bluuebunny/crossref_metadata_2025 huggingface dataset:
Stilbotulasnella: a new genus in the Tulasnellaceae
Authors: Bandoni R. J. , Oberwinkler F.
Published: April 2011

A new genus, Stilbotulasnella, with the single species Stilbotulasnella conidiophora, is described from material collected in Hawaii. The distinguishing features of the genus are (i) copious production of blastic conidia; (ii) scattered tulasnellaceous basidia; (iii) germination of conidia and basidiospores by budding; (iv) dolipore septa without parenthesomes. Conidia of S. conidiophora are blastic annelidic, dikaryotic; they are produced on mononematous conidiophores or conspicuous synnematous to sporodochial conidiomata. The basidiospores germinate by repetition, by germ tube, or by budding.
Solar radiation attenuation in a hillside jack pine forest
Authors: Whitfield D. W. A. , Mehlenbacher L. A. , Labine C.
Published: April 2011

A modelling technique for penetration of solar radiation into clumped vegetation canopies is described. It combines Monte-Carlo simulation to determine ray pathlengths through individual plant canopy envelopes with exponential attenuation along these rays. The technique is applied to a hillside forest of randomly located and sized jack pine trees. Scattering effects are incorporated and the model output is compared with field measurements. The results depend on the shape of the tree outline. Attenuation is less rapid with downward cumulative leaf area index than in a randomly dispersed canopy.
Patterns of dry-matter distribution in transplanted populations of Trifolium repens and its bearing on ecological interpretations
Authors: Turkington Roy , Maze Jack
Published: April 2011

An experiment was carried out to examine the degree of plasticity of various plant parts in Trifolium repens L. when transplanted from 12 widely different sites to a common garden. Plasticity was structure specific. Inflorescence production displayed the most plastic response after transplanting; leaf and root production were less plastic. Stolon production did not show a plastic response to transplanting but did show significant between-plant variation. These responses may be explained by past selection pressures, acting to maintain the structure which is most important for survival under conditions which have deleterious effects on plant growth. An alternate interpretation suggests that the range of responses may also be explained by different developmental patterns.
Relationship of leaf parameters with genetic ozone insensitivity in selected Phaseolus vulgaris cultivars
Authors: Hucl P. , Beversdorf W. D. , McKersie B. D.
Published: April 2011

The relationship of ozone-induced foliar injury (ozone sensitivity) with several leaf characteristics including stomatal frequency, stomatal closure in the presence of ozone (O3), and trichome densities (abaxial and adaxial) was evaluated for a diverse group of Phaseolus vulgaris L. cultivars. Differences were observed among cultivars for ozone sensitivity and leaf parameters including stomatal frequency, trichome density, and stomatal closure in the presence of O3. Although significant (P ≤ 0.05) differences among the cultivars for stomatal frequency and trichome densities existed, no consistent pattern between insensitive and sensitive cultivars was observed. Ozone-sensitive genotypes responded to 40 parts per hundred million O3 with similar or greater stomatal closure than the more insensitive genotypes, indicating that stomatal closure was not a primary mechanism for O3 insensitivity among the cultivars evaluated.
Ultrastructural and cytochemical changes in the wall of a vesicular–arbuscular mycorrhizal fungus during symbiosis
Authors: Bonfante-Fasolo Paola , Grippiolo Roberto
Published: April 2011

During the various stages of the symbiotic association of the vesicular–arbuscular mycorrhizal (VAM) fungus Glomus fasciculatus (Thaxter) Gerd, et Trappe with the roots of Vitis vinifera L. cv. Barbera, the hyphal wall undergoes marked modifications as follows: (i) a gradual thinning out, from the extraradical hyphae to the intraradical hyphae; (ii) changes in its ultrastructural architecture, in that the wall consists of stacked lamellae in both the extraradical and coiled hyphae occurring in the outer layers of the cortical parenchyma, whereas it is monostratified in the intercellular and arbuscular hyphae occurring in the inner parenchymal layers; and (iii) different responses to cytochemical reactions. The protein and polysaccharide components, though consistently present in the fungal wall at all stages, vary in their staining characteristics after the PATAg and Swift procedure and in their responses to alkali extraction, suggesting a gradual simplification of the wall components from the extraradical hyphae to the intraradical ones.
Blue-stain fungi in xylem of lodgepole pine: a light-microscope study on extent of hyphal distribution
Authors: Ballard R. G. , Walsh M. A. , Cole W. E.
Published: April 2011

In midsummer mountain pine beetles emerge from lodgepole pine trees and fly to unattacked trees. While chewing vertical egg galleries in the inner bark of the tree, they inoculate into it a blue-stain fungus complex. Initially, the fungi are confined to the beetle frass of the egg gallery, but they soon grow into the sapwood. The fungi spread radially via the parenchyma of the xylem rays. Once established in the xylem rays, fungal hyphae move into the tracheids of the axial water-conducting system. Here they occlude bordered-pit pairs and occasionally the entire lumen of the cell. Fungal hyphae also attack and destroy resin-duct epithelial cells. This may result in release of resin into surrounding tissues. Destruction of storage and water-conducting tissues in the tree trunk is detrimental to renewed shoot tip expansion the following spring.
Mycorrhizal status of Rhododendron spp. in commercial nurseries in Rhode Island
Authors: Moore-Parkhurst S. , Englander L.
Published: April 2011

