bluuebunny/crossref_metadata_2025 huggingface dataset:
Population biology of west coast Cakile maritima: effects of habitat and predation by Peromyscus maniculatus
Authors: Boyd Robert S.
Published: December 2007

Survival patterns of Cakile maritima Scop. ssp. maritima seedlings in adjacent open-beach and foredune habitats differed, with significant cohort and seasonal effects only for open-beach plants. Open-beach plants were usually killed by fall storms. Some foredune plants (5.3%) survived into a second reproductive season, producing 85% of mature fruits in the foredune. Peromyscus maniculatus (Wagner) removed 95% of fruits matured by foredune plants. Sand burial of fruits increased their chances of escaping predation. Burial was 52-fold more likely for fruits on open-beach plants compared with foredune plants, resulting in lower seed predation on the open beach. Germination from P. maniculatus caches produced 63% of foredune plants, but they represented only 0.002% of all removed seeds. Cache plants had lowered survival relative to noncache plants, so that seed dispersal by P. maniculatus did not benefit C. maritima. Both foredune and open-beach populations were likely to decline if transition patterns among age-classes and fruit production rates observed in 1983 and 1984 remained constant. Because of high fruit production by overwintering plants, foredune plants produced more fruits than needed to maintain plant numbers, but predation by P. maniculatus reduced seed survival to less than 20% of the replacement rate for that habitat. Key words: Cakile maritima, Peromyscus maniculatus, plant–animal interactions, seed dispersal, seed bank, plant demography.
Importance of hydrochory in structuring plant communities along rivers
Authors: Nilsson Christer , Gardfjell Maria , Grelsson Gunnel
Published: December 2007

Using wooden cubes as experimental seed mimics we tested whether differences in seed deposition among riverbank sites predictably affect the structure of riparian vegetation. Although cube deposition was not interpretable in terms of environmental variables like current velocity, riverbank width, and substrate, it was related to species composition of the riparian vegetation. We found an excess of species with short-floating seeds among those that were most frequent in sites capturing few cubes and an excess of species with long-floating seeds among those that were most frequent in sites capturing many cubes. This result provides the first evidence that water dispersal interacting with floating time may play a role in small-scale structuring of riparian plant communities. Key words: floating time, hydrochory, riparian vegetation, river, seed mimics, seed deposition.
An immunofluorescent cytochemical technique applying micromanipulation to detect microtubules in plant tissues inoculated with fungal spores
Authors: Kobayashi Issei , Kobayashi Yuhko , Yamaoka Naoto , Kunoh Hitoshi
Published: December 2007

An immunofluorescent cytochemical technique to detect microtubules was developed to examine the involvement of microtubules in incipient responses of barley coleoptile cells to fungal attacks. Infiltration of antibodies into target cells was promoted by scratching cell walls of chemically-fixed coleoptile cells with a micromanipulator. In uninoculated control cells, cortical microtubules were arranged obliquely or transversely to the longitudinal axis of the cells. On the other hand, in coleoptile cells which had been fixed 8–10 h after inoculation with a nonpathogen, Erysiphe pisi, microtubules gathered in coleoptile cells beneath mature appressoria of the fungus. When coleoptiles had been fixed 12 h after inoculation, many of the microtubules gathered around an incipient, small papilla, giving a network appearance. The present technique would be helpful for studying the role of microtubules in host cell responses to fungal attack. Key words: microtubules, immunofluorescent cytochemistry, barley coleoptile, Erysiphe pisi.
Growth response of two Sphagnum species to photoperiod
Authors: Li Yenhung , Glime Janice M.
Published: December 2007

Growth of two Sphagnum species, S. magellanicum Brid. and S. papillosum Lindb., was studied in the laboratory, field, and greenhouse in relation to photoperiod. Short days (less than 10 h light) induce both species into dormancy. Both species exhibit a high correlation of growth in length and biomass with photoperiod, having maximum length and biomass increase under continuous illumination. Likewise, the ability to lower pH increases with photoperiod. The greater increase in biomass of S. papillosum under 18-h photoperiods could provide short-term niche partitioning. Key words: Sphagnum, photoperiod, growth, pH-lowering ability.
Detection of a subfamily of genes within the soybean nodulin-A multigene family
Authors: Gottlob-McHugh Sylvia G. , Johnson Douglas A.
Published: December 2007

A soybean cDNA clone, 15-9-A, corresponding to a new nodule-specific gene was isolated. 15-9-A corresponds to an abundantly transcribed 1.0-kb mRNA that could first be detected in root nodules at about 10 days following inoculation with Bradyrhizobium japonicum. This clone was found to be very closely related to, but distinct from, Ngm-20, a member of a soybean nodulin multigene family. We have used oligonucleotide probes to detect an additional closely related gene, Ngm-20r, which is expressed as a 0.8-kb mRNA. 15-9-A, Ngm-20, and Ngm-20r appear to form a subfamily within the larger nodulin multigene family. Results derived from sequence analysis and hybridization experiments suggest that gene conversion may have played a role in the evolution of this subfamily. Key words: cDNA clone, gene conversion, multigene family, nodule specific, soybean.
Somatic incompatibility in dikaryotic–monokaryotic and dikaryotic pairings of Echinodontium tinctorium
Authors: Wilson A. D.
Published: December 2007

