bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential attachment by conidia of the endophyte, Discula umbrinella (Berk. & Br.) Morelet, to host and non‐host surfaces
Authors: TOTI L. , VIRET O. , CHAPELA I. H. , PETRINI O. 
Published: April 2006

SUMMARYDifferential attachment of conidia to leaves of different species (host and non‐host) has been observed in the endophytic fungus, Discula umbrinella (Berk. & Br.) Morelet, a deuteromycete known to cause occasional epidemics of anthracnose in beech stands. On beech leaves, attachment gradually increased over 24 h and reached a maximum after 16–24 h; there were small differences in attachment between conidia suspended in water and those in HEPES buffer. The range of variation of results obtained with conidia suspended in HEPES was smaller but the adhesion was clearly enhanced. The adhesion of conidia to the host surface was highest at pH 5, and decreased with increasing pH. Heat and chemical treatments significantly reduced attachment. Two factors (or groups of factors) are likely to be involved in the recognition process. The first is heat‐labile, the second one could be a non‐protein molecule present on the conidial surface and actively recognized by the host. The physiological similarity between endophytes and other symbionts is briefly discussed.
Fructan biosynthesis in excised leaves of Lolium temulentum L.
Authors: CAIRNS ANDREW JOHN 
Published: April 2006

SUMMARYLeaves of Lolium temulentum L. were induced to accumulate fructan by excision and continuous illumination. Enzyme extracts were prepared and protein was concentrated by precipitation with ammonium sulphate at 100% saturation. The preparation was incubated at a protein concentration equivalent to 3‐4 g f.wt of tissue cm‐3 with sucrose at an initial concentration of 400 mol‐3. The preparation catalyzed the synthesis of large fructans of apparent degree of polymerization (DP) ⩽20, based upon comparison with the chromatographic mobilities of oligoinulins on thin‐layer chromatography (TLC). The products were formed at a rate approximating to rates of fructan accumulation in leaf tissue. The overall pattern of in vitro products, when separated on TLC, resembled that of the native leaf fructans though the relative abundances of some of the products differed from the in vivo pattern. The reaction did not catalyze the formation of the high molecular weight fructans (Mr > 3 kDa; DP > 20) characteristic of this tissue. Equivalent protein preparations derived from uninduced leaves exhibited negligible rates of fructan synthesis. Feeding cycloheximide to leaves prevented fructan synthesis both by the tissue and by protein extracts. Cycloheximide did not directly inhibit in vitro fructan synthesis, suggesting that its in vivo effect was at the translational level. The characteristics of the in vitro reaction are compared with the properties of in vivo fructan synthesis and are discussed with respect to its possible physiological relevance.
Hyphal transport of15N‐labelled nitrogen by a vesicular—arbuscular mycorrhizal fungus and its effect on depletion of inorganic soil N
Authors: JOHANSEN A. , JAKOBSEN I. , JENSEN E. S. 
Published: April 2006

SUMMARYHyphal transport of nitrogen from a15N‐labelled ammonium source by a VA‐mycorrhizal fungus was studied under controlled experimental conditions.Cucumis sativusL. cv. Aminex (F1 hybrid) was grown alone or together withGlomus intraradicesSchenck and Smith in containers with a hyphal compartment separated from the rooting medium by a fine nylon mesh. Lateral movement of the applied15N towards the roots was minimized by using a nitrification inhibitor (N‐serve) and a hyphal buffer compartment. Recovery of15N by mycorrhizal and non‐mycorrhizal plants was 6 and 0%, respectively, after a labelling period of 23 days. The corresponding figures, without N‐serve added, were 4 and 7%. A prolongation of the labelling period by 8 days (N‐serve applied) resulted in an increase in the15N recovery by mycorrhizal plants to 30% of the applied15N. Non‐mycorrhizal plants contained only traces of15N. The external hyphae depleted the soil in the hyphal compartment efficiently for inorganic N. In contrast, hyphal compartments of control containers still contained considerable amounts of inorganic N. The15N assimilated by the external hyphae in one hyphal compartment was not translocated in significant amounts to the external hyphae in another hyphal compartment. The possible implication of this for inter‐plant N transfer by VA hyphal connections is discussed.
Dose—response relationships for SO2 fumigations in the lichens Evernia prunastri (L.) Ach. and Ramalina fraxinea (L.) Ach.
Authors: SANZ M. J. , GRIES C. , III NASH T. H. 
Published: April 2006

