bluuebunny/crossref_metadata_2025 huggingface dataset:
Atmospheric nitrogenous compounds and ozone – is NOx fixation by plants a possible solution?
Authors: WELLBURN ALAN R.
Published: March 2003

Air quality thresholds for O3 for the protection of human health and vegetation set by the European Union (EU) have been exceeded in Europe regularly in the 1990s. Because target reductions for oxides of nitrogen (NOx) set for the year 2000 are unlikely to be achieved, these O3 exceedances are likely to continue into the next millenium. Improvements of plant tolerance towards O3 are being investigated but very little work has been done to explore NOx tolerance and plant acclimation to NO2 and NO. However, it is clear that within the populations of some plant species there is wide variation, and some individuals can fix NOx and use the nitrogen directly from the atmosphere, rather than rely upon, for example, root uptake of nitrate. It is possible that individuals capable of fixing NOx could be selected for a range of species, and genotypes with high rates of uptake could be of value as crops or for forestation in polluted areas (e.g. landscaping in the vicinity of motorways) to reduce tropospheric concentrations of NOx significantly and also to decrease the potential for O3 production.
Ecotype differentiation and coexistence of two parapatric tetraploid subspecies of cocksfoot (Dactylis glomerata) in the Alps
Authors: GAUTHIER P. , LUMARET R. , BÉDÉCARRATS A.
Published: March 2003

Two tetraploid subspecies of Dactylis glomerata L., subsp. reichenbachii (Hausm.) Stebbins et Zohary and subsp. glomerata, occur in the French Alps. The former is confined to dolomitic, south‐facing, alpine lawns above 2000 m, whereas the latter occurs in non‐dolomitic habitats in subalpine meadows mainly below 1900 m. Previous studies of allozyme variation have shown that genetic introgression between the two subspecies occurs over large areas. By contrast, morphologically intermediate individuals only occur in an extremely narrow area, suggesting that the morphological and physiological differences between the two subspecies is of adaptive significance. A reciprocal clone transplant experiment was set up to examine (1) any genetic differences between subspecies indicative of ecotypic differentiation in relation to habitat characteristics and (2) the level of phenotypic plasticity in the two subspecies. Genetic differentiation was confirmed by a statistically significant taxon × site interaction effect in anova for all traits studied. The glomerata populations produced more tillers, longer leaves and higher culms in all sites, especially in their home environment. However, reichenbachii populations produced more seeds than the glomerata populations in the original reichenbachii environment, suggesting ecotypic differentiation between the two subspecies. This result might also explain why the glomerata subspecies is unable to colonize dolomitic habitats occupied by the reichenbachii subspecies. The reichenbachii populations showed less plasticity than the glomerata populations for leaf length and floriferous tiller number, a result which is discussed in the context of the response of plants from productive and non‐productive habitats to environmental variation.
Mathematical modelling of morphogenesis in fungi: spatial organization of the gravitropic response in the mushroom stem of Coprinus cinereus
Authors: MEŠKAUSKAS A. , MOORE DAVID , FRAZER LILYANN NOVAK
Published: March 2003

The purpose of this work was to establish how the distribution of local curvatures changed during the mushroom stem gravitropic reaction and to suggest a suitable mathematical model based on these new data.

The gravitropic bending of base‐ and apex‐pinned Coprinus cinereus (Fries) S. F. Gray stems was recorded on videotapes. The images were captured from the tapes after each 10 min, rotated by 45° and transformed into tables of changing co‐ordinates of points for each stem. The non‐linear regression of these points was performed using Legendre polynomials. From the resulting equations the patterns of changing local curvature for 50 subsections per stem during 400 min of gravitropic reaction were calculated.

It was observed that base‐pinned stems first bent from the apex, but later the curvature of this part decreased, and in the late stages the apex became nearly completely straight again. Subsections, located about one third of stem length from the base determined the main part of the final curvature. The free basal part of the apex‐pinned stems bent upward and after a certain bending time also began to straighten. However, this process started significantly later and was weaker. Bending of the subsections close to the pinned apex did not stop when they reached the vertical position, and the final angle of gravitropic curvature could exceed 180°.

Plotting various functions of local bending speed and its derivatives against each other and against local angle indicated that, if the hypothetical signal about reorientation arises in the apex, its propagation towards the base did not follow simple wave or simple diffusion laws. The importance of the local angle of all subsections both for signal origin and transmission was established and a signal transmission equation, involving local angle of each subsection, was derived. After creating a suitable program this partial differential equation was solved numerically. The generated shapes of the bending stem coincided in high degree with experimentally observed images.
Solute transport into healthy and powdery mildew‐infected leaves of pea and uptake by powdery mildew mycelium
Authors: CLARK JOANNA I. M. , HALL J. L.
Published: March 2003

The transport of sugars and amino acids into the mycelium of Erysiphe pisi DC. was investigated using two different systems, intact leaf discs and mycelial suspensions. Of the sugars tested, glucose was preferentially taken up by both uninfected and mildew‐infected leaf discs, whereas glutamine was taken up by both tissues at a higher rate than lysine or aspartic acid. Leaf discs from infected tissue had a greater uptake capacity than those from healthy tissue for both sugars and amino acids. The uptake of glucose was inhibited more markedly than that of sucrose and fructose by 10 μm carbonyl cyanide m‐chlorophenylhydrazone (CCCP), 1 mmN‐ethylmaleimide (NEM), 1 mm diethyl pyrocarbonate (DEPC) and 1 mm phenylglyoxal, whereas 1 mm PCMBS (p‐chloro‐mercuribenzenesulphonic acid) inhibited sucrose uptake to the greatest extent. Uptake of glutamine, lysine and aspartic acid was inhibited similarly by CCCP (80%), NEM (20%), DEPC (70%) and PCMBS (60%). Additionally, leaf discs were used to determine which solutes could be taken up from leaf tissue by the fungus. The uptake of sugars into the mycelium was greater than that of amino acids.

