bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and ultrastructural disorders in cadmium‐treated bush bean plants (Phaseolus vulgaris L.)
Authors: BARCELÓ J. , VÁZQUEZ M. D. , POSCHENRIEDER Ch. 
Published: April 2006

summaryThe effect of a growth reducing cadmium concentration (5 μg ml−1) on the structure and ultrastructure of leaves, stomata and plastids of bush bean plants (Phaseolus vulgaris L. cv. Contender) grown on perlite was studied using light, transmission electron and scanning electron microscopy. The structural and ultrastructural alterations observed were not directly related to the average Cd content of the whole organs. In roots, where the highest Cd concentration was found, plastid ultrastructure was hardly affected, while in the upper parts of the plant the chloroplasts showed severe alterations. Disruption of chlorophyll synthesis and plastid ultrastructure was greater in young trifoliate leaves than in primary leaves. The effects of Cd toxicity on the structure and ultrastructure and their physiological implications are discussed in relation to Cd uptake.
Iron‐deficiency specifically limits nodule development in peanut inoculated with Bradyrhizobium sp.
Authors: O'HARA G. W. , DILWORTH M. J. , BOONKERD N. , PARKPIAN P. 
Published: April 2006

summarySeverely iron‐deficient peanuts (Arachis hypogaaea L.) grown on calcareous soils in central Thailand failed to nodulate until given foliar iron applications. Glasshouse experiments were conducted on two cultivars (Tainan 9 and Robut 33–1) to identify which stage of the nodule symbiosis was most sensitive to iron‐deficiency.Iron‐deficiency did not limit growth of soil or rhizosphere populations of peanut liradyrhizobium. Similar numbers of root nodule initials formed in the roots of both control and iron‐sprayed plants, showing that iron‐deficiency did not directly affect root infection and nodule initiation. Plants sprayed with iron produced greater numbers of excisable nodules and carried a greater nodule mass than untreated plants. Five days after iron application, nodules on sprayed plants of CV. Tainan 9 contained 200–fold higher bacteroid numbers per unit weight and 14–fold higher concentrations of leghaemoglobain. The onset of nitrogenase activity was also delayed by iron deficiency in both cultivars. Tainan 9 appeared more sensitive to iron‐deficiency than Robut 33‐1 in terms of nodule mass produced, but both cultivars showed the same effect of iron‐deficiency on nitrogenase activity per plant.It is concluded that the failure of the infecting rhizobia to obtain adequate amounts of iron from the plant results in arrested nodule development and a failure of nitrogen fixation.
Growth and phosphorus inflows of Trifolium repens L. with a range of indigenous vesicular‐arbuscular mycorrhizal infection levels under field conditions
Authors: McGonigle T. P. , Fitter A. H. 
Published: April 2006

summarySince vesicular‐arbuscular mycorrhizas (VAM) are believed to play a fundamental role in phosphorus (P) uptake for many plant species, an experiment was performed to test the hypothesis that rates of P uptake per unit root length (P inflow) should be proportional to the extent of infection. Plants of Trifolium repens L. were grown in pots containing different proportions of sterile and non‐sterile soil in radially arranged rooting compartments and transplanted with a consequent range of mycorrhizal infection into the field at a hay meadow of moderate P fertility. Even though plant growth in the field was exponential, plants with greater proportions of their root systems infected did not have higher P inflows or dry matter production. For much of the experiment P inflows were below the levels at which it would be necessary to invoke mycorrhizally assisted uptake. It is suggested that for Trifolium repens, even while the plant is growing actively in the field, VAM do not always function mutualistically.
Effects of sulphur dioxide and acid rain alone or in combination on growth and yield of broad bean plants
Authors: ADAROS G. , WEIGEL H. J. , JÄUGER H.‐J. 
Published: April 2006

