bluuebunny/crossref_metadata_2025 huggingface dataset:
The floral abscission zone in series Acaulia and related taxa of Solanum section Petota
Authors: Kardolus J P , Bezem N
Published: April 2011

Species of the genus Solanum usually possess pedicels with a floral abscission zone, which is designated the "articulation" or "joint." A distinct group of tuber-bearing wild potatoes, series Acaulia, is characterized by an indistinct or completely absent articulation. The anatomy of pedicels without articulation is compared with that of articulated pedicels. No abscission zone is observed in pedicels without an articulation, a situation found in the tetraploids Solanum acaule Bitter ssp. acaule and S. acaule ssp. punae (Juz.) Hawkes & Hjert. The hexaploids Solanum albicans (Ochoa) Ochoa and S. acaule ssp. palmirense Kardolus of series Acaulia have an anatomically incompletely differentiated abscission zone. Solanum acaule ssp. aemulans (Bitter & Wittm.) Hawkes & Hjert. (2n = 48) has articulated pedicels and a floral abscission zone. The absence of a floral abscission zone is presumably a recessive trait. The special features of pedicel articulation in series Acaulia are discussed in relation to the "jointless" mutations in tomato. The position of the articulation on the pedicel is concluded to be less significant for taxonomy than generally considered.Key words: Solanaceae, Solanum acaule, anatomy, "jointless" mutation, pedicel articulation, taxonomy.
Capnodiaceous sooty mold phylogeny
Authors: Reynolds Don R
Published: April 2011

Sequences from the 18s rDNA gene of representatives of the capnodiaceous sooty mold families Antennulariellaceae, Capnodiaceae, and Metacapnodiaceae as well as 14 ascomycete taxa representing the Plectomycetes, Dothideales, Pyrenomycetes, and Pleosporales, and yeast outgroups were analyzed. Sooty mold capnodiaceous ascomycetes comprising were found to be a monophyletic group, the Capnodiales. The convergent origin of the bitunicate ascus associated with the periphysoid sterile element is validated. The major Capnodiales characters are the foliicolous habit, darkly pigmented hyphae, and a distinctive periphysoid sterile element associated with a fissitunicate type of bitunicate ascus.Key words: ascomycetes, Capnodiales, periphysoid sterile elements.
Water relations, chlorophyll fluorescence, and membrane permeability during desiccation in bryophytes from xeric, mesic, and hydric environments
Authors: Deltoro Vicente I , Calatayud Angeles , Gimeno Cristina , Barreno Eva
Published: April 2011

The interactions among water content, chlorophyll a fluorescence emission, and potassium leakage were analyzed during dehydration in desiccation-tolerant bryophytes from xeric habitats (Hedwigia ciliata (Hedw.) P. Beauv., Hypnum cupressiforme Hedw., Leucodon sciuroides (Hedw.) Schwaegr., Orthotrichum cupulatum Brid., Pleurochaete squarrosa (Brid.) Lindb., Porella platyphylla (L.) Pfeiff., and Tortula ruralis (Hedw.) Gaertn., Meyer & Scherb.) and desiccation-intolerant bryophytes from mesic and hydric environments (Barbula ehrenbergii (Lor.) Fleisch., Cinclidotus aquaticus (Hedw.) B. & S., Conocephalum conicum (L.) Underw., Lunularia cruciata (L.) Dum. ex Lindb., Palustriella commutata (Hedw.) Ochyra, Philonotis calcarea (B. & S.) Schimp., and Rhynchostegium riparioides (Hedw.) Card.). Their fluorescence characteristics at low water content were low efficiency of photosynthetic quantum conversion, closed photosystem II reaction centers, and strong nonphotochemical quenching only in desiccation-tolerant species. Full restoration of fluorescence parameters upon rewatering in species from xeric environments indicated that the photosynthetic apparatus was fully functional after desiccation. Species from hydric and mesic habitats were unable to restore photochemical activity. This might be a consequence of photoinhibition but also of membrane damage, as indicated by the large leakage of potassium. It is suggested that the capacity to enhance thermal energy dissipation during dehydration might have evolved in species from xeric environments as an adaptation to the utilization of an erratic supply of water. This protective strategy would lower the probability of photodamage during water loss and thus maintain the photosynthetic apparatus in a quickly recuperable state.Key words: bryophytes, chlorophyll fluorescence, dehydration, desiccation tolerance, thermal energy dissipation.
The effects of rock climbing on the vegetation of three Minnesota cliff systems
Authors: Farris Michael A
Published: April 2011

I quantified the distribution and abundance of major plant taxa on three distinct cliff systems in Minnesota and examined the effects of recreational rock climbing on that vegetation. The three cliff systems differed significantly in the amount and type of vegetation present in undisturbed plots. Frequencies of most taxa were lower in climbed areas, although the differences were generally not significant. Total plant cover was significantly lower in climbed plots at all three locations. Fragile forms, such as umbilicate and fruticose lichens, were especially sensitive to human disturbance. The microtopography of the rock substrate had a significant impact on both the amount of vegetation present and the use of a cliff area by climbers. Cracks in the rock were significantly more common in climbed areas while ledges were less common. Microtopography also varied with the technical difficulty of the climbing route. While human impact decreased vegetation frequency and cover on these cliffs, identification of causal links between human disturbance and vegetation structure must include a careful assessment of the geological and environmental factors that strongly influence both human use and vegetation dynamics.Key words: cliff, lichen, rock climbing, vegetation, Minnesota, human disturbance.
RAPD analysis of the relationship of North and South American subspecies of Fragaria chiloensis
Authors: Porebski Sue , Catling Paul M
Published: April 2011

