bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of light on peroxidase activity associated with resistance of tomato cultivars to Septoria lycopersici
Authors: Benedict W. G.
Published: September 2008

Peroxidase activity in leaves of tomato, Lycopersicon esculentum Mill, cultivars Bounty, Campbell 1327, Heinz 1350, and Rutgar, infected by Septoria lycopersici Speg. and exposed to various intensities and wavelengths of light was assayed by means of acrylamide flat gel electrophoresis and 3-amino 9-ethyl carbazole stain. Under controlled environmental conditions noninoculated plants of the four cultivars showed similar peroxidase activity during 11 days. Inoculated plants of cultivars Bounty, Campbell 1327, Heinz 1350, and Rutgar, in order, showed increasing resistance to the early blight disease through increasing peroxidase activity in the host and decreasing numbers of lesions produced by the leaf spot pathogen. In decreasing light intensities the inoculated plants of the four cultivars showed increasing peroxidase activity and increasing resistance to the disease, with a notable exception occurring at a light intensity of 14 200 ergs/cm2 per second. When grown in various wavelengths of light the inoculated plants of the four cultivars also showed increasing peroxidase activity and increasing resistance to the disease, respectively, in green (515 nm), orange (640 nm), red (720 nm), yellow (546–550 nm), and blue (430–436 nm) light. The differences in the peroxidase activity per lesion between the control plants grown at 35 500 ergs/cm2 per second of white light and the inoculated plants grown in various decreasing light intensities and in various wavelengths of light were of a magnitude to be highly significant in the parasite–host interrelationship.
Non-staining fungi associated with the bark beetle Dendroctonus brevicomis (Coleoptera: Scolytidae) on Pinus ponderosa
Authors: Whitney H. S. , Cobb Jr. F. W.
Published: September 2008

Three fungi—Ceratocystis nigrocarpa Davidson, an unidentified hyphomycete, and an unidentified basidiomycete—were isolated from extensive non-stained areas of sapwood of ponderosa pine infested with western pine beetle, Dendroctonus brevicomis Lec., in California. The two unidentified fungi were also present in the thoracic mycangium of the female beetle while C. nigrocarpa was found only externally on the beetle. The mycangium and its contents are illustrated. Ceratocystis minor (Hedgc.) Hunt, which was also found externally on the beetle but not in the mycangium, was isolated only from scattered patches of blue-stained sapwood. It is suggested that non-staining fungi play a role in causing the death of ponderosa pine trees attacked by D. brevicomis.
A revision of Halosphaeriaceae
Authors: Kohlmeyer Jan
Published: September 2008

Halosphaeriaceae Müller et v. Arx fam. nov. ex Kohlmeyer, a family of Sphaeriales, is validated and amended. A key leads to the 13 accepted genera. Genera and species are compiled with synonyms. Genera with exclusively marine representatives not included in Halosphaeriaceae are briefly discussed. The following new combinations are proposed: Ceriosporopsis circumvestita (Kohlm.) Kohlm., comb. nov.; C. tubulifera (Kohlm.) Kirk, comb, nov.; Halosphaeria cucullata (Kohlm.) Kohlm., comb, nov.; H. hamata (Höhnk) Kohlm., comb. nov.; H. maritima (Linder) Kohlm., comb. nov.; H. pilleata (Kohlm.) Kohlm., comb, nov.; H. quadriremis (Höhnk) Kohlm., comb, nov.; H. salina (Meyers) Kohlm., comb. nov.; H. stellata (Kohlm.) Kohlm., comb, nov.; and H. truttifera (Kohlm.) Kohlm., comb. nov. Samarosporella pelagica Linder is a nomen rejiciendum.
Germination of ascospores of Hypoxylon mammatum in living aspen
Authors: Anderson Darryl L. , French D. W.
Published: September 2008

Ascospores of Hypoxylon mammatum germinated in the sapwood of naturally occurring trembling aspen. Observed germination never exceeded 7%. There appeared to be no clear relationships between percentage germination and the age of the wound, location in the sapwood, age of the tree, or weather conditions during the incubation period.
Taxonomy of Trifolium (Leguminosae). IV. The American species of section Lupinaster (Adanson) Seringe
Authors: Gillett John M.
Published: September 2008

The American species of Trifolium section Lupinaster are reviewed. A key to the species, descriptions of species which have not been published already in previous papers (Gillett 1965, 1969, 1971, 1972), pertinent synonyms, typification, and distribution maps and notes are provided. The chromosome number 2n = 16 is reported as new for Trifolium douglasii House. A new subspecies, T. andersonii Gray subsp. beatleyae Gillett, is described and the following combinations are made: T. plumosum Douglas subsp. amplifolium (Martin) Gillett, T. gymnocarpon Nuttall subsp. plummerae (Watson) Gillett, T. andersonii Gray subsp. monoense (Greene) Gillett, and T. kingii Watson subsp. macilentum (Greene) Gillett. Morphological relationships are discussed.
Multicompartment analysis of the response of lupin hypocotyl segments to the addition and removal of indolyl-3-acetic acid
Authors: Penny David
Published: September 2008

