bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoperiodic adaptation of Xanthium strumarium in Europe, Asia Minor, and northern Africa
Authors: McMillan Calvin
Published: September 2008

The range of photoperiodic adaptation among populations of Xanthium strumarium L. in Europe, Asia Minor, and northern Africa is nearly as broad as among populations in North America. Photoperiodic diversity within the indigenous morphological complex, strumarium, is relatively restricted, including night requirements primarily less than 8 h. American introductions include plants with reproductive requirements ranging from 7.5-h nights in northern populations to 10.5–11-h nights in southern populations. Populations in northern Europe in indigenous strumarium and introduced complexes, echinatum and italicum, show a photoperiodic response thinly separated from day neutrality. Southern European populations show reproductive diversity among introduced plants and include sympatric occurrences of three morphological complexes, cavanillesii of South America, chinense of North America, and orientale possibly of North America. The chinense introductions to northern Africa (Morocco, Egypt) are similar to those of Spain with a night requirement of 10.25–10.5 h. Those of Asia Minor include the italicum complex in Turkey and Israel, 9.0–9.25 h, and the chinense complex in southern U.S.S.R., 9.75 h, and in Israel and Iraq, 10.5–11.0 h. Although some of the photoperiodic diversity of the cockleburs of the Old World probably resulted from hybridization between indigenous and introduced plants, the broad adaptive potential was imported from America.
Reproductive dynamics of four plant communities of southwestern British Columbia
Authors: Pojar Jim
Published: September 2008

A study of angiosperm reproductive biology was made in four plant communities in southwestern British Columbia. Species of all four communities have staggered, peak flowering times, resulting in phenological spectra. Anemophily is the major mode of pollination in a salt marsh, while entomophily predominates in a subalpine meadow. Two sphagnum bogs have more of a balance between wind and insect pollination. There are corresponding differences in the proportions of showy-flowered species in the communities. It is proposed that interspecific competition has greatly influenced the evolution of both species and community flowering strategies.Biotic seed dispersal prevails in the salt marsh and bogs, while most of the subalpine meadow species are wind-dispersed. Species and community modes of dispersal depend on the nature of the vegetation and the relative availability of dispersal vectors, as well as on diaspore morphology.Although vegetative reproduction and self-compatibility are fairly common, the bulk of the flora and vegetation at all four sites has breeding systems promoting outcrossing. There is little evidence that the physical environments of these communities, all harsh in at least some respects, have selectively favored autogamous or agamospermous species.
Light- and ultra-microscopical observations on the surface structure of the protoplasmodium, aphanoplasmodium, and phaneroplasmodium (Myxomycetes)
Authors: Haskins Edward F. , Hinchee A. Arlan
Published: September 2008

The surface structure of three types of myxomycete Plasmodia, namely, protoplasmodium (Echinostelium minutum), aphanoplasmodium (Stemonitis flavogenita), and phaneroplasmodium (Physarum polycephalum), was studied with light, scanning, and transmission electron microscopy. E. minutum and P. polycephalum possess robust slime sheaths composed of filaments 50–100 Å in diameter. The hyaline aphanoplasmodium of S. flavogenita lacks a slime sheath; its plasmodial surface is covered with slender filopodia. The potential role of the plasmodial surface is discussed in relation to phagocytosis, cell movement, coalescence, and cell wall formation.
Tremella globospora, in the field and in culture
Authors: Brough Sherman G.
Published: September 2008

Tremella globospora Reid is described from 32 collections made in British Columbia. The fungus grows directly from within perithecia of species of Valsa and Diaporthe found, in this study, on hosts belonging to seven Angiosperm genera and three of Gymnosperm. Single-spore isolates were made from basidiocarps selected to represent as many variables as possible; both colors (yellow and white) of the basidiocarp, proximity of position on a single twig versus considerable distance between sites, both genera of pyrenomycete host, four genera of seed plants, and collection dates from January to September. Compatibility tests indicated a single species with a modified tetrapolar mating system typical of the genus Tremella. Selected dikaryotic isolates were grown in laboratory culture on simple media, and fertile basidiocarps were produced. Variation in size, color, and consistency of basidiocarps in culture was compared with those in field collections. Clamp connections, branching from the clamp cell, and other microstructures produced in culture are also described. No reaction of T. globospora to Valsa cultures or sterilized Valsa perithecia and extracts was observed.
Déficience en biotine et perméabilité cellulaire d'Hypomyces chlorinus
Authors: Nomdedeu Louis , Sancholle Michel , Touzé-Soulet Jane-Marie
Published: September 2008

not available
Distinctions between Hirschioporus subchartaceus and H. pargamenus
Authors: Traquair James A. , Kennedy Lorene L.
Published: September 2008

Genetical and developmental studies support the conclusion that Hirschioporus pargamenus (Fr.) Bond. & Sing. and H. subchartaceus (Murr.) Bond. & Sing. are distinct but closely related species. Paired monokaryotic isolates from each species were almost completely intersterile and produced lines of demarcation containing peculiar clasping hyphae. Distinctions were found in basidiospore size and in the macrostructure and microstructure of the margin, context, upper surface, and hymenial surface of natural basidiocarps. In culture, clear distinctions were observed in hymenial configuration of basidiocarps and spore size.
Essai de croisements experimentaux entre taxa alliés au Plantago maritima d'origines diverses
Authors: Marcotte J. L.
Published: September 2008