To improve the intraspecific classification of Fragaria chiloensis (L.) Duchesne, 35 plants including 5 North American ssp. lucida, 15 North American ssp. pacifica, and 15 South American ssp. chiloensis were analysed using random amplified polymorphic DNA (RAPDs). From 100 primers screened, 12 were selected providing 62 scorable polymorphic bands. The phenogram (cophenetic correlation, r = 0.99) based on UPGMA clustering of Jaccard's coefficients revealed a clear division between North American and South American plants, but only partial separation was shown between the two North American subspecies. This is the first comprehensive molecular evidence for major genetic divergence between the North American and South American subspecies of F. chiloensis and suggests greater genetic variation within the Canadian material of the North American ssp. pacifica than within the South American ssp.chiloensis. These findings strongly support protection and utilization of wild Canadian Fragaria germplasm for crop improvement.Key words: strawberry, Fragaria chiloensis, ssp. chiloensis, ssp. pacifica, ssp. lucida, RAPD, variation, germplasm, Canada, United States, Chile.
Molecular and morphological discrimination betweenTylospora fibrillosaandTylospora asterophoramycorrhizae
Authors: Eberhardt Ursula , Walter Lutz , Kottke Ingrid
Published: April 2011

Among the mycorrhizal types of spruce, Tylospora-type mycorrhizae are the most constant and abundant. Two species of the genus Tylospora occur in Europe, Tylospora fibrillosa and Tylospora asterophora. Mycorrhizae of T. asterophora are described in detail for the first time. Sequences of the internal transcribed spacer (ITS) of the ribosomal genes were obtained from T. fibrillosa and T. asterophora mycorrhizae, sporocarps, and cultured mycelium. Discrimination and identification of the two species by ITS polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) are discussed in the light of inter- and intra-specific variability. Species-specific PCR primers were designed to distinguish both species. Molecular screening of Tylospora-type mycorrhizae from field material led to unambiguous results, whereas morphological identification is likely to fail because of great similarity even at the microscopic level.Key words: Tylospora asterophora, Tylospora fibrillosa, ectomycorrhizae, taxon specific primers (TSOPs), ITS sequences.
Needle flavonoid variation in coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) populations
Authors: Kaundun Shiv Shankhar , Lebreton Philippe , Bailly Alain
Published: April 2011

The variability of six Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) populations was studied with the help of needle flavonoids. Of the two proanthocyanidins and six flavonols detected and measured by high performance liquid chromatography, myricetin and prodelphinidin allowed partial separation of the sampled coastal Douglas-fir populations into three geographical groups. Even though conspicuous differences were found between the northernmost and southernmost provenances, flavonoid markers were insufficient to identify the origin of a coastal Douglas-fir population without ambiguity. In accordance with other genetic markers, it would be inappropriate to recognize races within the sampled area of coastal Douglas-fir. From a biogenetical point of view, the synthesis of prodelphinidin appears to be governed by a gene present in two codominant allelic forms. The alleles are differently expressed from one population to another in such a way that there is a latitudinal cline of prodelphinidin throughout the sampled coastal Douglas-fir populations. The gradual decrease of prodelphinidin from south to north tends to support the idea that coastal Douglas-fir has migrated in this same direction from ice-free refugia of the Wisconsin glaciation period. To confirm the latitudinal cline and the mode of inheritance of prodelphinidin in coastal Douglas-fir, additional populations should be analyzed and segregation data from known pedigrees should be obtained respectively.Key words: Pseudotsuga menziesii var. menziesii, Pinaceae, flavonoids, geographical variation.
Gametophyte morphology and reproductive biology in Elaphoglossum
Authors: Chiou Wen-Liang , Farrar Donald R , Ranker Tom A
Published: April 2011

Gametophyte morphology, behavior, and growth habit of Elaphoglossum alatum Gaud., Elaphoglossum callifolium (Bl.) Moore, Elaphoglossum crassifolium (Gaud.) Anderson & Crosby, Elaphoglossum marginatum (Wall ex Fee) Moore, and Elaphoglossum yoshinage (Yatabe) Makino were observed on artificial agar medium. The morphology of these gametophytes are very different from those of Bolbitis, a genus of Lomariopsidaecae thought to have a close relationship with Elaphoglossum. The growth habit of Elaphoglossum gametophytes, like many other epiphytic species, is perennial and clone forming. Isozyme analysis of naturally occurring sporophytes of E. alatum, E. crassifolium, and Elaphoglossum paleaceum (Hook. & Grev.) Sledge suggest that sporophytes of E. alatum and E. crassifolium are diploid and derived from highly outbreeding populations. Fixed heterozygosity in E. paleaceum suggests that sporophytes of this species are polyploid, but at least some outcrossing occurs. High genetic loads determined from single gametophyte cultures of E. callifolium and E. crassifolium indicate low probabilities of successful intragametophytic selfing. Several tests indicate, however, that these species neither produce nor respond to antheridiogens. Therefore, intergametophytic mating in these species is likely maintained by genetic load. This mating behavior is promoted by a perennial and clone-forming growth habit which may function to prolong the life-span and to enlarge the space occupied by individual gametophytes.Key words: Elaphoglossum, fern gametophyte, reproductive biology, breeding system.
Freshwater ascomycetes: two new species of Ascotaiwania from North America
Authors: Fallah Payam M , Crane J Leland , Shearer Carol A
Published: April 2011

