bluuebunny/crossref_metadata_2025 huggingface dataset:
Germination studies of three dwarf shrubs (Vaccinium, Ericaceae) of Northern Hemisphere coniferous forests
Authors: Baskin Carol C , Milberg Per , Andersson Lars , Baskin Jerry M
Published: April 2011

Freshly matured seeds of the dwarf shrubs Vaccinium myrtillus L., Vaccinium vitis-idaea L., and Vaccinium uliginosum L. from various sites in coniferous forests in Sweden were tested for germination before and after cold stratification. In initial tests, seeds of V. myrtillus and V. vitis-idaea germinated to 62100% in light at 20:10 and (or) at 25:15°C with few (112%) or no seeds germinating at 15:5(6)°C; however, after 12 or 20 weeks of stratification germination increased significantly in light at 15:5(6)°C. Thus, seeds of these species are conditionally dormant at maturity. Of seeds sown outdoors in southern Sweden on various dates in summer, 120% of V. myrtillus and 02% of V. vitis-idaea germinated before winter. Seeds of neither species germinated during late May, when minimum temperatures were about 710°C, but they did germinate after minimum temperatures increased to [Formula: see text] 10°C. Although stratification increased germination percentages of V. myrtillus and V. vitis-idaea seeds at 15:5(6)°C, more than 2 weeks of incubation at this temperature was required for germination. Thus, even after habitat temperatures have reached the minimum range for germination of nondormant seeds, a slow rate of germination at low temperatures may prevent stratified seeds of both species from germinating in the field in early spring. Nonstratified seeds of V. uliginosum germinated to a maximum of 5% in light and of 7% in darkness, but after 12 weeks of stratification, seeds germinated to 4995% in light and to 160% in darkness at the three temperature regimes. Most seeds of V. uliginosum are dormant at maturity, and they come out of dormancy during stratification in winter. By spring, seeds of V. uliginosum germinate over the same range of temperatures as those of V. myrtillus and V. vitis-idaea, but seeds of V. uliginosum germinate faster at 15:5(6)°C than those of the other two species.Key words: blueberry seed germination, cold stratification, Ericaceae, seed dormancy, seed germination, Vaccinium.
The 5S rRNA gene units in the native New World annualHordeumspecies (Triticeae: Poaceae)
Authors: Baum Bernard R , Johnson Douglas A
Published: April 2011

We have employed a polymerase chain reaction (PCR) based approach to amplify 5S rDNA sequences from 20 accessions representing five Hordeum species native to the Americas. Sequence analysis of 88 clones revealed three sets of orthologous sequences in Hordeum pusillum Nutt. and two sets in the other four species. The long H1 unit class, previously known in Hordeum bulbosum L., Hordeum marinum L. s.l., Hordeum murinum L. s.l., Hordeum spontaneum Boiss., and Hordeum vulgare L., was found also in Hordeum depressum (Scribner & Smith) Rydberg and in H. pusillum; however, the majority of the sequences fell within two new classes of orthologous sequences. Sequences of the long H2 unit class were found in four species but not in H. depressum. Sequences of the long Y2 unit class were found in all five species. The long H2 and long Y2 unit classes appear to be unique to this group of five, mostly annual, North and South American species. Cladistic analysis of the orthologous sequences from the species with the long H1 unit class places the long H1 sequence of Hordeum flexuosum Steudel in the same clade with H. murinum, whereas H. depressum is more closely related to the perennial species, Hordeum bogdanii Wilenski and H. bulbosum. This association differs from previously described species relationships and it may be that the gene tree differs from the species tree. A cladistic analysis of paralogous sequences of the two new unit classes defined in this study together with the long H1, the long Y1 and the long X2 unit classes uncovered in previous work in Hordeum, was performed. Based upon these analyses, we hypothesize that the possible order of divergence was first the division into two branches leading to the long H1 unit class and the long H2 unit class; the lineage leading to the long H2 class was further divided to give rise to branches leading to the long Y1, the long Y2 and the long X2 classes.Key words: 5S rDNA, genomes, haplomes, unit classes, Hordeum, Triticeae.
Detecting exodermal Casparian bands in vivo and fluid-phase endocytosis in onion (Allium cepa L.) roots
Authors: Cholewa Ewa , Peterson Carol A
Published: April 2011

Maturation of the exodermis involves development of a Casparian band, a structure that blocks the apoplastic movement of ions. The position at which this band is formed is not readily predictable, since it depends on species and growing conditions. Until now, Casparian band detection necessitated destructive methods which involved sectioning or clearing the roots. In the present study, a method for detecting exodermal Casparian bands in vivo is presented. Undisturbed onion roots were incubated for 2 h in 0.1% 8-hydroxy-1,3,6-pyrenetrisulphonate (PTS) and then thoroughly rinsed in running water. Under UV light, the tracer was evident in the cortex of the root regions with an immature exodermis but not in older regions of the root where the Casparian band had developed. PTS had entered the protoplasts of the cortical cells in the younger part of the root and had not been removed by rinsing. The first order kinetics of uptake, and insensitivity to external pH and probenecid indicated that PTS entered the cell by fluid-phase endocytosis. PTS-loaded vesicles that released their contents into the vacuole were seen using confocal laser scanning microscopy. When applied to undisturbed, whole root systems, PTS was not detected in aqueous extracts of the leaves. Thus, there is no major apoplastic bypass in healthy onion roots.Key words: exodermis, Casparian bands, apoplastic bypass, PTS, fluid-phase endocytosis.
DNA content for Asian pines parallels New World relatives
Authors: Joyner Karen L , Wang Xiao-Ru , Johnston J Spencer , Price H James , Williams Claire G
Published: April 2011

