bluuebunny/crossref_metadata_2025_split huggingface dataset:
Histological determination of ozone injury symptoms of primary needles of giant sequoia (Sequoiadendron giganteum Bucch.)
Authors: EVANS LANCE S. , LEONARD MICHAEL R. 
Published: April 2006

summaryGiant sequoia (Sequoiadendron giganteum Bucch.) is a unique resource that exists only in groves on the western slopes of the Sierra Nevada in California. Since Sequoia and King's Canyon (SEKI) National Parks are experiencing ozone concentrations phytotoxic to some species of Pinus, we performed several experiments on S. giganteum seedlings to determine the ozone sensitivity of their primary needles and their suitability as sensitive bioindicators during the seedlings stage of growth. Current‐year seedlings were fumigated in open‐top chambers during 1986 and 1987. Treatments included (1) carbon‐filtered air (no ozone); (2) ambient ozone; (3) 1.5 times the ambient amount of ozone; and (4) a no‐chamber treatment. In 1986, ozone doses ranged from 100 to 221 ppm h−1while those in 1987 ranged from 125 to 216 ppm h−1. In neither year did the percentages of plasmolysed cells correlate with ozone dose. In 1986, however, the percentages of amorphously stained and dead cells taken together showed a significant (P= 0.028; r2= 0.721) linear response to dose (y = 29.9 + 0.260x). In the 1987 fumigation, there was no significant relationship between ozone dose and the percentage of either amorphously stained or dead cells. The narrow range of ozone doses (from 125 to 216 ppm h−1) and the short duration of exposure (48 d) may have resulted in high percentages of amorphously stained cells (between 61 and 81 %). In both experimental fumigations, higher ozone doses killed more cells in the needles. When data of the percentages of dead cells from both experiments were pooled, there was a statistically significant (P= 0.0036) correlation coefficient of 0.744 with a line slope of y = 2.472 + 0.051x. There was no evidence of a curvilinear response. The overall anatomy of primary needles from SEKI was similar to that of those sampled from the fumigation experiment; SEKI samples exhibited a high degree of amorphous cell staining (between 67 and 81 %). Cell death averaged 5.1% from all the park samples, a percentage within to the range of cell death (0.9–6.2 %) in the ambient air chambers.
Leaf demography and the seasonal internal cycling of nitrogen in sycamore (Acer pseudoplatanus L.) seedlings in relation to nitrogen supply
Authors: MILLARD P. , PROE M. F. 
Published: April 2006

summaryThe dynamics of the seasonal internal cycling of nitrogen (N) in Acer pseudoplatanus were studied in relation to N supply and leaf demography. Trees were grown in sand culture, and throughout 1988, supplied with either 1.0 mol N m −3(Low N) or 6.0 mol N m −3(High N), labelled with 15N to 5.0 atom %, in order to precondition their growth and capacity for N storage over the winter period. In 1989, the initial spring growth of leaves was independent of the current N supply at either 1.0 or 6.0 mol N m−3, and depended only upon the N supplied in 1988. A net loss of 15N from perennial tissues and recovery of 15N in the growing leaves confirmed that the current N supply had no effect on the remobilization of N from winter stores in the roots and stem. After 22 May 1989, remobilization of stored N for leaf growth had ceased and leaf demography was influenced by the current N supply. Plants preconditioned to 6.0 mol N m −3in 1988, but receiving only 1.0 mol N m−3in 1989, were unable to sustain previous leaf growth after 22 May and there was a decrease in leaf mass and area due to leaf abscission. In contrast, trees preconditioned with 1.0 mol N m−3in 1988, but receiving 60 mol N m−3in 1989 greatly increased their leaf growth after 22 May. This was a consequence of the stimulation by N uptake of growth of many small leaves on axillary shoots at the base of the canopy. Although leaf number increased, mean area per leaf decreased.The trees were inefficient at withdrawing N from senescing leaves in both years, allowing most of the N to fall from the tree with the leaves. The spring remobilization of N, therefore, was dependent largely upon the direct uptake of N into the stem and roots, in late summer and autumn, for storage over the winter period. The results are discussed in relation to leaf demography and the nitrogen use efficiency of deciduous trees.
Induction of cadmium tolerance by acclimation transferred between ramets of the clonal fern Salvinia minima Baker
Authors: OUTRIDGE P. M. , HUTCHINSON T. C. 
Published: April 2006

