Changes in the Content of Amino acids, Carbohydrates and Adenine Nucleotides following Budding in the Hardwood Stems of Mulberry Plants (Morus alba)

Quantitative changes in the free amino acids, sugars and adeninenucleotides in the hardwood stems of mulberry plants (Morusalba L.) were followed during bud opening. Following this, thestarch and ATP content decreased rapidly. The value of the adenylateenergy charge, ATP+; ADP/ATP + ADP+AMP, or ATP/ADP ratio becamelower. Asparagine, proline and arginine existed prominentlyat the onset of budding. After budding, the content of prolineand asparagine decreased consecutively, but that of arginineincreased initially and then decreased. Thus, the fluctuationsin the carbohydrate and amino acids metabolism in the hardwoodstems caused by budding was characterized by a rapid decreasein energy and carbohydrates reserves, and a concurrent decreasein proline and asparagine. The conversion of asparagine to arginineis also presumed to have taken place at the same time. Morus alba, mulberry, amino acids, carbohydrates, adenine nucleotides     

Total nitrogen and free amino acids in Morus alba stems from autumn through spring

During leaf senescence and abscission, total nitrogen in leaves of mulberry ( Morus alba L. ev. Shin-ichinose) declined substantially whereas total nitrogen in buds, bark and stem wood increased markedly, suggesting translocation of nitrogen from senescent leaves in the autumn. After leaf abscission the winter buds and stems remained almost unchanged with respect to fresh and dry weight and total nitrogen until bud break in spring. In burst buds these parameters then increased drastically during the new growth while they decreased markedly in stems. Free arginine in the stem bark accumulated in parallel with the accumulation of total nitrogen in buds and stems in the autumn. Accumulation of proline in the wood, bark and buds also started in October but continued even after leaf-fall, increasing until mid-January (wood), mid-February (bark) and the new growth (buds). Prior to and in the early stage of bud break, proline in bark and wood decreased significantly and arginine in stem bark decreased slightly. Simultaneously, proline and arginine in the dormancy-releasing buds and asparagine, aspartic acid and glutamic acid in the buds and stems increased appreciably, suggesting that this increase in free amino acids was mainly derived from free amino acids (proline and arginine) stored in stems. The resulting marked decrease in total nitrogen and the drastic increase in asparagine in the stems and sprouting buds/new shoots were primarily due to a breakdown of protein stored in stems.     

Changes in nitrogen levels and free amino acids in rooting cuttings of mulberry (Moms alba)

Total and protein nitrogen in bark and wood of parent stems of mulberry ( Morns alba L. cv. Ichinose) decreased readily and to the same extent during leafing-out of the buds, but the decrease in wood was less marked than in bark. Simultaneously, soluble nitrogen in both bark and wood also declined but the depletion was less marked than that of total and protein nitrogen. During the same period total nitrogen in the new shoots and adventitious roots increased drastically; however, the increase in total nitrogen in the growing parts during rooting was almost the same as the decrease in total nitrogen in the parent stems. Proline, the prevalent amino acid in wood and bark of the parent stems, decreased drastically during rooting, whereas during the same period asparagine in the developing buds, callus and adventitious roots increased markedly and became the predominant amino acid. The amount of arginine was relatively high in bark of the parent stems but Low in wood and the buds. The level of arginine in bark decreased considerably during the experiments (as did that of proline). The results suggest that the nitrogen required by the growing parts (sinks) in the rooting cuttings comes mainly from protein breakdown in bark of the parent stems (source), although stored protein in wood (source) and soluble nitrogen in bark and wood (sources) also play a part in storage of nitrogen. Asparagine is suggested to be the main nitrogen transport compound in the new growth of the tree and the initiating roots of cuttings.     

Free amino acids and total nitrogen during shoot development in Scots pine seedlings

