bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nutrient supply, nutrient demand and plant response to mycorrhizal infection
Authors: KOIDE ROGER T. 
Published: April 2006

summaryOne of the most dramatic effects of infection by vesicular‐arbuscular mycorrhizal fungi on the physiology of the host plant is an increase in phosphorus absorption. When phosphorus is limiting, the maximum extent to which mycorrhizal infection can improve plant performance is thus predicted to be a function of the phosphorus deficit of the plant, the difference between phosphorus demand and phosphorus supply. Phosphorus demand is defined as the rate of phosphorus absorption that would result in optimum performance of the plant as measured by growth rate, reproduction or fitness. The phosphorus supply is defined as the actual rate of phosphorus absorption under the prevailing conditions. Variation among plant taxa in morphological, physiological or phenological traits which affect either phosphorus demand or phosphorus supply (and thus phosphorus deficit) is predicted to lead to variation in potential response to mycorrhizal infection. The actual response to mycorrhizal infection is predicted to be a function of the increase in phosphorus uptake due to mycorrhizal infection and the phosphorus utilization efficiency of the plant. Demonstrated variability in responsiveness to mycorrhizal infection among plant taxa suggests that mycorrhizal fungi may play an important role in determining the structure of plant communities.Mycorrhizal infection may alter the phosphorus deficit or phosphorus utilization efficiency independently from its direct effect on phosphorus uptake, making the prediction of response to mycorrhizal infection based on the traits of non‐mycorrhizal plants quite difficult. For example, infection may at times increase the rate of phosphorus accumulation beyond that which can be currently utilized in growth, reducing the current phosphorus utilization efficiency. Such momentary ‘luxury consumption’ of phosphorus may, however, serve a storage function and be utilized subsequently, allowing mycorrhizal plants ultimately to outperform non‐mycorrhizal plants.

CONTENTS

Summary
365

I.
Introduction
366

II.
The concepts of phosphorus supply, phosphorus demand and phosphorus deficit
367

III.
Factors which affect phosphorus supply
369

IV.
Plant traits which affect phosphorus demand
370

V.
Variation in response to mycorrhizal infection
372

VI.
The effect of infection on inherent traits which influence phosphorus supply, phosphorus demand or phosphorus utilization efficiency
378

VII.
Mycorrhizal effects not related to phosphorus
380

VIII.
Conclusions
380

Acknowledgements
381

References
381
Selective interactions between different species of mycorrhizal fungi and Rhizobium meliloti strains, and their effects on growth, N2‐fixation (15N) and nutrition of Medicago sativa L.
Authors: AZCÓN R. , RUBIO R. , BAREA J. M. 
Published: April 2006

summaryThree isolates of vesicular‐arbuscular (VA) mycorrhizal fungi, belonging to the species Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, G. fasciculatum (Taxter sensu Gerd.) Gerd, and Trappe, and G. caledonium (Nicol. and Gerd.) Trappe and Gerd, were inoculated in dual combinations with six strains of Rhizobium meliloti with the aim of testing these combinations for functional compatibility with their common host plant, the legume Medicago sativa L. Symbiotic efficiency (promotion of plant growth and N and P nutrition) was found to be dependent on the particular combination of Rhizobium strain and Glomus species indicating selective and specific compatibilities between strains and isolates of the two types of microsymbiont, but also between them and the common host plant. Observed effects on plant growth were in general, though not always, related to the extent of VA mycorrhizal colonization. Although the different mycorrhizal and/or rhizobial treatments produced different effects on plant growth, the rate of nodule formation on M. sativa roots remained constant. Most mycorrhizal treatments increased the concentration and/or content of N in plant shoots but effectiveness was in the order: G. fasciculatum > G. mosseae > G. caledonium. In some cases, this increase in N‐content may be a consequence of a P‐mediated stimulation of N2‐fixation by VA mycorrhiza, as ascertained using 15N. In other instances, however, the increase seems to reflect a VA mycorrhizal‐mediated enhancement of N‐uptake from soil. VA mycorrhizal inoculation decreased the concentration of Ca and Mg in plant shoots and a buffering effect of VA mycorrhiza in situations of nutrient excess in soil is proposed.
Carbohydrate transport in discs of storage parenchyma of celery petioles
Authors: DIETTRICH BEATE , KELLER FELIX 
Published: April 2006