Two new species of Ascotaiwania, A. persoonii and A. hughesii, collected from submerged decorticated wood in lotic and lentic habitats, are described and illustrated. The anamorph for A. hughesii, Helicoon farinosum, is confirmed by cultural studies. Ascotaiwania hsilio is reported for the first time from North America.Key words: Amphisphaeriaceae, aquatic, lignicolous, taxonomy.
Evidence for high rates of self-fertilization in the alpine herb Epilobium anagallidifolium (Onagraceae)
Authors: Kelley Scott T , Latta R G
Published: April 2011

Epilobium anagallidifolium Lam., alpine willow-herb, is a small perennial herb found growing along the moist creek sides of recent snow runoff in alpine regions. The floral morphology of E. anagallidifolium, in which the anthers rest neatly atop the stigma when the flower is closed, indicates this species may regularly self-fertilize. We determined the mating system of this species by analyzing allozyme loci from 240 individuals in 20 different families (12 individuals per family) for two polymorphic enzymes: PGI and MDH. In every family studied, all of the individuals within a family were homozygous for the same alleles. These data support the hypothesis that Epilobium anagallidifolium reproduces primarily through self-fertilization, although we cannot rule out the possibility of occasional pollinator-mediated cross pollination.Key words: Epilobium anagallidifolium, mating system, pollinator scarcity, inbreeding, allozymes.
A so called "rudimentary gall" induced by the gall midge Physemocecis hartigi on leaves of Tilia intermedia
Authors: Rohfritsch Odette
Published: April 2011

The gall midge Physemocecis hartigi Liebel (Cecidomyiidae) induces a pustule gall on the leaves of the linden (Tilia intermedia D.C.). During larval development, the gall is inconspicuous on the host. Once the larva has left the gall (2 weeks after the eggs have been laid) the tissue desiccates and turns brown. We have found that the gall is initiated by the first instar larva, which attacks epidermal cells with sharp mandibles and kills a few precisely localized cells. Cells elongate perpendicularly to the attacked leaf lamina and eventually completely cover the larva. We did not observe cell division. The second instar larva enlarges the small gall cavity by inducing cell wall maceration between the vascular bundle sheath cells and the phloem. The larva feeds on cells that protrude from the open vascular bundles and on the palisade parenchyma. Contrary to earlier observations, we found these cells to be structurally modified into a nutritive tissue. The nutritive cells are hypertrophied and turgid, and have a centrally located enlarged nucleus and small vacuoles; the hydrated cytoplasm contains numerous concentric layers of endoplasmic reticulum, as well as many dictyosomes and autophagic structures. The presence of large pit fields in the cell wall suggests intense symplastic transport of solutes. The larva feeds by puncturing the turgid cells. These punctures may reach deeply into the cells but the cell wall is never ruptured; instead, the wall grows around the mandibles. Starch accumulates around the feeding area. Farther away, the modified leaf tissues contain phenolic substances. The pustule gall of P. hartigi is a highly specialized structure, supporting rapid larval development. The lack of conspicuity and the large larval cavity allow the larva to escape most of the parasitoids. Larval development goes almost without important host defense reactions and, therefore, is of low energy costs for the host. The wounding pattern of the first instar larva is highly species specific and shows a large degree of host adaptation.Key words: gall midge, gall, nutritive tissue, Physemocecis hartigi, Tilia intermedia.
Effect of flowering phenology and habitat on pollen limitation in Erica multiflora
Authors: Santandreu Marc , Lloret Francisco
Published: April 2011

Pollination can be a major factor influencing reproductive success in plants. Pollination may be influenced by variability in pollen production and vector activity associated with environmental heterogeneity in time and space. These factors were addressed experimentally using hand pollinations of Erica multiflora L., a shrub occurring in the western Mediterranean Basin that exhibits a long flowering period. Variation in pollen limitation was considered three times (early, peak, and late) over the flowering season and between two habitats (shrubland and pine forest). The breeding system and the pollination vectors were also studied by hand pollination and exclusion experiments. Xenogamy and natural pollination (control) treatments produced more seed and fruit set than geitonogamy and autogamy treatments. Insect visitors were less abundant at the end of the flowering period and in the pine forest habitat. Pollen limitation was not different between habitats, but it changed over the flowering period. Fruit set was pollen limited at the early flowering time, when less flowers were available. Both seed and fruit set were pollen limited at the late flowering time, when both flower density and insect visitors were lower. Seed and fruit set were not pollen limited at the peak of the flowering period, but their low values suggest resource limitation associated with a large number of developing fruits.Key words: breeding system, fruit set, hand pollination, insect pollinator, phenology, seed production.
Natural revegetation of two block-cut mined peatlands in eastern Canada
Authors: Robert Élisabeth Claire , Rochefort Line , Garneau Michelle
Published: April 2011

Limited areas of post-mined peatlands are recolonized by Sphagnum-dominated communities. This study aims to recognize the spontaneous Sphagnum re-establishment process and to verify if Sphagnum directly colonizes the residual peat. Conditions favoring Sphagnum revegetation are suggested. Analyses of vegetation macrofossils of the newly formed peat allow the identification of colonizing species and vegetation succession profile. Botanical components of the pioneer horizon suggest that Sphagnum species can directly colonize the residual peat. When Polytrichum strictum (Kaulf.) Presl and Eriophorum spissum Fernald are present as early colonists, they are rapidly overgrown by Sphagnum species in the succession profile. Vegetation succession resulted mainly in the formation of hummocks and lawns dominated by Sphagnum fuscum (Schimp.) Klinggr., Sphagnum capillifolium (Ehrh.) Hedw., and Sphagnum magellanicum Brid., with a more or less dense ericaceous shrub cover. Floristic, hydrological, and chemical features indicate that a fibric peat accumulation ecosystem is progressively or partially restored.Key words: cut-over peatlands, restoration, Sphagnum, vegetation macrofossil, acrotelm.
Ovule, embryo sac, embryo, and endosperm development in leafy spurge (Euphorbia esula)
Authors: Carmichael Jeffrey S , Selbo Sarena M
Published: April 2011

