bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of protein patterns in non‐mycorrhizal and vesicular–arbuscular mycorrhizal roots of red clover
Authors: ARINES J. , PALMA J. M. , VILARIÑO A.
Published: April 2006

A comparison of the protein content and patterns in root extracts from non‐mycorrhizal and vesicular‐arbuscular mycorrhizal [Glomus mosseae (Nicol. et Gerd.) Gerd. et Trappe] red clover (Trifolium pratense L.) has been made. Soluble protein content was higher in mycorrhizal than in non‐mycorrhizal roots. After separation by DEAE‐cellulose chromatography and electrophoretic analysis, several additional polypeptides appeared in mycorrhizal extracts. In addition, it seems that one of the additional proteins was a plant‐induced superoxide dismutase isozyme.
Magnetic resonance imaging of leaves
Authors: VERES JOHN S. , COFER GARY P. , JOHNSON G. ALLAN
Published: April 2006

Several aspects of leaf anatomy and morphology make it difficult to image leaves with magnetic resonance imaging. Since most fully expanded leaves contain much intercellular air space and are often thin in one plane, relatively few water protons are available to provide signal. Their heterogeneous structure and the presence of many air‐water interfaces cause imaging problems as a result of differences in magnetic susceptibility of tissues and cells. Significant progress has been made in overcoming these difficulties, primarily by greatly reducing the echo time, permitting in vivo imaging of leaves at 7 and 9.4 Tesla with an in‐plane resolution of less than 15 μm2. Examples are shown and the potential for gaining information regarding in vivo water relations of leaves is discussed.
Rates of water uptake into the mature root system of maize plants
Authors: VARNEY G. T. , CANNY M. J.
Published: April 2006

A new method of measuring water uptake by roots is applied to whole root systems of large maize plants growing in aeroponic (mist) culture. The method depends on the build‐up of concentration of dye (sulphorhodamine G) on and in the root surface, when it is fed in the mist. Water enters the roots rapidly, but the dye is separated from the water by osmotic filtration and penetrates the apoplast only by very slow diffusion. The dye accumulates progressively with time on roots on transpiring plants, but not on roots of non‐transpiring controls. The rate of accumulation of dye at a place on the root is translated to a flux of water into the root at that place, using the concentration of dye in the mist. Water fluxes were measured into first‐order branches and axes over the root system and expressed both as fluxes per unit length and per unit surface of root. Values are consistent with those found by potometric methods for limited samples of young plants. The variance of the measurements is quite large, possibly reflecting real heterogeneities in water uptake throughout the root system. The maximum water uptake achieved by a few branches was 40 μl h−1 cm−2 root. On average, flux into axes and branches was the same throughout the root system, at about 5 μl h−1 cm−2. The region of the axis at which the late metaxylem vessels mature and become conducting coincides with the region where the branches become active in water uptake (20–30 cm from the tip). Proximal to this, the branches collect about eight times as much water as the axis, having about eight times the surface area. The zone of maximum water collection by branches and axis is 30–60 cm from the tip (6–8 μl h−1 cm−1 axis). In the older, more proximal regions, water collection drops to about a quarter of this.
The taxonomic and evolutionary significance of leaf longevity
Authors: ROGERS R. W. , CLIFFORD H. T.
Published: April 2006

The half‐lives of leaves of 202 taxa of vascular plants were estimated mostly from the literature and ranged from 1 to 350 wk. The longevity of leaves in the plant groups studied is in the order Pinophyta > Pteridophyta > Liliatae > Magnoliatae. Substantial differences are evident between the superorders of flowering plants proposed by Dahlgren and the subclasses proposed by Cronquist. The mean leaf half‐life for families of Magnoliatae was shown to be inversely related to their Advancement Index. Length of life of leaves, therefore, appears to have taxonomic significance, with more primitive vascular plants tending to have longer‐lived leaves than the more advanced. The ecological significance of leaf half‐life is less clear, except in that annual leaf fall is not necessarily associated with deciduousness. The capacity to shed individual leaves may give the angiosperms a flexibility in environmental response which allows them a competitive advantage over the gymnosperms except in the most stressful habitats.
Interactions of fungi with toxic metals
Authors: GADD G. M.
Published: April 2006

This review details the major interactions of fungi with toxic metal species. Physico‐chemical and biological aspects are discussed including definitions and classification of metals in biological contexts, mechanisms of metal fungitoxicity, resistance and tolerance, environmental influences and the occurrence of fungi in metal‐polluted habitats. Cellular interactions include extracellular precipitation and complexation, binding to cell walls, transport of monovalent and divalent metal cations, intracellular fates of toxic metal species (including metal‐binding proteins and peptides, and vacuolar compartmentation), and metal transformations including organometal(loid) synthesis. Significant interactions between metals and mycorrhizal fungi and macrofungi are summarized with reference to the amelioration of plant phytotoxicity and metal accumulation respectively. Biotechnological aspects of metal‐fungal interactions relate to the biological treatment of metal‐contaminated effluents and waste streams for metal removal/recovery and environmental protection.

