bluuebunny/crossref_metadata_2025 huggingface dataset:
Nutrient availability, dimorphic seed production, and reproductive allocation in the annual grass Amphicarpum purshii
Authors: Cheplick G. P.
Published: April 2011

The effect of nutrient addition on dimorphic seed reproduction and biomass allocation was investigated in amphicarpic peanut grass (Amphicarpum purshii Kunth). This annual, which grows in disturbed habitats on the Coastal Plain of eastern North America, produces self-fertilizing cleistogamous spikelets under ground and potentially outcrossing chasmogamous spikelets above ground. For each of three sibling families raised in the greenhouse from aerial seeds, 11 plants were fertilized twice during the growth period while 11 plants received no fertilizer. Total spikelet output and seed weight increased in response to fertilizer addition for both aerial and subterranean reproductive components, but changes were greater for aerial reproduction. Biomass allocation to subterranean spikelets and seeds was unaffected by nutrient addition. As measured by coefficients of variation, phenotypic variation for six aerial reproductive characters was about twice as great as that for six subterranean reproductive characters. Subterranean and aerial seed output were significantly related to shoot biomass for fertilized plants, but only mean aerial seed weight showed a significant relation to biomass when nutrients were not provided. These results support the hypothesis that early subterranean seed production provides reproductive insurance in peanut grass, whereas later aerial reproduction on newly formed tillers allows plants to increase reproductive output at the end of the growing period according to the availability of resources.
Biométrie et symétrie des inflorescences de charme
Authors: Legay Jean-Marie
Published: April 2011

The studied area concerns the inflorescence of the yoke elm, Carpinus betulus, and especially the lobes of the involucre surrounding the fruit for groups of two flowers, which form these inflorescences. Data come from three natural populations, geographically distinct. Two fluctuating asymmetries and two directional asymmetries are noted in the system. Their characteristics and the relations between them are examined. The interpretation takes into account the ontogenesis of the flower structure and leads to a discrimination between populations.
Calamagrostis epigejos (Poaceae) in North America, especially Ontario
Authors: Aiken S. G. , Dore W. G. , Lefkovitch L. P. , Armstrong K. C.
Published: April 2011

The Eurasian grass, Calamagrostis epigejos (L.) Roth, has been both deliberately and accidentally introduced to North America. Deliberate introductions have usually been destroyed because the plants were weedy and difficult to confine. Introductions at approximately 50 sites, most of them accidental, are documented. While the grass sometimes is the dominant species over several square metres and can out-compete some other weedy species, only at two sites is it known to have spread more than 10 km in a 30-year period. One site is Ontario, Canada, along the road between Espanola and Whitefish Falls, and the other is Liberty State Park in New Jersey, U.S.A. There have been major earth moving projects at both sites so that spread of rhizomes as well as seed dispersal may have been involved. Data analyses of 16 characters used, or possibly useful, in recognizing intraspecific taxa are presented. Taxonomic recognition of C. epigejos as an amphimictic, polyploid complex is discussed. Application of the treatment given by Tzvelev to our data suggests that (i) ssp. extremiorentalis Tzvelev and ssp. macrolepis (Litv.) Tzvelev have each been introduced once into North America; (ii) most specimens in North America belong to ssp. epigejos, ssp. glomerata (Boiss. and Buhse) Tzvelev, or ssp. meinshausenii Tzvelev, but it is not always possible to distinguish among these subspecies with confidence; and (iii) C. epigejos var. georgica (C. Koch) Ledeb., as recognized by Fernald, is probably synonymous with ssp. glomerata. Plants collected from five sites in Ontario had chromosome counts of 2n = 28 + 4B. Plants of C. epigejos ssp. macrolepis from New York were 2n = 42.
The effect of added nitrogen and phosphorus on mycorrhizal growth response and infection in Allium schoenoprasum
Authors: Bååth E. , Spokes J.
Published: April 2011

The effect of different levels of phosphorus and nitrogen on mycorrhizal growth response and infection was studied using Allium schoenoprasum and Glomus caledonium. Nitrogen was added as ammonium or nitrate salt. Both the level of soil phosphorus and the level of nitrogen added affected the mycorrhizal growth response, which was greatest at intermediate levels of P and N. The nitrogen source did not affect the mycorrhizal growth response. At low levels of soil P, nitrogen addition did not affect mycorrhizal infection rate. High P and low N also had little influence. However, the combination of high P and high N gave much lower levels of mycorrhizal infection compared with the other treatments. This effect was most pronounced with ammonium N compared with nitrate N.
Some Zygnemataceae (Chlorophyta) of Ontario, Canada, including descriptions of two new species
Authors: Wei Yin-Xin , Yung Ying-Kit , Jackson Michael B. , Sawa Takashi
Published: April 2011

We examined 1455 filamentous algal samples collected from 32 Ontario sites since 1981 and identified 21 Zygnemataceae, including two new species: Spirogyra favosa Wei et Yung sp.nov. and Zygnema lacustre Wei et Yung sp.nov. Of the 21 taxa described in this paper, Zygogonium tunetanum, Temnogametum tirupatiense, Mougeotia quadragulata, and Spirogyra fennica were the important species in the acidic sites, whereas Mougeotia laetevirens, Zygnemopsis stephensiae, and Spirogyra jatobae were common in the circumneutral and alkaline locations. Zygogonium tunetanum was the most important metaphytic alga in lakes with pH 6.8 and lower, proliferating in the littoral areas of acidic Ontario lakes. These data support the view that the taxonomy of Zygnemataceae should place more emphasis on the zygospore wall structures and ornamentations and less emphasis on the dimensions of vegetative cells.
Species of Phyllosticta on conifers
Authors: Bissett John , Palm Mary E.
Published: April 2011

