bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in phosphorus and nitrogen availability on recessional moraines of the Athabasca Glacier, Alberta
Authors: Fitter A. H. , Parsons W. F. J.
Published: September 2008

Soil pH and concentrations of N and P in leaves of Dryas drummondii were measured on recessional moraines of the Athabasca Glacier, Alberta. Soil pH declined by 0.5 units per 100 years under Dryas but remained steady on bare ground. Water-soluble N and P levels in soil remained low at all stages, but N was higher under Dryas patches. Leaf P and N declined in the early stages of succession but increased later. This increase may represent the initiation of biotic N and P cycles in soil. These patterns contrast with those reported for other moraine successions.
Seasonal hypogeous sporocarp production in a western Oregon Douglas-fir stand
Authors: Hunt Gary A. , Trappe James M.
Published: September 2008

Hypogeous fungal sporocarps were collected over 32 months in a 35- to 50-year-old Douglas-fir stand in western Oregon. Production of the 9 ascomycete and 21 basidiomycete species collected during the study was dominated by a few species, Gautieria monticola, Hysterangium crassum, H. coriaceum, and Melanogaster sp.nov., each accounting for 5% or more of total annual dry weight. Estimates of annual productivity ranged from 2.0 to 3.2 or 22.0 to 35.4 kg dry weight/ha, depending on the method of calculation. Peaks in production were generally attributable to one or two species. Pronounced seasonal trends in production were not evident, although standing crops decreased in winter. The annual fruiting period of species varied from 3 to 11 months.
Shoot development in Betula papyrifera. VI. Development of the reproductive structures
Authors: Macdonald Alastair D. , Mothersill D. H.
Published: September 2008

Reproductive buds and developing inflorescences were collected weekly from mature trees during three successive growing seasons in northwestern Ontario. Material was prepared to show all stages of inflorescence and flower development and meiosis. Male inflorescence induction, involving the long-shoot bud apex and one or two proximal axillary apices, occurred in early May, before bud burst. Female induction involved the short-shoot bud apex and occurred in late June – early July. Both male and female partial inflorescences resembled a simple dichasium. The male flower consisted of usually two stamens and two or three tepals variably arranged. Meiosis occurred in late July – early August. Each female flower consisted of two stigmas, two connate tepals that were not noticeable at maturity, and a parietal placenta bearing two unitegmic ovules. Meiosis occurred in mid-June, after pollination in mid-May. It is concluded that developmental data do not help elucidate whether the inferior portion of the gynoecial wall is cauline or appendicular and whether the placenta is derived from axial or carpellary tissue. It is suggested that the trigger(s) evoking male and female inflorescence induction may be different and that the metabolic prerequisites for induction and early development would be supplied by winter-stored material for male development and by current metabolic processes for female development.
Detection of 10 additional pathogenesis-related (b) proteins in intercellular fluid extracts from stressed 'Xanthi-nc' tobacco leaf tissue
Authors: Hogue Richard , Asselin Alain
Published: September 2008

By using two-dimensional polyacrylamide gel electrophoresis, 10 additional pathogenesis-related proteins (b6c, b9c, b10a, b10b, b11a, b11b, b12, b13, b14, b15) were found in intercellular fluid extracts of stressed 'Xanthi-nc' tobacco leaf tissue. Proteins were identified as extracellular pathogenesis-related stress proteins by polyacrylamide gel electrophoresis analysis of three successive intercellular fluid extracts compared with homogenates before and after making intercellular fluid extracts. Four proteins (b12, b13, b14, b15) were only resolved by using native polyacrylamide gel electrophoresis for basic proteins in the first dimension gel and they were best extracted in 0.05 M Tris–HCl (pH 7.5) and 0.05 M CaCl2 as the infiltration buffer. The four basic proteins were found in intercellular fluid extracts from leaf tissue subjected to the same types of chemical inducers as previously described for tobacco pathogenesis-related proteins. Their accumulation was inhibited by basic amino acids or spermidine (1 mM) and they were resistant to endogenous and exogenous (trypsin, subtilisin) proteolysis. They did not bind to concanavalin A – Sepharose. These findings indicate that at least 23 proteins accumulate extracellularly after various types of stress in 'Xanthi-nc' tobacco green tissue. These proteins probably represent several groups or families of plant stress proteins.
Stigmina zilleri sp.nov., associated with brown leaf spot of broadleaf maple
Authors: Funk A.
Published: September 2008

Stigmina zilleri sp.nov. is described from a brown zonate leaf spot of broadleaf maple (Acer macrophyllum Pursh) in southwestern British Columbia, Canada.
Inhibition by carbon dioxide of the phototropic response of the Avena coleoptile to blue light
Authors: McIntyre Gordon I.
Published: September 2008

When intact oat coleoptiles (Avena sativa var. Harmon) were submerged in water, saturation of the water with CO2 promoted their elongation but eliminated their phototropic response to blue light. Increasing the pH of the CO2-saturated water prevented the promotion of coleoptile elongation but did not prevent the elimination of the phototropic response. In air, phototropic curvature was significantly reduced by 10% CO2 and was eliminated by 30%, without any reduction in growth. It is postulated that the increase in CO2 concentration may eliminate the phototropic curvature of the coleoptile by preventing the light-induced inhibition of growth on the illuminated side of the organ. Possible mechanisms are briefly discussed.
Somaclonal variation in the progeny of plants regenerated from callus cultures of seven inbred lines of maize
Authors: Zehr B. E. , Williams M. E. , Duncan D. R. , Widholm J. M.
Published: September 2008

