Effects of Fertilization and Irrigation on the Seasonal Changes of Carbohydrate Reserves in Different Age-Classes of Needle on 20-Year-Old Scots Pine Trees (Pinus silvestris)

The effects of fertilization, irrigation or both on the seasonal changes of starch and soluble carbohydrates (glucose, fructose, myo-inositol, pinitol and sucrose) in needles of 20-year-old Scots pine trees (Pinus silvestris L.) were studied during three consecutive years. The starch content of the mature needles increased during spring and early summer to about 25% of dry weight. Neither fertilization nor irrigation affected the general pattern of starch accumulation during the spring. The starch reserves were mobilized when the shoot started to grow. Starch content decreased more rapidly in needles from fertilized than in those from unfertilized trees. The current needles from the control trees accumulated starch while they were still growing. The current needles of the fertilized trees did so to a lesser extent. The amount of starch was closely correlated to the air temperature and to the growth rate. Large amounts were found at low temperatures and low growth rates. The concentrations of soluble carbohydrates showed the well-known seasonal variation, with the highest value during the winter. The levels of sugars were nearly similar, irrespective of fertilization. An exception was sucrose, which was found in small quantities in needles from fertilized plots. Small amounts of sucrose were also found in growing current needles. The results are discussed in relation to growth limitation by assimilate availability and indicate that the ‘sink demand’ is the limiting factor.     

Changes in soluble carbohydrates and starch amounts during somatic and zygotic embryogenesis of Acca sellowiana (Myrtaceae)

Comparative analysis of zygotic and somatic embryogenesis of Acca sellowiana showed higher amounts of sucrose, fructose, raffinose, and myo-inositol in zygotic embryos at different developmental stages than in corresponding somatic ones. These differences were mostly constant. In general, glucose levels were significantly lower than the other soluble carbohydrates analyzed, showing minor variation in each embryo stage. Despite the presence of sucrose in the culture medium, its levels conspicuously diminished in somatic embryos compared with the zygotic ones. Raffinose enhanced parallel to embryo development, regardless of its zygotic or somatic origin. Analysis of the soluble carbohydrate composition of mature zygotic cotyledon used as explant pointed out fructose, glucose, myo-inositol, sucrose, and raffinose as the most important. Similar composition was also found in the corresponding somatic cotyledon. Total soluble carbohydrates varied inversely, decreasing in zygotic embryos and increasing in somatic embryos until the 24th d, at which time they increased rapidly about sixfold in zygotic embryos until the 27th d, a period coinciding with the zygotic proembryos formation. Such condition seems to reflect directly the variation of endogenous sucrose level, mainly because glucose and fructose diminished continuously during this time period. This means that, in terms of soluble sugars, zygotic embryo formation occurred under a situation represented by high sucrose amounts, simultaneously with low fructose and glucose levels, while in contrast, somatic embryo formation took place under an endogenous sugar status characterized by a substantial fructose enhancement. Starch levels increased continuously in zygotic embryos and decreased in somatic ones, the reverse to what was found in fructose variation. Starch accumulation was significantly higher in somatic torpedo and cotyledonary embryos than in the corresponding zygotic ones.     

The effect of season of growth on the chemical composition of cambial saps of Eucalyptus regnans trees

Summary Bark was stripped, at monthly intervals, from the stems of ten previously-unsampled trees of Eucalyptus regnans F. Muell. The exposed surfaces of inner phloem and outer xylem yielded phloem and cambial saps which were rapidly frozen. After freeze drying to determine the contents of water and dry-matter, the samples were extracted with 80% ethanol. The main components in this extract are low molecular weight carbohydrates and salts of inorganic acids. The carbohydrates comprise stachyose, raffinose, sucrose, galactinol, glucose, fructose, myo-inositol and galactose; sucrose is invariably the major component. The amounts of all components varied widely during the sampling period. Multiple regression analyses showed that season of growth has a significant effect on sucrose, glucose, fructose, total sugars and soluble dry-matter, maxima being recorded near the beginning of autumn and spring, and minima near the beginning of winter and summer; that oligosaccharide and myoinositol contents are significantly related to atmospheric temperature; and that rainfall has a significant effect on the hexose and total sugar contents, saps from the xylem surfaces being more affected than those from the phloem surfaces. The translocated photosynthates in E. regnans appear to be oligosaccharides of the raffinose family and sucrose. Significant negative correlations between oligosaccharides and both sucrose and myoinositol, and significant positive correlations between sucrose and both glucose and fructose, are consistent with enzymic hydrolysis and resynthesis of most di- and oligosaccharides. The biosynthetic demands of developing secondary tissues and/or the fluctuations in composition of sieve-tube assimilates appear to control the composition of the sugars in the saps. Oligosaccharides and sucrose may function as soluble reserve substances as well as translocated photosynthates. It is possible that myoinositolis a key component in the interconversion processes of the sugars; experiments with radioactive sugars tend to lend support to this contention, especially during winter conditions.     