Four new species of Phyllosticta are described. Each is associated with needle blight or dieback of North American conifers. New combinations in Discochora are made for two Guignardia species with Phyllosticta anamorphs occurring on Pinaceae. A key is provided to Phyllosticta species and morphologically similar fungi currently known on Coniferae.
The ultrastructure of mitosis during zoosporogenesis in Rhizidiomyces apophysatus
Authors: Barstow W. E. , Freshour G. D. , Fuller M. S.
Published: April 2011

Mitotic divisions in reproductive thalli of Rhizidiomyces apophysatus, a monocentric, eucarpic hyphochytrid, were examined ultrastructurally. Mitosis is centric; each spindle pole contains two centrioles of unequal length that lie at a 108° angle relative to each other. The nuclear envelope persists throughout the entire mitotic cycle, although it is highly fenestrated at the poles. Centrioles, along with an accompanying dictyosome, appear to migrate to opposite poles during prophase. During metaphase, vesicles coalesce on the poleward surfaces of the chromatin plate. Ultimately, these vesicles and their fusion products form part of the daughter nuclear envelope. Some of these vesicles appear to develop from the original nuclear envelope. Separation of the chromatin during anaphase appears to be the result of elongation of interzonal microtubules. A dictyosome remains associated with each centriole pair throughout mitosis.
Morphology of Erysiphe pisi on leaves of Pisum sativum
Authors: Falloon Richard E. , Sutherland Paul W. , Hallett Ian C.
Published: April 2011

Morphological details of conidium germination, hyphae, appressoria, conidiophores, and organisation within colonies of Erysiphe pisi on leaves of Pisum sativum were studied in frozen, hydrated specimens with a scanning electron microscope. The pathogen has several adaptations to enable efficient colonisation of host leaf surfaces, including production of several hyphae from each germinated conidium, unidirectional growth of individual hyphae, prolific hyphal branching at obtuse angles to lines of hyphal growth, and rapid and prolific development of appressoria and conidiophores. Hyphal cells on leaf surfaces are specialised to produce either appressoria or conidiophores and hyphal branches.
Properties and uses of neem, Azadirachta indica
Authors: Koul Opender , Isman Murray B. , Ketkar C. M.
Published: April 2011

The versatility of the neem tree Azadirachta indica A. Juss. is reviewed. This species, native to India, grows in nutrient-poor soils in arid habitats and has tremendous potential for human use. Various derivatives of the tree have potential use in toiletries, pharmaceuticals, the manufacture of agricultural implements and furniture, cattle and poultry feeds, nitrification of soils for various agricultural crops, and pest control. Since neem is a natural renewal resource producing extensive useful biomass, its propagation and economic exploitation will be beneficial, particularly to the Third World. In recent years, some useful commercial products have been developed from A. indica, and mere is considerable scope for future product development. Potentially profitable lines of research on this plant species are suggested.
Effet de composés phénoliques et de substances provenant de l'appareil souterrain de la Pomme de terre sur la croissance et la sclérotifïcation in vitro du Rhizoctonia solani
Authors: Otrysko B. E. , Banville G. J. , Asselin A.
Published: April 2011

We tested the hypothesis that phenolic compounds initiate the formation of sclerotia in Rhizoctonia solani AG 3. Water soluble substances were recovered in situ from the underground parts of undisturbed potato plants by adsorption onto columns fitted with a water circulating device. These extracts inhibited mycelial growth of five isolates of R. solani belonging to anastomosis groups AG 1, AG 2, AG 3 and AG 4. However, there was no effect on the initiation of sclerotia. Fourteen phenolic compounds were bioassayed in vitro at concentrations ranging from 10−3 to 10−6 M against these same isolates. Phenolic acids had no significant effect on mycelial growth, whereas the substituted aldehydes were inhibitory at 10−3 and 10−4 M. There was no visible effect on sclerotial initiation.
Delimiting species among permineralized medullosan pteridosperms: a plant bearing Alethopteris fronds from the Upper Pennsylvanian of the Appalachian basin
Authors: Pryor Janelle S.
Published: April 2011

The vegetative anatomy of a medullosan pteridosperm is described and the morphology reconstructed from permineralized plant fragments found at a single outcrop of the Upper Pennsylvanian (Stephanian B equivalent) Duquesne Coal located near Steubenville, OH (U.S.A.). The frond is interpreted to be pinnately compound with four orders of branching. Primary pinnae are borne alternately on the rachis, and secondary pinnae (pinna rachises) are borne alternately on the primary pinnae. Pinnules are borne alternately on the pinna rachis. The frond is attached by a large decurrent base to a stem assignable to Medullosa noei. The stem of this plant is distinguished from similar stems (also assignable to Medullosa noei) of two other medullosan plants found within the same flora by histological features of the stem cortex and petiole bases. This suggests that the stem Medullosa noei Steidtmann 1937 emend. Delevoryas 1955 was produced by several different taxonomic species with similar growth forms found in a wide range of localities and stratigraphic levels.
Introduction
Authors: Catling P. M. , Reznicek A. , Crins W. J.
Published: April 2011