CONTENTS

Summary

I.
Introduction
25

II.
Definition and classification of metals
26

III.
Fungitoxicity of metals
28

IV.
Interactions between toxic metals and fungi
32

V.
Mycorrhizal interactions with toxic metals
45

VI.
Accumulation of metals by macrofungi
45

VII.
Biotechnological aspects of fungal metal accumulation
46

Acknowledgements
51

References
51

Note added in proof*
60
Identification of cytoskeletal components in pine ectomycorrhizas
Authors: TIMSONEN SARI , FINAY RROGER D. , SÖDERSTRÖM BENGT , RAUDASKOSKI MARJATTA
Published: April 2006

Ectomycorrhizal associations were synthesized between pine seedlings and the fungi Suillus bovinus (L.) ex Fr. or Paxillus involutus (Batsch ex Fr.) Fr. Immunoblotting of polypeptides separated electrophoretically from crude tissue extracts revealed the abundant presence of tubulin and actin in ectomycorrhiza and lower amounts in the fungal strands surrounding the ectomycorrhizal roots. In ectomycorrhiza the α‐tubulins from fungal hyphae and plant cells were clearly distinguishable but such discrimination was not possible for β‐tubulin or actin due to the similar mobility of proteins originating from the conifer and fungal tissues. Young ectomycorrhizal short roots were fixed while still attached to the seedlings and, using indirect immunofluorescence microscopy with tubulin antibodies, microtubules were detected in both the conifer cells and in fungal hyphae. In the host plant cytoplasmic and spindle microtubules were visualized in meristem cells and in differentiating vascular tissue but not in the cortical cells. In symbiotic hyphae the microtubule tracks and spindles of dividing nuclei were clearly distinguished in the mantle hyphae in the tip region of the short roots. In the Hartig net hyphae microtubule tracks changed to a less clear, reticulate structure. Actin was visualized as long filaments in vascular tissue cells and as small microfilament bundles in mantle hyphae. Short microtubules and actin dots were detected in cytoplasm‐containing hyphae on the strand surface. The possible role of the cytoskeletal elements in the maintenance of the ectomycorrhizal association is discussed.
Wound‐healing in Vaucheria longicaulis Hoppaugh var. macounii Blum.
Authors: TORNBOM LAURIE , OLIVEIRA LUSI
Published: April 2006

Differential interference contrast microscopy of the cytoplasm of Vaucheria longicaulis Hoppaugh var. macounii Blum reveals the presence of cable‐like strands (tracks). The cytoplasmic tracks are orientated parallel to the length of the filament, and the organelles are closely associated and appear to move along them. Nuclei, mitochondria and Rhodamine B‐positive bodies (RBIs) interact with a single track. Chloroplasts are closely associated with several tracks, although preferential association with one of the tracks is clearly observed. In uncut filaments, the different classes of organelles move independently of one another and travel at different speeds. Chloroplasts, mitochondria, RBIs, and smaller inclusions (SSIs) exhibit a bulk pattern of motion characterized by brief reversals in their primary pattern of movement that do not affect their final direction of travel. Nuclei move independently of each other and do not reverse their direction of movement. In cut filaments, cytoplasmic track density and relationship to organelles in the wound region during stage 1 is similar to that in uncut filaments. The cytoplasmic tracks extend into the wound‐healing vesicle cytoplasm. Mitochondria and similarly‐sized organelles move rapidly (in bulk) toward the wound site and into the wound‐healing vesicle. In stage 2, an increase in cytoplasmic track density is observed in the wound region, and bulk movement of mitochondria and RBIs occurs toward the wound site. Nuclei also move in bulk, unidirectionally toward the wound. Organelle retraction from the wound is restricted to the chloroplasts.

Both uncut and cut filaments were treated with the cytoskeleton depolymerizers Cytochalasin B and Oryzalin to determine the role(s) of microfilaments and microtubules respectively in organelle movement and the overall role of the cytoskeleton in the wound‐healing process. In uncut filaments, cytoplasmic streaming is severely reduced by both Cytochalasin B and Oryzalin, with the greatest reduction observed following cytochalasin B treatment. In cut filaments Cytochalasin B shows a greater effect on chloroplasts, mitochondria, and RBIs behaviour, while Oryzalin preferentially affects the nuclei. The results indicate that the bulk movement of chloroplasts, mitochondria and RBIs in uncut filaments may be microfilament‐based, and the movement of nuclei microtubule‐based.
The marine lichen Lichina confinis (O. F. Müll.) C. Ag.: ultrastructure and localization of nitrogenase, glutamine synthetase, phycoerythrin and ribulose 1, 5‐bisphosphate carboxylase/oxygenase in the cyanobiont
Authors: JANSON SVEN , RAI AMAR N. , BERGMAN BIRGITTA
Published: April 2006

Thallus ultrastructure and the localization of proteins involved in photosynthesis, N2 fixation and ammonia assimilation was studied in the Lichina confinis (O. F. Müll) C. Ag.‐Calothrix symbiosis. The lichen thallus showed profuse branching. Within this, the cyanobiont was located in the cortical zone. Haustoria were frequently observed in contact with vegetative cells of the cyanobiont but not with heterocysts. An extensive mucilage layer containing numerous vesicles occurred around cyanobiont cells. Immunolabelling showed nitrogenase to be exclusively located in heterocysts of the cyanobiont and the free‐living Calothrix sp. Glutamine synthetase (GS) levels in the cyanobiont were found to be drastically decreased compared to the levels in free‐living (cultured) Calothrix sp. Such a decrease was more prominent in mature parts of the thallus than in the apical region. Rubisco was mostly located in carboxysomes of the vegetative cells of the cyanobiont. There were relatively low levels of Rubisco in the cytoplasm of vegetative cells, while heterocysts showed negligible levels. In free‐living (cultured) Calothrix sp., phycoerythrin (PE) was found to be located along the thylakoid membranes both in vegetative cells and heterocysts. Cyanobiont cells showed a similar pattern but the levels were relatively lower.
Infection structures of fungal plant pathogens – a cytological and physiological evaluation
Authors: MENDGEN KURT , DEISING HOLGER
Published: April 2006