Suspensions of powdery mildew mycelium accumulated glucose at about three times the rate of sucrose or fructose, and the amino acid glutamine was taken up at three times the rate of lysine or aspartic acid. Spores separated from the suspension had a low uptake capacity.

When the reducing sugar concentration of leaf apoplastic fluid was estimated, leaves infected by powdery mildew had much higher amounts in the apoplast, whereas the activity of acid invertase also appeared to be higher in apoplastic fluids from infected leaves. When apoplastic fluid samples were run on SDS gels, an invertase antibody detected two bands in samples from infected tissues that were not found in the uninfected samples.
Long‐term exposure to enhanced ultraviolet‐B radiation in the sub‐arctic does not cause oxidative stress in Vaccinium myrtillus
Authors: TAULAVUORI E. , BÄCKMAN M. , TAULAVUORI K. , GWYNN‐JONES D. , JOHANSON U. , LAINE K. , CALLAGHAN T. , SONESSON M. , BJÖRN L. O.
Published: March 2003

The aim of this work was to assess whether or not oxidative stress had developed in a dwarf shrub bilberry (Vaccinium myrtillus L.) under long‐term exposure to enhanced levels of ultraviolet‐B (u.v.‐B) radiation. The bilberry plants were exposed to increased u.v.‐B representing a 15% stratospheric ozone depletion for seven full growing seasons (1991–1997) at Abisko, Swedish Lapland (68°N). The oxidative stress was assessed on leaves and stems by analysing ascorbate and glutathione concentrations, and activities of the closely related enzymes ascorbate peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2). The affects of autumnal leaf senescence and stem cold hardening on these variables were also considered. The results showed that the treatment caused scarcely any response in the studied variables, indicating that u.v.‐B flux representing a 15% ozone depletion under clear sky conditions is not sufficient to cause oxidative stress in the bilberry. It is suggested that no strain was evoked since adaptation was possible under such u.v.‐B increases. The studied variables did, however, respond significantly to leaf senescence and especially to stem cold hardening.
Iron accumulation in root apoplasm of dicotyledonous and graminaceous species grown on calcareous soil
Authors: ZHANG XIKE , YI CUILING , ZHANG FUSUO
Published: March 2003

Solution culture studies have demonstrated that apoplasmic iron (Fe) deposited in the roots of dicotyledonous and graminaceous plants can be mobilized to improve plant iron status in conditions of limited Fe supply. The present study investigated the formation of the apoplasmic Fe pool in dicotyledonous (soybean and cucumber) and graminaceous (wheat) plants in a pot experiment. The pots had three compartments such that plants could take up Fe and other nutrients from two calcareous soils treated with different Fe forms without their roots touching with soil directly. In this way overestimating Fe accumulation in root apoplasm was avoided. The results showed that while the root d.wt of wheat did not vary when soils were supplied with different Fe resources, the root d. wt of soybean and cucumber supplied with FeEDTA decreased compared with the control (without Fe treatment). Supplying FeEDTA in the side compartment increased shoot d. wt and Fe concentration in shoots of all species. However, supplying Fe(OH)3 had no effect on shoot d. wt or Fe concentration in the shoots of any species. Soybean and cucumber accumulated little or no Fe in the root apoplasm in controls or in Fe(OH)3 treatments. By contrast, a large amount of Fe was deposited in the root apoplasm of wheat grown in similar conditions. Remarkably, when FeEDTA was supplied in the soils, large apoplasmic iron pools were formed in the roots of all three species. Therefore, in dicotyledonous plants grown on calcareous soils, little or no apoplasmic iron pool forms, because there is not enough available Fe in the soil solution and the plants have little ability to mobilize Fe3+ in the soil. By contrast, a larger apoplasmic iron pool could form in graminaceous plants at lower concentrations of available soil‐Fe possibly by enhancing the release of phytosiderophores which could mobilize Fe3+ in the soil and then transfer the Fe3+‐complexes to the root apoplasm.
Differential sensitivity of nodulation to ethylene in soybean cv. Bragg and a supernodulating mutant
Authors: CABA JUAN M. , POVEDA JOSÉ L. , GRESSHOFF PETER M. , LIGERO FRANCISCO
Published: March 2003