summaryChanges in the cadmium tolerance of ‘daughter’ ramets resulting from prior acclimation to Cd by ‘parent’ plants were examined in the clonal fern Salvinia minima Baker. In two experiments, parents were acclimated to 0, 10, 25 or 50μg Cd l−1, and subsequently produced daughter ramets in a Cd‐free medium. Parent acclimation to 25μg Cd l1increased the daughter ramets' tolerance index by 13–17% (based on chlorophyll‐a content), while 10μg Cd l−1had no effect. Acclimation to 50μg Cd l−1produced ‘carry‐over’ toxicity (i.e. reduced growth and chlorosis) in daughter ramets in Cd‐free solution. Their tolerance index was 28 % higher than the control when tested with 15 μg Cd l−1in one experiment. In contrast, there was no such increase when they were tested with 25μg Cd l−1in a second experiment. This may be due to the higher Cd concentration in the latter test, combined with carry‐over toxicity, overwhelming induced tolerance. ‘Tolerant’ daughter ramets, which maintained higher chlorophyll concentrations during Cd exposure than control ramets, also grew slower, a seeming contradiction. A possible explanation is that induced tolerance, involving protection of chlorophyll synthesis by phytochelatin binding with Cd, has an accompanying metabolic cost due to glutathione depletion.These data may be the first evidence of (a) induced metal tolerance in a vascular plant other than grasses, and (b) increased metal tolerance of daughter ramets due to acclimation of their parent clones. In patchily metal‐contaminated habitats, the latter phenomenon may benefit rhizomatous clonal plants over non‐integrated clones or annual plants. Daughter ramets connected to acclimated parents may be more likely to survive in other contaminated patches, increasing the possibility that the clone will grow into uncontaminated areas.
A reassessment of the influence of NAA on aerenchyma formation in maize roots
Authors: JUSTIN S. H. F. W. , ARMSTRONG W. 
Published: April 2006

summaryThe effect of 1‐naphthylacetic acid (NAA: 10−9to 10−5M) on extension growth and aerenchyma formation in second‐whorl adventitious roots of Zea mays L. (cv. LG11) was examined. Treatments were applied continuously for 12, 8 or 3 d following initial periods in NAA‐free solution. NAA at 10−9M stimulated root elongation, but with increasing concentrations there was a progressive inhibition of growth. Gas space was increased by low levels of NAA and appeared to be reduced by the higher levels. When root length was taken into consideration, however, no NAA treatment produced less aerenchyma than would be expected from control roots of similar length in stagnant NAA‐free media, and there was some evidence that the NAA had promoted aerenchyma formation. Since NAA promotes ethene formation in roots the results would accord with an NAA induced ethene effect.
Aberrant sieve element differentiation in primary leaves of Vigna sinensis Endl. affected by colchicine
Authors: GALATIS B. 
Published: April 2006

summaryIn primary leaves of Vigna sinensis Endl. seedlings growing in the presence of colchicine, some giant polyploid cells at the phloem pole of the vascular bundles differentiate into an extraordinary cell type acquiring most of the prominent features of the sieve elements. These aberrant sieve elements (a‐SEs) show some exceptional features not found in normal sieve‐tube elements. A heavy secondary thickening is deposited on their walls, which in surface view exhibits a reticulate or ‘pitted’ appearance. The thickenings reach the same depth into the cytoplasm and show a diffuse orientation of cellulose microfibrils. Amorphous callose is deposited around some fine cytoplasmic strands penetrating the secondary wall up to the primary one along the longitudinal and particularly the transverse walls. In the latter walls sieve pores are not formed. At first, the a‐SEs undergo a partial protoplasmic degradation like normal sieve‐tube elements but finally autolyse completely. During this process, the major portion of the unmasked primary and secondary wall is dissolved.The observations show that (a) a vascular bundle initiation and development proceeds in the affected primary leaves, in the absence of cell divisions.‘Vascular bundles' are formed consisting of a single row of cells, in which a‐SE differentiation dominates. (b) The ‘sieve element differentiation’ is initiated without differential divisions. (c) Although the microtubules arc absent, the cells determined to become a‐SEs activate another morphogenetic mechanism to control a more or less patterned deposition of a secondary wall layer.
Fungal decomposition of attached angiosperm twigs
Authors: GRIFFITH G. S. , BODDY LYNNE 
Published: April 2006