Many fungi differentiate specific infection structures in order to infect the host plant. The spore attaches to the host surface, the cuticle, and the germ tube may recognize suitable penetration sites, over which an appressorium is formed. Additional wall layers in appressoria of many fungi suggest that this structure supports increasing pressure during the penetration process. During appressorium formation, synthesis of polymer‐degrading enzymes is often initiated. Cutinases, cellulases and pectin‐degrading enzymes can be formed in a developmentally controlled or adaptive, i.e. substrate‐dependent, fashion. The penetration hypha develops below the appressorium. This hypha has a new wall structure and exhibits features which serve to breach the plant cell wall. However, at present it is not clear whether penetration hyphae arising from appressoria are more efficient in penetration or induce less damage than hyphae which penetrate without detectable special adaptations. The infection hypha differentiates within the host. During differentiation a characteristic set of enzymes is synthesized to enable successful establishment of the host‐pathogen relationship. If, as in most cases, multiple forms of cell wall‐degrading enzymes are formed by the pathogen, mutagenesis or deletion of a gene encoding one of these enzymes very often has no effect on pathogenicity or even virulence. Proof is missing very often that an enzyme is needed at the right time and at the right site of infection.

Events occurring during differentiation of fungal infection structures are reviewed with special emphasis onMagnaporthe grisea, Colletotrichumspp., and rust fungi, and common features which may be of importance to the success of infection are discussed.

CONTENTSSummary193I.Introduction193II.Spore and germ tube195III.The appressorium199IV.The penetration hypha201V.The infection hypha204VI.Future prospects208Acknowledgements208References208
Scutellospora calospora (Nicol. & Gerd.) Walker & Sanders associated with subterranean clover: dynamics of colonization, sporulation and soluble carbohydrates
Authors: PEARSON J. N. , SCHWEIGER P.
Published: April 2006

Two time‐course experiments were conducted to investigate the relationship between colonization and sporulation by Scutellospora calospora (Nicol. & Gerd.) Walker & Sanders colonizing roots of subterranean clover (Trifolium subterraneum L.).

The percentage of root length colonized by S. calospora increased up to 49 d in expt 1 and 32 d in expt 2 after which it declined. At this stage, there was no further increase in mycorrhizal root length but a sharp increase in non‐mycorrhizal root length. In expt 1, the soluble carbohydrate concentration of the roots decreased during the first 49 d, followed by a sudden increase, coinciding with the decline in the percentage of root length colonized. One week before this the shoot P inflow also decreased. In both experiments, sporulation by S. calospora occurred after the decline in colonization.

During sporulation there is no further spread in colonization within the root, which may result in increases in soluble carbohydrate concentration within the root. Spore formation may be aided by carbon stores located in the external auxiliary bodies formed by species of the genus Scutellospora.
Acquisition of nitrogen by external hyphae of arbuscular mycorrhizal fungi associated withZea maysL.
Authors: FREY BEAT , SCHÜEPP HANNES
Published: April 2006

The objective of this study was to examine the ability of arbuscular mycorrhizal (AM) fungi to take up nitrogen from soil and transport it to the host plant. Maize (Zea maysL.) associated withGlomus intraradicesSchenck and Smith or left uninoculated was grown in containers which were divided by a nylon net into a root compartment and a hyphal compartment. A 40 μm pore size nylon net was used to exclude plant roots while allowing fungal hyphae to grow into soil confined by the net.15N tracer was supplied either as inorganic N or as organic N to the hyphal compartment at a distance of 5 cm from the net.

Inoculation with the AM fungus increased the15N content of maize compared to the non‐mycorrhizal controls when N was applied as (15NH4)2SO4. However, there was no conclusive evidence that AM hyphae could derive N from organic15N sources. Most of the increased N uptake of mycorrhizal plants occurred by hyphal translocation from the hyphal compartment to the root compartment. Higher N uptake by mycorrhizal plants with access to the hyphal compartment was indicated by depletion of total15N in the soil of that compartment. Cutting the extraradical hyphae in the hyphal compartment in order to sever their connection with the host roots decreased the15N uptake of the maize plants. A time‐course study with inorganic15N over 26 d showed thatG. intraradicestransported most of the15N between 10 and 15 d after15N application, whereas the non‐mycorrhizal control plants had a consistently low concentration of15N throughout the period of sampling.

Nitrogen transport by external hyphae of three AM fungi,G. intraradices, Acaulospora laevisGerdemann and Trappe andGigaspora margaritaBecker and Hall associated with maize, was further investigated. The results indicated that different isolates of AM fungi differ in the efficiency of hyphal N transport as a consequence of the different patterns of hyphal spread in the soil or of the different capacity for uptake by unit length of hyphae.
Nitrogen translocation between Alnus glutinosa (L.) Gaertn. seedlings inoculated with Frankia sp. and Pinus contorta Doug, ex Loud seedlings connected by a common ectomycorrhizal mycelium
Authors: ARNEBRANT KRISTINA , EK HANS , FINLAY ROGER D. , SÖDERSTRÖM BENGT
Published: April 2006

Uptake and translocation of nitrogen was studied in laboratory microcosms consisting of Alnus glutinosa (L.) Gaertn., Frankia sp., Paxillus involutus (Fr.) Fr. and Pinus contorta Dougl. ex Loud. P. involutus was shown to form a fully functional ectomycorrhizal association with alder as well as pine, and the seedlings thus became interconnected by a common mycelium.