SUMMARYSulphur dioxide fumigation of the lichens Evernia prunastri (L.) Ach and Ramalina fraxinea (L.) Ach, whose thallus water content was held at 100‐120%, throughout each experiment, resulted in changes in net photosynthesis, dark respiration and chlorophyll content in relation to both concentration and duration of exposure. Net photosynthesis was the most sensitive response variable. Significant reduction in chlorophyll content was found when no recovery in net photosynthesis occurred after two weeks. A reduction in dark respiration was only found at high SO2 concentrations. Evernia prunastri was affected by lower concentrations and shorter exposure times than Ramalina fraxinea and the data for both species showed dose‐response relationships.
Deposition of H15NO3 vapour to white oak, red maple and loblolly pine foliage: experimental observations and a generalized model
Authors: HANSON PAUL J. , GARTEN CHARLES T. 
Published: April 2006

SUMMARYNitric acid vapour enriched with 15N (H15NO3) was volatilized into the cuvette of an open‐flow gas exchange system containing red maple (Acer rubrum L.), white oak (Quercus alba L.), or loblolly pine (Pinus taeda L.) seedling shoots to facilitate direct measurements of total foliar deposition, and subsequent assessments of the rate of HNO3 movement across the cuticle (transcuticular uptake). Total H15NO3 vapour deposition to foliar surfaces ranged from <5 to 27 nmol m‐2 s‐1 the variability being largely accounted for by differences in HNO3 concentrations and leaf conductance. Mean whole‐leaf conductance to HNO3 ranged between 0.9 and 3.4 mm s‐1 for hardwoods and between 6 and 34 mm s‐1 for loblolly pine. Of the total H15NO3 vapour deposited to leaves, an average of 39 to 48 % was immediately‘bound’into hardwood foliage whereas only 3 % was bound to loblolly pine needles. This implies that rain events might extract greater amounts of HNO3‐derived nitrate in throughfall from conifer canopies as compared to hardwood canopies. Post‐exposure H15NO3 uptake rates across the leaf cuticle increased with surface nitrate concentrations, but were 1 to 2 orders of magnitude lower (O06 to 0.24 nmol m‐2 s‐1) than total HNO3, deposition during exposures.A generalized leaf‐level model of HNO3 deposition to foliage capable of simulating deposition pathways to sorption sites on the leaf surface, and to the metabolically active leaf interior via transcuticular or stomatal pathways is formulated and suggested for use in planning future work on HNO3 deposition.
Phragmites australis: Venturi‐ and humidity‐induced pressure flows enhance rhizome aeration and rhizosphere oxidation
Authors: ARMSTRONG JEAN , ARMSTRONG WILLIAM , BECKETT PETER M. 
Published: April 2006

SUMMARYA Venturi‐induced convection of gases through the Phragmites rhizome system is reported and the effects of this, and a humidity‐induced convection previously described, are quantified. The Venturi‐convection is driven by a pressure differential created by wind blowing across tall dead culms which sucks air into the underground system via culms snapped off close to ground level. The results demonstrate how wind, by increasing Venturi‐induced convection, and how radiant energy, by increasing humidity‐induced convection, raise the oxygen concentrations in the rhizome system, thereby causing much greater fluxes of oxygen into root and rhizosphere than are achieved if rhizome aeration is by diffusion alone. In laboratory experiments convective flow rates of as low as 0·7‐1·4 × 10−8 m3 s−1 (approx. 20‐40 mm min−1 in the rhizome) were sufficient to raise rhizome oxygen concentrations to 90% of atmospheric. The significance of this is discussed in connexion with pollution control by constructed wetlands, and photographic evidence is provided of the rhizosphere oxidizing activities in soil and anaerobic solution. A mathematical model is derived to help to evaluate the contributions of convection and diffusion in rhizome aeration, and to assess the likely effects of root and rhizosphere oxygen demands.
A relationship between plant growth and increasing VA mycorrhizal inoculum density
Authors: Clapperton M. Jill , Reid David M. 
Published: April 2006

SUMMARYThe relationship was examined between the density of vesicular‐arbuscular (VA) mycorrhizal inoculum and the growth of Phleum pratense L. and Agropyron trachycaulum (Link) Malte. The most probable number method (MPN) was used with combinations of host, VA mycorrhizal inoculum and a series of dilutions of field soil. There was a positive correlation between the proportion of field soil and the amount of mycorrhizal colonization. The numbers of tillers and leaves, shoot and root dry weights, and root:shoot ratios were negatively affected by increasing proportions of field soil inoculum. The addition of fertilizer alleviated the effects of increasing proportions of field soil on plant growth and reduced the amount of colonisation by mycorrhizal fungi. The relationship between increasing proportions of field soil and plant growth was not species‐specific. We conclude that there was an interaction between the inoculum density of VA mycorrhizal fungi and soil nutrient availability which affected plant growth.
Morphological and physiological properties of symbiotic cyanobacteria
Authors: VAGNOLI L. , MARGHERI M. C. , And G. ALLOTTA , MATERASSI R. 
Published: April 2006