The typical growth rate curve of the response of lupin hypocotyl to auxin is discussed and explanations suggested for the different parts of the curve. Two alternatives are shown to be able to account for the latent period after auxin addition. One is a linear series of compartments with the transport between compartments similar to allosteric activation in enzyme kinetics and the other alternative is an unmixed compartment (transport delay). Computer simulation is used to test different models to determine whether any model quantitatively predicts the observed results. An example (and variations) of a model is given that predicts much of the experimental results. The model is tested under different conditions such as the addition of different concentrations of auxin, and different times of cycloheximide pretreatment, and on removal from different auxin concentrations. The results of the computer simulations are then compared with experimental results and the model improved to overcome discrepancies. The usefulness of computer simulation in an experimental study is discussed.
The spores of Dryopteris clintoniana and its relatives
Authors: Britton D. M.
Published: September 2008

The perispore morphology of two diploid species, Dryopteris goldiana (Hook.) A. Gray and D. ludoviciana (Kunze) Small; two allotetraploids, D. celsa (Palmer) Small and D. cristata (L.) A. Gray; and the allohexaploid D. clintoniana (D. C. Eaton) Dowell, was examined with the scanning electron microscope. The contributions of the individual genomes of each species as shown by the morphology of the perine were shown, and an attempt was made to extrapolate the contribution to perine phenotype of genome B from an unknown ancestral species B.
Effects of picloram on growth and on chlorophyll, RNA, and protein content of plants
Authors: Sharma M. P. , Born W. H. Vanden
Published: September 2008

Foliar application of picloram (4-amino-3,5,6-trichloropicolinic acid) markedly inhibited the growth of soybean (Glycine max (L.) Merr., cv. Harosoy 63) and Canada thistle (Cirsium arvense (L.) Scop.). The rates of picloram which caused death of soybean (0.14 kg/hectare) and Canada thistle (0.56 kg/hectare) in 2 weeks caused no marked injury symptoms to barley (Hordeum vulgare L. cv. Parkland). ED50 values of picloram (doses required to reduce growth by half) were 16.1 g/hectare for soybean, 18.2 g/hectare for Canada thistle, and 3.64 kg/hectare for barley.Picloram (250 mg/liter, about 0.30 kg/hectare), both 1 and 3 days after treatment, markedly reduced the chlorophyll content of soybean and Canada thistle plants. RNA (ribonucleic acid) and protein contents of such picloram-treated plants, on the other hand, were increased up to 30% over controls. In barley, picloram had very little effect on chlorophyll, RNA, and protein content.
Inheritance of megastrobili colors in Douglas fir (Pseudotsuga menziesii)
Authors: Copes Donald L.
Published: September 2008

Megastrobili color was studied in 7- to 9-year-old progeny resulting from cross-pollinations of parents with green, light pink, light red, or dark red megastrobili. Crosses of green × green parents produced 49% green progeny, while crosses of light red × dark red parents produced only 7% green progeny. Two bract traits, color of margins and tips and color of the central areas, combined to produce whole megastrobili color. Both the central and margin-tip traits appear to be controlled by different multigenes. An epistatic relationship was suggested between genes for central and margin areas.
Granal plastids in the cotyledons of the dry embryo of Kochia childsii
Authors: Marin L. , Dengler R. E.
Published: September 2008

The green cotyledons of the dry embryo of Kochia childsii contain chlorophyll and granal chloroplasts. Epidermal chloroplasts differ from other chloroplasts of the cotyledons in having large electron-dense inclusions and a less well defined internal membrane system. Although chloroplast dimorphism is established during germination, the internal membrane systems of mesophyll and bundle sheath chloroplasts are similar ultrastructurally in the dry cotyledon.
Dark assimilation of acetate-14C by Anabaena flos-aquae
Authors: Tarant A. A. , Colman Brian
Published: September 2008

Acetate is assimilated in both light and dark by the blue-green alga Anabaena flos-aquae. Light uptake has an apparent Km of 6.0 mM and a maximum velocity of 6.0 μmoles/g per hour while the dark uptake rate is lower and proportional to external acetate concentration between 5 and 100 mM.Only 2 to 7% of the acetate-1-14C taken up in the dark is oxidized to 14CO2, and 4 to 5 times as much 14CO2 is released from acetate-1-14C as from -2-14C. Fluoroacetate and α-hydroxypyridyl methane sulphonate inhibit the uptake and release of 14CO2 from acetate in the dark. Radioactivity from acetate-14C is incorporated in the dark mainly into lipids and two amino acids, glutamic acid and leucine. Small amounts of radioactivity are incorporated into a restricted number of organic and α-keto-acids, and triose and hexose phosphates. These results are interpreted as indicating a lack of oxidation of acetate in the dark by a tricarboxylic acid cycle.
Radulodon, a new genus in the Corticiaceae (Basidiomycetes)
Authors: Ryvarden Leif
Published: September 2008

The new genus Radulodon and the species R. erikssonii and R. americanus are described. The latter is a legitimate name for Radulum casearium (Morg.) Lloyd auct. non Morgan. The new combination Radulodon casearium (Hydnum casearium Morg.) is proposed.
Uptake of exogenous DNA by plant protoplasts
Authors: Ohyama Kanji , Gamborg Oluf L. , Miller Raymond A.
Published: September 2008

Uptake by plant protoplasts isolated from cultured cells was demonstrated using Escherichia coli14C-DNA and Ammi visnaga protoplasts. About 0.6 to 2.8% of exogenous E. coli14C-DNA was taken up into the protoplasts, of which about 20% appeared to be acid-precipitable. The time course of uptake, the effect of incubation temperature, and the effects of DNA and protoplast concentration were studied. DEAE-dextran, poly-L-lysine, and poly-L-ornithine were found to enhance the uptake markedly.
Asterobolus: a synonym of Valdensia
Authors: Redhead Scott A. , Perrin Peter W.
Published: September 2008