summaryPotted plants of Vicia faba L. cv. ‘Con Amore', grown either in soil or quartz gravel were exposed in eight open‐top chambers to two levels of SO2 (charcoal‐filtered air and charcoal‐filtered air enriched with SO2) and two artificial rain treatments (pH 5.6 and pH 3.0/4.0), alone or in combination. SO2 was dosed continuously (55–90 μg m−3 for 56 days) and rain solutions were applied on three days each week for 8–9 min each day resulting in 4.45 mm rainfall per week and a total H+ deposition of 0.15 kg ha−1 and a total water deposition of 37 mm. Variables measured at different stages of plant development included fresh and dry weight of whole plants, leaves, stalks, fruits and roots; number of leaves, stalks, blossoms, pods and seeds; leaf area; plant height; sulphur content. While the sulphur content of the leaves of all plants significantly increased due to the SO2 fumigation, the effect on the growth of young plants depended on the root medium; plants grown in soil were mainly influenced in a positive manner (increase of fresh and dry weight; number of leaves, blossoms and pods), whereas plants grown in quartz gravel were negatively affected. At maturity these tendencies were only observed in marketable products like seeds (plants grown in soil) or pods (plants grown in quartz gravel). The acid‐rain treatment resulted in a decrease of total fresh and dry weight and fruit production of plants grown in soil, while, particularly at the beginning of the rain treatments, dry weight of whole plants and leaves as well as the number of leaves of plants grown in quartz gravel decreased. Some interactions between the two pollutants, which were mostly negative in nature, were also observed.
Phenols and bud dormancy I. Variations in total phenols and phenylalanine ammonia lyase activity in dormant buds of Fagus sylvatica L.
Authors: CODIGNOLA ARNALDO , MAFFEI MASSIMO , FIESCHI MAURIZIO 
Published: April 2006

summaryQuantitative analyses of the total phenols (glucosides and aglycones and phenylalanine ammonia lyase (PAL) activity were determined separately in bud scales and the leaf primordia of dormant buds (apical, subapical and basal) of Fagus sylvatica L, until bud burst.In all the leaf primordia, the phenol and glucoside contents did not change substantially from November to March. From dormancy break to bud burst, phenols and glucosides accumulated in the subapical and basal buds. PAL activity, after a drop at the inception of dormancy, followed a trend similar to that of the total phenol content during dormancy. After dormancy break, the PAL activity of the apical bud was higher than that of the subapical and basal buds. During this period several differences were observed between PAL activity and phenolic content along the branch. No aglyeortes were detected during dormancy (except small quantities in the subapical buds). However, small amounts were detected in all three bud types after dormancy break.On the other hand, in the bud scales during the winter total phenols per bud, glucosides and PAL activity values (except in the apical buds) show a slight decrease. After dormancy break, PAL activity disappeared and aglycone levels increased slightly. At the same time it was not possible to determine any clear net variation in the levels of phenols and glucosides.It seems, therefore, that the inception and maintenance of dormancy in F. sylvatica buds buds cannot be correlated to the total phenolic pool and PAL activity in leaf primordia, while some kind of correlation seems to occur in the case of bud scales.
Pollen wall development in Olea europaea L.
Authors: FERNÁNDEZ M. C. , RODRÍGUEZ‐GARCÍA M. I. 
Published: April 2006

summaryThe ontogeny of the olive pollen grain (Olea europaea L.) wall is related to the structural changes which take place during the various stages of pollen grain development. The tetrad stage sees the deposition of the primexine, with probacules forming by deposition of material adjacent to the plasmalemma. Endexine development commences subsequently. The bacules and foot‐layer are formed mainly from dense material found within the special callose wall. By the young free microspore stage the definitive structure of the exine has been determined. Throughout development microchannel‐like structures are present in both bacules and the foot‐layer. An electron‐lucent zone appears between the plasmalemma and the endexine. This is the future site of intine deposition which occurs during the vacuolated microspore stage before postmeiotic mitosis. A fibrillar layer lines the arcade spaces of the exine. Between this stratum and the exine lies a thin layer of polysaccharides probably representing the remains of the primexine or glycocalyx. In the mature pollen grain the exine arcades contain numerous lipid drops (or pollenkitt), originating from the degenerating tapetum.
Dinoflagellates, their cysts and Quaternary stratigraphy
Authors: HARLAND REX 
Published: April 2006

summaryDinoflagellates are described, with particular emphasis on their feeding strategies and role within the phytoplankton. The potential ecological value of the fossilizable hypnozygotic cyst in reconstructing the climate throughout the Quaternary marine record is noted. Dinoflagellate cysts can be used to detect changing climates in marine Quaternary sediment sequences as pollen is used for continental Strata. The unique capacity of dinoflagellate cysts in effecting correlations from the deep ocean to the inner shelf is of potential importance.
Acquisition of nitrogen by the shoots of land plants: its occurrence and implications for acid‐base regulation
Authors: RAVEN J. A. 
Published: April 2006

