled by larger pigment changes, mostly an increase in chlorophyll b along with a decrease in carotenoid content. With the resumption of high insolation, pigments gradually return to their previous levels. During the entire period chlorophyll a fluorescence induction remained relatively constant. These short-term responses may reflect features of thylakoid organization in relation to pigment content and suggest possible long-term adaptive mechanisms in non deciduous conifers.     

Photoinactivation of catalase in needles of Norway spruce

Catalase IEC 1.11.1.6) activity in Norway spruce ( Picea abies [L.] Karst.) needles was examined under different environmental conditions. When shade-adapted spruce trees were exposed to full sunlight or to high light intensities in growth chambers, the catalase activity decreased. Under continuous light the activity was reduced in comparison to the control grown in light/dark cycles. The reduction of the activity was not temperature dependent. Under field conditions the activity was higher in hranches oriented north than in those oriented south. A diurnal rhythm with a maximum in the night was delected. The reduction in catalase activity also occurred in young white needles of Picea ahies vur. argenteospica . which are free of chlorophyll. It is concluded that in Norway spruce needles there is a ligh:-dependent photoinactivation of catalase. which is not temperature-dependent.     

Endophyte communities vary in the needles of Norway spruce clones

Endophytic fungi show no symptoms of their presence but can influence the performance and vitality of host trees. The potential use of endophytes to indicate vitality has been previously realized, but a standard protocol has yet to be developed due to an incomplete understanding of the factors that regulate endophyte communities. Using a culture-free molecular approach, we examined the extent to which host genotype influences the abundance, species richness, and community composition of endophytic fungi in Norway spruce needles. Briefly, total DNA was extracted from the surface-sterilized needles of 30 clones grown in a nursery field and the copy number of the fungal internal transcribed spacer (ITS) region of ribosomal DNA was estimated by quantitative PCR. Fungal species richness and community composition were determined by denaturing gradient gel electrophoresis and DNA sequencing. We found that community structure and ITS copy number varied among spruce clones, whereas species richness did not. Host traits interacting with endophyte communities included needle surface area and the location of cuttings in the experimental area. Although Lophodermium piceae is considered the dominant needle endophyte of Norway spruce, we detected this species in only 33 % of samples. The most frequently observed fungus (66 %) was the potentially pathogenic Phoma herbarum. Interestingly, ITS copy number of endophytic fungi correlated negatively with the richness of ectomycorrhizal fungi and thus potential interactions between fungal communities and their influence on the host tree are discussed. Our results suggest that in addition to environmental factors, endophyte communities of spruce needles are determined by host tree identity and needle surface area.     

Trichloroacetic acid of different origin in Norway spruce needles and chloroplasts

Trichloroacetic acid (TCA), a secondary atmospheric pollutant, is also formed in forest soil and thus ranked among natural organohalogens. The observed biooxidation of atmospheric tetrachloroethene (PER) to TCA in chloroplasts has led to the investigation of the mode of action of TCA in spruce needles, since TCA is also accumulated in the needles after its rapid uptake from soil by roots. Being phytotoxic, TCA considerably influences conifers by affecting their photosynthetic apparatus. We examined the transport of TCA from soil into chloroplasts in order to compare the effects of TCA on conifers from both sources, i.e. endogenously produced within chloroplasts or taken up by roots. The influence of TCA formed in chloroplasts was found to be much more adverse than that of “soil” TCA.     

Incorporation of kaempferol 3-O-glucoside into the cell walls of Norway spruce needles

¹⁴C-Labelled CO₂ fed to young Norway spruce (Picea abies [L.] Karst.) twigs was rapidly incorporated into kaempferol 3-O-glucoside (astragalin) of the needles. The patterns of the time course of total (per needle weight) and specific radioactivity (per amount of compound) of soluble and insoluble (cell wall-bound) astragalin indicate its transport from a soluble pool within the protoplast to an extraprotoplastic cell wall-bound pool within the needle. This conclusion is supported by measurements of the distribution of radioactivity between the aglycone (kaempferol) and the sugar part (glucose) of the molecule after various chase periods as well as by control experiments to determine the localization of [¹⁴C]astragalin in the cell wall preparations.This work was supported by the Deutsche Forschungsgemeinschaft (Schwerpunktprogramm Physiologie der Bäume) and by the Fonds der Chemischen Industrie. We express our special thanks to J. Willenbrink and T. Schatten (Botanisches Institut, Köln, FRG) for advice and help in the ¹⁴CO₂-application experiments. We also thank H. Grisebach (Biologisches Institut II, Freiburg, FRG) for drawing our attention to the work of G. Brandner.     

