bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics of plant species which store different types of reserve carbohydrates
Authors: BROCKLEBANK K. JANE , HENDRỲ GEORGE A. F. 
Published: April 2006

summaryThe occurrence of the three principal reserve carbohydrates, starch, fructan and sucrose, is documented in 20 native British species over four seasons. Species containing two of the reserve carbohydrates in different combinations were present in each of three common habitats.Sucrose reserves Undergo considerable depletion after winter. Starch depletion also occurs in many though not all species. In contrast, fructan is stored in high concentrations which are not subject to depletion. This indicates the fructan has functions other than as a source of consumable carbohydrate, one of which may be as an osmotic regulator.Fructan is associated with relatively restricted phenologies associated with early‐season, low‐temperature growth. In contrast, the Storage of starch or sucrose as a principal reserve carbohydrate is associated with the broadest variation in phenological patterns. There is, however, no indication that fructan has a unique or specific‐role in low temperature tolerance as similar attributes are shown to be present in a number of non‐fructan species.In relation to herbivore nutrition, each type of carbohydrate is made relatively unavailable either in space (starch and fructan) or in time (sucrose). The consequences of these various characteristics are considered in relation to plant evolution and Survival.
Adaptive speciation in Mimulus: an ecological comparison of M. cupriphilus with its presumed progenitor, M. guttatus
Authors: MACNAIR M. R. , MACNAIR V. E. , MARTIN B. E. 
Published: April 2006

summaryThe ecology of a recently evolved species, Mimulus cupriphilus, was compared with its presumed progenitor, M. guttatus. Both species live sympatrically as annuals on two small copper mines in Calaveras county, California, USA. There are almost no other species present in the areas where Mimulus dominates. The production of seed by the two species was compared. The relationship between capsule number and plant height differs, with M. cupriphilus having the steeper slope, so that at any particular height it produces more capsules. Mean seed number per capsule, and the relationship between seed number and size of plant, also varies between the two species. M. cupriphilus is normally sell‐fertilizing, and thus has a higher probability that a capsule will he fertilized than M. guttatus, which relies more on fertilization by insects. The various parameters can be combined to produce a predicted relationship between size of plant and seed production. When plants are small, M. cupriphilus will produce more seeds, but at heights greater than about V cm M. guttatus will be fitter. The overall resource allocation pattern also reveals that M. cupriphilus devotes a greater proportion of its dry weight to seed and capsule production. These results show that in the habitat where the two species co‐exist, arid deserted copper mines, the derived species is better adapted.
Pollen allelopathy among sympatric grassland species: in vitro evidence in Phleum pratense L.
Authors: MURPHY STEPHEN D. , AARSSEN LONNIE W. 
Published: April 2006

summaryPollen extracts from live locally‐common grassland species in eastern Ontario, Canada were tested for in vitro allelopathic effect on the pollen germination of 17 sympatric target species in 1987. The flowering phenologies of the test and target species were recorded to determine if any phenologically‐divergent species showed evidence of in vitro pollen‐allelopathic interactions. Phleum pratense L. demonstrated pollen‐allelopathic effects on all targets except Linaria vulgaris Hill. P. pratense also exhibited significant phenological divergence with seven of the target species. Pollen extracts from Agrostis stolonifera L., Melilotus alba Desr., and Vicia cracca L. inhibited pollen germination in some of the target species, but the results suggest that these effects were pH‐mediated. The pollen extract of Erigeron annuus (L.) Pers. did not cause inhibition of pollen germination in any of the target species. Further tests with pollen extract of P. pratense and another 23 sympatric target species were performed in 1988. Pollen germination was significantly inhibited in all but two of these species: A. stolonifera and P. pratense. Hence the pollen of P. pratense was not auto‐allelopathic. The breeding system, relatively tall growth habit and relatively large quantity of pollen produced all support the in vitro evidence of P. pratense as a pollen‐allelopathic species.
Characterization of a stigmatic component fromPapaver rhoeasL. which exhibits the specific activity of a self‐incompatibility (S–) gene product
Authors: FRANKLIN‐TONG VERNONICA E. , RUUTH ERIK , MARMEY PHILIPPE , LAWRENCE MICHAEL J. , FRANKLIN F. CHRISTOPHER H. 
Published: April 2006

summaryExtracts prepared from stigmatic tissue ofPapaver rhoeasL. have been fractionated and monitored for S–gene product activity. A basic glycoprotein, with an apparent MW of 22 kDa, which exhibits the specific activity expected of a protein encoded by the self–incompatibility (S–) gene has been identified. Similar preparations using extracts from other tissues have revealed that this protein is unique to mature stigma tissue.
Aluminium—phosphate interactions in wheat
Authors: de MIRANDA L. N. , ROWELLO D. L. 
Published: April 2006

