bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of exposure to ozone at different stages in the development of Plantago major L. on chlorophyll fluorescence and gas exchange
Authors: REILING K. , DAVISON A. W. 
Published: April 2006

summarySimilar ozone treatments were applied at different stages of growth to a population of Plantago major L., which is as sensitive to ozone as Bel‐W3 tobacco. Plants were grown from seed for 8 wk in controlled‐environment chambers and exposed to 70 μl O3 l−1 7 h d−1 for the whole period or for 2‐wk episodes during weeks 1 + 2, 3 + 4, 5 + 6 or 7 + 8. Controls had charcoal‐filtered air. Effects on stomatal conductance, chlorophyll fluorescence and net photosynthesis are described.The fluorescence character, t1/2, proved to be very sensitive to ozone, and it responded at all stages of plant development, but the ratio of variable to maximum fluorescence decreased only when plants received ozone during the first 2 wk of growth. The reduction was caused by a drop in maximum fluorescence. Ozone had no effect on F0.Whenever exposure occurred, O3 significantly reduced net CO2 assimilation and increased stomatal conductance. Unlike t1/2, the effects were persistent, affecting leaves that were in bud or enshrouded by leaves when the exposure occurred. It is suggested that these persistent effects may have been caused by changes in resource allocation, flowering and senescence, which resulted in altered hormonal balance.
Modelling of early infection of cereal roots by the take‐all fungus: a detailed mechanistic simulator
Authors: GILLIGAN C. A. , BRASSETT P. R. , CAMPBELL A. 
Published: April 2006

summaryA stochastic model is constructed to simulate the spatial and temporal spread of infection of the take‐all fungus, Gaeumannomyces graminis var. tritici (Sacc.) Arx & Olivier var. tritici Walker on seminal roots of wheat. The model is designed to synthesize information on the dynamics and spatial orientation of the growth of main seminal root axes of wheat and the dynamics of primary and secondary infection of the pathogen. Primary infection is initiated by the soil inoculum. Three types of secondary infection by runner hyphal growth are distinguished; re‐infection of the same root, infection of another root on the same plant via the crown, and cross‐infection between roots on different plants. There are nine pathogen parameters, 14 host parameters, as well as four system parameters in addition to the location and orientation of seedlings. The pathogen parameters comprise estimates for the size and density of inoculum, the rate of growth of the fungus on roots, and the mean distances and probability of occurrence for primary and secondary infection. The host parameters concern orientation, density, emergence, rates of growth and size of roots. The principal output variables are total and infected root length, numbers of infections, proportion of infected roots and the numbers of primary and cross infections. Results of sensitivity analysis of the output variables to selected input parameters are presented. The model is tested against independent data‐sets from inoculum‐density experiments for different soil temperatures and ranges of inoculum density. Statistical methods of response curve analysis are used to compare the behaviour of inoculum density‐disease response curves for the simulated and experimental data. The model fitted the data satisfactorily for the majority of host and infection variables. Inclusion of secondary infection in the model improved the goodness‐of‐fit but the density of secondary infections was small relative to primary infections. Practical and conceptual problems in the validation of complex simulation models for fungal infection are discussed. The advantages and limitations of this and related models are critically assessed.
The dynamics of infection by the take‐all fungus on seminal roots of wheat: sensitivity analysis of a stochastic simulation model
Authors: GILLIGAN C. A. 
Published: April 2006

