bluuebunny/crossref_metadata_2025 huggingface dataset:
Defense reactions of barley cultivars to an inappropriate forma specialis of the powdery mildew fungus of gramineous plants
Authors: Tosa Y. , Shishiyama J.
Published: September 2008

Cellular defense reactions in five barley cultivars against Erysiphe graminis f. sp. tritici were examined in the course of primary and secondary penetrations. In cv. Kairyobozu-mugi, 35% of infection attempts were stopped at fluorescent papillae, and the others (65%) induced fluorescing of epidermal cells, resulting in the failure of the formation of primary haustoria. In the other cultivars ('H.E.S.4', 'Russian No. 12', 'Goseshikoku', and 'Turkey 290') the penetration failures associated with fluorescent papillae reached 50–75%, but the infection attempts that induced the fluorescing of epidermal cells were fewer than 20%. Consequently 10–30% of the germlings that attempted penetration successfully formed normal primary haustoria 48 h after inoculation. In cv. Goseshikoku, cv. Russian No. 12, and cv. H.E.S.4, 50–75% of the epidermal cells that contained the primary haustoria were fluorescent 7 days after inoculation, and colony growth was severely restricted. In cv. Turkey 290 such fluorescent cells scarcely occurred and colonies developed comparatively well. On this cultivar conidia were produced 5–6 days after inoculation, but only in small quantities. This restriction of colony development was mainly attributable to the inhibition of the formation of secondary haustoria by fluorescent papillae. These results indicate that there are differences among barley cultivars in cellular defense reactions against the wheat powdery mildew fungus and suggest that the formation of papillae during the course of primary penetration is not necessarily an essential factor in the resistance of barley to this inappropriate forma specialis.
Vegetative propagation in Rhexia virginica (Melastomataceae): some morphological and ecological considerations
Authors: Posluszny U. , Sharp M. J. , Keddy P. A.
Published: September 2008

The unusual method of vegetative propagation in the rare shoreline plant Rhexia virginica L. was studied using both histological techniques and observations of the external morphology. Several propagules in the form of swollen tuberouslike roots develop adventitiously early in the spring. As the tuberous root forms its periderm, shedding the cortex and epidermis, a number of root buds develop in the region of the phellogen. Approximately two to four root buds per propagule develop as aerial shoots. The rest of the root buds and the tuberous roots themselves degenerate. There was no evidence of propagules and viable root buds surviving for several years, as previously reported. The inability of the tuberous roots to survive in soil for more than a single year may explain, to some extent, why R. virginica is rare in Ontario.
Factors affecting survivorship, growth, and fruit production in a beach population of Xanthium strumarium
Authors: Zimmerman Jess K. , Weis I. Michael
Published: September 2008

In a beach population of Xanthium strumarium, we assessed the effects of density, seedling emergence date, and soil moisture on seedling survivorship, plant growth, and fruit production. Seedling survival was largely density independent, while growth and fruit production declined significantly with increased density. Delayed seedling emergence resulted in significantly lowered survival but exhibited no significant effects on fruit production. Soil moisture was correlated positively with seedling survival, growth, and fruit production. Blowing sand was noted as an important cause of seedling mortality. Increased survival in areas of high soil moisture apparently resulted because of an absence of blowing sand in these areas. Consistent with a lack of density-dependent mortality, the density–yield relationship for the population had a slope near −1 and not −3/2. Hierarchy in fruit production among plants was least developed in areas of high plant density.
A new method for observing the morphology of vesicular–arbuscular mycorrhizae
Authors: Brundrett M. C. , Piché Y. , Peterson R. L.
Published: September 2008

A new procedure using chlorazol black E has been developed for staining vesicular–arbuscular mycorrhizal fungi in cleared roots. In a comparative study, chlorazol black E was found to be much superior to previously used stains (acid fuchsin, trypan blue, aniline blue) for showing details of internal hyphae and particularly arbuscules. This clearing and staining procedure, combined with Nomarski interference contrast microscopy, revealed details of arbuscule structure not evident with previous techniques. Field-collected samples were also stained well by this procedure. The procedure should allow more accurate assessment of roots for colonization by vesicular–arbuscular mycorrhizal fungi.
Karyology and ascus formation in Cordyceps capitata
Authors: Jones John P. , McGawley E. C.
Published: September 2008

Karyology and ascus development in Cordyceps capitata are basically similar to the process described for the majority of higher ascomycetes. There are variations, however, which are evaluated for possible phylogenetic or taxonomic significance. The ascus tip structure is well differentiated. There is a proliferation of a membranous strand, the "tract," into the ascus, as has been reported previously in other ascomycetes. Also reported is the formation of croziers in branching chains as a mechanism for maintaining a dikaryotic ascogenous system.
Temperature effect on biomass production and root/shoot biomass ratios in two arctic sedges under controlled environmental conditions
Authors: Kummerow Jochen , Ellis Barbara A.
Published: September 2008

