bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of simple sugars, salts, andBotrytis-specific monoclonal antibodies on the binding of bacteria and yeast to germlings ofBotrytis cinerea
Authors: Cook D WM , Dewey F M , Long P G , Benhamou N
Published: April 2011

The influence of simple sugars, salts, and Botrytis-specific monoclonal antibodies on the binding of three bacteria (Enterobacter aerogenes Hormaeche & Edwards, Enterobacter cloacae (Jordan) Hormaeche & Edwards, and Ochrobactrum anthropii gen.nov.) and three yeasts (Candida sake (Sarto & Ota) van Uden & Buckley, Candida pulcherrima (Lindner) Windisch, and Trichosporon pullulans (Lindner) Diddens & Lodder) to Botrytis cinerea (Persoon:Fr) was examined. Solutions of 0.1 M D(+)-galactose, L-fucose, or Botrytis-specific monoclonal antibodies significantly reduced populations of E. aerogenes and E. cloacae adhering to pathogen germlings, whereas 0.1 M raffinose significantly reduced C. sake or C. pulcherrima adhesion. In cytochemical studies, lectin-gold labeling demonstrated the presence of galactose moieties in the walls or matrix of E. aerogenes, and this labeling was diminished in bacteria that were attached to B. cinerea. Immunolabeling with a Botrytis-specific monoclonal antibody that recognizes a glycoprotein was particularly intense in condensed regions of the pathogen matrix associated with adherent E. aerogenes, whereas C. sake - B. cinerea interactions revealed a loose encapsulation of adherent yeast cells by the matrix of B. cinerea. Results from this study suggest the presence of several adhesion mechanisms that can be distinguished according to yeast or bacterial binding and further defined according to the genus.Key words: adhesion, bacteria, biocontrol, Botrytis cinerea, ultrastructure, yeast.
Contrasting seed morphology dynamics in relation to the alleviation of dormancy with soil storage
Authors: Tieu Anle , Egerton-Warburton Louise M
Published: April 2011

We examined the effect of prolonged (up to 450 days) soil burial in the field on seed morphological traits (seed coat structure, permeability) to identify their potential roles in seed dormancy and release. Such traits were examined in species with seeds that demonstrated an obligate requirement for soil storage before germination: the dormant seeds of Anigozanthos manglesii D. Don, Conostylis neocymosa Hopper, Stylidium affine Sonder, and Stylidium crossocephalum F. Muell., and the deeply dormant fruits of Leucopogon conostephioides D.C. We detected species-specific and environmentally induced variation in seed morphology following soil burial. In A. manglesii and L. conostephioides, a significant deterioration of the seed coat or fruit wall and an increased permeability of the seed coat to water and solutes were correlated with germination responses. In these species, the seed coat and (or) fruit wall delayed germination until (morpho) physiological dormancy was broken. In C. neocymosa, S. affine, and S. crossocephalum, weathering of the seed coat, permeability, and germination were not correlated traits. These species appeared to possess physiological dormancy mechanisms and required environmental cues for dormancy release.Key words: physiological dormancy, soil burial, seed coat, morphology.
Infection of Douglas-fir by Leptographium wageneri
Authors: Hessburg Paul F , Hansen Everett M
Published: April 2011

In three related experiments, root systems of 2-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were dip-inoculated with a viscous blend of Leptographium wageneri var. pseudotsugae Harrington and Cobb spores and hyphal fragments and planted in a sterile potting medium. Infection frequency and points of entry were evaluated for dormant seedlings and seedlings that had been active for 4 and 8 weeks. All putative black stain infections and other areas of sapwood discoloration were free-hand sectioned and examined with a bright-field microscope and phase-contrast optics. This technique was shown to be 100% reliable in a prior experiment with 223 inoculated Douglas-fir seedlings that paired microscope examinations with pathogen isolation. In this study, all lesions were sectioned and examined at 250-1000 diameters magnification for the presence of L. wageneri var. pseudotsugae hyphae and characteristic pathological anatomy. Complete root system dissections revealed that L. wageneri var. pseudotsugae infected roots through wounds and natural openings where a direct path to the xylem was exposed and never penetrated living cortical or cambial tissues to infect its host. Among the dormant inoculated seedlings, 63% of infections occurred through wounds associated with nursery handling. Wound infection frequency decreased to zero in seedlings inoculated 8 weeks after coming out of dormancy. Seedlings inoculated 4 and 8 weeks after coming out of dormancy were most frequently infected through openings occurring at sites of new lateral root initiation. Infection of dead fine root stubs suggested that during periods of increased fine root mortality, these sites may be important for the new infection of healthy trees and egress from already diseased trees.Key words: Black-stain root disease, Leptographium wageneri, Verticicladiella wagnerii, infection courts, wounding, vascular wilt.
Antennulariella batistae n.sp. and its Capnodendron and Antennariella synanamorphs, with notes on Capnodium capsuliferum
Authors: Hughes S J
Published: April 2011