Leafy spurge (Euphorbia esula L.) is a noxious, invasive weed that dominates many agriculturally important regions. While many research efforts are currently aimed at controlling the spread of this plant, relatively little is known about its sexual reproductive biology, especially from a structural perspective. This report describes key features of ovule development, embryogenesis, and endosperm formation in leafy spurge. Ovules are anatropous, bitegmic, and form a zigzag micropyle. A distinct elaisome (caruncle) and hypostase are formed as ovules mature. Obturators are present and are derived from placental tissue. The embryo sac conforms to the Polygonum type. A single embryo is formed in each seed and stores nutrients primarily as globoid protein bodies. Endosperm is persistent and also contains protein bodies as its primary nutrient reserve. Preliminary structural evidence is presented that indicates the potential for apomixis.Key words: leafy spurge, Euphorbiaceae, Euphorbia, ovule, endosperm, embryo.
The floral development and anatomy ofCarica papaya(Caricaceae)
Authors: Decraene LP Ronse , Smets E F
Published: April 2011

Floral development and anatomy of Carica papaya L. have been investigated to shed light on (i) the morphology of the flower, (ii) the structural basis for the pollination mechanism, and (iii) the relationships of the Caricaceae. Carica is mostly dioecious with a strong dimorphism between staminate and pistillate flowers. The development of staminate flowers resembles that of pistillate flowers up to the initiation of the stamens. Further development leads to highly diverging morphologies. In staminate flowers a combination of contorted growth and the development of a common stamen-petal tube produces a long floral tube. The gynoecium grows into a central spearlike pistillode. The pistillate flowers have no traces of stamens and initiate five antesepalous carpel primordia. Common basal growth leads to the development of a large ovary with staglike stigmatic lobes and intruding placentae covered with numerous ascending ovules. Floral anatomy of staminate and pistillate flowers is described. The nature of the colleters is discussed. The morphological basis for reward production in C. papaya is clarified, and conflicting views on pollination are discussed. Nectaries of staminate flowers are located on the central rudimentary pistil and not at the base of the stamens, as previously reported. The anthers contain packages of calcium oxalate crystals. Pistillate flowers produce no nectar but have a stigmatic exudate. We compared the floral development and anatomy of Carica with that of Adenia (Passifloraceae) and Moringa (Moringaceae) in the view of a relationship with other glucosinolate-producing families. Although a derivation of the unisexual flowers from bisexual ancestors is probable, Storey's hypothetical derivation of pistillate flowers is not supported by the floral ontogeny and vasculature.Key words: Adenia, Caricaceae, Moringa anatomy, calcium oxalate packages, dioecy, floral structure, nectaries, ontogeny, pollination, systematic relationships.
Cytogenetic variation in populations of Armeria maritima (Mill.) Willd. in relation to geographical distribution and soil stress tolerances
Authors: Coulaud Joëlle , Barghi Nasrine , Lefèbvre Claude , Siljak-Yakovlev Sonja
Published: April 2011

Ten Armeria maritima (Mill.) Willd. populations (2n = 18) from contrasting ecogeographic situations were compared using 30 morphometric characters of karyotype and frequencies of abnormal metaphase and interphase cells in root-tip meristems. Despite the general symmetry and similarities, karyotypes of populations can be distinguished using a set of precise karyotypic features. Variations within populations mainly concerned the occurrence of satellites and weakly condensed areas of chromosomes. Total chromosome length measurements were congruent with flow cytometry estimates of DNA amounts. The geographical differentiation of European population karyotypes is in accordance with previously defined biochemical clustering. One population from Germany (ssp. bottendorfensis) is more similar to the American population (ssp. californica) than to the other European populations. Proposed trends of karyotype evolution are discussed in comparison with previous results on other character sets and taxonomic treatments. The species karyotype seems particularly unstable, as chromosome strong links at mitosis cause breaks generating chromosomal mutations and aneuploidy at the intra-individual level in all the populations. Abnormal interphase cells were found in most of the populations but were especially frequent in heavy-metal tolerant populations. The highest frequencies of karyotype aberrations were found in the American population and in populations adapted to soils with high levels of heavy metals or salinity. The frequency of interphase aberrations appeared to be related to the mean level of heavy-metal tolerance of populations. Consequently, the two types of abnormalities may originate from independent mechanisms. The genome behaviour of A. maritima is discussed with reference to recent findings concerning the effects of soil toxicity on plant genomes.Key words: Armeria maritima, karyotype, population differentiation, soil stress tolerance, mitotic aberrations, abnormal nuclei.
Wood-inhabiting microfungi isolated from Populus tremuloides from Alberta and northeastern British Columbia
Authors: Hutchison Leonard J
Published: April 2011