Somatic incompatibility in dikaryotic–monokaryotic (di–mon) and dikaryotic pairings of Echinodontium tinctorium was investigated in vitro on 4.5% malt agar. Antagonistic reactions of varying intensity occurred in all pairings between 12 allopatric dikaryons from Idaho and Arizona, between 14 sib-composed dikaryons from two Idaho sites, and in over 95% of pairings between sympatric dikaryons from separate trees at each location. Antagonistic reactions in dikaryotic pairings macroscopically appeared as dark reaction lines in the agar and aversion zones (barrage reactions) with hyphal massing on each side of the aversion zones. Self-crosses of dikaryons were somatically compatible, and hyphal anastomoses were common. Hyphal anastomoses were rare in the aversion zones between somatically incompatible dikaryons. Somatic incompatibility occurred in 51% of 89 di–mon pairings between 29 monokaryotic isolates and 7 sib-composed dikaryons from the same parent. Somatically incompatible di–mon pairings were characterized by hyphal massing in the contact zone and reaction lines on the reverse, but they lacked barrage reactions. Clamp connections formed in 54% of all di–mon crosses and at similar frequencies when no antagonistic reactions were present (55%) or when only hyphal massing occurred (53%), but they formed less frequently (33%) when dark reaction lines were present. The potential applications of these findings to epidemiological studies are discussed. Key words: Echinodontium, somatic incompatibility, epidemiology, Buller phenomenon, dikaryotic–monokaryotic, wood decay.
Electron microscopy of barley root infection by the fungal pathogen Bipolaris sorokiniana
Authors: Carlson H. , Stenram U. , Gustafsson M. , Jansson H.-B.
Published: December 2007

An electron microscopic investigation of barley roots infected in vitro by Bipolaris sorokiniana showed the existence of an extracellular sheath on germ tubes and appressoria attached to the root surface. Growth of the fungus in the epidermis and outer cortex was predominantly intracellular, whereas in the inner cortex the hyphae observed were mainly intercellular. Hyphae could not be detected in the stele 24 or 72 h after inoculation. Enzymatic activity in the apex of penetration hyphae is a possible explanation of the electron-dense areas seen in host cell walls 72 h after inoculation. Separation of plasmalemma from cell wall and degeneration of host nuclei and mitochondria were other infection-induced changes commonly seen. A host response to fungal infection involved the development of papillae between the plasma membrane and cell wall of the plant as well as around fungal hyphae. Key words: Bipolaris sorokiniana, Cochliobolus sativus, Helminthosporium sativum, Hordeum vulgare, barley, root, microscopy.
Pectinolytic activity and isozymes in European Armillaria species
Authors: Wahlström Kjell , Karlsson Jan-Olof , Holdenrieder Ottmar , Stenlid Jan
Published: December 2007

Pectinolytic activities in Armillaria ostoyae, Armillaria mellea, Armillaria gallica, Armillaria borealis, and Armillaria cepistipes were assessed by measuring the ability of fungal strains to reduce the viscosity of their pectic growth media. Isozyme patterns of pectin esterases and polygalacturonases were determined directly from the culture filtrate. A total of 94 strains, representing isolations from various parts of Europe, were analyzed for their isozyme patterns. Armillaria mellea and A. borealis caused a 50% reduction in viscosity within 7 and 9 days, respectively. Growth medium from the other species were slower to reach the 50% level, i.e., means were 13 days for A. ostoyae and 17 days for A. cepistipes and A. gallica. All species produced more isozymes on spruce wood than on citrus pectin medium, and pectic isozyme patterns differed between media. The pectic isozyme pattern for A. mellea differed distinctly from those of the other four species by having two bands of polygalacturonase not found in the others. The pectic isozyme patterns of the other four species were separated using multivariate analysis. The value of such analyses for use in distinguishing between European Armillaria species is discussed, as is the relation between enzyme activity and fungal pathogenicity. Key words: root rot, diagnostic tests, Agaricales, polygalacturonase, pectin esterase.
Septal and lateral pores in the fungal endophytes of two pasture grasses
Authors: Philipson Melva N.
Published: December 2007

Septal spores of two fungal endophytes of Lolium and Festuca are more elaborate, in presporulation hyphae, than the simple pore of many ascomycetous fungi. The pore of the Gliocladium-like endophyte consists of a dome-shaped, membraneous cap formed of vesicle-like structures that encloses the aperture. Woronin bodies in the pore vicinity appear to bear fine fibrillar processes extending radially from their surfaces, often making contact with the pore cap. In septal pores of the Phialophora-like endophyte the hemispherical boundary of the pore lumen bears an irregular electron-opaque deposit, and fibrillar processes from Woronin bodies have not been observed. Lateral pores occur in both endophytes in areas of massed contiguous hyphae. Reduction of two hyphal walls to a narrow strip occurs at the pore site. Development of a pore between the hyphae probably results from degradative activities of a fibrillar band extending between two Woronin bodies, one in each hypha, and penetrating the dividing wall. In lateral pore formation, involvement of Woronin bodies with an associated fibrillar band at the future pore site may support their enzymatic nature. Similarly, in septal pores of the Gliocladium-like endophyte, fibrillar extensions from Woronin bodies to the septal pore cap may indicate enzymatic control of the pluglike contents of the pore. Key words: fungi, septal pores, lateral pores, ultrastructure, endophytes, grasses.
Environmental regulation of nitrogen fixation in a high arctic lowland ecosystem
Authors: Chapin David M. , Bliss L. C. , Bledsoe L. J.
Published: December 2007

