Soluble Amino Compounds Research Articles

Significance of Ozone Exposure for Inter‐Annual Differences in Primary Metabolites of Old‐Growth Beech (Fagus sylvatica L.) and Norway Spruce (Picea abies L.) Trees in a Mixed Forest Stand

The influence of long-term free-air ozone fumigation and canopy position on leaf contents of total glutathione, its redox state, non-structural proteins (NSP), soluble amino compounds, and total soluble sugars in old-growth beech (FAGUS SYLVATICA) and spruce (PICEA ABIES) trees were determined over a period of five years. Ozone fumigation had weak effects on the analysed metabolites of both tree species and significant changes in the contents of total glutathione, NSP, and soluble sugars were observed only selectively. Beech leaves were affected by crown position to a higher extent than spruce needles and exhibited lower contents of total glutathione and NSP and total soluble sugars, but enhanced contents of oxidised glutathione and amino compounds in the shade compared to the sun crown. Contents of total soluble sugars generally were decreased in shade compared to sun needles of spruce trees. Interspecific differences between beech and spruce were more distinct in the sun compared to the shade crown. Contents of total glutathione were increased whilst contents of amino compounds and total soluble sugars were lower in spruce needles compared to beech leaves. The metabolites determined showed individual patterns in the course of the five measurement years. Contents of total glutathione and its redox state correlated with air temperature and global radiation, indicating an important role for the antioxidant at low temperatures. Correlations of glutathione with instantaneous ozone concentrations seem to be a secondary effect. Differences in proteins and/or amino compounds in the inter-annual course are assumed to be a consequence of alterations in specific N uptake rates.

Impact of Elevated PCO2 on Mass Flow of Reduced Nitrogen in Trees†

AbstractTo analyze the effects of elevated carbon dioxide concentration (PCO2) on the mass flow of reduced nitrogen (N) in the phloem and xylem of trees, juvenile beech (Fagus sylvatica L.) and spruce (Picea abies (L.) Karst.) were grown in phytotrons and exposed to ambient and elevated PCO2 (plus 687.5 mg/m3 CO2) for three growing seasons. Elevated PCO2 significantly decreased the mass flow of N from the shoot to roots of beech by significantly reducing the concentration of soluble amino compounds in the phloem, even if the area of conductive phloem of cross‐sectional bark tissue was significantly increased, because of less callus deposition in the sieve elements. In spruce, the downward mass flow of reduced N also tended to be decreased, similar to that in beech. Resembling findings in the phloem, N mass flow from roots to shoot in both tree species was significantly diminished owing to significantly reduced concentrations of amino compounds in the xylem and a lower transpiration rate. Therefore, the mass flow of reduced N between shoots and roots of trees was mainly governed by the concentrations of soluble amino compounds in the phloem and xylem in relation to the loading of reduced N in both long‐distance transport pathways.(Managing editor: Ya‐Qin Han)

Effects of elevated pCO 2 and/or pO 3 on C-, N-, and S-metabolites in the leaves of juvenile beech and spruce differ between trees grown in monoculture and mixed culture

Three and four-year-old saplings of beech ( Fagus sylvatica L.) and spruce ( Picea abies (L.) Karst.) grown in monoculture and mixed culture were exposed in phytotrons to (1) ambient air, (2) elevated pO 3, (3) elevated pCO 2, or (4) elevated pCO 2 plus elevated pO 3. After 5 months, the contents of soluble sugars, starch, soluble amino compounds, non-structural proteins (NSP), as well as reduced (GSH) and oxidized (GSSG) glutathione were determined in the leaves of both species in order to assess the effects of the gaseous regimes on primary metabolism. Elevated pO 3 did not affect sugar and starch levels in beech leaves in monoculture, but significantly increased sugar levels in beech leaves grown in mixed culture. In spruce needles, sugar levels tended to be enhanced in both culture types. Individual and combined exposure of elevated pCO 2 led to an increase in non-structural carbohydrate (soluble sugars plus starch) levels in beech and spruce leaves of both culture types. Differences in the responses of non-structural carbohydrate levels to elevated pCO 2 between beech and spruce were apparent from different contributions of sugars and starch to the increase in carbohydrate levels. Exposure to elevated pCO 2 and/or elevated pO 3 did not affect the levels of soluble amino compounds and NSP in beech leaves, but reduced amino compound levels in spruce needles of both culture types. Elevated pO 3 increased GSH levels in the leaves of both tree species in both culture types, while GSSG levels in monoculture were reduced in beech leaves, but significantly enhanced in spruce needles. Elevated pCO 2 reduced GSSG levels in beech and spruce leaves in monoculture, and GSH levels in spruce needles of both culture types. The combination of elevated pCO 2 and pO 3 increased GSSG levels in beech leaves of both culture types and in spruce needles in monoculture, but reduced GSH levels in spruce needles of both culture types. Apparently, under each gaseous regime, the culture type significantly altered primary metabolism of the leaves of beech and spruce.