Callus cultures were initiated from immature embryos of three dent corn inbred lines: FR27rhm (B73 derivative), 79-R4443, and EXL1; and four sweet corn (sh-2) inbred lines: f84-267, f84-275, f84-278, and f84-700. Extensive qualitative variation was noted in self-pollinated progeny of plants regenerated from callus of FR27rhm, EXL1, and f84-700; quantitative variation was measured in self-pollinated progeny of plants regenerated from cultures of almost all inbreds. Most qualitative mutations were visible in the first self-pollinated generation; chimerism in regenerated plants was indicated by initial segregation of some mutants after two self-pollinations. All culture-induced mutant phenotypes were similar to known spontaneous mutations in maize; preliminary data indicate most have single-gene recessive inheritance. For qualitative variation, average mutation frequencies per regenerated plant were calculated as 0.18, 0.71, and 0.64 for FR27rhm, EXL1, and f84-700, respectively. Differences in mutation frequency among the four sweet corn lines were determined to have a genetic basis. Significant quantitative variation included alterations in date of pollen shed and silk emergence, silk emergence relative to pollen shed, plant height, ear, and kernel characteristics. These results show genotypic differences in the extent of qualitative somaclonal variation, with some quantitative variation having possible applications for conventional corn breeding programs.
Variable loss of ectomycorrhizal ability in monokaryotic and dikaryotic cultures of Laccaria bicolor
Authors: Kropp Bradley R. , McAfee Brenda J. , Fortin J. André
Published: September 2008

The relative ability of sibling monokaryotic and reconstituted dikaryotic cultures of Laccaria bicolor (Maire) Orton to colonize short roots of Pinus banksiana Lamb. was studied using two different methods at 4, 8, and 12 months after isolation. Monokaryotic isolates varied in their ability to form ectomycorrhizae. Some lost the ability to colonize rootlets. Dikaryons formed soon after isolation from compatible mating type pairs were vigorous colonizers. A dikaryon formed after 12 months by pairing two competitive monokaryons formed abundant mycorrhizae. However, dikaryons formed after 12 months by using less competitive monokaryons showed a sharply reduced symbiotic ability. The isolation of one apparently nonmycorrhizal monokaryon is reported.
Release of an inhibitor of stipe elongation from illuminated caps of Coprinus congregatus mushrooms
Authors: Robert Jean-Claude , Bret Jean-Paul
Published: September 2008

Inhibition of stipe growth by a substance or substances produced in the cap of Coprinus congregatus fruit bodies cultivated in continuous light has been confirmed. Caps in which maturation was induced or prevented were transferred to decapitated stipes from normally growing sporophores. Stipes were most sensitive to inhibition when treated 16–18 h before maturity. Caps from continuous-light primordia only a few hours older than the photoinhibited stage were most inhibitory. When normal primordium maturation was induced by darkness followed by light, the inhibitor disappeared from the caps 18–20 h before maturity.
Increase in electrical resistance of plasmodesmata of Chara induced by an applied pressure gradient across nodes
Authors: Côté Richard , Thain John F. , Fensom David S.
Published: September 2008

By insertion of microelectrodes into the vacuoles of two adjacent internodal cells of Chara corallina, the changes of the potential differences across the plasma membranes and node were noted when a current of 0.40 μA was passed through the cells bathed in artificial pond water. When the solution bathing one cell was changed to artificial pond water + 102 mol m−3 mannitol, a significant increase was detected both in the membrane potential difference response and in the nodal potential difference response. This indicates that the lowering of turgor on one cell by 0.24 MPa increased the electrical resistance of the membrane of that cell and also the resistance of the plasmodesmata connecting the two internodal cells via the node. This is evidence in support of valving in plasmodesmata when a pressure difference is induced across their ends.
Nuclear behavior during teliospore germination and sporidial development in Tilletia caries, T. foetida, and T. controversa
Authors: Goates Blair J. , Hoffmann James A.
Published: September 2008

Germinating teliopspores of Tilletia caries, T. foetida, and T. controversa were stained with acetic orcein and examined with light microscopy. The general nuclear events were the same in the three species. Nuclei in teliospores stained only after a period of incubation. Teliospores contained a single interphase nucleus, which underwent meiosis and then zero to two synchronous mitotic divisions. At metaphase I – anaphase I, approximately four chromosomes were visible in each species. The nuclei migrated from the teliospore into the promycelium and then each migrated into a primary sporidium. At this stage there were usually fewer nuclei than primary sporidia. The nuclei divided almost synchronously in the primary sporidia, after which one of the daughter nuclei in each primary sporidium migrated to the tip of the promycelium and then into any remaining anucleate primary sporidia. Supernumerary nuclei remained in the promycelium or in the primary sporidia and eventually lysed. Mature primary sporidia usually contained one interphase nucleus. When T. caries and T. foetida were germinated at 5 as compared with 15 °C, the nuclei in most teliospores underwent one less synchronous division and the number of primary sporidia was reduced.
In situ and in vitro studies on the endophytic red algae Audouinella porphyrae and A. vaga (Acrochaetiales)
Authors: Tam Carol E. , Cole Kathleen M. , Garbary David J.
Published: September 2008

