bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationships and hybridization between British species of Polygala– evidence from isozymes
Authors: LACK ANDREW J. 
Published: April 2006

summaryIn Britain there are four species of Polygala, three diploids, P. serpyllifolia, P. calcarea and P. amarella, and a tetraploid, P. vulgaris, all of which are morphologically similar. Isozymes of six enzyme systems in these species were compared. Using evidence from both morphology and isozymes, the closest relationship within the group is between P. serpyllifolia and P. vulgaris. Despite this, P. serpyllifolia and P. vulgaris do not hybridize, whereas P. calcarea and P. amarella both hybridize with P. vulgaris in natural populations. In four sites, where P. calcarea and P. vulgaris occur together, there is good evidence for introgression via hybrids of P. calcarea genes into the tetraploid P. vulgaris, despite the high level of sterility in hybrids. Introgression of P. vulgaris genes into P. calcarea might have occurred at one site.
Effects of SO2 on the concentrations of carbohydrates and secondary compounds in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings
Authors: KAINULAINEN P. , HOLOPAINEN J. K. , OKSANEN J. 
Published: April 2006

summaryScots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings of open‐pollinated progenies and clonal cuttings were exposed to various concentrations of SO2 (50–155 nl l−1) in several growth chamber experiments. No visible foliar injury was observed in any SO2 exposure. The total sulphur concentrations of the exposed needles were significantly greater than in the control needles. Exposure to SO2 (100 and 155 nl l−1) reduced concentrations of glucose and fructose and increased concentrations of sucrose in pine needles. By contrast, one spruce clone had more glucose and fructose and less sucrose in needles exposed to SO2 (100 nl l−1), but in other spruces of clonal or open‐pollinated progenies no changes in sugar concentrations were detected in different SO2 exposures (50–155 nl l−1). Exposure to SO2 had no effects on concentrations of individual or total monoterpenes in pine or spruce needles. Concentration of total resin acids was significantly smaller in needles exposed to the greatest concentration of SO2 (155 nl l−1), but no changes were detected in other exposures (50–150 nl l−1) in either tree species. Concentrations of minor individual resin acids, palustric and neoabietic acids, were also affected by SO2 in needles of pine (155 nl l−1 SO2) and clonal spruces (100 nl l−1 SO2). Exposure to SO2 did not affect foliar concentration of total phenolics in pine and spruce seedlings. In exposure to 0, 50, 100 and 150 nl l−1 SO2, total phenolic concentration of spruce roots was increased linearly with elevated SO2 exposure level. By contrast one spruce clone had decreased concentrations of phenolics in roots after exposure to 155 nl l−1 SO2. The present results suggest that in conifers the response of carbohydrate and secondary metabolism to SO2 varies with the origin of tested seedlings and the SO2 concentration. Therefore, generalizations about the SO2 effects on suitability of food quality for folivorous herbivores are difficult to draw, except that a better supply of sulphur will be available from SO2 exposed seedlings.
The effect of natural and simulated insect herbivory, and leaf age, on the process of infection of Rumex crispus L. and R. obtusifolius L. by Uromyces rumicis (Schum.) Wint.
Authors: HATCHER PAUL E. , AYRES PETER G. , PAUL NIGEL D. 
Published: April 2006

summaryThe development of uredinia of Uromyces rumicis (Schum.) Wint. was studied on Rumex crispus L. and R. obtusifolius L. plants inoculated in the laboratory. Fewer uredinia developed on leaves injured by simulated insect herbivory, those fed upon by Gastrophysa viridula Degeer (Coleoptera: Chrysomelidae), and young, incompletely expanded leaves, than on uninjured, fully expanded control leaves. The effect of simulated herbivory and leaf age on the process of U. rumicis infection was investigated using Calcofluor staining and epifluorescence microscopy. Simulated insect herbivory reduced significantly the proportion of sporelings producing appressoria and the proportion of sporelings with appressoria that entered the substomatal cavity. In R. obtusifolius, leaf injury also reduced the proportion of penetration hyphae that formed substomatal vesicles. The proportion of sporelings that produced intercellular hyphae in injured leaves was reduced by 58 % in R. crispus and 89 % in R. obtusifolius. G. viridula feeding induced similar resistance in R. obtusifolius leaves.Simulated insect herbivory reduced both uredinial density and the area occupied by intercellular hyphae by between 65% and 89%. Injury had a greater effect than leaf age on sporelings in the pre‐haustorial stages of development. However, the total area occupied by intercellular hyphae in young leaves was reduced by between 42% and 78% compared to mature leaves, owing to a lower uredinial density and, in R. obtusifolius, also to a significant reduction in the size of individual uredinia.
Diversity of fungal symbionts in arbuscular mycorrhizas from a natural community
Authors: CLAPP J. P. , YOUNG J. P. W. , MERRYWEATHER J. W. , FITTER A. H. 
Published: April 2006