summaryThe typical N source for terrestial vascular plants is the soil in which they are rooted. N exchange between the aerial shoot and its environment, as gaseous, dissolved or particulate N, can involve either net loss or net gain of N by the plant. Net gain of N by the plant shoot at the expense of its aerial environment can be significant, under natural or agricultural conditions, for all three forms of aerial N (NH3,N2,NO3), Gaseous N gain can be substantial, as NH3, for plants growing on soils receiving large inputs of animal excreta and faeces. Soluble N uptake by shoots is the major N source for ‘atmospheric’ epiphytes. Particulate N supply to shoots is a major N source for carnivorous plants. Experimentally, several plants which normally grow with N supply mainly via their roots can be grown with a predominant, or sole, supply via their shoots.Plant growth with CO2, as C source, SO42−as S source and H2PO4, as P source generates excess OH (∼ 0.78 OH−/N assimilated) in the synthesis of core metabolites when the N source is NO3−supplied to roots or shoots. All other N sources (except dicarboxylic amino‐acids) yield excess H+during synthesis of core metabolites. NH4+(in solution) supplied to roots or shoots yields some 1.22 H+/N assimilated, while NH3, N2or NO2supplied to shoots as gases, dissolved urea supplied to shoots or roots, and animal protein supplied to shoots of carnivorous plants, yields some 0.22 H+/N assimilated.These biochemically caused acid‐base perturbations may be exacerbated (NO2) or partially or, occasionally, completely offset (NH3) by effects related to solution and dissociation of the gas in growing shoots.Assimilation of the shoot‐acquired N in the shoots leads to somewhat different constraints on acid‐base homoiostasis relative to those found with assimilation of root‐acquired N. The shoot cannot generally excrete excess H+or OH−to its environment (as is so for root‐assimilation of N), nor can it dispose of H+biochemically without co‐operation of root metabolism and root–shoot and root‐rhizosphere transport processes. Excess OH−from shoot‐acquired and shoot‐assimilated NO3−can, by contrast, be disposed of biochemically after the fashion of root‐acquired, shoot‐assimilated NO3−. Tentative conclusions as to the disposal of excess H+generated in shoot acquisition and assimilation of N‐sources other than NO3−and NO2−are different for rhizophytes and for haptophytes. Rhizophytes probably carry out a net synthesis of organic acid in the roots, with subsequent cation‐H+exchange at the root plasmalemma, transport of cation salt of the organic acid to the shoot in the xylem, and metabolism of the organic acid anion in the shoot to yield OH−. Haptophytes probably have an excess of liquid water supply over their needs for growth and transpiration due to the very low N concentration in this water; they thus have the potential for H+(as strong acid) excretion to the excess surface water which is lost, at least in part, as liquid water.
Dry matter, phosphorus and nitrogen partitioning in three Eucalyptus species grown under a nutrient deficit
Authors: MULLIGAN D. R. , SANDS R. 
Published: April 2006

summarySeedlings of Eucalyptus grandis Hill ex Maiden, E. gummefera (Sol. ex Gaertner) Hochr. and two provenances of E. pilularis Smith [Coffs Harbour (CH) and Myall Lakes (ML)] were grown for 21 weeks in sand culture under nutrient‐limiting conditions. Over this period the seedlots originating in the more phosphorus‐deficient sites, E. gummifera and E. pilularis (ML), produced a larger mass and extracted 2–5 times more phosphorus (but 60–70% less nitrogen) from the sand than did the representatives from fertile habitats, E. grandis and E. pilularis (CH). Large seed reserves of phosphorus were a contributing factor to the success of E. gummifera and in both species adapted to low phosphorus, the early establishment of a larger root system conferred an advantage. E. grandis and E. pilularis (CH) had lower tissue phosphorus concentrations (approx. 160 μg g−1) and hence by definition would be considered more efficient utilizers of phosphorus. However, this ‘efficiency’ was the result of an internal partitioning strategy that permitted growth to proceed unchecked and phosphorus dilution to continue. Under the severe limitations to phosphorus supply of this experiment, the more effective strategy was that adopted by E. pilularis (ML) and E. gummifera. These species developed a storage or buffer strategy which would allow longer‐term survival by ensuring critically low phosphorus concentrations were not reached. The difficulties of the less tolerant E. grandis and E. pilularis (CH) were compounded by a disproportionate amount of nitrogen uptake which created an ion imbalance in the tissues.
Characterization of sucrose: sucrose fructosyltransferase from crested wheatgrass*
Authors: CHATTERTON N. J. , HARRISON P. A. , THORNLEY W. R. , BENNETT J. H. 
Published: April 2006