SUMMARYTwo Brazilian wheat varieties (Triticum aestivum L., varieties IAC‐5 and Jupateco) were grown in solution culture with three concentrations of P (1, 5 and 20 μg ml‐1) and no Al, then transferred to three concentrations of Al (0, 2.5 and 12.5 μg ml‐1) and no P and afterwards returned to the first solutions. In the first growth period the tolerant variety IAC‐5 absorbed and translocated more P to the shoots than the sensitive one. In the second period A1 restricted both root growth and the translocation of P from root to shoot, and led to movement of P from shoots to roots in plants with low P contents, the sensitive variety again being most affected. The amount of P translocated to the roots was approximately equal to the increase in isotopically‐exchangeable P in the roots. In the third period, root P taken up in the first period was translocated to the shoots in amounts approximately equal to the total exchangeable P in the roots, along with freshly absorbed P. After the second period tissue was ground and filtered to give a filtrate (predominantly cell contents) and a residue (predominantly cell walls). The A1: P ratio (μmol g‐1 dry matter) in the contents was about 1:7, and in the walls it was 1:2. The latter value may indicate the composition of aluminium phosphate precipitated in the walls. Tolerance of soil acidity is associated with the ability of roots to translocate P to shoots in the presence of A1 and may also depend on the ability to move P down to roots growing in acid subsoils.
Interactions between fluorescent pseudomonads and VA mycorrhizal fungi
Authors: PAULITZ T. C. , LINDERMAN R. G. 
Published: April 2006

SUMMARYCucumber seeds were treated with rifampin‐resistant derivatives of Pseudomonas putida (A12, NI or R‐20) or R‐20 or P. fluorescens (2–79 or 3871) and planted in soils with and without added inoculum of the VA mycorrhizal fungi Glomus intraradices Schenck & Smith or G. etunicatum Becker & Gerdemann. Populations of Pseudomonas spp. in the combined rhizosphere‐rhizoplane soil were determined at 1–9 weeks after planting by dilution plating on a selective medium. At 1–3 weeks, the populations of all strains except R–20 were 1.5 to 7 times lower in the rhizosphere of cucumber roots colonized by G. intraradices, when compared to nonmycorrhizal plants. However, this effect was less consistent in 3‐ to 9‐week‐old plants. No significant difference was detected in populations of Pseudomonas strains between roots colonized by G. etunicatum and nonmycorrhizal roots. Strains 3871 and 2‐79, which are antibiotic producers, delayed the germination of G. etunicatum spores in raw soil, but by seven days no significant differences in frequency of germination were detected. None of the fluorescent Pseudomonas strains affected the colonization of cucumber roots by G. etunicatum, as determined by measurements of mycorrhizal inoculum density root colonization relationships.
Uptake, translocation and assimilation of nitrogen from 15N‐labelled ammonium and nitrate sources by intact ectomycorrhizal systems of Fagus sylvatica infected with Paxillus involutus
Authors: FINLAY R. D. , EK H. , ODHAM G. , SÜDERSTRÖM B. 
Published: April 2006