An illustrated account is presented of the perithecia and two synanamorphs of the sooty mould Antennulariella batistae n.sp. Perithecia bear hyphoid appendages, asci are fissitunicate, and ascospores are hyaline and 1-septate. The hyphomycetous synanamorph Capnodendron trichomericola, type of this genus, is variable, with conidiophores and phragmoconidia usually shorter on the host but inordinately longer in agar cultures. Meristogenous, intercalary or terminal pycnidia of the Antennariella bahiensis synanamorph produce minute hyaline, ellipsoidal conidia. Studies of isotypes of Capnodium capsuliferum indicate that this epithet cannot be used for the new species of Antennulariella. A brief history of Capnodium capsuliferum and its nomenclatural variants is provided, indicating its relevance to the status of Antennella, Capnocrinum, Capnodina, and "Capnodenia."Key words: sooty moulds, Antennulariella, Capnodendron, Antennariella.
Initial events in the colonisation of tomatoes by Oidium lycopersici, a distinct powdery mildew fungus of Lycopersicon species
Authors: Jones Hannah E , Whipps John M , Thomas Barry J , Carver Tim LW , Gurr Sarah J
Published: April 2011

The rDNA intergenic spacer sequence of Oidium lycopersici (ana.; Cooke & Massee 1888, emend. Noordeloos and Loerakker 1989, emend. Mieslerova and Lebeda 1999) was determined and compared with the sequences of other powdery mildews. This pathogen was shown to be distinct from other powdery mildew fungi found on tomato, but it exhibited a close similarity to Erysiphe aquilegiae var. ranunculi. The initial events involved in the germination of conidia and subsequent formation of the appressorium in the newly described powdery mildew of tomato, O. lycopersici, were studied by light and scanning electron microscopy. Scanning electron microscopy revealed the conidial coat to be smooth to slightly rugose and the appressoria to be multilobed and attached to the host by a mucilaginous pad of extracellular material.Key words: Oidium lycopersici, tomato powdery mildew, ITS, life cycle, light microscopy, electron microscopy.
Inbreeding depression and floral type fitness differences inViola canadensis(Violaceae), a species with chasmogamous and cleistogamous flowers
Authors: Culley Theresa M
Published: April 2011

Few studies of inbreeding depression have focused on species producing both showy, chasmogamous (CH) flowers and self-pollinated, cleistogamous (CL) flowers. The goals of this investigation were to measure the level of inbreeding depression in the North American violet, Viola canadensis L., and to determine if any fitness differences were linked to floral type (CH versus CL) rather than to cross type (self versus outcross). Hand pollinations were carried out to produce self- and outcross-pollinated CH progeny, and CL seeds were also collected. In a greenhouse, selfed and outcrossed CH flowers produced similar numbers of seeds, and both types of progeny had similar survival rates and comparable numbers of CH flowers, although outcrossed CH progeny had 14% greater vegetative biomass than selfed CH progeny. The level of inbreeding depression in V. canadensis was low, indicating that there may be few drawbacks to selfing in this species. A comparison of CL and self-pollinated CH progeny showed that, although there were differences in CH flower number, overall fitness differences were minimal. The similar performance of selfed (CL and CH) and outcrossed progeny in early life-history stages of V. canadensis suggests a history of inbreeding in the population.Key words: cleistogamy, inbreeding depression, outcrossing, selfing, Viola canadensis.
Nectria and Fusarium. II. Cosmospora zealandica comb.nov. and its anamorph, Fusarium zealandicum sp.nov.
Authors: Nirenberg Helgard I , Samuels Gary J
Published: April 2011

Nectria zealandica Cooke is transferred to the genus Cosmospora. This species is redescribed and its anamorph, Fusarium zealandicum sp.nov., is described as new and both are illustrated. The systematic position of Cosmospora zealandica comb.nov. and its anamorph is discussed.Key words: Hypocreales, Nectriaceae, taxonomy, New Zealand.
Flower orientation in Pachycereus pringlei
Authors: Tinoco-Ojanguren Clara , Molina-Freaner Francisco
Published: April 2011

The orientation of flowers in columnar cacti has been a subject of great interest to plant biologists. The interpretation of this pattern has invoked warmer temperatures as the underlying factor. In this paper, we describe flower orientation in two populations of Pachycereus pringlei (S. Watson) Britton & Rose and propose a hypothesis of the underlying mechanism. Stems from the two populations showed a significant mean direction of their flowers, with most flowers (70-77%) present between 90 and 270°. Photosynthetic photon flux density interception and stem temperature reached maximum values on south-facing ribs, showing concordance with flower orientation. We suggest that PFD interception, through its influence on CO2 uptake and stem temperature, is the major factor underlying the observed orientation of flowers in P. pringlei.Key words: columnar cacti, flower orientation, Pachycereus pringlei, PFD interception.
Recolonization of bigleaf maple branches by epiphytic bryophytes following experimental disturbance
Authors: Cobb Alexander R , Nadkarni Nalini M , Ramsey Grant A , Svoboda Abraham J
Published: April 2011

The dynamics of epiphytic bryophyte communities following natural and human disturbance have rarely been quantified. We describe the response of bryophyte communities on bigleaf maple trees (Acer macrophyllum Pursh) in Olympia, Washington, following their experimental removal. Approximately 8% of the exposed area was recolonized by bryophytes 1 year after clearing, and 27% after 3 years. Lateral encroachment from bryophytes on the sides of the 20-cm-long plots accounted for 75% of this recolonization, with growth from residual plant parts or aerially dispersed diaspores accounting for the remaining 25%. Though it was not possible to distinguish between the latter two sources of cover, the number of clear de novo colonization events over the course of the year was low (0.18 dm-2). Disturbance appeared to reduce bryophyte diversity at this successional stage, as alpha and gamma diversity remained low after 1 year and had not recovered after 3 years. Reflecting the preponderance of lateral encroachment as the mechanism for recolonization, disturbance size may significantly affect the time needed to recolonize disturbed branch substrates. In addition to contributing to ecologists' understanding of processes of succession, these experiments may help to develop sustainable practices for moss-harvesting in the Pacific Northwest.Key words: succession, bryophytes, epiphytes, Acer macrophyllum, recolonization, canopy studies.
A morphological phylogenetic analysis ofAesculusL. andBilliaPeyr. (Sapindaceae)
Authors: Forest Félix , Drouin Josée Nadia , Charest René , Brouillet Luc , Bruneau Anne
Published: April 2011