Possible Roles of Methyl Glucoside andMyo-inositol in the Opening of Cut Rose Flowers

Methyl glucoside andmyo-inositol are present in all organs ofrose (Rosa hybridaL.). To investigate the possible role of thesecarbohydrates in the opening of cut roses, flowers with a 10,20 or 40-cm-long stem and a single flower bud (about 1.5 cmin diameter) were placed in water and flower opening and changesin sugar content in flowers and stems examined for 7 d. Thelonger the stem of the cut flower, the larger was the flowerdiameter. In stems, the concentration of carbohydrates, includingmethyl glucoside andmyo-inositol markedly decreased before floweropening. In petals, contents of glucose, methyl glucoside andmyo-inositolalso decreased before flower opening, but those of fructose,sucrose and xylose did not. When glucose and methyl glucosidewere added to the vase water (4%) flower opening was clearlypromoted; this was accompanied by an increase in methyl glucosideand fructose concentrations in petals. On the contrary,myo-inositolinhibited flower opening, and this was accompanied by an increaseinmyo-inositol and xylose concentrations in petals. These resultssuggest that methyl glucoside and/or its metabolites are transportedinto the petal cells, thereby lowering the osmotic water potentialand promoting flower opening.Myo-inositol is not readily metabolized,and exogenousmyo-inositol given at a high concentration mayact as an extracellular osmolyte, which inhibits water uptakeand flower opening.Copyright 1999 Annals of Botany Company Cut flowers, methyl glucoside,myo-inositol,Rosa hybrida,soluble carbohydrate.     

Soluble carbohydrates of Pinus sylvestris L. sapwood and heartwood

Summary The amounts of glucose, fructose, sucrose, arabinose/galactose, raffinose/stachyose and starch were investigated in the outer sapwood, innermost sapwood, transition zone and heartwood of four stems of Pinus sylvestris L. The samples were taken in October and the determination of the compounds was done enzymatically. It was not possible to distinguish arabinose from galactose and raffinose from stachyose. The amounts of glucose, fructose and sucrose were greatest in the outer sapwood and decreased gradually towards the innermost sapwood and the heartwood. In the outermost heartwood glucose, fructose and sucrose were only present in trace amounts. Raffinose/stachyose showed highest concentrations in the outer sapwood and decreased towards the heartwood. In contrast, the concentrations of arabinose/galactose increased towards the heartwood and the greatest amount was found in the inner heartwood. When identified by thin-layer chromatography (TLC), arabinose was found to be present in greater amounts than galactose. The amount of starch decreased markedly towards heartwood. However, the amounts of sugars in all the studied stems was very variable. The changes in the amounts of carbohydrates in the different zones of the stems and the possible relationships of these phenomena with heartwood formation are discussed.     