Audouinella porphyrae (Drew) Garbary and A. vaga (Drew) Garbary et al., endophytic species of Acrochaetiaceae growing in Porphyra and Pterosiphonia, respectively, were studied in the field and in culture. Host plants were common at Point No Point, Vancouver Island, from February to October, but endophytes were found only from May to October. Initial infections of both endophytes were in either the basal portions (species of Porphyra) or in the large principal axes (Pterosiphonia bipinnata) of the hosts. Although the endophytes had different morphologies when growing in situ, the species were morphologically similar when grown free of their host. Attempts to reinfect the original hosts and to cross infect the alternate hosts were unsuccessful, and the isolates of Audouinella produced epiphytic plants in mixed culture. In all culture situations plants reproduced asexually by means of recycling generations of monosporangial plants. The two species are considered conspecific, and A. vaga is reduced to synonymy under A. porphyrae.
Spore wall architecture of Glomus spp.
Authors: Bonfante-Fasolo Paola , Schubert A.
Published: September 2008

Vesicular–arbuscular mycorrhizal fungal spore walls are of important diagnostic value in identifying a species within a genus. Since ultrastructural descriptions have so far been limited to a few species, the aim of this work was to describe the ultrastructural organization of seven species of Glomus. All these species show a different overall architecture, confirming wall analysis as a good taxonomic criterion. Some features, however, were shared by all spores, chiefly a fibrillar texture given by highly ordered fibrils embedded in an amorphous matrix; the rhythm of the fibrillar deposition seems to be specific for each species. The meaning of such ordered deposition is discussed.
Dormance, germination et contenu protéique des semences de deux populations de Schoenus nigricans cueillies à des altitudes différentes
Authors: Bocchieri Emanuele , Floris Giovanni , Mulas Bonaria
Published: September 2008

The germination of seeds of two populations of Schoenus nigricans L. collected at two middle-west Sardinian sites at 5 and at 800 m above sea level were studied. Germination took place in the dark, in deionized water, at 10, 20, or 30 °C or at alternating temperatures (10:20 °C) with a 12-h thermoperiod. The tests of 60-day duration, demonstrated that 30 °C is an inhibiting temperature for the seeds here considered, while the alternating (10:20 °C) temperatures increase the germination compared with the constant (10 and 20 °C) conditions. This different behaviour was analysed with respect to the dormancy and germination of the seeds collected at the two stations. We suggest that, beyond the habitat factors, the morphological difference between the seeds are responsible for the results presently considered. The remarkable qualitative and quantitative differences concern mostly the protein content in the two seed populations. The environmental characteristics of the collecting sites of Schoenus nigricans L. are also discussed in detail.
Form variation in Mallomonas asmundiae and a description of Mallomonas sphagniphila sp.nov. (series Cornconticae, Mallomonadaceae)
Authors: Nicholls K. H.
Published: September 2008

Mallomonas asmundiae (Wujek & Van der Veer) Nicholls from Ontario possesses a considerable range in form of scales and bristles, the extremes of which have not been described previously. Detailed observations have demonstrated that considerable form variation may also be associated with individual cells. It was concluded that a single taxon is responsible for the range of form variation described. A new species, Mallomonas sphagniphila sp.nov. is described with some structural features similar to those of M. asmundiae and M. corcontica (Kalina) Péterfi & Momeu. An emended description of the series Corconticae Asmund & Kristiansen is provided to accomodate M. asmundiae, M. sphagniphila, and M. corcontica and their known ranges of form.
Somatic embryogenesis in Picea glauca (white spruce) and Picea mariana (black spruce)
Authors: Hakman Inger , Fowke Larry C.
Published: September 2008

Embryogenic callus was initiated from immature embryos of Picea glauca (white spruce) and Picea mariana (black spruce) cultured on defined media supplemented with 2,4-dichlorophenoxyacetic acid (1 × 10−5 M), N6-benzyladenine (5 × 10−6 M), and 1% sucrose. Seeds from cones stored at 4 °C for up to 3 months yielded embryogenic callus. Much higher frequencies of embryogenic callus were obtained from white spruce than from black spruce. Embryogenic callus contained loosely organized cells and somatic embryos of various sizes. The embryos consisted of a cluster of tiny dividing cells (embryonic region) with attached large vacuolated cells (suspensor region). Upon subculture of embrogenic callus to media either lacking growth regulators or with reduced concentrations (5 × 10−7 M, 2,4-dichlorophenoxyacetic acid and 5 × 10−6 M N6-benzyladenine) somatic embryos could be stimulated to develop into plantlets.
Self-incompatibility in diploid, tetraploid, and hexaploid Vaccinium corymbosum
Authors: Kloet S. P. Vander , Lyrene P. M.
Published: September 2008

The results of self-pollinations, sibling pollinations, and cross-pollinations were compared in terms of number of berries produced per 100 pollinated flowers, number of plump seeds per berry, percent seed germination, and time between pollination and fruit ripening. The population studied consisted of 344 Vaccinium corymbosum L. seedlings grown from seeds harvested from native populations at 26 sites extending from Florida to Nova Scotia. Diploid, tetraploid, and hexaploid plants were included in the study, but only homoploid crosses were made in order to avoid the confounding effect of the strong heteroploid crossing barriers in V. corymbosum. Self-pollinations resulted in great reductions in all fertility parameters. Sibling pollinations produced far fewer seedlings than cross-pollinations, mainly because the number of plump seeds per berry was reduced from an average of 21 for outcrosses to 13 for sibling crosses. Pollination with 1:1 mixtures of self and outcross pollen reduced plump seed number per berry to 5, compared with 14 for comparable outcrosses. The results were similar at all three ploidy levels. It is concluded that self-compatibility is low in natural populations of V. corymbosum.
Effects of nonyl phenol, a pesticide surfactant, on some metabolic processes of Chlamydomonas segnis
Authors: Weinberger Pearl , DeChacin Carmen , Czuba Margaret
Published: September 2008