The effect of differential root and shoot temperatures on biomass production of the arctic sedges Eriophorum vaginatum and Carex bigelowii was analyzed under controlled environmental conditions. Both species showed active growth at 2 °C root and shoot temperatures although warmer conditions substantially enhanced biomass production. In E. vaginatum, under the optimal 12 °C root and 12 °C shoot temperature regime, about six times more biomass was produced than under the 2 °C conditions. The corresponding temperatures for C. bigelowii were 12 °C root and 22 °C air, although the data did not preclude a higher temperature optimum for this species. The results support the hypothesis that in arctic sedges the root/shoot biomass ratios are small with low root temperatures, i.e., a relatively large fraction of the photosynthate is allocated to leaf production under cold conditions.
Pollen transport and representation in the Coast Mountains of British Columbia. I. Flowering phenology and aerial deposition
Authors: McLennan Donald S. , Mathewes Rolf W.
Published: September 2008

Two years of aerial pollen trapping at two lakes surrounded by coniferous forest are summarized. Most of the annual pollen and spore deposition occurs between February and May (86%), followed by 10% during the summer, and 4% during the fall – winter nonflowering period. Annual aerial influx is very similar at both Marion and Surprise lakes, ca. 5000 grains∙cm−2∙year−1. The annual frequency spectra are also equivalent, with a predominance of Cupressaceae (32%) and Alnus (35%), followed by Tsuga heterophylla (8 – 11%), grasses (8 – 10%), and pine (2 – 3%). Regional, rather than local or extralocal pollen, is estimated to account for about 90% of the annual aerial deposition at both lakes. The data also suggest that pollen transport is predominantly upslope in this mountainous area.
Cellular interactions during the formation of approach grafts in Sedum telephoides (Crassulaceae)
Authors: Moore Randy
Published: September 2008

The objective of this study was to determine the competence of epidermal and subepidermal cells to graft. Approach grafts between cut internodal surfaces of Sedum telephoides were characterized by extensive cellular interdigitation at the graft interface. Callus proliferation, but not tissue interdigitation, occurred when these surfaces were separated by a porous or impermeable barrier. Graft partners adhered to the barrier via the deposition and subsequent polymerization of cell wall materials. The outer walls of cells contacting the barriers were of uniform thickness and lacked plasmodesmata. When a cut surface was grafted to an intact surface, callus proliferation occurred at the cut surface, but the epidermis did not dedifferentiate. Callus masses at cut surfaces grafted successfully in environments of high humidity. However, callus masses covered by a water stress induced periderm did not graft successfully. These results indicate that (i) intact epidermal cells of S. telephoides are incompetent to graft, (ii) the presence of a graft-competent (i.e., cut) surface does not cause epidermal cells to dedifferentiate (i.e., become competent to graft), and (iii) graft competence of compatible, subepidermal surfaces depends on the absence of a periderm, which is facilitated by low moisture stress.
Inoculations of Scrophulariaceae with Cronartium ribicola
Authors: Hunt R. S.
Published: September 2008

Species of Castilleja, Pedicularis, Rhinanthus, (Scrophulariaceae), and Ribes (Grossulariaceae) in their native habitat were inoculated with aeciospores of the white pine blister rust fungus, Cronartium ribicola J. C. Fischer ex Rabh. Only Ribes spp. became infected.
Mycorrhizal inoculum in a peat deposit formed under a white spruce stand in Alberta
Authors: Danielson R. M. , Zak J. C. , Parkinson D.
Published: September 2008

A feather moss peat deposit formed under white spruce in the foothills of the Rocky Mountains in Alberta, Canada, was assessed for the occurrence and type of ectomycorrhizal and vesicular–arbuscular (VA) mycorrhizal endophytes. Three profiles were excavated within the deposit and samples were obtained from the 20- to 30-, 50- to 60-, and 80- to 90-cm depths. A greenhouse bioassay using jack pine and slender wheatgrass demonstrated that mycorrhizal inoculum was present in the peat, though the distribution of inoculum was patchy. While ectomycorrhizal inoculum was present in all profiles and at all depths, fungi which could form mycorrhizae with slender wheatgrass were absent from one profile and did not occur in the 20- to 30-cm layer of a second. Twelve fungi formed ectomycorrhizae with jack pine including an E-strain fungus and Cenococcum geophilum. The most common jack pine symbiont was an unknown ascomycete which produced cystidial ectomycorrhizae. Basidiomycetes present included Tomentella sp., Amphinema byssoides, and two Rhizopogon-like species. Only one species of VA fungus, Glomus aggregation, was associated with slender wheatgrass roots. Viable chlamydospores of VA fungi were not detected in the peat deposit.
Anatomy and histochemistry of Abies balsamea cambial zone cells during the onset and breaking of dormancy
Authors: Riding R. T. , Little C. H. A.
Published: September 2008