summaryThe effects and interactions of inoculum density (Iρ), rate of fungal growth (kf) and the maximum distances for primary (wp) and secondary (cross) (ws) infection on the temporal progress of infection of the take‐all fungus, Gaeumannomyces graminis, in small populations of contiguous wheat plants are examined in factorial combination using a stochastic simulation model. The effects are analyzed in relation to infection progress curves for the percentage infected roots, the total length of infected root, the density of separate infection and the mean length of separate infections as well as the densities of primary and cross infections. Linear models are used to analyze the effects of changing parameter values on components of the infection progress curves. Non‐linear, logistic models are used to summarize infection progress curves and to map the effects of changing simulation model parameters onto the parameters of the simpler, growth curve function. The proportion of infected roots was most influenced by Iρ and wp with a negligible effect due to ws. The density and length of infections on roots was principally controlled by kf. Changes in infection length were non‐monotonic. The average length of infections increased towards a temporary maximum, following the first wave of primary infections, dipped as infections overlapped and then increased rapidly as root colonization progressed. The first wave of cross infection occurred 7 d after the initiation of primary infection. The density of primary infections was controlled principally by Iρ and wp. The density of cross infections was controlled not only by kf and ws, which are directly involved in cross infection, but also by kf and wp which affect the amount of infected and susceptible tissue. The asymptotic parameter of the logistic model for the infection progress curves was the most frequently affected parameter, followed by the delay parameter, with relatively few changes affecting the rate parameter. Some problems in the use of complex, stochastic simulation models to simulate experimental conditions are discussed.
Regulation of somatic embryogenesis in long‐term callus cultures of sugarcane (Saccharum officinarum L.)
Authors: BRISIBE EBIAMADON ANDI , MIYAKE HIROSHI , TANIGUCHI TAKESHI , MAEDA EIZO 
Published: April 2006

summaryEmbryogenically competent callus was induced from in vitro grown Saccharum officinarum L. (NCo 310) plantlets by plating young leaf segments on MS basal medium supplemented with 30 μM dicamba for 21 d in darkness, and subsequently transferring to a medium (EFDM) on which embryos could form and develop. Embryogenic response was improved if the EFDM was supplemented with 1 or 5 μM dicamba, casein hydrolysate (1 g 1−1), and 6% maltose or 6–9% corn syrup. Calli maintained their embryogenic competence for up to 16 months under these conditions, and with alternate weekly subcultures on to fresh media containing 20 μM and 30 μM dicamba in the dark, embryogenic callus proliferation could be further increased. Additional improvements in embryogenic competence were optimized to over 40 months when primary callus was alternately precultured at weekly intervals either with 10‐5 M ABA or 5% sorbitol and then transferred to a medium containing 20 or 30 μM dicamba during maintenance. In general, medium plant growth regulator and nutritional cues, especially dicamha concentration, maltose/corn syrup levels and ABA/sorbitol preconditioning, were observed to influence critically both embryogenic callus proliferation and the frequency of somatic embryogenesis. The data are discussed within the context that these treatments can be successfully manipulated to enhance long‐term embryogenic competence and high‐frequency somatic embryogenesis in sugarcane.
A chamber system for exposing rice (Oryza sativa L.) to ozone in a paddy field
Authors: KOBAYASHI KAZUHIKO , OKADA MASUMI , NOUCHI ISAMU 
Published: April 2006

summaryA field exposure chamber system was constructed in a paddy field. The system consisted of four ozone generators, five exposure chambers equipped with ventilation fans on both ends, and an ozone measurement and control system. Rice plants were exposed to ozone in the exposure chambers for the whole growing season. The ozone concentration in each chamber was maintained in a constant proportion to ambient ozone. The horizontal distribution of ozone concentration within a chamber showed ±10%, of variation with the lowest values at the centre and both ends of the chamber. Wind velocity showed a similar horizontal distribution as ozone but with a greater variation among the locations within a chamber. Diurnal as well as seasonal changes of ozone concentration in the chambers followed the targeted level rather closely except for several occasions of power failure or system malfunctioning. Temperature in the chambers was c. 1 °C higher in the daytime and 0.34 °C higher on daily average than in the field outside. Light flux density in the chambers was reduced to 75% of that outside with little seasonal variation. These results indicated a satisfactory performance of the field exposure chamber system for its intended use.
Corrigiola litoralis L. in the British Middle Pleistocene
Authors: FIELD MICHAEL H. 
Published: April 2006

summaryPlant macrofossil analyses of fossiliferous silt and sand channel‐fill deposits from The Brays Pit near Mathon in the English West Midlands yielded the first record of Corrigiola litoralis L. in the British Middle Pleistocene. The presence of Corrigiola litoralis at this site shows that this taxon has occurred naturally in the British Isles. This may support the opinion that one of the extant populations of this species in south‐west England may be regarded as native. The stratigraphic context of the site is briefly considered followed by a description of the macroscopic remains.
Tansley Review No. 70 Signal transduction during fertilization in algae and vascular plants
Authors: BROWNLEE COLIN 
Published: April 2006