This hypothesis is based on an observed correlation between DNA content and thermal regime for fish, zooplankton, salamanders, and some flowering plants. The Asian pine results provided no support for the latitudinal hypothesis; Asian tropical pine species did not have smaller genomes than their temperate or boreal relatives. DNA content of haploid megagametophyte tissue varied from 21.85 pg/C for hard pine Pinus densiflora Sieb. & Zucc. to 29.59 pg/C for soft pine Pinus bungeana Zucc. Pinus merkusii Jung. & De Vriese (29.63 pg/C) was the exceptional hard pine, with a genome size larger than many soft pines. The mean DNA content of Asian soft pines exceeded Asian hard pines (Δ 3.22 pg/C), a parallel to the previously reported trends for New World pines. No continental effect was detected. Based on 46 pines species sampled in centers of species diversity in Asian and the New World, soft pines had mean DNA content which exceeded hard pines by 4.97 pg/C.Key words: gymnosperms, conifers, laser flow cytometry, megagametophytes, C values, phylogeny.
Land cover change in eastern Kansas: litter dynamics of closed-canopy eastern redcedar forests in tallgrass prairie
Authors: Norris Mark D , Blair John M , Johnson Loretta C
Published: April 2011

In the Great Plains region, eastern redcedar (Juniperus virginiana L.) abundance has increased dramatically in areas historically occupied by tallgrass prairie. This shift in dominant vegetation is likely to be accompanied by changes in ecosystem structure and function, including quantity, quality, and location (above- vs. below-ground) of litter inputs and subsequent effects on decomposition dynamics. The purpose of this study was to quantify and compare patterns of litterfall and decomposition in mature redcedar forests and adjacent prairie. Annual redcedar litterfall was 500 g·m-2·year-1, a large increase in foliar litter inputs compared with annually burned grassland (52 g·m-2·year-1). Using a reciprocal transplant decomposition study with four substrates, redcedar leaves and roots, and big bluestem (Andropogon gerardii Vitman) foliage and roots, we found marginal habitat effects, but greater differences between species, presumably owing to litter quality (including both C:N and lignin content). Decay rates were significantly higher in the prairie relative to the forest for each substrate. Additionally, within any particular habitat, grass litter had significantly faster decay rates than forest litter. These results suggest a shift in patterns of litter input and decomposition processes with afforestation of tallgrass prairie, which may result in long-term changes in C sequestration and storage.Key words: litter dynamics, eastern redcedar (Juniperus virginiana), big bluestem (Andropogon gerardii), decomposition, tallgrass prairie, nitrogen immobilization.
Mise en évidence d'une régulation de l'efflux de NO3 racinaire par la partie aérienne chez quatre cultivars de blé tendre (Triticum aestivum L.), Sais, Jouda, Marchouch et Khair : influence de la lumière
Authors: Abdellaoui Abdelfattah , Larhnim Asia , Talouizte Ahmed
Published: April 2011

Nitrate exsorption in relation to light was studied in four wheat (Triticum aestivum L.) cultivars, Sais, Jouda, Marchouch, and Khair, using four experimental treatments: intact plants, excised roots, defoliated plants, and decapitated plants. Data show that nitrate exsorption was dramatically reduced from excised roots compared to controls. This efflux reduction was also observed from the roots of decapitated plants. On the contrary, defoliation triggered a significant increase in the quantity of exsorbed NO3, as compared to intact plants. This increased efflux was much more dramatic when defoliated plants were exposed to darkness; nitrate exsorption from roots was then 8 to 10 times larger than from excised roots. In 21-day-old wheat plantlets, the aboveground parts are the main site for efflux regulation at the root level. Both leaves and apex are the aboveground organs responsible for this regulation. Indeed, the efflux was reduced by the leaves and, on the contrary, stimulated by the apex. Light was involved in controlling this efflux. This control involves a flow, between the aboveground parts and the roots, of two types of factors, one of which (or both) being sensitive to light. The first factor is of apical origin, whereas the second is of foliar origin. However, the chemical nature of these two types of photosensitive factors involved in NO3 ions efflux regulation remains to be determined.Key words: nitrate, efflux, light, darkness, common wheat.[Journal translation]
Phylogenetic relationships in Neonectria species having Cylindrocarpon anamorphs inferred from mitochondrial ribosomal DNA sequences
Authors: Mantiri Feky R , Samuels Gary J , Rahe James E , Honda Barry M
Published: April 2011

Mitochondrial small subunit (mtSSU) rDNA sequences elucidated phylogenetic relationships in Neonectria Wollenw. (anamorphs = Cylindrocarpon Wollenw.; Ascomycetes, Hypocreales). Twelve isolates representing seven species in five taxonomically informal groups of Neonectria were subjected to phylogenetic analysis. Fusarium inflexum R. Schneid. (teleomorph: Gibberella) and Nectria cinnabarina (Fr.) Fr. (= Nectria s.str.) were outgroups. All of the Neonectria species formed a strongly supported clade with respect to the outgroups, indicating a single ascomycete genus for the holomorphs of Cylindrocarpon. Within the Neonectria clade there were three well-supported subclades that only partially corresponded to phenotype-defined groups. DNA sequence divergence among the twelve Neonectria isolates, 2.3-7.4%, was sufficient to resolve them. The results suggest that the mtSSU rDNA region is appropriate for phylogenetic analysis of Neonectria and Cylindrocarpon. The following new combinations are proposed: Neonectria coronata, Neonectria discophora, Neonectria neomacrospora, Neonectria radicicola, Neonectria rugulosa, Neonectria veuillotiana.Key words: Ascomycetes, Hypocreales, Nectria, systematics, tree pathogens.
Bryophyte community structure in a boreal poor fen: reciprocal transplants
Authors: Mulligan Roisín C , Gignac L Dennis
Published: April 2011