Contents of soluble carbohydrates in yellow lupin seeds maturated at various temperatures

The objective of this paper was to compare the levels of soluble sugars in seeds of yellow lupin cv. Juno matured at different temperatures. The temperature regimes applied were 1). 26 °C for 24 h (high temperature), 2). 24 °C for 12 h and 19 °C for the next 12 h (optimum temperature regime), 3). 26 °C for 16 h and 4 °C for the next 8 h (high-low temperatures). Six soluble carbohydrates (d-galactose, myo-inositol, sucrose, raffinose, stachyose and verbascose) were quantified. Seeds maturing at constant temperature 26 °C accumulated more raffinose (by 100 %) than seeds maturing at optimum temperature regime. Seeds maturing at high temperature accumulated less stachyose and verbascose than those maturing at optimum temperature conditions, the differences being 45 and 24 %, respectively. In seeds maturing at high-low temperature the level of raffinose decreased while the level of stachyose and verbascose increased, compared to those maturing at optimum conditions. The contents of sucrose, d-galactose and myo-inositol in seeds maturing at optimum temperatures was lower than in seeds maturing at both high and high-low temperature regimes. It was shown, that temperature conditions — constant high temperature, or physiologically optimal thermal oscillations (24 °/19 °C) or high-low temperature regime — differently affect the contents of six soluble carbohydrates in maturing seeds of yellow lupin.     

Formation of heartwood substances in the stemwood of Robinia pseudoacacia L. II. Distribution of nonstructural carbohydrates and wood extractives across the trunk

Summary The distributions of reserve carbohydrates and of three dominant heartwood extractives were determined in the trunkwood of Robinia pseudoacacia L. The trees were cut at different times of the year (September, November, January, and April). With the exception of the tree felled in January, all trunks exhibited highest contents of nonstructural storage carbohydrates (glucose, fructose, sucrose, and starch) in the youngest, outermost sapwood zone. With increasing depth of the trunk, the levels of carbohydrates decreased. At the sapwood-heartwood transition zone, only trace amounts of nonstructural carbohydrates were present. The heartwood itself contained no storage material. The wood zones of different ages of the trees cut in September, November, and January exhibited glucose/fructose ratios of approximately 1. In April, however, there was a shift to glucose. In the youngest sapwood the amounts of soluble sugars were higher in the earlythan in the latewood. Older zones of the sapwood and the sap-wood-heartwood transition zone showed the opposite behaviour. Three main wood extractives of Robinia were characterized and quantified: the flavanonol dihydrorobinetin (DHR), the flavonol robinetin (ROB) and a hydroxycinnamic acid derivative (HCA). Only DHR was present — in very low amounts — in the younger sapwood of all trunks investigated. Higher amounts (>1 mol/g dry weight) of this compound and the HCA were present in the sapwood-heartwood transition zone. DHR augmented within the heartwood up to a more or less constant level. HCA increased towards the heartwood and decreased again in the inner heartwood parts. ROB appeared in the innermost parts of the sapwood-heartwood transition zone and reached maximum values in older parts of the heart-wood. The results indicate that starch is hydrolyzed at the sapwood-heartwood boundary and thus represents a primary major source of hydroxycinnamic acid and flavonoid synthesis.Dedicated to Prof. Meinhart H. Zenk on the occasion of his 60th birthday     

Sorbitol and other carbohydrates in dormant apple shoots as influenced by controlled temperatures

The influence of controlled temperatures on levels of sorbitol and other carbohydrates was determined to provide further information on dormancy of apple trees (Malus sylvestris Mill.). For 3 years, 2-year-old “Red Delicious” apple shoots were collected from mature trees in an orchard at intervals during the autumn and winter, and shoots were stored for 6 hr to 1 week at temperatures from 18 to ?60 °C. Sorbitol and other carbohydrates were estimated in the sap or wood by gas chromatography.Controlled temperatures had a marked influence on the carbohydrate content of excised 2-year-old apple shoots. Levels of sorbitol in the sap were maximum at ?0.6 °C. The increase was greatest at the earliest sampling before complete hardening had occurred in each of the 3 years tested. Total sorbitol in the wood was less influenced by storage at various controlled temperatures than sorbitol in the sap. Levels of fructose, glucose, and sucrose in the wood were higher at temperatures below ?0.6 °C than at warmer temperatures. Levels of starch were usually inversely related to soluble sugars.     