summaryThe arbuscular mycorrhizal (AM) association between fungi in the order Glomales and the roots of a very wide range of vascular plants is of global ecological significance but has proved particularly intractable to study in the field. We have developed a reliable technique to identify the fungal symbionts in roots taken directly from natural communities. Selective Enrichment of Amplified DNA combines the use of recently‐developed specific DNA primers with a novel method based on the principle of subtractive hybridization to remove interfering plant‐derived DNA after amplification with the polymerase chain reaction. Using this technique we have shown that endomycorrhizas of bluebells (Hyacinthoides non‐scripta) sampled directly from a woodland habitat are multispceies communities of varying composition which contain at least three genera of mycorrhizal fungi. The technique works well on a range of plant species and should have wide application to the identification of other symbionts, including pathogens. A spore survey has indicated that two particular AM types are associated with bluebells and this observation corroborates the molecular data. The presence of a Glomus species in bluebell roots was not expected from the spore data.
Endophyte infection effects on stomatal conductance, osmotic adjustment and drought recovery of tall fescue
Authors: ELMI A. A. , WEST C. P. 
Published: April 2006

summaryPresence of the endophytic; fungus Acremonium coenophialum Morgan‐Jones and Gams in tall fescue (Festuca artuidinacea‐ Sehreb.) enhances host persistence in drought‐prone environments. However, the physiological mechanism is not well understood. We investigated the influence of endophyte infection and water deficit on osmotic adjustment, stomatal conductance, tiller survival and leaf elongation rate of genotype GA87‐122 and cv. Kentucky‐31 (KY31) of tall fescue. Plants were grown in a greenhouse in pots containing fine‐silty topsoil (experiment 1) or sand (experiment 2). In expt 1, endophyte‐infected (EI) and endophyte‐free (EF) isolines of GA87‐122 were exposed to two drought preconditioning cycles, after which all pots were re‐watered and osmotic adjustment determined. Osmotic adjustment was −0.46 and −0.51 MPa in El leaf blades and tiller bases and −0.29 and −0.13 MPa in EF leaf blades and tiller bases, respectively. In expt 2, EI and EF GA87‐122 and KY31 Mere exposed to severe drought after two preconditioning cycles, then re‐watered. During the second preconditioning drying cycle of KY31, stomatal conductance tended to be lower in EI than in EF plants, but the difference was significant (P⩽ 0–05) only at two sampling times. Shoot tissues osmotically adjusted 0.17–0.31 MPa more in EI than in EF plants. Tiller survival and leaf elongation rates were higher (P⩽ 0.05) in preconditioned EI than in EF plants. Basal‐zone osmotic adjustment was correlated with tiller survival rate in GA87‐122 and KY31 (r = 0.87, P⩽ 0.01 for both). Enhanced osmotic adjustment in the meristematic and growing zone might account far improved survival of tillers by facilitating protection of the apical meristem.
Leaf growth of hybrid poplar following exposure to elevated CO2
Authors: GARDNER SIMON D. L. , TAYLOR GAIL , BOSAC CREANA 
Published: April 2006