Forty-nine taxa of sporulating microfungi were isolated in pure culture from the bark and wood of living and recently cut stems of trembling aspen (Populus tremuloides) from several sites in central Alberta and northeastern British Columbia. Stems were either healthy, blue stained, or decayed, or else possessed cankers or black galls. Several ecological groupings of fungi were recognized, including wood-staining fungi (e.g., Ophiostoma piliferum), black-gall-associated fungi (e.g., Hyphozyma lignicola, Knufia cryptophialidica,Phoma etheridgei), canker-causing pathogens (e.g., Nectria cinnabarina, Tympanis spermatiospora, Valsa sordida), and fungi that could be referred to as endophytes. This latter group consisted of an assortment of fungi normally found in niches other than wood (e.g., Ciborinia whetzelii, Sporormiella similis), microfungi associated with decayed wood (e.g., Cryptosphaeria lignyota, Phialocephala fusca, Phialophora alba, Phialophora bubakii, or canker-causing fungi isolated from healthy tissue (e.g., Hypoxylon mammatum, Leucostoma nivea.Key words: microfungi, endophytes, Populus, aspen, wood, Ascomycota, hyphomycetes, coelomycetes.
Spittlebugs associated with actinorhizal host plants
Authors: Thompson Vinton
Published: April 2011

Actinorhizal plants are major hosts for many spittlebugs, particularly species of the genera Clastoptera and Aphrophora. World host records indicate that at least 20 spittlebug species have primary associations with at least 17 actinorhizal hosts in the genera Alnus, Casuarina, Ceanothus, Comptonia, Elaeagnus, and Myrica. The highly polyphagic spittlebug, Philaenus spumarius (L.), has also been observed in association with Hippophaë and Coriaria. Several other spittlebugs have minor associations with actinorhizal hosts.Key words: actinorhizal plant, spittlebug, host, nitrogen-fixing.
Polymerase chain reaction and hybridization on DNA extracted from soil as a tool forFrankiaspp. population distribution studies in soil
Authors: Nalin R , Normand P , Simonet P , Domenach A M
Published: April 2011

The distribution of Frankia populations in soil is usually studied by plant trapping in combination with genetic characterization. We compared this approach with the evaluation of population distribution by polymerase chain reaction (PCR) and hybridization. Seven populations of Frankia spp. strains, characterized by restriction by HaeIII of the nifD-nifK amplified fragments (nif-HaeIII profiles), were found to have different distribution in a soil column of 60 cm in depth. The nifD-nifK intergenic spacer and the 5'-part of the nifK gene were sequenced for one representative of the seven nif-HaeIII profiles to design specific oligonucleotide probes. The results on the distribution of Frankia populations by PCR amplification on DNA extracted directly from samples from three soil depths (10-20 cm; 30-40 cm; 50-60 cm) and hybridization with specific probes are congruent with the distribution observed by plant trapping.Key words: nif genes, soil, detection, Frankia, PCR, hybridization, plant trapping.
Polymerase chain reaction - restriction fragment length polymorphisms for assessing and increasing biodiversity ofFrankiaculture collections
Authors: Lumini Erica , Bosco Marco
Published: April 2011

During the last few years, some Frankia culture collections that maintained a large number of unidentified and uncharacterized Frankia strains were closed because of funding shortages. To reduce the costs of maintenance, we evaluated the biodiversity of half of the Frankia strains from our collection, by polymerase chain reaction - restriction fragment length polymorphisms (PCR-RFLPs) of nifD-nifK intergenic spacer and 16S-23S rDNA intergenic spacer regions. In this way we were able to reduce the number of strains without reducing the biodiversity of the whole collection. In general the nifD-nifK target proved to be more polymorphic than the rrn target. From 51 isolates of Elaeagnus frankiae, PCR-RFLP results allowed us to detect 13 identical strains, and to predict that the genomic species P8 of Akimov and Dobritsa (1992) very likely agrees with genomic species 5 of Fernandez et al. (1989). Moreover, we revealed genomic groups not yet described, as well as intraspecific variability. For Alnus frankiae, the polymorphisms shown by both the nif and the rrn PCR-RFLPs revealed three host plant species-specific subgroups inside Frankia alni. An expandable data base was created to serve as reference for future biodiversity evaluations on both culture collections and unisolated Frankia populations. It will be accessible by Internet at the International Frankia Website (http://www.unifi.it/unifi/distam/frankia/international.html).Key words: Frankia, PCR-RFLP, nifD-nifK intergenic spacer, rrn 16S-23S intergenic spacer, biodiversity, culture collections.
Differential effect of chitosan on root rot fungal pathogens in forest nurseries
Authors: Laflamme Philippe , Benhamou Nicole , Bussières Guy , Dessureault Michel
Published: April 2011

The effect of chitosan on the growth, morphology, and ultrastructure of Cylindrocladium floridanum Sobers & Seymour, Cylindrocarpon destructans (Zinss.) Scholten, Fusarium acuminatum Ellis & Everh., and Fusarium oxysporum Schlecht. was investigated in vitro. Chitosan was found to reduce the radial growth of all the fungi studied with some differences. Light microscope observations showed that chitosan induced morphological alterations to all fungi. Transmission electron microscope investigations revealed ultrastructural alterations such as increased vacuolation, retraction, and alteration of the plasma membrane, cell wall thickening, hyphal distortion, and cytoplasm aggregation. The possible modes of action of chitosan are discussed.
Chrysomyxa rust: morphology and ultrastructure of D-haustoria, uredinia, and telia
Authors: Berndt Reinhard
Published: April 2011