We previously found that the ethylene inhibitor Ag+ could overcome the inhibitory effect of nitrate on nodulation of soybean (Glycine max) cv. Bragg. The same treatment increased nodulation quantitatively under non‐inhibitory conditions, strongly suggesting involvement of ethylene in the control of nodulation in this species. Supernodulation mutants that lack internal autoregulation of nodulation, however, had biosynthesis capacity similar to the wild type. In the present work, the effects of ethylene on nodulation of ‘Bragg’ and two separate, but allelic, supernodulating mutants (nts382 and nts1007) were compared. The nodulation process appeared much more sensitive than plant growth and development to ethylene, which reduced the number of nodules per plant, but nearly twofold more in the wild type than in the supernodulation mutants. The cause–effect relationship is established by the counteracting effect of Ag+ and the fact that the stronger the inhibition by ethylene, the higher the recovery of nodulation ability with the ethylene antagonist. This higher tolerance of or lower sensitivity to ethylene in nts382 persists even under low inoculum dose, where nodule number and mass could be decreased to wild‐type levels. Differences between the mutant and the wild type in the triple response test do not appear to support differences in ethylene perception on a whole‐plant basis. The results suggest that sensitivity of nodulation to ethylene might have been affected in supernodulation mutants.
Expression of chitin synthase genes in the arbuscular mycorrhizal fungus Gigaspora margarita
Authors: LANFRANCO L. , VALLINO M. , BONFANTE P.
Published: March 2003

Genomic DNA from spores of the endomycorrhizal fungus Gigaspora margarita was amplified with two sets of degenerate primers designed on conserved regions of chitin synthase polypeptides. Three chitin synthase (chs) gene portions were identified: Gimchs1, Gimchs2 and Gimchs3, encoding one class II and two class IV chitin synthases, respectively. Gimchs1 and Gimchs3 transcripts were detected by reverse transcription polymerase chain reaction (RT‐PCR) during root colonization, whereas none of three mRNAs was revealed during spore germination. The potential role of the genes expressed is discussed in the light of morphogenetic and signalling events.
Effects of increased temperature, drought and nitrogen supply on two upland perennials of contrasting functional type: Calluna vulgaris and Pteridium aquilinum
Authors: GORDON C. , WOODIN S. J. , ALEXANDER I. J. , MULLINS C. E.
Published: March 2003

Mature heather (Calluna vulgaris) and bracken (Pteridium aquilinum) turfs, transplanted from the field, were subjected to factorially combined experimental treatments for three consecutive years. Summer drought had the greatest effect, decreasing photosynthesis, growth and reproductive output in both species, and opening the bracken canopy. The timing of the drought relative to plant development was critical to which species was worst affected; bracken was worst affected by an early drought, heather by a later drought. Both species showed physiological damage during drought but, as predicted on the basis of their functional types, heather showed greater acclimation of water‐use efficiency to drought stress. Contrary to expectations based on functional types, heather responded more rapidly than bracken to increased nitrogen supply (50 kg N ha−1 yr−1). Added nitrogen caused both species to start above‐ground growth earlier in the spring. For bracken this stimulation was short‐ lived; added nitrogen might be preferentially allocated to the rhizome and the longer‐term consequences of this are unknown. For heather, nitrogen promoted growth and flowering throughout the season. There was no positive effect on the photosynthetic physiology of either species; changes in resource partitioning, and thus photosynthate production at the canopy level, are the most likely mechanism for the increase in heather shoot growth. Warmer temperatures increased heather shoot growth from early spring onwards but did not advance bracken crozier emergence, although frond height and the proportion of fertile fronds were subsequently increased. No significant effects of warming on the photosynthetic physiology of either species were found. Predictions of responses of heather and bracken to environmental change are complicated by the strong interactive effects of unpredictable climatic events such as drought and extreme winter temperatures. When drought was imposed, damage to heather was much greater in plants receiving increased nitrogen supply. Stimulation of growth by nitrogen resulted in a water demand that was unsustainable in drought conditions, leading to wilting, reduced shoot growth and some acclimation of water‐use efficiency. Additionally, a very cold winter spell proved most damaging to heather that had been droughted in the previous summer. For bracken, winter damage occurred in plants that had been warmed, with significantly fewer fronds emerging in the next spring and thus canopy photosynthetic potential being reduced. We predict that positively managed heather has the potential to limit the bracken problem in conditions of environmental change, provided that high levels of nitrogen deposition do not coincide with increased drought frequency.
Effect of competition on the responses of grasses and legumes to elevated atmospheric CO2 along a nitrogen gradient: differences between isolated plants, monocultures and multi‐species mixtures
Authors: NAVAS MARIE‐LAURE , GARNIER ERIC , AUSTIN MICHAEL P. , GIFFORD ROGER M.
Published: March 2003

The responses to CO2 of perennial grasses (Danthonia richardsonii and Phalaris aquatica) and legumes (Lotus pedunculatus and Trifolium repens) were compared under controlled conditions for isolated plants, monoculture stands and mixed‐species stands along a N gradient to test whether: plant–plant interactions between species in mixed stands changed with concentration of CO2; responses to CO2 of species in mixtures could be related to their responses as single stands; responses of mixtures to CO2 could be related to the responses of individual species to CO2 and to competition. Plants were grown for 60 d in sand, using nutrient solutions (six nitrate concentrations from 0.25 to 16 mM NO3), at ambient (c. 357 μl l−1) or elevated CO2 (c. 712 μl l−1). Species dominance in the mixtures depended more on the range of N than of CO2 concentration provided: T. repens and L. pedunculatus dominated at low concentrations of N; L. pedunculatus and P. aquatica performed better at high concentrations. Responses of species in mixtures to CO2 were related to their responses in monocultures but not to those of isolated plants. Species biomass proportions in mixtures under ambient CO2 determined the outcome of mixture responses to CO2 more than of individual species responses to CO2. These results emphasize the influence of plant–plant interactions on community responses to CO2, since mixture behaviour under elevated CO2 could not be scaled‐up from responses by isolated plants in this experiment.
The spittlebug Philaenus spumarius feeds from mature xylem at the full hydraulic tension of the transpiration stream
Authors: MALONE M. , WATSON R. , PRITCHARD J.
Published: March 2003