Asterobolus Redhead & Perrin, based on A. gaultheriae Redhead & Perrin, is a later synonym of Valdensia Peyronel, the correct name of the type species of both generic names being V. heterodoxa Peyronel. The literature pertaining to this species is reviewed. It is suggested that Gloeosporium myrtilli Allescher is a different fungus whose name may not be considered a synonym.
Factors influencing germination of Scolochloa festucacea caryopses
Authors: Smith Alan L.
Published: September 2008

Germination and seedling emergence increased with increasing caryopses weight in Scolochloa festucacea. Maximum seedling survival occurred when caryopses were planted 1 cm deep. Simulation of anaerobic conditions by soaking caryopses increased seedling emergence. Seedling emergence increased after imbibed caryopses were treated in a N2 atmosphere. Emergence also was increased by soaking caryopses in 95% ethyl alcohol up to 60 min. Stratification apparently improved germination but was not a requirement. Scolochloa festucacea caryopses were more tolerant of MgCl2 than NaCl in the germination media. Optimum seedling growth occurred at 20C.
Interaction of culture age and temperature on germination and growth of Curvularia geniculata and on virulence
Authors: Hodges Clinton F.
Published: September 2008

Germination of conidia of Curvularia geniculata from 20-, 40-, and 60-day-old cultures increased as temperature was increased to 15C. At 25C, maximum germination occurred among conidia from 20-day-old cultures, but germination from 40- and 60-day-old cultures decreased at and above 25C. Number and length of germ tubes and primary germ-tube branches increased on all conidia as temperature was increased from 5C to 25C and decreased above 25C. Germination also was influenced by culture age. Total and rate of germination decreased among conidia from older cultures at all temperatures; number and length of germ tubes and germ-tube branches also decreased on conidia from older cultures. Pathogenicity of C. geniculata was not clearly established.
Development and quantitative measurement of microsclerotia of Verticillium dahliae
Authors: Hall R. , Ly H.
Published: September 2008

The development of microsclerotia of Verticillium dahliae from a few swollen hyaline cells on a hypha to a multicellular, pigmented "mature" structure is described and illustrated. A method for quantitatively estimating the amount of pigmented microsclerotial material in pure cultures was developed to study quantitative relations between mycelial growth and production of microsclerotial material in media containing different concentrations of glucose. At low glucose concentrations (0.6 to 10 mg/ml) microsclerotial material continued to increase after total dry weight of the cultures had reached a maximum, suggesting conversion of hyaline to pigmented material. At high glucose concentrations (20 to 60 mg/ml) the patterns of increase in total dry weight, microsclerotial material, and hyaline material were similar over a 4-week incubation period. Maximum production of both pigmented and hyaline materials occurred at a glucose concentration of 30 mg/ml (carbon/nitrogen ratio of 50/1).
Sporulation of Pleurotus ostreatus
Authors: McCracken F. I.
Published: September 2008

In 1968–1970 Pleurotus ostreatus sporophores produced most spores in the afternoon during late fall and winter, when production increased with daily increases in temperature and decreases in relative humidity. In late summer and fall, production peaked between late afternoon and midnight. Diurnal production patterns did not occur in the laboratory at constant temperature, light, and relative humidity. At 85–95% relative humidity, sporulation increased exponentially with temperatures from 1 to 25C. Production ceased at less than 1C and above 27–30C. Alternating temperatures of 5 and 25C at 12-h intervals resulted in corresponding periods of high and low spore production which continued for up to 24 h after treatment ceased. At 17C, sporulation was higher at 30% relative humidity than at 90% relative humidity. Sporulation was unaffected by alternating light and darkness at constant temperature and relative humidity.
Behavior of zoospores of Phytophthora megasperma var. sojae and P. drechsleri in soil
Authors: Mehrotra R. S.
Published: September 2008

Experiments done with the modified soil perfusion apparatus indicate the potential capacity of the zoospores and cysts of Phytophthora drechsleri and P. megasperma var. sojae as inoculum units in soil. The results indicate that although zoospores/cysts do not retain infectivity for months, those of P. drechsleri do not lose it very rapidly. Experiments done to find out the period of motility of zoospores have shown that some zoospores of P. drechsleri and P. megasperma var. sojae remained motile for up to 30 and 24 h respectively. Saprophytic behavior of the two species of Phytophthora has been studied with the help of a fluorescence microscope and using a fluorescent dye. Cysts of P. drechsleri and P. megasperma var. sojae germinate to a moderate degree in natural non-amended soil. Germination ranged from 30 to 50% in the case of P. drechsleri and 15 to 25% in P. megasperma var. sojae. Amending the soil with 0.4% glucose, 0.4% asparagine increased the percentage germination of cysts in natural soil. Germ tubes of a small percentage of cysts in the two species terminate in miniature sporangia-like structures.
Taxonomy of Saxifraga occidentalis and S. marshallii
Authors: Krause David L. , Beamish Katherine I.
Published: September 2008

The taxonomy of Saxifraga marshallii and S. occidentalis is reviewed. On morphological, cytological, and distributional evidence, the new combination S. marshallii ssp. idahoensis is proposed for the taxon originally referred to as S. idahoensis. Keys to the taxa, synonomy, distributional records, maps, and chromosome numbers are presented.
Light microscope and scanning electron microscope observations of Ciboria acerina
Authors: Elliott Mary E. , Corlett Michael
Published: September 2008