The anatomy and histochemistry of fusiform cambial zone cells were investigated (i) in shoots producing latewood tracheids at the time of collection in July and (ii) in dormant shoots. The latter were naturally or artificially chilled to obtain different stages along the rest–quiescence continuum, then placed for 4 weeks under environmental conditions favoring growth. The transition from active growth to rest was associated with increases in RNA, protein, and total insoluble carbohydrates and in peroxidase and succinic dehydrogenase activities. The rest–quiescence transition was correlated with additional increases in RNA and protein, an increase in lipid staining, radial wall thickness and plasmalemma infolding, and a decrease in vacuolar size. The DNA level did not appear to change; however, a distinct color shift occurred in nuclei stained for total protein. During the 4-week growth period, RNA, protein, total insoluble carbohydrates, and lipids decreased, most obviously in cambia that were fully quiescent at the start of the period. Xylem production and percentage of buds flushing during the growing period increased as the initial dormancy stage changed from rest to quiescence. Little, if any, xylem production occurred in debudded shoots unless indol-3-ylacetic acid (IAA) was supplied. Endogenous and exogenous lAA induced the same anatomical and histochemical responses.
Biologie du chénopode blanc (Chenopodium album): influence du travail du sol sur la levée et de la densité du peuplement sur la croissance
Authors: Lapointe Anne-Marie , Deschenes Jean-Marc , Gervais Paul , Lemieux Claudel
Published: September 2008

The emergence pattern and the effects of density on population growth of lamb's-quarters (Chenopodium album L.) were studied in field and greenhouse experiments. Seedling emergence occurred from May to July but reached a maximum during the last 2 weeks of June. Harrowing, performed from the middle of May to the beginning of June, increased considerably the emergence of the species. According to the time of their emergence, the seedlings of each population of lamb's-quarters were grouped into different cohorts. Most plants (87% in 1981 and 42% in 1982) belonged to the first cohort. Those early emerging plants produced 90% of the total biomass and were least subject to mortality. Plants of the late cohorts were few, produced little biomass, and tended to die younger. Populations of lamb's-quarters reacted to density stress mostly through phenotypic plasticity. Mortality occurred mainly in high density populations. Average dry weight per plant was inversely related to density. Height and weight distribution of mature populations followed a hierarchical pattern. Most individuals were of low height and weight, while a few plants dominated the canopy.
Variabilité du nombre chromosomique chez les pleurotes des ombellifères
Authors: Slézec Anne-Marie
Published: September 2008

Meiosis in three "species" of Pleurotus (Pleurotus eryngii, Pleurotus ferulae, Pleurotus nebrodensis) from umbellifers of different geographic origins proceeds principally in an orthodox manner. It is followed by a postmeiotic mitosis, but the basidiospores formed are mostly uninucleate. Three-dimensional reconstructions from serial sections of pachytene synaptonemal complexes make it possible to determine that the chromosome number is different in each "species," and in P. eryngii, according to the geographic origin.
Sympodial and annellidic conidiation in Ceratocystis clavigera
Authors: Tsuneda Akihiko , Hlratsuka Yasuyuki
Published: September 2008

Ceratocystis clavigera (Robins.-Jeff. & Davids.) Upadhyay produces the Craphiocladiella anamorph in pupal chambers of the mountain pine beetle (Dendroctonus monticolae Hopk.) in mature lodgcpolc pine. Besides this anamorph, at least five different sympodial or annellidic anamorphs occur in culture. These are a hyaline Verticicladiella-like state, a Hyalorhino-cladiella state, a holoblastic-yeast state, a Leptographium state, and an annellidic-yeast state. Apparently, interconversion between sympodial and annellidic ontogenies occurs. As the cultures are repeatedly transferred on agar media, relative dominance of these states tends to shift from complex to simpler forms in both ontogenetic lines, and conidia tend to become smaller and roundish. Results of this study urge the necessity for condensation of some ontogenetically and anatomically based anamorph genera connected to Ceratocystis Ellis & Halst.
Competition between plants of different successional stages: mycorrhizae as regulators
Authors: Allen Edith Bach , Allen Michael F.
Published: September 2008

Salsola kali, a colonizing annual which does not form vesicular–arbuscular mycorrhizae (nonmycotrophic), was grown in pure culture and in mixtures with two mycotrophic grasses which are late successional dominants, Agropyron smithii and Bouteloua gracilis. Soils were either left sterile or inoculated with mycorrhizal fungi. In pure culture mycorrhizae caused no significant increase in dry mass of either grass, but in mixed culture with S. kali, mycorrhizal infection was significantly related to increased mass of grasses. Mycorrhizal infection was related to increased stomatal conductance of the grasses in both pure and mixed culture. Salsola kali had lower stomatal conductance but not a significantly reduced mass with mycorrhizal fungi. Hyphae of mycorrhizal fungi, but not vesicles or arbuscules, were observed in the rhizosphere and occasionally the cortex of S. kali. Where competition between colonizing nonmycorrhizal species and later successional mycorrhizal species is a mechanism which drives succession, the inoculum density may determine the rate of succession.
Chromosome numbers in Impatiens (Balsaminaceae)
Authors: Zinov'eva-Stahevitch A. E. , Grant W. F.
Published: September 2008