SUMMARYThe uptake and assimilation of nitrogen from 15N‐labelled ammonium and nitrate sources was followed in intact ectomycorrhizal systems containing Fagus sylvatica L. plants infected with the fungus Paxillus involutus (Mich. ex Pers.) Cohen & Couch. Plants were grown in flat perspex observation chambers containing non‐sterile peat; the fungal mycelium growing from a host plant was allowed to cross a barrier and to colonize an area of peat from which roots had been excluded. Labelled ammonium chloride or sodium nitrate was fed to the mycelium, and the shoot, root and mycelial tissues analysed for total and 15N‐labelled amino acid contents after a feeding period of 72 h. Both free and protein‐incorporated amino acids were analysed. Labelled nitrogen was incorporated into a range of free amino acids, the principal sinks for assimilation being alanine, aspartate/asparagine and glutamate/glutamine. The spectrum of labelling in protein‐incorporated amino acids was wider with significant incorporation into the above compounds but additional assimilation of nitrogen as glycine, valine, serine, leucine, isoleucine and arginine. In total 78% of the nitrogen assimilated was incorporated into proteinaceous material. Label was incorporated from both nitrogen sources but the levels of enrichment in most free and protein‐bound amino acids were usually higher in systems supplied with ammonium than in those supplied with nitrate. The mean amount of nitrogen assimilated From nitrate was only 62% of that assimilated from ammonium.
Fungi in healthy stems and branches of American beech and aspen: a comparative study
Authors: CHAPELA I. H. 
Published: April 2006

SUMMARYFungi inhabiting healthy stems and branches of American beech and aspen were induced to develop within the wood by drying sections of these organs. The two tree species were similar in that tile water content of the wood strongly determined fungal development, with a high water content preventing fungal growth for at least 25 weeks, fast drying resulting in poor development and slow drying inducing very fast growth of fungi within the wood. Fungal assemblages thus obtained were strongly dominated by ascomycetes and coelomycetes.Although some fungal species appeared on both tree species, assemblages of fungi obtained from each tree species were clearly different, even though samples of each were obtained from the same site and all experimental conditions were identical for both.All the characteristics mentioned above strongly resemble those documented for endophytes on smaller aerial tree organs such as leaves, petioles and twigs, and for this reason the fungi obtained here were termed‘xylotropic endophytes'.Among the dominant species found on aspen, three species with presumed pathogenic abilities were isolated. These were Cryptosphaeria populina, Cytospora chrysosperma and Hypoxylon mammatum. Hypoxylon fragifarme was the most frequently and abundantly isolated species obtained from beech.
Long‐term ozone exposure affects winter hardiness of red spruce (Picea rubens Sarg.) seedlings
Authors: FINCHER JEAN , CUMMING JONATHAN R. , ALSCHER RUTH GRENE , RUBIN GAIL , WEINSTEIN LEONARD 
Published: April 2006

SUMMARYRed spruce (Picea rubens Sarg.) seedlings were exposed to elevated levels of ozone during a growing season and into the period of early winter frosts. Samples were taken for histological analysis, chlorophyll content, and carotenoid content. Ozone treatments increased mesophyll cell disruption after frosts in early winter. Cell injury increased with increasing ozone concentrations up to 2 × ambient. In the spring, injury was assayed by ranking trees based on overall appearance and by counting the number of shoots with brown needles. Ozone treatments had no effect on winter injury as scored by the ranking method. There was also no effect on the number of injured flushes when all trees were considered. However, when only those trees exhibiting winter injury were considered, there was a small, but statistically significant effect of ozone on the number of injured shoots. Thus, there is evidence that ozone increases injury from freezing temperatures in the autumn. Ozone slightly increases browning in the spring in sensitive trees. There were no correlations between histological injury in the autumn and appearance in the spring, indicating that there may be different aspects of the winter injury syndrome.
Tansley Review No. 18 Mechanisms of resistance and pathogenic specialization in rust‐wheat interactions
Authors: DEVERALL B. J. 
Published: April 2006