The tissue structure and the development of the apothecium of an inoperculate discomycete, Ciboria acerina, were studied using the light transmission microscope and the scanning electron microscope. Attention is drawn to each ascus, paraphysis, interwoven hypha, and cell tissue type more forcibly when viewed with the SEM; otherwise these methods complement each other.
Correlations between lunar phases and rhythmicities in plant growth under field conditions
Authors: Abrami Giovanni
Published: September 2008

A previous investigation of fluctuations in temperature and changes in growth in seven herbaceous species under field conditions revealed a periodic lack of correlation between the two variants. An original step-by-step periodogram analysis of the curves of correlation obtained by plotting growth rate against temperature has been used in the present study. Temperature has been expressed considering the maximum and minimum daily air temperature and the upper and lower threshold values at which the temperature effect on growth is considered to be null. The growth curves, which express observed stem elongation, have been transformed to daily values of growth rate. Using a modified equation of the "logistic curve," which best fits the observed growth pattern, a theoretical representation of growth has been applied to the data. The correlation coefficient has been calculated plotting the values of temperature summation against those of growth rate for periods of 7 days. The stem growth of the seven species has revealed rhythmic components of 29.5-, 14.7-, 9.7-, and 7.3-day periods. The first two components of 29.5 and 14.7 days, which are the most evident, appear to be best correlated with the phases of the new and full moon. This fact suggests that some unknown periodic environmental change is directly or indirectly connected with the position of the moon. The other two shorter components in growth, of 9.7 and 7.3 days, may be endogenous rhythms that are expressive of the overall physiology of stem development of each species.
Computer display graphics for principal-component analysis and vegetation ordination studies
Authors: Kershaw K. A. , Shepard R. K.
Published: September 2008

The interpretation of ordination diagrams obtained from principal-component analysis requires a considerable amount of time-consuming graphical work. Two methods of approach to this problem are described where off-line plotting facilities under the control of a computer-generated tape are used. Examples of both approaches are presented and illustrate both the considerable time saving achieved as well as the power of the methods as research tools.
Naturally occurring perforations in chlamydospores of Thielaviopsis basicola in soil
Authors: Clough Katherine S. , Patrick Z. A.
Published: September 2008

Chlamydospores of the fungus Thielaviopsis basicola (Berk. & Br.) Ferraris, which had been on infected tobacco roots growing in nonsterile soil for 8 weeks or longer, exhibited perforations in the spore walls. These perforations were visible only when viewed in the scanning or transmission electron microscopes. The perforations extended through the wall to the lumen of the cell and were accompanied by loss of spore viability. Bacteria were often seen in association with the perforations. The perforations and loss of viability were not observed in the chlamydospores that had remained in sterile soil. It is believed that microorganisms are likely responsible for the perforations and loss of spore viability.
Perithecium development of Chaetomium longirostre
Authors: Cooke John C.
Published: September 2008

In Chaetomium longirostre, mature perithecia are produced from single uninucleate ascospores. Perithecia are initiated from stalked ascogonial coils that become enveloped by hyphae from the basal cells of the stalk. Growth of the enveloping cells results in a perithecium with an inner pseudoparenchymatous tissue and a membranous outer wall. Formation of the centrum cavity results from deliquescence of pseudoparenchyma cells in advance of the developing binucleate ascogenous hyphae and asci. Asci are produced from croziers. Ascogenous cells occur in a cluster at the centrum base. An ostiole with periphyses produced in the upper portion of the perithecium leads into a hollow beak-like structure formed by perithecial hairs. The mature centrum lacks hymenial and lateral paraphyses. The development of C. longirostre is compared with that of other species.
Nutrient distribution in root zones. III. Further studies of the effects of phosphorus distribution on corn and wheat
Authors: McClure G. W.
Published: September 2008

A technique incorporating several improvements over previous approaches was used to measure responses of plants to several patterns of phosphorus (P) distribution throughout the root zone. Nutrient solutions were moved in and out of three discrete root zones separated by Permagum barriers. Movement was accomplished by an automatic elevating platform which periodically raised solution reservoirs from a resting position to a height sufficient for flushing each compartment with nutrient solution.Root weight increases were observed in those regions where P was present in the root zone. The lower the zone of P supply, the more diminished was the response. These findings were interpreted in terms of sugar translocation and immobilization within the roots. The P and potassium contents of the roots were unaffected by P distribution patterns but calcium and magnesium contents were markedly increased in older tissues where P was present in the ambient solution. These data supported the concept that internally translocated P and externally absorbed P have apparently differing effects at a given root site because the former does not reach the site in the same quantity as the latter. P uptake data suggested that ions absorbed at one point on a root may depress the absorption at a lower point. No significant treatment effects on shoot growth or cation and N contents of shoots were observed. The P content of the shoots, however, was in proportion to the amount of root surface in contact with ambient P.
Floral colors in the high arctic with reference to insect–flower relations and pollination
Authors: Kevan Peter G.
Published: September 2008