Chromosome numbers were determined for 44 taxa of Impatiens. Ten of these are reported for the first time, of which one is the first record for a species native to Borneo. Chromosome numbers ranged from n = 3 to n = 24. Three new dysploid cytotypes were observed. A chromosome number of n = 17, previously recorded only from Thailand and Malaysia, was found in a South Indian taxon whose putative hybrid origin is discussed. The frequency of the different chromosome numbers occurring in the genus (n = 3 to n = 33) is summarized and dysploidy and polyploidy are discussed.
Comparative study of the U1, U4, and U7 strains of tobacco mosaic virus
Authors: Asselin Alain , Tremblay Colette , Bellemare Guy
Published: September 2008

Experiments were undertaken to compare three strains of tobacco mosaic virus (TMV) belonging to the tobacco group 1 of the tobamoviruses. Although the U1, U4, and U7 strains of TMV differ significantly in virulence, it was shown that these strains are very closely related. No difference was detected in the major spots of the coat protein tryptic maps and the virions from the three strains shared the same electrophoretic mobility in agarose gels with different buffer systems. The RNA fingerprints of U1 and U7 were indistinguishable and the largest T1 omega fragments of the three strains were identical in size. However, the avirulent U4 RNA fingerprint exhibited a single spot mobility difference from the U1 and U7 RNA fingerprints. This spot corresponded to the T1 phi fragment. This unique fragment is located in the so-called l2 gene between nucleotides 976 and 992 from the 3′ end. This suggests and extends the proposal that the l2 gene is most probably implicated as a factor in the control of virulence (symptomatology).
Étude des isoenzymes de polygalacturonases, d'endoglucanases de Rhizopus spp. et Mucor spp. et différenciation d'isolats dans le sud-est de la France
Authors: Nguyen-The Christophe , Bertheau Yves , Coleno Alain
Published: September 2008

Patterns of polygalacturonase and endoglucanase isoenzymes of numerous Rhizopus stolonifer isolates (sampled in peach orchards and storage stations) were studied by electrophoresis and isoelectric focusing. Three groups of R. stolonifer were characterized in the southeast of France. A similar investigation of a few isolates from other Mucorales was performed to compare R. stolonifer to some related species. These techniques could also be useful to characterize the species of Mucorales studied. To improve the reliability and accuracy of our results it was necessary to compare zymograms obtained by different techniques (electrophoresis and isoelectrofocusing). An electrophoretic mobility curve method was found useful in the interpretation of the enzyme spectra.
Canadian and some extralimital Leptosphaeria species
Authors: Shoemaker R. A.
Published: September 2008

Sixty-one species are illustrated and described from Canada or extralimital regions. Four other species are discussed briefly and their disposition is suggested. Keys to species and to allied genera are provided. Fourteen new species are proposed: L. asclepiadis. L. barriae, L. brightonensis, L. castillejae, L. castrensis, L. darkeri, L. dearnessii, L. jacksonii, L. nanae, L. noveboracensis, L. russellii, L. shastensis, L. staritzii, and L. wehmeyeri. Leptosphaeria jacksonensis nom. nov. is proposed for L. tetonensis Wehmeyer non L. tetonensis (Ellis & Everhart) Rehm. Diapleella clivensis (Berkeley & Broome) Munk and Passeriniella discors (Saccardo & Ellis) Apinis & Chesters, though generically distinct, are treated because they are sometimes referred to Leptosphaeria.
The reproductive biology of Hydrocharis morsus-ranae. I. Floral biology
Authors: Scribailo Robin W. , Posluszny Usher
Published: September 2008

Hydrocharis morsus-ranae L. is a Eurasian aquatic plant introduced to North America. It spreads primarily by the rapid production and growth of stolons and overwintering turions but still flowers extensively. The white, trimerous flowers of H. morsus-ranae are emergent and unisexual, with male flowers clustered in a cyme of up to five buds and females always solitary. Both sexes of flowers, once open, last a single day, with individual male flowers opening sequentially from a given inflorescence but not necessarily on successive days. First openings in the corollas of flowers were visible by 0730 and maximum expansion was usually reached by late morning. Anthers dehisce and stigmas become receptive by 0930 with both reaching maxima by midday. The flowers produce a sweet nectar and scent which attract, and are easily accessible to, a wide variety of insects visiting the open bowl-shaped flowers. The most abundant insect visitors to the flowers were Homoptcra (Aphididae) and Hydrellia and Notiphila spp. (Diptera: Ephydridae). Both groups were found to carry small pollen loads and because of their erratic anthophilous behaviour were not considered important in pollination. Although fewer in number, the more specialized hover flies, Toxomerus marginatus (Say) (Diptera: Syrphidae), and solitary bees, Dialictus sp. (Hymcnoptera: Halictidae), were considered more likely to be the primary pollinators. After pollination and the day after anthesis, female flowers are drawn underwater by pedical recurvation and 4–6 weeks later mature into globose berrylike fruits. Fruit-sets were 38.3% in naturally pollinated flowers, 96.5% in bagging experiments with hand-pollinations, and absent in bagging experiments for agamospermy with unopened flowers. These results substantiated that poor fruit-set in some populations was caused by a lack of effective pollinators. Seed densities of 250/m2 were still estimated with the above data.
Influence of temperature and moisture on growth and sporulation of Botrytis squamosa
Authors: Alderman S. C. , Lacy M. L.
Published: September 2008