Geographic differences on accumulation of sugars and polyols in locust eggs in response to cold acclimation

The accumulation of low molecular weight sugars and polyols is one of major mechanisms hypothesized to increase cold tolerance in overwintering insects. But little is known about whether these sugars and polyols are involved in geographic variation of cold tolerance. In this study, we investigated accumulation patterns of eight low molecular weight sugars and polyols of eggs in tropical and temperate populations of the migratory locust, which exhibits between-population variation in cold tolerance, in response to cold acclimation (5, 0 and −5 °C). Excluding erythritol, the other seven carbohydrates were identified as possible cryoprotectants in locust eggs. Basal maximal and minimal concentrations were 45 μg/g wet weight for trehalose and 0.59 μg/g wet weight for glycerol. Most sugars and polyols were elevated after a −5 °C exposure. In a tropical population, fructose, glucose, sorbitol and myo-inositol were significantly accumulated by low temperature treatments, but glycerol was not. In the temperate population, glycerol, glucose, mannitol, sorbitol, myo-inositol were significantly accumulated but trehalose did not increase. Our results suggest different accumulation patterns of these carbohydrates of locust eggs between tropical and temperate populations and highlighted possible roles for them in geographic variation of cold tolerance in the migratory locust.     

Concentration gradients of free sterols,steryl esters and lipid phosphorus in the trunkwood of Scot's pine (Pinus sylvestris L.)

The amounts of free sterols, steryl esters and lipid phosphorus were determined in the sapwood and heartwood of mature, and in the outer and inner sapwood of young Pinus sylvestris trees. In the mature trees (up to 70 years old) the heartwood contains significantly higher amounts of free sterols than the sapwood. No radial gradient can be demonstrated in the amounts of steryl esters. Lipids extracted from the sapwood contain higher amounts of phosphorus than those from the heartwood. Stems of young Pinus sylvestris trees (up to 13 years old) show in the inner sapwood higher amounts of both free sterols and steryl esters than the peripheral younger wood zone. The inner sapwood of the young stems shows slightly higher amounts of lipid phosphorus than the outer sapwood. The results indicate that Pinus sylvestris accumulates both free sterols and steryl esters in the stems at a very early stage of the life cycle. Sterol accumulation in the innermost parts of the stems seems not to depend on heartwood formation.     

Excess of exogenous nitrates inhibits formation of abnormal wood in the Karelian birch

The effect of exogenous nitrate on the sucrose-metabolizing enzyme activities—sucrose synthase (SS) and apoplastic invertase (ApInv)—in the xylem and phloem of the silver (Betula pendula Roth var. pendula) and Karelian (B. pendula var. carelica) birches (the latter is well known for its abnormal, patterned wood) has been studied. A stable correlation between the enzyme activities and deviations in the growth and development of stem vascular tissues during cambial growth has been demonstrated. Formation of the birch wood with a common structure is associated with high SS activity. In this case, the reaction yields UDP glucose, which is utilized mainly for synthesis of the cell wall components of vessels and fiber tracheids. As for the Karelian birch, the SS activity in the xylem formation zone is decreased, which complies with a higher sucrose level in the tissue. The excess sucrose is released into the apoplast to be cleaved by ApInv. The resulting hexoses induce storage metabolism, thereby increasing the amount of storage substances and the share of storage parenchyma cells in the xylem. As a result, the Karelian birch wood acquires large inclusions in the parenchyma, which render a characteristic pattern. A change in the ratio of SS to ApInv activities underlies a great variety in the degree of wood patterning observed in Karelian birch trees. In the common silver birch, the nitrate application increases the sucrose utilization via SS pathway, which results in an increase in wood growth. In the Karelian birch xylem, nitrates lead to a decrease in both the SS (a decrease in wood growth) and ApInv (a decrease in the amount of parenchyma, i.e., normalization of the wood structure). The sucrose metabolizing in the xylem decreases on the background of an increase in its utilization in the phloem, where both enzyme activities elevate. It is assumed that the fact that the Karelian birch distribution range is limited by rich soils can be determined by a shift from intensive apoplastic sucrose utilization zone towards the phloem caused by high doses of nitrogen nutrition.     

Quantification of Trends in Wood Production Within Trees of Silver Birch (Betula pendula Roth.)