Nonyl phenol (2.5 μg mL−1) was added to populations of synchronized cells of Chlamydomonas segnis Ettl. at four different phases of their life cycle, namely, at −4 and −2 h before the dark period (corresponding to the end of G1 and S phase), at the initiation of the dark period (the end of S phase and the beginning of G2), and 2 h into the dark cycle (at cytokinesis). The treatment was generally algistatic for all treatment periods. However, nucleic acid synthesis was substantially unaffected, leading to cells with a 1.6- to 2.0-fold augmentation of their DNA content. Algicidal effects were additionally obtained in cells treated in S phase. Perturbation of other metabolic processes including total protein and carbohydrate metabolism depended upon the timing of treatment relative to the phase of the life cycle.
Spectral properties of pseudobactin produced by Pseudomonas sp. B10
Authors: MacDonald James C. , Bock Cheryl A.
Published: September 2008

The siderophore, pseudobactin, was isolated from the plant growth promoting rhizobacterium Pseudomonas B10, and its absorption and corrected fluorescence spectra were determined over a range of pH values. These spectra were similar to those reported for other fluorescent siderophores from other Pseudomonas, so that differentiation of pseudobactin from such related siderophores by absorption or fluorescence spectra is not feasible.
Observations of fungal succession in the Mount St. Helens devastation zone, 1980–1983
Authors: Carpenter Steven E. , Trappe James M. , Ammirati Jr. Joseph
Published: September 2008

"Phoenicoid" fungi were observed fruiting on tephra deposits soon after the eruption of Mount St. Helens in May 1980. The first fungus observed was Anthracobia melaloma, which was common on tephra in both anamorph and teleomorph states. The rapid colonization of phoenicoid fungi on volcanic substrates is attributed to the changes in pH, chemical composition, and competitive interactions of microbes in the tephra. Generally, Ascomycetes were most abundant on the tephra in the first year after the eruption, followed by an increase of basidiomycete species. Sporocarps of phoenicoid fungi were an important substrate for colonization by photosynthetic nonvascular plants.
Some observations on the structure and function of the dinoflagellate pusule
Authors: Klut M. Emilia , Bisalputra T. , Antia N. J.
Published: September 2008

The pusules of an armoured dinoflagellate (Prorocentrum micans) and an unarmoured species (Amphidinium carterae) were examined for effects of certain physicochemical factors, physiological inhibitors, and cytological markers. Fluxes in both salinity and temperature caused pusular size changes, while colchicine, cytochalasin B, and pH changes (in the range 6.0–8.0) had little or no effect. The treatment with solutions of horseradish peroxidase, cationized ferritin, and lectins indicated uptake of these macromolecules via the flagellar canal into the pusules of both dinoflagellates. A three-dimensional model is proposed for the A. carterae pusule based on sequential sections examined by TEM. It is suggested that a fibrillar collar system, in conjunction with the flagellar beating, plays a crucial role in regulating the flow of materials in and out of the pusule. The overall results suggest a multiple function for the dinoflagellate pusule, including osmoregulation, macromolecule uptake, and probably, secretion.
Some exploratory experiments on the permeability of papillae induced in barley coleoptiles by Erysiphe graminis f.sp. hordei
Authors: Smart M. G. , Aist J. R. , Israel H. W.
Published: September 2008

Impermeability to ions and small molecules has been cited as a possible basis of the resistance of papillae to fungal penetration: nonporous papillae could prevent nutrient transfer or disrupt recognition between pathogen and suscept. We have tested the ability of lanthanum ions and a few, selected, small molecules to permeate both normal papillae and oversize papillae induced in barley coleoptiles by Erysiphe graminis f.sp. hordei. The probes were applied to living, usually untreated, coleoptiles and were detected by light or electron microscopy. Hydrophilic probes up to 389 Da were able to permeate both kinds of papillae freely. Although the results with the lipophilic probes were more difficult to interpret, the 479-Da probe did not freely permeate unaltered papillae of either kind. We conclude that unaltered papillae are permeable to some cations and small, hydrophilic molecules and infer that impermeability to similar chemicals cannot explain why oversize papillae, but not normal papillae, are highly resistant to penetration by the fungus.
The perennial Juncus of section Poiophylli in the Canadian prairie provinces
Authors: Catling P. M. , Spicer K. W.
Published: September 2008