SUMMARYForms of resistance and pathogenic specialization in interactions between wheat and its stem and leaf rust Fungi have been selected for analysis with two hypotheses in mind. One is that phytoalexin formation is a universal defence mechanism in plants; the other is that resistance is elicited specifically by products of avirulent strains of pathogens.A search for phytoalexins in wheat, using a range of extraction and separation procedures and a number of forms of expression of resistance, has indicated the presence of several inhibitors of fungal development but has yielded very little evidence for post‐infectional increases in the amounts of these inhibitors. No evidence for the formation of phytoalexins in wheat has been obtained. Hypersensitivity has been confirmed as being closely associated with the expression of most forms of resistance studied. Recent work with some very rapidly expressed forms of resistance to rust fungi has implicated lignification as a component of active defence in wheat, a finding in agreement with those of other workers.The expression of resistance conferred by the Lr20 gene towards avirulent strains of the leaf rust fungus was the principal subject of explorations for elicitors. Histological observations of the sequence of events in fungal and wheat cells suggested the action of rust strain and Lr20–specific elicitors in bringing about hypersensitivity. Experimental manipulations involving heat treatments or use of epidermis‐free segments of leaves incubated on infected mesophylls gave results consistent with this interpretation. Attempts to extract specific elicitors from infected leaves failed but yielded non‐specific elicitors. Non‐specific elicitors have been obtained in intercellular washing fluids of leaves infected with strains of both the leaf and stem rust fungi. They have also been obtained from extracts of germ tubes of both species of fungus. Although not specific for any known resistance gene, the elicitors are selective for a character determined by a factor on chromosome 5 A in some wheat cultivars. A role for the non‐specific elicitors as incompatibility factors between rust fungi and wheat is suggested.A revised hypothesis is presented in order to explain the evolution of pathogenesis in rust fungi towards wheat and it is discussed in relation to concepts of basic compatibility between pathogens and their hosts, as proposed also by others.

CONTENTS

Summary
233

I.
Introduction
234

II.
Working Ideas and Hypotheses
234

III.
The Search for Phytoalexins
235

IV.
Elicitation of Resistance
237

V.
Revised Hypothesis
240

Acknowledgements
242

References
242
Tansley Review No. 19 Environmental and endogenous controls of developmental pathways: variation and its significance in the forest pathogen, Heterobasidion annosum
Authors: STENLID J. , RAYNER A. D. M. 
Published: April 2006

SUMMARYCultural studies of the forest root pathogen Heterobasidion annosum (Fr.) Bref. have shown that the mycelium of the fungus possesses a high degree of developmental versatility, being able to grow in a variety of distinctive functional modes. Consequently the fungus can alternate between conidiogenous and meiotic reproductive pathways, rapid, sparsely branched and slow, densely branched mycelial extension, nutritive and non‐nutritive modes, and‘juvenile’and ‘senescent’phases. This ability is probably of considerable importance in natural infection cycles and provides an interesting model for examining interrelationships between developmental regulation and host‐pathogen interactions generally. It also raises important questions about the interface between environmental and endogenous controls of developmental pathways.

CONTENTS

Summary
245

I.
Introduction
245

II.
Spore germination and mycelial extension
246

III.
Production of non‐nutritive mycelium
249

IV.
Sporophore production, senescence, somatic incompatibility and extracellular enzyme production
251

V.
Discussion
254

Acknowledgements
255

References
255
Genetic variation of nitrate reductase activity in mono– and dikaryotic populations of the ectomycorrhizal fungus, Hebeloma cylindrosporum Romagnési
Authors: WAGNER F. , GAY G. , DEBAUD J. C. 
Published: April 2006

SUMMARYIntraspecific variability in the activity of nitrate reductase (NR) has been studied in the ectomycorrhizal fungus Hebeloma cylindrosporum Romagnési at the interstrain and intrastrain levels, the latter within a population of 11 wild dikaryotic strains collected in‘Les Landes’(SW France) at four locations less than 100 km away from one another. An attempt was made to determine whether variability within the monokaryotic and dikaryotic progeny of the HC1 fruiting strain could be used as a basis for an improvement programme involving breeding between selected monokaryons.The NR activity of the wild strains ranged from 201 to 700 nmol NO2 synthesized h‐1 mg ‐1 fungal protein whilst that of 20 sib‐monokaryons (5 per mating type) of the HCl strain varied from 51 to 510 nmol NO2 synthesized h ‐1mg‐1 fungal protein. Fifty controlled dikaryotic myeclia were obtained from all the compatible fusions with these monokaryons. In these, variation of NR activity was of the same order of magnitude as that recorded at the interstrain level, ranging from 72 to 689 nmol NO2 synthesized h ‐1 rag ‐1 fungal protein. Analysis of the components of the variation of NR activity in these controlled dikaryons demonstrated that the additive component of this variation accounted for less than 1 % of the total observed variation. The NR activity of any one controlled dikaryon could not therefore be predicted from the activity of its parental monokaryons However 14 of the 50 controlled dikaryons e8hibited an NR activity higher than that of the HCl parental dikaryon. These results indicate that breeding with sib‐monokaryons can be used as a basis for an improvement programme of NR activity in this ectomycorrhizal Basidiomycete.
Photosynthetic characteristics, stomatal responses and water relations of Fagus sylvatica: impact of air quality at a site in southern Britain
Authors: TAYLOR GAIL , DOBSON M. C. 
Published: April 2006