summaryFertilization involves interaction between two gametes and exchange of genetic information. In addition, information is transferred which results in triggering of the particular cellular and developmental responses of the organism. This review considers the cellular signals involved during different stages of gamete interactions in plants, including gamete attraction, recognition, fusion, zygotic activation and development. A wide range of signalling mechanisms can be seen to operate during fertilization, reflecting both the diversity of systems bringing gametes together and the different cellular responses to fertilization throughout the plant kingdom. Moreover, signals involved in triggering early development following gamete fusion appear to differ significantly even between species showing at least superficially similar cellular responses. Much of our current understanding comes from studies of a few easily accessible systems though recent developments in gamete isolation, in vitro fertilization and embryo culture should increase the scope for studies of signalling mechanisms in vascular plants.

Contents

Summary
399

I.
Introduction
400

II.
Chlamydomonas: interaction between structurally identical gametes
401

III.
Fucoid algae: a simple oogamous system
409

IV.
Vascular plants
412

V.
Concluding remarks
418

Acknowledgements
418

References
418
Tansley Review No. 71 Effects of elevated atmospheric CO2on woody plants
Authors: CEULEMANS REINHART , MOUSSEAU MARIANNE 
Published: April 2006

summaryBecause of their prominent role in the global carbon balance and their possible carbon sequestration, trees are very important organisms in relation to global climatic changes. Knowledge of these processes is the key to understanding the functioning of the whole forest ecosystem which can he modelled and predicted based on the physiological process information. This paper reviews the major methods and techniques used to examine the likely effects of elevated CO2on woody plants, as well as the major physiological responses of trees to elevated CO2. The available exposure techniques and approaches are described. An overview table with all relevant literature data over the period 1989‐93 summarizes the percent changes in biomass, root/shoot ratio, photosynthesis, leaf area and water use efficiency under elevated CO2. Interaction between growth, photosynthesis and nutrition is discussed with a special emphasis on downward regulation of photosynthesis. The stimulation or reduction found in the respiratory processes of woody plants are reviewed, as well as the effect of elevated CO2on stomatal density, conductance and water use efficiency. Changes in plant quality and their consequences are examined. Changes in underground processes under elevated CO2are especially emphasized and related to the functioning of the ecosystem. Some directions for future research are put forward.ContentsSummary425I.Introduction426II.The special case of trees426III.Methodologies, strategies and techniques427IV.Physiological responses of trees to elevated CO2428V.Conclusions: Looking forward to the future at the ecosystem level441Acknowledgements442References442
Sulphate and antioxidants in needles of Scots pine (Pinus sylvestrisL.) from three SO2‐polluted field sites in eastern Germany
Authors: POLLE ANDREA , EIBLMEIER MONIKA , RENNENBERG HEINZ 
Published: April 2006

summaryNeedles from young and mature Scots pine trees (Pinus sylvestirs) were collected at three field sites in eastern Germany, i.e. Menz, Taura, and Gossa, which differed in SO2pollution. Current and previous year's needles from the polluted sites Taura and Gossa (yearly mean af SO2: 26 ppb) contained approximately 100‐120 μmol sulphate g−1d. wt, whereas needles tram the unpolluted site, Menz (yearly mean of SO2: 3 ppb) contained 30‐65 μmol sulphate g−1d. wt. The apoplastic sulphate content was in the order of o.3‐1% of total sulphate and corresponded to concentrations of 0.6‐1.2 mM in needles from Mtnz and to 1.5–2 mn in needles from Gossa. In needles from the polluted sites the contents of glutathione, cysteine, γ glutamyleysteine, and soluble protein were higher than in needles from Menz. Despite the clear increases in sulphur‐containing compounds, pigment content and activities of superoxide dismutase, total peroxidase and apoplastic peroxidase (on the basis of d. wt) were not significantly different. When enzymatic activities were related to protein, lowest activities were found in needles from the site with the highest SO2‐pollution. The results show that it is not possible to use the activities of peroxidases or superoxide dismutases as biomarkers for SO2‐mediated stress in pine needles. It remains open whether the needles from the polluted sites suffered from greater oxidative stress than the needles from the less polluted site.
Analysis of aspen foliage exposed to multiple stresses: ozone, nitrogen deficiency and drought
Authors: GREITNER CAROL S. , PELL EVA J. , WINNER WILLIAM E. 
Published: April 2006