Specimens of the perennial Juncus of section Poiophylli in major Canadian herbaria were examined to clarify the status of the group in the prairie provinces and to evaluate diagnostic characters. Six taxa are recognized. Of these, Juncus interior, which occurs in the prairie region of southern Manitoba, southern Saskatchewan, and southern Alberta, has been largely overlooked. Juncus confusus, frequently confused with Juncus tenuis, is confined to southwestern Saskatchewan and southern Alberta. Juncus dudleyi is widespread and common throughout the three provinces, whereas Juncus vaseyi is widespread but clearly less common in the prairie region than in the more northerly boreal forest areas. Juncus tenuis, also found mostly in the boreal forest region, is apparently frequent only in central Saskatchewan and is rare elsewhere. Juncus compressus is recently adventive in southern Manitoba. Reports of Juncus gerardii are discounted and J. oronensis is considered to be a rare hybrid. The diagnostic value of characteristics of the leaf auricle is affirmed through correlation with other distinctive characters such as the shape of the bracteole apex and bracteole length and to a lesser extent with anther length and seed length. Although seed lengths differ between J. dudleyi and J. interior, there is sufficient overlap in the prairie provinces to make this character unreliable for identification. Other taxonomic characters are discussed and an illustrated key and distribution maps are included.
La morphogenèse florale chez le pétunia. I. Analyse d'un mutant à corolle staminée
Authors: Vallade Jean , Maizonnier Daniel , Cornu André
Published: September 2008

The blind mutant of Petunia hybrida Hort. is characterized by a flower with a highly modified corolla: the much reduced or lacking corolla tube lamina is replaced by five supernumerary anthers, which produce scarce but fertile pollen. The ontogenic study of stamen and corolla formation shows the existence of three separate morphogenetic patterns corresponding to the development of undifferentiated appendages, the formation of pollen sacs or floral appendages, and the final intercalary growth (filament and corolla tube elongation), respectively. A first interpretative scheme of the floral morphogenesis is proposed and discussed.
Root dynamics of tallgrass prairie in wet and dry years
Authors: Hayes D. C. , Seastedt T. R.
Published: September 2008

Root dynamics were studied using root windows at Konza Prairie, a tallgrass prairie in north central Kansas, during dry (1984) and wet (1985) years. Amounts, production, and disappearance of root length decreased during drought but increased when rains resumed; however, standing crop remained low. The 1985 root lengths increased throughout the growing season, while production and disappearance remained constant. Yearly summaries of amounts, productivity, and decomposition by 10-cm increments in soil depth show that the effect of drought on these variables decreased with increasing soil depth. Turnover rates of root length averaged 564 in the dry year versus 389% in the wet year, with the largest difference noted in the 0- to 10-cm depth (800 in 1984 versus 540% in 1985). Production and decay patterns observed using root windows were also noted in root biomass data (obtained from soil cores). The average total root biomass turnover rate was 31%. Failure to sort below-ground materials into tissue types (rhizomes, roots) and live versus dead status results in reduced estimates of biomass turnover rates. The greatest possible separation of plant components presents the most comprehensive picture of (belowground) growth dynamics.
Effect of Congo red on hyphal morphogenesis and sporulation of Botryodiplodia theobromae
Authors: Suryanarayanan T. S. , Muruganandam V. , Sampath G.
Published: September 2008

The effect of Congo red, a dye which inhibits crystallization of cell wall polysaccharides, on hyphal differentiation and sporulation of Botryodiplodia theobromae Pat. was studied. The fungus has an obligate requirement for light to fruit in culture. The dye replaced the light requirement for formation of pycnidia. It also affected the structural integrity of the hyphal wall and the branching frequency of the hypha.
Gradient analysis of west central Vancouver Island forests
Authors: Gagnon Daniel , Bradfield Gary E.
Published: September 2008

The objective of this study is to describe the structure, composition, and ecological relationships of old-growth forests of west central Vancouver Island. Data were obtained by sampling 172 plots, at elevations up to 1000 m, located within 13 drainage areas. Relationships between vegetation and environmental variation were examined using indirect and direct gradient analysis. Successive reciprocal averaging ordinations using data from the tree, sapling, seedling, shrub, herb, and bryophyte – lichen strata led to the recognition of six vegetation groups (floodplain, subalpine, Pinus contorta, Pseudotsuga, Thuja, Abies) and 23 community types. Vegetation groups are differentiated along climatic and soil parent material gradients. The floodplain group occurs on alluvial terraces and the Pinus contorta group on rock outcrops. The vegetation of the Pseudotsuga group, dominant inland and influenced by fire disturbance, appears to respond to gradients of elevation and soil moisture. The Thuja group is found only near the coast, and its vegetation varies along gradients of soil nutrients and elevation, soil moisture having little effect. Wind is the strongest disturbance factor in this group. The vegetation patterns of the Abies group are correlated with elevation and soil moisture. Most community types of this group are associated with cool microclimates.
Historical vegetation change in the Kananaskis Valley, Canadian Rockies
Authors: Johnson E. A. , Fryer G. I.
Published: September 2008

This study compares the vegetation composition in the Kananaskis Valley from a forest survey in 1883 to another survey in 1972 and reconstructs the fire frequency for the period 1783 – 1882 and the period 1883 – 1972. A comparison of the 1883 to 1972 forest surveys using transition probabilities revealed that sites populated mostly by lodgepole pine (Pinus contorta) or Englemann spruce (Picea Englemannii) tended to remain the same in both surveys. The fire reconstructions for the period 1730 – 1972 showed no change in fire frequency after the beginning of European activity in 1883. Further, for the periods both before and after 1883, the valley burned, on average, once every 150 years. The distribution of the fire sizes for the 100-year period before 1883 was slightly larger than the period after 1883. It appears that in 1972 natural processes (site differences and fire occurrence) still dominated the changes in the vegetation composition and age.
Rhacomitrium pacificum, a new moss species from western North America
Authors: Ireland Robert R. , Spence John R.
Published: September 2008