summaryInterspecific interactions between fungi frequently isolated (isolation frequency < 5 %) from dead, attached ash twigs were studied on agar and in twigs at different water potentials in the laboratory, and in twig lengths resuspended in the field. Under laboratory and field conditions the following observations were made. The main primary colonizers of dead attached ash twigs, Phomopsis platanoidis Died., Fusarium lateritium Nees. and Sp. 12, did not replace each other. Two of the common secondary colonizers, Libertella fraxinea Oganova and Acremonium sp. A, did not actively replace primary colonizers, except that L. fraxinea partially replaced P. platanoidis when associated with bacteria. The secondary colonizer Peniophora lycii (Pers.) v. Holm & Litsch was, however, more combative and replaced all other species, provided that water potential was not lower than –4 MPa. There was some evidence that under field conditions P. lycii, arriving via the air spora could not replace P. platanoidis or Sp. 12; it apparently required a well established base in the resource. However, it could replace F. lateritium and consequently gain a suitable foothold in twigs naturally colonized in the field. Also, P. lycii demonstrated polar growth in twigs, progressively replacing other species.Active mechanisms by which fungi could resist replacement included the production of pseudosclerotial plates by P. platanoidis and the production of a volatile antifungal agent by Sp. 12. There was also some evidence that other fungi, in particular F. lateritium, produced diffusible antifungal substances, or altered growth conditions, which inhibited other fungi.
Detection of extracellular cellulolytic and proteolytic activity in ectomycorrhizal fungi and Heterobasidion annosum (Fr.) Bref.
Authors: MAIJALA P. , FAGERSTEDT K. V. , RAUDASKOSKI M. 
Published: April 2006

summaryProteolytic and cellulolytic activities were studied in the ectomycorrhizal fungi Amanita regalis (Fr.) Maire, Paxillus involutus (Batsch ex Fr.) Fr. and Suillus bovinus (L. ex Fr.) O. Kuntze and the necrotrophic root pathogenic fungus Heterobasidion annosum (Fr.) Bref. using plate assays, native gel electrophoresis and substrate gel replicas. All the fungi produced carboxymethyl cellulose (CMC)‐hydrolysing activity. Two CMCase bands were detected in H. annosum and P. involutus and one in A. regalis and S. bovinus. In the plate assays, extracellular proteolytic activity was found in all the fungi and the activities were visualized in H. annosum and A. regalis after native polyacrylamide gel electrophoresis.
Vesicular–arbuscular mycorrhizas respond to corn and soybean cropping history
Authors: JOHNSON NANCY COLLINS , PFLEGER F. L. , CROOKSTON R. KENT , SIMMONS STEVE R. , COPELAND PHILIP J. 
Published: April 2006

summaryCommunities of vesicular‐arbuscular (VA) mycorrhizal fungi were studied in a long‐term crop rotation experiment at two locations (Waseca and Lamberton, Minnesota, USA). Spores of mycorrhizal fungi were counted and identified in experimental plots with a cropping history of either corn (Zea mays L.) or soybean [Glycine max (L.) Merrill]. Mycorrhizal fungal communities were affected by both location and cropping history. At Waseca, Glomus aggregation Schenck & Smith, G. leptotichum Schenck & Smith and G. occultum Walker spores were more abundant in soil with a corn history than a soybean history, while spores of G. microcarpum Tul. & Tul. exhibited the reciprocal pattern. Approximately 90% of the spores recovered at Lamberton were G. aggregation and did not vary with crop history. However, the spores of three other species: G. albidum Walker & Rhodes, G. mosseae Gerdemann & Trappe, and G. occultum, were more abundant in plots with a corn history than a soybean history. Densities of G. aggretatum spores were negatively correlated with soil pH at Waseca, but were unrelated to pH at Lamberton were the mean soil pH was lower. Our results indicate that mycorrhizal fungal species are individualistic in their responses to cropping history and edaphic factors.
Seed dormancy in Mediterranean Senecio vulgaris L.
Authors: REN Z. , ABBOTT RICHARD J. 
Published: April 2006

summaryFresh seed derived from a Mediterranean population of non‐radiate Senecio vulgaris L. showed strong innate dormancy over a wide temperature range. In contrast, fresh seed of British S. vulgaris exhibited < 80% germination at 20 °C. Dormancy in Mediterranean seed was overcome by: prolonged storage at 15 °C and above; a short stratification treatment (2 wk at 4 °C); prolonged leaching with water; treatment with gibberellic acid (GA3) alone (and with kinetin); and to a lesser extent, by wounding (i.e. removal of a small portion of the fruit and seed coat). A petroleum ether extract from fresh Mediterranean seed strongly inhibited the germination of previously non‐dormant seed (of British origin). This implies that dormancy may be caused by an inhibitor present in the embryo or seed coat which might act by preventing the synthesis or liberation of gibberellins required for germination. The innate dormancy exhibited by seed of non‐radiate Mediterranean S. vulgaris, enables the species to adopt a winter annual life cycle which is typical of Mediterranean ephemerals.
The use of the fluorescent dye, 3,3′‐dihexyloxacarbocyanine iodide, for selective staining of ascomycete fungi associated with liverwort rhizoids and ericoid mycorrhizal roots
Authors: DUCKETT JEFFREY G. , READ DAVID J. 
Published: April 2006