SUMMARYThe main morphological and physiological characters of several symbiotic cyanobacterial strains, isolated from different plant—cyanobacteria associations (Anthoceros, Azolla, cycads and Gunnera) were investigated. All the strains showed heterocystous immotile filaments and motile hormogonia, typical of the genus Nostoc. In accordance with their symbiotic origin, all were found capable of photoheterotrophic growth. On the basis of the morphological and physiological properties and the phycobiliprotein content, the isolates from Azolla appeared very close to each other and quite distinct from the other cyanobionts. The latter showed many characteristics in common, such as marked tendency to produce hormogonia, synthesis of C‐phycoerythrin and rather small dimensions of the akinetes. With regard to the cycad cyanobionts, there was no correlation between the properties of the isolates and the host plants.
Effect of an antibiotic from Oscillatoria sp. on phytoplankters, higher plants and mice
Authors: Chauhan V. S. , Marwah J. B. , Bagchi S. N. 
Published: April 2006

SUMMARYWhen cultured with an axenic planktonic Oscillatoria sp., growth of some cyanobacteria and a green alga was suppressed owing to release of an algicidal metabolite (antibiotic). Growth inhibition was also detected on exposure to a cell‐free extract of Oscillatoria or to an ether extract. The ether extract abolished the photosystem (PS) II activity of Anacystis nidulans. Experimentation with a combination of photosynthetic electron acceptor‐donor systems indicated that the antibiotic also inhibited PS II in isolated chloroplasts, primarily interacting at a site before P680 on the electron transport chain. The cyanobacterial product also suppressed growth of some natural isolates of cyanobacteria and green algae in controlled conditions and decreased the population density of a green alga (phytoplankton) in nature. Growth of higher plants was also affected, though only when the Oscillatoria extract was applied to leaves. Experimental mice were unaffected by the antibiotic. Upon thin layer chromatography of the ether extract, two fractions with algicidal activity fluoresced under ultraviolet light. Long‐chain saturated fatty acids were the major components of the fractions. The suitability of the antibiotic in control of toxic algae is discussed.
Effects of osmotic stress (NaCl and polyethylene glycol) on nitrate uptake, translocation, storage and reduction in ryegrass (Lolium perenne L.)
Authors: OURRY ALAIN , MESLÉ SYLVIE , BOUCAUD JEAN 
Published: April 2006

SUMMARYIn order in investigate the effects of osmotic stress on metabolism of NO3− in Lolium perenne L. cv. Réveille, plants were exposed to NaCl or polyethylene glycol 6000 in the culture medium. Four‐week‐old plants were kept in the dark for 36 h in order to decrease nitrate reductase activity (NRA). Afterwards, they were placed in a greenhouse for 27 h under continuous illumination with a nutrient solution containing 1 mM 14NH415NO3. To induce osmotic stress, the solution was supplemented with either NaCl or PEG 6000 to give an osmotic potential of —0·335 MPa in the medium. Osmotic adjustment in PEG treated plants was strongly limited, because PEG could not be absorbed. Over 70% of the osmoregulation in NaCl treated plants resulted from chloride uptake. Compared to control plants, PEG 6000 treatment decreased absorption (by 40%) and reduction (by 60 %) of NO3− in the leaves, leading to NO3− storage in the vacuolar pool. In contrast, addition of NaCl in the medium did not significantly affect either uptake or reduction of NO3−. The proportion of NO3− translocated to the leaves was unaffected by osmotic stress and represented about 76% of consumed NO3−. Nitrate reductase activity, measured in vivo with exogenously supplied NO3−, was not significantly different between treatments. Compared to reduction of p15NO3− in control plants, it appeared that reduction of NO3− in leaves of PEG‐treated plants was not limited by enzyme activity or by the amount of reducing power. Availability of NO3− at the site of reduction therefore seems to be limiting when PEG 6000 is added to the medium.
Salt tolerance of the coastal salt marsh grass, Sporobolus virginicus (L.) kunth
Authors: MARCUM K. B. , MURDOCH C. L. 
Published: April 2006