Rhacomitrium pacificum, from western British Columbia, Washington, Oregon, and California, is described as new. The species is apparently related to R. heterostichum (Hedw.) Brid.
Manipulation of seed nitrate content modulates the dormancy-breaking effect of ethylene on Chenopodium album seed
Authors: Saini Hargurdeep S. , Spencer Mary S.
Published: September 2008

Germination of dormant Chenopodium album L. seed in response to ethephon and (or) KNO3, following experimental manipulation of the endogenous seed nitrate content, was studied to ascertain if the dormancy-breaking effect of ethylene was dependent on seed nitrate content. The seed originally contained a high (854 μg∙g dry weight−1) endogenous level of nitrate. Ethephon (100 mg∙L−1) induced over 70% germination in darkness at 22 °C, compared with 8% in the untreated controls. Application of KNO3 (1.01 g∙L−1), alone or together with ethephon, had a relatively minor effect. Elution of endogenous nitrate with distilled water for up to 72 h resulted in a marked decline in the response of seed to ethephon. Application of exogenous nitrate together with ethephon restored the lost sensitivity of seed towards ethephon. The results confirm that nitrate, specifically, modulates the dormancy-breaking action of ethylene on C. album seed.
Les mousses des îles St-Pierre-et-Miquelon
Authors: Etcheberry Roger , Abraham Daniel , Brassard Guy R. , Favreau Marc
Published: September 2008

One hundred and seventy-seven species of mosses are reported from the St. Pierre and Miquelon archipelago, off the south coast of Newfoundland. Of these, 54 species were not previously known from the archipelago. All earlier reports have been evaluated, and most have been confirmed or revised. The moss flora is predominantly composed of species that are widespread in Newfoundland. However, a number of mosses which occur in St. Pierre and Miquelon have a Newfoundland distribution restricted to the northwestern part of the island. Among the species that are widespread in St. Pierre and Miquelon is Antitrichia curtipendula, which was known in eastern North America only from a few localities. In southeastern Newfoundland, it is more frequent than was formerly thought; its distribution in the region is mapped.
Effet d'un traitement par l'acide abscisique sur la division cellulaire, les teneurs en ADN et l'élongation du bourgeon cotylédonaire de plants de pois décapités
Authors: Nougarède Arlette , Rondet Pierre , Landré Pierre , Rembur Jacques
Published: September 2008

When applied to pea (Pisum sativum L. var. nain hâtif d'Annonay) cotyledonary bud at the time of decapitation, cis-abscisic acid (ABA) induced a decrease in the mitotic indices of the meristem and subapical regions of the bud, in comparison with decapitated but not ABA treated control plants. ABA treatment delayed the entry of the G0–1 nuclei of the inhibited bud into the S phase and then into mitosis. Whatever the ABA concentration (10−3 to 10−7 M), the overall growth of the bud and the elongation of the cortical cells in its subapical region were not affected during the first 48 h. ABA induced an inhibition of bud elongation, all the more important since it was applied later after decapitation. When applied on a 48-h released bud, ABA induced an inhibition of elongation of the bud, a decrease in its mitotic activity, as well as a concentration of the shoot apex nuclei in the G1 phase of the cell cycle. However, this exogenous ABA treatment could not entirely replace the main axis in maintaining the inhibited state of the bud.
Two antagonistic fungi, "D 37" and Scytalidium album, reduce the formation of bore holes by Heterobasidion annosum in Norway spruce (Picea abies)
Authors: Lundborg Anna
Published: September 2008

The white-rot fungus Heterobasidion annosum was inoculated into stem discs of Norway spruce together with the antagonistic fungi "D 37" or Scytalidium album. When H. annosum grew alone in the wood, many bore holes were formed through the tracheid walls. The antagonists allowed growth of H. annosum in the wood to the same extent as in wood with H. annosum alone, but there were few bore holes when an antagonist was present. It is suggested that the antagonists decreased the ability of H. annosum to form bore holes.
Early grain development of the seg2 maternal-effect shrunken-endosperm mutant of barley
Authors: Felker Frederick C. , Peterson David M. , Nelson Oliver E.
Published: September 2008

Barley (Hordeum vulgare L.) plants that are homozygous for the seg2 mutation produce shrunken seeds with 15% of normal dry weight regardless of pollen source. Microscopical examination of developing grains sampled from 1 to 8 days after anthesis revealed abnormal endosperm development in seg2 compared with normal barley. Antipodal cells degenerated between 2 and 4 days after anthesis in normal grains, and the amount of endosperm cytoplasm increased and became cellular by 4 days after anthesis. Antipodals persisted beyond 4 days after anthesis in seg2, and the endosperm cytoplasm did not change in appearance or amount until 8 days after anthesis, when thin lobes of endosperm cells developed in the lateral regions. No central endosperm developed in seg2, but rather dorsal nucellar tissue was appressed directly against the ventral nucellar projection, eliminating the usual endosperm cavity. Maternal and embryo tissue of seg2 appeared to develop normally, although the rate of embryo growth was slower than in the normal cultivar. We suggest that seg2 barley would be useful as a genetic probe to study maternal control of endosperm development or antipodal function.
The effect of ozone on cottonwood – leaf rust interactions: independence of abiotic stress, genotype, and leaf ontogeny
Authors: Coleman James S. , Jones Clive G. , Smith William H.
Published: September 2008