Growth of Botrytis squamosa in artificial media or autoclavcd onion leaves was favored at temperatures of 15 or 20 °C but was much less at 30 °C or above. Hyphae did not grow in artificial media or autoclaved onion leaf segments below −95 to −100 bars (1 bar = 100 kPa) water potential within 4 days at 20, 25, or 30 °C. Growth was stimulated when water potential was adjusted to −5 to −20 bars compared with higher or lower values. Mycelia of B. squamosa survived air drying in autoclaved leaf segments for 12 days at 20 °C. When colonized dried leaf segments were placed on water agar, sporulation began after 2 days and continued through 6 days. Sporulation from colonized dried leaf segments was abundant at 15 or 20 °C, less at 25 °C, and absent at 35 °C. When subjected to alternate wetting and drying periods, sporulation on colonized dried leaf segments decreased with increasing length of the dry period.
Interactions between embryo and endosperm during early developmental stages of maize caryopses (Zea mays)
Authors: Schel J. H. N. , Kieft H. , Lammeren A. A. M. Van
Published: September 2008

The early developmental stages of maize caryopses were studied at a fine structural level. Emphasis was placed on the interactions between the developing embryo and the surrounding endosperm. It was found that the placentochalazal region of the endosperm contains cells showing ultrastructural features of transfer cells, including wall ingrowths. This indicates an important function of these cells in the transport of nutrients supplying the developing embryo. Near the basal region of the embryo, densely cytoplasmic endosperm cells occurred, without wall ingrowths but with a mass of highly ordered rough endoplasmic reticulum indicating a synthesis function of this part of the endosperm. The products, probably membranes and proteins, are most likely taken up by the suspensor of the embryo. At about 7 days after pollination, endosperm cells degenerate near the embryo axis and the scutellum. The endosperm remnants might then serve as a food supply for the embryo as well.
Position et orientation des mitoses dans la zone organogène de jeunes feuilles de Fraxinus excelsior, Glechoma hederacea et Lycopus europaeus
Authors: Jeune B.
Published: September 2008

Whether the leaf is simple (Lycopus, Glechoma) or compound (Fraxinus), pinnate (Lycopus, Fraxinus) or palmate (Glechoma) in its nervation or leaflet arrangement, and acropetal (Fraxinus) or basipetal (Lycopus, Glechoma) in its development, the organogenetic zone of its primordium is characterised by a continuum of meristematic activity, a submarginal optimum mitotic density, a mitotic polarity (the main cause of lobation) and a very important individual variability.
Pollen vectors in sugar maple (Acer saccharum)
Authors: Gabriel William J. , Garrett Peter W.
Published: September 2008

To determine whether insect vectors alone are responsible for all of the pollination that occurs in sugar maple (Acer saccharum Marsh.), pistillate flowers of three trees in Vermont were covered with fine mesh bags. This procedure provided evidence that this species can receive sufficient pollen for pollination by wind alone, although both insects and wind are factors in pollen distribution under optimal weather conditions.
Resistance to the rust fungus Puccinia poae-nemoralis in Poa pratensis induced by low-temperature hardening
Authors: Tronsmo Anne Marte
Published: September 2008

Four different cultivars of Poa pratensis were exposed to a physical stress (low-temperature hardening) before inoculation with an obligate parasite, Puccinia poae-nemoralis. Compared with the unhardened control plants, hardened plants of all cultivars showed significantly increased resistance to the pathogen. The effect was most pronounced on the most susceptible cultivar. These results indicate that low-temperature hardening of plants can trigger some natural defence mechanisms against plant pathogens.
Transmission of Atkinsonella hypoxylon (Clavicipitaceae) by cleistogamous seed of Danthonia spicata (Gramineae)
Authors: Clay Keith , Jones J. P.
Published: September 2008