This study examined spatial and temporal variation in cyanobacterial nitrogen fixation and the environmental regulation of this variation at Truelove Lowland, Devon Island, N.W.T. Acetylene reduction rates of soil–plant cores from a variety of plant communities were measured under uniform conditions of light and temperature during the 1987 and 1988 growing seasons. Concurrent measurements of soil moisture and extractable nitrogen and phosphorus were also made. Effects of temperature, moisture, and phosphorus were examined in manipulative experiments. Acetylene reduction rates were highest in brackish environments, intermediate in mesic to hydric terrestrial and in aquatic communities, and lowest on xeric beach ridges. Rates generally increased during early season, then decreased through mid to late season. Among the three parameters examined, rates were most highly correlated to soil moisture. The temperature optimum for fixation was near 20 °C. There was a strong, but reversable, depression in acetylene reduction in response to experimental desiccation, and weekly phosphorus fertilization had a strong positive effect on fixation rates. The highest fixation rates along the marine shoreline were associated with high phosphorus input from marine algae and greater biomass of cyanobacteria. Because of the overriding importance of moisture, changes in nitrogen and phosphorus levels accompanying ecosystem development do not appear to strongly control nitrogen fixation in terrestrial, nonbrackish sites in this polar desert oasis. Key words: nitrogen fixation, environmental regulation, Devon Island, High Arctic, Nostoc commune, cyanobacteria.
Chromosome complement and nucleoli in the Festuca pallescens alliance from South America
Authors: Dubcovsky Jorge , Martínez Arturo J.
Published: December 2007

The karyotypes, chromosomes with secondary constrictions, and maximum number of nucleoli of 14 hexaploid (2n = 42) species of Festuca native to South America are described to complete the cytological characterization of the Festuca pallescens alliance. The species analyzed were Festuca acanthophylla E. Desv., Festuca argentinensis (St.-Yves) Türpe, Festuca chrysophylla Phil., Festuca circinata Griseb., Festuca cirrosa (Speg.) Parodi, Festuca gracillima J. D. Hook, Festuca kurtziana St.-Yves, Festuca monticola Phil., Festuca pallescens (St.-Yves) Parodi, Festuca scabriuscula Phil., Festuca scirpifolia (Presl.) Kunth, Festuca thermarum Phil., Festuca tunicata E. Desv., and Festuca ventanicola Speg. They have symmetric and uniform karyotypes but differed (p < 0.01) in arm ratio values. The species had similar maxima in the number of nucleoli in the root tips (9–12), microspores (5–7), and chromosomes with secondary constrictions (10–14). The arrangement of chromosomes in homomorphic pairs and their meiotic behaviour suggest that the species are allohexaploids. The size, shape, and number of chromosomes bearing secondary constrictions confirm that these species are members of the same alliance. Key words: Festuca, karyotype, nucleolus, chromosome pairing.
Incipient decay of Quercus serrata sapwood by Lentinus edodes and its inhibition by an antagonistic hyphomycete, Leptodontidium elatius
Authors: Tsuneda A. , Maekawa N. , Ohira I. , Furukawa I.
Published: December 2007

Incipient decay of Quercus serrata by Lentinus edodes and its inhibition by Leptodontidium elatius were investigated by scanning electron microscopy. Rapid accumulation of L. edodes hyphae in earlywood vessels was a prerequisite to efficient decay of sapwood. In the early stages of decay, selective removal of lignin and other amorphous wall components occurred in the vessels and surrounding tissues, including vasicentric tracheids and wood fibres. Thus, bundles of cellulose microfibrils, having lateral dimensions of 15–50 nm, became recognizable. Disintegration of cellulose microfibril bundles appeared to begin with longitudinal and (or) transverse splitting of the bundles, and then the walls became progressively thinner. In ray parenchyma cells, end walls were susceptible to the fungal degradation, but lateral walls, particularly the innermost layer, were relatively resistant. Hyphae of L. elatius grew in close contact with the vessel wall and exuded slime material to create a distinct microarea (mycosphere) around them. In the vessels precolonized by this hyphomycete, the growth rate of L. edodes hyphae was drastically reduced to less than 20% of that in antagonist-free vessels. Possible roles of the slime material in this antagonism are discussed. Key words: wood decay, Lentinus edodes, Leptodontidium elatius, antagonism, mycosphere.
Allelopathic potential of western coneflower (Rudbeckia occidentalis)
Authors: Ferguson Dennis E.
Published: December 2007

Water extracts and volatiles from western coneflower (Rudbeckia occidentalis Nutt.) were tested for allelopathic potential under controlled laboratory conditions. Test species were lettuce (Lactuca sativa, Lilly Miller Great Lakes), lodgepole pine (Pinus contorta Dougl. ex Loud.), and Engelmann spruce (Picea engelmannii Parry ex Engelm.) using four treatments (leaves–stems, solid caudex, rotting caudex, and control). Water extracts reduced radicle lengths of seeds but had little effect on germination. Volatiles reduced or delayed germination but had little effect on radicle lengths of germinants. Key words: phytotoxin, Pinus contorta, Picea engelmannii.
Isoetes ×jeffreyi, hyb.nov., a new Isoetes (Isoetes macrospora × Isoetes riparia) from Quebec, Canada
Authors: Britton Donald M. , Brunton Daniel F.
Published: December 2007