The ability of four boreal bryophytes (Sphagnum angustifolium (C. Jens ex Russ.), Sphagnum fuscum (Schimp.) Klinggr., Sphagnum magellanicum Brid., and Pleurozium schreberi (Brid.) Mitt.) to live in each others' habitats was examined in a 1-year reciprocal transplant experiment conducted in a poor fen peatland in northern Alberta, Canada. Growth in length was determined by measuring increase in shoot length, and growth in dry weight was determined by subtracting final dry weight from initial predicted dry weight. Species tolerance ranges, which approximate to fundamental niches, were determined by the significant differences in growth among the species. Stepwise regression analyses indicated that depth to water was the most important factor for all species except S. fuscum. Pleurozium schreberi exhibited the narrowest potential distribution, indicating that its present distribution is likely the result of habitat limitation. Although S. magellanicum and S. angustifolium exhibited wide potential ecological amplitude, the distributions of these species are partially limited by habitat. Sphagnum fuscum was able to grow in all habitats, and its distribution is not limited by any of the habitat factors measured.Key words: peatland, moss, community structure, Sphagnum, Pleurozium schreberi, niche.
Distribution of leaf orientations in six conifer species
Authors: Barclay Hugh J
Published: April 2011

Leaf angle distributions are important in assessing both the flexibility of a plant's response to differing daily and seasonal sun angles and also the variability in the proportion of total leaf area visible in remotely sensed images. Leaf angle distributions are presented for six conifer species, Abies grandis (Dougl. ex D. Don) Lindl., Thuja plicata Donn. ex D. Don, Tsuga heterophylla (Raf.) Sarg., Pseudotsuga menziesii (Mirb.) Franco, Picea sitchensis (Bong.) Carr. and Pinus contorta Dougl. ex Loud. var. latifolia. The leaf angles were calculated by measuring four foliar quantities, and then the distributions of leaf angles are cast in three forms: distributions of (i) the angle of the long axis of the leaf from the vertical for the range 0180°; (ii) the angle of the long axis of the leaf for the range 090°; and (iii) the angle of the plane of the leaf for the range 090°. Each of these are fit to the ellipsoidal distribution to test the hypothesis that leaf angles in conifers are sufficiently random to fit the ellipsoidal distribution. The fit was generally better for planar angles and for longitudinal angles between 0° and 90° than for longitudinal angles between 0° and 180°. The fit was also better for Tsuga heterophylla, Pseudotsuga menziesii, Picea sitchensis, and Pinus contorta than for Abies grandis and Thuja plicata. This is probably because Abies and Thuja are more shade tolerant than the other species, and so the leaves in Abies and Thuja are preferentially oriented near the horizontal and are much less random than for the other species. Comparisons of distributions on individual twigs, whole branches, entire trees, and groups of trees were done to test the hypothesis that angle distributions will depend on scale, and these comparisons indicated that the apparent randomness and goodness-of-fit increased on passing to each larger unit (twigs up to groups of trees).Key words: conifer, leaf angles, ellipsoidal distribution.
Sur l'organisation phytochimique de formations prairiales permanentes
Authors: Lebreton Philippe , Jeangros Bernard , Gallet Christiane , Scehovic Jan
Published: April 2011

Organic and mineral components have been analysed on 18 dicotyledonous species of permanent grassland communities. Multivariate analysis revealed an opposition between a macromolecular pool (cellulose and lignin) and a nutrient pool (potassium and phosphorus, nitrogen). The first pole is characterized by Tragopogon pratensis L. (Compositae) and Galium mollugo L. (Rubiaceae), the second by Anthriscus sylvestris (L.) Hoffm. (Umbelliferae) and Geranium sylvaticum L. (Geraniaceae). The most thermo-helio-xerophilous species (Knautia arvensis (L.) Coult and Tragopogon pratensis) belong to the first group, whereas the second group includes the cool-environment species (like Alchemilla xanthochlora Roth.), which reveals an ecophysiological determinism. Moreover, correlations between the biochemical and ecological structure, and other interrelated parameters, including sclerophylly, have been shown. Compared to lignous and sempervirent plant communities, the grassland species have lower phenolic and lignin contents but higher glucide and nutrient (potassium and phosphorus) contents, which is in accordance with their food value. For this herbaceous community, the C/N ratio indicates the same general equilibrium between cell-wall macromolecules and nitrogen than for two other plant communities (mainly ligneous) previously studied, with some differences revealing distinct trends from the same general metabolic sheme.Key words: dicotyledonous plant communities, biochemical organization, C/N ratio, ecophysiology.
Virulence in populations of Puccinia graminis f.sp. tritici in Canada from 1952 to 1998: a non-parametric analysis
Authors: Harder D E , Baum B R , McCallum B D
Published: April 2011