Rhododendron cultivars English Roseum and Nova Zembla were surveyed for the presence of ericoid mycorrhizae at various stages of propagation in four commercial nurseries in Rhode Island. Ericoid mycorrhizae developed in both cultivars in the rooting bench and were retained throughout all phases of commercial production in the nurseries surveyed. Significant differences in levels of mycorrhizal infection were observed among nurseries, among propagation stages (more in the rooting and field stages than in the transplant and container stages), and between cultivars (greater mycorrhizal infection occurred in 'English Roseum'). It is postulated that variability in nursery environments and plant production practices influences the mycorrhizal status of commercially grown Rhododendron spp.
Regulation of nicotine biogenesis. 3. Biochemical basis of increased nicotine biogenesis by urea in tissue cultures of tobacco
Authors: Ravishankar G. A. , Mehta A. R.
Published: April 2011

Floral bud callus of Nicotiana tabacum L. var. Anand-2 could be grown on Murashige and Skoog medium with 10 mM urea as sole nitrogen source. Urea-treated tissues showed elevated nicotine content over the control. Activities of phenylalanine aminotransferase and tyrosine aminotransferase did not show close correspondence with growth or nicotine synthesis, whereas ornithine aminotransferase (OAT) activity exhibited correlation with nicotine biogenesis. Urea-treated callus showed higher OAT activity than the control. The activity of ornithine transcarbamylase (OTC) showed inverse correlation with nicotine synthesis. OTC and arginase activities were suppressed in urea-treated tissues. The implication of the results is discussed.
Approche taximétrique des hyménochétacées porées d'Europe (champignons, aphyllophorales)
Authors: Fiasson Jean-Louis , David Alix
Published: April 2011

Taximetric analysis of micro- and macro-scopical features of 37 European polyporous Hymenochaetaceae (basidiocarps and mycelia) did not support current generic concepts; actually these are based on mitism (hyphal systems), a criterion currently shown as not well suited for this group of fungi. Nevertheless, this preliminary study allows firm conclusions only at the level of some infrageneric regroupings (especially within Phellinus), the naturalness of which is supported by other data.
Étude morphologique, anatomique et ultrastructurale d'endomycorhizes synthétiques d'Erica carnea
Authors: Duclos J. L. , Pépin R. , Bruchet G.
Published: April 2011

Endomycorrhizae were synthesized between Erica carnea and a fungus isolated from E. vagans. Inoculated and non-inoculated plants were grown for 6 months under controlled conditions. Inoculation provokes an important stimulation of the growth and flowering of E. carnea. Under the experimental conditions reported herein, the mycorrhizae formed during the 1st month remained localised and, after 6 months, the roots usually were not colonized by the fungus. It seems probable that colonization of the whole root system requires a growth substrate that favours mycelial growth.Macroscopic and microscopic characters of the mycorrhizae obtained were studied using light and scanning (SEM) and transmission (TEM) electron microscopy. The hyphae of the responsible fungus exhibit simple septa and Woronin bodies (ascomycetes). The intracellular hyphae are characterised by the abundance of lipid globules and the presence in SEM of electron-dense granules in the vacuoles. These hyphae are wrapped in a network of fibrils particularly at the penetration points but also observed on external hyphae. These mycorrhizae seem to survive for approximately 1 month only. The importance of the inoculum as nutritional source must not be neglected since similar stimulation of the plants was also produced by inoculation with an autoclaved slurry of mycelium. We suggest that not only mycorrhizal but also saprophytic rhizosphere fungi free, by simple autolysis of their mycelia, elements that are assimilable by the plant and doubtless play a role in the mineral nutrition of the Ericaceae.
Colonizing ability in the Echinochloa crus-galli complex (barnyard grass). II. Seed biology
Authors: Barrett Spencer C. H. , Wilson Blake F.
Published: April 2011

Comparisons of some seed parameters of two taxa of barnyard grass (Echinochloa crus-galli complex) were made in an effort to understand differences in habitat preference and colonizing ability. The taxa were E. crus-galli var. crus-galli, a cosmopolitan weed of wet, disturbed ground and E. crus-galli var. oryzicola, a crop mimic restricted to rice fields. In California, where all seed collections originated, the two taxa are ecologically differentiated within the rice-field ecosystem. Echinochloa crus-galli var. crus-galli is a weed of paddy banks and shallow water around the periphery of rice fields whereas E. crus-galli var. oryzicola is found primarily within permanently flooded rice fields. A survey of seed weight in 10 populations of each of the two taxa demonstrated that seeds of E. crus-galli var. oryzicola were on the average two to three times heavier than those of E. crus-galli var. crus-galli. Differences in weight were reflected in the buoyancy characteristics of fresh seeds of the two taxa. Approximately 50% of E. crus-galli var. crus-galli seeds remained afloat after 4–5 days in water whereas during the same period over 95% of the seeds of E. crus-galli var. oryzicola had sunk. Germination tests on 9- and 18-month-old seeds of 18 populations of E. crus-galli var. crus-galli and 11 populations of E. crus-galli var. oryzicola revealed significant differences between the taxa in the number of germinating seeds. The decay of dormancy in E. crus-galli var. oryzicola was more rapid than in E. crus-galli var. crus-galli following dry storage and burial in soil. The difference results in the greater germination synchrony of the crop mimic in comparison to the widespread weed. Emergence of seedlings from saturated and flooded soils was compared in the two taxa. In all treatments E. crus-galli var. oryzicola exhibited significantly greater levels of seedling emergence. The differences may explain changes in abundance of the two taxa in California rice fields, following the introduction of permanent flooding as a weed control practice, as well as their current microdistribution within the rice-field ecosystem.
A comparative account of cyst coat ontogeny in saprophytic and fish-lesion (pathogenic) isolates of the Saprolegnia diclina – parasitica complex
Authors: Beakes Gordon
Published: April 2011