The genus Carex includes the sedges that dominate wetlands, pastures, prairies, tundra, and the herb layer of temperate forests. These plants are not only frequently dominant in terms of biomass in plant communities, but they are also prominent in terms of numbers of species. Carex is one of the largest genera in the Canadian flora with approximately 300 species, and consequently almost one-tenth of the native vascular plants of Canada are sedges. In North America there are about 500 species. Worldwide, there may be as many as 2000 species.The results of the recently increasing interest in Carex include regional taxonomic treatments, simplified identification, and many improvements to classification. Basic taxonomic work was supported through the application of chemical, anatomical, and cytological techniques. The first detailed ecological studies of Carex have been completed, and much general ecological information has accumulated. Many scientists are now actively involved in research concerning Carex, and the recent and rapid growth of this research area suggests that a review of the subject will be of value, not only to the researchers involved, but also to the general botanist.On 16 June 1987, the Systematics and Phytogeography section of the Canadian Botanical Association/l'Association botanique du Canada hosted a symposium to review major aspects of Carex research and outline appropriate directions for future study in each area. We are pleased to offer the presented papers to a wider audience as a record of the first international symposium on the systematics and ecology of one of the largest and least well known genera of plants in the temperate regions of the world.
Anatomical aspects of the taxonomy of sedges (Carex, Cyperaceae)
Authors: Standley L. A.
Published: April 2011

Patterns of variation in the anatomy of achene epidermis and leaves were examined to assess the utility of anatomical characters in systematic and phylogenetic studies of Carex and the Cyperaceae. This study was based primarily on a review of the available literature. In addition, foliar anatomy of species in Carex sect. Phacocystis was investigated and patterns of variation within the section were analyzed using a centroid cluster algorithm. Nearly all genera and all sections of Carex for which data are available include species with single conical silica bodies in the achene epidermal cells as well as species with more elaborate, presumably derived, silica bodies. Similarly, most sections within Carex include species that have hypostomatous leaves with a single layer of bulliform cells and that lack papillae, as well as species with amphistomatous leaves, papillose epidermal cells, or multiple bulliform cells. Application of the "common equals primitive" in group criterion for determining evolutionary polarity indicates that single conical silica bodies and epapillose hypostomatous leaves are primitive character states in Carex. As both primitive and derived character states are widely distributed among sections, anatomical characters should not be generally applied as measures of similarity in phenetic approaches to classification but have potentially major importance in phylogenetic studies within and among sections.
Studies on the systematics of ectomycorrhizal fungi in axenic culture. II. The enzymatic degradation of selected carbon and nitrogen compounds
Authors: Hutchison Leonard J.
Published: April 2011

Ninety-six species of ectomycorrhizal fungi from 30 genera were grown on modified Melin–Norkrans agar where the carbon (glucose) or nitrogen (ammonium phosphate dibasic) supply was replaced by cellulose, lignin, pectin, lipid, amylose, gelatin, casamino acids, or urea. Ectomycorrhizal fungi did not appreciably degrade cellulose, lignin, or pectin. The remaining compounds were broken down by representatives of certain taxonomic groups. Lipase was produced by Amanita species, amylase by species of Amanita and Cortinarius, gelatinase by Piloderma, Thelephora, species of Lactarius section Dapetes, and some species of both Amanita and Cortinarius. Casamino acids were degraded by Laccaria, Hebeloma, and some Tricholoma species. Urease was detected in species of Hebeloma and Laccaria. The ability to enzymatically degrade selected carbon and nitrogen compounds have potential as taxonomic characters for the identification of isolates of ectomycorrhizal fungi. The significance of these results are also discussed in relation to the ecology of these fungi. Key words: ectomycorrhizal fungi, enzyme activity, cultures, identification, systematics.
New species of Koralionastes (Ascomycotina) from the Caribbean and Australia
Authors: Kohlmeyer Jan , Volkmann-Kohlmeyer Brigitte
Published: April 2011

Koralionastes giganteus Kohlm. & Volkm.-Kohlm. sp.nov. is described from subtidal coral slabs of back reefs of two small islands off the coast of Belize, Central America. Koralionastes violaceus Kohlm. & Volkm.-Kohlm. sp.nov. occurs on an island of the Great Barrier Reef, off the Queensland (Australia) coast, and is the first record of the genus outside of the Caribbean. All five Koralionastes species are associated with crustaceous sponges. Key words: Koralionastes, Koralionastes giganteus, Koralionastes violaceus, marine fungi, ascomycetes, corals, sponges.
Immunological discrimination between a sap-staining fungus and a biological control fungus
Authors: Luck Brian T. , Breuil Colette , Brown David L.
Published: April 2011