Atkinsonella hypoxylon is a systemic parasite of the grasses Danthonia spicata, D. compressa, and Stipa leucotricha. The means by which this fungus and other Balansiae (Balansia, Balansiopsis, Epichloë, and Myriogenospora) are transmitted from one plant to another is poorly understood. Host grasses of A. hypoxylon normally produce spikelets of open, wind-pollinated chasmogamous flowers at the apex of the flowering culm and spikelets of self-pollinated cleistogamous flowers in the lower leaf sheaths of the same culm. Plants of D. spicata infected by A. hypoxylon regularly produce cleistogamous spikelets in the lowermost leaf sheaths, although chasmogamous spikelets are aborted by hypothallus development. Embryos of the seeds resulting from these flowers were surrounded by hyphae. The seeds were germinated and when the plants flowered, they produced deformed flowering culms and hypothalli, indicating that A. hypoxylon is transmitted from parent to offspring through cleistogamous seed.
New trends in phytochemistry and Plant senescence and postharvest physiology
Authors: Dumbroff E. B.
Published: September 2008

On the occasion of its Silver Anniversary Meeting, the Canadian Society of Plant Physiologists was honored to host two international symposia on the topics of "New trends in phytochemistry" and "Plant senescence and postharvest physiology." The recent surge of interest in the chemistry of secondary plant products can be attributed, at least in part, to the economic challenge of and new developments in biotechnology. However, additional impetus for the discipline derives from a blurring of traditional distinctions between primary and secondary metabolites, and plant scientists and biochemists now recognize that many compounds heretofore labelled as nonessential products of secondary metabolism actually play crucial physiological and ecological roles in the growth, development, and survival of plants.The complexity and elegance of several of the physiological phenomena that characterize senescence and postharvest physiology of cells and tissues are no less compelling of our attention. Certainly, few other areas of research endeavor in the plant sciences hold more promise of socioeconomic benefit from the practical application of fundamental knowledge if we can but learn to control and manipulate some of the biochemical processes that occur in postharvest fruits, flowers, and vegetables.To each of the participants in the symposia, the Society offers its sincere thanks for presenting ideas and hypotheses that stimulated both discussion and controversy and will surely affect the course of future research. We also thank Dr. Ian de la Roche for his services as chief editor of these reports and we gratefully acknowledge the generous financial support from the Natural Sciences and Engineering Research Council of Canada that made it possible to convene these sessions.
Interactions of light with phytochemicals in some natural and novel systems
Authors: Towers G. H. N.
Published: September 2008

An increasing number of phytochemicals, including phenols, terpenoids, polyketides, and alkaloids, are being recognized as photochemically active substances or photosensitizers. These compounds, unlike the photosynthetic pigments or the phytochromes, do not have any known functions in the plant species in which they occur. However, when introduced into other biological systems, e.g., cells or complex organisms, many of them arc extremely toxic in light. The cellular targets and the photochemical processes for some of them have been defined. In one type of process there is cycloaddition of the photosensitizer with a nucleic acid base, e.g., the formation of a photoadduct of a furanocoumarin such as 8-methoxypsoralen with thymine in a nucleic acid. Certain alkaloids including furanoquinolines. β-carbolines, canthinones, and certain furanochromones and chromenes appear to be of this type; they are photogenotoxic, giving rise to gross chromosomal aberrations in light. A second type of photoreaction, inherently bimolecular, often leads to oxidations. A very large group of phytochemicals, particularly the polyacetylenes and their thiophene derivatives, belong here. These compounds, characteristic of the Compositae and about 20 other families of flowering plants as well as basidiomycetous fungi, are powerful photosensitizers whose main targets in the phototoxicity process arc cell membranes. A number of natural derivatives of the chlorophylls are also in this class. The uses of some of these photosensitizers in photochemotherapy are presented. In contrast to these phototoxic reactions there are other photochemical processes occurring in plants whose significance is not yet understood. One of these processes leads to structural change in molecules, e.g., synthesis of vitamin D in plants. A fourth process is the light-directed E→Z (trans–cis) isomerism of cinnamic acid derivatives. This important stereochemical change may account for phototropism and spatial orientation in some plants.
Biochemistry and function of cutin and suberin
Authors: Kolattukudy P. E.
Published: September 2008

Cutin, the structural component of plant cuticle, is a biopolyester composed of hydroxy- and hydroxyepoxy-fatty acids. The major monomers are a 16-hydroxy C16 acid, a 10,16-dihydroxy C16 acid together with its positional isomers, 18-hydroxy C18 acids, 18-hydroxy-9,10-epoxy C18 acids, and 9,10,18-trihydroxy C18 acids. The hydroxylation, epoxidation, and epoxide hydration reactions postulated to be involved in the biosynthesis of these monomers have been demonstrated in tissue slices and in cell-free preparations. The synthesis of the polymer occurs by the enzymatic transfer of the hydroxyacyl groups from CoA to the free hydroxyl groups in cutin primer. Natural and wound periderms and a variety of internal barrier layers contain a somewhat analogous polymer called suberin. This polymer is probably composed of aromatic domains somewhat similar to those found in lignin and aliphatic polyester domains somewhat similar to cutin. The chemical composition and biosynthesis of this polymer is discussed. Pathogenic fungi use a hydrolytic enzyme, cutinase, to gain entry into the plant through the cuticle. The fungal cutinase has been isolated from a variety of pathogenic fungi and characterized. This enzyme is a "serine hydrolase" containing the characteristic catalytic triad. The primary structure of this enzyme has been determined using both amino acid and nucleotide sequencing of the cloned copy DNA. Inhibition of cutinase was shown to prevent fungal infection of plants. This novel approach to fungal control is described.
Monilia versiformia sp. nov. (Hyphomycetes) from a perennial Douglas-fir canker
Authors: Funk A.
Published: September 2008