Six hundred and twenty six isolates of Puccinia graminis f.sp. tritici that were collected and stored between 1952 and 1998 were identified using 32 single-gene differential wheat lines. These pathotypes represented isolates from field surveys, nursery collections, and from greenhouse experiments. Infection type data was converted to a binary data matrix with a 0 (resistant) or 1 (susceptible) numeral assigned to each isolate for each differential line. The Gower coefficient of similarity was determined for every pair of isolates, then they were clustered using the non-parametric cluster analysis MODECLUS. Eight significantly different clusters were obtained from an overall heterogeneous database of 405 unique pathotypes representing all regions of Canada. For further analysis, isolates obtained only from field survey collections were selected and divided by region of collection into Pacific (45 pathotypes), prairie (191 pathotypes), and eastern Canadian (83 pathotypes) populations. The Pacific population, which was both sexually and asexually reproducing, consisted of two clusters. The prairie population, strictly asexually reproducing, consisted of nine clusters, and the eastern population, which may be partially sexually reproducing, had three clusters. The Pacific population was shown to be significantly different from the prairie and eastern populations, while the prairie and eastern populations were less distinct. The pathotype composition of the regional clusters, reliability of cluster segregation using non-parametric analysis, and usefulness of the data to contribute to a revised nomenclature of P. graminis f.sp. tritici, are evaluated.Key words: stem rust, black rust, wheat, specific virulence.
"Helminthosporium" asterinum, Polydesmus elegans, Imimyces, and allies
Authors: Shoemaker R A , Hambleton Sarah
Published: April 2011

Helminthosporium asterinum Cooke (=Helminthosporium papulosum Anth. Berg, Helminthosporium phomatae Dearn. & House) is redescribed and transferred to Ellisembia because of distinctions in the kind of conidiogenous cell. Polydesmus elegans Durieu & Mont. is redescribed and Helminthosporium densum Sacc. & Roum. and Taeniolella bilgramii S.S. Reddy & S.M. Reddy are its synonyms. Imimyces A. Hern.-Guit. & B. Sutton, typified by H. densum Sacc. & Roum., is a synonym of Polydesmus Mont. Consequent to the exclusion of the type species of Imimyces, a new genus, Imicles, typified by Helminthosporium leptosporum Sacc. & Roum., is proposed for the residue of species formerly included in Imimyces.Key words: apple, pear, black-pox, Corynespora, Corynesporina, Sporidesmium.
Phylogenetic relationships in Leptographium based on morphological and molecular characters
Authors: Jacobs K , Wingfield M J , Wingfield B D
Published: April 2011

Species of Leptographium Lagerberg & Melin are characterized by mononematous conidiophores with dark stipes and conidiogenous apparatuses with complex series of branches. These fungi generally inhabit woody substrates, are associated with bark beetles (Coleoptera: Scolytidae) and cause blue-stain in conifers. Few phylogenetic studies have been conducted on Leptographium species, and those that have been undertaken have been focused on a small number of species. The objective of this study was to investigate the phylogenetic relationships among species in Leptographium based on partial DNA operon sequences and to ascertain whether morphological characters are congruent with DNA-based phylogeny. Morphological characters were analyzed and compared with results from DNA sequence analysis. Results indicate that there are three groups within Leptographium based on DNA sequence analysis. There was, however, no congruence between these groups and those emerging from morphological characters. Data from this study strongly support the connection between Leptographium and Ophiostoma Sydow & Sydow. They also provide us with an objective means to confirm the identity of many Leptographium species that are difficult to distinguish based on morphological characters.Key words: Leptographium, phylogeny, morphology, Ophiostoma, rRNA.
Effects of two cryopreservation techniques on viability and pathogenicity of entomophthoralean fungi
Authors: López Lastra Claudia C , Hajek Ann E , Humber Richard A
Published: April 2011

The difficulties in long-term storage of cultures of Entomophthorales create a barrier to working with these entomopathogenic fungi. Relatively few laboratories have access to controlled cooling apparatus and storage in liquid nitrogen, but a simpler, more affordable technique to store cultures at 80°C is available. We compared viability among three entomophthoraleans and pathogenicity for one species for both storage techniques over 10 months. Fluorescent staining for viability demonstrated that there was no statistically significant difference by storage treatment for all three fungi. Although cells of Entomophaga aulicae (Reichardt in Bail) Humber decreased in viability after 8 and 10 months of storage, similar declines were not seen with Entomophaga maimaiga Humber, Shimazu & Soper or Zoophthora radicans (Brefeld) Batko. Bioassays of E. maimaiga against gypsy moth larvae, Lymantria dispar (L.), demonstrated no differences in time to death or percent mortality after 10 months of storage by either method. However, after 10 months, fewer cadavers of larvae injected with cultures stored at 80°C abundantly produced conidia. Our findings suggest that for these isolates from three species of Entomophthorales, storage at 80°C after a simple freezing protocol had a minor effect compared with storage at 196°C, but some cultures were more sensitive to prolonged freezing than others.Key words: Entomophaga aulicae, Entomophaga maimaiga, Zoophthora radicans, storage, in vitro culture, entomopathogenic fungi.
Analysis of phenotypic and genetic variations among populations of Oryza malampuzhaensis show evidence of altitude-dependent genetic changes
Authors: Thomas George , Joseph Latha , Varghese George , Kalyanaraman Sreejayan K , Kuriachan Philomena
Published: April 2011