summaryGrowth responses, leaf water and osmotic relations, and tissue ionic and organic solute contents of Sporobolus virginicus (L.) Kunth, grown under solution culture in salinities of up to 450 mM NaCl, were studied. Shoot growth was stimulated by intermediate salt levels, concurrent with both an accumulation of Na+ and Cl− in shoots and a slight increase in shoot succulence. Root growth was stimulated at salinities of up to 450 mM NaCl, Osmotic adjustment of shoots was predominantly due to Na+, Cl−, and soluble carbohydrate accumulation, though a slight reduction in shoot succulence may have played a minor role at high salinity. Shoot Na+ and Cl− accumulation was tightly controlled, not exceeding levels required for osmotic adjustment, due in part to ion secretion by leaf salt glands. Shoots were selective for K+ over Na+, maintaining fairly constant K+ concentrations with increasing salinity, resulting in relatively high K+/Na+ ratios at high salinity. Increasing NaCl stimulated the accumulation of K+ in roots, which may have acted as a reservoir of K+ for shoots at high salinity. Glycinebetaine, and to a lesser extent proline and trigonelline, accumulated in shoot tissues with increasing salinity, though trigonelline concentrations were insufficient to be osmotically significant. Accumulation was closely associated with increases in shoot sap osmolality. It is proposed that glycinebetaine may act as a compatible solute in S. virginicus, as levels were sufficiently high to effect total osmotic adjustment of the cytoplasm at high salinity.
Seasonal variation in the ecophysiology of Littorella uniflora (L.) Ascherson in acidic and eutrophic habitats
Authors: ROBE W. E. , Griffiths H. 
Published: April 2006

summaryThe ecophysiology of the submersed aquatic macrophyte, Littorella uniflora (L.) Ascherson, has been compared at acidic and eutrophic habitats in the Lake District. The physico‐chemical environment (bulk‐water and sediment‐interstitial‐water pH, CO2, O2, nutrient concentrations and PAR) have been related to seasonal photosynthesis (CAM activity, [CO2]1 and CO2 and PAR response characteristics) and leaf growth rate of adult plants and ramets. In general, the environment was more favourable for plant growth at Esthwaite Water (the eutrophic site) than at Red Tarn (acidic). Although bulk‐water pH was higher at Esthwaite, sediments were deeper and interstitial water CO2 concentrations greater. Concentrations of nitrate and ammonium, phosphorus and potassium were also higher. However, shading by phytoplankton blooms and epiphytes reduced PAR incident on Esthwaite plants. Photosynthetic characteristics and growth of L. uniflora followed the seasonal changes in PAR and temperature. However, Esthwaite L. uniflora showed greater CAM activity, and slightly higher [CO2]1 and photosynthetic capacity. Esthwaite plants also possessed more numerous, shorter leaves with greater chlorophyll and nitrogen content, and leaf growth rate and ramet production were greater than for Red Tarn plants, Esthwaite L. uniflora transplanted to Red Tarn showed higher rates of growth than native Esthwaite plants, while Red Tarn L. unifiora transplanted to Esthwaite performed poorly and retained the lower rate of ramet growth found in native Red Tarn plants. End of season productivity was greatest in Esthwaite to Red Tarn transplants and lowest in Red Tarn to Esthwaite transplants. The relationships between environmental conditions and plant performance at the two sites are discussed in the context of the disappearance of L. uniflora from acidic and eutrophic sites in N. Europe in recent years.
Structure of fructopolysaccharide (asparagosin) from roots of asparagus (Asparagus officinalis L.)
Authors: SHIOMI NORIO 
Published: April 2006

SUMMARYFructopolysaccharide (asparagosin, fructan) was prepared from an extract of asparagus roots by chromatography on carbon‐Celite, paper and Toyopearl HW‐40S (gel permeation). The asparagus fructopolysaccharide was a mixture of saccharides ranging from DP (degree of polymerization) 12 to 22 approximately. It yielded fructose and glucose by hydrolyzing with acid or yeast β‐fructofuranosidase. The ratio of fructose to glucose in the enzyme hydrolysate was 13:1 by HPLC analysis. Structural determinations were made by 13C‐NMR spectroscopy. Strong signals corresponding to carbon‐1 (C‐l), C‐2, C‐3, C‐4, C‐6 and C‐5 of fructose residues in the fructopolysaccharide were observed at δ61.08–61.77, 103.64–104.26, 77.42–78.08, 74.43–75.09, 62.71–63.00 and 81.74 respectively. These chemical shifts were similar to those of inulin. Moreover, weaker signals were also detected at δ92.85, 71.80, 73.13, 69.79 and 72.23 due to C‐l, C‐2, C‐3, C‐4 and C‐5 of the glucose residue. The chemical shifts are almost identical to those of glucose carbons in raffinose, neokestose, 6G(l‐β‐D‐fructofuranosyl)2sucrose and lF,6G‐di‐β‐D‐fructofuranosyl sucrose. These findings were confirmed by analysis of methanolysate from permethylated fructopolysaccharide by using gas‐liquid chromatography. The fructopolysaccharide from asparagus roots was composed of saccharides possessing approximately 11–21 fructose residues linked by β‐2,l bonds and a non‐terminal glucose residue bound with fructose residues at positions C‐l and C‐6.
The uptake of glucose, fructose and sucrose into pea powdery mildew (Erysiphe pisi DC) from the apoplast of pea leaves
Authors: AKED J. , HALL J. L. 
Published: April 2006