When microcosms were exposed to 15N2 gas, interplant translocation of 15N was observed in two out of three experiments. 15N2 was fixed by Frankia and translocated to all other parts of the system. In the two experiments in which interplant translocation occurred, between 5 and 15% of the 15N recovered was found in the pine seedlings.

Within seven days, fixed N2 was incorporated into amino acids in the Frankia nodules, translocated to both the A. glutinosa and P. contorta seedlings and incorporated into macromolecules. In alder seedlings, citrulline and ornithine were the free amino acids that had both the highest 15N enrichment levels and concentrations. In pine, glutamine and citrulline had the highest 15N concentrations, and glutamine had the highest level of 15N enrichment. 15N enrichment levels were greatest in the nodules, at between 5.5 and 29% in the different amino acids and 12% in the macromolecular fraction. Enrichment levels decreased with increasing distance from the nodules.

The uptake and translocation of 15N applied as 15NH4Cl to the mycelium was also studied. 15N was incorporated into amino acids in the mycelium and translocated further in this form. Generally, free amino acids had high 15N enrichment levels in the mycelium, decreasing along the translocation pathway. Citrulline and glutamine were the amino acids with highest 15N concentrations in all parts of the system. 15N was also found in the macromolecular fraction.
Impaired nodule function in Medicago polymorpha L. infected with alfalfa mosaic virus
Authors: WROTH J. M. , DILWORTH M. J. , JONES R. A. C.
Published: April 2006

The effects of alfalfa mosaic virus (AMV) on growth, nodule formation and nodule function in the annual burr medic, Medicago polymorpha cv. Circle Valley, were investigated in glasshouse pot experiments. Systemically‐infected plants from AMV‐infected seed produced 21% less shoot dry weight and accumulated 24% less fixed nitrogen in shoots than healthy plants when harvested 53 d after germination. At day 75, infected plants showed similar shoot dry weight losses (22%), but the quantity of nitrogen fixed fell by only 15%. At day 53, soluble sugar, starch and bacteroid concentrations in nodules were unaffected by AMV infection, but nitrogenase specific activity was decreased by 25% and soluble amino acids by 20%.

Although AMV infection resulted in no differences in the number of nodules formed in the first 11 d after germination or at any harvest thereafter, nodule mass was decreased by 23% for virus‐infected plants at day 53. However this difference disappeared by day 75. Growth of AMV‐infected plants was decreased probably because of impaired N2 fixation with nodule function affected rather than nodulation. Increased nodule mass relative to plant weight in virus‐infected plants, seen at day 75, implied some degree of compensation for the limitation in N2‐fixing capacity. ELISAs for AMV antigen indicated that nodules were active sites of virus multiplication.
Needle chlorosis in Sitka spruce following a three‐year exposure to low concentrations of ozone: changes in mineral content, pigmentation and ascorbic acid
Authors: LUCAS PETER W. , RANTANEN LEENA , MEHLHORN HORST
Published: April 2006

Two‐year‐old seedlings of Sitka spruce were exposed to 70 nl 1−1ozone or to filtered air over three successive summers in outdoor large‐scale fumigation chambers (Solardomes). Seven months after the last period of exposure to the pollutant and just prior to budburst, upper‐surface chlorisis affecting only the older needles of ozone‐exposed trees was observed. In many respects, the symptoms appeared to be similar to those characteristic of type 1 spruce damage occurring in parts of mainland Europe. Chlorophyll pigments were reduced in the ozone‐exposed older foliage, but no change in the ratio of chlorophylls to carotene was observed. The content of ascorbic acid was clearly related to the amount of foliar damage observed on the trees exposed to ozone and the largest increases were seen in those trees which were most visibly damaged. Although none of the foliage examined was deficient in any of the nutrient cations which were measured, the concentration of Mg in the older needles was significantly reduced by exposure to ozone, irrespective of damage symptoms. Exposure to ozone also resulted in increases in the ratios of K: Mg and Ca: Mg. In the older needles, leaching of Mg2−and K−by 0.5 mM H2SO4, pH 3.0, was enhanced by prior exposure to ozone, but the amounts removed were small (< 6%). It is suggested that long‐term exposure to ozone has a cumulative effect on plant tissue and that the observed chlorosis was the result of accelerated senescence.
Primary homostyly in Primula L. subgenus Sphondylia (Duby) Rupr. and the evolution of distyly in Primula
Authors: AL WADI HUSSEN , RICHARDS A. J.
Published: April 2006

We have studied eight species classified within Primula L. subgenus Sphondylia (Duby) Rupr. Two have monomorphic flowers and four have typically distylous flowers. P. floribunda Wall, includes both monomorphic and distylous races, while P. boveana Decres. has an incompletely discontinuous dimorphism for style length and pollen size, but is monomorphic for anther position. All the species have been tested and they are fully self‐fertile.

Evidence suggests that dimorphisms for style length (G/g), pollen size (P/p) and anther position (A/a) are each under independent genetic control. In the monomorphic P. verticillata, variations in stigma papilla length and style cell length appear to result from developmental correlates with style‐length variation. Both the monomorphic species show some continuous variation for herkogamy.