summaryLeaf extension was stimulated following exposure of three interamerican hybrid poplar clones (Populus trichocarpa P. deltoides); ‘Unal’, ‘Boelare’, and ‘Beaupre’ and a euramerican clone ‘Primo’ (Populus nigra×P. deltoides) to elevated CO2, in controlled environment chambers. For all three interamerican clones the evidence suggests that this was the result of increased leaf cell expansion associated with enhanced cell wall extensibility (WEx), measured as tensiomerric increases in cell wall plasticity. For the interameriean clone ‘Boelare’, there was also a significant increase in cell wall elasticity following exposure to elevated CO2 (P⩽ 0.001). The effect of elevated CO2 in stimulating cell wall extensibility was confirmed in a detailed spatial analysis of extensibility made across the lamina of expanding leaves of the clone ‘Boelare’. For two of the interamerican hybrids, ‘Unal’ and ‘Beaupre’, both leaf cell water potential Ψ and turgor pressure (P) were lower in elevated than in ambient CO2. By contrast, no significant effects on the cell wall properties or leaf water relations for the euramerican hybrid ‘Primo’ were observed following exposure to elevated CO2. suggesting that the mechanism for increased leaf extension in elevated CO2, differed, depending on clone. The cumulative total length of leaves of ‘Boelare’ grown in elevated CO2, was significantly increased (P≤ 0.05) and since leaf number was not significantly increased in any inter‐american clone it is hypothesized that final leaf size was stimulated in elevated CO2 for these clones. By contrast, there was no significant effect of CO2 on cumulative total leaf length for the euramerican clone ‘Primo’, but leaf number was significantly increased by elevated CO2. The measurements suggest that total tree leaf area was stimulated for a range of poplar hybrids exposed to elevated CO2. Given the short rotation of a coppiced crop, it is likely that increased leaf areas will result in enhanced stemwood production when hybrid poplars are grown in the CO, concentrations predicted for the next century.
Secondary thickening in roots of Arabidopsis thaliana: anatomy and cell surface changes
Authors: DOLAN LIAM , ROBERTS KEITH 
Published: April 2006

summaryThe root of Arabidopsis thaliana (L.) Heynh. undergoes dramatic morphological changes during secondary thickening. We have used monoclonal antibodies that recognize two cell surface arabinogalactan protein epitopes (AGPs) and a pectic polysaccharide to document cell surface changes during the process of secondary thickening. These antibodies recognize cells in various stages of differentiation. An AGP epitope recognized by JIM 14 is expressed at the plasma membrane of most tells in the root, but is most highly expressed in mature sieve tube elements, JIM 13 identifies an epitope that is expressed in a discrete ring of cells in the periderm and during xylem vessel element differentiation, disappearing as lignificntion of the vessel elements proceeds, These antibodies reveal a biochemical differentiation at the surface of cells which mirrors obvious morphological differentiation events. Since AGPs have been shown previously to have a dramatic effect on the developmental capabilities of cells it is possible that the epitopes recognized by these antibodies might have an important developmental role during differentiation.
The influence of CO2concentration on stomatal density
Authors: WOODWARD F. I. , KELLY C. K. 
Published: April 2006

summaryA survey of 100 species and 122 observations has shown an average reduction in stomatal density of 14.3% (SE ±2.2 %) with CO2enrichment, with 74% of the cases exhibiting a reduction in stomatal density. A sign test demonstrated that stomatal density decreases, in response to CO2, significantly more often than expected by chance. Repeated observations on the same species indicated a significant repeatability in the direction of the stomatal response. Analyses which removed the potential effect of taxonomy on this data set showed no significant patterns in the dependency of the degree of stomatal change on growth form (woodiness vs. non‐woodiness; trees vs. shrubs), habitat (cool vs. warm) or stomatal distribution on the leaf (amphi‐ vs. hypostomatous).Forty‐three of the observations had been made in controlled environments and under a typical range in CO., enrichment of 350–700 μmol mol−1. For these cases the average stomatal density declined by 9% (SE ± 3.3%) and 60% of the cases showed reductions in stomatal density. When analyses were restricted to these 43 observations, amphistomatous samples more frequently had greater changes in stomatal density than did hypostomatous samples.The degree of reduction in stomatal density with increasing CO2increases with initial stomatal density, after the influence of taxonomy is removed using analyses of independent contrasts. When the data were examined for patterns that might be due explicitly to the effects of relatedness, the subclasses of the Hamamelidae and the Rosidae showed highly significant reductions in stomatal density with CO2(87% of the species studied in the Hamamelidae and 80% of the species in the Rosidae showed reduction with CO2enrichment) and correlations between initial stomatal density and degree of reduction in stomatal density. The species sampled in the Hamamelidae were dominantly trees, whereas herbs dominated the species in the Rosidae. There were insufficient species studied at lower taxonomic levels to warrant further statistical analyses. This problem results from experimental and observational data being most often restricted to one species per taxonomic level, typically up to the level of order, a feature which can severely limit the extraction of taxonomically‐related and ecologically‐related plant responses.
A rapid change in ozone resistance of Plantago major after summers with high ozone concentrations
Authors: DAVISON A. W. , REILING K. 
Published: April 2006