Monilia versiformia sp. nov. is a pleoanamorphic fungus producing two types of blastoconidia, viz., monilioid chains of dark-colored, sphaeroid conidia and lunate, hyaline conidia produced singly on simple, conidiogenous hyphae. The chains are produced in great abundance, and as the conidia mature and become pigmented, the chains break down and form a sooty mass. The fungus was isolated from a perennial canker of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in British Columbia, Canada.
Development of microsclerotia by Coprinus psychromorbidus
Authors: Gaudet D. A. , Kokko E. G.
Published: September 2008

The development of microsclerotia in nonsclerotial strains of Coprinus psychromorbidus Redhead and Traquair was studied using light, scanning, and transmission electron microscopy. On winter wheat in a controlled environment, microsclerotia originated through swelling of terminal and intercalary projections in elongate hyphae to produce small, spherical cells. These spherical cells increased in number through prolific budding. Initially they existed in leaf tissues as free cells but by 11 – 14 weeks had formed loose aggregations. At an advanced stage, further budding development was accompanied by a decrease in cell size and a small increase in cell wall diameter. Accumulation of a mucilaginous matrix and electron-dense material between spherical cells and lipid bodies and vacuoles within the cells accompanied maturation of the microsclerotium. Following near total conversion of leaf tissues to fungal thallus after 20 weeks of incubation, microsclerotia formed a single large continuous body between remnants of the epidermis. In winter wheat and fall rye plants naturally infected with C. psychromorbidus, microsclerotia were abundant and developed intercellularly and intracellularly. Often the development of the fungus was extensive near the crown tissues and microsclerotia appeared as white plaques embedded within the leaf sheaths.
Les hydathodes des genres Begonia et Hillebrandia (Begoniaceae)
Authors: Brouillet Luc , Bertrand Charles , Cuerrier Alain , Barabé Denis
Published: September 2008

The hydathodes of Hillebrandia sandwicensis and of Begonia augustinei, B. coccinea, B. phyllomaniaca, B. salicifolia, and B. vellozoana are described. Begoniaceae have typical epithem hydathodes. Indirect measures of ploidy level (number of chloroplasts per guard cell, stomatal size) indicate that aquiferous stomata could be endopolyploid relative to aeriferous ones. The epithem comprises nonmoruliform cells, and the intercellular spaces are small. Elongated epithemial cells are intermixed with tracheids, and the stomatal chamber is lined by isodiametric epithemial cells. Elongated parenchyma cells sheath the hydathode. The enlarged vein is excentric and asymmetrical, as has been described for the "begonioid" tooth; however, the tooth is not tylate (i.e., with a pad of dense cells which would correspond to the epithem), as its apex is composed of parenchymatous cells. The hydathodes of Begoniaceae species vary in size, in position of the aquiferous stomata, in size of the chamber, and by the presence or absence of tanniferous cells or macrosclereids. Hydathodes, as well as other anatomical characters from the margin, might prove useful in taxonomic and phylogenetic studies of the Begoniaceae.
Phenology and temperature tolerance of the red algae Chondria baileyana, Lomentaria baileyana, Griffithsia globifera, and Dasya baillouviana in Nova Scotia
Authors: Novaczek I. , Bird C. J. , McLachlan J.
Published: September 2008

The warm-temperate species Chondria baileyana, Lomentaria baileyana, Griffithsia globifera, and Dasya baillouviana are restricted, north of Cape Cod on the eastern American coast, to embayments and estuaries. The northern limit of distribution is the southern Gulf of St. Lawrence. In culture, isolates of these species from Nova Scotia survived 28 to 34 °C. In the field all reproduced during the period of maximum temperature, and in G. globifera and C. baileyana the progeny also reproduced. Some of the progeny of D. baillouviana developed as cold- and heat-resistant pads that survived the winter, whereas the other three species died back to perennating holdfast structures. Lomentaria baileyana was the least successful of the group, being unable to form resistant holdfast pads in midsummer temperatures and having the most limited reproductive period and smallest population size.
Ontogeny and fine structure of effective root nodules of the autumn olive (Elaeagnus umbellata)
Authors: Newcomb William , Baker Dwight , Torrey John G.
Published: September 2008