A new interspecific hybrid in Isoetes, Isoetes macrospora Dur. × riparia Engelm., is delineated and described from Papineau County, Quebec, Canada by means of cytology and scanning electron microscopy of spores. Isoetes ×jeffreyi D. M. Britton and D. F. Brunton, hyb.nov., is the name proposed for this taxon. It is a heptaploid (7x; 2n = 77) and is believed to be sterile. Hybrid plants demonstrate hybrid vigour and have polymorphic, frequently aborted spores that demonstrate size and surface ornamentation features intermediate between the putative parents. Five populations of the hybrid were found growing with either, neither, or both putative parents at the sand-bottomed outlet of a large lake. Active silt and sand erosion and deposition caused by swirling lake currents appears to facilitate opportunities for hybridization. Isoetes ×jeffreyi is expected to be a rare taxon owing to the restricted sympatric area of the putative parents and their contrasting habitat preferences. Key words: Isoetes, Isoetes macrospora, Isoetes riparia, Isoetes ×jeffreyi, hybrid, Quebec.
Embryology of Calypso bulbosa. II. Embryo development
Authors: Yeung Edward C. , Law Sandra K.
Published: December 2007

Calypso bulbosa is a terrestrial orchid that grows in north temperate regions. After fertilization, the zygote enlarges and grows towards the chalazal end of the embryo sac. An unequal cell division gives rise to a smaller terminal cell and a larger basal cell. A constriction forms in the basal cell. Further growth results in a U-shaped embryo. Two patterns of initial terminal cell division have been observed. In a majority of developing embryos, the terminal cell first divides periclinally and then anticlinally. In approximately 5% of the embryos, the initial division of the terminal cell is anticlinal. Despite differences in early cell division patterns, subsequent embryo development is the same. The suspensor consists of a large, highly vacuolated basal cell and a 4-celled filamentous region. Highly conspicuous starch granules are present within the basal cell of the suspensor. At maturity, the embryo proper is small, consisting of approximately 24 cells and lacking marked differentiation of the apical end. Starch and lipid are the main storage products within the embryo proper. Key words: Calypso orchids, embryo development, suspensor.
Regulation of accumulation of mRNAs encoding a 20-kDa oil-body protein in microspore-derived embryos of Brassica napus
Authors: Rooijen Gijs J. H. van , Wilen Ronald W. , Holbrook Larry A. , Moloney Maurice M.
Published: December 2007

A 990-bp DNA fragment (OB990) encoding part of a 20-kDa Brassica napus oleosin was used to investigate the expression of this gene in microspore-derived embryos. Southern blot analysis of total genomic B. napus DNA indicated that the oleosins comprise a multigene family in B. napus. Northern analysis indicated that oleosin mRNAs are seed-specific and accumulate in zygotic and microspore-derived embryos. Microspore-derived embryos were used to study the hormonal and osmotic regulation of this oleosin gene family. Oleosin mRNAs can be found as early as heart stage. The accumulation of these mRNAs increased dramatically after the application of 10 μM abscisic acid or high osmoticum (12.5% sorbitol). Time course experiments to study the induction of oleosin expression by 10 μM abscisic acid and 12.5% sorbitol demonstrated that the abscisic acid and sorbitol effects occur concurrently. This is distinct from the accumulation of napin storage protein mRNAs after the same treatments. When 10 μM jasmonic acid was applied, the oleosin mRNA accumulation increases significantly. The possibility that jasmonic acid and abscisic acid may function as intermediaries of the imposed osmotic stress is discussed. Key words: Brassica napus, gene regulation, microspore-derived embryos, osmoticum, abscisic acid, jasmonic acid.
Studies of Capsicum annuum seeds: structure, storage reserves, and mineral nutrients
Authors: Chen Ping , Lott John N. A.
Published: December 2007

Storage reserves of Capsicum annuum (sweet pepper) seeds were studied using light microscopy, histochemical techniques, and electron microscopy. The seed had mainly protein and lipid as storage reserves. Starch was not detected. Thickened endosperm cell walls likely are a store of nonstarch polysaccharide. Protein bodies had protein crystalloids and globoid crystals as inclusions in the proteinaceous matrix. Protein bodies in embryo tissues varied greatly in size both inter- and intra-cellularly, while endosperm protein bodies were similar in size. Energy dispersive X-ray analysis and neutron activation analysis revealed the element content of C. annuum seeds. The presence of P, K, and Mg in all globoid crystals is consistent with their being phytin-rich. The average ratios of Mg:K, based on peak-to-background values for globoid crystals, were lowest in provascular tissues, where most globoid crystals were very small, and were highest in ground meristem tissues, where globoid crystals were large. Fe, Zn, Mn, Ca, S, and Cl were detected in some globoid crystals. In globoid crystals of both the cotyledon and hypocotyl – radicle axis, Fe was always detected in protoderm cells, was occasionally detected in ground meristem cells, and was never detected in provascular cells. Neutron activation analysis results showed that Mg, K, S, and Cu were higher in the embryo than in the endosperm, while Cl, Na, and Ca were higher in the endosperm. Mn had similar concentrations in both tissues. Key words: Capsicum annuum, storage reserves, protein body, globoid crystal, phosphorus, seed.
Agaricales of the Hawaiian Islands. I. Marasmioid fungi: new species, new distributional records, and poorly known taxa
Authors: Desjardin Dennis E. , Wong George J. , Hemmes Don E.
Published: December 2007