summaryOzone concentrations in Britain vary greatly from year to year. In the mid‐1980s they were relatively low but in 1989 and 1990 the number of hours when concentrations exceeded 60 nl 1−1 was 3–4 times greater than in the preceding 2 yr. Previous experiments suggested that this might have resulted in an increase in ozone resistance of Plant ago major L. populations, so a comparison was made of seed‐grown plants collected from the same three sites in Derbyshire/South Yorkshire in the 1980s and 1991. Ozone resistance was measured by exposure to charcoal‐filtered air or air containing 70 nl 1−O3 (7 h d−1) and expressed as R%, the mean relative growth rate in ozone expressed as a% of that in charcoal‐filtered air. Ozone resistance changed significantly in two of the populations (ISP and Totley) between the years 1985 and 1991. There was no significant change in the resistance of the Scaftworth population between 1988 and 1991 when expressed as R% but there were significant physiological differences between the collections. The changes in R% were accompanied by differences in the response of the stomata to ozone and in effects on dark respiration, but not in assimilatory capacity. This is the first report of a change in ozone resistance in populations over a short period of time. It is not known if the 1 991 plants were the descendants of the 1985/88 plants or whether there had been an invasion by new genotypes from outside the area. The role of other environmental factors in determining ozone resistance, and the implications of the data for the definition and mapping of critical levels are both discussed. It is predicted that if the reported changes were caused by ozone, the region where future changes in ozone resistance are most likely to occur is that between the Midlands and the north of England.
Short‐term exposure to atmospheric ammonia does not affect low‐temperature hardening of winter wheat
Authors: CLEMENT JOHANNES M. A. M. , VENEMA JAN HENK , VAN HASSELT PHILIP R. 
Published: April 2006

summaryThe effect of atmospheric NH3 an low‐temperature hardening of winter wheat (Triticum acstivum L. cv. Urban) was investigated. Growth and photosynthesis were stimulated by ammonia exposure. After a 14 d exposure at moderate temperatures (day/night 18.5/16°C) total nitrogen content was enhanced by 45 % compared with the controls. During that period, water‐soluble sugar content was not affected by NH3. After lowering the temperature to 4/3 0C, sugar content of the control plants doubled within 2 d, whereas in the plants exposed to NH3 it increased to a much lesser extent. Total nitrogen content further increased, leading to an 85%, higher level in the NH3‐exposed plants. Frost hardiness was not affected by atmospheric ammonia. It is concluded that winter wheat is tolerant Ed high ammonia concentrations, even under unfavourable growth conditions.
Axenic in vitro nitrogen and phosphorus responses of some Dutch marsh orchids
Authors: DIJK EEUWE , ECK NELLY 
Published: April 2006

summarySeedlings of Dactylorhiza majalis (Reichb.) Hunt & Summerh., D. praetermissa (Druce) Soó var.junialis (Vermen.) Sengh., D. incarnata (L.) Soo and D. maculata (L.) Soó ssp. maculata were grown axenically in vitro at various concentrations of ammonium nitrate and phosphate to assess the extent of growth depression owing to high nutrient availability. Only large nitrogen concentrations had a general negative effect on orchid axenic growth. Responses to both nutrients were highly species‐specific. D. praetermissa responded positively to addition of mineral nitrogen in the media, whereas D. incarnata showed the most negative response. D. majalis differed in showing preference for the greatest phosphate concentrations, in contrast to D. practermissa. Axenic nutrient responses might explain differences in distribution patterns between the tested species in the field.
Piceirhiza nigra, an ectomycorrhiza on Picea abies formed by a species of Thelephoraceae
Authors: AGERER REINHARD , KLOSTERMEYER DÖRTE , STEGLICH WOLFGANG 
Published: April 2006

summaryEctomycorrhizas of Picea abies (L.) Karst., previously described as Piceirhiza nigra, are shown to be formed by a member of the Thelephoraceae by virtue of the presence of thelephoric acid.
Diurnal water relations and gas exchange of two slash pine (Pinus elliottii) families exposed to chronic ozone levels and acidic rain *
Authors: JOHNSON J. D. , BYRES D. P. , DEAN T. J. 
Published: April 2006