summaryBiosynthesis of the trisaccharide precursor of fructan occurs through the action of sucrose: sucrose fructosyltransferase (SST). This study defines the optimal conditions for in vitro SST and invertase activities from a crested wheatgrass hybrid developed from a cross between Agropyron cristatum (L.) Gaertn. ×A. desertorum (Fisch. ex Link) Schult. Enzyme extracts were prepared from field‐grown plants. The optimum pH for SST and invertase activities were 5.0 and 4.5, respectively. The effective Km for SST (100 mol m−3) is much larger than invertase (15 mol m−3). Sodium pyrophosphate differentially reduced invertase activity without affecting SST activity. Conversely, CaCl2 and CsCl reduced SST activity without altering invertase activity. Optimal in vitro reaction temperatures for SST and invertase were 30 and 50°C, respectively. SST activity was 30% of maximum at temperatures as cool as 5°C. In contrast, invertase activity was only 10% of maximum at 15 °C. The responses of SST and invertase to changes in pH, temperature, and additives provide additional evidence that the two activities are the result of two distinct enzymes. It is hypothesized that cool‐season grasses such as crested wheatgrass have the ability to fix carbon photosynthetically at lower temperatures than starch‐accumulating species because of their capacity to synthesize fructans.
Blue light effects on the growth ofLolium multiflorumLam. leaves under natural radiation
Authors: CASAL J. J. , ALVAREZ M. A. 
Published: April 2006

summaryPlants ofLolium multiflorumLam. were grown under natural radiation supplemented with blue light during the photoperiod. The blue light treatment reduced final length of the leaf sheath but did not modify lamina length compared with control non‐irradiated plants. Leaf sheath length was linearly and inversely related to the log‐fluence rate of supplementary blue light. The rate of leaf elongation was unaffected until the target leaf reached 35–70% of its final length. Red light had no effect at fluence rates that were inhibitory in the case of blue light and promoted leaf growth at high fluence rates. Plants grown under natural canopies also responded to supplementary blue light. Fully de‐etiolatedL. multiflorumplants respond to different fluence rates of blue light within a range found in natural canopies. The possible photoreceptor and ecological implications are discussed.
Bicarbonate utilization by the marine diatomPhaeodactylum tricornutumBohlin
Authors: DIXON G. K. , MERRETT M. J. 
Published: April 2006

summaryThe measurement of inorganic carbon dependent photosynthetic oxygen evolution in air‐grown cells ofPhaeodactylum tricornulumBohlin has shown that sodium ions increased the affinity of the cells for bicarbonate. Lithium ions (50 mmol 1−1) inhibited bicarbonate‐dependent photosynthetic oxygen evolution but this inhibition was overcome at saturating bicarbonate concentrations. Bicarbonate‐dependent photosynthetic oxygen evolution was also inhibited by lithium ions in cells ofPhaeodactylumgrown in high CO2, (5 % v/v). Acetazolamide and ethoxyzolamide were potent inhibitors of carbonic anhydrase in cell extracts. At pH 8.0 the K0.5(the concentration of inorganic carbon required for 50% or the maximal rate of photosynthetic oxygen evolution) was increased from 53 to 542 μmol I−1in the presence of ethoxyzolamide whereas in the presence of acetazolamide the K0.5.(CO2) increased to 130 μmol 1−1. In the presence of ethoxyzolamide the internal dissolved inorganic carbon (DIC) concentration was increased but this increase was prevented in the presence of lithium ions when bicarbonate transport into the cell is inhibited. These results are in agreement with bicarbonate transport across the plasmalemma and intracellular carbonic anhydrase increasing the steady‐state flux of CO2from inside the plasmalemma to ribulose‐1,5‐bisphosphate carboxylase‐oxygenase by facilitating the interconversion of HCO−3and CO2.
Effects of light and temperature on photosynthesis of the nuisance algaCladophora glomerata(L.) Kutz from Green Bay, Lake Michigan
Authors: LESTER WILLIAM W. , ADAMS MICHAEL S. , FARMER ANDREW M. 
Published: April 2006