summaryTwo field experiments were conducted to examine the impact of a foliar stress (ozone, O3), alone or in combination with a resource stress, on carbon gain of aspen (Populus tremuloides Michx.). The first experiment involved nitrogen deficiency, and the second, drought stress.The patterns of change in leaf area, photosynthetic rate and carbon pain with leaf position from root to apex were altered by O3 alone. Net photosynthesis, and carboxylation capacity of older leaves decreased, and of younger leaves increased, in response to O3. Thus younger leaves partially compensated for the decreased photosynthetic capacity of older leaves. Physiological maturity and senescence were accelerated by O3. Whole plant carbon gain declined with O3 due to reductions in both leaf area and photosynthetic rate.Nitrogen deficiency alone decreased carbon gain via reductions in both leaf area and photosynthetic rate across leaf position. The effects of O3 and nitrogen deficiency together on both leaf area and photosynthetic rate were additive, Aspen seedlings compensated to O3 stress regardless of nitrogen level. Plant responses to both of these stresses may have been mediated by ribulose bisphosphate carboxylase/oxygenase (Rubisco) content or activity, and thus indirectly by nitrogen content.In the second experiment, seedlings were subjected to drought during the first six weeks of exposure to O3 and were measured several weeks after termination of the drought treatment. Drought caused aspen seedlings to produce fewer and smaller leaves. After termination of drought, they produced larger new leaves, and net photosynthesis of most leaves was greater than in continuously well‐watered plants. In plants not exposed to O3, enhanced photosynthetic rate partially compensated for the smaller leaf area. O3 generally decreased leaf area and photosynthesis, and hence carbon gain. The effects of prior exposure to drought and O3 together were additive for whole‐plant photosynthetic rate, but less than additive for whole‐plant leaf area.
Tansley Review No. 75 Arabidopsis– its use in the genetic and molecular analysis of plant morphogenesis
Authors: PYKE KEVIN 
Published: April 2006

summaryIn the last decade, the weed Arabidopsis thaliana has come to prominence as a major new model system for investigating genetic and molecular aspects of developmental plant morphology. Extensive genetic and molecular information about the Arabidopsis genome, facilitated by international collaborations and the production of novel mutagenic systems, has enabled a vast array of mutants to be identified, most of which reveal nuclear genes that control different aspects of plant developmental processes. An ever increasing number of these newly identified genes have been isolated and within the next few years an overall view of the molecular control of plant development is likely to emerge. Particularly prevalent amongst these Arabidopsis mutants are those which alter morphogenic processes cither by changes in differentiation patterns of specific cell types, homeotic conversion of entire structures or abnormal patterns of cell division.Mutants in the control of morphogenesis of most parts of the Arabidopsis plant have been identified and characterized. The most abundant classes are in embryogenesis including seedling pattern formation, root morphogenesis, floral morphology (including pollen and anther formation) and mutunts affecting shoot apical inenstern morphology. The first genes to be isolated from morphological mutants have been identified as transcription factors capable of controlling expression of other gene classes as part of a hierarchy of gene control. The relative ease with which many interesting and potentially important genes in morphogenesis have been revealed by identificatic.n of mutants makes it highly likely that with the aid of Arabidopsis thatiana, an understanding of the extremely complex molecular basis of plant morphogenesis may at last be Hirbin reach.