Trends in rate and duration of wood production are analysedalong and between branches, and along main stems of silver birch(Betula pendula Roth.) trees (at early canopy closure and closedcanopy stages of growth). These data are discussed in relationto the control of knot size, log diameter and taper. To providea field guide to cambial reactivation, progress of vessel productionhas been related to stages of leaf expansion.Copyright 1994,1999 Academic Press Betula pendula (Roth.), silver birch, cambial activity, wood production, wood quality, vessel production     

Chemical factors affecting the brown-rot decay resistance of Scots pine heartwood

The cell wall chemistry (amount of hemicellulose, f-cellulose, and total lignin) and the concentration of extractives (total acetone-soluble extractives, resin acids, pinosylvins and the total phenolics quantified as tannin acid equivalents) were studied in brown-rot resistant and susceptible juvenile heartwood of Scots pine (Pinus sylvestris L.). The study material consisted of a total of 18 trees from two 34-year-old progeny trials at Korpilahti and Kerimäki. The trees were selected from among 783 trees whose decay rate had previously been screened in a laboratory test using a brown-rot fungus, Coniophora puteana. Samples from neither location showed any significant difference in the concentration (mg/cm³) of hemicellulose, f-cellulose and total lignin between the decay resistant and susceptible trees. At both locations only the concentration of total phenolics was higher in the decay-resistant heartwood than in the decay-susceptible heartwood. At Korpilahti, the amount of acetone-soluble extractives and the concentration of pinosylvin and its derivatives were higher in the resistant than in the susceptible trees.     

Inositol and sugars in adaptation of tomato to salt

Tomato (Lycopersicon esculentum Mill. cv New Yorker) plants subjected to 100 millimolar NaCl plus Hoagland nutrients exhibited a pattern of wilting, recovery of turgor, and finally recovery of growth at a reduced level, which required 3 days. During the nongrowing, adaptation phase there were immediate increases in free hexoses and sucrose which declined to near control levels as growth resumed. There was a steady increase in myo-inositol content which reached its maximal level at the time of growth resumption. The myo-inositol level then remained elevated for the remainder of the experiment. Myo-inositol constituted two-thirds of the soluble carbohydrate in leaves and three-fourths of the soluble carbohydrate in roots of salt-adapted plants. Plants which were alternated daily between salt and control solutions accumulated less myo-inositol and exhibited less growth than the continuously salt-treated plants. In L. pennellii and in salt-tolerant and salt-sensitive breeding lines selected from L. esculentum × L. pennellii BC(1) and F(8), myo-inositol content was highest in the most tolerant genotypes, intermediate in the normal cultivar, and lowest in the sensitive genotype after treatment with salt.     

Carbohydrate Metabolism in Drought-Stressed Leaves of Pigeonpea (Cajanus cajan)

Pigeonpea is a tropical grain-legume, which is highly dehydrationtolerant. The effect of drought stress on the carbohydrate metabolismin mature pigeonpea leaves was investigated by withholding waterfrom plants grown in very large pots (50 kg of soil). The moststriking feature of drought-stressed plants was the pronouncedaccumulation of D-pinitol (1D-3-methyl-chiro-inositol), whichincreased from 14 to 85 mg g^–1 dry weight during a 27d stress period. Concomitantly, the levels of starch, sucroseand the pinitol precursors myo-inositol and ononitol all decreasedrapidly to zero or near-zero in response to drought. The levelsof glucose and fructose increased moderately. Drought stressinduced a pronounced increase of the activities of enzymes hydrolysingsoluble starch (amylases) and sucrose (invertase and sucrosesynthase). The two anabolic enzymes sucrose phosphate synthase(sucrose synthetic pathway) and myo-inositol methyl transferase(pinitol synthetic pathway) also showed an increase of activityduring stress. These results indicate that pinitol accumulatedin pigeonpea leaves, because the carbon flux was diverted fromstarch and sucrose into polyols. Key words: Drought, polyols, pinitol, sucrose, starch, pigeonpea     