The ultrastructural development of encystment vesicles (formerly bar bodies) and the outer cyst coat has been examined in primary and secondary spores of a range of isolates of Saprolegnia, mostly from the S. diclina – parasitica complex, of both saprophytic and fish-lesion origin. The development of both primary encystment vesicles (PEVs) in zoosporangia and secondary encystment vesicles (SEVs) in primary cysts appears essentially similar. The vesicles are probably derived from the rough endoplasmic reticulum system. The tubular primary spines and solid secondary boathooks seem to form autonomously within the vesicle matrix. Upon settling all of the preformed encystment vesicles are liberated from the zoospores to give rise to an electron-dense, amorphous, outer cyst coat, in which the spines are embedded. Fish-lesion isolates of S. parasitica have longer tubules on their primary cysts than saprophytic isolates and have distinctive bundles of long (<10 μm) boathooks on their secondary cysts compared with the single short (< 1.0 μm) boathooks typical of the saprophytes. However, even in fish-lesion isolates considerable variation in SEV and boathook sizes was observed. Staining by the Thiéry procedure revealed a high concentration of polysaccharidelike material with both the encystment vesicle cortex layer and spines, although treatment with various glucanases and proteases failed to digest either component. Spherical fibrous vesicles also appear in primary cysts and their contents are partially removed by protease digestion. These appear morphologically similar to the glycoprotein adhesive vesicles described in other oomycetes and appear to be discharged by secondary zoospores. The complex encystment apparatus in Saprolegnia is compared with that described in other oomycete and chytridiomycete fungi and the possible phylogenetic significance discussed. The role of the long boathook spines in relation to the infection of fish is also considered.
A new predatory hyphomycete capturing bdelloid rotifers in soil
Authors: Tzean S. S. , Barron G. L.
Published: April 2011

Cephaliophora navicularis, a hyphomycete capable of capturing bdelloid rotifers by using specialized adhesive pegs, is described as new. Canoe-shaped conidia are produced synchronously on ovoid- to club-shaped ampullae that arise more or less directly from the vegetative hyphae. In the presence of rotifers conidia develop short, adhesive appendages by which they attach to the host cuticle. After adhesion, germination and penetration occur and tortuous assimilative hyphae develop in the host. Vegetative hyphae from parasitized rotifers break out to the exterior and produce adhesive pegs which catch additional rotifers.
The structure and composition of a wooded urban ravine system
Authors: Carleton T. J. , Taylor S. J.
Published: April 2011

Fifty wooded ravine-slope stands in the Highland Creek valley system, Scarborough, Ont., were sampled for tree, sapling, shrub, and herbaceous vegetation by using plotless methods. In addition some soil characteristics were measured or estimated. Woody species were ordinated as stem size classes, using detrended correspondence analysis (DCA). Results indicated a strong trend along the first axis from pioneer species, typical of disturbed sites, through to shade-tolerant species typical of undisturbed forests. This pattern suggests that secondary succession is actively occurring in the woodland complex. However, little or no evidence of a self-regenerating "climax" woodland was apparent. Understorey vegetation, comprising 184 species in 48 of the stands, was also ordinated by DCA. These same data were subject to two-way indicator species analysis (TWINSPAN), a divisive clustering procedure. The ordination showed a distinctive separation along the first axis of wide stands from narrow stands with at least one edge exposed to full sunlight. The first division by TWINSPAN also segregated wide from narrow stands, listing those species which could be used as indicators of the degraded woodland condition. This results through stand isolation from neighbouring woodland and (or) increased lateral illumination. Furthermore, TWINSPAN indicated those woodland species under threat of local extinction in narrow, isolated stands. Compositional variation along the second DCA axis maximally discriminated among stands of the narrow, isolated group, although a clear underlying gradient was not apparent. A poor but detectable relationship emerged with an index of trampling. Canonical correlation analysis between the understorey vegetation ordination axes and 10 soil variables showed only the first canonical variate to be significant (r = 0.69, p = 0.0199). Major contributors to this were pH and the index of trampling intensity in the soils data. Because soil pH covaries with the survey design, variation in the understorey composition is attributed primarily to fragmentation and the sensitivity of woodland to urban pressure. Stand diversity versus quality as well as the sizes and shapes of urban woodlots are briefly considered.
Morphometric analysis of ultrastructural changes induced by Periconia circinata toxin in the outer root cap of sorghum
Authors: Arias Jonathan A. , Dunkle Larry D. , Bracker Charles E.
Published: April 2011