The hippocastanaceous Sapindaceae (family Hippocastanaceae) consists of two genera: Aesculus and Billia. The genus Aesculus (buckeyes) is distributed throughout the northern hemisphere. Twelve of the thirteen species of Aesculus are found in eastern Asia and North America, and one is native to Europe. The two species of the genus Billia are found in South and Central America. Aesculus is traditionally divided into five sections. This analysis, based on morphological characters, suggests that the monotypic section Parryanae (Aesculus parryi Gray) is sister to the remainder of the genus, and the other species are divided into two clades. One clade comprises all species from southeastern North America with the monotypic section Macrothyrsus (Aesculus parviflora Walt.) as sister to section Pavia. The other clade consists of all species found in Eurasia included in sections Aesculus and Calothyrsus, with the only North American member of this clade (Aesculus californica (Spach) Nutall) as sister to the rest of the group. According to this analysis, section Calothyrsus is rendered paraphyletic by the inclusion of section Aesculus. In contrast to previous studies that suggest an Asian origin for the genus, our study suggests an American origin for Aesculus from an ancestor similar to Billia with a single migration to Eurasia via the Bering land bridge.Key words: Aesculus, Billia, character evolution, Hippocastanaceae, morphology, phylogeny, Sapindaceae.
Low ectomycorrhizal inoculum potential and diversity from soils in and near ancient forests of bristlecone pine (Pinus longaeva)
Authors: Bidartondo M I , Baar J , Bruns T D
Published: April 2011

Intersite variation in ectomycorrhizal (ECM) inoculum potential in soils from 16 sites located in arid subalpine areas of the White Mountains of California was quantified. The study sites included valleys dominated by big sagebrush (Artemisia tridentata Nutt.) and mountainsides dominated by ancient Great Basin bristlecone pine (Pinus longaeva Bailey). ECM inoculum potential was not detected at three of four valley sites nor in 42% of forest soil samples. Only 10 mycorrhizal species were detected in bioassays, and four of those accounted for 94.5% of all colonized seedlings, in order of decreasing abundance these were Pyronemataceae sp., Rhizopogon sp., Wilcoxina rehmii Yang & Korf, and Cenococcum sp. These species were identified also from in situ mycorrhizal roots. The abundance of the dominant Pyronemataceae sp. was significantly positively correlated with pH, which at all forest sites was high compared with typical conifer forest soils. Our results show that the ECM inoculum potential of soils is low, homogeneous, and spatially restricted in these ancient high-elevation forests.Key words: fungal community, molecular ecology, spore dispersal.
Tri-iodobenzoic acid affects shoot apical meristem formation and function in zygotic embryos ofBrassica napuscv. Topas
Authors: Ramesar-Fortner Nicole S , Yeung Edward C
Published: April 2011

The effect of an auxin transport inhibitor, tri-iodobenzoic acid, on the formation and subsequent function of the shoot apical meristem in zygotic embryos of Brassica napus L. was examined. Globular and heart stage embryos were cultured in the presence of tri-iodobenzoic acid. Only embryos at the globular stage of embryogenesis were affected by tri-iodobenzoic acid. Upon treatment, the embryos did not develop two separate cotyledons and, therefore, did not attain bilateral symmetry. Furthermore, the shoot apical meristem of these embryos was altered, as a characteristic tunica-corpus organization was not observed. The cells of the surface layer continued to maintain their meristematic characteristics and divided mainly in the anticlinal direction. The subapical cells differentiated into parenchyma cells and continued to expand such that a corpus organization never developed. Therefore, by the end of the culture period, the shoot apical meristem appeared very broad and shallow. Treated embryos that were transferred to a conversion medium exhibited a dramatic decline and delay in the formation of leaves compared with untreated embryos. Histological observations revealed that the shoot apical meristem continued to expand in width. A low percentage of treated embryos were able to convert; however, leaves were produced from a new shoot meristem that developed in the axillary position. No morphological or histological changes were evident when the embryos were treated later, at the heart stage of embryogenesis.Key words: auxin, Brassica napus, embryo, shoot apical meristem, tri-iodobenzoic acid.
Dynamics and morphology of giant circular patterns of low tree density in black spruce stands in northern Quebec
Authors: Giroux Jean-François , Bergeron Yves , Veillette Jean J
Published: April 2011

Giant circular patterns of low tree density in black spruce (Picea mariana) stands were investigated in the Abitibi region of Quebec. We used dendrochronological techniques to test the hypotheses that ring patterns of low tree density are caused either by radial changes in spruce mortality or productivity. Seven circles were sampled. We found no gradient in the age of spruce along circle radii suggesting that rings of low tree density do not expand radially, that is, they are not spatially dynamic entities. The results indicate, however, that spruce trees were less dense and productive within the rings due to excessive moisture in the soil. Measurements of surface elevation, thickness of the organic layer and elevation of the mineral substrate across the circles revealed that a depression in the mineral soil beneath the rings traps the surface water and this area of poor drainage seems to prevent the establishment of black spruce within the rings. The origin of the ring-shaped depressions was attributed to geological or geomorphological causes.Key words: black spruce, Picea mariana, mortality, productivity, rings, geomorphology.
Canopy microclimate and arboreal lichen loading in subalpine spruce-fir forest
Authors: Campbell Jocelyn , Coxson Darwyn S
Published: April 2011