The concentration of free amino acids and total nitrogen was studied in needles, stems and roots of seedlings of Pinus sylvestris L. for five weeks during the second growth period ("summer"). In one group of seedlings the source/sink relation was disturbed through removal of the terminal buds. The seedlings were cultivated in artificial year-cycles in a climate chamber.
Total nitrogen increased in needles and sterns of intact seedlings in the beginning of the "summer" and decreased during shoot growth. In seedlings, from which the buds had been removed, nitrogen remained at high levels in the primary needles and accumulated in steins and roots. The results are consistent with utilization of nitrogen in older needles and in the stem during shoot elongation.
The pool of free amino acids increased in the beginning of the "summer" and decreased after bud break in primary needles, stems and roots. Arginine and glutamine, in the roots also asparagine, were the dominating amino acids (amides included). Together, these compounds (plus glutamate and aspartate) contributed about 90% of the nitrogen in the amino acid pool in all organs. In primary needles and in the stem, arginine predominated at the end of hardening (75–85% of the amino acid nitrogen). Free amino acids contributed at most ca 10% of the total nitrogen in primary needles, where the ratio of free amino acid nitrogen: total nitrogen was highest at the end of dormancy and in the early "summer". Free amino acids accumulated after bud removal in primary needles and especially in stems and roots. Glutamine became relatively more dominant than arginine in the different organs.
The observations are consistent with the role of arginine and glutamine for storage and transport of nitrogen in conifers. Because of the low concentrations of amino acid nitrogen in the primary needles, arginine is not considered a major nitrogen reserve in needles of Scots pine seedlings.     

Composition and Distribution of Free Amino Acids in Flatpea (Lathyrus sylvestris L.) as Influenced by Water Deficit and Plant Age

Drought-stressed flatpea (Lathyrus sylvestris L.) plants from8 to 22 weeks old were analysed for nitrogen, soluble proteinand free amino acids. An increase in nitrogen and free aminoacid concentrations and a decrease in soluble protein levelwere observed in roots of plants up to 16 weeks old. The cumulativeconcentration of free amino acids increased with drought stress.Tissue concentrations of 2, 4-diaminobutyric acid (1.6–2.6%of the dry weight) were highest in leaves. Levels increasedsteadily, nearly doubling, in leaves and stems between weeks10 and 16. Levels in drought-stressed leaves were, on average,11.9% higher than those of controls. Estimated concentrationsof a mixture of 4-aminobutyric acid and an unknown amino acidwere highest in stems, increased in this tissue with age andtended to increase in stems and leaves and decrease in rootsin response to water deficit. Levels of the mixture of homoserineand another unidentified amino acid were not influenced by ageor water status of the plants. Root concentrations of asparagine,arginine, glutamine, aspartate, and another prominent, unidentifiedamino acid increased with plant age and reached a peak at thetime of flowering (14 to 18 weeks). Only the concentration ofthe unknown compound was elevated following drought stress.Concentrations of valine, isoleucine, leucine, phenylalanine,and methionine also increased during this period and were elevatedin drought-stressed plants. Proline levels increased with plantage and drought stress, but proline accounted for only about10% of the total free amino acids in the drought-stressed plants. Key words: 2, 4-Diaminobutyric acid, drought, flatpea     

Changes in the Levels of Free Amino Acids in Various Regions of Cuscuta during Growth

The angiospermous plant parasite Cuscuta derives reduced carbonand nitrogen compounds primarily from its host. Free amino acidsalong Cuscuta vines in three zones, viz., 0 to 5 cm, 5 to 15cm, and 15 to 30 cm, which in a broad sense represent the regionof cell division, cell elongation and differentiation and vasculartissue differentiation respectively, were quantitatively estimated.The free amino acid content was the highest in the 0 to 5 cmregion and progressively decreased along the posterior regionsof the vine. The haustorial region showed the lowest contentof free amino acids. In general, the free amino acid contentin samples collected at 7 p.m. was found to be higher than thatin the samples collected at 7 a.m. Three basic amino acids,histidine, the uncommon amino acid -hydroxyarginine, and arginineconstituted more than 50% of the total free amino acids in allthe zones studied except the haustorial region. Aspartic acidand glutamic acid constituted the major portion in the acidicand neutral fraction of amino acids. Glutamine, asparagine,threonine, and serine were eluted together and occurred in substantialamounts. -Hydroxyarginine constituted the largest fraction inthe cut end exudate of Cuscuta and presumably appeared to bethe major form of transport amino acid. -Hydroxyarginine wasalso a major constituent of the basic amino acids in Cuscutavines parasitizing host plants from widely separated families,suggesting that this amino acid is a biosynthetic product ofthe parasite rather than that of the hosts. Also, U-¹⁴C argininewas converted to -hydroxyarginine by cut Cuscuta vines, suggestingthat -hydroxyarginine is synthesized de novo from arginine byCuscuta. (Received March 30, 1987; Accepted June 7, 1988)     