Feeding dynamics in the spittlebug Philaenus spumarius were analysed to determine the food source. Evidence from previous reports indicates that this species and similar insects feed from the xylem. However, it is not clear whether they extract sap from the main transpiration stream, or from some subsidiary compartment of xylem, such as immature or cavitated vessels. In feeding from such subsidiary compartments, the insects could avoid the large hydraulic tensions thought to prevail in xylem on the main transpiration stream. Philaenus, for example, is shown here to initiate feeding, and to feed rapidly, from plants in which the full xylem tension is estimated at −10 bar. From measurements of feeding rates and feeding patterns in stressed and unstressed plants, it is shown that Philaenus cannot feed from subsidiary xylem compartments. It is concluded that this insect feeds directly from the main transpiration stream, and at the full hydraulic tension which prevails there. The anatomy of the feeding pump in Philaenus appears consistent with this conclusion. Spittlebugs therefore offer an experimental tool for quasi‐ non‐invasive sampling of the transpiration stream.
Mycorrhizal colonization of Pinus muricata from resistant propagules after a stand‐replacing wildfire
Authors: BAAR J. , HORTON T. R. , KRETZER A. M. , BRUNS T. D.
Published: March 2003

Colonization of mycorrhizal fungi was studied in a Pinus muricata forest on the coast in California, USA, burned by a stand‐replacing wildfire in October 1995. Naturally established field seedlings of P. muricata were harvested 1 yr after the fire. The species composition of the mycorrhizal fungi on these field seedlings was dominated by Rhizopogon species, Wilcoxina mikolae and Tomentella sublilacina. Bioassays, set up with soil collected immediately after the fire, were used to determine which mycorrhizal species had colonized the burned area from resistant propagules. The P. muricata seedlings in these bioassays were dominated by suilloid and ascomycetous fungi, the same fungi which dominated the mycorrhizal flora of seedlings in pre‐fire bioassays derived from the same forest site, suggesting that resistant propagules were the primary inoculum source for naturally establishing seedlings. Drying of post‐fire soil for 1 month raised the number of bioassay seedlings associated with Rhizopogon olivaceotinctus, while the number of bioassay seedlings associated with Rhizopogon ochraceorubens was reduced. Fire appeared to have either stimulated or provided a competitive advantage to R. olivaceotinctus, which increased in abundance on the post‐fire bioassay and field seedlings. Soil collected from the burned area was diluted with sterile soil in three different concentrations, and the number and frequency of mycorrhizal taxa on bioassay seedlings decreased with increased dilution. Although precise quantification was not possible, propagules of the Rhizopogon species were much more abundant than those of Tomentella or Wilcoxina species. Differences between the mycorrhizal associates of bioassay seedlings, naturally regenerated seedlings, and different inoculum sources are discussed.
Helper bacteria and pathogenicity assessments
Authors: Newton A. C. , Toth I. K.
Published: March 2003

In the field, pathogens exist in a diverse and dynamic ecological environment with other organisms (Blakeman, 1993; Preece & Dickinson, 1971). We tend to assume that these other organisms are ‘benign’ or perhaps in competition with the pathogen to occupy a particular niche. However, bacteria are often observed to be in close association with pathogens, as witnessed by the difficulty of eliminating them during isolation of pathogens involved in plant diseases. We now have clear evidence (Dewey et al., pp. 489–497 in this issue) that they are sometimes neither benign, nor in competition, but actually helping the pathogen successfully infect its host even when the bacteria themselves are not pathogens of that host.
Does calcium ameliorate the negative effect of NaCl on melon root water transport by regulating aquaporin activity?
Authors: CARVAJAL MICAELA , CERDÁ ANTONIO , MARTÍNEZ VICENTE
Published: March 2003

The hydraulic conductance (L0) of detached, exuding root systems from melon (Cucumis melo cv. Amarillo oro)
was measured. All plants received a half‐strength Hoagland nutrient solution, and plants stressed either solely with
NaCl (50 mM) or with NaCl (50 mM) following treatment (2 d) with CaCl2 (10 mM) were compared with controls
and CaCl2‐treated (10 mM) plants. The L0 of NaCl‐treated plants was markedly decreased when compared to
control and CaCl2‐treated plants, but the decrease was smaller when NaCl was added to plants previously treated
with CaCl2. A similar effect was observed when the flux of Ca2+ into the xylem and the Ca2+ concentration in the
plasma membrane of the root cells were determined. In control, CaCl2‐ and NaCl + CaCl2‐treated plants, HgCl2
treatment (50 μM) caused a sharp decline in L0 to values similar to those of NaCl‐stressed roots, but L0 was
restored by treatment with 5 mM DTT. However, in NaCl roots only a slight effect of Hg2+ and DTT were
observed. The effect of all treatments on L0 was similar to that on osmotic water permeability (Pf) of individual
protoplasts isolated from roots. The results suggest that NaCl decreased the passage of water through the
membrane and roots by reducing the activity of Hg‐sensitive water channels. The ameliorative effect of Ca2+ on NaCl stress could be related to water‐channel function.
Patterns of molecular genetic variation in Plantago major and P. intermedia in relation to ozone resistance
Authors: WOLFF K. , MORGAN‐RICHARDS M. , DAVISON A. W.
Published: March 2003