summaryThe lipophilic fluorochrome 3,3′dihexyloxacarbocyanine iodine [DiOC6(3)], previously used to visualize mitochondria and ER in animal and plant tells, when applied at concentrations of 0.01–5 μg ml−1selectively stains ascomycetous hyphae in ericaeous roots and in the rhizoids of liverworts in the families Lepidoziaceae (both tropical and temperate species), Calypogeiaceae, Adelanthaceae, Cephaloziaceae and Cephaloziellaceae. Basidio‐mycetes forming endophytic associations with liverworts and ectomycorrhizas in seed plants, are stained with DiOC6(3) only at concentrations at and above 50 μg ml−1. VA mycorrhizal fungi in liverworts, pteridophytes and angiosperms fail to stain. Hyphae of the ericoid mycorrhizal fungus, Hymenoscyphus ericae, grown in axenic culture, are stained with much lower concentrations of DiOC6(3) than are those of a range of ectomycorrhizal fungi, an orchid fungus and Oidiodendron griseum which has been reported occasionally to form ericoid mycorrhizal associations. In contrast to other fluorescent probes that recognize fungal wall components, DiOC6(3) is a vital stain of fungal cytoplasm. Greater membrane permeability, compared to that in other fungi, is the likely basis for the selective staining of Hymenoscyphus ericae and the root and rhizoid‐inhabiting ascomycetes with this dye. DiOC6(3) offers a rapid means for identifying intracellular ascomycetous mycorrhizas and for determining the distribution of living hyphae within these associations.
Localization of aluminium in the roots of Norway spruce [Picea abies (L.) Karst.] inoculated with Paxillus involutus Fr.
Authors: HODSON M. J. , WILKINS D. A. 
Published: April 2006

summaryNorway spruce [Picea abies (L.) Karst.] seed lots from populations growing on acid soil in the Black Forest (BF), and from a calcareous soil in the Schwäbische Alb (SA), West Germany, were grown in perlite and treated with 0 and 6 mM Al. Some of the plants were inoculated with the fungus Paxillus involutes Fr., while some were not. Fungus was associated with the roots of the inoculated plants, but mycorrhizas did not form.Mineral element distribution in the roots was investigated using X‐ray microanalysis of freeze substituted sections in TEM. Seven elements were detected: aluminium, silicon, phosphorus, sulphur, chlorine, potassium, and calcium. Aluminium was almost entirely confined to the cortical cell walls, and was not detectable inside the endodermis. The presence of P. involutus significantly increased aluminium concentrations in the cortical cell walls of both seed lots, while silicon concentrations in the aluminium‐tolerant (BF) plants increased in response to aluminium treatment.
Effects of summer ozone on membrane lipid composition during subsequent frost hardening in Norway spruce [Picea abies (L.) Karst]
Authors: WOLFENDEN J. , WELLBURN A. R. 
Published: April 2006

summaryNorway spruce trees [Picea abies (L.) Karst] were exposed to ozone during the summers of three consecutive years and the fatty acid composition of the chloroplast membrane lipid, monogalactosyl diglyceride (MCDG) was analysed over the last 14 months. Significant variations in the degree of unsaturation and the percentage of linolenic acid (18:3) were not found, either on a seasonal basis or in relation to ozone treatment. The proportion of octadecatetraenoic acid (18:4) and other Δ5fatty acids increased during autumn in trees grown in filtered air, but this seasonal effect was less pronounced in ozone‐treated trees. The ratio of two forms of linoleate, Δ5,918:2 and Δ9,1218:2 also increased significantly during the frost hardening period but not in trees previously exposed to ozone. This implies that two separate biosynthetic pathways exist, one for the Δ12and one for the Δ12desaturated series, which operate at different relative rates, depending on environmental conditions. It is suggested that ozone may interfere with the biosynthesis of 18:4 during frost hardening by inhibiting the Δ5desaturation of oleate.
Seasonal uptake and allocation of phosphorus in Eriophorum vaginatum L measured by labelling with 32P
Authors: JONASSON SVEN , STUART CHAPIN F. 
Published: April 2006