Seeing that it was impossible to identify with any precise taxon the icelandic plantains related to Plantago maritima L., the author has tried to solve this problem with the help of experimental crosses. The results have shown that icelandic plantains, though not genetically isolated, are on the verge of becoming so. Genetic isolation is becoming progressively stronger, owing to geographic isolation. [Traduit par le journal]
The spores of Dryopteris filix-mas and related taxa in North America
Authors: Britton D. M. , Jermy A. C.
Published: September 2008

Scanning electron micrographs of spores of Dryopteris filix-mas (L.) Schott, D. abbreviata (DC.) Newman, D. caucasica Fraser-Jenkins & Corley, D. arguta (Kaulf.) Watt, D. marginalis (L.) Gray, and D. fragrans (L.) Schott var. remotiuscula Komarov are presented. North American D. filix-mas is compared with the European species and the origin of this tetraploid is discussed using the available evidence from spore morphology, cytogenetics, and chromatography.
Studies on lichen-dominated systems. X. The sedge meadows of the coastal raised beaches
Authors: Kershaw K. A.
Published: September 2008

The relationship of the sedge meadows lying between raised-beach ridges at the Pen Island site in NW Ontario is described using principal-component analysis. Three major trends are detected following moss hummock formation, depth of water table, and pH. The data also show a progressive sequence from the young meadows with few hummocks and high pH to the older meadows where marked hummock formation has occurred and where the overall pH is lower. Six noda have subsequently been extracted as the central plant associations characteristic of the area.
A scanning electron microscope study of the spores and selected peristomes of the North American Encalyptaceae (Musci)
Authors: Vitt Dale H. , Hamilton Catherine D.
Published: September 2008

The eight North American species of Encalypta can be readily distinguished on the basis of spore morphology as viewed in the scanning electron microscope. Descriptions are given of the spores of each species as well as those of Bryobrittonia pellucida. Although the spores of Bryobrittonia closely resemble those of Encalypta procera, Bryobrittonia is easily distinguished from all Encalypta species in having mammillose leaf cells. Based on spore polarity and ornamentation, Encalypta can be divided into three groups, these closely approximating groupings that have been proposed on the basis of peristome characteristics. Of the three peristomes examined, that of E. longicolla appears to consist of whole cells, that of E. brevicolla of both whole cells and cell walls, while the peristome of E. rhaptocarpa consists of cell walls only.
In vitro induction of embryoids in tissue cultures of Nigella damascena
Authors: Raman K. , Greyson R. I.
Published: September 2008

Callus derived from the pedicels and floral buds of Nigella damascena L. when broken down to single cells and small clumps produced large numbers of embryoids. These embryoids passed through stages comparable to zygotic embryogeny in a defined nutrient medium.
Notes on Hyphomycetes. VI. Concerning two species of Dendryphiopsis
Authors: Morgan-Jones G.
Published: September 2008

Dendryphiopsis arbuscula (Berk. and Curt.) Hughes and D. fascicularis (Berk. and Rav.) Hughes are redescribed and illustrated.
Lophodermium pinastri: certain fine-structural features of ascocarp morphology
Authors: Silverberg B. A. , Morgan-Jones J. F.
Published: September 2008

As viewed by the electron microscope, the 'carbonaceous' appearance of the ascocarp clypeus in Lophodermium pinastri (Schrad) Chev. is due to a dark substance in the interhyphal spaces; this substance is believed to originate within the hyphae since the latter contain dark inclusions of the same electron density. The mucilaginous material in the ascocarp cavity is primarily in the nature of an acid mucopolysaccharide, together with minimal amounts of carbohydrates and proteins. Examination of the interthecial hyphae by means of scanning electron microscopy (SEM) shows them to be true paraphyses, not pseudoparaphyses as previously supposed.
Contribution à la tératologie des Chèvrefeuilles et au problème des fusions. II. La concaulescence
Authors: Lamond M. , Vieth J.
Published: September 2008

This paper is mainly concerned with the anatomical and morphological features of over 15 teratological samples of honeysuckle showing diverse types of "concaulescence."Most frequently, "concaulescence" is the only abnormality present and three different morphological–anatomical types of adnation may be distinguished. (1) The adnated sprigs (hypopodia) are attached to the main axis by a narrow strip of cortex; both the sprig gap and the seriated buds are located at their usual level. (2) The vascular bundles of the adnated axes separate themselves progressively, and frequently there is no seriated bud at the axil of the adnated sprigs. (3) The lateral sprigs remain closely fused with the main axis until they free themselves abruptly and then the seriated buds appear at the free axil.Studies of the other samples are complicated by the occurrence of some phyllotaxic anomalies below the adnation area. Among these anomalies the most frequent are (1) the vertical displacement between the opposite petiole insertion area of the node and (2) the stretching of the foliar bases and the accompanying sessile leaves at this abnormal node.
Photosynthetic activity of cotyledons and foliage leaves of young angiosperm seedlings
Authors: Marshall P. E. , Kozlowski T. T.
Published: September 2008