Patterns of molecular genetic variation were examined in seed collections of Plantago major and Plantago
intermedia, used previously to investigate the variations in ozone (O3) resistance of these species across Europe.
Total genomic DNA was amplified with random primers (random amplied polymorphic DNA (RAPD) and inter‐
single sequence repeats (SSR)) to produce 73 genetic markers. In addition, allozyme and chloroplast variations
were surveyed. Genetic markers were examined for association with O3 resistance in 18 British populations of
P. major as well as 27 continental European populations of P. major and P. intermedia. Two populations that
exhibited increased resistance to O3 following several years' exposure to high O3 concentrations in the field showed
decreased genetic variation over time. In addition, their genetic composition showed no drastic change, which
suggests that the change in resistance to O3 was probably the result of selection on genotypes already present in
local populations (selection in situ). It appears that selection for O3 resistance may occur in independent
populations, and also may involve a number of genetically determined traits. Consequently the finding that plants
with similar degrees of O3 resistance are not closely related was not unexpected. However, the finding of an
association of several genetic markers with O3 resistance merits further investigation.
Organic acids produced by mycorrhizal Pinus sylvestris exposed to elevated aluminium and heavy metal concentrations
Authors: AHONEN‐JONNARTH ULLA , VAN HEES PATRICK A. W. , LUNDSTRÖM ULLA S. , FINLAY ROGER D.
Published: March 2003

A cultivation method was developed to enable exposure of ectomycorrhizal plants with intact extramatrical mycelium to solutions containing different concentrations of aluminium or heavy metals. Pinus sylvestris seedlings
colonized by Suillus variegatus (two isolates), Rhizopogon roseolus or Paxillus involutus (two isolates) were used.
Seedlings were transferred to Petri dishes containing glass beads and exposed to elevated concentrations of Al, Cd,
Cu, or Ni in two ways: immediately following transfer; and after allowing mycorrhizal seedlings to develop an
extraradical mycelium that colonized the interface between the upper surface of the beads and the metal‐
containing solution. Production of organic acids in mycorrhizal and non‐mycorrhizal systems was measured by
withdrawing samples from the solution and analyzing by HPLC. In most experiments, levels of oxalic acid were
significantly higher in mycorrhizal treatments than in non‐mycorrhizal controls. The measured levels of organic
acids were variable, but the results obtained suggest that production of oxalic acid is stimulated by exposure to
elevated Al in mycorrhizal seedlings colonized by S. variegatus and R. roseolus. Elevated Al concentrations also
increased oxalic acid production by non‐mycorrhizal seedlings significantly in two of four Al experiments
performed, but the measured concentrations were significantly lower than in corresponding mycorrhizal
treatments in both cases. Malonic acid was found in the culture solution of non‐mycorrhizal and P. involutus‐
colonized seedlings, but only trace amounts were found in S. variegatus or R. roseolus‐infected seedlings. Citric,
shikimic, lactic, acetic, propionic, fumaric, formic, iso‐butyric and butyric acid were found in variable
concentrations. Production of oxalic acid by seedlings colonized by S. variegatus BL or P. involutus was not
stimulated by exposure to 0.44 μM Cd or 17 μM Ni. Exposure to 0.157 mM Cu in two separate experiments using
P. involutus 87.017 and two strains of S. variegatus (BL and I59) appeared to stimulate production of oxalic acid irrespective of mycorrhizal status or species.
Does proximity to conspecific adults influence the establishment of ectomycorrhizal trees in rain forest?
Authors: NEWBERY D. M. , ALEXANDER I. J. , ROTHER J. A.
Published: March 2003

Three ectomycorrhizal legume trees, Microberlinia bisulcata, Tetraberlinia bifoliolata and T. moreliana, form
discrete groves in the southern part of Korup National Park, in southwest Cameroon and contribute c. 45–70%
of stand basal area locally in a matrix of otherwise species‐rich arbuscular mycorrhizal forest. A transplant
experiment was performed to assess the importance of ectomycorrhizal infection associated with proximity to
parents in seedling establishment of the grove‐forming species. Nonectomycorrhizal seedlings of the three species
were transplanted into plots of two forest types, one of high (HEM, within‐grove) and one of very low (LEM,
outside the grove) abundance of all three species as adult trees. For two species (T. moreliana and M. bisulcata)
there was no difference in survival over 16 months, but for the third (T. bifoliolata) survival was best in HEM
forest, and correlated with the basal area of adult trees of ectomycorrhizal species. Only one species (T. moreliana)
increased in biomass over the experimental period; the others declined. There was no effect of forest type on
overall growth of any species, but the survivors of two (T. moreliana and M. bisulcata) had heavier stems in the
HEM forest. Differences in survival and growth of transplants between the three species were in accord with the
ecology of the species as inferred from the frequency distributions of adult tree size in the forest. Seedlings became
infected with ectomycorrhizas in both forest types; where there was a difference in extent of infection (T.
moreliana) this was not related to survival or growth; and where there was a difference in survival (T. bifoliolata) this was not related to extent of infection. These results confirm that mycorrhizal inoculum associated with conspecific adults is neither a prerequisite nor a guarantee of seedling establishment, but indicates that in some circumstances there might be benefits of being close to parents. Further research is required to unravel the complexities of ectomycorrhizal community structure in this spatially and temporally heterogeneous forest, and to clarify the extent to which the various hosts share ectomycorrhizal partners.
Development and good breeding in legume models: poise and peas?
Authors: Downie J. A. , Bonfante P.
Published: March 2003