Outer root cap cells of sorghum seedlings treated with the host-specific toxin produced by Periconia circinata were analyzed morphometrically to detect changes in the quantities of cytomembranes and numbers of organelles and thus extend our observations of qualitative cytological responses to the toxin. In seedlings susceptible to the pathogen, brief (0.25 h) treatment with the toxin resulted in a marked and permanent decrease in the amounts of secretory vesicle membrane. By 2 h treatment, only secretory vesicle membrane was decreased, but longer treatments led to an increased amount of endoplasmic reticulum (4 h), which later decreased together with the amount of dictyosome membrane, while the amount of tonoplast increased (8 h). In resistant seedlings treated with the toxin, early but transient increases were detected in the quantities of plasma membrane, secretory vesicle membrane, dictyosome membrane, and endoplasmic reticulum and in the number of dictyosomes. Insensitivity to the toxin may involve the ability of resistant genotypes to recover from the toxic effects.
Influence of phenyl tryptophyl ether on adventitious root development in bean cuttings
Authors: Haissig Bruce E.
Published: April 2011

Rooting trials with bean (Phaseolus vulgaris cv. Top Crop L.) tested the effects of phenyl tryptophyl ether (PTRE) in comparison with tryptophol (TR, indole-3-ethanol), indole-3-acetic acid (IAA), and no treatment. PTRE was synthesized from tryptophol and phenol. Results indicated that IAA treatment enhanced primordium development significantly more than any other treatment that was tested. Effects of TR and PTRE treatment on primordium development were about equal. Results suggested that PTRE is not an auxin or is only a weak auxin in comparison with IAA.
Studies of the growth and mineral nutrition of barley varieties. II. Potassium uptake and its regulation
Authors: Siddiqi M. Yaeesh , Glass Anthony D. M.
Published: April 2011

Short-term K+ (86Rb) influx and its regulation by root K+ concentration was studied in barley varieties, using plants grown in complete nutrient solution at constant concentrations. The varieties employed in this study exhibited substantial differences not only in K+ influx but also in the intensity and the pattern of regulation of K+ influx. In the high-potential growth-rate varieties these K+ uptake characteristics were found to correlate well with their growth responses to K+ supply reported earlier by Siddiqi and Glass. Predictions of K+ influx, based upon kinetic constants and internal K+ concentrations derived from steady-state growth experiments, were found to correspond well with the observed fluxes for plants grown under these conditions over a wide range of root K+ concentrations. These predictions also provided good estimates of influx in CaSO4-grown plants for intermediate levels of root K+ concentration. However, at low root K+ concentration, predictions greatly overestimated observed fluxes, while at high root K+, influx was underestimated. Similarly, when kinetic constants derived from CaSO4-grown plants (whose root K+ concentrations were increased by rapid loading) were applied to steady-state plants, predicted influx values were close to observed in the intermediate range of root K+ concentration. However, at high root K+, influx was overestimated. These adjustments serve, in the steady state, to maintain tissue K+ concentration within rather narrow limits.
Vegetation studies at Polar Bear Pass, Bathurst Island, N.W.T. II. Vegetation–environment relationships
Authors: Sheard J. W. , Geale Dorothy W.
Published: April 2011

Vegetation–environment relationships are defined with the aid of principal-components analysis and canonical correlation analysis. In both the uplands and lowlands a moisture gradient, determined by measuring gravimetric moisture and indicated by organic carbon, is the most important environmental influence on the vegetation. In the uplands this gradient is also associated with snow depth (drifting) and in the lowlands with conductivity. The second environmental gradient in the uplands is associated with depth to permafrost and its soil textural correlates. Thus soil texture, independent of its effect on soil moisture status, influences the distribution of plant communities. In the lowlands the second environmental gradient is less clear but is also associated with depth to permafrost and, in addition, elevation and CaCO3 equivalent. Canonical correlation analysis shows that the components extracted by principal-components analysis of the vegetation data did not conform to the important trends of variation in the environmental data. Principal-components analysis is nevertheless an essential means of data reduction prior to the application of canonical correlation. The statistical model used in the study has potential advantages over the independent use of either principal-components analysis or canonical correlation.
Macrohyporia extensa and its synonym Poria cocos
Authors: Ginns J. , Lowe Josiah L.
Published: April 2011

Daedalea extensa Peck is an earlier name for Poria cocos Wolf, the fungus commonly called tuckahoe. Descriptions of the basidiomes and cultures are presented. In the northern deciduous forests of eastern North America the fungus typically occurs as a trunk and butt rot of mature, old-growth trees. The basidiomes appear after the tree has died. Reports of the fungus from Manitoba, Saskatchewan, and Alberta require confirmation because of confusion with the Canadian tuckahoe, Polyporus tuberaster Fr. Both D. extensa and Merulius sulphureus Burt are transferred to Macrohyporia.
Five species of Sarcinella from North America, with notes on Questieriella n. gen., Mitteriella, Endophragmiopsis, Schiffnerula, and Clypeolella
Authors: Hughes S. J.
Published: April 2011