SUMMARYPatterns of sugar uptake into the mycelium of Erysiphe pisi DC have been investigated. Discs of mildewed pea (Pisum sativum L. cv. Onward) leaves were floated on radiolabelled sugar solutions. The mycelium was then removed and its total radioactive content was measured. The uptake from 1 mol m−3 fructose and 3‐O‐methylglucose (3‐OMG) was linear for at least 3 h, whereas the rate of uptake of glucose and sucrose increased with time. The uptake of glucose was markedly more rapid than that of the other three sugars, while 3‐OMG was the least well transported to the mycelium. Over a range of sugar concentrations, uptake of glucose and fructose was biphasic; however, whereas uptake of fructose showed a rapid linear increase over a higher concentration range (> 20 mol m −3), uptake of glucose and sucrose tended to plateau with sucrose hardly changing in rate of uptake at concentrations above 10 mol m−3. Increasing the pH of the uptake solution from 5 to 8 caused a slight but steady decrease in the uptake of glucose, fructose and sucrose. Decreasing the temperature from 25 to 4 °C decreased the uptake of all 3 sugars by 75–85 %. The effects of erythrosin B, parachloromercuribenzene sulphonic acid and carbonyl cyanide m‐chlorophenylhydrazone on sugar uptake were investigated. It appears that much of glucose uptake into the mycelium may be by facilitated diffusion driven by a concentration gradient. This gradient could be maintained by rapid metabolism of glucose in the fungal cytoplasm. It is concluded that there are probably carriers for all three sugars operating at lower concentrations (< 10 mol m −3).
Comparison of sulphite oxidation mechanisms in three lichen species
Authors: MISZALSKI ZBIGNIEW , NIEWIADOMSKA EWA 
Published: April 2006

SUMMARYThree species of lichen: Hypogymnia physodes (L.) Nyl., Pseudevernia furfuracea (L.) Zopf and Usnea filipendula Stirt. with differing sensitivities to SO2 were examined for differences in their ability to carry out sulphite oxidation. The factor responsible for sulphite oxidation is not connected with the metabolic activity of thalli and probably the oxidation does not take place in reaction with O2− The rate of sulphite oxidation may well depend on the content of heavy metals in the thalli.
Effects of phosphate and nitrogen application on death of the root cortex in spring wheat
Authors: ELLIOTT G. A. , ROBSON A. D. , ABBOTT L. K. 
Published: April 2006

SUMMARYProgrammed senescence and relative sink‐strength have both been proposed as mechanisms controlling cell death in the root cortex. To distinguish between the two, seedlings of spring wheat (Triticum aestivum L.) were grown for 23 d in a glasshouse, with five rates of phosphorus and three rates of nitrogen, and cortical cell death over the length of the first seminal root axis assessed after staining with acridine orange.The percentage of cortical cell death was greatest in plants moderately deficient in phosphorus and was less in plants receiving severely deficient or adequate‐to‐luxury supplies. Nitrogen supply did not affect the percentage of anucleate cells in the cortex. Both phosphorus and nitrogen supply influenced the distribution of cortical death with distance along the root except in regions close to the root tip. Nitrogen supply, however, had no effect on the extent of cortical cell death in regions of comparable age, except in plants receiving twice the level of phosphorus required for maximum plant growth.Phosphorus supply influenced the extent of cortical death through effects on both the ratio of root to shoot weight, and the length of the total root system. These findings cannot be completely explained by the process of natural programmed senescence, but are compatible with the theory that cortical cell death is related to the distribution or activity of assimilate sinks within the root.
Variation in the chromosome number of Parnassia palustris L. in the British Isles
Authors: GORNALL R. J. , WENTWORTH J. E. 
Published: April 2006

SUMMARYThe varieties of Parnassia palustris L. in the British Isles (var. palustris and var. condensata Travis & Wheldon) each have two cytodemes: a diploid (2n= 18) and a tetraploid (2n= 36). The distribution of the cytodemes is loosely correlated with the limits of the Devensian glaciation.