summaryPetioles of celery leaves function successively as net importing (sink) and net exporting (source) organs during ontogeny. The parenchyma of these petioles is the main store for large amounts of D‐glucose, D‐fructose and mannitol. The mechanism of uptake of glucose and fructose into discs isolated from storage parenchyma of celery petioles was investigated. Uptake kinetics showed a biphasic response to increasing concentrations for both hexoses with a saturable component at low concentrations and a non‐saturable, linear, diffusion‐like component at higher concentrations (at least up to 16 mM). The apparent Kns‐values were an order of magnitude higher for fructose (2–3 mM) than for glucose (034 RIM) uptake. The saturable components of uptake of the two hexoses were inhibited similarly by the SH‐reagents PCMBS and NEM, the uncouplers CCCP and DNP, the ATPase inhibitor DES and the hydrophobic reagents phloretin and phlorizin. They were stimulated by the plasmalemma H+‐ATPase stimulator FC and showed a broad pH‐optimum around pH 6. Competition studies revealed that glucose uptake was very specific whereas fructose uptake was inhibited by D‐glucose, L‐sorbose and D‐tagatose. The saturable components of uptake of both hexoses were clearly turgor‐dependent. Lowering of cell turgor resulted in a linear increase of Vmax and a constant Km.It is concluded that the saturable components of glucose and fructose uptake are of a similar, active, sugar‐proton cotransport type with carriers containing SH‐groups and interacting hydrophobically. It is suggested that two different hexose carriers might be operative, one for glucose only and one for both glucose and fructose.
Carbohydrate transport in discs of storage parenchyma of celery petioles
Authors: KELLER FELIX 
Published: April 2006

summaryThe sugar alcohol mannitol is, together with glucose and fructose, the main soluble carbohydrate of celery petioles. It is accumulated in the storage parenchyma of mature petioles and remobilized during senescence. The mechanisms of mannitol uptake into discs isolated from petiole parenchyma was studied. Uptake kinetics showed a biphasic response to increasing external concentrations of [14C]D‐mannitol with a predominant saturable component at low concentrations (below about 2 mM) and a linear component at higher concentrations (at least up to 16 mM). The saturable component showed an apparent Km of about 1 mM and a fairly sharp pH optimum around pH 6–5. It was stimulated by the plasmalemma H+‐ATPase stimulator FC and inhibited by the SH‐reagents PCMBS and NEM and the uncoupler DNP. CCCP was also inhibitory, but its effect could be reversed by DTT, suggesting a dual role of CCCP as SH‐reagent and uncoupler in this tissue. Competition studies with 14‐different polyols and sugars showed that uptake was very specific. The saturable uptake component was clearly turgor‐dependent. Lowering of cell turgor by treatment of increasing concentrations of the relatively nonpermeant glycinebetaine (0 to 0.8 M) resulted in a linear increase of Vmax and an unaltered Km.It is concluded that celery petiole parenchyma contains at least a mannitol carrier at the plasmalemma which operates in an active proton‐cotransport manner. It is speculated that a superimposed mannitol carrier is present at the tonoplast and might operate by facilitated diffusion.
Effect of some triazole fungicides on intracellular pH and on cell membrane permeability in leaves of Elodea densa (Planch.) Casp.*
Authors: ROMANI G. , BEFFAGNA N. 
Published: April 2006

summaryRecent data obtained in this laboratory have shown that a number of triazole fungicides induce in leaves of barley and Elodea densa an early release of solutes and an inhibition of H+ extrusion. This paper deals with the early effects of two triazoles, penconazole and flusilazol, on intracellular pH and plasmamembrane permeability in Elodea densa leaves.Different effects were found at low (0.1–0.15 mM) or at high (0.3–0.5 mM) triazole concentrations. At the low concentrations the triazoles induced a marked intracellular acidification (corresponding to an acidification of both the cytosol and the vacuole) as evaluated by the weak acid and weak base distribution method. For higher triazole concentrations (0.3–0.5 mM) the intracellular pH became very close to that of the external medium (pH 5.5), and cytosolic and vacuolar pH measurements became unreliable. Triazoles at concentrations higher than 0.1–0.15 mM induced an early and very marked increase in net efflux of K+ and Cl−. At these ‘toxic’ concentrations the sorbitol‐permeable space (apparent free space) was increased from about 20% to more than 90%. These results suggest that triazoles at low ‘sub‐toxic’ concentrations inhibit some mechanism involved in the regulation of intracellular pH (possibly the plasmalemma proton pump), whilst at higher concentrations they induce a non‐specific increase in passive permeability of the plasmamembrane.
Arsenic, cobalt and nickel tolerances in two populations of Silene vulgaris (Moench) Garcke from Ontario, Canada
Authors: PALIOURIS GEORGIA , HUTCHINSON THOMAS C. 
Published: April 2006