Nitrogen forms in bark, wood and foliage of nitrogen-fertilized Pinus sylvestris.

Cycling of soluble non-protein N compounds is thought to be indicative of the N-nutritional status of trees. We determined the major N forms in bark, wood and foliage and estimated the dependence of prevalent N forms on N availability in Pinus sylvestris L. trees from northern Sweden. Trees subjected to severe N limitation and trees that had been fertilized with an average 64 kg N ha(-1) year(-1) for 25 years were analyzed. Bark and wood samples were collected by tangentially cryo-sectioning the trunk into 30-microm thick sections, from the bark to the functional xylem. Soluble amino compounds were extracted from the sections for analysis. Sap samples from twigs were obtained by centrifugation, and bark samples from twigs were obtained by tissue extraction. In both needles and bark, arginine dominated the amino-N pool. Because arginine concentrations in needles increased with N fertilization, arginine dominance of the amino-N pool in needles was higher in N-fertilized trees than in control trees. In bark, N fertilization resulted in a large increase in glutamine concentration, so that glutamine accounted for a larger proportion of the amino-N pool in bark in N-fertilized trees than in control trees. Glutamine dominated the amino-N pool in wood of control trees. Nitrogen fertilization resulted in an increased proportion of arginine in the wood amino-N pool. We conclude that the composition of the amino-N pools in bark, wood and foliage is highly sensitive to N supply. The composition of the amino-N pools can contribute to the regulation of tree N-nutritional status, which is mediated by shoot to root signalling by long-distance transport of amino compounds.

Ammonium in plant tissue: Real or artifact?

Tissue analysis of plant material is used to estimate the level of sufficiency or deficiency of any particular nutrient. Published values of ammoniumammonia reported in plant cell extracts would have been toxic to plants, if these values are really present in the cell. We believe that the ammonia determined in plant tissue is actually ammonium produced by the decomposition of soluble amino compounds in the plant tissue during the extraction or analytical procedure. Therefore, pure amino acid solutions and water extracts of wheat (Trticum aestivum L) and melon (Cucumis melo L) leaves were examined by several analytical procedures for nitrate‐nitrogen (N‐NO3) and ammonium‐nitrogen (N‐NH4). The results showed that glycine, alanine, glutamic acid, and methaionine released more than 7% of its nitrogen (N) as ammonium during the auto analyzer procedure. Water extracts of melon leaves from plants grown in ammonium solution exhibited more ammonium than those of plants grown in nitrate alone. Wheat grown in high N‐fertilized plots, released more N‐NH4 in the distillation of their leaf water extracts than plants grown in low N‐fertilized plots. The N‐NH4 content decreased with plant age and with a decrease in total N concentration. It is concluded that ammonium determined in water extracts of plant material is a result amino acid breakdown during the analytical procedure. The values depend on plant age and the composition of its amino acids, analytical method employed, distillation time, pH and temperature during the reaction time.

Taproot nitrogen accumulation and use in overwintering alfalfa ( Medicago sativa L.)

Alfalfa (Medicago sativa L.) taproots accumulate organic reserves that are important for winter survival and subsequent growth in spring. Our objective was to determine if specific nitrogen (N) pools accumulate in taproot tissues prior to winter that may subsequently be used during initiation of herbage growth in spring. Taproots were obtained at approximately monthly intervals during fall and winter, and biweekly in early spring. Taproots were separated at the cambium into bark and wood tissues. Bark tissues consistently contained higher N concentrations than did wood tissues. N concentrations of both tissues gradually increased between early and late fall and declined in early spring when growth was initiated. Both soluble amino-N and buffer-soluble proteins increased during autumn and declined extensively during early spring in both tissues. A nonwinterhardy alfalfa line accumulated less soluble protein in taproot tissue when compared to a hardy genotype. Specific proteins with molecular masses of 32, 19, and 15 kDa were identified as major components of the buffer-soluble protein pool. These proteins rapidly disappeared from taproot tissues in spring as buffer-soluble protein concentrations declined. Protease activity in bark tissues declined gradually during late autumn and winter before increasmg over two-fold in early spring. Protease activity in wood tissues was approximately one-half that of bark tissues and also increased in spring when growth resumed. Our results indicate that high concentrations of soluble amino compounds and specific proteins accumulate in taproots during autumn and early winter. These N pools decline markedly in spring coincident with the onset of herbage growth.