Hair lichen communities in Engelmann spruce (Picea engelmannii)  subalpine fir (Abies lasiocarpa) forests of the northern Cariboo Mountains (British Columbia) show distinct vertical zonation. Alectoria sarmentosa reaches peak abundance in the lower canopy (over 35 kg/ha) whereas Bryoria spp. lichens reach peak abundance in the upper canopy (over 250 kg/ha). These distribution patterns are accentuated by stand structure with trees growing in clumps retaining significantly higher lichen loading on a per branch basis compared to solitary trees. The vertical zonation of lichen communities is accompanied by distinct trends in canopy microclimate. Snowmelt events account for the largest proportion of observed thallus hydration in both Alectoria and Bryoria. Although canopy microclimate is surprisingly isothermal during rainfall events, the attenuation of thallus hydration after wetting is typically greater for lower canopy exposures. An important exception to this pattern is seen under midwinter conditions, when solar insolation is insufficient to sustain prolonged lower canopy snowmelt. Our data support the hypothesis that ventilation in upper canopy exposures is a contributing factor in the vertical zonation of Alectoria and Bryoria communities. Upper canopy Bryoria rely more heavily on snowmelt events to sustain thallus hydration, whereas lower canopy Alectoria utilize summer rainfall events to a greater extent. We hypothesize that physiological mechanisms, through which these patterns of canopy microclimate influence lichen zonation, may include an intolerance to prolonged wetting by Bryoria and higher resaturation respiration costs in Alectoria, which would limit it to more mesic canopy exposures. We believe that the observed distribution of canopy lichens ultimately reflects the long-term interaction of both physiological and successional processes (lichen colonization and dispersal) within the canopy.Key words: canopy, epiphytes, lichens, microclimate.
Subnivean embryo development in the alpine herb Caltha leptosepala (Ranunculaceae)
Authors: Forbis Tara A , Diggle Pamela K
Published: April 2011

Caltha leptosepala D.C. (Ranunculaceae) is a perennial herb of alpine wet meadows. Seeds of this species have morphophysiological dormancy; they contain a rudimentary embryo that must undergo further development prior to germination. The embryo itself is also dormant and requires a physiological cue for resumption of development. We ask how C. leptosepala can break embryo dormancy and complete embryo development, germination, and seedling growth under the constraint of the extremely short alpine wet meadow growing season. Seeds were stratified at 2.5°C and collected at regular intervals for germination trials and histological analysis. At dispersal, the embryo occupies approximately 7% of the length of the seed and is dormant. Embryo development resumes within 1 month of stratification. Embryos grow to fill the seed over a 4- to 7-month period. Germination rates are positively correlated with stratification time and reach 50% at 4 months and 70% at 7 months. Because embryo development requires a time period longer than the snow-free period prior to germination in the alpine wet meadow, we conclude that embryo development in C. leptosepala takes place beneath alpine snowbanks. Morphophysiological dormancy in Caltha is not uniquely derived, but the ability of Caltha embryos to develop and germinate at low temperatures may be an adaptation to their environment.Key words: alpine, rudimentary embryo, Ranunculaceae, seed, dormancy, germination.
Changes in actin microfilament arrays in developing pea root nodule cells
Authors: Davidson A L , Newcomb W
Published: April 2011

Various microorganisms that form symbiotic associations with plant roots alter the cytoskeleton of host cells. The objective of this study was to determine the organization of actin microfilaments in developing Pisum sativum L. (pea) root nodule cells at various stages after infection by Rhizobium leguminosarum bv. viciae. Fluorescently labelled microfilaments in uninfected pea root nodule cells occur in association with the nucleus, along cytoplasmic strands, and as long microfilament bundles randomly organized in the cortex of the cell. These actin arrays are also present in recently infected cells that have been invaded by an infection thread and contain a small number of bacteroids. In addition, the recently infected cells contain diffuse cytoplasmic actin, long actin microfilament bundles near the vacuole, and a nuclear-associated network of microfilament bundles. In older infected cells, the predominant array is a network of cytoplasmic microfilaments that are wavy and extend in multiple directions within the cell; the network is equally abundant in all regions of the cytoplasm and may interact with the bacteroids and organelles. Thus, actin microfilaments reorganize during the pea root nodule infection process to form distinct arrays whose organization depends on the stage of infection.Key words: nodule, actin microfilaments, Rhizobium, pea, symbiosis.
Colonization and invasion of peanut (Arachis hypogaea L.) roots by gusA-marked Bradyrhizobium sp.
Authors: Uheda Eiji , Daimon Hiroyuki , Yoshizako Fumiki
Published: April 2011