Some review, concepts, terminology, and methods are given towards the description of colors, here, of flowers of the high arctic flora of the Canadian Arctic Archipelago, in the insect (including ultraviolet) and human visual spectra. Photographs and spectral reflection curves are given. The various flower colors found elsewhere do not occur in the same proportions in the high arctic where white and yellow predominate. Ultraviolet is reflected from several yellow (insect-red) flowers, making them insect-purple. Patterns and markings in the ultraviolet or other colors may be simple or complex, but cannot be described as honey-guides. To insects, the high arctic flowers of the different species have more distinctive colors and color patterns, and there are more different colors and color patterns, than there are to humans. Most flowers have greater luminance factors than do their backgrounds so stand out as different in color and brightness. Yellow flowers (with or without ultraviolet) are the most attractive to insects; other colored flowers are visited by special groups of insects or when yellow flowers are not available, or both. Color alone cannot account for the attractiveness or unattractiveness of some blooms. Some flower visitors are found in flowers in which they would be least conspicuous, and cryptic color changes may operate in the high arctic crab spider.
The floral biology of Arethusa bulbosa, Calopogon tuberosus, and Pogonia ophioglossoides (Orchidaceae)
Authors: Thien Leonard B. , Marcks Brian G.
Published: September 2008

The reproductive biology of Arethusa bulbosa, Calopogon tuberosus, and Pogonia ophioglossoides was studied in northern Wisconsin. The three species possess a number of floral characters suggesting convergence, yet they remain distinct as a result of isolating mechanisms. Convergence is suggested mainly by the size of the flowers, pink-magenta perianth, lips with yellow-white brushes, and strong absorption of ultraviolet light by the lip brushes. Some of the isolating mechanisms between the species are placement of pollen on the insects, partial seasonal isolation, and chromosomal size and number. The pollinators are various species of bees.
Palaeosclerotium pusillum gen. et sp. nov., a fossil eumycete from the Pennsylvanian of Illinois
Authors: Rothwell Gar W.
Published: September 2008

Numerous isolated fungal sclerotia are present in Middle Pennsylvanian petrifaction material from Illinois. The sclerotia measure about 0.75–1.20 mm in diameter, and are oval-spherical in shape. Individual specimens are constructed of three tissue zones. The interior region or medulla is composed of much-branched, septate hyphae. Spherical cavities about 40 μ in diameter are present within the medulla, and may represent the primordia of reproductive structures. A zone of pseudoparenchyma surrounds the medulla. This cortex is composed of isodiametric or slightly radially elongated cells with dark walls. A rind is present at the outer margin of the sclerotium where the cells are somewhat smaller and exhibit thicker walls than the cells of the cortex. The discovery of these specimens adds to our knowledge of Paleozoic eumycetes, and establishes the presence of sclerotium-forming fungi in the Middle Pennsylvanian.
Comparative ecology of Quebec boreal forests: a numerical approach to modelling
Authors: Bellefleur Pierre , Auclair Allan N.
Published: September 2008

Climatic and species–environmental models for seven regions of Quebec boreal and boreal-transition forest were developed using principal components factor analysis. Climatic models based on growth-relevant meteorological parameters indicated that despite large geographical distances, all regions were very similar. The first principal component in the climatic model accounted for 73% of the total variation in the original climatic variables. Two regions were relatively dissimilar, coinciding with differences in predominant air mass during the growth season.Analytical models of tree species and tree species with environmental variables were based on 1668 forest plots. Compositional and environmental models were similar as were major ecological species–environment relationships among the seven regions. Air and moisture drainage related to catena, natural stand disturbances related to specific edaphic parameters, and microclimate related to slope aspect accounted for 29.7%, 21.5%, and 17.4% of the variance on first, second, and third principal components, respectively. Validity of the models and problems for further investigation are discussed.
Early ontogeny of seedlings of Pinus radiata
Authors: Riding Richard T.
Published: September 2008

The pattern of branching in seedlings of Pinus radiata appeared to be correlated with the size and zonation of the shoot apex. Just before splitting of the seed coat, the apex reached a maximum size and granular storage products, present in the embryo, were no longer evident. Shortly after the seed coat split, the hypocotyl and cotyledons became green. The first needle primordia were formed alternate to the cotyledons. Zonation of the apex was evident at this time; however, the apical zone was homogeneous and cells of the pith–rib-meristem had not elongated. Buds were initiated in the axils of many of the first-formed needle primordia. Needle initiation progressed rapidly up the flanks of the apex, reducing it to a minimum size shortly after the cotyledons emerged from the seed coat. Nodes formed at this time had a low frequency of axillary bud formation. During early epicotyl elongation the rate of needle initiation decreased and cell divisions were evident throughout the apex. The apex then increased in size and developed a zonation similar to that found in mature plants. As the apex increased in size, the frequency of axillary bud initiation also increased.
Development in vitro of surgically halved stamen primordia of tobacco
Authors: Hicks G. S.
Published: September 2008

Tobacco stamen primordia at different developmental stages were surgically bisected and cultured while still attached to the floral meristem. The youngest incised primordia frequently regenerated two stamen primordia each with the characteristic four anther lobes. No regeneration was observed from the oldest stamen rudiments bisected and these formed only half-stamens. It is suggested that normally a stamen rudiment passes through a labile phase and that the pattern of the organ is subsequently fixed in the primordium.
Lipid changes in winter wheat seedlings (Triticum aestivum) at temperatures inducing cold hardiness
Authors: Roche Ian A. de la , Andrews C. J. , Pomeroy M. K. , Weinberger Pearl , Kates M.
Published: September 2008