Absorption of 14CO2 and distribution of 14C-photosynthate from cotyledons and foliage leaves were studied for 35 days after seed germination in Acer rubrum, Robinia pseudoacacia, and Ulmus americana seedlings. Differences occurred among species in total carbohydrate requirements, strengths of various carbohydrate sinks, and importance of cotyledons or foliage leaves as sources of carbohydrates. Robinia cotyledons fixed appreciable 14C 2 to 4 days after seedling emergence. Acer and Ulmus cotyledons fixed only small amounts of 14C 2 days after seedling emergence, but a significant increase in fixation occurred 4–6 days after seedling emergence. Photosynthesis in very young cotyledons was inhibited more by lack of stomata than by a deficiency of chlorophyll. As cotyledons reached maximum size, and as other plant parts were rapidly expanding, the cotyledons retained less 14C-photosynthate, and a higher proportion of label was translocated basipetally to the stem and roots and acropetally to the stem and leaves. Compared with cotyledons, young hypocotyls fixed small quantities of 14C and insignificant 14C was fixed by stems 10 days after seedling emergence. Fully expanded foliage leaves accounted for an increasingly larger percentage of total 14C fixation, and eventually more label was exported from leaves than from cotyledons. In 10- to 15-day-old plants much more 14C was fixed by cotyledons of young Robinia plants than by cotyledons of Acer or Ulmus. This difference was largely the result of more cotyledon tissue in Robinia rather than in more efficient photosynthesis per unit of cotyledon tissue.
Isoelectric focusing of peroxidases released from soybean hypocotyl cell walls by Sclerotium rolfsii culture filtrate
Authors: Curtis C. R. , Barnett Neal M.
Published: September 2008

Bound soybean hypocotyl cell wall proteins can be released from the cell wall by incubation with a culture filtrate of the fungal pathogen Sclerotium rolfsii. The released cell wall proteins were then separated by disc electrophoresis or isoelectric-focusing techniques in polyacrylamide gel columns and tested for peroxidase and esterase activity. Released cell wall proteins showed considerable peroxidase multiplicity, which was totally absent in the separation of fungal culture filtrate. Peroxidase patterns of some released cell wall peroxidases were similar to soybean cytoplasmic peroxidase patterns. In separate experiments, esterase bands were detected in the released cell wall proteins, but this was probably due to esterase activity of the fungal culture filtrate. Cytoplasmic esterases exhibited much higher isoelectric points than cell wall and culture filtrate esterases, which were concentrated between pH 3 and 6.
Biosynthesis of phenolic acids in tomato plants infected with Agrobacterium tumefaciens
Authors: Chadha Kailash C. , Brown Stewart A.
Published: September 2008

Tomato plants 21 days old were inoculated with Agrobacterium tumefaciens, the causative organism of crown gall, and 72 h later [3-14C]cinnamic or [carboxyl-14C]benzoic acid was administered by wick-feeding to these and to uninfected control plants. After a further 48 h both groups were examined for incorporation of label into phenolic acids. The pattern of incorporation into bound phenolic acids of the controls was in accord with biosynthetic pathways previously demonstrated in normal plants, but qualitative and quantitative divergence from this pattern was observed in the bound phenolic acids of the infected plants. The data suggest interference by the pathogen with β-oxidation of at least two phenylpropanoid acids of the lignification pathway. In infected plants, lowered incorporation of 14C from cinnamic acid into phenylpropanoid acids of the lignification pathway and their β-oxidation products was accompanied by the appearance of labelled o-coumaric acid, consistent with some diversion of cinnamic acid metabolism toward ortho-hydroxylation. Incorporation of 14C from benzoic acid into gentisic and especially salicylic acid of infected plants was much lower than in the controls.
Cytology of somatic and gametangial nuclei in Phytophthora capsici and Phytophthora megasperma var. sojae
Authors: Stephenson L. W. , Erwin D. C. , Leary J. V.
Published: September 2008

Nuclear divisions in the hyphae and gametangia of Phytophthora capsici and in hyphae of Phytophthora megasperma var. sojae resembled those of typical mitosis. The chromosomal configurations in prophase are similar to classical angiosperm prophase configurations. However, in metaphase the linear alignment of chromosomes resembled the pattern reported in pollen tubes of Lilium and Tradescantia. The relative size of nuclei and numbers of chromosomes per nucleus remained constant during gametangial development. Somatic and gametangial nuclei were about equal in size and chromosome number. Chromosome numbers in somatic and gametangial nuclei of P. capsici and P. megasperma var. sojae were about six and eight, respectively. There was no evidence of reduction division in gametangia.
Didymella festucae and its imperfect state, Phleospora idahoensis, on Festuca species in western North America
Authors: Smith J. Drew , Shoemaker R. A.
Published: September 2008

Didymella festucae (Weg.) Holm (imperfect state Phleospora idahoensis Sprague), endemic on native Festuca spp. in western North America and reported from a few arctic–alpine regions in Europe, is the cause of a major destructive stem eyespot disease in seed crops of red fescue, Festuca rubra L., in the Peace River region of northern Alberta and British Columbia. The original description of the disease as a leaf and pedicel blight requires modification because eyespots, staining, and later extensive blackening of culms and inflorescences are the common symptoms. The size range of ascospores, 18–63 × 4.5–14.0 microns (μ), and conidia, 18–105 × 3.0–9.0 μ, considerably exceeded dimensions previously given for D. festucae from Europe and P. idahoensis from North America and Europe. Although the morphology of fungal structures was highly variable, dimensions of ascospores and conidia from the Swiss type material fell into the size range established for North American material. Swiss type material of the perfect stage also yielded typical conidia of P. idahoensis. Microconidia are uncommon in natural material and cultures and their function is uncertain. Pathogenicity tests confirmed the wide natural-host range. Host immunity or physiologic specialization of the fungus is not indicated, but there is some evidence that isolates differ in degree of pathogenicity. For the present, P. idahoensis is suitably accommodated in Phleospora and D. festucae in Didymella, although both genera are ill-defined, requiring further study.
Cone initiation and development before dormancy in yellow cedar (Chamaecyparis nootkatensis)
Authors: Owens John N. , Molder Marje
Published: September 2008