John Innes Centre, Norwich, UK, June 2000

Genomics research involving legumes, an area that is attracting major funding, has two distinct branches – work involving model species, and work involving crops. This meeting aimed to stimulate communication between these two groups. The major research areas covered included leaf, flower and seed development, establishment of symbioses, pathogen interactions and applied aspects (from the conservation of legume ecotypes to products required by the market).
Limited effect of increased atmospheric CO2concentration on ombrotrophic bog vegetation
Authors: Hoosbeek Marcel R. , Van Breemen Nico , Berendse Frank , Grosvernier Philippe , Vasander Harri , Wallén Bo
Published: March 2003

Boreal and subarctic peatlands contain 20–30% of the world’s soil organic carbon, and if growing, they constitute sinks for atmospheric CO2. We hypothesized that even in the nutrient‐poor bog environment, elevated CO2would stimulateSphagnumgrowth more than vascular plant growth, thereby improvingSphagnum’scompetitive strength and enhancing carbon (C) sequestration.

 Free‐air carbon dioxide enrichment (FACE) experiments took place on predominantly ombrotrophic peatbog‐lawns in Finland (FI), Sweden (SW), The Netherlands (NL), and Switzerland (CH).

 After 3 yr of treatment, increased CO2concentration (560 ppm on volume basis) had no significant effect onSphagnumor vascular plant biomass at either site.

 This research suggests that, just as with other nutrient‐poor ecosystems, increased atmospheric CO2concentrations will have a limited effect on bog ecosystems.
Grassland species effects on soil CO2 flux track the effects of elevated CO2 and nitrogen
Authors: Craine Joseph M. , Wedin David A. , Reich Peter B.
Published: March 2003

•  Understanding and predicting the impacts of elevated atmospheric CO2, elevated nitrogen deposition, and decreases in plant diversity require better understanding of the way in which plant species influence soil CO2 flux.

•  In experimental grassland plots where atmospheric CO2, nitrogen supply, and species composition and diversity were manipulated, species effects on soil CO2 flux during 19 sampling periods over 2 yr were determined for 16 grassland species.

•  The average effect of a species on soil CO2 flux was correlated with biomass of the species grown in monoculture, suggesting that effects of species on soil CO2 flux are related to the potential productivity of a species and total belowground C allocation. During dry, warm conditions there is a greater effect of elevated atmospheric CO2 on soil CO2 flux and during these times deeper‐rooted species contribute to soil CO2 flux more than average.

•  Although differences in responses to elevated CO2 and nitrogen among species were not great, decreases in diversity can affect belowground carbon allocation depending on the plant traits of the species that are lost from ecosystems.
Stable‐carbon isotopes and soil organic carbon in wheat under CO2 enrichment
Authors: Leavitt S. W. , Pendall E. , Paul E. A. , Brooks T. , Kimball B. A. , Pinter P. J. , Johnson H. B. , Matthias A. , Wall G. W. , LaMorte R. L.
Published: March 2003

Stable‐carbon isotopic tracers were enlisted in 1996 and 1997 wheat (Triticum aestivum) free‐air CO2 enrichment (FACE) experiments to detect entry of new C into soil organic carbon (SOC) pools. Any enhanced soil inputs might mitigate rising atmospheric CO2.

 The CO2 used to enrich FACE plots (to ambient +190 µmol mol−1) resulted in 13C‐depleted wheat relative to ambient plants and the native SOC. To trace new C in control plots C4‐plant‐derived exotic soils were placed into subplots in high‐N FACE and control treatments, and a 13CO2 gas tracer was pulsed to subplots in high‐N control replicates.

 Under high‐N, isotopic mass balance showed 6% (P = 0.003) and 5% (P = 0.04) new C in 0–15‐cm and 15–30‐cm FACE SOC, respectively, after 2 yr. Results from the C4‐soil subplots were ambiguous, but the 13CO2 tracer induced a SOC δ13C increase (P = 0.08) at 15–30 cm in control‐high N consistent with 6% new C.

 We infer c. 3% year−1 (30–40 g C m−2 yr−1) SOC turnover in surface soils at high‐N under both ambient and elevated CO2. The 13CO2‐tracer result, however, is less reliable because of lower significance, fewer replicates and heterogeneous isotopic distribution within plants.
Variation in nitrogen‐use efficiency among and within subarctic graminoids and herbs
Authors: Eckstein R. Lutz , Karlsson P. Staffan
Published: March 2003

This study addresses the question of whether a trade‐off between the annual nitrogen (N) productivity (aNP) and the mean residence time (MRT), an index of N conservation, occurs both among and within species. We hypothesized that a trade‐off between aNP and MRT observed among species might not hold within species.

 Seven perennial graminoids and herbs (including one evergreen) were subjected to two fertilizer concentrations and light intensities. The effect of these treatments was examined on plant traits determining aNP and MRT.

 Except for the evergreen Tofieldia pusilla, fertilization had an overriding effect on most variables related to the species’ nitrogen use and the response to fertilization among and within species closely matched. By contrast, shade had minor effects on plant nitrogen use. Across all species, aNP varied inversely with MRT, but within species aNP and MRT were not related.