Generic descriptions and illustrated accounts of type species are provided for four hyphomycetous genera with hyphopodiate hyphae: Sarcinella, Questieriella (n. gen.), Mitteriella, and Endophragmiopsis. Questieriella spp. produce curved to sigmoid 3-septate conidia, and are synanamorphs of Sarcinella and Mitteriella. Five North American species of Sarcinella and their Questieriella synanamorphs are illustrated and described: S. heterospora (teleomorph Schiffnerula pulchra; synanamorph Q. pulchra n. sp.) on Fraxinus; Sarcinella quadrata (syn. Epochnium quadratum) on Fraxinus; S. questieri on Cornus; S. copallina (syn. Stemphylium copallinum) on Rhus, and Sarcinella vernoniae (syn. Stigmella vernoniae) on Vernonia. Helminthosporium prestoniae and Mitteriella craterispermi are illustrated, described, and transferred to Questieriella. The type species of Schiffnerula, S. mirabilis, and of Clypeolella, C. inversa, and briefly described and ascoma initials and Questieriella anamorphs illustrated. Developmental similarities and differences between the teleomorphs of these two genera are considered analogous to those between the meliolaceous Asteridiella and Amazonia. A tabulation is presented of synanamorphs and teleomorphs of Sarcinella, Questieriella, and Mitteriella. Some correlations are suggested. Nearly all Sarcinella species have a Questieriella synanamorph, and the teleomorphs of species with this combination are in Schiffnerula. Other species of Schiffnerula produce Questieriella alone, or no anamorph. Most species of Clypeolella produce only a Questieriella anamorph, some produce none, and one species has a Mitteriella + Questieriella synanamorph combination. Three species described in Clypeolella are transferred into Schiffnerula, C. ricini Rac. (= S. ricini Hansf.), C. gymnosporiae, and C. salaciae. Available evidence suggests that Schiffnerula and Clypeolella are more closely related than is implied by their separation into two families.
Xylogénèse chez les Dicotylédones arborescentes. IV. Influence des bourgeons, de l'acide (β-indolyl acétique et de l'acide gibberellique sur la réactivation cambiale et la xylogénèse dans les jeunes tiges de Hêtre
Authors: Lachaud Suzanne
Published: April 2011

The application, in the middle of April, of a mixture of IAA (10−4 M) and GA3 (10−4 M), to apical stem of young beeches, disbudded more than 1 month ago, brings about the formation of an unusual early wood, composed of small xylary elements only, on a short distance. If the phytohormones are applied immediately on the following day after disbudding, the young trees produce normal early wood, on a long distance. GA3 applied alone has hardly any effect on cambial reactivation; IAA applied alone stimulates less cambial reactivation and xylogenesis than the mixture of IAA and GA3. The study of [3H]-IAA transport in apical shoots of the same trees shows that beeches disbudded 1 month ago have lost the ability to activate the auxin transport. Disbudding, carried out in the middle or at the end of the preactivation phase, affects the IAA transport system within a few days; a further exogenous phytohormone application cannot then replace buds and promote the renewal of cambial activity. In young beeches, the resumption of tissue ability to polarize the auxin transport, which in February characterizes the beginning of the preactivation phase, depends on buds; the maintenance and development of this ability are related to their presence.
Étude ultrastructurale de l'interrelation hôte–parasite entre le raisin et le champignon Botrytis cinerea : exemple de la pourriture noble en Sauternais
Authors: Pucheu-Planté B. , Mercier M.
Published: April 2011

The host–parasite relationship between Sauternes grapes and Botrytis cinerea was studied, on plants grown in the vineyards, with transmission and scanning electron microscopes. This study has revealed that the fungal attack is located on microfissures preexisting on the grapes. This attack does not appear before maturity, when the grapes' resistance to infection has decreased. The fungus grows then within the walls of skin cells while destroying pectic structures such as middle lamellae. After 4–8 days, hyphae emerge out of the fruit surface and further develop into conidiophores. During these host–parasite interactions, the biochemical activities of B. cinerea, such as metabolizations and syntheses, deeply modify the wall of superficial grape cells. Finally, grapes lose their water and concentrate various substances. Such a development leads to the particular aromatic features of Sauternes wines.
Efforts reproducteurs comparés d'un "poireau à graines" et d'un "poireau à caïeux"
Authors: Boscher J.
Published: April 2011

Reproductive effort in two cultivated leek species was determined under the same conditions. Reproductive effort was estimated as the percentage energy content in sexual organs and the organs of clonal growth out of the total energy content of vegetative and reproductive tissues at the end of the plant's life. One of the plants was essentially a sexually reproducing cultivar. The other, an Allium belonging to the porrum group, had not been selected for agronomic purposes. Though more diverse in its reproductive mode, this plant spreads essentially via underground vegetative means. Its development in the centre of France still reflects the morphological growth responses to the selective pressures of its original circummediterranean habitat. The portion of reproductive effort contributed by sexual organs in the two leek species was not significantly different, 31% in the cultivar and 35% in the nonselected plants. Total reproductive effort was much higher for the nonselected plants (55%) than that for the cultivar (33%), with the energy allocation to offset bulb production (20%) in the nonselected plants. The reproductive effort of the biennial cultivar approximates that found for numerous annual species. Despite the very high mortality of cultivar seedlings and cultivar inflorescences the small number of offset bulbs produced by the nonselected plant did not ensure as rapid a propagation as observed for the cultivar.
A quantitative histological and ultrastructural analysis of interactions between the flax rust and near-isogenic host lines varying in their degree of incompatibility
Authors: Coffey Michael D. , Allen Frances H. E.
Published: April 2011