An electron- and light-microscopic study revealed that D-haustoria of Chrysomyxa rhododendri (DC.) De Bary and Chrysomyxa pirolata Winter were pedicellate and had a more or less tuber-shaped haustorial body. The haustorial necks were wrapped by a fold of the extrahaustorial membrane (velopedunculate haustorial type). The aecioid uredinia of Chrysomyxa rhododendri and Chrysomyxa empetri (Pers.) Schröter were covered by a one-layered peridium of the pucciniastreous type. In Chrysomyxa pirolata, young uredinia were covered by one to three layers of sterile fungal cells. In all investigated species, urediniospore mother cells were formed blastically by proliferating basal cells. Subsequent cell divisions of the urediniospore mother cells led to the formation of urediniospores and intercalary cells. In Chrysomyxa rhododendri, the intercalary cells had a pronounced proximal thickening of the radial wall. In Chrysomyxa pirolata andChrysomyxa empetri, the wall was uniformly thickened. Telial morphology of Chrysomyxa rhododendri and Chrysomyxa pirolata was very similar. In Chrysomyxa rhododendri, the probasidia formed true chains without intercalary cells, and they are probably of thallic origin. During maturation they partly separated at their septa by dissolution of the primary wall of the septa between the probasidia. No sterile elements were present in the telia. The occurrence of velopedunculate D-haustoria and a uredinial peridium of the pucciniastreous type confirm the systematic position of Chrysomyxa close to pucciniastreous rusts, Cronartium, and Coleosporium within Melampsoraceae.
Threatened dry grasslands in the continental boreal forests of Wood Buffalo National Park: commentary
Authors: Timoney Kevin P
Published: April 2011

There are three primary types of graminoid-dominated communities in or near Wood Buffalo National Park, Canada: freshwater meadows and marshes composed of Calamagrostis canadensis (Michx.) Beauv., Carex atherodes Spreng., Carex aquatilis Wahlenb., Scolochloa festucacea (Willd.) Link, and Poa L.; saline meadows composed of Hordeum jubatum L., Puccinellia nuttalliana (Schult.) A.S. Hitchc.,Agropyron trachycaulum (Link) Malte, Calamagrostis stricta (Timm) Koeler, and Calamagrostis inexpansa A. Gray; and dry grasslands composed of Agropyron trachycaulum, Stipa L., Carex siccata Dewey, Carex obtusata Lilj., and Koeleria macrantha (Ledeb.) J.A. Schultes f. Except for the Peace Point area, it is not known whether dry grasslands have declined in areal extent. Including various wetlands under "dry grasslands", and concluding that these areas no longer support dry grassland is misleading. Dry grasslands exist in Wood Buffalo National Park, but most graminoid-dominated communities in the park are, and have been, freshwater and saline meadows and marshes. A clear understanding of the ecological factors operating in these different ecosystems is critical to informed management.Key words: fire, grassland, prairie, vegetation, wetland, Wood Buffalo National Park.
Dry grasslands in Wood Buffalo National Park: reply
Authors: Schwarz A G , Wein Ross W
Published: April 2011

In examining dry grassland areas of Wood Buffalo National Park (WBNP), we used vascular plant indicators commonly found in the grassland landscapes in the southern and central parts of the Prairie Provinces. With distance northward the landscapes become increasingly tree-dominated and the dry grasslands have fewer dry grassland indicator species (about 40 in the area of WBNP) and become smaller in size (about 1 ha in WBNP). Key species are Stipa comata Trin & Rupr., Stipa curtiseta (A.S. Hitchc.) Barkworth, and Stipa columbiana Macoun on the drier sites. Paleontological records and historical documents suggest that these remnant dry grasslands must expand during decades of drought and must contract during decades of higher summer rainfall. We hypothesize that fires might enhance dry grassland expansion by stressing and killing trees and shrubs. Southern dry grassland vascular plant species represent over 7% of the total in WBNP. It is reasonable to hypothesize that these represent special ecotypes that deserve special protection through prescribed burning.Key words: remnant grasslands, Stipa spp., climate change.
Species richness and abundance of ectomycorrhizal basidiomycete sporocarps on a moisture gradient in the Tsuga heterophylla zone
Authors: O'Dell Thomas E , Ammirati Joseph F , Schreiner Edward G
Published: April 2011

Sporocarps of epigeous ectomycorrhizal fungi and vegetation data were collected from eight Tsuga heterophylla (Raf.) Sarg. - Pseudotsuga menziesii (Mirb.) Franco stands along a wet to dry gradient in Olympic National Park, Washington, U.S.A. One hundred and fifty species of ectomycorrhizal fungi were collected from a total sample area of 2.08 ha. Over 2 years, fungal species richness ranged from 19 to 67 taxa per stand. Sporocarp standing crop ranged from 0 to 3.8 kg/ha, averaging 0.58 kg/ha, 0.06 kg/ha in spring and 0.97 kg/ha in fall. Sporocarp standing crop and fungal species richness were correlated with precipitation. These results demonstrated that ectomycorrhizal fungal sporocarp abundance and species richness can be partly explained in terms of an environmental gradient.
An attempt to explain the distribution of the tree species composing the riparian forests of Lake Duparquet, southern boreal region of Quebec, Canada
Authors: Denneler Bernhard , Bergeron Yves , Bégin Yves
Published: April 2011