Several of the species studied show an incomplete development of the full distylous syndrome typical of most Primula species. If it is assumed that these represent evolutionary stages in the development of the full syndrome, and if it is assumed that diallelic incompatibility evolved after the evolution of distyly, then it would appear that the components of the distyly linkage group are likely to have evolved from a non‐herkogamous ancestor in the following order: (i) short style mutant G; (ii) small pollen mutant p; (iii) low anther position mutant a.
Effect of wounding on the relations between vascular rays and vessels in Melia azedarach L.
Authors: LEV‐YADUN SIMCHA , ALONI RONI
Published: April 2006

The axial and radial derivatives of the cambium showed contrasting wound responses in Melia azedarach L. The vascular rays became larger, less spaced, and their shapes were modified following wounding. As the wound effects vanished with time, ray size, spacing and shape returned to normal patterns. On the other hand, following wounding, vessels became smaller, and fibres were not formed. Vessels returned to normal size, and vessels and fibres reverted to their normal pattern when wound effects vanished. These changes in the patterns of vascular rays, vessels and fibres reflect the nature of the regulatory mechanisms of their formation: axial signal flows, and the involvement of wound effects.
Species‐dependent patterns of fructan synthesis by enzymes from excised leaves of oat, wheat, barley and timothy
Authors: CAIRNS ANDREW J. , ASHTON JENNIFER E.
Published: April 2006

Excised leaves of oat, wheat, barley and timothy were illuminated continuously for 24 h and shown to accumulate both sucrose and fructan. The fructan complements of the four species were compared with the well‐characterized pattern from leaves of L. temulentum L. by thin‐layer chromatography (TLC). Wheat and barley had similar patterns of oligosaccharides, accumulating isokestose, kestose and a range of oligofructans up to an apparent degree of polymerization (DP) of 10. Oat leaves accumulated neokestose in addition to kestose and isokestose. The oligofructans of oat also extended up to DP 10, though the pattern was more complex than that of wheat and barley. Timothy leaves accumulated fructan predominantly of apparent DP ≤ 16 and little smaller oligofructan. Analysis of concentrated carbohydrate extracts showed isokestose, kestose and a ladder of oligofructans of apparent DP in the range 4 to ≤ 20 in induced timothy leaves. The results showed that leaves of each grass accumulated a distinct and species‐specific pattern of fructan.

Concentrated enzyme preparations from illuminated leaves of each species were incubated at 30 °C with 400 mol m−3 sucrose at pH 4.6 in the presence of 16 mol m−3 pyridoxal hydrochloride. The preparations catalyzed the de novo net synthesis of trisaccharides and larger oligofructans at rates approximating to rates of soluble carbohydrate accumulation in the tissue. On TLC, the enzyme products exhibited a marked resemblance to the complement of native fructan in the source tissue. The data demonstrate that the species specificity of the fructan complement can be explained by the properties of synthetic enzyme(s) alone, and is not dependent upon structural features of intact cells or tissues.

The established view of fructan synthesis holds that the polymerizing enzyme, fructan: fructan fructosyl transferase (FFT), is inhibited by sucrose. The enzymes from all five grass species manufactured fructans of DP ≤ 3 in the presence of high concentrations of sucrose (above 200 mol m−3). Hence the properties of these grass fructan polymerases differ from those of FFT.
Binding of monoclonal antibodies to vegetative tissue and fucose‐containing polysaccharides of Fucus serratus L.
Authors: GREEN JONATHAN R. , STAFFORD CHRISTOPHER J. , JONES J. LEIGHTON , WRIGHT PHILIP J. , CALLOW JAMES A.
Published: April 2006

Monoclonal antibodies (MAbs FS1–FS12) have previously been used to study the organization of cell surface glycoproteins on sperm and eggs of the brown alga Fucus serratus L. These antibodies were raised against Fucus sperm, but three (FS2, FS4 and FS5) also bind to the egg cell surface, and one (FS9) binds internally to polyphenol bodies in the egg. Evidence from immunofluorescence studies with the MAbs, using confocal laser scanning microscopy, has shown that the glycoproteins on the surfaces of both sperm and eggs are organized into domains. In the present study, the full set of MAbs was tested for cross‐reaction with F. serratus vegetative tissue in order to make a comparison with the gamete cell surfaces and to see whether any of the MAbs localized to particular regions of the mature thallus. A new MAb, FS13, which was raised to Fucus egg antigens, has also been characterized and used in this study. The results of ELISA, dot blot assays and indirect immunofluorescence tests show that the four MAbs which cross react with eggs (FS2, FS4, FS5 and FS9) also bind to vegetative tissue. Three MAbs (FS1, FS7 and FS12) bind to sperm and vegetative tissue, and MAbs FS3, FS6, FS8, FS10 and FS11 bind specifically to sperm. FS13 binds to egg vesicles and to vegetative tissue, but not to sperm. Western blotting and inhibition assays using ELISA have shown that the antigens recognized by the MAbs in vegetative tissue are different from those recognized on gametes, and glycoproteins on the latter are specific to each cell type (i.e. sperm or egg). Only FS7 and FS12 of the cross‐reacting MAbs recognize glycoproteins in vegetative tissue. They bind to most cell types, as does FS9 which recognizes polyphenols. The MAbs FS2, FS4, FS5 and FS13 all recognize fucose‐containing polysaccharides in vegetative tissue; however they recognize different epitopes and localize to different regions of the thallus. It is possible to distinguish between the amorphous matrix in the medulla which is FS13+, the mucilage at the plant surface which is FS2/5+ and the mucilage plug in the ostiole which is FS4+ FS2/5+. In addition FS13 and FS2/5 also label the walls of cells in the medulla. The results are compared with previous findings on the localization of fucoidan and ascophyllan in Fucus tissue.
Interphase and preprophase microtubule organization in some polarized cell types of the liverwort Marchantia paleacea Bert.
Authors: APOSTOLAKOS P. , GALATIS B.
Published: April 2006