Contents

Summary
19

I.
Introduction
19

II.
Why Arabidopsis?
20

III.
The developing seed
22

IV.
The root
25

V.
The shoot apex
27

VI.
The Leaf
28

VII.
Whole plant morphology
30

VIII.
Floral development
31

IX.
Sub‐cellular tnorphology
32

X.
Discussion and future possihihties
32

XI.
Acknowledgements
32

XII.
References
34
Cytological events induced by arachidonic acid in potato tubers
Authors: ALTAMURA M. M. , CASTORIA R. , FABBRI A. A. , TOMASSI M. , FANELLI C. 
Published: April 2006

summaryNecrosis of potato tuber cells is enhanced, after 24 h incubation, by arachidonic acid (AA), an elicitor of the hypersensitive response in Solarium tuberosum L. and also by Fenton's reagents (a hydroxyl radical‐generating system) either alone or in association with AA. The phenomenon is independent of tuber age. In aged tubers, phenylthiourea (PTU) causes a significant reduction of AA‐induced cell necrosis. Necrosis observed in the presence of PTU alone is lower than in other treatments, and neither different from the controls nor affected by‐tuber age. Cell size is not affected by treatments or ageing. Nuclear hypertrophy occurs independently of tuber ape, with the highest values after treatment with AA and Fenton's reagents. Nucleolar extrusion is observed in all treatments but earliest in the presence of AA. AA also enhances the number of lignified parenchymal cells and, to a lesser extent, the number of traeheary elements.
Interactions between arbuscular mycorrhizal fungi and foliar‐feeding insects inPlantago lanceolataL.
Authors: GANGE A. C. , WEST H. M. 
Published: April 2006

summaryA field experiment was conducted to investigate whether infection by arbuscular mycorrhizal (AM) fungi has any effect on herbivory by foliar‐feeding insects. Plantsof PI ant ago laureolataL. were grown in a randomized block design and natural levels of mycorrhizal infection reduced by the application of the granular fungicide iprodione. Plant growth responses were examined and herbivore bioassays performed by rearing both a chewing and sucking insect on the leaves of mycorrhizal and fungicide‐treated plants.Fungicide application successfully reduced mycorrhizal infection, and this led to reductions in foliar biomass, caused by lower leaf number. However, fungicide‐treated plants suffered consistently higher levels of damage by centralist chewing and leaf‐mining insects, which colonized the plants. The chewing insect bioassay confirmed the field results, in that larvae ofArttia cajaL. (Lepidoptera: Arctiidae) consumed more leaf material from plants in which infection was reduced.There was no evidence that AM fungi altered food quality for the chewing insect. Instead, infection caused an increase in the carbon/nutrient balance, which in turn led to increased levels of the carbon‐based feeding deterrents, aucubin and catalpol,The sucking insect,Mvzus perskae(Sulzer) reacted in an opposite fashion to the ehewtr. with performance being greater on mycorrhizal plants. Again, there was no evidence that an alteration in food Quality was the cause, and in this case infection may result in changes in leaf morphology which benefit the insect.We suggest that under conditions of high light and low nutrient availability. AM infection can alter the carbon/nutrient balance of plants, leading to an increased allocation to carbon‐based defences. This can have important consequences for insect herbivore performance and the patterns of herbivory in field situations.
A new method to quantify the inoculum potential of arbuscular mycorrhizal fungi
Authors: LIU R.‐J. , LUO X.‐S. 
Published: April 2006

summaryPreviously described concepts of inoculum potential (IP) and methods to measure the IP of arbuscular mycorrhizal fungi (AMF) are reviewed. The concept of IP is elusive and needs developing‐ A new definition of IP is described here us the number of viable fungal propagules and structures coupled with their initial infectivity, and the IP can be calculated from the formula IP =(N × H × K)+S or IP = (N × L) +S, where N= numbers of vesicles in roots and points of hyphae connected with the roots per unit length of the roots; W= root weight; K= root length per unit weight of the roots; L= root length: S= numbers of viable spores in an inoculum. For the AMF that product spores in roots, few spores, or no spares, the formula becomes IP =N × W × K = N × L. The parameter of the IP is therefore the total numbers of vesicles and/or spores in roots, points of hyphae connected with roots, and viable spores in an inoculum of any type. The correlation coefficients between the IP of the inoculum of Glamus Mossear (Nicol. &Gerd.) Gerdemann &Trappe, Glomus versiforme (Karsten) Berth,or Sclerocystis sinuosa Gerdemann &Bakhi and the amount of early stage infection produced by the corresponding were all > 0.93 (P < 0.01)on three host plants. Gassypium hirsutum L., or Sarghum Sudanense L., It is suggested that the IP should be easily and rapidly estimated with accuracy by the present method.