Oryza malampuzhaensis Krish. et Chand., one of the tetraploid taxa in the genus Oryza (Poaceae), is geographically restricted to Western Ghats, southern India. This is one of the poorly understood taxa in the genus, and not much is known about the nature and distribution of its genetic diversity. Five individuals each were selected randomly from 11 populations of O. malampuzhaensis from different altitudinal habitats and were grown in a common-garden experiment for 3 years (1994-1997). Sixty morphological traits and 87 random amplified polymorphic DNA (RAPD) markers, generated by 14 random primers, were used to study the genetic variation among the populations. Elevation-dependent phenotypic variation was observed for a suite of metric traits. A scatterplot of mean values for these traits separated the populations from low, middle, and high altitudes into distinct groups. Cluster analysis using RAPD distance grouped the populations according to their altitudinal habitat, and a similar pattern of clustering was observed with respect to morphological distance also. The mean of both RAPD- and morphology-based pairwise genetic distance of populations belonging to similar altitudinal levels differed significantly. These estimates also depicted a significant decrease in genetic distance with increasing altitude. The results demonstrate that (i) effective isolation from gene flow coupled with natural selection governs genetic structure in O. malampuzhaensis and (ii) ecological heterogeneity associated with elevational gradient has a crucial role in the evolution of O. malampuzhaensis.Key words: Oryza malampuzhaensis, altitude, RAPD, morphological traits, genetic variations, molecular ecology.
Relative abundance and potential dispersal range of intersterility groups of Heterobasidion annosum in pure and mixed forests
Authors: Gonthier Paolo , Garbelotto Matteo , Varese Giovanna Cristina , Nicolotti Giovanni
Published: April 2011

In Europe the forest pathogen Heterobasidion annosum (Fr.) Bref. includes the S, P, and F intersterility groups (ISGs), each displaying a preferential specialization on Norway spruce (Picea abies (L.) Karst.), pine, and silver fir (Abies alba Mill.), respectively. In this paper, we present data about (i) H. annosum ISGs frequency in different forest types, (ii) the degree of host specificity of each ISG, (iii) the significance of the potential movement of airborne spores among forests, and (iv) the occurrence of SP chimeras in the northwestern Alps. Using woody spore traps, we sampled natural pure spruce and fir forests and a mixed spruce-fir forest. The ISG of 582 spores was determined by ISG-diagnostic taxon-specific competitive priming (TSCP) polymerase chain reaction (PCR) combined with PCR-mediated detection of ISG-specific introns in the ML5ML6 DNA region of the mitochondrial large ribosomal RNA (mt LrRNA). All three ISGs were found, and a strong correlation was observed between the F ISG and fir and the S ISG and spruce. In the mixed forest, no clear relationship between tree host species and host-specialized ISGs was found. In spite of a relative dominance of fir in the overstory of the mixed stand, the fir-associated F ISG represented only 11% of the total number of spores collected. This discrepancy was explained by the recent establishment of firs at this site. No SP nuclear-mitochondrial chimeras were found. This suggests limited gene flow between these ISGs.Key words: Heterobasidion annosum, host specificity, ISGs, gene flow, PCR, Alps.
Temporal variation in total leaf phenolics concentration of Quercus robur in forested and harvested stands in northwestern Spain
Authors: Covelo Felisa , Gallardo Antonio
Published: April 2011

Phenolic compounds show intraspecific variation and this may be important in resistance of plants to herbivory. Changes in total leaf phenolics concentration in young Quercus robur L. trees growing under pine canopies and those growing in recently tree harvested areas were studied for 3 years in northwestern Spain. The oaks from the felled areas had a greater leaf phenolics concentration than those under pine canopies and showed less variation between individuals from the population. The average leaf phenolics concentrations also varied significantly between study years. The variations during leaf development and growth are in accordance with the majority of hypotheses that explain investment in secondary metabolism compounds. Leaf phenolics concentrations decreased rapidly during leaf maturity and senescence, but this decrease depended on the time of leaf shedding, the concentration being substantially lower in the year when leaves had been attached longer to the tree. Variation of leaf phenolics concentration was greater in senescent leaves than in green leaves. Such high concentration variability represents a source of spatial and temporal heterogeneity not only for potential herbivores but also for the soil nitrogen cycle in terrestrial ecosystems.Key words: total phenolics, northwestern Spain, Quercus robur, Pinus pinaster, forest harvest, leaf senescence.
Growth and spore production of Plectosporium tabacinum
Authors: Zhang Wenming , Sulz Michelle , Bailey Karen L
Published: April 2011

Plectosporium tabacinum (van Beyma) M.E. Palm, W. Gams, et Nirenberg has been evaluated as a bioherbicide for the control of Galium spurium L. (false cleavers). Little is known, however, about the specific culture and sporulation requirements of this fungus on standard agar media. In addition, information on submerged liquid culture spore production is not available. This information is important for the successful culture and further development of this fungus as a biocontrol agent. This study characterized mycelial growth and sporulation of Plectosporium tabacinum on 14 different standard agar media over a range of light regimes, pH, and temperatures. Conditions required for submerged liquid culture spore production and resulting weed control efficacy were also assessed. This included the effect of liquid culture medium and pH and the effect of carbon source, nitrogen source, carbon concentration, and carbonnitrogen (C:N) ratio. Potato dextrose agar is the best agar medium for growth and spore production. On standard agar media, growth and spore production was not influenced by light regime. Medium pH did not affect mycelial growth and spore germination but the optimal pH for spore production was 7.0. The optimal temperature for the mycelial growth was between 22 and 25°C, but the optimal temperature for spore production was at either 20 or 30°C, depending upon the nutrient medium. Temperatures above 20°C were required to achieve greater than 90% spore germination. For submerged liquid culture spore production, Richard's solution (RS) is the best liquid medium for spore production. The optimal pH was 7.0 for RS but varied with culture media. Potassium nitrate and corn starch were the best nitrogen source and carbon source, respectively. A medium with a carbon concentration of 12.6 g/L and a C:N ratio of 7.5:1 is optimum for spore production and weed control efficacy.Key words: Plectosporium tabacinum, bioherbicide, mass production, fermentation, false cleavers, Galium spurium.
Variation in size and shape of Sphagnum hummocks in relation to climatic conditions in Hokkaido Island, northern Japan
Authors: Yabe Kazuo , Uemura Shigeru
Published: April 2011