Vegetative shoots initiate leaves and lateral branches continuously from mid-April until the end of September. No buds with bud scales are formed and the vegetative apex is enclosed by leaf primordia at various stages of development. Pollen cones are initiated on proximal vegetative shoots during a 3-week period from mid-June to early in July. Transition to a pollen-cone apex is marked by an increase in mitotic activity in the apex and by the formation of a lateral branch in the axil of one of the last-formed leaf primordia, causing the apex to appear to branch dichotomously. The lateral branch remains at the base of the pollen cone and may resume growth the next year after the pollen cone is shed. Pollen-cone development continues until the end of September. Meiosis occurs during the last 2 weeks of August, and pollen develops during September. Seed cones are initiated on newly formed, distal axillary vegetative shoots during a 3-week period from late June to mid-July. Transition to a seed-cone apex is marked by an increase in mitotic activity followed by bract-scale initiation. Usually three ovules are initiated in the axil of each bract scale. Seed-cone development is complete by early September and the seed cones become dormant. The pattern of reproduction in yellow cedar is compared to other conifers and the possible relationships are discussed between time of cone initiation, sexuality of cones, and day length.
Ethylene and carbohydrate requirements for apogamous bud induction in Pteridium gametophytes
Authors: Elmore H. W. , Whittier D. P.
Published: September 2008

Periodic evacuations of culture vessels containing Pteridium gametophytes to reduce the concentration of endogenous ethylene within the tissue, followed by reinfiltration with air, yielded a 99% reduction in apogamous budding as compared to the ethylene-reinfiltrated control. Growing gametophytes in increasing concentrations of carbon dioxide, a competitive inhibitor of ethylene, caused decreases in the apogamous response. Apogamy was completely eliminated by 7% carbon dioxide, without inhibiting gametophytic growth. Adding 1 μl/liter ethylene to each concentration of carbon dioxide reversed the inhibition and some apogamy did occur in gametophytes grown in 7% carbon dioxide supplied concomitantly with the exogenous ethylene. A carbohydrate is required for ethylene-induced apogamous bud induction. Growth of gametophytes in the presence of ethylene on medium lacking sucrose for extended experimental periods was not sufficient to cause induction. Total gametophytic growth on media containing various concentrations of sucrose was not affected by the presence or absence of ethylene in the atmosphere surrounding colonies. These results demonstrate that both ethylene and a utilizable carbohydrate are required for apogamy.
Secondarily homothallic Hymenomycetes: several examples of bipolarity are reinterpreted as being tetrapolar
Authors: Ginns James H.
Published: September 2008

The pairing tables for five species of secondarily homothallic Hymenomycetes, Agaricus bisporus (Lange) Imbach, Aleurodiscus canadensis Skolko, Conocybe pubescens (Gill.) Kühner, Coprinus sassii M. Lange & Smith, and Poria vincta var. cinerea (Bres.) Setliff were reorganized and reinterpreted. The fungi are apparently secondarily homothallic tetrapolar, not bipolar or secondarily homothallic bipolar as originally reported.
The formation of branching strands at the apex of radicles of Arceuthobium pusillum cultured in vitro
Authors: Bonga J. M.
Published: September 2008

The obligate parasite eastern dwarf mistletoe cultured on a modified White's medium produced thin, branching strands at the apex of the radicles. These strands were similar to young cortical strands in vivo.
Etude ultrastructurale et cytochimique de l'appareil sporifère chez Phialophora richardsiae
Authors: Olah G. M. , Reisinger O.
Published: September 2008

The observation with the electron microscope of specimens during conidium initiation reveals the enteroblastic nature of the conidial prefiguration. The morphological characteristics expressed during the other stages of conidiogenesis (conidium maturation and propagule liberation) are also studied. The cytochemical techniques (showing the presence of polysaccharidic and proteinic substances) confirm our conclusions on the nature of the newly formed primary sporal envelope and show an identical wall structure whatever the organ studied.A comparison with the functioning of other types of phialides is made and a relationship between the phialoconidiogenesis (Phialophora richardsiae (Nannf.) Conant.) and the annello-conidiogenesis (Doratomyces purpureofuscus), based on the similarity of conidium initiation mechanisms, is accepted.
The influence of light and diurnal freezing temperature on the cold hardiness of winter wheat seedlings
Authors: Andrews C. J. , Pomeroy M. K. , Roche I. A. de la
Published: September 2008