Histological differences were evident in the leaves of eight near-isogenic lines of flax infected with the rust fungus Melampsora lini. Compared with the compatible L9 and M1 interactions, fungal growth was progressively more restricted in the moderately incompatible K and M4, incompatible M and P, and highly incompatible L and M3 interactions. This restriction took place in advance of appreciable necrosis of host cells in K, M4, M, and P. At 72 h the proportion of haustoria-containing cells which were necrotic was only 10–15% in K and M4. In M at 72 h necrosis was 80% or more at infection sites with small colonies but was negligible at sites with large colonies. In P, by contrast, a similar proportion of necrosis, 40% at 72 h, was present at all infection sites. However, in L and M3 host necrosis was much more rapid and the fungus was restricted to a few host cells. An early ultrastructural event was the appearance of extensive fibrillar deposits in the initially electron-lucent extrahaustorial matrices of both the incompatible M and P and moderately incompatible M4 and K interactions. A positive reaction with silver proteinate indicated that these matrical deposits contained carbohydrate, possibly a mucopolysaccharide or glycoprotein, but they were not extracted by either cellulase, pectinase, or chitinase. The extrahaustorial membrane, surrounding the haustoria in the compatible L9 and M1 interactions and the moderately incompatible K interaction was not stained by the periodic acid – phosphotungstic acid – chromic acid (PACP) procedure believed specific for the plasmalemma. In incompatible reactions clusters of electron-dense particles sometimes replaced starch in plastids of infected host cells. This event usually coincided with the appearance of extensive matrical deposits around fungal haustoria. At the same time particles were also found in plastids in uninfected host cells immediately adjacent to infection sites, particularly in the M and P interactions. These particles were extracted from thin sections by using pullulanase followed by α-amylase, indicating that they consisted of highly branched amylopectin.
Structure and biology of a new Harposporium attacking bdelloid rotifers
Authors: Barron G. L.
Published: April 2011

Harposporium botuliforme is described as a new hyphomycete endoparasitic on bdelloid rotifers in soil. The sausage-shaped conidia are ingested by the host, pass through the mastax, and germinate in the lower gut. Filiform germ tubes penetrate the gut wall and produce beaded assimilative hyphae in the body cavity which kill and colonize the host.
The cytogeography of Aster lanceolatus. III. Cytoecology in southern Ontario
Authors: Chmielewski J. G. , Semple J. C.
Published: April 2011

Aster lanceolatus Willd. is represented by five polyploid levels in southern Ontario: tetraploid (2n = 32), pentaploid (2n = 40), hexaploid(2n = 48), heptaploid (2n = 56), andoctoploid(2n = 64). Tetraploids were absent from the Niagara Peninsula in the southeast and Essex County, Kent County, Lambton County, and Elgin County in the southwest, whereas the hexaploids were ubiquitous. Correlations were found between chromosome number and habitat (community type), water content of the soil, physiographic region, and grouped physiographic region. These correlations notwithstanding, the distribution of the two predominant cytotypes in southern Ontario may also be related to historical factors.
A taxonomic study of Rhodosporidium capitatum
Authors: Nakagiri A. , Tubaki K.
Published: April 2011

Several strains of Rhodosporidium capitatum Fell, Hunter and Tallman, thought to be an obligate marine yeast, have been isolated from terrestrial leaf litter and from sand of a river, a brackish lake, and a seashore. Some unknown features of the life history have been elucidated in our study. Septal ultrastructure in R. capitatum was found to be similar to that of species of Tilletia, Filobasidium, and Filobasidiella; it is a primitive type of dolipore rather than the simple pore found in other species of Rhodosporidium. Septal ultrastructure appears to be correlated with promycelial type and physiological characteristics. Rhodosporidium is concluded to be a heterogenous taxon and taxonomic changes are needed.
Cytochemical specialization at the haustorial interface of a biotrophic fungal parasite, Albugo Candida
Authors: Coffey Michael D.
Published: April 2011

The haustorial apparatus of Albugo candida consisted of a narrow neck attached to a spherical body, which was packed with mitochondria. Covering the haustorial body was an electron-dense matrix which was bounded by the extrahaustorial membrane. This membrane, a continuation of the host cell plasmalemma, was highly convoluted with many short tentacles extending into the surrounding host cytoplasm. Single cisternae of host rough endoplasmic reticulum were always closely associated with the distal portion of the haustorial neck. Silver proteinate staining indicated that both the penetration jacket, a distinct zone surrounding the proximal part of the haustorial neck, and the extrahaustorial matrix were polysaccharide in nature, possibly complexed to other macromolecules such as proteins. The haustorial cell wall reacted only slightly with the silver proteinate, and in the distal region of the neck, there was no reaction. The fungal plasmalemma reacted strongly with the stain, except in the distal neck region, where there was no staining. With PACP, a staining procedure believed specific for the plasmalemma, the extrahaustorial membrane did not stain, whilst the host plasmalemma continuous with it did stain. The distal region of the haustorial neck wall also stained intensely with PACP clearly differentiating it cytochemically from the much lighter staining proximal neck and haustorial body walls. The penetration jacket stained more intensely than the extrahaustorial matrix with PACP, which might suggest a different chemical composition. Following incubation in 0.8 M sucrose osmoticum, the extrahaustorial membrane pulled away from the proximal neck wall, but remained tightly affixed to the distal neck wall, indicating that a tight junction existed between that membrane and the fungal cell wall in that region. Enzymic digestion with either cellulase or an endo-β-1,3-glucanase removed neither the haustorial body wall nor the extrahaustorial matrix. The significance of this finding is briefly discussed.
Urediniospore morphology of Puccinia species attacking Cardueae
Authors: Traquair J. A. , Kokko E. G.
Published: April 2011