Regional variation in size and shape of Sphagnum hummocks of eight lowland mires throughout Hokkaido Island, northern Japan, was examined in relation to climatic factors. The size and shape of hummocks significantly differed among the regions: low and flat hummocks occurred in the northern region and next to the Sea of Japan; moderately raised and conical hummocks occurred in the western part of the Pacific coast; and extremely raised and cylindrical hummocks occurred in the eastern region. Multiple regression analysis revealed that the mean and maximum heights and height/basal area of hummocks were negatively correlated with evapotranspiration rate (E0) in summer, duration of sunshine, and air temperature. Of these, evapotranspiration rate in summer positively correlated with radiation and thermal factors. Mean height of hummocks within a mire was increased with precipitation during the growing season. Because the regional difference of the hummock form was not related to the difference in nutrient conditions, the effects of evapotranspiration and precipitation prevailed over edaphic conditions. Higher E0 in summer was considered to cause water stress for hummock species in the northern region and next to the Sea of Japan, whereas heavy rainfall relieved it in the western region of the Pacific coast. Consequently, lower and flat hummocks were a result of the higher E0 in summer, moderately raised and conical hummocks of the medium E0 and high precipitation, and extremely raised and cylindrical hummocks of a lower E0 due to prolonged foggy days.Key words: evapotranspiration, duration of sunshine, minerotrophy, ombrotrophy, precipitation.
Ultrastructure of ascus and ascospore appendages of the mangrove fungus Halosarpheia ratnagiriensis (Halosphaeriales, Ascomycota)
Authors: Baker T A , Jones E BG , Moss S T
Published: April 2011

Halosarpheia Kohlm. et E. Kohlm is a genus of eighteen species, all of which have septate ascospores with unfurling polar appendages. Asci and ascospores of Halosarpheia ratnagiriensis Patil et Borse were examined at the scanning (including freeze-fracture) and transmission electron microscope levels. The ascus wall has two well-defined layers and the apical apparatus comprises a refractive, electron-dense, lens-shaped disk embedded within a less electron-dense thickening. The ascospore wall comprises an episporium and a bipartite mesosporium, and the appendages are formed by extrusion of mucilaginous material through an episporial pore field. Ascospore appendage ontogeny is compared with other genera with unfurling polar appendages: Cataractispora, Diluviocola, Tunicatispora, Tirispora, and Halosarpheia aquadulcis Hsieh, H.S. Chang et E.B.G. Jones and Halosarpheia heteroguttulata S.W. Wong, K.D. Hyde et E.B.G. Jones.Key Words: ascospore appendage ontogeny, marine ascomycetes, unfurling polar appendages, ultrastructure.
Biochemical assays for identifying seeds of lodgepole pine and other conifers fed on by Leptoglossus occidentalis Heidemann (Hemiptera: Coreidae)
Authors: Lait Cameron G , Bates Sarah L , Morrissette Karen K , Borden John H , Kermode Allison R
Published: April 2011

Radiography is a valuable tool for assessing quality of conifer seeds, but it cannot differentiate between aborted seeds and seeds that have been emptied by western conifer seed bug (Leptoglossus occidentalis Heidemann) feeding. We tested three biochemical marker-based assays that were developed to identify L. occidentalis damage to seeds of Douglas-fir, Pseudostuga menziesii (Mirb.) Franco, for their use in lodgepole pine, Pinus contorta var. latifolia Engelmann. The three assays included measurement of storage protein reserve depletion, immunodetection of fragments of insoluble (crystalloid) storage proteins, and immunodetection of L. occidentalis salivary proteins. Aborted seeds contained significantly less soluble and insoluble protein than seeds that were fed on by L. occidentalis. Polyclonal antibodies raised against 11S globulin crystalloid proteins or L. occidentalis salivary gland extracts only immunoreacted with proteins in seeds exposed to L. occidentalis feeding. In a single-blind test, antibody raised against salivary-gland extracts correctly distinguished between undamaged full seeds, unfilled aborted seeds, and seeds fed on by L. occidentalis. Immunodetection of L. occidentalis salivary proteins was also performed on seeds of Abies amabilis Dougl. ex J. Forbes, Tsuga heterophylla (Raf.) Sarg., Picea sitchensis Bong (Carr.), Pinus ponderosa Lawson, and Pinus monticola Dougl. ex D. Don. For all species, immunoreactive polypeptides were only detected in seeds fed on by L. occidentalis. These biochemical marker-based techniques could help researchers and seed orchard managers estimate seed losses caused by L. occidentalis in commercial seed orchards and natural forest stands.Key words: Leptoglossus occidentalis, saliva, biochemical markers, polyclonal antibody, immunodetection, Pinus contorta.
Fifty years of natural revegetation on a landslide in Franconia Notch, New Hampshire, U.S.A.
Authors: Francescato Valter , Scotton Michele , Zarin Daniel J , Innes James C , Bryant David M
Published: April 2011