The organization of interphase and preprophase‐prophase microtubules was studied in photosynthetic filament mother cells (PFMCs), photosynthetic filament cells (PFCs), mucilage papilla mother cells (MPMCs) and mucilage papillae (MP) of Marchantia paleacea Bert. These cell types exhibit polarized growth resulting, (a) in the formation of cell outgrowths followed by asymmetrical division (PFMCs and MPMCs), or (b) in the development of a tubular cell shape (PFCs and MP). The above cell types display an interphase cortical microtubule ring perpendicular to the axis of growth. In PFMCs and MPMCs it resides at the base of the cell outgrowth, while in PFCs and MP it has a median location. This microtubule ring is involved in the deposition of transverse, circumferentially aligned, cellulose microfibrils, defines the site where cell protrusion formation occurs and affects cell morphogenesis. In differentiated MP microtubules are rearranged in longitudinal or oblique cortical arrays. PFCs and MP also contain a prominent system of endoplasmic microtubules which may be involved in cytoplasmic polarization. In PFMCs, PFCs and MPMCs the interphase microtubule ring seems to function as a preprophase microtubule band (PPB). In the asymmetrically dividing PFMCs and MPMCs the PPB is complete but in symmetrically dividing PFCs it may be interrupted. The cell plate meets the parent wall at sites adjacent to the PPB cortical zone. These observations reveal further peculiarities in cortical microtubule organization and particularly in the PPBs of M. paleacea. Possible factors underlying the formation of complete or interrupted PPBs are discussed.
Impact of O3 and SO2 on reproductive development in oilseed rape (Brassica napus L.). I. Pollen germination and pollen tube growth
Authors: BOSAC C. , BLACK V. J. , BLACK C. R. , ROBERTS J. A. , LOCKWOOD F.
Published: April 2006

A single exposure of pollen of Brassica napus L. cvs Tapidor or Libravo to 100 nl l−1 ozone (O3) either in vitro or in vivo on the anthers of intact plants had no significant effect on either pollen germination or pollen tube growth. Exposure of dry pollen to 200 nl l−1 sulphur dioxide (SO2) also produced no significant effect. However, pollen germination was significantly reduced and pollen tube growth impaired in both cultivars when pollen was exposed in unbuffered incubation medium to 200 nl l−1 SO2. The pH of the unbuffered medium fell from 6.5 to 5.5 during fumigation, suggesting a role for acidification in the observed SO2‐induced effects. This view is supported by evidence that percentage germination decreased linearly with pH in culture media buffered to provide pH values ranging from 6.05 to 3.0. Pollen tube growth was also impaired at pHs of 5.6 and below. The significance of pollutant‐induced impairment of pollen germination and growth for reproductive development and the influence of moisture in modifying the impact of SO2 and O3 are discussed.
Effects of acid, or ammonium‐enriched, artificial mist on leaf blight of London plane [Platanus×acerifolia (Ait.) Willd.] and on the behaviour of the causal fungus, Apiognomonia veneta (Sacc. & Speg.) Höhn.
Authors: SURY ROMAN VON , FLÜCKIGER WALTER
Published: April 2006

Three types of artificial mist (acid = A, pH 3.0, 1400 μequiv. total ionic strength l−1; NH4+‐enriched = N, pH 5.4, 1400 μequiv. l−1; and control = C, pH 4.9–5.1, 10–15 μequiv. l−1) were used to detect the effects of wet deposition on the fungus Apiognomonia veneta (Sacc. & Speg.) Höhn. and on the susceptibility of its host tree, the London plane [Platanus×acerifolia (Ait.) Willd.], to leaf blight or anthracnose. On a nutrient‐poor agar, germination of conidia of A. veneta was strongly inhibited by mist A. Germination in mists N and C was higher, being 22 and 25 %, respectively. In autumn and spring, London plane seedlings were sprayed 15 times with each of mists A, N or C. Thereafter, leaves were inoculated with conidia. At this time, the pH of all leaf surfaces was similar. Inoculation in spring led to typical leaf blight symptoms. However, infection was light and no significant differences in symptom development were detected between mist treatments. After the C pre‐treatment, the germination of conidia was significantly inhibited on leaf surfaces, and in leaf washings, when compared with the A and N pre‐treatments. More spores germinated in a water blank than in leachates from C‐misted trees. A fungistatic, phenolic compound was found in leachates and isolated by TLC. It is suggested that this compound was involved in the inhibitory effect of the leaves treated with a control mist, but was removed or inactivated by mist A and N. We conclude that constitutive resistance of London plane leaves is affected adversely by acid and/or nutrient‐enriched mist.
Effects of pH on arbuscular mycorrhiza I. Field observations on the long‐term liming experiments at Rothamsted and Woburn
Authors: WANG G. M. , STRIBLEY D. P. , TINKER P. B. , WALKER C.
Published: April 2006