Nine species of marasmioid fungi are described from material collected in the Hawaiian islands: Marasmiellus pacificus, Marasmius pseudobambusinus var. hawaiiensis, and Marasmius radiatus are described as new; Marasmius sp. is described provisionally; Gloiocephala epiphylla, Marasmiellus mesosporus, and Marasmius androsaceus are first reports for the Hawaiian Islands; Marasmius sphaerodermus and Tetrapyrgos nigripes are redescribed based on Hawaiian specimens. Most taxa are illustrated and compared with phenetically similar taxa. This brings the total number of agarics reported from the Hawaiian Islands to 101 taxa, 23% of which are marasmioid fungi. Key words: Agaricales, Hawaiian Islands, marasmioid fungi.
Relationships, derived from optimum alignments, among amino acid sequences of plant peroxidases
Authors: Tyson Hugh
Published: December 2007

The amino acid and (or) DNA sequences of 13 plant peroxidases (EC 1.11.1.7), which include isozymes within species, are currently available in data bases; all have similar lengths of approximately 300 amino acids. Sequence relationships among these 13, plus 2 microbial peroxidases of similar length, were examined. The 15 sequences were compared in all 105 pairwise combinations using optimum alignment procedures. Gap penalties were determined from analysis of penalty change effects. Distances between sequences generated by optimum alignments were analysed by clustering techniques to generate dendrograms. Specific distances, which provided pairwise distance measurements independent of the average distance for a sequence, were used to evaluate sequence similarities; closely related sequences produce closely correlated specific distances. Among the seven plant species, five subgroups were established: (1) horseradish isoperoxidases, (2) turnip and wheat, (3) cucumber and tobacco, (4) potato and tomato, and (5) in which cytochrome c peroxidase showed some similarity to ligninase, but both were only distantly related to plant peroxidases. Horseradish isoperoxidases were related to sequences in subgroups 2, 3, and 4 but resembled subgroups 2 and 3 more closely than 4. Subgroup 2 was more related to 3 than any other. Key words: plant peroxidases, sequence relationships, peroxidase profiles.
Movement of cytoplasmic hypovirulence agents in chestnut blight cankers
Authors: Shain L. , Miller J. B.
Published: December 2007

Chestnut blight cankers, initiated with virulent methionine auxotrophic strains of Cryphonectria parasitica, were challenged by placing one or two discs of agar and mycelium of prototrophic hypovirulent strains at their base. Movement of hypovirulence agents was confirmed by recovery of an isolate that exhibited the typical morphology of the introduced hypovirulent strain on media with methionine but little or no growth on media without methionine. Cultures from bark showed that the hypovirulent agent moved through mycelium around the circumference of cankers within 3 weeks when the virulent and challenging hypovirulent were vegetatively compatible. Conversion of the mycelium in the canker interior proceeded more slowly. Conversion of mycelium also was delayed, but eventually occurred, when virulent and hypovirulent inocula differed in vegetative compatibility. Conidia, however, continued to yield virulent, methionine-requiring cultures up to 65 weeks after challenge, even though underlying bark frequently yielded hypovirulent, methionine-requiring cultures. This disinclination of hypovirulent agents to enter the asexual apparatus in cankers may contribute substantially to the observed ineffective dissemination of hypovirulence in the natural range of American chestnut. Exploitation of those hypovirulent agents that can enter conidia in cankers may enhance the biological control of chestnut blight by hypovirulence. Key words: biological control, Cryphonectria parasitica, Endothia parasitica, Castanea dentata.
Patterns of seed weight distribution and germination with time in a weedy biotype of proso millet (Panicum miliaceum)
Authors: Kane Marguerite , Cavers Paul B.
Published: December 2007

Three plants from each of 10 populations of the black biotype of proso millet (Panicum miliaceum) were grown in a common garden in London, Ontario. Seeds were collected from individual plants as they ripened. Each seed was identified as to location on the plant and weighed separately. Mean seed weight decreased over the growing season, both on individual inflorescences and on entire plants. Despite this trend, seeds at the upper end of the weight range were produced throughout the season. The decline in the mean resulted from an increasing proportion of smaller seeds. There was also increased variability in seed weight later in the growing season. In subsequent germination tests there was no discernable relationship between total percent viability and date of seed ripening. Total percent viability was above 70% for each sampling date. Key words: seed weight, positional effects, proso millet, germination, seasonal variation.
Vegetative growth and sporulation of Bipolaris sorokiniana on infected leaves of Poa pratensis exposed to postemergence herbicides
Authors: Hodges Clinton F.
Published: December 2007

Poa pratensis was exposed to the postemergence herbicides 2,4-D, MCPP, and dicamba at concentrations of 10−6 M applied to the soil surface. The four youngest leaf blades were inoculated with Bipolaris sorokiniana and subsequently detached to determine the effect of the herbicides on vegetative hyphal growth and sporulation on the leaf-blade tissue. Hyphal growth from infected leaf disks cut from detached leaves was stimulated by 2,4-D and dicamba. MCPP did not affect hyphal growth. All herbicides increased sporulation by B. sorokiniana on the detached leaves. Increases in sporulation did not differ between 2,4-D and MCPP. Dicamba induced the heaviest sporulation on leaf blades. Key words: dicamba, MCPP, mecoprop, 2-methoxy-3,6-dichlorobenzoic acid, 2(2-methyl-4-chlorophenoxy)propionic acid, 2,4-dichlorophenoxyacetic acid.
Comparative leaf development of conventional and semileafless peas (Pisum sativum)
Authors: Côté Richard , Gerrath Jean M. , Posluszny Usher , Grodzinski Bernard
Published: December 2007