Tufted rosettes of long root hairs occur in axils of young lateral roots of peanut (Arachis hypogaea L.). Analyses of serial sections of the axils of emerging lateral roots revealed multiple layers of root hair cells. The cells of the outer layer partially overlie the adjacent cells of the inner layer. When Bradyrhizobium cells with an integrated gusA gene were inoculated onto peanut roots and the roots subsequently stained with X-gluc, blue spots indicating the presence of colonies of Bradyrhizobium were observed in the axils of lateral roots. Blue spots were also observed in other areas on the root surface. Transmission electron microscopy revealed that the primary wall of the base of root hair cells has a loose construction. Upon inoculation of Bradyrhizobium, bacteria entered only between root hair cells through the middle lamella. In other areas of the root surface other than axils of lateral roots, the cells had modified walls similar to those at the base of root hair cells. However, invasion by Bradyrhizobium of the cell wall was not observed.Key words: Arachis hypogaea, gusA-marked Bradyrhizobium, cell wall, invasion, root hair cell, root nodules.
Molecular characterization and regulation of formate dehydrogenase inArabidopsis thaliana
Authors: Li Rong , Bonham-Smith Peta C , King John
Published: April 2011

In a previous publication we reported the purification of formate dehydrogenase (FDH, EC 1.2.1.2.) from Arabidopsis thaliana (L.) Heyn. and some of its properties. Here we report the identification of an Arabidopsis FDH cDNA, as well as studies of the molecular characterization and regulation of the enzyme in Arabidopsis. FDH is present as a single-copy gene in the Arabidopsis genome and is located on chromosome V. The deduced amino acid sequence of the Arabidopsis enzyme shows over 80% identity with those from other plants (potato, barley, rice). Northern and western blots show that the FDH mRNA and protein levels in Arabidopsis leaves are similar to those in flowers and stems and higher than those in roots. The effects of chemical and environmental factors on FDH expression in leaves were investigated and compared with their effects on formaldehyde dehydrogenase (FADH, EC 1.2.1.1.). Induction of FDH by one-carbon metabolites, such as methanol, formaldehyde, and formate, was observed at the protein level, but changes at the transcript level were small and different from those observed for FADH. While the steady-state levels of FDH transcripts increased quickly (within hours) and strongly in response to various stresses, protein amounts increased slowly, after 1 to 3 days; FADH transcripts showed no observable change. The possible mechanism of regulation of FDH at both the transcript and protein levels is discussed.Key words: Arabidopsis, formate dehydrogenase, formate metabolism, one-carbon metabolites, stress.
Landscape genetic structure ofPinus banksiana: allozyme variation
Authors: Saenz-Romero Cuauhtemoc , Guries Raymond P , Monk Andrew I
Published: April 2011

Many of Wisconsin's jack pine forests originated following fire or agricultural abandonment creating a forest mosaic fragmented by a history of disturbance and past land use. The extent and patterning of genetic diversity at a landscape scale (30 × 30 km) was investigated in 82 natural Pinus banksiana Lamb. (jack pine) stands in Wisconsin using 14 polymorphic allozymes. Most measures of genetic diversity and overall allelic frequencies varied little among these stands, and Reynolds' (coancestry) genetic distances were small (mean = 0.026). Genetic differentiation among stands was limited but significant ([Formula: see text]ST= 0.022). Gene flow (Nm) is extensive, estimated to be slightly more than 11 migrants per generation. Autocorrelation analysis provided evidence for a weak pattern of genetic structure at a few loci with a spatial scale of 815 km. However, when all loci were examined together the populations did not present a clear spatial pattern across the landscape, probably because of extensive gene flow among stands.Key words: jack pine, allozymes, genetic diversity, population differentiation, spatial autocorrelation, gene flow.
The North American ginseng inflorescence: development, floret abscission zone, and the effect of ethylene
Authors: Fiebig Andrea E , Proctor John TA , Posluszny Usher , Murr Dennis P
Published: April 2011

Characterization of the North American ginseng (Panax quinquefolius L.) inflorescence, the floret abscission zone, and its stimulation by ethylene were undertaken to gain insights into the potential for floret abscission induction as a replacement for the industry practice of expensive manual removal of the inflorescence. In each of 3 years, peduncle length of 3-year-old cultivated ginseng inflorescences increased rapidly in June, reaching maximal values of 140180 mm. During this period, seed head diameter also increased to about 35 mm, while seed head fresh mass increased in July and August to 6.58.0 g. Flowering in 1996 and 1997 began in the last 2 weeks of June and lasted through July, with open flowers never exceeding 35%. Anatomical studies and manual dissection of 1- and 3-year-old perennating buds revealed development of the floral primordia first at their periphery and progressing centripetally. Stamen initials were seen as a pentamerous whorl just under the petal primordia, and the characteristic inferior ovary initiated as a slight depression at the centre of the floral meristem. Sections through 3-year-old inflorescences harvested on May 23, 1996, showed that distal floral apices had already formed constriction zones between the flower and the pedicel, indicating the position of the abscission zone. Length of time to ethylene-induced abscission zone formation was less than 24 h in 3-year-old ginseng harvested on July 23, 1997. The abscission threshold for ginseng berry drop was in the range of 10-100 µL·L1 ethylene.Key words: anatomy, flowering, Panax quinquefolius, perennating bud.
Lollipopaia minuta from Thailand, a new genus and species of the Diaporthales (Ascomycetes, Fungi) based on morphological and molecular data
Authors: Inderbitzin Patrik , Berbee Mary L
Published: April 2011