An enzyme-linked immunosorbent assay (ELISA) was used to detect a sap-staining fungus, Ophiostoma piceae, and a biological-control agent, Gliocladium roseum, grown in liquid culture and in wood. A polyclonal serum prepared against whole cell fragments from broken mycelia of O. piceae detected O. piceae in liquid culture at 0.25 μg dry weight/mL; however, there was moderate cross-reactivity with G. roseum. Antiserum adsorbed on G. roseum had almost no reactivity with G. roseum but still reacted strongly with O. piceae. The specificity of these sera was verified, and the antigenic sites were localized, by immunogold labeling and electron microscopy. These studies confirmed that the adsorbed serum could differentiate between G. roseum and O. piceae and showed that the cell wall was the most reactive cellular component. These results are discussed in relation to the development of immunological probes for the detection of sap-staining and biological control fungi. Key words: polyclonal serum, enzyme-linked immunosorbent assay, immunogold labeling, sap-staining and biological control fungi, electron microscopy.
Fossil seed cones of Fokienia (Cupressaceae) from the Paleocene Ravenscrag Formation of Saskatchewan, Canada
Authors: McIver E. E. , Basinger J. F.
Published: April 2011

Foliage bearing seed cones that are remarkably similar to those of extant Fokienia (Cupressaceae) have been recovered from early Paleocene sediments of the Ravenscrag Formation, southwestern Saskatchewan, Canada. The cones are borne in opposite pairs, are about 12.0 mm long and 10.0 mm wide, with 8–10 woody, decussate, peltate scales. Foliage branches oppositely and bears thin, flattened leaves in whorls of four. Although branching pattern and leaf morphology differ from that of modern Fokienia, similarity in seed cone structure allows assignment to this genus. These fossil remains indicate that cone structure comparable to modern Fokienia had evolved by the earliest Tertiary and has probably remained stable since. The vegetative remains indicate, however, that leaf and branch morphology has continued to evolve over this period of time (mosaic evolution), or that the diversity of morphological forms has in the past been greater in Fokienia and that extinction has limited this diversity. Such data reinforce the principle that seed cone structure should be the basis for identification of fossil Cupressaceae remains. Key words: Fokienia, Cupressaceae, Paleocene, fossil, seed cones, evolution.
Mating system and genetic structure of two populations of white spruce (Picea glauca) in eastern Newfoundland
Authors: Innes David J. , Ringius Gordon G.
Published: April 2011

Allozyme variation at four polymorphic enzyme loci (Pgi-1, Pgi-2, Pgm, Gdh) was used to study genetic variation and mating system in a sheltered (inland) and an adjacent exposed population (coast) of white spruce (Picea glauca (Moench) Voss) in eastern Newfoundland. Despite habitat differences, the two populations showed only small differences in allele frequency for the maternal trees, their progeny, and the estimated pollen pool. Three of the four single-locus estimates of outcrossing rate (ts) for the inland population were significantly less that t = 1.00, with an average value of ts = 0.81. Two of the four single-locus estimates of outcrossing rate in the coast population were significantly less than t = 1.00 and the average for the four loci was 0.71. The multilocus estimates of outcrossing rate (tm) for the inland and coast populations were 0.76 and 0.70, respectively, and both estimates were significantly less than t = 1.00. This level of selfing is higher than that observed for most other conifer species. Key words: genetics, mating system, population genetics, outcrossing, selfing, white spruce.
Plant zonation in a brackish tidal marsh: descriptive verification of resource-based competition and community structure
Authors: Pidwirny Michael J.
Published: April 2011

This study examined the hypothesis that the zonal patterns of dominant species in brackish tidal marshes may be explained by resource competition for soil nitrogen and light. This hypothesis was tested by analyzing abiotic and biotic field data collected from a brackish tidal marsh located at Brunswick Point, British Columbia. Biotic data revealed that this tidal marsh is dominated by two species that occupy distinct separate zones correlated to marsh elevation. In particular, sites whose elevation was from −0.80 to 0.20 m (geodetic datum) were dominated by Scirpus americanus, while sites with an elevation 0.20 m were dominated by Carex lyngbyei. Analysis of the relationships between measured variables indicated that total species biomass, species height, and total soil nitrogen were all positively correlated to sample site elevation. Further, the availability of light at the soil surface was found to be negatively correlated to plant biomass and site elevation. These results may suggest that S. americanus is dominant in the low marsh because it is a better competitor for soil nitrogen. Carex lyngbyei may be competitively dominant in the high marsh because its greater biomass and height make it a superior competitor for light. Key words: competition, light, nitrogen, tidal marshes, zonation.
Seasonally dependent formation of protein-storage vacuoles in the inner bark tissues of Salix microstachya
Authors: Greenwood John S. , Demmers Cobi , Wetzel Suzanne
Published: April 2011

The inner bark tissues of temperate hardwoods often act in the temporary storage of reduced nitrogen as protein during the overwintering period. Electron microscopic studies reported here demonstrate the analogy between the protein-storage vacuoles of the inner bark tissues and protein bodies in seeds. Development of these organelles parallels that of protein body formation seen in many dicotyledonous seeds. Coincident with the synthesis and sequestering of specific proteins, the large central vacuoles of the phloem parenchyma cells are slowly replaced over a 3- to 4-week period with numerous smaller protein-storage vacuoles (protein bodies). These arise via the subdivision of the larger vacuole and subsequent filling of the smaller vacuoles with protein. During this process there is a proliferation of both free ribosomes and rough endoplasmic reticulum in the ground cytoplasm. Stacks of rough endoplasmic reticulum are present in the peripheral cytoplasm and surround the smaller vacuoles as proteinaceous material is deposited. Golgi complexes, although not numerous, are present in the ground cytoplasm during the filling of the protein storage vacuoles. Key words: protein-storage vacuoles, protein body development, Salix microstachya, hardening, nitrogen storage, dormancy onset.
The role of waterlogging and sand accretion in modulating the morphology of the dune slack plant Scirpus americanus
Authors: Seliskar Denise M.
Published: April 2011