Seedlings of winter wheat (Triticum aestivwn cv. Rideau and Cappelle Desprez) grown on moist filter paper in petri plates in dark at low temperature increased in cold hardiness, as measured by changes in the LD50 temperatures. Rideau attained an LD50 temperature of −12 °C after 5 weeks, Cappelle Desprez, −6 °C. Exposure to light delayed the maximum hardiness by 2 weeks and increased it by 6 °C in both cultivars. Exposure to diurnal freezing temperature increased hardiness of both cultivars in the dark, and in light when excessive dehydration was prevented.Greater cold hardiness of plants of both cultivars was attained in soil in light at low temperature as compared with those in petri plates. Exposure of plants to diurnal freezing temperature maintained a higher level of hardiness after the maximum at 7 weeks than continuous low temperature without freezing. Diurnal freezing during active low temperature growth in petri plates or in soil increased hardiness of Rideau seedlings to an apparent maximum of −18 °C.
Photosynthesis and photorespiration during the ontogeny of the bean plant
Authors: Fraser D. E. , Bidwell R. G. S.
Published: September 2008

Ontogenetic changes in true photosynthesis, apparent photosynthesis, and photorespiration were measured in the individual leaves of bean plants throughout the development of the plant to flowering. The relationship between true photosynthesis and photorespiration (termed assimilation efficiency) was determined. Leaf resistances were also measured, and the relationships of photosynthesis and photorespiration to mesophyll resistance (rm) and stomatal resistance (rs) were determined.There is an intrinsic ontogenetic pattern of gas exchange for each leaf, but this is modified by events that take place during development in other parts of the plant such as subsequent leaf emergence or flowering. Photosynthesis and photorespiration appear to be affected by the requirement for export of assimilates, but the two processes vary independently. Photosynthesis is regulated by rm and is weakly regulated by rs as well. However, photorespiratory CO2 release is not related either to rm or to rs under the conditions of these experiments. These results emphasize the importance of the precise control and description of experimental material in the analysis of gas exchange in leaves.
Concerning some species of Microsphaeropsis
Authors: Morgan-Jones G.
Published: September 2008

Microsphaeropsis centaureae sp. nov., isolated from Centaurea diffusa Lam. in British Columbia, is described and illustrated. Its pathogenicity to both C. diffusa and C. maculosa Lam. is noted. It is compared with Microsphaeropsis olivacea (Bon.) Höhnel and with Coniothyrium concentricum (Desm.) Sacc, C. onychiuri Punithalingam, and C. sarcinellae Sahni. The latter species are transferred to Microsphaeropsis.
Benzyladenine accelerates chloroplast differentiation and stimulates photosynthetic enzyme activity in cucumber cotyledons
Authors: Harvey B. M. R. , Lu B. C. , Fletcher R. A.
Published: September 2008

The chloroplasts of etiolated cucumber cotyledons had crystalline prolamellar bodies, whereas those treated with benzyladenine (BA) have a well-developed plastid membrane system. After 4 h of exposure to light, grana were formed in the chloroplasts of BA-treated cotyledons but not in the controls. The specific activities of ribulose 1,5-diphosphate carboxylase, and NADP-dependent glyceraldehyde 3-phosphate dehydrogenase increased 75 and 50% respectively during BA treatment in the dark, while there was little change in the controls. On exposure to light, enzyme activities increased in both control and BA-treated cotyledons. Inhibitors of protein synthesis eliminated the BA stimulation of ribulose diphosphate carboxylase but had little effect on the BA stimulation of NADP-dependent glyceraldehyde 3-phosphate dehydrogenase activity. This study indicates that BA stimulates structural differentiation of the chloroplast and enhances activities of photosynthetic enzymes, even in the dark.
Chloroplast ultrastructure and ethylene production of senescing and rust-infected cowpea leaves
Authors: Heath Michèle C.
Published: September 2008

An investigation of the changes in chloroplast ultrastructure induced by rust infection of cowpea leaves revealed that although initial changes in the pustule center resembled those observed in naturally senescing leaves, subsequent changes more closely resembled chromoplast development in certain ripening fruit. Ethylene treatment of healthy leaves induced changes similar to those seen during the later stages of pathogenesis and detached infected leaves released greater amounts of this gas than controls. The restriction of the chromoplast-like changes to the pustule center and the fact that the endogenous ethylene levels of newly picked infected leaves were barely higher than those of comparable healthy tissue suggested that most of the increased production of this gas was associated with the relatively small region of high fungal concentration. In contrast, naturally senescing leaves contained one-sixth, or less, of the ethylene content of infected leaves and released about half as much as infected tissue when detached. Thus it is suggested that, in many plants, increased ethylene production results in chromoplast-like development of the chloroplasts and that the degree of such development during pathogenesis or senescence may reflect the degree of ethylene production during these processes.
Nitrate metabolism in relation to the aspartate-type C-4 pathway of photosynthesis in Eleusine coracana
Authors: Rathnam C. K. M. , Das V. S. R.
Published: September 2008

The intercellular and intracellular distributions of nitrate assimilating enzymes were studied. Nitrate reductase was found to be localized on the chloroplast envelope membranes. The chloroplastic NADPH – glutamate dehydrogenase was concentrated in the mesophyll cells. The extrachloroplastic NADH – glutamate dehydrogenase was localized in the bundle sheath cells. Glutamate synthesized in the mesophyll chloroplasts was interpreted to be utilized exclusively in the synthesis of aspartate, while in the bundle sheath cells it was thought to be consumed in other cellular metabolic processes. Based on the results, a scheme is proposed to account for the nitrate metabolism in the leaves of Eleusine coracana Gaertn. in relation to its aspartate-type C-4 pathway of photosynthesis.
Isoenzymes in cell cultures of bush bean (Phaseolus vulgaris cv. Contender): isoenzymatic changes during the callus culture cycle and differences between stock cultures
Authors: Arnison Paul G. , Boll W. G.
Published: September 2008