summarySeasonal measurements of phosphorus (P) pools in the tussock‐forming sedge Eriophorum vaginatum L. indicated low annual P uptake, but pronounced fluxes of P to growing biomass from below‐ground stores in spring, and a return in autumn. Additions of 32P to tussocks in early spring and mid summer confirmed this deduction. Addition of 32P caused a rapid incorporation of about 10% of the labelled P in the tillers within a few days. Subsequent uptake was negligible, presumably because the 32P not immediately absorbed was fixed in the soil and unavailable to plants. This demonstrates that nutrient pulses were more important than steady‐state mineralization in supporting P uptake by Eriophorum vaginatum. After the 32P additions, roots initially retained 60% of the total 32P taken up. During the following weeks, part of the 32P was transported slowly to stem bases and leaf sheaths, the principal storage organs. A lower proportion was transported to the leaf blades. We suggest that storage and recirculation of nutrients are the main sources of the annual nutrient supply to growth of E. vaginatum under normal field conditions, where P fixation in the soil and low rate of P diffusion towards the roots limit P uptake from soil except during periods of pulsed release.
Environmental factors influencing photosynthetic efficiency of the micro red alga Porphyridium cruentum (Agardh) Nägeli in light‐limited cultures
Authors: LEE EDMUND T. Y. , BAZIN MICHAEL J. 
Published: April 2006

summarySteady state growth of the red alga Porphyridium cruentum was obtained in light‐limited chemostat cultures at different temperatures, pH and salinities over a range of specific growth rates. Geometric design of the reactors was found to have no effect on the yield and photosynthetic efficiency (PE) of the biomass. Under optimal growth conditions, that is at 23 °C, pH 8 and NaCl concentration of 0.42 M, the maximum specific growth rate was 0.065h−l which corresponded to a generation time of 10.7 h. With a given light input the biomass output rate was found to be constant over the range of specific growth rates studied. The values of the maximum growth yield (YG) and maximum PE of P. Cruentum were in the range of 0.0064–0.0074 g kj−1 and 13.4–15.5% respectively, when growth was optimal. This PE value corresponds to a quantum demand of 15 per O2 molecule evolved. Different temperatures, pH and salinities were demonstrated to cause a 1.5 to 2‐fold variation in the maximum PE. The maintenance energy was found to be virtually zero under all conditions.
Identification and quantification of trehalose in vesicular‐arbuscular mycorrhizal fungi by in vivo13C NMR and HPLC analyses*
Authors: BÉCARD G. , DONER L. W. , ROLIN D. B. , DOUDS D. D. , PFEFFER P. E. 
Published: April 2006

summaryNatural abundance in vivo13C NMR spectra were obtained from spores of three species of VA mycorrhizal fungi: Glomus intraradix Schenck & Smith, Glomus etunicatum Becker & Gerdemann and Gigaspora margarita Becker & Hall. The presence of trehalose was established in the spectra of Gl. etunicatum and Gi. margarita. HPLC analyses supported these observations and indicated that Gl. intraradix spores also contained small amounts of trehalose, not readily detectable by 13C NMR. Trehalose constituted between 0.06% and 1.6 %(w/w) of the spore dry weight, depending on the species. Only trace amounts of other sugars, including glycerol, were detected. An in vivo NMR time course experiment indicated that trehalose was readily utilized during spore germination.
The effect of soil water potential on seedling growth of some British plants
Authors: EVANS CERI E. , ETHERINGTON JOHN R. 
Published: April 2006

summarySeedlings of 15 species from a range of habitats contrasting in soil water status were grown at known soil water matric potentials ranging from near field capacity to the permanent wilting potential (−0.05. −0.5, −1.0 and − 1.5 MPa). Root and shoot growth were differentially very sensitive to soil water matric: potential: root growth continued at lower soil water matric potentials than shoot growth. All Species from drier habitats established better in drier soils than wetland species, with increased root growth in drier soils in contrast to decreased root growth of wetland species in drier soils. Seed size was thought to be an important factor in determining establishment in dry soils; the only wetland species to maintain substantial root growth in dry soils had comparatively large seeds. The seedling growth responses were compared with the same species' germination responses in relation to the above range of soil water matric potentials (established in a previous study). Sensitivity to soil moisture may occur at the germination or seedling stage of growth.