The objective of this study was to evaluate the most important environmental factors determining the distribution of tree species within the riparian zone of Lake Duparquet, located in the southern boreal region of Quebec, Canada. Occurrence and relative basal area of 10 species were recorded within an altitudinal range of 200 cm above mean water level along 95 transects. Stepwise logistic regression and canonical correspondence analyses were performed on the overall data set as well as separately for the five geomorphological shore types distinguished (depositional flats, floodplains, beaches, terraces, and rock outcrops). The elevation gradient, representing seasonal floodings, is the main factor determining the distribution of the species. The differences between the geomorphological shore types with respect to composition and arrangement of the arborescent vegetation along the elevation gradient are at least partially explained by surficial substratum, topography, aspect, and fire. Exposure to wave activity seems to be of minor importance only. However, since they are the driving force of erosion and sedimentation, the waves are to a great part responsible for the morphological differentiation of the shoreline. The distribution of the tree species along a characteristic physiographic cross-section is illustrated for each geomorphological shore type.
Optical properties of leaves in relation to anthocyanin concentration and distribution
Authors: Neill Sam , Gould Kevin S
Published: April 2011

We have tested the tacit assumption that the location of anthocyanic cells within a leaf affects the quality and quantity of light that is absorbed. Leaf optics are described for Quintinia serrata A. Cunn., a native New Zealand tree that is polymorphic for anthocyanin distribution and concentration. Anthocyanin production enhanced the absorptance of green-yellow wavelengths in proportion to pigment concentration. The reflectance of red light was independent of leaf anthocyanin content. Variation in the location of pigmented cells could not account for differences in leaf optics. The effects of anthocyanin on PAR absorptance were consistent across six further, unrelated species that bore red leaves. We conclude that anthocyanin concentration, rather than its histological distribution, has the greater impact on leaf optical properties.
Sulphur dioxide effects on cell structure and photosynthetic performance in the liverwort Frullania dilatata
Authors: Gimeno Cristina , Deltoro Vicente I
Published: April 2011

The effects of SO2 exposure, carried out in controlled-environment cuvettes, on the photosynthetic performance of the liverwort Frullania dilatata (L.) Dum. were investigated by means of chorophyll a fluorescence induction kinetics and gas-exchange measurements. Additionally, visible-injury symptoms developing in leaves as a result of exposure to the pollutant were quantified and described. The adverse effects of SO2 on photosynthesis could be seen as (i) a decreased electron flow through photosystem II (PSII), (ii) an increased degree of closure of PSII centres, (iii) a lowered capacity for dissipative processes, and (iv) reduced net CO2 assimilation rates. Additionally, SO2 induced severe cell injury that ranged from cells without oil bodies to cells with collapsed plasma membrane and disorganized organelles. The distribution pattern of injuries in the shoots ofF. dilatata suggests that SO2-induced damage is related to the degree of direct exposure to the pollutant. It is possible that, because this liverwort grows in dense patches with overlapping branches, some protection is conferred to basal leaves.Key words: Frullania dilatata, chlorophyll fluorescence, sulphur dioxide, fumigation, cellular injury.
Physiology of two monocentric chytrids: comparative nutritional studies of Entophlyctis sp. and Entophlyctis aureus (Chytridiales)
Authors: Hassan Mozaffar W , Catapane Edward J
Published: April 2011

This paper describes physiological characteristics of Entophlyctis sp. and Entophlyctis aureus Fisher. The two chytrids grew best at 20-25°C in a chemically defined medium, and at 20-30°C in nutrient solutions containing bactotryptone and glucose. The range of pH that supported good growth was 6.5-8.5. Both organisms utilized ammonium and nitrate nitrogen, several amino acids, and glucose, fructose, mannose, maltose, and raffinose. They were prototrophic with respect to vitamin requirements, and vitamin mixture at a concentration of 10 µg/mL inhibited growth. They are physiologically similar to Entophlyctis confervae-glomeratae (Cienkowski) Sparrow.Key words: Entophlyctis sp., Entophlyctis aureus, Entophlyctis confervae-glomeratae.
Inoculation of stumps with Hypholoma fasciculare as a possible means to control armillaria root disease
Authors: Chapman Bill , Xiao G
Published: April 2011

Hypholoma fasciculare (Huds. ex Fr.) Kummer was paired with Armillaria ostoyae (Romagn.) Herink in a variety of ways in the laboratory and then it was inoculated onto A. ostoyae infected stumps in the field. The ability of H. fasciuclare colonies to overrun A. ostoyae colonies in culture was confirmed. Hypholoma fasciculare fully colonized discs of tree roots where A. ostoyae was well established, and prevented A. ostoyae from occupying root segments when both fungi were introduced simultaneously. A simple method for inoculating H. fasciculare into stumps is described, and data supporting successful field inoculations are presented. The ability of H. fasciculare to invade freshly killed stumps, even those occupied by Armillaria, is demonstrated, and it is speculated that the ability of this saprophyte to invade fresh stumps is dependent upon its inoculum potential.Key words: biocontrol, woody debris, fungal warfare, Armillaria ostoyae.
Préparation d'un substrat de culture pour le strophaire (Stropharia rugoso-annulata) par trempage de résidus ligno-cellulosiques agricoles
Authors: Bonenfant-Magné Michèle , Magné Christian , Lemoine Cécile
Published: April 2011

Because of the enzymatic make-up of Stropharia, a cultivated and edible mushroom, it is capable of using agricultural wastes as substrates for growth. Different substrates and methods of preparation are compared in order to improve the resistance of the mushroom to fungal contamination by reducing soluble carbon and nitrogen content. The substrates (wheat straw, corn stalk, or wastes from pea plants) were soaked at various temperatures and durations in order to eliminate soluble nutrients. High temperatures are more efficient for a rapid depletion of free nitrogen compounds. The best substrate used for the first time in mushroom cultivation was the agricultural waste from Pisum. Because of its naturally high content of soluble nutrients, this substrate needs to be soaked in hot water to reduce contaminations. Yields of Stropharia (220 g/kg) are higher and more regular than those obtained on conventional substrate (straw). On corn stalk, a high contamination rate was found, as well as relatively poor yields.Key words: mushroom, Stropharia, substrate, waste, yield, fungal contamination.
Pollen morphology in Lyperia (Scrophulariaceae) and related taxa with a multivariate analysis of the major patterns of pollen character variation in tribe Manuleae
Authors: Argue Charles L
Published: April 2011