Comparative leaf development of conventional (cv. Improved Laxton's Progress) and semileafless (cv. Curly) peas was studied three-dimensionally, from initiation to maturity. The pattern of initiation of leaf primordia, stipules, and the pairs of lateral leaflet and tendril primordia is the same for both cultivars. However, their respective developmental pathways diverge by the time four pairs of lateral primordia have formed. In the conventional cultivar, the basal lateral primordia become increasingly dorsiventral as they develop into leaflets. Distal lateral primordia retain a cylindrical form and develop into tendrils. In contrast, basal first-order lateral primordia of the semileafless cultivar retain a cylindrical form and initiate second-order primordia, first in pairs, then in an alternate pattern. These second-order primordia develop into tendrils. Distal lateral primordium initiation and development are the same in both cultivars. Macroscopic development was subdivided into three stages based on tendril function. Stage I is an elongation phase during which the coiling response is not yet exhibited. During stage II, the tendrils are thigmotropic and retain their capacity to elongate. By stage III the tendrils have completed coiling and they no longer respond to thigmotropic stimuli. Stage I lasts an average of 1.4 ± 0.1 days in 'Improved Laxton's Progress' and 2.1 ± 0.1 days in 'Curly' from emergence from the stipule. Stage II may last up to 8 days, with an average of 6.4 ± 0.2 and 6.9 ± 0.3 days for 'Improved Laxton's Progress' and 'Curly', respectively, under greenhouse conditions for both cultivars. Key words: peas, Pisum sativum, leaf development, tendrils, afila.
Ustilago spp. pathogenic on Aegilops. III. Ustilago phrygica, with a descriptive key to all three Ustilago spp. on Aegilops
Authors: Nielsen J.
Published: December 2007

Examination of herbarium specimens, studies of biology and host range, and interspecific hybridization showed that Ustilago hordei-criniti, Ustilago tuberculata, and Ustilago mesatlantica are conspecific with Ustilago phrygica. Within this species there are strains that are specialized either on Taeniatherum caput-medusae or on one or more of the Aegilops species Aegilops cylindrica, Aegilops tauschii, and Aegilops triuncialis; on these hosts there is specialization on the species level. Other hosts are species of Agropyron, Elymus, and Hordeum. Optimum temperature for spore germination is approximately 30 °C; ellipsoidal monokaryotic haploid sporidia are produced by each cell on the stout, four-celled promycelium. A brownish pink pigment diffuses into the medium if potato dextrose agar is used to culture sporidial isolates. The species has the same bipolar mating alleles as, and is thus compatible with, nine other graminicolous Ustilago spp. Infection of the host occurs through the coleoptiles of very young seedlings. The strains specialized on Aegilops pose no threat to cultivated wheat. To help identify future collections of any of the three Ustilago spp. on Aegilops, their key characteristics are summarized. Key words: Aegilops, Taeniatherum, smut, Ustilago phrygica, synonymy, host range.
Role of temperature and light in the germination ecology of buried seeds of weedy species of disturbed forests. I. Lobelia inflata
Authors: Baskin Jerry M. , Baskin Carol C.
Published: December 2007

Lobelia inflata L. is a weedy species that may be abundant in disturbed forest sites. Temperature and light requirements for germination were determined at 12-h daily thermoperiods of 15:6, 20:10, 25:15, 30:15, and 35:20 °C for seeds exhumed after 0–28 months (September 1987 to February 1990) of burial in soil at near-natural temperatures. At maturity in autumn 1987, 2–15% of the seeds germinated after 15 days incubation at the five thermoperiods in light but 0% germinated in darkness. By January 1988, 68–100% of the seeds germinated in light at all thermoperiods except 15:6 °C. Germination at 20:10, 25:15, and 30:15 °C did not decrease to below 60% during the remainder of the study, and germination at 35:20 °C was less than 60% only four times. Germination at 15:6 °C was erratic with peaks in spring 1988, and in spring to early summer and autumn 1989. Regardless of the season in which seeds were exhumed, they did not germinate in darkness. In a laboratory study, stratification at 5 °C broke dormancy but did not substitute for the light requirement. Seeds of L. inflata have the potential to form long-lived seed banks, and buried seeds can germinate at any time during the growing season if exposed to light. Key words: seed dormancy, seed germination, buried seeds, Lobelia inflata, stratification.
Esterase activity and structural heterogeneity in patatin from a wild potato species
Authors: Racusen David , Racusen Richard
Published: December 2007

Analysis of protein extracts of tubers from the potato species Solanum berthaultii revealed that they contain two types of patatin. One was a highly glycosylated form that exhibited weak esterase activity, and the other resembled the low-carbohydrate – strong esterase form that is typical of most potato cultivars. Though the function of patatin is unknown, the production of high- and low-carbohydrate forms may be under some form of developmental regulation; we observe considerable variation in the levels of expression in tubers taken from single plants. Key words: patatin, glycoprotein, esterase, Solanum berthaultii, Solanum tuberosum.
Plant cell wall-lysing enzymes in the apoplast of tomato leaves infected with Fulvia fulva
Authors: Aldington Suzanne , Fry Stephen C.
Published: December 2007