The percentage colonization of roots by arbuscular mycorrhizal fungi was measured in the field in two crops of spring oats (Avena sativa L.) and one of maincrop potatoes (Solanum tuberosum L.), successively grown over a period of 3 yr on the long‐term liming experiments at Rothamsted and Woburn. In both crops, all years, both phosphorus treatments and at both sites, percentage colonization was little affected by soil pH from over a range approximately 4.5 to 7.5. There was little effect of pH on crop yields. Up to nine species of coarse endophyte could be identified from spores (≤ 50 μm diameter) in plots of pH 5.5 and above. There were markedly fewer spores at (approximately) pH 5.5 and none in the most acid plots.
Symbiotic exchange of carbon and phosphorus between cucumber and three arbuscular mycorrhizal fungi
Authors: PEARSON J. N. , JAKOBSEN I.
Published: April 2006

Cucumber (Cucumis sativus L.) was grown in an irradiated soil:sand mixture in PVC tubes containing a root compartment, a hyphal compartment and a hyphal 32P‐labelling compartment. The soil was inoculated with either Scutellospora calospora (Nicol. & Gerd.) Walker & Sanders, Glomus sp. or Glomus caledonium (Nicol. & Gerd.) Trappe & Gerdemann or left uninoculated.

At 23 d from sowing 20 μCi of an aqueous solution of carrier‐free 32P was pipetted into the hyphal labelling compartment. Just 24 h later the plants were labelled with 14CO2 for 16 h. At harvest the plants were analysed for mycorrhizal colonization and distribution of 14C and 32P.

Hyphae of G. caledonium proved to have the most rapid 32P uptake and transfer system of the three fungi studied. The host was provided with an order of magnitude more 32P than supplied by either Glomus sp. or S. calospora. The S. calospora‐colonized plants contained the least 32P counts of the three mycorrhizal treatments. 75% of the total 32P in the plant was present in the shoots of the plants colonized by G. caledonium; the corresponding figures for the shoots of S. calospora and Glomus sp. were 45 and 25%, respectively.

The proportion of assimilated 14C allocated to below‐ground events was 35, 32 and 25 with S. calospora, Glomus sp. and G. caledonium, respectively. The specific incorporation of 14C into roots colonized by Glomus sp. was 1.8 and 3.1 times as high as into roots colonized by G. caledonium and S. calospora, respectively.

In contrast, the specific root respiration (Bq mg−1 d. wt) was similar in the mycorrhizal treatments. The 14C flow into external hyphae was approximately 0.8% of the total assimilated 14C for all three fungi.

Based on these results, mycorrhizal efficiency was calculated as hyphal 14C use per unit 32P transported, below‐ground 14C use per unit 32P transported, 32P transported per metre of hyphae and hyphal 14C use per metre of hyphae.
Nomenclature and diagrammatic representation of oligomeric fructans — a paper for discussion
Authors: LEWIS D. H.
Published: April 2006

As proposed at the Second International Symposium on Fructan, a paper for discussion has been prepared which suggests alternative schemes based on that by A. L. Waterhouse circulated at the Symposium. This scheme has itself been modified in collaboration with N. J. Chatterton and published together with a glossary of terms. This glossary, also slightly modified, is reproduced here. The principal alternative (and additional) proposals have been made by N. C. Carpita, C. J. Pollock and D. H. Lewis, and compiled and edited by the last of this trio.
Influence of acidic mist on frost hardiness and nutrient concentrations in red spruce seedlings
Authors: SHEPPARD LUCY J. , CAPE J. N. , LEITH I. D.
Published: April 2006

Two‐year‐old red spruce (Picea rubensSarg.) was grown in replicated open‐top chambers supplied with charcoal‐filtered air near Edinburgh, Scotland. Between May and November 1989, plants were exposed to four mist treatments, three containing sulphuric acid and ammonium nitrate in equimolar concentrations at 0.005 mol m−3(pH 5) or 1.0 mol m−3(pH 27), and a fourth treatment with sulphuric acid alone at 1.0 mol m3(equivalent to 2 mm precipitation). Two dose rates were used for the pH 2.7 treatment equivalent to 2 and 8 mm of rain per week. Three subtreatments (soil surface exposed to mist, addition of extra sulphuric acid to the soil surface, exclusion of mist from the soil) were included in each chamber. Frost hardiness was assessed by measuring rates of electrolyte leakage after controlled freezing of detached shoots.

At the end of October, frost hardiness, expressed as the lethal temperature for 50% of shoots (LT50), was decreased by 8 °C in the 8 mm wk−1treatment at pH 27, compared to pH 5. The 2 mm wk−1treatment at pH 2.7 had no effect on frost hardiness either when ammonium nitrate was present or absent (i.e. sulphuric acid only). Excluding mist from the soil, and adding extra sulphuric acid, bothincreasedfrost hardiness by about 3 °C when compared with uncovered soil. Excluding mist from the soil increased the amount of foliage initiated and produced inside the chambers but neither subtreatment, excluding the mist nor providing additional sulphuric acid to the soil affected foliar nutrient concentrations. Mist of pH 27 as sulphuric acid alone and in combination with ammonium nitrate both enhanced N uptake.