Scirpus americanus Pers., a major dune slack plant in coastal sand dune ecosystems, differs in height along transects ranging between the lowest and highest elevational areas of slacks located along the coast of Delaware, U.S.A. Using reciprocal transplant and common garden experiments, results suggest that environmental factors rather than hereditary traits are more important in accounting for the differences in plant morphology expressed in the field. Dune slack plants are exposed to stresses of waterlogging and sand accretion in their natural environment. In controlled greenhouse experiments waterlogging was shown to inhibit stem growth and cause an increase in aerenchymatous tissue, whereas periodic sand deposition caused an increase in the plant height of Scirpus.
Morphological variation, frequency, and distribution of bisporangiate strobili in Picea mariana
Authors: Caron G. E. , Powell G. R.
Published: April 2011

Investigations of strobilus production over 4 successive years in 8- to 18-year-old plantations of Picea mariana (Mill.) B.S.P. revealed infrequent occurrence of bisporangiate strobili. However, such strobili were borne only at, or shortly after, the time that the tree first initiated reproductive activity, and mostly at 10 years of age. They were borne terminally or distally on shoots in the microsporangiate zone of the crown and mostly on shoots located near the megasporangiate zone. All bisporangiate strobili had microsporophylls proximally and bracts and ovuliferous scales distally. The proportions of these elements varied and strobili with more microsporophylls than bracts generally abscised after pollen shedding. Some strobili with more bracts than microsporophylls and with a thick curved axis remained on trees and had normal ovuliferous scales but shrivelled microsporophylls and microsporangia.
Nutritional regulation of synthetic lignin (DHP) degradation by the selective white-rot fungus Phlebia (Merulius) tremellosa: effects of glucose and other cosubstrates
Authors: Reid Ian D. , Deschamps Alain M.
Published: April 2011

Phlebia tremellosa is a white-rot fungus which selectively degrades lignin, i.e., its ratio of lignin degradation to carbohydrate degradation during wood decay is higher than that of "simultaneous" white rots. Its need for a cosubstrate to support lignin degradation, and the effect of glucose supply on rate and extent of lignin metabolism, were examined in a synthetic, nitrogen-limited medium. Lignin metabolism by P. tremellosa, like simultaneous white rots, requires a cosubstrate. Glucose partially represses lignin degradation, but it is metabolized to extracellular intermediates, including ethanol. Subsequent utilization of ethanol as energy source supports rapid lignin degradation. Phlebia tremellosa grows well with cellulose, glucose, xylose, ethanol, or lactate as sole carbon (energy) source, and more slowly with glycerol or methanol. It appears unable to use kraft lignin, ferulate, vanillin, or acetate as sole carbon source. Cellulose, glycerol, and ethanol efficiently supported degradation of ring-labelled lignin to CO2, whereas glucose, xylose, and lactate were less efficient cosubstrates; methanol did not support lignin degradation. A relationship between tricarboxylic acid cycle operation and metabolism of lignin ring carbons to CO2, is suggested. Key words: lignin biodegradation, cosubstrate, glucose, ethanol, selectivity.
Nutritional regulation of synthetic lignin (DHP) degradation by Phlebia (Merulius) tremellosa: effects of nitrogen
Authors: Reid Ian D.
Published: April 2011

Supplementary nitrogen added to cultures of Phlebia tremellosa in a nitrogen-limited synthetic medium delayed the appearance of lignin-degrading activity. It also accelerated the consumption of the carbon (energy) source by the cultures, decreasing the amount of cosubstrate available to support lignin biodegradation. Ammonium chloride, glutamate, albumin, and yeast extract all had similar effects, with small differences in the timing and extent of the lignin degradation that they allowed. Key words: lignin biodegradation, cosubstrate, nitrogen, selectivity.
Polyphenolics of phylogenetic and biosynthetic interest from the fern Cystopteris fragilis
Authors: Imperato Filippo
Published: April 2011

Four xanthones (mangiferin, isomangiferin, their aglycone 1,3,6,7-tetrahydroxyxanfhone, and 3-O-mefhylisomangiferin) have been isolated from the fern Cystopteris fragilis Bernh. The cooccurrence of the first three of these compounds suggests that C-glycosylation is the last step in the biosynthesis of C-glycosylxanthones. 3-O-Methylisomangiferin has previously been reported only from Mangifera indica, an angiosperm. In addition to the above substances, a C-glycosylflavonoid (6,8-di-C-glucosylapigenin, also known as vincenin-2) and two sulphate esters of 1-caffeylglucose (1-caffeylglucose 6-sulphate and 1-caffeylglucose 3-sulphate) have been isolated from C. fragilis. Key words: xanthones, mangiferin, Cystopteris fragilis, C-glycosylation.
Floral mutants in tomato: development, physiology, and evolutionary implications
Authors: Sawhney V. K.
Published: April 2011