Apoplastic fluid recovered from healthy (uninfected) tomato leaves and from leaves infected with races of Fulvia fulva (Cooke) Ciferri (syn. Cladosporium fulvum (Cooke)) contained heat-labile lytic activities that solubilised carbohydrates from plant cell walls. Total activity was slightly enhanced in apoplastic fluid from infected plants. Material solubilised from uniformly 14C-labelled plant cell walls by apoplastic fluid from compatible and incompatible interactions and from the uninfected plant was analysed. 14C-Labelled poly-, oligo-, and mono-saccharides were detected, suggesting that both exo- and endo-hydrolase activities were present; endoactivity predominated during the early stages of infection. Fluid collected from incompatible interactions as early as 5–7 days postinoculation contained enhanced levels of an activity that solubilised arabinose-rich polysaccharide; by 9–11 days postinoculation, this activity had decreased and was comparable to that of the healthy plant. A similar activity was also seen in fluid from compatible interactions, but this was enhanced slightly later in the infection and increased rapidly during days 9–11 postinoculation. We suggest that the early and short-lived enhanced expression of an endohydrolase that attacks an arabinose-rich polymer may be related to disease resistance. Key words: tomato, Fulvia fulva (Cooke) Ciferri (syn. Cladosporium fulvum (Cooke)), apoplastic fluid, cell wall degrading enzymes, compatibility, oligosaccharin.
Ultrastructure of meiosis and the spindle pole body cycle in freeze-substituted basidia of the smut fungi Ustilago maydis and Ustilago avenae
Authors: O'Donnell Kerry
Published: December 2007

Meiosis in the smut fungi Ustilago maydis and Ustilago avenae (Basidiomycota, Ustilaginales) was studied by electron microscopy of serial-sectioned freeze substituted basidia. At prophase I, a spindle pole body composed of two globular elements connected by a middle piece was attached to the extranuclear surface of each nucleus. Astral and spindle microtubules were initiated at each globular element at late prophase I to prometaphase I. During spindle initiation, the middle piece disappeared and interdigitating half-spindles entered the nucleoplasm, which was surrounded by discontinuous nuclear envelope together with perinuclear endoplasmic reticulum. Kinetochore pairs at metaphase I were analyzed to obtain a karyotype for each species. The meiotic spindle pole body replicational cycle is described. Key words: electron microscopy, freeze-substitution, meiosis, Ustilago, spindle pole body.
Trichoderma atroviride
Authors: Bissett John
Published: December 2007

Trichoderma atroviride Karsten is redescribed from the type collection and recent isolates. Key words: Trichoderma atroviride, Hypocrea sp., taxonomy.
Trends in the pollination ecology of the Orchidaceae: evolution and systematics
Authors: Tremblay Raymond Louis
Published: December 2007

Reduction in the number of pollinator species per plant species is a mechanism that may lower the cost of pollen transfer. Using efficient pollinators may have an evolutionary significance. It is hypothesized that an evolutionary trend from many pollinators to few pollinators per plant species should be observable when species from ancestral versus recently derived monophyletic taxon are compared. Three different orchid phylogenetic sequences are used; two of the phylogenies show a reduction in the number of pollinator species per orchid species from the most ancestral to the most recently derived subfamilies. The third classification did not show this trend. It is thus possible to observe macroevolution of pollinator specialization of a monophyletic plant taxon. Key words: evolution, pollination, systematics, Orchidaceae, evolutionary ecology.
Immunological detection of an embryogenic-cell protein (ECP31) during stress-induced somatic embryogenesis in carrot
Authors: Kiyosue Tomohiro , Satoh Shinobu , Kamada Hiroshi , Harada Hiroshi
Published: December 2007

The accumulation and localization of ECP31, an embryogenic cell protein with a molecular weight of 31 000, was examined with immunoblotting and immunohistochemical analysis during stress-induced somatic embryogenesis in carrot (Daucus carota). ECP31 was not detected in apical tip segments of 7-day-old carrot seedlings. However, it accumulated in the apical tip segments on which somatic embryos had formed after treatment with 0.5 mM NiCl2 or CdCl2 and successive culture on Murashige and Skoog's agar medium without the heavy metal chlorides. ECP31 was localized in proembryo-forming cells located in the periphery of the NiCl2 treated carrot segments but not in developing somatic embryos on these segments. Key words: carrot (Daucus carota), ECP31 (carrot embryogenic cell protein with molecular weight 31 000), embryogenic competence, stress-induced somatic embryogenesis.
Distribution and prevalence of Fusarium subglutinans in mango trees affected by malformation
Authors: Ploetz R. C.
Published: December 2007

Infection of malformed and nonmalformed mango (Mangifera indica) trees by Fusarium subglutinans was assessed in Florida. All malformed floral panicles, but only 50% of the nonmalformed panicles, were infected by the fungus. When within-panicle infection was evaluated, an average of 84.5 % of the small pedicel and peduncle tissue pieces from malformed panicles were infected. When malformed and nonmalformed panicles were both assessed, 68.3% of the tissues from malformed panicles, but only 11.7% from nonmalformed panicles, were infected. Slight infection (2.2%) was observed in branch tissue that supported malformed panicles, and the fungus was never isolated from branches that supported nonmalformed panicles. In nutritional complementation tests with nitrate nonutilizing (nit) mutants, 55 of 64 isolates of F. subglutinans from malformed mango panicles were in the same vegetative compatibility group. The data indicate that mango malformation in the study area was significantly correlated (P < 0.0001) with infection by genetically related populations of F. subglutinans. The far greater prevalence of F. subglutinans in malformed than in asymptomatic panicles suggests that malformation symptoms develop in floral tissues only after they are extensively colonized by this fungus. Key words: Fusarium subglutinans, mango malformation, vegetative compatibility.
Life-history variation in the annual arable weed Diplotaxis erucoides (Cruciferae)
Authors: Sans F. X. , Masalles R. M.
Published: December 2007