The changes in total lipid, fatty acid, and lipid phosphorus contents were followed during germination and early growth of Rideau wheat seedlings at 24° for 72 h and 2° for 5 weeks. At both temperatures the changes in total lipids and total fatty acids were similar for seedlings at comparable stages of morphological development. In contrast, the phospholipid content of seedlings grown at 2° was considerably higher than that of seedlings grown at 24°. A marked increase in linolenic acid was also observed during growth at 2°, and this change occurred entirely in the embryo. The results indicate an increased synthesis and unsaturation of membranes in seedlings grown at 2°. The changes may contribute to the increased resistance to freezing temperatures exhibited by seedlings grown at 2°.
Observations on morphological and nutritional aspects of perithecial formation of Nectria haematococca and Hypomyces solani
Authors: Qureshi A. A. , Page O. T.
Published: September 2008

Morphological and nutritional aspects of perithecial formation of Nectria haematococca Berk. & Br. and Hypomyces solani Rke. & Berth, were compared on a variety of media. Maximum perithecial development was observed on "natural" media. In synthetic liquid media, monosaccharides were more suitable for perithecial formation than were other carbon compounds examined. Likewise, amino acids as the sole source of nitrogen were found to be superior to either ammonium or nitrate nitrogen for perithecial production. Further, it was observed that, although light may be stimulatory, it was not an absolute requirement for perithecial induction. Isolates of these species showed remarkable uniformity in the morphology of perithecia, asci, and ascospores. Similarly, the identical response to carbon and nitrogen nutritional requirements for perithecial development substantiates a single identity for the isolates studied.
Production of pectolytic and cellulolytic enzymes by virulent and avirulent isolates of Sclerotium bataticola during disease development in sunflowers
Authors: Chan Yu-Ho , Sackston W. E.
Published: September 2008

Exo- and endo-polygalacturonase, polygalacturonate trans-eliminase, and cellulase were produced in cultures by two virulent, one moderately virulent, and one avirulent isolates of Sclerotium bataticola. The polygalacturonases are important in penetration and early stages of pathogenesis in sunflowers; virulence of isolates is correlated with their ability to produce these enzymes in the host. Polygalacturonate trans-eliminase and cellulase activity in plant extracts increased with time after inoculation. Polygalacturonate trans-eliminase and cellulase are not important in penetration of Sclerotium bataticola into sunflowers, but are involved in further development of the pathogen. Ability to produce these two enzymes in plants is closely correlated with virulence of the respective isolates.
Computer modelling of hyphal tip growth in fungi
Authors: Ricci Daniela da Riva , Kendrick Bryce
Published: September 2008

Starting from simple morphological considerations and a hypothesis involving 'unset' and 'set' wall, a mathematical model simulating the growth of the hyphal tip is derived, and the results displayed by plotter.
Ultrastructural characterization of the basidiomycete septum of Polyporus biennis
Authors: Moore Royall T. , Marchant Roger
Published: September 2008

The septal apparatus of Polyporus biennis comprises a swollen dolipore, a pair of occluding plugs, and perforate parenthesomes differentiated from the wall endoplasmic reticulum. The pore occlusions have an opaque terminal portion and a translucent stem inserted in the pore. The domain between the parenthesome and the dolipore is traversed by microfilaments which may serve to bind the septal apparatus together. Matrix material is present between the parenthesome membranes, producing a lamellar appearance. This unique septum is typical for most basidiomycetes.
Pectic enzymes produced by Pseudomonas fluorescens, an organism associated with “pink eye” disease of potato tubers
Authors: Hagar S. S. , McIntyre G. A.
Published: September 2008

No pectin methylesterase (PME) activity was observed in crude or dialyzed extracts from macerated potato tuber tissue inoculated with Pseudomonas fluorescens; however, pectic lyase (syn. polygalacturonic acid transeliminase, PATE) activity was observed. Two PATE enzymes (peaks 1 and 2) were eluted from a pH 9.4 DEAE-cellulose column using a gradient of pH 7.6 Tris-HCl buffer (0.01–0.1 M). Enzyme in peak 1 was about 6 times more active than enzyme in peak 2 based on reducing group assays, and 10 times more active in viscosity reduction of 1% Na-polypectate (NaPP) at pH 8.5. No increase in absorbancy was observed at 515 nm of clarified reaction mixtures, indicating that saturated oligouronides did not accumulate. Other properties of the two peaks: optimum pH range was 8.5–9.5, substrate preference was NaPP vs. pectin, addition of Ca2+ (0.001 M) enhanced activity while EDTA (0.001 M) decreased activity to [Formula: see text], cellulose acetate electrophoresis revealed one band of protein per peak, and heat of inactivation was 51–60C. Thin-layer chromatography of hydrolytic products from NaPP revealed unsaturated uronides and pectic fragments after 2 h hydrolysis; after 96 h hydrolysis only unsaturated uronides were observed. Molecular weight estimations by Sephadex G-200 gel filtration were about 18 000 (peak 1) and 22 500 (peak 2). Enzyme in either peak macerated 400-μ sections of potato tissue.
Picloram effects on ribonucleic acid and protein biosynthesis in excised plant tissues
Authors: Sharma M. P. , Born W. H. Vanden
Published: September 2008