Scanning electron microscopy of the urediniospores of three Puccinia species further resolved their spore ornamentation and supported observations made with the light microscope. In particular, the smooth hilum surface of P. jaceae Otth. urediniospores was clearly observed in contrast to the minutely verrucose and distinctly verrucose hilum of P. centaureae D. C. and P. carthami Cda., respectively. These observations in combination with other morphological features of urediniospores were useful in delimiting the three species and in recognizing two urediniospore forms characteristic of separate evolutionary lineages.
Inhibition of Endocronartium harknesii spore germination by metabolites of Scytalidium uredinicola and S. album, and the influence of growth medium on inhibitor production
Authors: Fairbairn N. , Pickard M. A. , Hiratsuka Y.
Published: April 2011

Endocronartium harknesii spores, stored desiccated at −20 °C for 6 weeks, germinated within 6 h at room temperature in phosphate buffer, pH 6. Type strains of Scytalidium album Beyer and Klingström and S. uredinicola Kuhlman et al. and two other isolates of S. uredinicola were compared for their ability to produce compounds which inhibit the germination of E. harknesii spores. Of five media tested, malt extract broth produced best results. Scytalidium album produced a fraction, molecular weight greater than 10 000, which caused spore lysis. Two strains of S. uredinicola formed chloroform extractable material, molecular weight less than 10 000, that inhibited germination of E. harknesii spores.
The effects of ozone and nitrogen fertilizer on tall fescue, ladino clover, and a fescue–clover mixture. II. Nitrogen content and nitrogen fixation
Authors: Montes Ruben A. , Blum Udo , Heagle Allen S. , Volk Richard J.
Published: April 2011

The effects of chronic doses of ozone (O3) and rates of nitrogen (N) fertilizer on N content of ladino clover (Trifolium repens L. cv. Tillman) and tall fescue (Festuca arundinacea Schreb. cv. Kentucky 31), and on N fixation by the clover were studied during the 1979 growing season. Plants of the two species were grown (i) in pots separately, (ii) together in open-top field chambers, and (iii) in ambient air plots. Mean 7 h/day (0930–1630 h eastern daylight time) O3 concentrations for the study period were 0.03 ppm in charcoal-filtered air chambers, 0.05 ppm in nonfiltered air chambers, 0.08 ppm in nonfiltered air chambers with O3 added for 7 h/day, and 0.05 ppm in ambient air. Shoot N concentrations (milligrams per gram dry weight) for clover and fescue were not modified by O3 exposures nor by N fertilization. Higher ozone levels led to reduced system N fixation (milligrams N per pot) by clover grown separately or together with fescue. Nitrogen fixation by ladino clover grown with tall fescue was 1.4 times greater than that by the clover grown alone. Nitrogen fixation by clover as estimated by the difference method was approximately 45% lower than N fixation as estimated by the 15N dilution method. Nitrogen fixation estimated by the difference method declined significantly with increasing N fertilization. This was not the case for N fixation estimated by the 15N dilution method.
Étude du développement hétéroblastique chez quelques espèces du genre Medicago
Authors: Damerval Catherine
Published: April 2011

Seven foliar types were defined for the first leaf in the heteroblastic development of seven annual species of Medicago L. Among the species, M. aculeata and M. murex have a typical foliar form. There is no relation between the first leaf and the succeeding trifoliolate one. The shape changes of the middle foliole of the trifoliolate leaves during the development allowed to establish a foliar sequence whose mean length was used to suggest an evolutive hierarchy among the taxa. Five quantitative variables were analysed on the first and on the sixth leaf for stability according to environmental conditions; the two stable variables (L/l and L/Pl) have a best discriminant value for the first leaf than for the sixth one. However, intraspecific heterogeneity is high in both cases. A relation between the flowering precocity and the mean value of one of the sixth leaf's variables (that is, the ratio of the length to the width of the foliole limb) was demonstrated in four species only. The heteroblastic development not only allows to establish a relation between foliar stage and physiologic age, but it itself constitutes a very good taxonomic and systematic criterium; it allowed to identify the seven species studied.
Spatial pattern and seed dispersal of Lithospermum caroliniense on Lake Huron sand dunes
Authors: Westelaken Irene L. , Maun M. A.
Published: April 2011

Studies on spatial pattern and seed dispersal of Lithospermum caroliniense (Walt.) MacMill. on Lake Huron sand dunes revealed that the ratio of pin to thrum plants was approximately 1: 1 on the south slope of the first dune ridge and slack. However, thrum plants had a higher proportion than pin plants on the crest of the dune ridge. The density of plants was highest on the south slope as compared with the other topographical zones. The spatial pattern of plants was nonrandom and plants were clustered in each of the three topographical zones. Most dispersed seeds of L. caroliniense remained within 1 m of the parent plant. The seed dispersal was not radially symmetrical around the parent plant. The steepness of the dune slope affected the dispersal distance of some propagules. Some seeds were retained on the parent, but few of these seeds were normal. About 40 to 64% of the recovered seeds contained holes in the seed coat. Eight months after marking, about one-third of the original marked seeds were still intact.
Abscisic acid resistant mutants in the fern Ceratopteris: characterization and genetic analysis
Authors: Hickok Leslie G.
Published: April 2011