Electrophoretic analyses of isoenzyme patterns were performed with extracts of root, hypocotyl, and cotyledon callus cultures derived from a single seedling. The enzymes studied included peroxidase, polyphenol oxidase, catalase, malate and glutamate dehydrogenases, esterase, and leucine amino peptidase. Enzyme patterns changed during the culture cycle and several isoenzymes appeared only at certain times. The isoenzymatic patterns of the three cultures were very similar but persistent differences between them were observed.
Notes on Hyphomycetes. VII. An addition to the genus Phaeoisariopsis
Authors: Morgan-Jones G.
Published: September 2008

Cercospora gnaphaliaceae Cooke is redescribed, illustrated, and reclassified in Phaeoisariopsis Ferraris. Cercospora gnaphalii Harkness is considered to be conspecific with it.
A first record of Sclerotinia sclerotiorum and Microsphaeropsis centaureae on Centaurea diffusa
Authors: Watson A. K. , Copeman R. J. , Renney A. J.
Published: September 2008

Sclerotinia sclerotiorum (Lib.) de Bary and Microsphaeropsis centaureae Morgan-Jones were isolated from Centaurea diffusa Lam. The pathogenicity of both fungi to C. diffusa and C. maculosa Lam. is noted.
Basidiospore production and infection of balsam fir by a needle rust, Pucciniastrum goeppertianum
Authors: Sickle G. A. Van
Published: September 2008

Basidiospores of Pucciniastrum goeppertianum (Kühn) Kleb. are globose, 5.8 μ in diameter, smooth-walled, apiculate, and have granular contents. The cardinal temperatures for their discharge were found to be 10, 18 to 20, and 25 °C. Development of new brooms from infected blueberry rhizomes started late in May, but shoots tested monthly in the laboratory released spores only from the next January until mid-June. The natural overwintering requirements of the fungus were mimicked by storing broom material at −4 °C from December until February.On balsam fir needles at 15 °C, germination of basidiospores usually produced a single, short germ tube, and exceeded 40% after 7 h of saturation and reached 70% by 48 h. Repetitive germination, commonly seen on glass slides or water agar, may only be typical of the reaction on non-host substrates. Only current-year needles were susceptible to infection and only from bud break until early in the 5th week, (corresponding approximately to the period of shoot elongation) provided that a minimum of 6 h at 15 °C under conditions of saturation preceded any period of drying of the foliage surface.
The effect of photoperiod and temperature on northern Canadian ecotypes of Agropyron trachycaulum var. trachycaulum (slender wheatgrass)
Authors: Pringle W. L. , Elliott C. R. , Degenhardt K. J.
Published: September 2008

Thirty-five plants of Agropyron trachycaulum from northern Canada were categorized as to the latitude of origin. Categories were 53–55, 55–58, 58–61, and 61–68° north latitude. In field plots at Beaverlodge (latitude 55° N) the plants originating from farthest north had the shortest number of days from heading to maturity and lowest average height and seed yield. Controlled environment studies confirmed that plants from north of 60° latitude have reduced capability of producing seed culms in summer environments with less than continuous light. Seed production of such species would be suspect in the current farming areas at lower latitudes. If large quantities of seed were required, new seed production areas may have to be developed in northern latitudes.
A pollen diagram from a postglacial peat bog in Hants County, Nova Scotia
Authors: Hadden Kathleen A.
Published: September 2008

The pollen stratigraphy of a 6.7-m section of bog peat from west–central Nova Scotia shows three major pollen zones, viz., the zone of spruce maximum (9180–8505 before present (BP)); the zone of pine and oak maxima (8505–6290 BP); and the upper deciduous zone, which could be more accurately described as the bimodal hemlock zone (6290 BP to present day). The zone of hemlock minimum is dated at 4415 BP. The spruce assemblage denotes a cool, wet climate. The decrease in spruce and increases to maxima of pine and oak are interpreted in terms of higher temperatures and lower precipitation. Further temperature increase, perhaps accompanied by increased precipitation, resulted in the migration of hemlock into the area subsequently suppressed during the period of maximum warmth and dryness. Increased precipitation followed by decreased temperatures led firstly to a second hemlock stage and later to increased coniferous growth. Increased representation of grasses and adventives in the upper levels of the assemblage are indicative of European colonization.
Ion uptake by rhizomorphs of Armillaria mellea
Authors: Morrison D. J.
Published: September 2008

Rhizomorphs of Armillaria mellea (Vahl ex Fr.) Kummer absorbed ammonium and radio-actively labelled chloride and orthophosphate ions; ammonium uptake was associated with synthesis of amino acids in the rhizomorphs. Uptake of labelled ions occurred primarily at the unpigmented growing tip. Nutrient uptake by rhizomorphs may explain why the dry weight of rhizomorphs is related to the nutrient status of the soil in which they are growing.
Hypoxylon serpens: cytology and taxonomic considerations
Authors: Rogers Jack D.
Published: September 2008

The haploid chromosome number of Hypoxylon serpens is seven. Ascospores are initially uninucleate, becoming binucleate after a mitosis. One nucleus is cut off in a cellular appendage which degenerates before ascospores become colored. Mature ascospores are uninucleate and devoid of appendages. Taxonomic implications of these data are discussed.
The effects of drought on water relations and stem shrinkage of Quercus alba
Authors: Hinckley Thomas M. , Bruckerhoff David N.
Published: September 2008