We describe natural revegetation dynamics on landslides that occurred in 1948 and 1959 in Franconia Notch, New Hampshire, U.S.A. Analysis of aerial photographs from 1958, 1978, and 1996 indicate that the rate of revegetation of the landslide surface decreased over time, probably because of early saturation of easily colonized sites. In the 1948 landslide, we found that width and slope steepness within the landslide influenced the revegetation rate, while elevation did not. On the 1959 landslide, none of the tested factors were significantly correlated with vegetation recovery. Recolonization of narrow erosional zones tended to occur from the landslide edges inward; recolonization of wider erosional zones also occurred outward from islands of vegetation within the landslide. Floristic inventories were conducted in 1956 and 1996 using the point-centered quarter method and fixed plots of 1 m2 and were processed using cluster analysis, resulting in a grouping of the 1956 and 1996 plots into four and five clusters, respectively. The 1956 clusters consisted of exclusively herbaceous vegetation (zones with greater erosion) or prevalently shrub-arboreal vegetation, with Betula cordifolia Regel. dominant at high elevation and Betula papyrifera Marsh. and Betula alleghaniensis Britton dominant at low to middle elevation. The 1996 vegetation was characterized by prevalence of arboreal canopy made up of differing proportions of birch species, which varied with elevation.Key words: disturbance, floristic composition, regeneration, recolonization, succession, White Mountain National Forest.
Phylogenetic relationships of Polysiphonia (Rhodomelaceae, Rhodophyta) and its relatives based on anatomical and nuclear small-subunit rDNA sequence data
Authors: Choi Han-Gu , Kim Myung-Sook , Guiry Michael D , Saunders Gary W
Published: April 2011

The aim of this study was to reassess monophyly of the genus Polysiphonia and determine the phylogenetic affinities of its component lineages among related red algae belonging to the Rhodomelaceae. Our "total evidence" approach, combining 28 anatomical characters and small-subunit ribosomal DNA sequence data for 25 ceramialean algae including 14 species of Polysiphonia sensu lato (including two species of the recently described genus Neosiphonia) and nine related Rhodomelaceae, indicates that Polysiphonia sensu lato consists of three strongly supported clades, Polysiphonia group, Neosiphonia group, and a "multipericentral" group, and a single taxon lineage consisting of Womersleyella setacea. The type species of the genus, Polysiphonia urceolata (= Polysiphonia stricta) from the north Atlantic, formed a distinct clade with Polysiphonia morrowii and Polysiphonia pacifica from the northwest and northeast Pacific, respectively. The Neosiphonia group included Neosiphonia japonica and Neosiphonia savatieri from the northwest Pacific, as originally proposed, Polysiphonia harveyi from the north Atlantic, which shares diagnostic features with this genus, and the anomalous Polysiphonia elongata and Polysiphonia virgata from the north Atlantic and South Africa, respectively. Boergeseniella and Vertebrata from the north Atlantic and Enelittosiphonia from the northwest Pacific associated solidly with the multipericentral Polysiphonia fucoides and Polysiphonia nigra from the north Atlantic. The implications for the taxonomy of Polysiphonia sensu lato and related genera within the Rhodomelaceae are discussed.Key words: Neosiphonia, nuclear small-subunit rDNA, phylogeny, Polysiphonia, Rhodomelaceae, Rhodophyta, systematics.
Electron microscopic study of oospore maturation and germination in an emasculate isolate of Saprolegnia ferax. 2. Wall differentiation
Authors: Beakes Gordon W.
Published: April 2011

The fine structure of oogonium and oospore walls of Saprolegnia ferax and the changes associated with germination are described. Mature oogonium walls have well defined primary and secondary layers with pits arising as the result of the localized absence of secondary wall deposition. The mature oospore wall has a 0.1 μm thick outer wall separated from a 2.0 μm thick inner wall by a thin (40 nm) electron-dense, multilaminate layer. Within the inner wall is an optically dense (0.5 μm) inner zone composed of particulate and membranous material. At the onset of germination most of the microfibrillar inner wall is digested and reabsorbed and a new germination wall is secreted around the protoplast. As the spores swell the vestigial oospore remnants either rupture or disintegrate and germ tubes develop by the outgrowth of the germination wall. Elaborate plasmalemmasome complexes appear during the period of spore swelling and the mature germling walls become thickened and contain abundant lomasomes and peglike ingrowths. Oospore wall morphogenesis in Saprolegnia is compared with that in other oomycetes and discussed in relation to the possible mechanisms of dormancy.
Glutaraldehyde-induced deposition of callose
Authors: Hughes J. E. , Gunning B. E. S.
Published: April 2011

Aldehyde fixation of Abutilon nectaries induces deposition of callose, probably at plasmodes-mata. The phenomenon was analysed by examining a range of other tissues, several of which show a similar response, and by varying the fixation conditions. Callose deposition occurs within 15 min of the onset of fixation in immature nectaries, and does not occur in mature nectaries. Low temperature controls show that the deposition is artefactual and that it may give an erroneous view of the structure of plasmodesmata.
Activation du renouvellement pariétal et membranaire de cellules radiculaires de courge, soumises à l'agression d'une bactérie, l’Erwinia carotovora, agent infectieux de la pourriture molle (soft rot)
Authors: Vogt Gabrielle-Françoise
Published: April 2011