Variation in life-history traits such as emergence, survival, time of flowering, and fecundity were studied in Diplotaxis erucoides, a mediterranean winter annual weed, by analyzing cohorts that emerged in autumn, early spring, and spring. The response of the plants to the environment, as reflected by plant architecture and pattern of biomass allocation, was also studied. Seedlings that germinate in autumn produced from 3 to 10 times more seeds than those that germinated in spring. The main factor affecting the number of seeds produced appears to be the life-span. Reduction of the growing period led to a decrease in both number and length of modular units, which resulted in decreased numbers of leaves, flowers, and fruits of each module. In semelparous D. erucoides plants, differences in the pattern of biomass allocation to reproduction are related to plant size. Our field data indicate that an increase of reproductive effort with size occurs in small individuals; however, a decrease occurs for vegetative biomass greater than 2 g and less than 5 g. Little variation in reproductive effort occurs when vegetative biomass is greater than 5 g. From a strategic point of view, size-dependent variation of reproductive effort in D. erucoides can be interpreted as good tactics to favour a higher proportion of resources devoted to reproduction in small individuals, thus ensuring some offspring. However, structural, developmental, and physiological constraints lead to stabilization or even a decrease in reproductive effort above a certain threshold size, when production of offspring is already ensured. Key words: phenotypic plasticity, plant architecture, biomass allocation, Diplotaxis erucoides.
Penicillium kananaskense, a new species from Alberta soil
Authors: Seifert Keith A. , Frisvad J. C. , McLean Mary Ann
Published: December 2007

The new species Penicillium kananaskense is described based on an isolate from soil in a Pinus contorta forest from Alberta, Canada. Colonies are characterized by their relatively rapid growth, velutinous texture, white to slightly pink conidial masses, growth at 5 °C, and absence of growth at 37 °C. The conidiophores are monoverticillate or have one metula, are up to 300 μm tall, smooth walled or with slightly roughened walls, vesiculate, and bear ampulliform phialides, 8–11.5(−14.5) × 2.5–4 μm, that produce disordered chains of ellipsoidal conidia, 3–5 × 2.5–4 μm, with smooth or finely roughened walls. The species is compared with previously described taxa and its subgeneric affinities are discussed. Preliminary data on the many secondary metabolites produced by the ex-type culture are presented. Key words: Penicillium kananaskense, soil, Pinus contorta var. latifolia, mycotoxins.
The rotated-lamina syndrome. IV. Relationships between rotation and symmetry in Magnolia and other cases
Authors: Charlton W. A.
Published: December 2007

Further variations of the rotated-lamina syndrome are described in Magnolia spp. and Rhamnus imeretinus, as well as an abnormal adult shoot of Ulmus glabra without lamina rotation. All magnolias investigated show lamina rotation, but there are four possible forms of shoot symmetry: (i) dorsiventral distichous shoots with the form of rotated-lamina syndrome previously described, i.e., laminae of young leaves all face towards the same (upper) side of the bud or towards the parental axis in axillary buds; (ii) another form of dorsiventral symmetry in which lamina rotation occurs in the reverse direction; (iii) spiral phyllotaxis with laminae rotated to face up the genetic spiral; and (iv) spiral phyllotaxis with laminae rotated to face down the genetic spiral. Shoot symmetry and development of lamina rotation in leaf primordia correlate with the taxo-nomic subdivision of the genus. Shoots of R. imeretinus are dorsiventral, with leaves arranged in four ranks, and lamina rotation occurs towards the upper side of the shoot. The sense of rotation of leaf primordia reverses with a periodicity of two plastochrons. In the abnormal shoot of Ulmus without lamina rotation, phyllotaxis was distichous and leaf primordia were symmetrical. The various cases are discussed in relation to the previously erected hypothesis that control of development in dorsiventral shoots with the rotated-lamina syndrome resides in alternating states of asymmetry in the shoot apex, and the corollary that a shoot with spiral phyllotaxis and one sense of lamina rotation should result if the state of asymmetry is maintained and does not alternate. Key words: Magnolia spp., Rhamnus imeretinus, Ulmus glabra, leaf, development, dorsiventrality, lamina rotation.
Regeneration of salal (Gaultheria shallon) in the central Coast Range forests of Oregon
Authors: Huffman David W. , Tappeiner II John C. , Zasada John C.
Published: December 2007

Regeneration of salal (Gaultheria shallon Pursh.) by seedling establishment and vegetative expansion was examined under various forest conditions in the central Coast Range of Oregon. Size and expansion rate of individual clonal fragments were negatively correlated with overstory stand density (p ≤ 0.039). As overstory basal area increased from 25 to 75 m2/ha, mean annual growth percentage of clone rhizome systems decreased from 23.7 to 0.0% and mean total rhizome length decreased from 102 to 0.89 m. Interclonal competition in dense clumps of salal apparently causes rhizomes to die and clones to fragment. In these patches, rhizome biomass and density, aerial stem biomass and density, and total biomass were negatively correlated with overstory density (p ≤ 0.01). For example, in clearcuts, salal clumps had up to 177.7 m rhizome/m2 and 346 stems/m2, whereas patches under dense overstories had as few as 10.6 m rhizome/m2 and 19 stems/m2. Aerial stem populations had uneven-age distributions of aerial stems in all overstory conditions. This structure is apparently maintained through annual production of new ramets. Salal seedling establishment rates were significantly affected by study site location, overstory density, and substrate (p ≤ 0.05). Two-year survival was highest on rotten logs and stumps in thinned stands. Key words: clonal morphology, clone populations, Douglas-fir forests, Gaultheria shallon, seedling establishment, vegetative expansion.