Origin of Foliar Nitrogen and Changes in Free Amino-Acid Composition and Content of Leaves, Stubble, and Roots of Perennial Ryegrass During Re-growth after Defoliation

Nitrogen re-mobilization and changes in free amino acids werestudied as a function of time in leaves, stubble, and rootsduring ryegrass (Lolium perenne L.) re-growth. Experiments with¹⁵N labelling clearly showed that during the first days nearlyall the nitrogen in new leaves came from organic nitrogen re-mobilizedfrom roots and stubble. On the days of defoliation, stubblehad the highest content of free amino acids with 23 mg per gdry weight against 15 mg and 14 mg in leaves and roots, respectively.The major amino acids in leaves were asparagine (23% of totalcontent in free amino acids), aminobutyrate, serine, glutamine,and glutamate (between 7% and 15%) whereas in roots and stubblethe contribution of amides was high, especially asparagine (about50%). Re-growth after cutting was associated with a rapid increaseof the free amino acid content in leaves, with a progressivedecrease in roots while stubble content remained virtually unchanged.In leaves, asparagine increased from the first day of re-growth,while the aspartate level remained unchanged and glutamine increasedstrongly on the first day but decreased steadily during thenext few days of re-growth. Asparagine in stubble and rootschanged in opposite directions: in stubble it tended to increasewhereas in roots it clearly decreased. In contrast, stubbleand roots showed a similar decrease in glutamine. In these twoplant parts, as in leaves, aspartate remained at a low level.Results concerning free amino acids are discussed with referenceto nitrogen re-mobilization from source organs (stubble androots) to the sink organ (regrowing leaves). Key words: Lolium perenne L, re-growth, nitrogen, free amino acids, glutamine, asparagine     

Effect of {alpha}-Naphthalene Acetic Acid on Variations in Free Amino Acid Contents in Developing Fruits of Capsicum annuum L.

Capsicum annuum seeds were pretreated with three concentrationsof -naphthaleneacetic acid (NAA). The fruits of the controland treated plants showed differences in the quantities of freeamino acids during three developmental stages. From a relativelyhigh amount of total free amino acids in the early phase offruit development, there was lowering in the mid-phase and furtherlowering in the terminal phase. There were eight prominent ninhydrin-reactingspots which were identified as tryptophan, glycine, glutamicacid, valine-methionine, -aminobutyric acid, leucine(s), alanine,and aspartic acid and eleven trace spots attributable to tyrosine,serine, lysine, asparagine, cystine, thrconine histidine, phenylalanine,arginine, glutamine, and ornithine. Hormone treatment tendedto decrease the total amino acids in the early- and mid-phasesof fruit development compared with the control fruits. Asparticacid was present in greater quantities in the treatments thanin the controls. In the terminal phase, the treated fruit didnot show any significant change in the total free amino acidcontents. The significance of the NAA-included variation infree amino acids is discussed. Capsicum annuum, amino acids, -naphthaleneacetic acid     

Seasonal Variation of Nitrogenous Compounds in Components of the Kiwifruit Vine

Free amino acids in 6-year-old kiwifruit vines [Actinidia deliciosa(A. Chev.) C. F. Liang et A. R. Ferguson] were measured overthe course of 1 year using components obtained from whole-vineharvests. Tissues examined from the perennial structure consistedof the wood and cortex of structural roots, wood and bark ofstem, leader and 1-year-old fruiting canes. Free acids in theannual growth (fine roots, flowers, fruit, leaves and non-fruitingshoots) were also measured. The range of amino acids extracted indicated that kiwifruitconforms to a conventional pattern of nitrogen metabolism. Acidspresent in greatest concentration depended on tissue type andsampling time. In perennial components and fine roots, arginineand glutamine were the predominant species, followed by gamma-aminobutyrate,aspartate, glutamate, alanine and valine. Generally, maximumconcentrations of all free acids were measured in a 10-weekperiod around budbreak. These same acids, plus asparagine, serineand threonine, were also prevalent in annual growth. In leaves,flowers and non-fruiting shoots, concentrations were greatestin the young tissue and declined with age. By contrast, concentrationsof arginine, asparagine and glutamine in fruit peaked approximately10 weeks after anthesis, subsequent to the cell division phaseof growth. During the year, free arginine averaged 44, 48 and 58 % of thetotal N in the fine roots, and the cortex and wood of structuralroots, respectively (the quantity of total N and amino-N inother components of the structural framework was much less thanthat in root tissue). Arginine was the principal N-containingspecies measured in xylem sap vacuum-extracted from 1-year-oldcanes over winter. During the period of vegetative growth, however,glutamine and nitrate were the principal N-transport forms present.The study highlights the importance of the fine root systemas the primary location of nitrogenous reserves in this plantand identifies arginine as the dominant N-storage form. Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson, amino acid composition, kiwifruit, nitrogen, whole-plant harvesting     