Root cells of young pumpkins (Cucurbita pepo L.), infected by a 30-min exposure to a phytopathogenic bacterium, Erwinia carotovora (Jones) Holland, show an activation of the cell wall polysaccharides' renovation. The processes of exocytosis and endocytosis which take place lead to a plasmic renovation. Hypotheses concerning certain moments of this turnover and its possible phytopathologic consequences may constitute the basis of future research.
Effects of 11 fungicides on endomycorrhizal development in sour orange
Authors: Nemec S.
Published: April 2011

Eleven fungicides were examined in five tests for their effects on endomycorrhizal development in sour orange seedlings. Copper, metalaxyl, thiabendazole, captan, captafol, chloroneb, and formaldehyde were tested for their effects on Glomus etunicatus, and chlorothalonil, sodium azide, benomyl, and maneb were tested for their effects on G. mosseae. Captafol, chloroneb, metalaxyl, and captan did not adversely affect growth of mycorrhizal plants, although some adverse effect on the fungus was apparent with all rates of captafol and the high rate of captan. All rates of benomyl and thiabendazole reduced plant growth, and mycorrhizal infection and sporulation decreased as rates of thiabendazole increased. Plant growth was better and fungus sporulation higher than that of the mycorrhizal control in all sodium azide treatments. Copper at rates of 112 and 224 kg/ha significantly depressed plant growth but not infection and fungus sporulation. Maneb and chlorothalonil, which had no effect on G. mosseae at the low rate of 5.6 kg/ha, sharply reduced fungus sporulation and mycorrhizal plant growth at 11.2 and 22.4 kg/ha. Formaldehyde at three rates was toxic to G. etunicatus.
Growth of plant cell suspension cultures on glycerol as a sole source of carbon and energy
Authors: Jones A. , Veliky I. A.
Published: April 2011

Suspension cultures of Daucus carota Ca68, Cannabis sativa 95C, and Ipomoea sp. were screened for their ability to utilize an alternate to sucrose as a carbon source for growth. Of the substrates tested glycerol was chosen for further study and all three cultures were adapted to growth on this carbon source added in lieu of sucrose to 71V medium. Growth of C. sativa 95C proceeded only after a long lag phase. The latter could be reduced by replacing the ammonia nitrogen with nitrate nitrogen or almost eliminated by controlling the pH of the medium at either pH 5.1 or pH 6.3. In contrast, cultures of D. carota Ca68 and Ipomoea sp. grew on glycerol after a short lag of 1–2 days.The utilization of glycerol as a carbon source by plant cell cultures is discussed with respect to other reports using this and other substrates as alternatives to sucrose. The influence of ammonia on the initiation of growth, nitrate utilization, and the initial pH of the medium is discussed in view of our findings.
Induction and differentiation of haploid Triticum aestivum cv. Chinese Spring callus initiated from haploid embryos
Authors: Pental Deepak , Gunckel J. E.
Published: April 2011

Haploid embryos were produced by Triticum aestivum × Hordeum bulbosum crosses. Approximately 4300 florets of T. aestivum cv. Chinese Spring were emasculated and pollinated with pollen of diploid and tetraploid H. bulbosum. Haploid seeds started aborting 8–10 days after pollination and at this stage embryos were excised. Total haploid embryo set was only 0.2%.Callus was induced from the haploid embryos and root apices excised from the haploid plants on T medium + 1 mg/L 2,4,5-trichlorophenoxyacetic acid. These calli were subcultured once and then put on differentiation media: T medium and T medium with indole-3-acetic acid (IAA), naphthaleneacetic acid (NAA), IAA + 6-furfurylaminopurine (kinetin, K), or NAA + K. Histologically, calli growing on auxin medium were heterogeneous with peripheral meristematic loci embedded in a parenchymatous mass of cells. On differentiation media calli produced copious roots from the meristematic loci. One callus on control medium (T only) gave rise to an isolated shoot. The chromosome number of differentiated roots was always 2n = 3 = 21.
Cytoplasmic streaming and transport in the characean alga Nitella
Authors: Allen N. Strömgren
Published: April 2011

Plasmodesmata were recorded in vivo in Nitella furcata using polarization and differential interference-contrast light microscopy, techniques that could prove useful for further physiological experimentation on intercellular transport in characean cells.Freeze-fractured, deep-etch replicas of Nitella endoplasm were prepared without the use of cryoprotective agents. The endoplasm, in which rapid cytoplasmic streaming occurs, contains intricate three-dimensional networks of filaments of which two prominent size classes are characterized: 7- to 8-nm putative actin filaments and 4- to 5-nm putative myosin filaments. It is quite likely that the putative actin filaments are components of the endoplasmic filaments, and that these filaments interacting with the 4- to 5-nm filaments produce the motive force generating the observed cytoplasmic streaming.
Microfilaments in plant vascular cells
Authors: Parthasarathy M. V. , Pesacreta T. C.
Published: April 2011

Microfilaments 50–70 Å (Å = 0.1 nm) in diameter are commonly found in vascular tissue of elongating roots and stems of many plants. Such microfilaments occur in bundles in peripheral regions of elongating or differentiating vascular cells, and are usually oriented parallel to the longitudinal axis of the cells. Although the longest microfilament bundle we have measured is about 15 μm, we suspect that the bundles are at least as long as the cells that contain them. The bundles are 0.1–0.4 μm in width and are often in apparent contact with organelles, but there is no definite indication of their being anchored to plasmalemma or any organelle. The microfilaments are comparable in size and morphology to actin filaments. The distribution of microfilament bundles in the vascular tissue of various plants and the possible function of the bundles is discussed.