summaryA population of Silene vulgaris (Moench) Garcke collected from mine tailings near the town of Cobalt, Ontario was compared in its metal tolerance with a population collected at an uncontaminated site (Baymouth, Ontario). Seedlings of the Cobalt population were tolerant to elevated levels of arsenic, cobalt and nickel, both compared with the Baymouth population and with other literature reports for this species. However, the tolerance indices in the Cobalt plants for these toxic elements did not correlate well with their concentration in water extractions in the mine soils.Indices of arsenic tolerance, based on the inhibition of root growth in 12 d experiments, showed a similar response to that in a 28 d experiment for both populations. The latter however, appeared to be a more accurate indicator of As tolerance in S. vulgaris, because the longer‐term tolerance indices had lower standard deviations and higher probabilities for tolerance than the short‐term tolerance indices. Reduced uptake of As occurred in the roots of tolerant individuals compared with non‐tolerant individuals at a low As treatment. At a higher arsenic exposure, however, arsenic entered the roots of tolerant individuals. A partial exclusion or reduced translocation of arsenic to the shoots then appeared to operate in the shoots of tolerant individuals, i.e. arsenic levels were higher in shoots of non‐tolerant plants. At the highest arsenic exposure, where the individuals from the Cobalt population were no longer tolerant, this exclusion pattern broke down. From a preliminary selection experiment, some arsenic tolerant individuals occurred in the Baymouth population. This suggests that under circumstances of arsenic contamination this population also has the potential to develop a tolerance to high arsenic exposure.
Responses of growth, photosynthesis, and leaf conductance to white light irradiance and end‐of‐day red and far‐red pulses in Fuchsia magellanica Lam.
Authors: APHALO P.J. , GIBSON D. , Di BENEDETTO A. H. 
Published: April 2006

summaryThe response of Fuchsia magellanica Lam. – a shade‐tolerant perennial – to white light photon flux density and end‐of‐day red and far‐red light irradiation was studied to evaluate the role that different morphological and functional alterations play in whole‐plant acclimation to shade. The estimated relative growth rate of plants growing under a photon flux density of 30μmol m2 s1 was 71 % of that of those growing under 450μmol m−2 s−1. The proportion of total dry weight allocated to shoots was higher in low light plants, but the proportion of shoot dry weight allocated to leaf blades was not affected by any of the treatments. The estimated relative growth rate, specific leaf area and leaf conductance were not affected by end‐of‐day irradiation. In low light plants the specific leaf area was higher, and at saturating photon flux density photosynthesis was lower on a leaf area basis, but was not on a leaf dry weight basis. Dark respiration was higher in high light plants when expressed on an area basis, but not when expressed on a dry weight basis. During the normal photoperiod, leaf conductance measured in darkness was higher in high light plants than in low light ones, which is consistent with the higher stomatal density observed in these plants. The cross‐sectional area of the petioles was slightly reduced in low light in spite of a large increase in the area of individual leaves. Low irradiance affected the display of leaves, decreased leaf thickness and increased chlorophyll content per unit dry weight. End‐of‐day far‐red resulted in plants with more erect branches. Both low photon flux density and far‐red enhanced internode elongation. The effect of end‐of‐day irradiations was bigger in low light than in high light, which is the opposite to what is observed in shade‐avoiders. The relatively small difference in mean growth rate can be explained by changes in specific leaf area, shoot: root dry weight partition ratio, and by the shape of the photosynthetic light response curve. However when comparing photosynthetic rates on a dry weight basis low light plants do not seem to be at a disadvantage under high light.
Relationship of nutrients in water with biomass and nutrient accumulation of submerged macrophytes of a tropical wetland
Authors: SHARDENDU  , AMBASHT R. S. 
Published: April 2006