Pigment composition in Norway spruce needles suffering from different types of nutrient deficiency

 Concentrations of pigments in needles of yellowish Norway spruce [Picea abies (L.) Karst] trees suffering from either N, Mg or K deficiency in field sites in southeast Norway are reported. The yellowish trees had a considerably lower (roughly 50%) pigment concentration, as well as a lower chlorophyll/carotenoid ratio, compared to green trees within the same sites. Yellowing was interpreted as a general bleaching of colour, as well as a slight turn from the green (chlorophylls) towards yellow (lutein). Concentrations of pigments were highly intercorrelated. N deficiency was especially associated with low α-carotene concentrations. This was interpreted as α-carotene being the most sensitive pigment to stress. However, this pigment might be specifically sensitive to N deficiency. Carbohydrate concentrations were slightly higher in yellowish trees. Received: 5 June 1997 / Accepted: 29 August 1997     

Encapsulation of micropropagated buds of six woody species

Regrowth after encapsulation in a sodium alginate matrix of micropropagated buds from six different in vitro proliferated woody species was evaluated. Actinidia deliciosa Liang & Ferguson (kiwifruit), Betula pendula Roth (birch), Crataegus oxyacantha L. (hawthorn), Malus spp. (apple), Rubus spp. (blackberry) and Rubus idaeus L. (raspberry) propagated in vitro were used as bud sources. Encapsulation with sodium alginate and subsequent regrowth on nutrient rich medium was compared to encapsulation with nutrient-enriched alginate capsules followed by regrowth on nutrientless medium. Apical and sub-apical buds of Malus (rootstock M. 27 and cultivar Starkspur Red) were also compared for encapsulation and regrowth ability. All species showed a regrowth after encapsulation, but only if cultured on enriched media. M.27 apical and sub-apical buds showed different regrowth ability after encapsulation with sodium alginate. Applicability of encapsulation of single micropropagated tree buds is discussed.     

Estimating the uptake of traffic-derived NO2 from 15N abundance in Norway spruce needles

The ¹⁵N ratio of nitrogen oxides (NO_x) emitted from vehicles, measured in the air adjacent to a highway in the Swiss Middle Land, was very high [δ¹⁵N(NO₂) = +5.7‰]. This high ¹⁵N abundance was used to estimate long-term NO₂ dry deposition into a forest ecosystem by measuring δ¹⁵N in the needles and the soil of potted and autochthonous spruce trees [Picea abies (L.) Karst] exposed to NO₂ in a transect orthogonal to the highway. δ¹⁵N in the current-year needles of potted trees was 2.0‰ higher than that of the control after 4 months of exposure close to the highway, suggesting a 25% contribution to the N-nutrition of these needles. Needle fall into the pots was prevented by grids placed above the soil, while the continuous decomposition of needle litter below the autochthonous trees over previous years has increased δ¹⁵N values in the soil, resulting in parallel gradients of δ¹⁵N in soil and needles with distance from the highway. Estimates of NO₂ uptake into needles obtained from the δ¹⁵N data were significantly correlated with the inputs calculated with a shoot gas exchange model based on a parameterisation widely used in deposition modelling. Therefore, we provide an indication of estimated N inputs to forest ecosystems via dry deposition of NO₂ at the receptor level under field conditions. Received: 7 November 1997 / Accepted: 16 September 1998     

Cell structural changes in the needles of Norway spruce exposed to long-term ozone and drought