Several observations concerning the effect of acidic mist on frost hardiness were confirmed by this study: (i) preventing mist from reaching the soil/roots, improving conditions for root growth can ameliorate the effects of acidic mist on shoot growth and frost hardiness; (ii) the effect was determined by the ion dose but not by the ion concentration in the mist; (iii) the effect was primarily mediated through foliar absorption; (iv) the presence of high foliar nitrogen concentrations did not increase frost hardiness when foliar sulphur concentrations were also high; (v) low N concentrations were more important for frost hardiness than high foliar N concentrations.
Light environment alters response to ozone stress in seedlings of Acer saccharum Marsh, and hybrid Populus L.
Authors: TJOELKER M. G. , VOLIN J. C. , OLEKSYN J. , REICH P. B.
Published: April 2006

Hybrid poplar (Populus tristis Fisch. ×P. balsamifera L., cv. Tristis) and sugar maple (Acer saccharum Marsh.) seedlings were grown under contrasting light and ozone treatments to investigate the role of the light environment in their response to chronic ozone stress. In consecutive growth chamber experiments, cuttings of shade‐intolerant poplar and 3‐yr‐old seedlings of shade‐tolerant sugar maple were grown in pots for 6 and 10 wk, respectively, under shaded, low light irradiance (c. 2.5 mol m−2 d−1 PPFD or 7% of full sunlight) and six‐fold greater irradiance (c. 16.6 mol m−2 d−1 PPFD or 45% of full sunlight) in combination with low (< 10 nl 1−1) and elevated levels of ozone (c. 99–115 nl 1−1). In unshaded poplar plants, ozone exposure reduced root dry mass by 33% at final harvest, while shaded plants had no such response. By comparison, sugar maple root dry mass was reduced by ozone in shaded plants by 10%, but was unaffected by ozone in unshaded plants. In poplar, leaf area: plant dry mass ratios were unaffected by ozone, whereas in sugar maple ozone‐exposed plants had a 24% lower leaf area: plant dry mass ratio in the shaded treatment. In shade‐grown sugar maple, ozone doubled dark respiration rates of leaves, but in unshaded seedlings ozone had no effect on respiration. In comparison, in poplar plants ozone exposure resulted in greater increases in dark respiration under unshaded than shaded conditions. In unshaded plants, ozone treatment resulted in lower in situ net photosynthesis in poplar, but not in sugar maple. Overall, shade‐grown sugar maple appeared more sensitive to ozone stress than unshaded plants in terms of lower leaf area: plant dry mass ratio and root growth and higher leaf respiration. In poplar on the other hand, root growth, leaf respiration and photosynthesis were more affected by ozone in unshaded than in shaded plants. These findings suggest that shade‐grown sugar maple and unshaded poplar may experience greater reductions in carbon gain and growth under elevated levels of ozone than plants under the opposite light conditions.
Light environment alters response to ozone stress in seedlings ofAcer saccharumMarsh, and hybridPopulusL.
Authors: VOLIN J. C. , TJOELKER M. G. , OLEKSYN J. , REICH P. B.
Published: April 2006

Diagnostic gas exchange measurements and foliar chemical assays were conducted on hybrid poplar (Populus tristisFisch. ×P. balsamiferaL. cv. Tristis) and sugar maple (Acer saccharumMarsh.) seedlings grown under contrasting light and ozone treatments. Seedlings were grown in low irradiance (c. 2.5 mol m−2d−1) and six‐fold greater irradiance (c. 16.6 mol m−2d−1) in combination with low (< 10 nl I−l) and elevated (99–115 nl 1−1) ozone. Analysis of light response curves showed ozone‐induced reductions in photosynthetic capacity and quantum yield for unshaded poplar and shaded sugar maple, but not the contrasting light treatments. Photosynthesis at saturating CO2concentrations was decreased in the elevated ozone treatment in both the unshaded and shaded poplar and in shaded sugar maple. Poplar had significant reductions in chlorophyll concentration due to ozone exposure in both unshaded and shaded treatments. Older leaves of unshaded poplar plants had significantly greater reductions in chlorophyll levels due to ozone than older leaves of shaded plants. In maple, only shade‐grown leaves had significant decreases in chlorophyll concentration due to ozone exposure. The diagnostic gas exchange measurements in conjunction with chlorophyll measurements indicate that in hybrid poplar, unshaded leaves may be more sensitive to ozone than shade leaves, while in sugar maple, shade leaves are more sensitive to ozone. For hybrid poplar a decrease in photosynthetic capacity, quantum yield and chlorophyll concentration in the unshaded, moderately high light environment due to elevated ozone is consistent with prior studies. The results indicating that sugar maple seedlings may be more detrimentally affected by elevated ozone in the lower light environment may have serious implications for this and other shade‐adapted species with respect to their performance in an understorey environment.
Light environment alters response to ozone stress in seedlings of Acer saccharum Marsh, and hybrid Populus L.
Authors: LINDROTH R. L. , REICH P. B. , TJOELKER M. G. , VOLIN J. C. , OLEKSYN J.
Published: April 2006

Both light conditions and ozone fumigation alter the chemical composition of tree foliage and are thus likely to influence tree‐insect interactions. We investigated the direct and interactive effects of light environment and ozone exposure on the performance of gypsy moth (Lymantria dispar L.) larvae reared on hybrid poplar (Populus tristis Fisch. ×P. balsamifera L. cv. Tristis) and sugar maple (Acer saccharum Marsh). We used a split‐plot experimental design (light nested within ozone) and fourth‐instar bioassays to calculate standard indices of insect growth and feeding performance. For insects fed poplar, consumption, growth and processing efficiencies were affected more by light environment than by ozone. Larvae ate and grew less on high‐light foliage, responses attributable to higher levels of phenolic glycosides in those leaves. For insects fed maple, no significant effects of light, ozone, or light x ozone were observed. These results demonstrate that light environment and ozone pollution can alter the dynamics of interactions between trees and associated insects and that responses are species‐specific.