The interaction of an acute ozone dose, plant genotype, and leaf ontogeny on the development of cottonwood leaf rust on eastern cottonwood (Populus deltoides Bartr.) was investigated. A rust-resistant (ST 66) and a rust-susceptible (ST 109) clone were exposed to charcoal-filtered air or were fumigated with 393 μg m−3 (0.20 ppm) ozone for 5 h. Forty hours after fumigation, leaf material of different developmental ages was inoculated with urediospores of Melampsora medusae Thum., and uredia production was measured after 10 days. Ozone fumigation of cottonwoods significantly reduced uredia production by M. medusae on both clones and all leaf ages without causing visible leaf injury or measurable changes in cottonwood height growth, leaf production, leaf length, or root/shoot biomass. Uredia production was strongly affected by ozone treatment, cottonwood genotype, and leaf age, but interactions among these three factors did not occur.
DNA content polymorphism and tissue culture regeneration in Caribbean pine
Authors: Berlyn Graeme P. , Anoruo Ambrose O. , Beck Richard C. , Cheng Jianping
Published: September 2008

The three varieties of Caribbean pine have significantly different amounts of nuclear DNA: Pinus caribaea var. caribaea, 11.5; P. caribaea var. hondurensis, 21; and, P. caribaea var. bahamensis, 25 pg. Dormant embryos of the three varieties had more nuclear DNA than germinating seedlings, and this extra DNA was spread through several classes from 2C to 7C; however, upon germination the seedling DNA rapidly reorganizes into the 2C–4C distribution typical of diploid plants. DNA content polymorphism of the dormant embryos among the three varieties was directly correlated with the diploid amount of DNA and with needle and cotyledon diversity. Buds regenerated from dormant embryo explants in tissue culture were genetically stable; however, the roots of regenerated plants had DNA contents ranging up to nine times the haploid amount. The instability is ascribed to the auxin content of the rooting medium, but buds regenerated or growing on this medium were stable. This bud stability and the production of buds on needle explants from 13-month-old regenerated seedlings are positive indicators for Caribbean pine biotechnology.
Pathological anatomy of black stain root disease of Douglas-fir
Authors: Hessburg Sr. Paul F. , Hansen E. M.
Published: September 2008

Twenty, black stain root disease infected Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) from the Oregon Cascade and Coast ranges were dissected; macroscopic and microscopic patterns of fungal colonization are described. Ceratocystis wageneri Goheen et Cobb colonized secondary xylem, disrupting xylem transport. Histopathological studies revealed that the tracheid-limited pattern of colonization exhibited by this fungus is unique among Ceratocystis wilt pathogens. Axial colonization by hyphae was confined to xylem tracheids and radial development of mycelia in ray tracheids was limited. Parenchyma and cambial necroses did not result from direct hyphal attack. Living host cells, although not invaded, were responsive to hyphal attack of adjacent functional xylem. Secondary phloem was never invaded by hyphae, but some dysfunction was evident. Host responses to infection were unsuccessful in curtailing the spread of the pathogen.
Resinomycena japonica and Resupinatus merulioides, new species of Agaricales from Japan
Authors: Redhead S. A. , Nagasawa E.
Published: September 2008

Two lignicolous species, Resinomycena japonica and Resupinatus merulioides, are described as new from Japan. Based on type studies, Panellus mirabilis Singer is transferred to Resinomycena and Xerotus anastomosus Lloyd is transferred to Marasmiellus.
Height and growth rings of Salix lanata ssp. richardsonii along the coastal temperature gradient of northern Alaska
Authors: Walker D. A.
Published: September 2008

Salix lanata ssp. richardsonii from open-tundra and streamside populations were studied at seven sites along a 100-km north–south transect following the Sagavanirktok River from the Alaskan arctic coast to the foothills of the Brooks Range. Mean July temperatures along this transect vary from 2.6 at the coast to 10 °C at the base of the foothills. Mean maximum heights of the sampled open-tundra willows increased from 10 ± 2 at the coast to 37 ± 8 cm at the southern end of the transect. Mean maximum heights of sampled streamside willows increased from 0 at the coast to 147 ± 25 cm. The mean maximum height of willows in both habitats showed very strong correlations with thawing degree-days. Mean growth-ring widths increased from 92 ± 20 at the coast to 188 ± 57 μm at the southern end of the transect and were also highly correlated with the temperature gradient. The results are discussed in light of other arctic studies of willow growth rings and Cantlon's system of vegetation subdivisions within the Alaskan arctic.
Quantitative variation of different monoterpenes around galleries of Ips typographus (Colleoptera: Scolytidae) attacking Norway spruce
Authors: Leufvén A. , Birgersson G.
Published: September 2008

Oxygenated and hydrocarbon monoterpenes present in gallery walls in the phloem at different phases of an attack by Ips typographus and associated microorganisms on Norway spruce trees were quantified. The concentration of monoterpene hydrocarbons rose rapidly at the onset of beetle attack and reached a maximum in the phloem surrounding nuptial chambers that were recently prepared by males. Thereafter, amounts decreased rapidly and then increased again in late attack phases. During the attack, the variation in the amounts of monoterpene hydrocarbons in the gallery walls was partly reflected by some oxygenated monoterpenes, such as myrtenol, present in the same tissue. Borneol, verbenone, terpinene-4-ol, and α-terpineol were present in low quantities in the early phases of attack, but large amounts of these compounds were found in gallery walls during later phases. The bark beetle semiochemicals, cis- and trans-verbenol, had their concentration maxima in gallery walls of finished nuptial chambers. Results of the present study suggest that some bark beetle semiochemicals are produced extraneously to the beetle by microorganisms such as yeasts. A simple model for the production of oxygenated monoterpenes in early and late Ips typographus attack phases is presented.
The cytogeography of Solidago uliginosa (Compositae: Astereae) in the Great Lakes region
Authors: Chmielewski J. G. , Ringius G. S. , Semple J. C.
Published: September 2008