In this paper, we describe the new genus and species Lollipopaia minuta from a tropical rain forest in Thailand. The ascomata were long beaked and seated on a pseudoparenchymatous stroma that was erumpent through the bark of a decaying branch. Mature ascomata were readily formed under laboratory conditions. Lollipopaia minuta had ascomatal walls forming a textura intricata in surface view and deliquescent paraphyses. The asci floated freely at maturity and had a nonstaining apical ring. These characters are found in the Diaporthales. However, the habit of the stroma combined with the filiform ascospores distinguished L. minuta from all known genera of the Diaporthales. Thus, a close relationship to taxa outside the Diaporthales was considered. Lollipopaia minuta was similar to Ophioceras or Pseudohalonectria in shape of the ascomata, asci, and ascospores. However, phylogenetic analyses based on small subunit ribosomal DNA sequences confirmed the placement of L. minuta within the Diaporthales with 100% bootstrap support. A closest relative within the Diaporthales was not determined.Key words: Magnaporthaceae, microfungi, taxonomy, tropical mycology.
Ramet spacing of Elymus lanceolatus (thickspike wheatgrass) in response to neighbour density
Authors: Humphrey L David , Pyke David A
Published: April 2011

Many plants exploit patchy resources through clonal foraging. Plants established in field plots were used to determine if Elymus lanceolatus ssp. lanceolatus (Scribner et J.G. Smith) Gould (thickspike wheatgrass) showed a clonal foraging response to neighbour densities, as it had previously shown to patchy soil nutrients. Neighbours consisted of the rhizomatous E. lanceolatus ssp. lanceolatus and the bunchgrass Elymus lanceolatus ssp. wawawaiensis (Scribner et Gould) J.R. Carlson et D.R. Dewey (proposed name), which are both native to the semiarid western U.S.A., and their ratios as well as total densities varied. Rather than an increase in spacing of exploratory ramets at high densities, as expected with clonal foraging, there was a decrease in spacing in both years of the experiment. Fewer target plants produced exploratory ramets at higher densities only in the second year. These reductions in exploratory clonal growth at higher neighbour densities, which were opposite to E. lanceolatus ssp. lanceolatus' response to low-resource patches, occurred perhaps because soil resource levels were too low overall to support rhizome production, and this condition was more pronounced in the second year. Physical resistance from neighbour roots perhaps also reduced rhizome production. However, rhizome growth may not be beneficial in such cases, and plants may be adapted to produce exploratory rhizomes only when some high-resource patches are encountered by the clone.Key words: clonal growth, competition, Elymus lanceolatus, plasticity, resource levels, rhizomes.
Allozyme diversity of two endemicPetrocoptisspecies:P. montsiccianaand its close relativeP. pardoi(Caryophyllaceae)
Authors: López-Pujol Jordi , Bosch Maria , Simon Joan , Blanché Cèsar
Published: April 2011

Starch gel electrophoresis was used to evaluate the allozyme diversity, population structure, and taxonomic relationships of two closely related taxa endemic to the Iberian Peninsula: Petrocoptis montsicciana O. Bolòs & Rivas Martínez, restricted to the pre-Pyrenean belt of Catalonia and Aragon, and Petrocoptis pardoi Pau, endemic to the Bergantes River basin (Autonomous Community of Valencia). Seven populations of the two species were sampled, and 16 interpretable loci were found. Considerable polymorphism, more than expected in endemic species, was detected in both taxa. The percentage of polymorphic loci (P) when the most common allele had a frequency of <0.95, the mean number of alleles per locus (A), and the expected panmictic heterozygosity (He) were slightly higher in P. montsicciana (P = 70.3, A = 2.2 and He= 0.239) than in P. pardoi (P = 56.3, A = 1.9 and He= 0.192). Strong divergence between populations was found in both species (GST= 0.376 in P. montsicciana and GST= 0.354 in P. pardoi) because of the geographic isolation of populations and limited seed and pollen dispersal. Most loci showed deviations from the Hardy-Weinberg equilibrium, probably as a consequence of genetic substructuring of populations. Low germination and renewal rates, and some anthropogenic activities such as road work, climbing, and massive collection are the main threats to these species.Key words: Petrocoptis montsicciana, Petrocoptis pardoi, Caryophyllaceae, allozyme electrophoresis, genetic diversity, conservation, endemic species.
The evolution of fruit in Scandiceae subtribe Scandicinae (Apiaceae)
Authors: Spalik Krzysztof , Wojewódzka Aneta , Downie Stephen R
Published: April 2011

Evolutionary relationships among 66 representatives of the family Apiaceae, including 37 species of tribe Scandiceae subtribe Scandicinae, were inferred from separate and combined analyses of fruit morphology and anatomy and nuclear ribosomal DNA internal transcribed spacer (ITS) sequences. Phylogenetic trees inferred from analysis of 35 fruit characters were not congruent to those derived from molecular data and, overall, had much lower bootstrap support values than the latter. Contrary to molecular data, fruit characters did not support the monophyly of subtribe Scandicinae. Fruit data do, however, corroborate the monophyly of nearly every genus within Scandicinae, the affinity of members of the "crown" cladeAnthriscus, Kozlovia (including Krasnovia and Neoconopodium), Geocaryum, Myrrhis, and Osmorhizathat had been identified in previous molecular analyses, and the sister group relationship between the "crown" clade and the genus Scandix. Phylogenies derived from the analysis of combined ITS and fruit characters were congruent to those inferred from molecular data alone. Reconstructions of ancestral character states using the results of the combined analysis suggest that among extant Scandicinae, the fruits of Athamanta have retained the most plesiomorphic characters. Evolutionary tendencies that have occurred in the fruits of Scandicinae include the broadening of the vascular bundles and vittae, the thickening of the cuticle and epidermal cell wall, the origin of bristles from hairs, the appearance of a pedicel-like appendage, the development of a long beak, and lateral wings. These changes are interpreted as adaptations to fruit dispersal and seed defense.Key words: Apiaceae, Scandiceae subtribe Scandicinae, ITS, fruit morphology.
The use of labelled cations to measure victorin-induced permeability changes
Authors: Gracen V. E. , Luke H. H. , West S. H. , Wallace A. T.
Published: April 2011