Divergence in Organic Anion and Amino Compound Concentrations in Different Parts of the Leaves of Posidonia oceanica (L.) Delile

Three fractions — white bases, green laminae, and brown apical parts — of leaves of Posidonia oceanica were collected and the distribution of organic anions, amino acids, starch, and sugars was investigated. Organic anions reached their highest levels in the brown parts and amino compounds were accumulated mainly in the green laminae. The concentrations of starch and soluble carbohydrates increased from the apices towards the bases. Tartrate and malonate dominated in the brown apical parts, whereas oxalate was the main organic anion in the photosynthetically active green laminae. Both malate and glycollate were found at high levels in the white bases. In the carbohydrate and amino-compound fractions the main components were sucrose and asparagine, respectively. As far as the main storage form of soluble amino compounds is concerned Posidonia is an asparagine accumulating type, just like many fresh-water macrophyte species.

Effects of Shading or Removing Spikelets in Wheat: Testing Assumptions.

Shading for 10 days reduces the supply of sucrose available for distribution to the grains, and the amounts of sucrose in the endosperm, but has no effect on the delivery of soluble amino compounds to the grain. Soon after returning shaded plants to full illumination, the supply of sucrose to the ear is restored to unshaded levels. In addition, shading affects the amounts of ethanol-insoluble material in the peduncle and the rachis, and the nitrogen content of this material in the peduncle. Trimming ears to four spikelets (10 days after anthesis) results in an increased supply of sucrose and soluble amino compounds available for distribution to the remaining grains. More nitrogen enters the grains of trimmed ears than intact ones, but inflow of sucrose is not increased by trimming the ear, and no more starch is deposited in grains developing in trimmed ears. While the responses to shading observed in this work indicate that the interpretation of the effects of shading on the growth of cereal grains may not be straightforward, the use of shading as a treatment for investigating physiological processes such as grain growth is not disqualified. However, as removing spikelets results in several unpredicted, and inexplicable, responses in the grain itself, the value of such a treatment as a means of investigating mechanisms regulating the accumulation of dry matter in the cereal grain is questionable.

Uptake and Distribution of Nitrogen in Young Apple Trees after Application of Nitrate or Ammonium, with Special Reference to Asparagine and Arginine

AbstractApple rootstocks M.7 were given either nitrate or ammonium at the end of September. Until the following June, total and protein nitrogen and the composition of the soluble nitrogen fraction were followed in the roots, stem‐bark, and new growth. Nitrogen from both sources was readily absorbed in roughly the same amounts. Absorption occurred in the autumn and especially in the following spring. Incorporation of the absorbed nitrogen took place exclusively in the young roots. Arginine and, to a lower degree, asparagine were by far the most abundant of the soluble amino compounds and reached levels far above those in the unfertilized trees. The asparagine/arginine ratio was rather high during the first few weeks after fertilization but then dropped steadily to a low winter level. During May and June there was a gradual decrease to very low levels, especially in the new growth. The data suggest that the absorbed nitrogen is incorporated into asparagine and that arginine is formed from asparagine if the supply of nitrogen exceeds the immediate needs.Throughout the experimental period, ammonium fertilization led to higher values of the asparagine/arginine ratio than did nitrate nutrition. This is explained in terms of an enhanced production of asparagine and a retarded conversion into arginine. It is argued that asparagine is the main translocation compound for nitrogen. The possibility is discussed that, in addition, arginine moves upwards by a process of exchange along the negatively charged walls of the xylem vessels.

Der Einfluß der Kalium‐Ernährung auf den Gehalt und das Spektrum löslicher Aminoverbindungen in Rotklee (Trifolium pratense L.)

Effect of potassium nutrition on the content and the spectrum of soluble amino compounds in Red Clover1. A better K nutrition of Red Clover (Trifolium pratense) resulted in higher contents of soluble amino acids of the upper plant parts. The plants of the treatment with the highest K application showed nearly double as high contents of glutamic acid, aspartic acid, alanine and γ‐aminobutyric acid than the plants of the K0 treatment. The content of asparagine was not as much affected by the K nutrition and the content of glutamine was even lowered.2. Red Clover responded on the K treatment with its content of soluble amino compounds quite different than non leguminous plant species which show decreasing contents of soluble amino acids with an increasing K nutrition. Therefore it is concluded, that the K nutrition of legumes affects the N2‐fixation of Rhizobium leguminosarum.3. The higher contents of soluble amino compounds did not influence the protein content of the upper plant parts. But with the better K supply the yields were increased considerably and therefore also higher yields of proteins were harvested. Very low K supply resulted in a high protein content, due to an inhibition of plant growth.