Changes in the Nitrogen Compounds of Xylem Sap of Mulberry (Morus alba L.) during Regrowth after Pruning

Changes in fresh and dry weights and total nitrogen in stemsections of mulberry (Morus alba L.) and seasonal fluctuationin the amounts of exudate, pH and nitrogen compounds in xylemsap from cut stems of the plant after pruning have been studied.The amount and concentrations of nitrogen compounds in the sapchanged during the experimental period, but nitrate-nitrogenand ammonia-nitrogen were constant constituents, and asparaginewas quantitatively the major organic nitrogen compound. Smalleramounts of glutamine, aspartic acid and glutamic acid were alsofound, but no ureides or alkaloids were detected. Relationshipsbetween growth and nitrogen in xylem sap of mulberry and therole and importance of asparagine in nitrogen metabolism arediscussed. Morus alba L., mulberry, asparagine, exudates, nitrogen, amino-acids, xylem sap, stem growth, aspartic acid, glutamic acid, ureides     

The Influence of Nitrogen Nutrition on the Accumulation of Free Amino Acids in Root Tissue of Urtica dioica and their Apical Transport in Xylem Sap

Urtica dioica plants were grown on a nitrogen supply of 3, 15and 22 mM with nitrate and ammonium as nitrogen source. In contrastto nitrate reductions amino acid synthesis occurred in roottissue. At 3 mM ammonium obviously the amino acids were rathertransported via xylem upwards to the shoots than stored in theroots. Particularly increased ammonium supply led to stimulatedstorage of free amino acids in the roots, mainly as asparagineand arginine. In xylem asparagine was the dominant nitrogentransporting compound, while arginine was hardly translocated.With the enhancement of nitrogen supply, the second amide, glutamine,became more and more important with respect to the transportof nitrogen. (Received September 3, 1984; Accepted November 2, 1984)     

Comparison of Free and Bound Amino Acids in White and Green Tissues of Variegated Tobacco Plants

Qualitative and quantitative comparisons of free and bound aminoacids and soluble proteins in white and green tissues of variegatedtobacco leaves were made. White tissue contained more free andless bound amino acids than green tissue, although the sum ofthe total amino acids did not differ significantly between thetwo tissues. The major free amino acids in white tissue wereglutamine and asparagine, whereas those in green tissue wereglutamic acid, aspartic acid and -aminobutyric acid. The contentsof fraction 1 protein and 70 S ribosomes in white tissue werenegligible in comparison with those found in green tissue, butthe amounts of other soluble protein components and the 80 Sribosomes were at the same level in both tissues. (Received October 21, 1981; Accepted January 28, 1982)     

Changes in the Contents of Free and Protein Amino Acids in Tobacco Seeds and Placentae during Maturation

Changes in the levels of protein and free amino acids in theseeds and placentae of Nicotiana tabacum were studied duringseed development. Seed maturation was completed 24 days afteranthesis. During maturation, protein rapidly accumulated inthe seeds between the 6th and 18th day, along with an appreciablecompositional change in the protein amino acids as the proportionsof glutamic acid and arginine increased. The amount of freeamino acids in the seeds gradually decreased throughout maturation.The major free amino acid on the 6th day after anthesis wasglutamine, which then drastically decreased between the 6thand 12th day with increases of glutamic acid, proline, arginineand alanine. The latter amino acids decreased thereafter untilthe 24th day. On the other hand, the amount and composition of the proteinsin the placentae did not change significantly throughout seedmaturation. In the early stage of development, the major freeamino acids in the placentae were glutamine, asparagine andglutamic acid, while in the later stage asparagine was mostabundant. (Received March 12, 1982; Accepted August 16, 1982)     

Composition of Amino Compounds Transported in Xylem of Casuarina sp.