 We suggest that there might not be a trade‐off between aNP and MRT within species because small intraspecific changes in leaf life span may not involve significant consequences for leaf morphology, photosynthesis and growth.
Compression wood has little impact on the water relations of Douglas‐fir (Pseudotsuga menziesii) seedlings despite a large effect on shoot hydraulic properties
Authors: Spicer Rachel , Gartner Barbara L.
Published: March 2003

• Compression wood has been shown to reduce stem permeability, but it is not known to what extent it affects leaf‐level processes. Here, we report whole‐plant hydraulic properties of Douglas‐fir (Pseudotsuga menziesii) seedlings induced to form varying amounts of compression wood.

• Seedlings were grown under three bending treatments to assess the impact of compression wood on hydraulic properties, including stomatal conductance (gs), above‐ground shoot conductance (Kl(abg)), and both specific and leaf area‐specific conductivity (ks and kl, respectively).

• Kl(abg) was significantly lower (50% reduction) in severely bent seedlings than in controls. Similarly, both ks and kl of the main axis were significantly reduced (by 52% and 46%, respectively) in severely bent seedlings relative to controls. Seedlings in the moderate bending treatments had ks and kl that were intermediate between controls and severe bending.

• Despite clear differences in above‐ground shoot hydraulic properties, severely bent seedlings maintained the same water potentials as controls and had similar diurnal patterns of gs. This suggests that when the entire soil–plant–atmosphere continuum is considered, even a severe reduction in stem ks caused by compression wood has little impact on leaf‐level processes.
Biochemistry and molecular biology of the late‐stage of biosynthesis of anthocyanin: lessons from Perilla frutescens as a model plant
Authors: Saito Kazuki , Yamazaki Mami
Published: March 2003

Although substantial progress has been made on the molecular genetics of anthocyanin biosynthesis, the biochemistry of some components, such as anthocyanidin synthase, are not fully understood. To explore anthocyanin formation in more detail, and in particular, the late‐stage of the biosynthetic pathway, Perilla frutescens (Labiatae) was chosen as a model plant. Two chemo‐varietal forms exist in P. frutescens, the pigmented red form and, in striking contrast, the non‐pigmented green form, which contains only a trace amount of anthocyanin in the leaves and stems. Using this plant, we investigated the biochemical characteristics of anthocyanidin synthase and two anthocyanin glycosyltransferases, and in addtion we used this plant to investigate the expression and regulation of flavonoid biosynthesis genes. P. frutescens represents a good model plant for investigating anthocyanin biosynthesis. Further exploitation of this model system will require the establishment of a suitable transformation system for P. frutescens. Future work will be directed towards further characterization of the chemo‐varietal forms and investigating their evolution from the ancestral form.

Contents

I.
Introduction
9

II.
Biosynthetic enzymes and their genes
11

III.
Regulation of gene expression and regulatory genes
19

IV.
Conclusions and future prospects
21

References
21
Consumer perception of the functional dairy food market in Northern Ireland*
Authors: Gray Jennifer
Published: March 2003

The aim of this study was to investigate consumer perception and sensory quality of functional dairy produce in Northern Ireland. Consumer awareness and perception of functional foods were investigated using a structured questionnaire (n= 93). A descriptive profiling test1 was

used to evaluate the sensory characteristics of selected margarines within the functional

dairy food sector (n= 4). The research findings indicate that the

categorical variables of gender (P< 0.001), age (P<

0.01), education level (P< 0.05) and occupation (P< 0.05) are significantly related to the level of consumer awareness to the concept of functional food. Hence, consumer awareness of functional foods is a key factor influencing future acceptance of functional produce. This study also suggests that there is a strong need for clinical trials to support the role of functional ingredients in achieving optimal health.
The impact of family life on work efficiency: a study of employed women from different occupational statuses in a metropolitan area in Turkey
Authors: Bayraktar Meltem , Salman Meryem
Published: March 2003

The objective of this research was to investigate the family life of employed women from different occupational statuses (white collar, blue collar and professionals) on their work efficiency. The data were obtained from a survey of 300 randomly selected women who work in various offices, universities and factories in Ankara. The findings suggest that women in better conditions (high education, profession, etc.) experienced less negative spillover.
US aggregate demand for clothing and shoes: effects of non‐durable expenditures, price and demographic changes
Authors: Kim Kisung
Published: March 2003

The main objective of this study was to evaluate the effects of the changes in total non‐durables expenditures, prices and US demographics on demand for different clothing categories and shoes in a time‐series framework. The basis for the demand model was the almost ideal demand system model. Demographic variables included in the model were age distribution of US population (median age and variance) and proportion of non‐white population to the total US population. The results indicate that total non‐durable expenditures and price variables are significantly related to consumers’ non‐durable budget allocations for clothing categories and shoes. The results of the study also show that, among the demographic variables examined in the study, the median age and non‐white population were significant variables affecting US aggregate non‐durable expenditure allocation on men's and boy's clothing and shoes. All the demand elasticities with respect to total expenditures, own, cross‐price and demographics were also estimated.
Comparative study of properties and acceptability of Haitian and US honey‐roasted peanuts
Authors: Hinds M.J. , Jolly C.M. , Nelson R.G. , Donis Y. , Prophete E.
Published: March 2003