summarySeasonal measurements of light‐ and temperature‐dependence of photosynthesis of the nuisance algaCladophora glomerata(L.) Kutz were determined under laboratory conditions with algal samples collected from lower Green Bay, Lake Michigan. Photosynthesis rates were determined using oxygen difference in water circulated around the speciments. Photosynthesis reached light saturation at about 790 μmol photons m−2S−1(PAR) and had a temperature optimum between 28 and 31°c; maximum rates were 25–50 mg O2g dwt−1h‐1. These parameters varied seasonally with water temperatures. There was no evidence for a decline in photosynthetic rate with increasing temperature over the ranges used in this study. It is concluded that, in this instance, such an effect is not responsible for the mid‐season decline of this species. Other effects, such as those of respiration, photorespiration and phenology may, therefore, be important.
Use of carotenoid ratios, ethylene emissions and buffer capacities for the early diagnosis of forest decline
Authors: WOLFENDEN JENNIFER , ROBINSON DEBORAH C. , CAPE J. N. , PATERSON I. S. , FRANCIS B. J. , MEHLHORN H. , WELLBURN A. R. 
Published: April 2006

summaryNorway spruce trees were sampled at twelve sites in Western Europe; each site was known to have been exposed to different levels of atmospheric pollutants. Amongst a wide range of other tests, ratios of needle pigments and buffering capacity were measured in needle samples taken from each site and gas samples taken from similar twigs were subsequently analysed for hydrocarbons. Rates of ethylene emissions were low from needles in relatively unpolluted areas and higher at sites experiencing frequent ozone episodes, higher rainfall acidity or elevated levels of primary pollutants. A similar trend was observed for certain pigment ratios, and a strong correlation was found between ethylene emissions and the ratios of violaxanthin to antheraxanthin. The buffering capacities of 2‐year‐old needles did not differ in any consistent way between sites. In current‐year needles, alkaline buffering was significantly reduced at polluted sites but no significant site‐related trend towards acidic buffering was apparent. The relative value of each of the three tests as early diagnostic indicators of pollutant damage is discussed.
Cell‐wall‐bound peroxidase activity in roots of mycorrhizal Allium porrum
Authors: SPANU P. , BONFANTE‐FASOLO P. 
Published: April 2006

summaryThe activity of cell‐wall‐bound peroxidase in Allium porrum L. roots was measured during root growth and development of vesicular–arbuscular mycorrhiza with Glomus versiforme (Karst.) Berch. The peak of activity in infected plants was higher than in non‐infected ones and occurred during the initial stages of fungal penetration. When the infection was established and the roots highly colonized the activity decreased to the levels in non‐mycorrhizal roots. Ultrastructural localization using diaminobenzidine revealed an increase in the electron‐dense deposits in the middle lamella corresponding with fungal penetration. No activity was seen in the matrix deposited around the intracellular fungal structures. The overall distribution of peroxidase activity was the same in mycorrhizal and non‐mycorrhizal roots.
Fluoride‐induced enhancement and inhibition of photosynthesis in four taxa of Pinus
Authors: DOLEY D. 
Published: April 2006

summary Pinus elliottii Englem. var. elliottii (PEE) and three varities of Pinus caribaea Morelet [var. caribaea Barr, et Golf. (PCC), var. bahamensis Barr. et Golf. (PCB) and var. hondurensis Bafr. et Golf (PCH)] were grown for a total of 125 days under gaseous hydrogen fluoride at 0.0, 1.2, 1.8.and 4.3 μg F m−3. Apparent photosynthesis was measured on 10–12 plants in each taxon and treatment during the last 10 days of the experiment, using needles free from visible injury that had matured before (old) or during the experiment (young). Rates of apparent photosynthesis were significantly greater in young needles of PCB and PCH exposed to 1.2 than to 4.3 μg F m−3, and in old needles of PCH exposed to 1.2 than to 0.0, 1.8 and 4.3 μg F m−3. Chlorophyll concentrations in old needles were consistently lower than those in young needles, but varied less with changes in ambient fluoride concentration, differences in photosynthetic rates of PCB, PCC and PCH corresponded generally with differences in concentrations of chlorophylls a, b and (a+b). Ambient fluoride concentrations less than about 1 μg F m3 appear unlikely to have deleterious short‐term effects on chlorophyll concentrations and photosynthesis in these taxa.