Phytate metabolism in Petunia pollen

Phytic acid has been detected in the anthers of young flower buds of Petunia hybrida, the amount increasing slowly as the flower develops until anther dehydration, when there was a more rapid increase in phytic acid content. In mature pollen, the phytic acid content was found to be 2.0 % by weight, of which 90 % was water soluble, while free myo-inositol was a relatively low 0.06 % by weight. Breakdown of phytic acid was initiated soon after pollen germination began, and its degradation products, myo-inositol and inorganic phosphate, were rapidly mobilized for phospholipid and pectin biosynthesis. Both are in high demand during pollen tube elongation. Utilization of myo-[2-³H]inositol for phospholipid biosynthesis was about five times that for pectin synthesis during the first few hours of pollen germination. The label in the phospholipid was identified as the myo-inositol moiety of phosphaltidylinositol, while the pectin material contained predominantly labelled arabinose, with smaller amounts of label in galacturonic acid, glucose and xylose. A chase experiment showed that the myo-inositol moiety of phosphatidylinositol was subject to a relatively rapid turnover, while the label in pectin was not. Labelling germinating pollen with [³²P]orthophosphate gave label in phosphatidic acid, phosphatidylinositol, phosphatidylethanolamine and phosphatidylcholine of the phospholipids. Phosphatidylinositol contained 30 % of this label initially, a proportion which declined to 10 % over longer periods of germination.     

Metabolism of myo-Inositol and growth in various sugars of suspension-cultured tobacco cells

Tobacco (Nicotiana tabacum L.) cells were cultured in a liquid medium which contained sucrose as a source of carbon and energy. Various cell-wall constituents and wall precursors (L-arabinose, D-xylose, D-galactose, D-mannose, D-glucuronate, myo-inositol) were added to cells growing in this medium to by-pass possible rate-limiting steps in the relevant metabolic pathways. None of these compounds stimulated growth as measured by increase in fresh weight; myo-inositol did cause a slight increase and L-arabinose a decrease in dry weight accumulation compared to controls grown on sucrose only. Although myo-inositol was not needed for rapid growth, tracer level amounts of [2-³H]myo-inositol were rapidly absorbed and metabolized. Label was incorporated into the uronide and pentose residues of cell walls and exocellular polysaccharide.     

Tarsal taste neurons of Helicoverpa assulta (Guenée) respond to sugars and amino acids, suggesting a role in feeding and oviposition

Helicoverpa assulta and Helicoverpa armigera are sibling species with different host-plant ranges. We have previously reported electrophysiological and behavioral responses of H.armigera to sugars and amino acids. Here we describe a parallel study performed on H. assulta and compare the results obtained with the two species. In females, fourteen gustatory chemosensilla, identified on one ventrolateral side of the fifth tarsomere were stimulated with sucrose, glucose, fructose, maltose, myo-inositol, and the twenty common amino acids, using the tip-recording technique. The taste receptor neurons in eight chemosensilla were identified sensitive to the sugars, myo-inositol, Lys, Glu, Arg, Trp, and Ser which all induced proboscis extension reflex (PER) when tarsi were stimulated. There was a positive correlation between electrophysiological activities and PER responses triggered by sucrose. No stimulatory effect on oviposition was observed with sugar or amino acid mixtures. In males, three chemosensilla showed responses to the four sugars, but generally weaker than in females. The major difference of the two species was the variety of amino acids triggering electrophysiological responses. The stimulatory effect of sugars and amino acids on H.assulta was also generally weaker than that on H. armigera.     

Changes in Sugar Content during Cold Acclimation and Deacclimation of Cabbage Seedlings

The relationship between freezing tolerance and sugar contentin cabbage seedlings was investigated. Seedlings exposed tonon-freezing low temperature (5 °C) acquired freezing tolerancedown to -6 °C. The degree of freezing tolerance increasedwith duration of exposure to low temperature (up to 10 d). Sucrose,glucose, fructose and myo -inositol were detected as solublesugars in cabbage leaves, and all soluble sugars, except formyo -inositol, and starch increased gradually during cold acclimationsuch that their levels were positively correlated with the degreeof freezing tolerance. The induced freezing tolerance was attributednot to ontogenetic changes but to cold acclimation. However,the induced freezing tolerance was lost after only 1 d of deacclimationat control temperatures, and this change was associated witha large reduction in sugar content. These results reveal that the sugar content of cabbage leavesis positively correlated with freezing tolerance. Brassica oleracea L.; cabbage; cold acclimation; deacclimation; freezing tolerance; sugars