Developmental and experimental studies on two floral mutants of tomato (Lycopersicon esculentum) are presented. These studies have provided insights into the gene-regulated physiological, biochemical, and structural processes that affect flower morphology. In the stamenless-2 (sl-2/sl-2) mutant, plant growth regulators and temperature conditions affect the development of stamens, and these effects are mediated through changes in proteins, including some specific enzymes. Stamen primordia can be induced to form either normal stamens or carpels, which suggests the possibility of another mechanism by which unisexuality may have evolved. In the solanifolia (sf/sf) mutant, the nonfusion of stamens and carpels is associated with an increase in the size of the apex and the number of organs. The fusion of these organs is also affected by plant growth regulators and temperature conditions. It is proposed that during the course of evolution plants with small floral apices that produce few stamens and carpels were selected and that the reduction in apex size was achieved by mutations that affect endogenous plant growth regulators. Key words: floral mutants, Lycopersicon esculentum, plant growth regulators, temperature, tomato, evolution.
Fossil Fokienia (Cupressaceae) from the Paleocene of Alberta, Canada
Authors: McIver E. E.
Published: April 2011

Fossil foliage bearing seed cones of Fokienia ravenscragensis McIver & Basinger (Cupressaceae) from the early Paleocene of Alberta, Canada, provides information about the species not available previously. This cedar, first described from the Paleocene Ravenscrag Formation, Saskatchewan, bears seed cones remarkably similar to extant Fokienia. Fossils from Alberta indicate that the fertile axis bore up to three pairs of seed cones in opposite pairs at successive nodes. Pollen cones and pollen, previously unknown, are typical for the Cupressaceae. Pollen cones bear decussate microsporophylls with deltoid distal lamina and globose abaxial sporangia; pollen is ellipsoidal to circular in outline, the wall psilate with irregularly spaced small gemmae. Cupressaceous seeds associated with seed and pollen cones may belong to the taxon, but they are not identical to those of extant Fokienia, differing mainly in wing morphology. The architecture of the cone-bearing axis of this fossil species is unlike any extant member of the Cupressaceae. Fossil data now available from this and other taxa allow speculations on the ancestry of Fokienia and other related genera. Key words: Fokienia, Cupressaceae, evolution, Tertiary, Paleocene, fossil, seed cones, pollen cones, pollen.
Ultrastructural organization of Rhizophlyctis harderi zoospores and redefinition of the type 1 microbody – lipid globule complex
Authors: Powell Martha J. , Roychoudhury Sonali
Published: April 2011

Because ultrastructural features of zoospores are considered primary characters in Chytridiomycete systematics, computer-aided three-dimensional reconstructions of serial sections were used to analyze zoospore fine structure of Rhizophlyctis harderi, a questionable member of the genus Rhizophlyctis. A secondary centriole was parallel to the kinetosome, but the nucleus was not structurally or spatially associated with the kinetosomes. Mitochondria and cisternae associated with vesicles bounded a ribosomal aggregation in which the nucleus was partially embedded. The peripheral cytoplasm between the plasma membrane and ribosomal aggregation contained α-glycogen particles, vacuoles with osmiophilic globules, vesicles with clear matrices, and vesicles with electron-dense cores. A new, compound form of microbody – lipid globule complex (MLC) was identified. This type of MLC incorporated posteriorly located lipid globules associated with rumposomes and anteriorly located lipid globules associated with simple cisternae, microbodies, and highly branched mitochondria. Based on these and other recent observations, the concept of the type 1 MLC was redefined. Sources for variation in ultrastructural features of zoospores are discussed. Zoospore ultrastructure of R. harderi is different from that described for other chytrid zoospores. Key words: Chytridiomycetes, microbody – lipid globule complex, Rhizophlyctis, taxonomy, ultrastructure, zoospore.
Improved media for testing the mating reaction and genetic complementation of Ustilago hordei
Authors: Martinez-Espinoza Alfredo D. , Dugan Karla J. , Bjarko Michael E. , Sherwood John E.
Published: April 2011

The sexual cycle of Ustilago hordei, which results in the formation of teliospores, requires growth on its barley host for completion. However, the early steps of mating, including conjugation and the formation of dikaryotic mycelium, can occur on artificial media. The addition of activated charcoal to a variety of media enhanced the stability and intensity of the mating reaction as measured by mycelium formation. The incubation time at which the strongest mating reaction occurred was also reduced. The dikaryotic nature of the mycelia that resulted from mating on charcoal-containing media was confirmed by fluorescence microscopy. Complementation assays using minimal medium containing activated charcoal demonstrated allelism of mutations in auxotrophic sporidial strains of opposite mating type. The ease and reliability of this mating test allow for rapid identification of the mating type of unknown isolates and progeny of crosses, as well as providing a dependable procedure for performing complementation tests. Key words: barley, covered smut, Hordeum vulgare, mating type.
Flow cytometric characterization of microspore development in Brassica napus
Authors: Fuchs K. , Pauls K. P.
Published: April 2011

Flow cytometry was found to be sensitive to change in the physical characteristics of developing Brassica napus microspores. By measuring forward angle (10° – 19°) light scatter (FALS) and log 90° light scatter (L90LS) several stages of microspore development were characterized in small (1.5 mm to 2.5 mm), medium (2.5 mm to 3.5 mm), and large (3.5 mm to 4.5 mm) buds. Cell sorting was used to identify the types of cells that made up the subpopulations in two parameter plots of FALS versus L90LS including tetrad, translucent, trilobate, round, and oval microspores. Microspore development was found to be synchronous in the variety that was studied (‘Topas’) since only a few stages were found in each bud-size category. The study defined the normal process of pollen ontogeny in terms of the changes in light scatter that the cells underwent and demonstrated that flow cytometry is a useful method for analyzing this process. Key words: flow cytometry, Brassica napus, microspores, pollen, light scatter.
Germination and development of attachment structures by conidia of aquatic Hyphomycetes: a scanning electron microscope study
Authors: Read S. J. , Moss S. T. , Jones E. B. G.
Published: April 2011