summarySeedlings from two half‐sib families ofPinus elliottiivar.elliottiiEngelm. differing in sensitivity to ozone were grown in open‐top chambers for 22 months under simulated acidic rain (pH 3‐3) and four concentrations of ozone. The ozone concentrations were: charcoal‐filtered air (CF); non‐filtered ambient air (NF); twice the NF level (2X), thrice the NF level (3X). Ozone exposures were computer controlled to follow diurnal and seasonal fluctuations in ambient ozone concentrations.On two days, 24 April and 29 May, in the spring of 1990, trees were sampled repeatedly for xylem water potential, needle conductance and photosynthesis from sunrise to sunset on the oldest needle age class attached to the main stem (first needle cohort produced in 1989, and therefore, exposed the longest to ozone). On 30 May, three needle age classes (first age class of 1989, the last age class of 1989 and first ape class of 1990) were sampled over the day for needle conductance in trees exposed to CF and 3X ozone.Soil moisture measurements indicated that the 3X trees used significantly more water from the 75–l00 cm soil depth even though leaf area on these trees was about 30% less. Tree response showed very consistent xylem water potential among sample days, families and ozone treatments. By contrast, needle conductance and photosynthetic rate showed significant ozone and family differences. In addition, the response of needle conductance to vapour pressure deficit lessened as ozone exposure increased. The putative ozone‐sensitive family (106‐56) exhibited less needle conductance in the 2X and 3X treatments as well as reduced photosynthesis on both sample days, suggesting prior ozone injury. The youngest needle age class of this same family when exposed to 3X ozone showed higher needle conductance in the afternoon which could lead to both excessive water loss and uptake of ozone.The interactive effects of chronic ozone exposure, limited soil moisture and genetics altered the water relations and gas exchange of slash pine growing in north Florida. Changes in sromatal conductance along with possible adjustments in the hydraulic properties of the roots and stems appeared to be responsible for the control of water potentials in trees of differing sizes and leaf area. The importance of the contribution of different needle age classes to the water and carbon economy of slash pine, and their modification by cumulative ozone exposure, cannot he overlooked in interpreting air pollution effects on evergreen trees.
B chromosomes in plants
Authors: JONES R. NEIL 
Published: April 2006

summaryThis review of supernumerary B chromosome systems in flowering plants deals mainly with work published in the last 15 yr, hut also includes older material which has not hitherto been presented systematically. The term B chromosome (B) is defined, and there is an introductory overview dealing with general characteristics and the significance of Bs as a widespread chromosome polymorphism. Detailed sections are then presented covering the occurrence of Bs in different taxa, their structure and molecular organization, their irregular modes of inheritance, their phenotypic effects, population dynamics and origin. Particular attention is paid to the research growth points in molecular analysis of the structure and genome organization of Bs, and to transmission genotypes in the context of their adaptive versus their selfish properties. Where appropriate, reference is also made to likely future lines of research, and also to the usefulness of B chromosomes in genetic analysis and as model systems to study general phenomena of genome organization and evolution, nuclear physiology and architecture, chromosome polymorphism and selfish DNA.

CONTENTS

Summary
411

I.
Introduction
411

II.
Occurrence
411

III.
Structure and organization
415

IV.
Inheritance
422

V.
Phenotypic effects
426

VI.
Populations
429

VII.
Applications
430

VIII.
Origin
430

Acknowiedgements
430

References
431
On the cause of offspring superiority conferred by mycorrhizal infection of Abutilon theophrasti
Authors: KOIDE ROGER T. , LU XIAOHONG 
Published: April 2006

summaryIn previous studies we demonstrated that for Abutilon theophrasti Medic, offspring of mycorrhizal plants grew more rapidly than did offspring of non‐mycorrhizal plants. This observation was verified in the current study. We hypothesized that the faster growth of offspring of mycorrhizal plants was caused by a superior ability to absorb nutrients, since offspring of mycorrhizal plants produced faster‐growing root systems with higher phosphatase activities. We tested the hypothesis by growing offspring plants in distilled water. Despite the absence of any nutrients short‐term growth rates of offspring of mycorrhizal plants were still significantly greater than those of offspring of non‐mycorrhizal plants. We conclude that the faster growth of offspring of mycorrhizal plants is nor caused by a superior ability to acquire external resources.