Seedlings (180-d-old) of Casuarina cunninghamianaM L., C. equisetifoliaMiq. and C. glauca Sieber inoculated with each of two differentsources of Frankia, were analysed for translocated nitrogenouscompounds in xylem sap. Analyses were also made on sap fromnodulated and non-nodulated plants of C. glauca grown with orwithout a range of levels of combined nitrogen. Xylem exudateswere collected from stems, roots, and individual nodules ofnodulated plants and from stems and roots of non-nodulated plants.While the proportional composition of solutes varied, the samerange of amino compounds was found in xylem sap from the threedifferent symbioses. In C. glauca asparagine was the major aminoacid in the root sap followed by proline, while in symbioticC. cunninghamiana arginine accounted for more than 25% of theamino compounds. Citrulline was the major translocated productfound in the stem exudate of symbiotic C. equisetifolia. Increasingconcentrations of ammonium nitrate in the nutrient solutionresulted in increasing levels of free ammonia and glutaminein xylem sap from stems of nodulated and non-nodulated C. glauca,but there was relatively little change in the prominent solutes,e.g. citrulline, proline, and arginine. The composition of nitrogenoussolutes in stem or root exudates of C. glauca was similar tothat of exudate collected from individual nodules and on thisbasis it was not possible to distinguish specific products ofcurrent N₂ fixation in xylem. The main differences in N solutecomposition between the symbioses were apparently due to hostplant effects rather than nodulation or the levels of combinedN. Also, the data indicate that the use of the proportion ofN in sap as citrulline (or indeed any other organic N solute)could not be used as an index of nitrogen fixation.     

Influence of Several Growth Regulators and Amino Acids on in vitro Organogenesis of Torenia fournieri Lind.

The effects of several growth regulators and amino acids onin vitro organogenesis of Torenia fournieri Lind. were determinedusing internodal segments. Treatment with 2,4-D¹ resulted innodular callus formation, while NAA and IAA induced roots constantlybut much less frequently shoot buds. Individually BA, zeatin,and 4-PU induced bud formation, but these shoot buds did notdevelop further. Formation of buds by cytokinin was influencedby a simultaneous application of NAA or 2,4-D, but not of IAA,its degree being reduced when BA was simultaneously appliedwith NAA or 2,4-D. When zeatin or kinetin was added with NAA,numerous roots were induced. The effects of various L-amino acids on in vitro organogenesiswere also investigated using the defined medium in which KNO₃was a principal source of nitrogen. The formation of buds wasconsiderably stimulated by alanine and asparagine, and slightlyby glutamic acid in the medium containing both NAA and BA, inwhich bud formation was easily induced. On the other hand, allamino acids except for glutamic acid and aspartic acid inhibitedroom formation in this medium. Root formation was greatly stimulated by proline, alanine, glutamine,glutamic acid, and aspartic acid, and slightly by arginine andtryptophan in the medium containing NAA but no BA. Glutamicacid and aspartic acid also enhanced bud formation in this medium.     

Amino Acid Pools in Herbaceous Plants at the Wintering Stage and at the Beginning of Growth

Free amino acids in 40 herbaceous perennial plants were analyzedunder natural conditions. From the major amino acid contentat the wintering stage, the pools were separated into the followingfive types: 1) a group which accumulated arginine (20 plantsout of 40); 2) a group which accumulated arginine and proline(9 plants); 3) a group which accumulated glutamate and glutamine(3 plants); 4) a group which accumulated asparagine (4 plants);and 5) a group which accumulated proline (4 plants). Changesin the amino acid pools in the plants occurred under snow duringwintering for about five months. Particularly, asparagine wasno longer the major amino acid in the group which had accumulatedit in fall. There was a tendency for the glutamine content toincrease, suggesting that NH₃ is utilized for the synthesisof the amide. Also, the relative concentrations of almost allthe free amino acids increased several-fold, which was indicativeof the occurrence of biosynthetic processes of general aminoacids during wintering. As the mobile fractions of stored nitrogen,the amino acids appeared to contribute to the initial stageof rapid growth in early spring. (Received August 4, 1986; Accepted November 17, 1986)     

Identification of Flavones in Thirteen Liliaceae Species

Changes in the levels of free and protein amino acids in the callus of Hiproly barley were studied during differentiation. Adventitious roots were formed in the callus after 90 days of cultivation on modified White’s medium containing 1 μm indoleacetic acid (IAA) and 200 μm adenine sulfate, and callus placed on Murashige–Skoog’s medium without plant hormones formed adventitious roots after 30 days of cultivation. During differentiation, protein amino acids in the callus decreased, then increased, without an appreciable compositional change in the protein amino acids. The amount of free amino acids in the callus increased with root formation. The major free amino acids during differentiation were glutamine, asparagine, alanine, and proline. Glutamine increased until roots were found in the callus after cultivation. Asparagine gradually increased during differentiation.     