Conidia of 10 species of aquatic Hyphomycetes were examined at the scanning electron microscope level. Mucilage was produced at the tips of the arms of tetraradiate conidia and also at conidium–substratum contact points of the conidia of non-tetraradiate species. Hyphal sheaths were ubiquitous. Species that formed appressoria on artificial substrata also formed appressoria readily on wood. All appressoria were surrounded by mucilage. Additionally, conidia of Tumularia aquatica produced protoappressorium-like structures on the wood. There were marked textural differences between the mucilages on different structures that may also indicate differences in their composition. Key words: aquatic Hyphomycetes, appressoria, attachment, mucilage, scanning electron microscopy.
Modifications in the alkane composition of cuticular waxes from spruce needles (Picea abies) and ivy leaves (Hedera helix) exposed to ozone fumigation and acid fog: comparison with needles from declining spruce trees
Authors: Kerfourn C. , Garrec J. P.
Published: April 2011

Our study on the chemical composition of cuticular waxes showed that the configuration of alkane homologues, in needles from declining spruce trees as well as in artificially polluted ivy leaves and spruce needles, presented a significant shift towards lower molecular weight chains. On the contrary, in both materials ageing was characterized by increasing chain lengths. This work emphasizes the importance of the short and long carbon chains as representative parameters of chemical alteration of cuticular waxes. As far as alkanes are concerned, pollutants may change cuticular wax composition by acting on sites of their metabolic biosynthesis rather than through a direct passive chemical contact effect. Key words: Picea abies, Hedera helix, forest decline, ozone, acid fog, waxes, cuticles, alkanes.
Distribution and frequency of a gene for resistance to white pine blister rust in natural populations of sugar pine
Authors: Kinloch Jr. Bohun B.
Published: April 2011

The gametic frequency of a dominant allele (R) for resistance to white pine blister rust, a disease caused by an introduced pathogen (Cronartium ribicola), in natural populations of sugar pine was estimated by the kind of leaf symptom expressed after artificial inoculation of wind-pollinated seedlings from susceptible seed–parent genotypes (rr). Gene frequency increased clinally from near 0 in the southern Cascade Range to 0.08 in the southern Sierra Nevada, but it was not correlated with any major climatic gradient. Because R expresses a typical hypersensitivity response to pathogenesis, it has probably always functioned in disease resistance. A candidate pathogen for this function is C. occidentale, cause of pinyon blister rust, and a close relative of C. ribicola. Increase in allele frequency was positively associated with the proximity of sugar pine to single-leaf pinyon pine populations. Although sugar pine is not presently a natural host of pinyon rust, R may be a relict gene that protected sugar pine from this endemic pathogen in recent geologic epochs, when both pines are known to have been more intimately associated. Key words: Cronartium ribicola, genetic resistance, Pinus lambertiana, population genetics.
Les organes de reproduction de l'ascomycète Phaeosphaeria (Leptosphaeria) nodorum et de sa forme asexuée Septoria nodorum
Authors: Halama P. , Parguey-Leduc A. , Lacoste L.
Published: April 2011

The reproductive organs of one of the pathogens responsible for the septoria diseases of wheat were studied from cultures. There are two types of pycnidia for the asexual stage (one belongs to Septoria nodorum Berk. (=Stagonospora nodorum (Berk.) Castellani & Germano); the other is microconidial) and pseudothecia for the teleomorph: Phaeosphaeria nodorum (E. Müller) Hedjaroude (=Leptosphaeria nodorum E. Müller). The latter are differentiated from glomerular primordia, and their development is typical of an ascolocular pyrenomycete, with a perilocular layer generating descending pseudoparaphyses and periphyses lining the ostiolar cavity. The asci, with a "Jack-in-the-box" dehiscence, are bitunicate. Key words: Phaeosphaeria nodorum, Leptosphaeria, ontogeny and structure, pseudothecia, pycnidia.
Involvement of the proton pump and proton conductance change in the wave of depolarization induced by wounding in Bidens pilosa
Authors: Julien J. L. , Frachisse J. M.
Published: April 2011

The role of protons in the slow wave of depolarization induced by wounding in Bidens pilosa L. was studied by means of voltage measurements performed under differing extracellular conditions. The degree of depolarization caused by an extracellular pH acidification from 7 to 4 was different when performed either in the resting conditions or 20 min after eliciting the slow wave. In the presence of cyanide, a heat stimulation still induced a slow wave, the amplitude of which was reduced to 42% of the control. While cyanide remained in the perfusing medium, the membrane did not repolarize. An extracellular pH change from 7 to 4 in the presence of cyanide induced a higher depolarization in the resting conditions than 20 min after eliciting a slow wave. Furthermore, when pumps were previously stimulated either by acid loading or by fusicoccin, the amplitude of the slow wave was increased. We thus propose that the slow wave was largely dominated by a transient "switch off” of the proton pump and we discuss the possible involvement of proton conductance change during the slow wave. Key words: Bidens pilosa L., membrane potential, proton conductance, slow wave of depolarization, wounding.
Mediterranean evergreen oak diversity: morphological and chemical variation of acorns
Authors: Afzal-Rafii Zara , Dodd Richard S. , Pelleau Yvonne
Published: April 2011