The pollen of all six species of Lyperia (Scrophulariaceae, tribe Manuleae) was investigated by light microscopy and scanning electron microscopy of whole and fractured grains. Pollen grains in Lyperia antirrhinoides (L.f.) Hilliard, Lyperia formosa Hilliard, Lyperia tenuiflora Benth., and Lyperia violacea (Jarosz) Benth. differed from those in Lyperia tristis (L.f.) Benth. and Lyperia lychnidea (L.) Druce in number and length of colpi, sculpturing of the colpus margin, reduction of apocolpial lumina size, reduction of exine thickness toward the colpi, ornamentation of the outer nexine surface, arrangement of columellae beneath the muri, direction of cross-sectional compression in elliptical muri, and relative dimensions of the muri and columellae. Pollen grains from 50 representative species of the putatively related genera Sutera and Jamesbrittenia were also examined. Correlations among quantitative pollen characters of tribe Manuleae and the Sutera complex were investigated by principal components analysis. Morphological similarities in the pollen of Lyperia, genera of the Sutera complex, and other Manuleae were summarized by ordination of the principal components data and (or) cluster analysis. The pollen grains of L. lychnidea and L. tristis differed from those of other Lyperia and stood apart from those of Jamesbrittenia, Sutera, and all other Manuleae. Pollen morphology in Sutera and Jamesbrittenia intergrades with that in tricolporate species of Lyperia.Key words: pollen morphology, Scrophulariaceae, Lyperia, Jamesbrittenia, Sutera.
The paleomagnetic significance of new U-Pb age data from the Molson dyke swarm, Cauchon Lake area, Manitoba
Authors: Halls Henry C , Heaman Larry M
Published: April 2011

U-Pb geochronology, paleomagnetism, and petrography indicate that the Molson dyke swarm, along the western margin of the Superior craton, is a composite of at least two ages of intrusion. The more extensive younger dyke set, the Molson swarm sensu stricto, generally has a 030° trend, is mainly pyroxenitic to noritic with subordinate diabase, and has been related to rifting in a back-arc environment during closure of the Manikewan ocean at about 1920-1800 Ma which culminated in the Trans-Hudson Orogen. A U-Pb zircon age from one of these dykes, located at Cauchon Lake, indicates emplacement at 1877+7– 4, similar to two previous U-Pb age determinations on Molson dykes. Another dyke from Cauchon Lake yields a baddeleyite-zircon U-Pb date of 2091 ± 2 Ma and appears to be part of an older, mainly diabasic suite of east-northeast-trending dykes that may represent a continental rifting episode that preceded the opening of the Manikewan ocean. The new U-Pb age data require a revision to the interpretation of the A, B, and C paleomagnetic poles previously reported from Molson dykes. The A pole (16.1°N, 96.5°W), initially assigned an age of 1883 Ma, is now considered to be younger and derived from a Paleoproterozoic overprint associated with the Trans-Hudson Orogen at about 1700-1800 Ma. Pole B (27.1°N, 140.8°W) from the Molson swarm sensu stricto is now regarded as primary, and dated at 1880 Ma. Pole C can be subdivided into two poles, one virtually the same as B but of opposite polarity (and therefore about 1880 Ma old) and a new pole (53°N, 180°W) derived from a primary remanence and dated at 2091 Ma. The new paleomagnetic interpretations may have important consequences for tectonic models of the Trans-Hudson Orogen and for Paleoproterozoic continental reconstructions.
Nd isotopic characteristics of terranes within the Avalon Zone, southern New Brunswick
Authors: Samson Scott D , Barr Sandra M , White Chris E
Published: April 2011

Nd isotopic data are presented for rock units in four terranes within the traditional Avalon Zone of southern New Brunswick. Initial εNd values for igneous rocks within the Caledonia terrane range from -1.6 to +4.6, whereas values for sedimentary rocks range from -8.4 to +3.6. A granite within the Kingston terrane has εNd(438 Ma) = +4.0. Nd isotopic compositions for the Kingston and Caledonia terranes are similar to those of the Mira terrane in Cape Breton Island, the Antigonish Highlands of Nova Scotia, and plutonic rocks of eastern Newfoundland. Each of these regions may be a dismembered part of a single terrane, the Avalon terrane sensu stricto. Initial εNd values for rocks from the Brookville terrane range from -1.3 to +2.8. The Coverdale anorthosite within the Brookville terrane has a present day εNd value of -12.1 and a depleted mantle model age of 1.3 Ga, similar to Mesoproterozoic anorthosites in Laurentia. Clastic sedimentary rocks in the Green Head Group have εNd(750 Ma) values of -2.0 and -10.9. Viewed as a whole, the Brookville terrane is isotopically more evolved than the Caledonia terrane. Initial εNd values for rocks in the New River terrane range from -2.9 to 0.0. The Nd isotopic composition of the Brookville and New River terranes are thus similar to one another and have isotopic character similar to that of the Bras d'Or terrane of Cape Breton Island. It is suggested that all three regions belong to a single terrane (Bras d'Oria).