Effects of ozone and/or drought on Norway spruce needles werestudied using light microscopy and electron microscopy. Saplingswere exposed to ozone in open-top chambers during 1992–1995and also to drought in the late summers of 1993–1995.Samples from current and previous year needles were collectedfive times during 1995. Ozone increased the numbers of peroxisomesand mitochondria, which suggests that defence mechanisms againstoxidative stress were active. The results from peroxisomes suggestthat the oxidative stress was more pronounced in the upper sideof the needles, and those from mitochondria that defence wasmore active in the younger needle generation. Possibly due tothe good nitrogen status and the active defence, no ozone-specificchloroplast alterations were seen. At the end of the season,older needles from ozone treatments had smaller central vacuolescompared with other needles. Cytoplasmic vacuoles around thenucleus were increased by ozone in the beginning of the experiment,and did not increase towards the end of the season as in thecontrols. These results from vacuoles may indicate that ozoneaffected the osmotic properties of the cells. Decreased numberand underdevelopment of sclerenchyma cells and proliferationof tonoplast were related to nutrient imbalance, which was enhancedby drought. Larger vascular cylinders and more effective starchaccumulation before and after the drought periods compensatedfor the reduced water status. Numbers of peroxisomes and mitochondriawere increased in the drought-exposed needles before the onsetof drought treatments of the study year, i.e. these changeswere memory effects. Interactions between ozone and droughtwere few.     

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

Summary 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 g/m³) decreased shikimic acid and quinic acid, whereas pH, malic acid and citric acid increased. Ozone (100 g/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.     

Nutrient status in needles of Norway spruce and Scots pine following harvesting of logging residues

Nutrient concentrations in current and 1-year old needles from two Picea abies (L.) Karst and two Pinus sylvestris L. stands in Sweden were determined 8–10, 16–18 and 22–24 years after clear-felling and experimental manipulation of harvesting intensity. On all sites, three levels of harvest intensity had been applied in a randomized block design (n=4); (i) conventional stem-only harvesting, where all logging residues (i.e. tops, branches and needles) were evenly distributed on the ground, (ii) harvesting all above-ground tree parts except needles and (iii) above-ground whole-tree harvesting (no residues left on site). At stand age 8–10 years, nitrogen concentrations in the current year needles in plots where all residues or needles only were retained were higher than in whole-tree harvested plots, whereas concentrations of K, Ca and Mg were lower. The latter response was interpreted as a dilution effect. P:N, K:N, Ca:N, Mg:N, Mn:N and Zn:N were in general higher after whole-tree harvesting treatments than after the treatments where all residues or only needles had been left on site. At stand age 16–18 years, no significant differences in nitrogen concentrations were observed between treatments, but the levels of Ca, Mg and Mn in both current and 1-year-old needles were lower after whole-tree harvesting than after the treatments where logging residues remained on site. By contrast, potassium levels in the foliage were highest in treatments where only the needles were left on site, whereas the lowest levels were observed for treatments where all residues was left. At stand age 22–24 years, the treatment effects had diminished, except for the effects on Ca and K on the southern Norway spruce stand. It is concluded that the nutrient release from logging residues enhances nutrient uptake in trees of the succeeding forest generation, but this effect does not occur simultaneously for all elements. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of drought and waterlogging on ultrastructure of Scots pine and Norway spruce needles

Effects of water stress on needle ultrastructure of 2-year-old Scots pine (Pinus sylvestris L.) and 5-year-old Norway spruce [Picea abies (L.) Karst.] seedlings were studied in greenhouse experiments. Drought stress was induced by leaving seedlings without watering, and waterlogging stress was produced by submerging the seedling containers in water. Needle samples for ultrastructural analyses were collected several times during the experiments, and samples for nutrient analyses at the end of the experiments. In drought stress, plasmolysis of mesophyll and transfusion parenchyma tissues, aggregation of chloroplast stroma and its separation from thylakoids and decreased size and abundance of starch grains in needles of both species were observed. The concentration of lipid bodies around the chloroplasts were detected in pine needles. Calcium and water concentrations in spruce needles were lower by the end of the experiments compared to controls. In waterlogging treatment, swelling of phloem cells in pine needles and large starch grains, slight swelling of thylakoids and increased translucency of plastoglobuli in chloroplasts of both species studied were observed. The phosphorus concentration in pine needles was higher while phosphorus, calcium and magnesium concentrations in spruce needles were lower in the waterlogging treatments compared to controls. Typical symptoms induced by drought stress, e. g. aggregation of chloroplast stroma and its separation from thylakoids, were detected, but, in waterlogging stress, ultrastructural symptoms appeared to be related to the developing nutrient imbalance of needles.     