summaryThe paper describes monthly biomass, seasonal and annual net primary productivity and monthly and seasonal nutrient content of four submerged macrophytes in a lentic wetland situated in the campus of Banaras Hindu University. The seasonal variation of six nutrients (NO3 ‐N, PO4‐P, K, Ca, Mg, Na) in water is described and their mean concentrations used in multiple regression equations to examine the relationship between nutrients in water, plant biomass and nutrient accumulation in plant body. Hydrilla verticillata (L.f.) Royle, Potamogeton crispus L., P. pectinatus L. and Aponogeton natans (L.) Engle and Krause are the constituent species. Plants show rapid growth in post‐monsoon and pre‐winter months. All the four species showed biomass accumulation in the rainy season. The highest rate of production in the submerged zone was 0.73 g m−2 d−1 and the minimum was 0.29 g m−2 d−1. Maximum annual production of any species was 69 g m−2 in P. pectinatus. In all the four species the nutrient concentration decreased in the following order: calcium > nitrogen > potassium > magnesium > sodium > phosphorus. Seasonal variation of nutrient content was dependent on the period of germination, growth and development of the species. Nitrogen, phosphorus and potassium were higher in the season of growth of particular species and calcium was higher when plants matured. There was no definite trend for sodium, though magnesium varied with species. Uptake and accumulation of nutrients in submerged plants largely depend upon nutrient concentration of water, except nitrogen which was also dependent on biomas change. Sources of nutrient for plants are both sediment and water. Translocation of potassium from the overlying water to the mud by Hydrilla plants is possible as there is reduction in potassium concentration of water around Hydrilla.
Architectural analysis of plant root systems 2. Influence of nutrient supply on architecture in contrasting plant species
Authors: FITTER A. H. , STICKLAND T. R. 
Published: April 2006

summaryTwo components of root architecture (topology and link lengths) were measured in a group of 13 dicotyledon and eight grass species, under both high and low nutrient supply rates. Predictions were made, based on a simulation analysis, that root systems from plants grown in low nutrient conditions and those from plants characteristic of such conditions should have the more herringbone topology (branching principally on main axis) and longer links. Both these predictions were confirmed for the dicots, but data from grasses agreed with the predictions only in terms of geometry (link lengths) and not topology. The ecological character of the species was assessed on the assumption that species of low inherent relative growth rate were characteristic of infertile soils, Taxonomic patterns were also evident, indicating that some variation in root system architecture may be historical rather than adaptive.
Relationship between root cortical senescence and growth of wheat as influenced by mineral nutrition, Idriella bolleyi (Sprague) von Arx and pruning of leaves
Authors: LASCARIS D. , DEACON J. W. 
Published: April 2006

summarySevere deficiencies of nitrogen or calcium enhanced the rate of root cortical death (RCD) when wheat seedlings were grown in perlite in a glasshouse; less severe deficiencies had no effect on RCD even though they significantly reduced both root and shoot growth. Heavy pruning of leaves curtailed root growth but did not affect the rate of RCD in the presence or absence of the weakly pathogenic fungus, Idriella bolleyt (Sprague) von Arx. The results suggest that RCD is less responsive to environmental manipulations than is seedling growth, so RCD is unlikely to be part of a stress‐response mechanism in cereals whereby assimilates or mineral nutrients are mobilized or remobilized to growing tissues.
Effects of air pollution and water stress on leaf blight and twig cankers of London planes [Platanus×acerifolia (Ait.) Willd.] caused by Apiognomonia veneta (Sacc. & Speg.) Höhn.
Authors: VON SURY ROMAN , FLÜCKIGER WALTER 
Published: April 2006