Abscisic acid normally inhibits growth and male sexual differentiation (antheridia formation) in gametophytes of the fern Ceratopteris. Abscisic acid resistant mutants show increased growth and sexual differentiation in comparison with the wild type when cultured in the presence of abscisic acid. Two different mutants that confer resistance to the effects of abscisic acid have been fully characterized. One shows moderate resistance and the other strong resistance. The mutations involve separate but linked loci. Recombination between the loci yields double mutant (cis) recombinants that exhibit additive effects and show exceptional levels of abscisic acid resistance.
Role of dispersal date and changes in physiological responses in controlling timing of germination in achenes of Geum canadense
Authors: Baskin Jerry M. , Baskin Carol C.
Published: April 2011

This study examines the importance of the date of dispersal, and of the changes in the physiological responses of achenes before and after dispersal, in regulating timing of germination in Geum canadense Jacq. The effect of dispersal date on germination was tested by collecting achenes from the parent plants from September through June and sowing them on soil in an unheated greenhouse. Changes in germination responses were monitored by testing achenes of each collection in light and darkness over a range of thermoperiods. Regardless of test conditions, achenes required light for germination. At maturity in September, 90% of the achenes germinated at the September thermoperiod (30:15 °C (maximum:minimum)), but none germinated in November at the November thermoperiod (15:6 °C). Achenes sown in September germinated that autumn and the following spring, but none of those sown in November germinated until spring. As achenes overwintered on plants in the field, germination percentages decreased at 20:10, 25:15, and 30:15 °C and increased at 15:6 and 5 °C. Thus, achenes sown in early spring germinated immediately, while those sown in early summer did not germinate until later. Germination requirements of the achenes also changed after dispersal. Stratification lowered the temperature requirement for germination, and thus achenes sown in autumn germinated in March at temperatures that had inhibited germination in the autumn. Achenes dispersed in May and June did not regain the ability to germinate at high temperatures during summer, and they lost the ability to germinate at low temperatures. Therefore, most of these latter achenes did not germinate until the following spring, after they had been stratified during the winter.
A simple technique for making epidermal imprints using clear vinyl film
Authors: Redmann R. E.
Published: April 2011

Transparent, plasticized polyvinyl chloride film, pressed against a leaf surface and heated, produced an epidermal impression suitable for microscopic study. This rapid, simple method was tested successfully on 39 grass species, including those with corrugated surfaces and trichomes.
Some aspects of the vegetation ecology of the Nanoose–Bonell estuary, Vancouver Island, British Columbia
Authors: Dawe Neil K. , White Eric R.
Published: April 2011

A study of the vegetation of the Nanoose – Bonell salt marsh, Vancouver Island, British Columbia, was conducted during the period of May – September 1978. A total of 49 species of vascular plants was identified, 10 of which dominated the flora of the estuarine marsh. Six of those dominant species (Distichlis spicata, Glaux maritima, Salicornia virginica, Triglochin maritimum, Plantago maritima, and Atriplex patula) are tolerant of high salinities. Eight plant communities were identified and mapped within the study area. Aerial biomass was dominated by that of the Carex – channel edge community with a peak aboveground biomass of 1259 g dry weight/m2. Major factors affecting the occurrence and distribution of species within the marsh were salinity of the inundating water, elevation of the marsh platform, and soil texture.
Association of malva vein-clearing virus and rhabdoviruslike particles with mottle and vein clearing of malva plants
Authors: Henriques Maria-Ivone C. , Henriques Fernando S.
Published: April 2011

Thin sections of malva (Malva sp.) leaves collected in the field and showing mottle and vein-clearing symptoms were examined by electron microscopy. Cytoplasmic inclusions typical of potyvirus and consisting of pinwheels, laminated aggregates, and scrolls were readily observed. In addition, rhabdoviruslike particles were also seen in the perinuclear space of phloem parenchyma cells and within membranous sacs scattered throughout the cytoplasm of other vascular bundle cells. Occasionally rhabdoparticles could be found embedded in an amorphous electron-dense body located within the cell vacuole. The rhabdovirus particles, approximately 75 × 300 nm, were bound by a membrane with outer projections and had an inner core displaying cross striations. The cytoplasm of infected mesophyll cells had chloroplasts containing large amorphous inclusion bodies and had extensive membranous tubules that were frequently associated with the potyvirus inclusions. These ultrastructural aspects, the size of the particles, and the data on host range indicate that malva plants under study were doubly infected by viruses which were tentatively identified as malva vein-clearing virus and a previously undescribed rhabdovirus.
A new species of Glomus (Endogonaceae, Zygomycotina) mycorrhizal with barley in Alberta
Authors: Boyetchko S. M. , Tewari J. P.
Published: April 2011

A new species of endogonaceous fungus mycorrhizal with barley in Alberta is described. Glomus dimorphicum sp. nov. has two types of spores formed singly and in loose, often radiately arranged clusters. This new species produces very few vesicles, and arbuscule formation has so far not been observed.