We have described a technique for using labelled cations to measure the induction of electrolyte leakage in victorin-sensitive oat root cells caused by the host-specific toxin, victorin. The technique provides a rapid and sensitive way to measure leakage of specific labelled ions. By using the technique, we have demonstrated that the 86Rb leakage follows the same pattern as electrolyte leakage, in general, after victorin treatments. CaCl2 at 50 mM concentrations inhibits victorin activity as measured by 86Rb leakage. 45Ca retention is not affected by victorin the same as 86Rb or electrolytes in general. Some possible implications of the differential effects of victorin on45Ca and 86Rb in relation to the calcium's role in membrane function are discussed.
Gaseous and volatile exudates from germinating seeds and seedlings
Authors: Vančura V. , Stotzky G.
Published: April 2011

The quantities of gaseous and volatile metabolites liberated by germinating seeds and seedlings appeared to be related, in general, to the amount of storage substances present in the seeds. Both qualitative and quantitative differences were found between various plant species and varieties of both angiosperms and gymnosperms. The release of volatile compounds preceded the appearance of the first root and, with most seeds, was greatest in the first 24 to 48 h. Organic volatiles could be detected, by gas chromatography, in as little as 5% of the atmosphere from one germinating seed. All seeds that were studied liberated ethanol, and most seeds evolved methanol, formaldehyde, acetaldehyde, formic acid, ethylene, and propylene. Propionaldehyde and (or) acetone was also evolved by cotton, pea, and yellow pine. The possible source of these volatile metabolites and their ecological implications are discussed.
Corticium centrifugum reisolated from fisheye rot of stored apples
Authors: Weresub Luella K. , Illman W. I.
Published: April 2011

One of the causal agents of fisheye rot of apples in cold storage, long known under the inapplicable name of Corticium centrifugum sensu Butler, is redescribed as Butlerelfia eustacei Weres, & Illman, gen. et sp. nov., named in honour of H. J. Eustace and L. F. Butler, who first made it known to science.
Electron microscopic study of oospore maturation and germination in an emasculate isolate of Saprolegnia ferax. 4. Nuclear cytology
Authors: Beakes Gordon W.
Published: April 2011

Changes in nuclear ultrastructure during the formation, maturation, and germination of oospores produced by an agamospermous (emasculate) isolate of Saprolegnia ferax are described. Oogonium nuclei undergo synchronous meiotic divisions which appear identical to those previously reported in antheridiate species. Fusion of two typical gametic nuclei result in the formation of a single, unusually large, restitution nucleus within delimited oospheres. During the activation phase of germination the nuclei undergo three or four successive, near synchronous, mitotic divisions which appear similar to those described in other oomycetes. There was no evidence to support the occurrence of zygotic meiosis. Some nuclei in germinating oospores contain unusual spheroidal and lamellar inclusions, whereas others have abnormally large, irregularly lobed, profiles. Nuclear autolysis was also a common event in germlings. These results are compared with those in other oomycetes and the evidence supporting automictic sexuality discussed.
Effects of O3and (or) fescue on ladino clover: interactions
Authors: Kochhar Medha , Blum Udo , Reinert R. A.
Published: April 2011

Various aspects of interactions between tall fescue and ladino clover were observed in the presence and absence of O3. Ozone reduced the growth of clover and fescue seedlings. Fescue seedlings were less sensitive to O3 than were clover seedlings. Leaf leachate from transplanted fescue plants inhibited the growth of clover. Nodulation of clover was reduced by leachate from fescue plants exposed to O3, but not by leachate from nonexposed fescue plants. The addition of fescue, clover, or fescue and clover debris to soil stimulated the growth of both clover and fescue. This stimulation was reduced or eliminated by O3. Root interactions of seedling fescue and clover had little effect on clover, but transplanted fescue and clover root interactions reduced the growth of clover. The direct and indirect effects of O3 and (or) fescue on clover are discussed.
Etude cinétique de quelques événements lies à une levée de dominance apicale par décapitation ou ablation de l'axe principal à différents niveaux chez la Tomate, Lycopersicum esculentum
Authors: Ngoc Kim Anh Ha
Published: April 2011

In intact tomato plants, axillary buds are completely inhibited by the main apex. A release from apical dominance is obtained by decapitation or excision of the main axis at different levels. These excisions lead to a wave of mitotic reactivation along the main stem which progresses in the basipetal way and is followed by an activation of axillary bud in the acropetal direction, from the base to the axillary bud apex. After release from apical dominance, axillary buds don't react equally. There is a basipetal gradient of their capacity of outgrowth. In the younger subapical axillary buds, mitotic reactivation is the first step observed (after 3 h); the cellular elongation occurs after 3–6 h, and foliar organogenesis begins only after 24 h. The basal axillary buds are reactivated much later. Adult leaves don't play any role on their axiliaries: the total defoliation of the plant does not lead to the outgrowth of all the axillary or cotyledonary buds.
The cytology of tetraploid "Bromus inermis'' and the Co colchicine-induced octoploid
Authors: Armstrong K. C.
Published: April 2011