Chromosome number determinations for 39 populations of Solidago uliginosa Nutt. from the Great Lakes region are reported for the first time. Tetraploids (2n = 36) were restricted to limestone outcrops, whereas diploids (2n = 18) were widely distributed but not found on these outcrops.
Protein mobilization from cotyledons of de-shooted pea seedlings
Authors: Malek Ladislav
Published: September 2008

The role and regulation of proteolytic enzymes in protein mobilization from seed storage tissues is not fully understood. Surgical removal of the shoots of 5-day-old pea seedlings was found to double the longevity of the cotyledons remaining attached to the roots. Despite the healthy appearance of these cotyledons (green, turgid), their protein content decreased rapidly. After 14 days of seedling growth, the protein level decreased, but remained about 3 to 4 times greater than the amount present in normally senescing cotyledons of untreated seedlings. Specific differences in the cotyledonary albumin and globulin complement of 14-day-old de-shooted and control seedlings were revealed by electrophoresis. Proteolytic (casein degrading) activity was present in dry and senescing cotyledons. The need to purify this enzyme prior to a further characterization of its role in the senescence of cotyledons was demonstrated.
Significant levels of self-fertilization in natural populations of tamarack
Authors: Knowles Peggy , Furnier Glenn R. , Aleksiuk Mary A. , Perry Daniel J.
Published: September 2008

The mating system in five northern Ontario populations of tamarack (Larix laricina (Du Roi) K. Koch) was investigated using five allozyme marker loci (Aat3, G6p, Mdh3, Pgi2, and 6pg2). The mean multilocus outcrossing rate was 0.729, lower than estimates reported for most other conifers. The one population with a much higher stand density than the others had the highest outcrossing rate (0.908). Significant heterozygote deficiencies, relative to Hardy – Weinberg expectations, were observed at most loci in all five embryo populations. In contrast, there appeared to be few cases of heterozygote deficiencies in the adult populations, indicating that many inbred seedlings do not survive to the adult stage.
Dispersal of eastern red cedar (Juniperus virginiana) into pastures: an overview
Authors: Holthuijzen Anthonie M. A. , Sharik Terry L. , Fraser James D.
Published: September 2008

Seed dispersal, predispersal and postdispersal seed predation, seed dormancy, and germination were followed for four cone-bearing eastern red cedar trees (Juniperus virginiana L.), a predominantly avian-dispersed plant species, in pastures in southwest Virginia from June 1981 through May 1982. Within 12 m from the source trees, 34.7% of the total cone crop was recovered. Recovered material consisted of unripe cones, ripe cones, parasitized cones, and pulpless seeds evacuated by birds, averaging 17.9, 11.6, 1.0, and 4.2%, respectively, of the cone crop. Predispersal avian predation of seeds accounted for 3.1% of the cone crop. After 1 year 0.9% of the cones remained on the trees. The remaining 61.3% of the cone crop was dispersed at least 12 m from the source trees. Less than 3% of the cone crop is likely to germinate within 12 m of the source trees, while about 25% is likely to germinate at greater distances. Red cedar seeds passed unharmed through the digestive tract of avian dispersers and showed greater total germination than manually depulped seeds. Red cedar seed banks were not found under a chronosequence of red cedar stands; seeds generally lost their viability within one growing season. Seed shadows decreased exponentially with distance from cone-bearing trees. A similar distribution function was reflected in the spatial distribution of red cedar cohorts colonizing pastures near source trees. The large cone crop, diverse avian disperser assemblage, physiological adaptation of red cedar to open, xeric sites, and availability of seed sources in fence rows contribute to the successful invasion of pastures by this species.
Effect of acidic precipitation on bean plants
Authors: Trites Lary F. , Bidwell R. G. S.
Published: September 2008

Direct and indirect effects of acidic precipitation on the rates of CO2 exchange of bean plants (Phaseolus vulgaris L., cv. Tendergreen) were measured. Solutions of HCl, HNO3, H2SO4, and artificial acid rain at pH values from 2.7 to 5.0 sprayed on leaves at intervals (varying from 1 to 5 days in different experiments) for 3 weeks had no effect on rates of CO2 exchange. Some lesions appeared on leaves where chlorophyll was destroyed; apparently undamaged areas of the leaf compensated by increasing the rate of photosynthesis. Application of acidic solutions to pot soil in which the plants were growing or growing plants in nutrient solutions at pH 3.0 caused serious effects in the leaves, resembling Ca or Mg deficiency symptoms, but no obvious deleterious effects to the roots. Effects of acid were greater when Ca, Mg, P, or N were supplied at reduced concentration. Reducing the concentration of K, Fe, or the mixture of trace elements normally supplied did not influence the effect of acidity of the nutrient solution. The uptake and distribution of Ca, Mg, P, and N throughout the plant was not affected by the acid treatments. It is concluded that acidic soil water or nutrient solutions interfere with the metabolism of calcium, magnesium, phosphorus, and nitrogen in the leaves.