Phloem Translocation of Storage Nitrogen in Apple

AbstractMobilization of nitrogenous compounds during the spring was studied in ringed isolated shoot sections (bearing one intact bud each) from Golden Delicious apple trees and in intact stem‐ringed apple rootstocks M VII. The changes in total, protein and soluble nitrogen and soluble amino acids and amides were followed in the bark of the shoot sections for 3 weeks during leafing‐out and in the shoot and stem bark of the rootstocks for 6 weeks starting at bud‐break.Ringing prevented nitrogen movement from below the ring both in the shoot sections and in the rootstocks almost completely, thus demonstrating the importance of the phloem as translocation pathway for stored nitrogenous compounds, even over longer distances.Asparagine and arginine were the major soluble amino compounds throughout. The values of the asparagine/arginine quotient in the various tissues suggest that when the distance between points of nitrogen supply and demand is short asparagine is translocated preferentially, but that at increasing distance this preference shifts to arginine.

Der Einfluß einer variierten K‐Ernährung auf die Inkorporierung von markiertem Stickstoff (15N) bei jungen Sonnenblumen (Helianthus annuus L.)

The effect of a varied K nutrition upon the incorporation of labelled nitrogen (15N) in young sun flower plants (Helianthus annuus L.)1. The influence of the potassium nutritional status upon the incorporation of labelled nitrogen (15N) into the soluble amino fraction and into the protein fraction was studied with young sun flower plants (Helianthus annuus L.). The plants were cultivated in a solution culture with 3 different nitrogen and 2 different potassium levels. During the last 24 hours of this cultivation the nitrogen of the nutrient solution was labelled by 15N‐nitrate in the various treatments.2. The growth of the plants was affected considerably by the various nutritional treatments. The yield of the plant matter increased with increasing nitrogen supply. This nitrogen effect was enhanced by the better potassium nutrition.3. The contents of soluble amino compounds in roots and upper plant parts increased with the increasing nitrogen application. This tendency was reduced by the higher potassium supply. The contents of protein nitrogen rose with the nitrogen nutrition. Potassium reduced the content of protein nitrogen in treatments with high growth rates.4. Related on a single plant the incorporation rate of nitrate nitrogen into the organic matter was higher in plants with a good potassium nutritional status than in plants with a low potassium nutritional status. This effect was especially evident in the treatments with the highest nitrogen supply. Here the nitrate incorporation rate was 5–7 times higher with the higher potassium application.5. This favorable effect of potassium upon the assimilation of nitrate nitrogen was also evident, if the incorporation rate was not related to a single plant, but on the unit of weight of plant material (fresh matter). Thus with high nitrogen supply the quantity of labelled nitrogen of the amino fraction was about 2 times higher in the plants with a high potassium nutritional status compared with plants of a low potassium nutritional status. In the protein fraction this potassium effect was still more evident. The influence of potassium upon the nitrate nitrogen assimilation was the better the better the plants were supplied with nitrate.

Effects of nitrogenous components of the medium on the carbohydrate and nucleic acid content of Mycobacterium tuberculosis BCG.

Summary: The effects of varying the concentrations of the nitrogen sources in glycerol + asparagine, glycerol + asparagine + casein hydrolysate and glycerol + ammonium sulphate media on the composition and growth rate of Mycobacterium tuberculosis bcg grown in shaken culture for various periods were investigated. The bacteria were fractionated and the soluble, alkali-extractable, hot acid-soluble and residual fractions analysed for carbohydrate, RNA, DNA, free lipid, soluble amino compounds and soluble phosphates. The results indicate that several forms of growth restriction operated in these experiments: a progressive reduction in growth rate even in conditions when nutrients were not limiting, due to clumping of cells; a reduction in growth rate following any reduction in the amino acid content of the medium; a marked reduction in growth rate when the amino acid content of the medium fell below a critical level, or was replaced by ammonium ions. When the growth rate was reduced because of nutrient limitation, the carbohydrate content of the bacteria increased, but the pattern of accumulation varied with the experimental conditions. The RNA: protein ratio of the cells was little affected by growth rate.