Acorns of mediterranean evergreen oak were collected from eight ecogeographically contrasting localities in Italy and Spain. Biometrical analysis of acorns and their cupules showed much greater variation among Spanish populations, encompassing the variation in Italy. The Spanish population at El Pardo, considered the type locality for Quercus rotundifolia, separated from all others. Multivariate analyses of the chemical data indicated, on the one hand, separation of Spain from Italy, and on the other hand, a separation of interior Spanish populations from coastal populations. The importance of lipid composition in the former separation may reflect genetic differentiation between these two origins. Coastal populations were closer to Italian and we suggest were a zone of introgression and hybridization between Quercus ilex and Q. rotundifolia and probably also Quercus coccifera at Bonete Albacete. Key words: Quercus ilex, Quercus rotundifolia, biometry, diversity, chemistry, ecogeography.
Distribution of biomass and nitrogen among plant parts and soil nitrogen in a young Alnus incana stand
Authors: Huss-Danell Kerstin , Ohlsson Helene
Published: April 2011

Grey alder, Alnus incana (L.) Moench, was inoculated with the local source of Frankia and planted in nitrogen-poor soil in northern (63.8°N, 20.3°E) Sweden. Each alder root system was enclosed in a cylinder that served as an open-ended cuvette for nitrogenase activity measurements. The alders grew well, especially during the 2nd year of the study. The final leaf area in each season was more closely related to total alder biomass than final height of alders. The alders lost 17% of their total dry mass as leaf litter each year. This corresponded to 33 g dry mass and 0.67 g N per alder during the 2nd year. During the 2 years the soil N increment was 0.52 g N per alder. Leaf litter N and the increase in soil N corresponded to 27 and 17%, respectively, of the N2 fixed in the 2 years. Already at a young age, N2-fixing A. incana can apparently contribute to an improved fertility of N deficient soils. Key words: aboveground biomass, Alnus incana, belowground biomass, leaf litter, nitrogen content, soil N increment.
Seasonal and temperature effects on mycorrhizal activity and dependence of cool- and warm-season tallgrass prairie grasses
Authors: Bentivenga S. P. , Hetrick B. A. D.
Published: April 2011

Previous research on North American tallgrass prairie grasses has shown that warm-season grasses rely heavily on vesicular–arbuscular mycorrhizal symbiosis, while cool-season grasses are less dependent on the symbiosis (i.e., receive less benefit). This led to the hypothesis that cool-season grasses are less dependent on the symbiosis, because the growth of these plants occurs when mycorrhizal fungi are inactive. Field studies were performed to assess the effect of phenology of cool- and warm-season grasses on mycorrhizal fungal activity and fungal species composition. Mycorrhizal fungal activity in field samples was assessed using the vital stain nitro blue tetrazolium in addition to traditional staining techniques. Mycorrhizal activity was greater in cool-season grasses than in warm-season grasses early (April and May) and late (December) in the growing season, while mycorrhizal activity in roots of the warm-season grasses was greater (compared with cool-season grasses) in midseason (July and August). Active mycorrhizal colonization was relatively high in both groups of grasses late in the growing season, suggesting that mycorrhizal fungi may proliferate internally or may be parasitic at this time. Total Glomales sporulation was generally greater in the rhizosphere of cool-season grasses in June and in the rhizosphere of the warm-season grasses in October. A growth chamber experiment was conducted to examine the effect of temperature on mycorrhizal dependence of cool- and warm-season grasses. For both groups of grasses, mycorrhizal dependence was greatest at the temperature that favored growth of the host. The results suggest that mycorrhizal fungi are active in roots when cool-season grasses are growing and that cool-season grasses may receive benefit from the symbiosis under relatively cool temperature regimes. Key words: cool-season grasses, tallgrass prairie, vesicular–arbuscular mycorrhizae, warm-season grasses.
Bird dispersal of fruits of species introduced into eastern North America
Authors: White Douglas W. , Stiles Edmund W.
Published: April 2011

We compared bird use of fruits of introduced and native plant species to explore the roles of coevolution, ecological fitting, and chance in shaping seed dispersal interactions. Of 45 bird-dispersed species recorded at three sites in central New Jersey, 15 (33%) were nonnative. In fall samples from seed traps and fecal droppings, introduced species accounted for 0.4–14% of fruit biomass overall and 3 – 30% of the biomass of low-quality fruits. Although absolute fruit use declined from fall to winter, relative use of introduced species increased seasonally to as high as half of winter fruit biomass. Heavy use of non-native fruits appears recent; introductions accounted for only 2% of plant species occurrences in fall and winter records of stomach contents for nine passerine species in New England and mid-Atlantic states between 1881 and 1950. Introduced fruits with fall maturation, low-quality pulp, and high durability now rival native species in fruit diets of birds in late fall and winter. The success of introductions demonstrates coadaptation through ecological fitting of preadapted partners; nevertheless, the predominant use of introduced fruits after peak bird migration suggests that introduced fruits may be less well matched to local dispersal opportunities than native ones. Key words: birds, coevolution, fruits, introductions.