SUMMARYTransplants of beech (Fagus sylvatcia L.) were grown in open‐top chambers ventilated with either charcoal‐filtered or unfiltered air. From May until September measurements of stomatal conductance to water vapour (gs) were made on trees in the chambers. On six out of seven occasions, leaves which had expanded during the first flush (initial shoot extension, during May) in unfiltered air, had lower stomatal conductances, compared with those grown in filtered air; this was significant on three occasions (P < 0.05). Leaves which expanded later in the season (second Hush or lammas growth) responded differently to the air quality treatments, with greater stomatal conductances recorded for trees exposed to unfiltered air. Measurements of leaf (psychrometry) and shoot (pressure bomb) water relations indicated that air quality had little effect on turgor pressure (P). Values of solute (ψs) and water (ψw) potential were higher for trees grown in unfiltered air.Trees were transported to the laboralory for measurement of photosynthesis (A), transpiration (E) and stomatal conductance (gs). Measurements of CO, uptake were also made whilst the CO, concentration within the leaf (Cf) was experimentally controlled (A/Ci analysis). This revealed that higher rates of photosynthesis for lammas leaves grown in unfiltered air were due to enhanced regeneration of RuBP (increased Jmax, P < 0.08). Carboxylation efficiency (d.A/dCf) and percentage stomatal limitation were not significantly altered by air quality. Jmax and dA/dCi were similarly reduced following exposure to drought regardless of the air quality treatment.
Photosynthesis during winter in ryegrass/white clover mixtures in the field
Authors: WOLEDGE JANE , DAVIDSON I. A. , TEWSON VERONICA 
Published: April 2006

SUMMARYMeasurements of canopy gas exchange of mixed communities of ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) in the field during winter showed that instantaneous rates of gross photosynthesis were usually little less than those of canopies of similar leaf area at similar irradiance in summer. Respiration rates per unit dry weight were on average 25% less than those of comparable swards in summer. The daily totals of net photosynthesis, however, were as little as a tenth of summer values, because of the short photoperiods and low average irradiance. Clover leaf area tended to be positioned lower in the canopy than grass leaf area, especially towards the end of winter, and clover had a lower rate of photosynthesis per unit leaf area in situ than grass.
Storage of sugars and mannitol in petioles of celery leaves
Authors: KELLER FELIX , MATILE PHILIPPE 
Published: April 2006

SUMMARYMannitol and sucrose are produced photosynthetically in the mesophyll and translocated in the phloem of celery leaves. The thick and fleshy petioles of these leaves act as reversible carbohydrate sinks, storing mainly mannitol, glucose and fructose but very little sucrose (less than 3.3 mg ml‐1 sap) in their parenchyma. The concentrations of soluble carbohydrates and the activities of enzymes of sucrose cleavage were asayed in the petiole parenchyma during leaf development. Mannitol (about 20 mg ml‐1 sap), glucose and fructose (about 10 to 15 mg ml‐1 sap each), changed little with development. Soluble acid invertase accounted for over 95 % of the total enzymic sucrose cleavage measured in vitro. Its activity was closely related to development with a sharp decrease during leaf maturation.With protoplasts from petiole parenchyma and vacuoles isolated from them it was demonstrated that 28% of the total soluble acid invertase of the tissue was in the apoplast and 72 % in the vacuole. Alkaline invertase and sucrose synthase were totally cytosolic. Glucose and fructose, the main storage sugars of these protoplasts, were vacuolar in location, whereas mannitol was both cytosolic (19%) and vacuolar (81%).