A seed lot of Bromus obtained from the Botanic Garden of Novosibirsk, U.S.S.R., gave rise to fertile tetraploid plants, morphologically similar to natural octoploids of Bromus inermis. The cytology and morphology of this strain corresponds to that of a previously described tetraploid clone. The multivalent frequency in the Co generation of the colchicine-induced octoploids is significantly higher than that reported for natural octoploids. Possible explanations for this difference are discussed as it relates to the evolutionary origin of the natural octoploids.
Biomass and distribution patterns of conifer twig microepiphytes in a Douglas fir forest
Authors: Carroll George C. , Pike Lawrence H. , Perkins John R. , Sherwood Martha
Published: April 2011

Total cell volume estimates and species composition for twig microepiphytes are presented for four species of coniferous trees common in the Pacific Northwest. Fungal cell volumes per square centimetre were much greater on Pseudotsuga menziesii than on the other conifers sampled; population densities of algal cells were similar on all hosts. On P. menziesii, microbial populations build up as the twigs age, with total cell volumes at a maximum on 6- and 7-year-old twigs; thereafter total cell volumes decline as twig surface areas decline, although population densities remain high. When fungal cell volumes are expanded to tree and stand levels, estimates of 372 cm3/tree and 15 kg/ha are generated. These values are significant in comparison with estimated standing crops of epiphytic fungi on needles (30 kg/ha) and suggest that twig microepiphytes must be considered in any investigation on the role of epiphytes in nutrient cycling in coniferous forests.
Accumulation of the material containing the toxin cerato-ulmin on the hyphal surface of Ceratocystis ulmi
Authors: Takai Shozo , Hiratsuka Yasuyuka
Published: April 2011

Recovery of cerato-ulmin (CU) in the water extract from intact hyphae of Ceratocystis ulmi proved that it is present on the hyphal surface. Degrees of the accumulation of unidentified material on the cell surface of hyphae, together with CU recovery, varied from high, among isolates classified as distinct in CU production, to unmeasurable, among isolates classified as negligible in CU production. There was a correlation between the accumulation of unidentified material on the hyphal surface as observed under the scanning electron microscope (SEM) and recovery of CU from hyphal colonies. Most of the accumulated material was water-extractable, as is CU, and it is therefore concluded that the material accumulated on the hyphae of isolates classified as distinct in CU production does, indeed, contain CU.
Evidence for the presence of the toxin cerato-ulmin in the synnema head fluid of Ceratocystis ulmi
Authors: Takai S. , Richards W. C. , Davies Y. P. , Hiratsuka Y. , Krywienczyk J.
Published: April 2011

The presence of cerato-ulmin (CU) in the synnema head fluid (HF) of Ceratocystis ulmi was shown by the results of light and scanning electron microscope observation and by demonstration of the assembling and disassembling of structures characteristic of CU in the HF. Further, through the combined application of acrylamide gel electrophoresis and double diffusion techniques, CU was detected as the major protein in the HF.
Patterns of nutrient concentration in basidiocarps in western Washington
Authors: Vogt K. A. , Edmonds R. L.
Published: April 2011

Fruiting bodies and forest floor samples were collected and analyzed for N, P, K, Ca, Mg, Mn, and Na content in red alder, Douglas-fir, western hemlock, and Pacific silver fir ecosystems in western Washington. Different genera and species of fungi showed wide variation in the capability of concentrating nutrients within their fruiting bodies. Ranges of nutrient content for fruiting bodies were 0.66–11.27% N, 0.04–2.39% P, 7 – 32 080 ppm Ca, 2975 – 57 404 ppm K, 10–7096 ppm Mg, 3–1727 ppm Mn, 15–3975 ppm Fe, 18–6763 ppm Na, and 15–278 ppm Zn. Nitrogen, P, and K were concentrated in significantly higher levels in fruiting bodies versus the forest floor in all ecosystems. Nitrogen and K were concentrated at levels higher than 1% while P, Ca, Mg, Mn, and Na were concentrated at levels less than 1% of the dry weight of the fruiting bodies. Calcium was not concentrated by fungi in sporocarps, except for Armillariella mellea rhizomorphs (3.2% on dry weight basis). Lignicolous fungi were lower in N and K than nonlignicolous fungi.
Comparative histological basis of sun and shade leaf dimorphism in Helianthus annuus
Authors: Dengler Nancy G.
Published: April 2011

The development processes which give rise to the histological differences between leaves expanding under full daylight and 25% daylight are described for Helianthus annuus. Generally the pattern of cell division and cell enlargement in shaded leaves lags behind that in unshaded leaves by about 2 days. There is no significant difference in the amount of cell enlargement in the paradermal plane in the epidermis and palisade layers of shaded leaves as compared with leaves expanding in full sunlight. However, cell division in all cell layers occurs at greater rates in unshaded leaves, resulting in greater final leaf area. Cell elongation in both palisade layers is of longer duration and occurs at a greater rate in unshaded leaves and is closely correlated with increase in leaf thickness. The volumes of palisade and spongy mesophyll are significantly greater in unshaded leaves than in shaded leaves, but the relative proportions of each tissue type does not change significantly. However, in shaded leaves there are fewer spongy mesophyll cells per unit area and a greater proportion of intercellular space than in unshaded leaves. Stomata are formed over the same time period in leaves grown at both intensities, but differentiate at greater rates in leaves grown in full sunlight, giving greater final stomatal density. These observations indicate that a sun plant such as Helianthus responds phenotypically to lowered light intensity primarily by a reduction in cell division (resulting in reduced leaf area), and secondarily by modifying cell expansion in a plane perpendicular to paradermal resulting in the characteristic anatomy of shaded leaves.