A honey‐roasted peanut product, flavoured with ginger and anise, was recently developed in Haiti in an effort to increase the consumption of locally grown peanuts. The objective of this study was to compare quality and consumer acceptability of the Haiti product with a traditional US‐manufactured brand. Haitian panellists (199) evaluated colour, appearance (dry/oily), crunchiness, peanut flavour and sweetness of the products using five‐point just‐about‐right scales. Colour (Minolta chromameter), hardness (TA.XT2i texture analyser fitted with a TA42 knife blade) and moisture (Denver IR‐30 moisture analyser), lipid (ethyl ether extraction) and sugar (Dionex DX‐500 high pressure liquid chromatography system) contents of the products were also determined. The Haiti product was significantly (P < 0.05) darker brown, harder and contained more (P < 0.05) sucrose and glucose but less (P < 0.05) lipid and fructose than the US product. Panellists indicated that crunchiness, peanut flavour and sweetness of both products were just right. The US product had acceptable appearance but was rated too light (hue angle = 69.6 ± 0.70, L‐value = 58.2 ± 0.47) in colour, whereas the Haiti product appeared too dry and dark (hue angle = 62.6 ± 2.79, L‐value = 44.6 ± 2.22). The Haiti peanuts were not deskinned, and their testae may have decreased the acceptability of the product's appearance and colour. The Haiti product was significantly (P < 0.05) just right to the female panellists and to the 21‐year plus panellists from all income groups. Deskinning of the peanuts and increased oil addition during roasting may improve the acceptability of the Haiti product, especially to 14–20 year olds. Decrease in sugar content may also make the Haiti product more appealing to this age group and to male Haitians.
Government transparency: the citizen perspective and experience with food and health products policy
Authors: McGregor Sue
Published: March 2003

Citizen engagement (involvement of everyday citizens in policy decisions) is now seen as a major component of governance and policy making. Government transparency is a central tenet of citizen engagement. This study was sought by Health Canada in order to learn from citizen groups in other countries about the nature and degree of transparency related to food and health product review in their country. Health Canada anticipated learning from their experiences and perceptions so that it could increase the transparency of its own review and regulatory process. The opinions of a cross‐section of stakeholders in the United States, the European Union (especially the UK), Australia and New Zealand, solicited via an e‐mail survey, were analysed. The results clearly indicate that, in general, respondents do not feel that their food and health product review system is transparent. These opinions varied depending on which of the seven dimensions of transparency was being examined. Of the 64 recommendations tendered for increasing government transparency, the 32 suggestions for improving their own systems were quite different from the 32 made for Health Canada to consider. Collectively, they provide rich insights into the refinement and clarification of the food and health product review process.
Behaviour of pesticides lindane and methyl parathion during manufacture, ripening and storage of feta cheese
Authors: Mallatou H , Pappas C P , Albanis T A
Published: March 2003

The behaviour of the pesticides lindane and methyl parathion during the manufacture, ripening and storage of feta cheese was investigated. Pasteurization of milk at 63–65°C for 30 min did not affect the concentrations of either pesticide. Lindane and methyl parathion at concentrations of 0.10 mg/kg and 16.66 mg/kg of milk, respectively, did not affect the activity of the starter culture. The concentration of lindane in the cheese and in whey/brine did not change significantly during ripening (up to 240 days). The concentration of methyl parathion in the cheese increased progressively up to 120 days of ageing, but decreased significantly (P < 0.05) from 120 up to 240 days. Methyl parathion might be bound to casein, in particular to the seryl and phosphoseryl groups of casein. Changes of brine to decontaminate the feta cheese from methyl parathion and lindane residues did not affect their concentrations in the cheese.
Influence of drier inlet temperature during pilot‐scale manufacture of rennet casein on the hydration behaviour of the rennet casein in disodium orthophosphate solution
Authors: O'Sullivan Michele M , Singh Harjinder , Munro Peter A , Mulvihill Daniel M
Published: March 2003

Rennet casein curds were dried in a pilot‐scale fluidized bed drier at air‐inlet temperatures of 80, 90, 110, 120 or 140°C. As the drier air‐inlet temperature was increased, there was a significant increase in hydration time and a significant decrease in hydrated viscosity and viscosity stability following hydration of the dried rennet caseins in 0.4% (w/w) disodium orthophosphate (DSP). The influence of air‐inlet temperature during drying on composition, the extent of Maillard reaction, the resolution of the proteins on urea–polyacrylamide gel electrophoresis (PAGE) and cation‐exchange fast protein liquid chromatography (FPLC), the dialysability of calcium and phosphorous from a 6 murea dispersion at pH 4.6, and the particle‐size parameters of milled rennet caseins were determined. Relationships between all these latter parameters and the hydration behaviours of the rennet caseins in DSP solution were also studied. Results suggest that the increase in drier air‐inlet temperature resulted in a reduction in the mean particle size of milled casein, which was significantly correlated to the changes in hydration behaviour. Hydration times increased significantly and hydrated viscosities decreased significantly with increasing levels of fluorescent Maillard reaction products (MRPs) and with increasing levels of nondialysable calcium and phosphorous in the caseins. It appears that the increase in air‐inlet temperature during drying reduced the solubility of colloidal calcium phosphate (CCP), possibly through binding of CCP to the increased levels of MRPs. This change in CCP solubility led to increased difficulty in sequestering CCP from the curd when the pilot‐scale rennet caseins were dispersed in the DSP solution, leading to the changes in hydration behaviour.