Picloram (4-amino-3,5,6-trichloropicolinic acid), both at growth-promoting (10 μg/ml) and growth-inhibiting (500 μg/ml) concentrations decreased the loss of RNA (ribonucleic acid) and protein of excised soybean (Glycine max (L.) Merr. cv. Harosoy 63) hypocotyl, barley (Hordeum vulgare L. cv. Parkland) coleoptile, barley leaf, and Canada thistle (Cirsium arvense (L.) Scop.) leaf tissues during an 8-h incubation. At a growth-promoting concentration picloram enhanced RNA and protein biosynthesis (incorporation of 14C-labeled precursors), whereas at a growth-inhibiting concentration it inhibited such synthesis. Incorporation of radioactivity into RNA and protein of particulate and supernatant fractions (separated at 20 000 × g) appeared to be equally sensitive to picloram. Actinomycin D and cycloheximide in the incubation medium markedly inhibited both normal and picloram-induced growth and RNA and protein biosynthesis. Puromycin was less effective in inhibiting growth and protein biosynthesis. Picloram, gibberellic acid, and indoleacetic acid all promoted growth and RNA and protein biosynthesis though they did so at different concentrations and to varying degrees. Our results indicate that picloram has a role in altering both net synthesis of RNA and protein and some processes in the degradative metabolism of these constituents.
The effect of nitrate, nitrite, and ammonia on photosynthesis by Acetabularia chloroplast preparations compared with spinach chloroplasts and whole cells of Acetabularia and Dunaliella
Authors: Grant B. R. , Winkenbach F. , Canvin D. T. , Bidwell R. G. S.
Published: September 2008

The effects of nitrate, nitrite, and ammonia were compared using chloroplasts prepared from Acetabularia mediterranea and spinach and intact cells of Acetabularia and Dunaliella tertiolecta. Nitrate was without effect in all systems. Spinach chloroplasts were strongly inhibited by nitrite at 5 mM, Acetabularia cells were somewhat inhibited, but Dunaliella cells and chloroplast preparations from Acetabularia were unaffected. Ammonia at 5 mM inhibited spinach and Acetabularia chloroplasts, but its effect on the other systems was slight. It decreased oxygen production in chloroplasts and Dunaliella cells, but did not affect carbon dioxide fixation.These results are interpreted on the basis of varying rates of uptake, metabolism, and detoxification of the ions in different preparations. Whole cells and Acetabularia chloroplast preparations make amino acids, but spinach chloroplasts do not. This accounts for the greater sensitivity of the latter, and for the decreased oxygen production in the presence of ammonia in whole cells, which is presumably caused by increased respiration accompanying amino acid formation. The insensitivity of the Acetabularia chloroplast preparation is attributed to the properties of the membrane, apparently derived from tonoplast fragments, which surrounded the small cytoplasmic droplets present in these preparations.
Two new megaspore species from the continental Upper Cretaceous (Campanian–Maestrichtian) of the Alberta Plains
Authors: Campbell J. D. , Untergasser B.
Published: September 2008

Two previously undescribed megaspore entities, one with accompanying microspore, were observed in Upper Cretaceous rock samples collected during coal survey activities in the Plains Region of Alberta.Molaspora reticulata sp. nov. has a spheroidal body 244–398 microns (μ) in diameter with a small prominent neck. Its outer spore wall is thick and profoundly sculptured forming very narrow reticulations with extremely high muri. The spore has been found in strata of middle Campanian and middle Maestrichtian age (Late Cretaceous).Ariadnaesporites macroglebulosus sp. nov. has a spherical body, and a prominent trifolium about as long as the body diameter or slightly shorter. The megaspore central body is 224–373 μ in diameter, while that of the microspore is about 76 μ in diameter. The surface of the spore body is ornamented by extremely coarse, inflated verrucae which, in turn, bear a fine reticulate pattern. From the apex of each verruca arises a hollow filamentous process with an expanded base and usually clavate tip. The processes are about 5 μ in diameter and may exceed 2500 μ in length. This entity has been found in strata of middle Campanian (Late Cretaceous) age.
Fine structure of the septal pore apparatus in Polyporus tomentosus, Poria latemarginata, and Rhizoctonia solani
Authors: Setliff E. C. , MacDonald W. L. , Patton R. F.
Published: September 2008

The septal pore apparatus was studied in Poria latemarginata, Polyporus tomentosus, and Rhizoctonia solani. Fixation by potassium permanganate was compared with fixation by glutaraldehyde – osmium tetroxide. Potassium permanganate reduced the size of the septal swelling about 50% and destroyed much of the internal integrity of the septal swelling. In glutaraldehyde – osmium tetroxide fixed material, a fibrillar network extended from the cross wall throughout the septal swelling. Except for this network, the septal swelling was electron transparent and similar in appearance to a vacuole. A rim of electronopaque material, attached to the septal swelling, surrounded the pore mouth in Polyporus tomentosus and Rhizoctonia solani.
Two unusual tremellas from British Columbia
Authors: Koske R. E.
Published: September 2008

Two mycoparasitic species of Tremella are reported for the first time from North America. Tremella polyporina Reid occurred on tubes of the polypore Tyromyces lacteus (Fr.) Murr., and Tremella uliginosa Karst. was found on the mycelium of a sterile deuteromycete. A conidial stage is described for Tremella polyporina; Tremella uliginosa is redescribed and illustrated.
Aspects of teliospore germination in North American smut fungi. II.
Authors: Duran Ruben
Published: September 2008

Teliospore germination is described for 28 additional species of smut fungi, most of which were recently collected in Mexico.Germination for most species is reported here for the first time. Included are some rarely collected species, some recently described by the author, and some previously unknown to exist in the New World. Where new records of exotic species for North America are indicated, germination was used to verify diagnoses, even though reported by previous workers in some instances. In demonstrating germination, family and generic affinities for most species were corroborated, although one required generic transfer.
Some rusts of Scirpus and allied genera
Authors: Savile D. B. O.
Published: September 2008