Dehydration tolerance of leaf tissues of six woody angiosperm species

Electrolyte leakage from leaf discs (measured as an index of dehydration tolerance) increased as water potentials of excised leaves declined for field-grown saplings of six woody species. Until late in the growing season (mid-August), leaves of Cornus florida L. exhibited greater leakage than those of other species; however, in August and September leakage in this species was much reduced, indicating apparent hardening in response to mid-season drought. Leaves of Quercus alba L., Q. rubra L. and Q. velutina Lam. generally exhibited less electrolyte leakage than did those of Acer saccharum Marsh, and Juglans nigra L. over the season. Moreover, leaves of Quercus species showed a reduction in electrolyte leakage late in the season similar to (but less accentuated than) that of C. florida . Saplings of A. saccharum and J. nigra showed little and no drought-hardening response, respectively. The responses shown by the studied species suggest that dehydration tolerance plays a role in plant distribution and that environmentally induced shifts in this tolerance are a significant phenomenon in natural plant communities.     

Variability of Norway spruce (Picea abies L.) needles; performance of spruce sawflies (Gilpinia hercyniae Htg.)

Summary Larvae of the spruce sawfly Gilpinia hercyniae were reared on whole branches of Norway spruce, Picea abies. Top and low branches were selected from flowering and nonflowring stands. Sawfly performance from the larval L₂-stage until the fertile egg stage of the next generation was recorded. Growth and development were best on top branches from the flowering stand, poorest on branches from windblown, partly derooted and heavily flowering trees. Analysis of some 30 biochemicals in needles and faeces was performed. New needles had the highest concentrations of some nutrients (total nitrogen, amino acids), however, G. hercyniae larvae only fed on old needles, a 100% mortality being recorded on newly flushed needles, probably because these needles also contained the highest concentrations of the secondary compound, quinic acid. Old needles showed high variability in concentrations of nutrients and secondary compounds. Regression analysis demonstrated that the total amount of carbohydrates (glucose, fructose and sucrose) was significantly correlated with the larval linear growth rate, the maximal larval weight, the cocoon weight and the number of eggs per female. In these performance variables 72–88% of the variation could be explained by five biochemicals. Survival rates of larvae or pupae and the instantaneous growth rate could not be explained by the biochemical variables. Only weak correlations were found between nitrogen or amino acids and performance variables. Assimilation of the various biochemicals was calculated and showed high rates (90–97%) in hexoses and lower rates (38–65%) in total nitrogen and amino acids.     

Efficiency of the photosynthetic apparatus in developing needles of Norway spruce (Picea abies L. Karst.)

The photosynthetic performance of developing spruce (Picea abies L. Karst.) needles was investigated. As revealed by previous reports, the biosynthesis of chlorophylls and carotenoids was not following the characteristic chloroplast ultrastructure building up during needle elongation process. The aim of our study was to investigate photosynthetic capability (evaluated by oxygen evolution and chlorophyll a fluorescence kinetics measurements), the dynamics of chloroplast pigments biosynthesis and the expression of major photosynthetic proteins as well as to find out possible correlation between components of issue. Low amounts of chlorophylls and carotenoids, LHC II and Rubisco LSU were detected in the embryonic shoot of vegetative buds. Although PS II was functional, oxygen production was not sufficient to compensate for respiration in the same developmental stage. The light compensation point of respiration was successively lowered during the needle elongation. Nevertheless the significant increase in photosynthetic pigments as well as the high level of expression of LHC II and Rubisco LSU proteins was observed in the later stages of needle development. Our results suggest that, besides light, some other environmental factors could be critical for producing fully functional chloroplasts in rapidly growing young needles.