Stem circumference, xylem pressure potential (P), and leaf surface resistance were measured in a dominant forest-grown white oak (Quercus alba L.) tree from the beginning of, through the development of, and to recovery from a major drought in mid-Missouri. Continuous recording of several environmental variables and periodic measurements of soil moisture were made in coordination with the above plant variables. As base P(P measured just before sunrise) and soil moisture decreased, net day-to-day and even week-to-week stem shrinkage was observed. Periodic thunderstorms alleviated soil and plant water deficits and stem circumference recovered. Excellent relationships were noted between soil moisture in the upper 30 cm of a 107-cm profile and either base P or stem circumference.Four clear and 2 cloudy days with rain are presented to illustrate diurnal patterns in the aforementioned variables. The generalized pattern of diurnal fluctuations in stem circumference consisted of early morning shrinkage, which continued to a 1500- to 1700-h. (true solar time) minimum, and subsequent recovery. Hysteresis loops resulted when stem circumference was plotted against P. Maximum diurnal fluctuations in stem circumference were greatest when soil moisture had been depleted slightly below field capacity. Further depletion led to lower values of P, stomatal closure, restricted plant water loss, and reduced stem shrinkage. The relationship between flux (vapor pressure deficit – leaf surface resistance) and P is also described and it provided a possible means of modeling P in plants. The possible role of the stem reservoir in augmenting foliar water deficits is presented and discussed.
Growth of Tremella mesenterica haplonts with various nitrogen sources
Authors: Reid Ian D.
Published: September 2008

Haplonts of the fungus Tremella mesenterica grew in synthetic media containing any of the following nitrogen sources (in order of decreasing growth rate): glutamine, aspartate, leucine, glutamate, alanine, ammonium sulfate, serine, soytone, casein hydrolysate, phenylalanine, and asparagine. Cultures with potassium nitrate, cysteine, glycine, histidine, lysine, or proline as sole N source did not grow. Thiamine was the only vitamin required. Asparagine slowed the growth of some strains and also caused the cells to become large and spherical.
Influence of pollen on germination of conidia of Claviceps purpurea
Authors: Williams Jill R. , Colotelo Nicholas
Published: September 2008

The in vitro effect of rye, wheat, rape, and tobacco pollen on germination of conidia of Claviceps purpurea was studied at a number of pollen concentrations. Pollen and spore suspensions were incubated together for 24 h before pollen effect was assessed. All pollen stimulated germination of conidia, with rye pollen causing the greatest increase. Wheat pollen had a similar stimulatory effect to rye pollen at comparable concentrations. Rape pollen caused similar stimulation at high concentrations, but less of an effect at low concentrations. Tobacco pollen was less effective than rye pollen at all concentrations. Pollen from host and non-host species was shown to stimulate germination, but the greatest effect was always caused by pollen from the natural host, rye.
Ecology of Endogone in Lake Huron sand dunes
Authors: Koske R. E. , Sutton J. C. , Sheppard B. R.
Published: September 2008

Grasses and herbs in the sand dunes of the eastern shores of Lake Huron were heavily colonized by the endomycorrhizal fungus Endogone. The fungus produced an extensive external mycelium in the dune sand. Numerous sand grains were firmly bound to the external mycelium, which was of structural importance in sand aggregates and was implicated as an important factor in dune stabilization. Sand aggregates constituted about 5 to 9% of the dry weight of sand collected from the surface 30 cm of the dunes. The weight of sand aggregates per kilogram of dune sand increased from 0.9 g to 25 g and 127 g after one and two crops, respectively, of mycorrhizal Phaseolus vulgaris L. grown in pots in a controlled environment. The increased aggregation was attributed largely to the binding of sand grains to a proliferated mycelium of Endogone. Organic fragments in the dune sand were colonized frequently by Endogone. Spores and spore-like bodies were numerous in many organic particles, which were sources of viable inoculum of Endogone. Five types of Endogone spores were found in the dune sand.
The ultrastructure of the moss Tortula ruralis on recovery from desiccation
Authors: Tucker E. B. , Costerton J. W. , Bewley J. D.
Published: September 2008

The papillose cells of T. ruralis are composed of cytoplasm containing a nucleus, four or five chloroplasts, mitochondria, endoplasmic reticulum, golgi bodies, electron-dense cytoplasmic bodies, and many small vesicles. Their adaxial and abaxial cell walls are composed of two fibrous layers and a cuticle, from which filamentous threads arise. These cells are interconnected by membrane-lined plasmodesmata.Dehydration causes condensation of the protoplasm at the distal and proximal cell ends, rounding and compacting of the chloroplasts, and vesicle disappearance. Immediately upon rehydration the chloroplasts and mitochondria swell and their internal membrane structures are rearranged. However, during a 24-h rehydrating period the cell structure returns to that of the normal hydrated state.
Vessel blockage by myelin forms in citrus with and without rough-lemon decline symptoms
Authors: Nemec S.
Published: September 2008