Amended descriptions, emphasizing widely neglected aeciospore characters, are given for Puccinia dulichii, P. angustata, P. eriophori var. eriophori and var. apargidii var. nov. (Queen Charlotte Is., British Columbia, on Eriophorum and Apargidium), P. eriophori-alpini,P. congdonii sp. nov. (California, on Scirpus congdonii), P. obtecta,P. osoyoosensis sp. nov. (on Scirpus americanus and S. olneyi), P. liberta, P. fimbristylidis, Uromyces eleocharidis, P. mcclatchieana, U. americanus var. americanus and var. californicus var. nov. (California, on S. californiens), U. lineolatus ssp. lineolatus and ssp. nearcticus ssp. nov. Puccinia angustatoides on Rhynchospora is also discussed because it has been erroneously included in P. angustata.Aecidium ageratinae sp. nov. (on Ageratina spp. = Eupatorium sect. Eximbricata, in eastern North America), and Aecidium eupatorii-rotundifolii sp. nov. (on Eupatorium rotundifolium in southeastern United States) are distinguished from the aecial state of P. eleocharidis. Some aspects of the classification of Scirpus and its allies are briefly discussed in relation to their rusts.
Axenic culture of flax rust isolated from cotyledons by cell-wall digestion
Authors: Lane W. David , Shaw Michael
Published: September 2008

A technique is described for the isolation of colonies of flax rust (Melampsora lini (Ehrenb.) Lév., Race No. 3) from infected cotyledons. The technique depends on the digestion of the host cell walls with hydrolytic enzymes and washing of the liberated colonies. It is thus possible to collect large numbers of flax-rust colonies with only a few host cells adhering to them. Axenic cultures were established from colonies isolated in this way. This technique may be useful in establishing axenic cultures of other rust fungi.
The Trichocomataceae: Ascomycetes with Aspergillus, Paecilomyces, and Penicillium imperfect states
Authors: Malloch David , Cain R. F.
Published: September 2008

The Trichocomataceae Fischer is discussed and shown to be the appropriate family for species of cleistothecial Ascomycetes with Aspergillus, Paecilomyces, and Penicillium imperfect states. The name Eurotiaceae Clem, and Shear is shown to be a later synonym for the Trichocomataceae and the name Aspergillaceae Link to be illegitimate when applied to Ascomycete perfect states. Included in the Trichocomataceae are the following genera: Byssochlamys Westling, Dactylomyces Sopp, Dichlaena Mont. and Dur., Emericella Berk, and Br., Eupenicillium Ludwig, Eurotium Link ex Fr., Gymnoeurotium gen. nov. (type species: Aspergillus athecius Raper and Fennell), Hamigera Stolk and Samson, Harpezomyces gen. nov. (type species: Aspergillus chrysellus Kwon and Fennell), Hemicarpenteles Sarbhoy and Elphick, Neosartorya gen. nov. (type species: Aspergillus fischeri Wehmer), Penicilliopsis Solms-Laubach, Petromyces gen. nov. (type species: P. alliaceus Malloch and Cain), Sporophormis gen. nov. (type species: Aspergillus spinulosus Warcup), Talaromyces Benjamin, and Trichocoma Junghuhn. It is suggested that the genera of Trichocomataceae have evolved from a stromatic ancestor similar to certain present-day Hypocreaceae and have undergone several important evolutionary simplifications and modifications. Evidence of these changes in both the perfect and imperfect states is discussed. Short descriptions are provided for each of the genera and references given to species treatments. A synoptic plate is included for identification of the genera and to illustrate the text.
Fossil woods from the Beaufort Formation (Tertiary), northwestern Banks Island, Canada
Authors: Roy S. K. , Hills L. V.
Published: September 2008

Fossil woods belonging to the Pinaceae (Pinoxylon albicauloides Greguss, 1954; Picea beaufortense sp. nov.; Laricioxylon occidentaloides sp. nov.; Abietoxylon koreanoides sp. nov.; A. traumatiductus sp. nov.) and a single representative of the Eleagnaceae (Eleagnaceoxylon shepherdioides gen. et sp. nov.) are described and illustrated. Two main conclusions are derived from this investigation. They are (1) the fossil woods of the Beaufort Formation are very similar to the woods of some extant arborescent species of northern North America and northeastern Asia and (2) the fossil flora indicates a temperate climate similar to that of the present-day boreal forest.
Carboniferous pteridosperm studies: morphology and anatomy of Schopfiastrum decussatum
Authors: Rothwell Gar W. , Taylor Thomas N.
Published: September 2008

The monostelic seed fern Schopfiastrum decussatum Andrews is described from a specimen collected at a Middle Pennsylvanian petrifaction locality in southern Illinois. The specimen measures 24 cm long and is about 1.1 cm in diameter. Two petioles are attached to the axis and abundant foliar material is also present. Leaf arrangement is alternate and distichous. The stem consists of an exarch protostele surrounded by a prominent zone of secondary xylem. Secondary phloem and a vascular cambium are also preserved. The cortex is characterized by an undulating outer epidermal zone consisting of alternating ridges and furrows; internally this zone is delimited by conspicuous lacunae. Sclerenchyma bands occur in the outer cortex, with prominent resin canals present in the inner cortex. The fronds are represented by dichotomizing rachides, primary pinnae, and laminar pinnules. Features of the plant are compared to those of other Carboniferous pteridosperms, and a reconstruction of Schopfiastrum is included.