summaryPotted 2‐year‐old cuttings of London plane trees [Platanus×acerifolia (Ait.) Willd.] were raised under well‐watered (WW) or water stress (WS) conditions in two semi‐open‐top chambers and fumigated with ambient air (AA) and filtered air (FA). In the FA chamber, charcoal and Reox‐Purafil† filters removed 65–100% of O3, 50–90% of NOx, and 80–95 % of SO2.After leaf inoculations in spring with conidia of Apiognomonia veneta (Sacc. & Speg.) Höhn., significantly fewer and smaller lesions appeared on AA than on FA trees. The WS treatment led to an additional, highly significant suppression of leaf blight. In winter, WW trees inoculated with mycelium of A. veneta developed significantly larger cankers in the AA than in the FA chamber. Under WS conditions, canker formation was somewhat reduced in AA and was similar in both chambers. The production of Apiognomonia conidia on necrotic bark in spring, however, was stimulated by the WS treatment, whereas no differences in conidiation were found between AA and FA. Germination and growth of A. veneta in vitro were both significantly suppressed in the AA chamber compared with the FA. In the laboratory, 50 nl O3/l significantly reduced the germination of A. veneta but the addition of an equal concentration of NO2 (up to 100 nl/l) had no effect. After one year of exposure, initial shoot growth of WW London planes was significantly inhibited under AA conditions and a delay of bud burst was also observed. It is concluded that the longer duration of tree dormancy in AA positively affected the development of Apiognomonia cankers.We suggest that ambient air pollutants suppressed leaf blight through a direct effect on the germinating conidia of A. veneta but that the enhancement of twig canker formation was rather due to effects on the host tree.
Short term effects of bisulphite on pollution‐tolerant and pollution sensitive populations of Sphagnum cuspidatum Ehrh. (ex. Hoffm.)
Authors: BAXTER R. , EMES M. J. , LEE J. A. 
Published: April 2006

summaryMoss tissue from two distinct populations of Sphagnum cuspidatum from N, Wales (‘unpolluted’) and the S. Pennines (‘polluted’) was exposed to 0.2 mM HSO3− over a 24–26 h period. The rates of HSO2−, disappearance in the bathing solution were monitored in conjunction with tissue dark respiration, net photosynthetic rate and chlorophyll a fluorescence induction kinetics. Slow disappearance of HSO3− in the presence of moss tissue from N. Wales (40% of initial concentration remaining after 24 h) resulted in a rapid (< 2 h) loss of photosynthetic oxygen evolution, and a gradual marked decline in tissue dark respiration and chlorophyll fluorescence quenching. In the S. Pennine tissue, rapid HSO3− disappearance in the growth medium (complete after < 4 h) resulted in a marked recovery of photosynthetic and respiratory pathways after the initial inhibitory effects of HSO3− on these processes. Pretreating S. Pennine moss tissue with EDTA prior to exposure increased HSO3− residence time with consequent rapid decline in net photosynthetic rate, rendering the response of the moss similar to that from N. Wales (‘unpolluted’ site).In a second experiment, identical moss samples from the two study sites were exposed to 0.2 mM HSO3− for a period of 24 d. One set of plants from each population was prewashed in 5mM EDTA to remove extracellularly‐bound cations prior to HSO3− exposure. Growth decrease was greater in the unpretreated moss N. Wales (74% with respect to tissue not exposed to HSO3−) than that from the S. Pennines (45.5%). After 10 days the pigments of the former were visibly bleached. No bleaching was observed in the latter.In the moss from N. Wales, removal of the extracellular cations with EDTA only slightly enhanced the effect of HSO3− on growth, whilst in the S. Pennine plants EDTA pretreatment resulted in a further growth reduction of 13%.The differential response of the moss from the two sites is discussed as a function of the extracellular transition metal concentration (Notably Fe) associated with the plants.
Seasonal variations in acidic pollutant inputs and their effects on the chemistry of stemflow, bark and epiphyte tissues in three oak* woodlands in N.W. Britain
Authors: FARMER A. M. , BATES J. W. , BELL J. N. B. 
Published: April 2006

summaryRainfall, throughfall and stemflow chemistry, bark chemistry and gaseous air pollutant levels were monitored for one year within three Quercus petraea (Mattuschka) Liebl. woodlands in north west Britain. Tissue chemistry of the epiphytic lichen Lobaria pulmonaria (L.) Hoffm. and the moss Isothecium myosuroides Brid. were also studied at the sites in which they were abundant. The sites were found to differ in the levels of acidic and nutrient inputs, bark chemistry and levels of gaseous pollutants, although the latter were low at all the sites. The epiphyte tissue chemistry responded to changes in stemflow chemistry across the season. At Borrowdale, Cumbria, where acid sensitive lichens have declined, stemflow was always of a low pH (3.5–4.5) and low nutrient content. The tissues of I. myosuroides at this site had low concentrations of nutrient cations, but a high nitrogen content, possibly due to a high nitrate input in the rainfall. It is concluded that acid precipitation will affect epiphytes by reducing the bark's buffering capacity and increasing its acidity. The extent to which this occurs will depend on tree species, soil chemistry and the nature of the atmospheric inputs. This is discussed in the context of the concept of critical loads for acidifying deposition.