Seasonal Dynamics of Nitrogenous Compounds in a Nitrophilic Weed II. The Role of Free Amino Acids and Proteins as Nitrogen Store in Urtica dioica

The free amino acid fraction, representing the most importantnitrogen store in the overwintering below ground plant partsof Urtica dioica, consisted mainly (up to 80%) of asparagineand arginine. While asparagine was dominant in rhizomes, upto one year old, argrnine was specifically accumulated in theolder rhizomes and roots. In spring first the nitrogen storedin asparagine and with a delay of about three weeks that inarginine was mobilized and translocated to the rapidly growingshoots. Proteins may function as nitrogen store too, in particularin the case of the seeds. In the below ground organs, however,a special storage protein, rich in amides and/or arginine, whichwould correspond to the large quantities of these amino acidsin the overwintering organs, could not be detected. (Received September 3, 1984; Accepted November 2, 1984)     

Seasonal Changes in Nitrogen Fractions of Coptis japonica, a Temperate Forest Evergreen Chamaephyte, and their Ecological Implications

Seasonal changes in several forms of nitrogen were investigatedin Coptis japonica, an evergreen rosette hemicryptophyte intemperate deciduous forest. The concentration of total nitrogenin rhizomes and roots decreased during the period of new shootgrowth from winter to spring. In the rhizomes, total solubleprotein stored by early summer decreased gradually until winter,coupled with an increase in free amino acids. Nitrogen was largelystored in free amino acids in the roots, especially during summer.The total soluble protein in current-year leaves decreased fromspring to summer and then increased during winter. The seasonalchanges in nitrogen components were coincident with the changein light-saturated photosynthetic rates recorded in a previousstudy. The ratio of total soluble protein to total nitrogendecreased from spring to summer and then increased from latesummer to winter in the current-year leaves. In contrast, chlorophyllcontent and the ratio of chlorophyll to total nitrogen werehigher in summer than in other seasons. The results indicatethat nitrogen was used in a manner that better utilizes thevery weak light in summer and the higher light intensities inother seasons. The major component of the free amino acid poolwas asparagine, in every organ throughout the season, exceptfor the senescent leaves. Since asparagine has a high N:C ratio,we suppose that the asparagine-dominated amino acid pool isadvantageous in the carbon-limited environment of the forestfloor.Copyright 1994, 1999 Academic Press Free amino acid composition, total nitrogen, total soluble protein, photosynthesis, evergreen hemicryptophyte     

Seasonal Changes of the Metabolites in the Leaves, Bark and Xylem Tissues of Olive Tree (Olea europaea. L) I. Nitrogenous Compounds

The changes of total nitrogen and free amino compounds wereexamined in leaves, bark and xylem tissues of olive tree duringa complete annual cycle. In leaves total nitrogen decreasedin spring/early-summer but reached the highest level in autumn-winterperiods. In bark tissues total nitrogen fluctuations were mainlyrelated to the periodical cambial activities. In xylem tissuestotal nitrogen was detected in low levels with no fluctuationsover the year. The free amino compounds in leaves showed seasonalpeaks during the spring and autumn stem elongations, while aconsiderable restriction of their levels was detected in summer.Glutamate, aspartate, proline, alanine, serine and -aminobutyrateare the predominant amino acids detected in leaves. Glutamateand aspartate increased considerably in spring and autumn periodsbut disappeared in summer. Proline remained almost unchangedover the year. Alanine, in addition to the spring and autumnfluctuations, also fluctuated in summer, -aminobutyrate wasdetected at highest levels in winter. In bark tissues, the patternof fluctuations and the composition of the free amino compoundswere similar to those of leaves. In xylem tissues free aminocompounds were detected in high levels over the year exceptfor the drops in spring and summer cambial activity periods.Xylem was the most important reservoir for the readily transportablesoluble nitrogen being accumulated during the maturing of theproduced new xylem. Arginine, glutamine, alanine, glutamate,aspartate, serine, -aminobutyrate and proline are the most prevalentamino compounds in xylem. Arginine and glutamine showed extensiveinterchanges. Arginine increased in autumn while glutamine andalanine showed low levels in the same period. Olive tree (Olea europaea L), amino acids