Vessels in xylem of citrus trees with wilt symptoms described as rough-lemon, sandhill, and young-tree decline, or blight, were often found plugged, generally at constrictions of vessel ends. Diseased trees had significantly more vessels plugged than healthy trees. The plugging substance was composed of a dense network of cylindrical strands, with a diameter of about 0.3 μm, which were identified as myelin forms. Electron microscopy revealed that these strands were composed of concentric bands of electron-dense material of varying intensity. These strands stained blue-black with Sudan black B and light green with Nile blue sulfate and were positive for unsaturated lipids with osmium. They reacted positively for phospholipid with orange G – aniline blue, and choline was detected by the acid haematin test. The myelin forms originated from accumulations of lipid on the inside walls of vessels that formed by migration of lipid through vessel pits from adjacent parenchyma cells. Large quantities of lipid bodies formed in ray parenchyma, and lipid-like bodies were observed in phloem cells.
Effect of naphthalene and aqueous crude oil extracts on the green flagellate Chlamydomonas angulosa. I. Growth
Authors: Soto C. , Hellebust J. A. , Hutchinson T. C. , Sawa T.
Published: September 2008

Spills of crude oil and various refined fractions are an increasing threat to organisms both in marine and in freshwater situations. The present study is concerned with the effects of aqueous crude oil extracts and naphthalene on one organism, the green flagellate Chlamydomonas angulosa, grown under controlled conditions. Tests were carried out under conditions allowing relatively free evaporation and volatilization of the hydrocarbons (open systems) and in closed systems in which hydrocarbon loss was minimized (closed systems).In open systems, 61% of the Chlamydomonas angulosa cells were killed when saturated naphthalene was initially present in the medium. The generation time of the survivors was, however, the same as the controls. In a closed system a much higher percentage of the cells was killed, but a shorter generation time was observed when growth resumed. A prolonged lag phase was characteristic of all naphthalene treatments.The effect of aqueous extracts of crude oils was also tested using different crude oils, fresh and aged extracts, as well as open and closed systems. Extracts were almost always inhibitory, but the effects were less severe than those obtained with naphthalene. The possible implications are discussed.
Ligule development and fine structure in two heterophyllous species of Selaginella
Authors: Horner Jr. Harry T. , Beltz Carolyn K. , Jagels Richard , Boudreau R. E.
Published: September 2008

Ligules of Selaginella pilifera and S. uncinata were studied by light and electron microscopy. These ligules can be anatomically divided into tip, neck, and basal regions. The upper part of the ligule base is composed of very dense polygonal cells containing many ribosomes, endoplasmic reticulum (ER), and Golgi bodies. In S. pilifera, callose-like walls are secreted around these cells. The lower part of the base consists of wedge-shaped glossopodial cells and the adjacent two layers of sheath cells. Transfer-cell-like walls separate the glossopodium and upper sheath layer, whereas walls containing prominent plasmodesmata separate the two sheath layers. A continuous cuticle covers the entire ligule. During early ontogeny, all ligule cells are highly RNA positive, whereas later only the polygonal base cells stain densely. The anatomy and development of the ligule suggest that it is an active structure. The results of this study are compared with previous studies, especially in relation to ligular function.
Carbohydrate nutrition of Paul's Scarlet rose cell suspensions
Authors: Nash Dudley T. , Boll W. G.
Published: September 2008

Paul's Scarlet rose cells grow equally well on either glucose, fructose, sucrose, or trehalose as a source of carbohydrate. When fructose-containing medium is autoclaved, it becomes inhibitory to growth. The extent of this inhibition appears to be dependent on the physiological age of the cells. Thus as cells enter the stationary phase, they become progressively more sensitive to inhibition by autoclaved fructose, whereas stationary-phase cells transferred to new medium become less sensitive to autoclaved fructose during the first 24 h. The inhibitory compound or compounds produced when fructose-containing medium is autoclaved have not been identified, but they appear to result mainly from the interaction of fructose with magnesium sulfate.
Pollination, female gametophyte, and embryo and seed development in yellow cedar (Chamaecyparis nootkatensis)
Authors: Owens John N. , Molder Marje
Published: September 2008

After dormancy, both pollen- and seed-cone buds resume development early in April at higher elevations on Vancouver Island. Pollen, formed the previous fall, is shed at the one-celled stage during the last half of April. Pollination occurs during a 2-week period. Pollen frequently germinates and elongates in the pollination drop within the micropyle before reaching the nucellus. Pollen tubes penetrate most of the nucellus during May and early June, then pollen-tube growth slows or stops until mid-July when the pollen tubes quickly extend to the surface of the neck cells and two large, equal-sized male gametes form. Meiosis of the megaspore mother cells occurs during April and early May. Female gametophyte development, similar to that in other members of the Cupressaceae, occurs from late May until late July. An archegonial complex forms with an average of nine archegonia. Fertilization occurs at the end of July and proembryo development begins immediately. A file of four free nuclei forms. Considerable variation exists in subsequent nuclear divisions and cell-wall formation. This may result from the long, narrow archegonia and highly variable number of archegonia. A four-tiered proembryo forms and cleavage polyembryony occurs. The embryos reach the multicellular or the massive stage with secondary suspensors by October when the cones, containing ovules which were pollinated in April, become dormant. Embryo and seed development resume the next April, 1 year after pollination, and development is usually complete in July or August. Embryo development occurs more rapidly near sea level but is complete by fall of the year after pollination at all elevations studied. Most seed is shed early in the fall, but some seed may not be shed until January. The distinction is made between immature 1-year-old and mature 2-year-old seeds and cones. Cones contained an average of 7.2 seeds, of which only 29% were filled.