An ultrastructural study of effective root nodules of the autumn olive (Elaeagnus umbellata Thunb.) demonstrated the presence of hyphal and vesicular forms of the actinomycete endophyte. No sporangial forms of the endophyte were observed within these nodules. The hyphae contained septa, prominent nucleoid regions, and many ribosomes. The endophytic vesicles were initially nonseptate and then became multichambered as a result of the inward growth of complete and incomplete septa. Glycogen particles were numerous in nonseptate and early stages of septate endophytic vesicle formation and in adjacent hyphae but were absent in more developed stages of septate endophytic vesicles. The endophytic vesicles also contained prominent nucleoid areas, vesicular mesosomes, and crystalline-like striated bodies. A capsule, probably derived from host Golgi cisternae and profiles of dilated rough endoplasmic reticulum, surrounded both forms of the endophyte. The endophytic vesicle cell walls consisted of an outer layer continuous with the hyphal cell wall, a middle clear area or “void space,” and an electron-dense inner layer. The “void space” of the endophyte cell wall was resolved into many thin laminae by freeze–fracture microscopy. The laminae were presumed to be different from the outermost cell wall layer because they were washed out in the solvents used in preparing specimens for the TEM.
Entomocorticium dendroctoni gen. et sp. nov. (Basidiomycotina), a possible nutritional symbiote of the mountain pine beetle in lodgepole pine in British Columbia
Authors: Whitney H. S. , Bandoni R. J. , Oberwinkler F.
Published: September 2008

A new basidiomycete, Entomocorticium dendroctoni Whitn., Band. & Oberw., gen. et sp. nov., is described and illustrated. This cryptic fungus intermingles with blue stain fungi and produces abundant essentially sessile basidiospores in the galleries and pupal chambers of the mountain pine bark beetle (Dendroctonus ponderosae Hopkins Coleoptera: Scolytidae) in lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.). The insect apparently disseminates the fungus. Experimentally, young partially insectary reared adult beetles fed E. dendroctoni produced 19% more eggs than beetles fed the blue stain fungi.
Nuclear division and chromosome behavior during meiosis and ascosporogenesis in Pyricularia oryzae
Authors: Leung Hei , Williams P. H.
Published: September 2008

Meiosis and mitoses during ascosporogenesis in fertile mating strains of Pyricularia oryzae Cavara (teleomorph: Magnaporthe grisea) were studied using a propionic–iron–hematoxylin procedure which stained chromosomes, nucleolus, and spindle pole bodies. Meioses and mitoses in P. oryzae resembled those in other ascomycetes. Zygotene chromosomes were highly contracted followed by elongation at pachytene when close pairings of homologous chromosomes were observed. Nucleoli attained a maximum diameter of 3.8 μm during pachytene. Nucleolar growth was accompanied by a rapid growth of the ascus. Chromosome lengths varied among pachytene cells, with the longest chromosome averaging 8.5 and the smallest 2.9 μm. Telomeric knobs and chromomeres were discernible on fully extended pachytene chromosomes. Six chromosomes were observed at pachytene and diakinesis, and during metaphase of ascospore mitosis. Chromosome movement at meiotic and mitotic anaphase was asynchronous, resulting in lagging chromosomes. Electron microscopic observations revealed spindle pole bodies associated with profusion and early meiotic prophase nuclei. In pachytene nuclei, 50 nm wide structures resembling synaptonemal complexes were observed.
Ultrastructure and influences of temperature on the in vitro production of Coprinus psychromorbidus sclerotia
Authors: Traquair James A. , Gaudet Denis A. , Kokko Eric G.
Published: September 2008

The effects of temperature on the production of sclerotia by the snow mold basidiomycete, Coprinus psychromorbidus, are described for the first time. Numbers of sclerotia produced and the optimum temperature for sclerotium production were variable for isolates observed. In general, the influence of temperature on sclerotium production was independent of its influence on colony growth. Optimal temperatures for production of sclerotia were higher than those for radial growth of colonies. Scanning electron microscopy revealed a centripetal pattern of differentiation in developing sclerotia. Distinctive rind, cortex, and medulla were evident after 8 to 10 weeks. Rind and cortex were multilayered. Thick-walled cells were cemented together by an amorphous intercellular matrix. Melanin was located in the rind cell walls for the first time by scanning electron microscopy and backscattered electron imaging of silver-stained sections. With the transmission electron microscope, melanin granules were observed only in the intercellular matrix and outer layers of rind cell walls. Inflated medullary cells were predominantly thin walled and contained vacuolate cytoplasm.
Microscopie de la mycoflore des aiguilles de sapin (Abies alba). III. Marasmius androsaceus
Authors: Gourbière François , Pépin Régis , Bernillon Dominique
Published: September 2008

Marasmius androsaceus (L.: Fr.) Fr. spreads in the litter by means of its rhizomorphs. It colonizes needles in autumn, soon after litter fall. Penetration of mycelium into needles occurs through stomata. Rhizomorphs and fruit bodies appear 1 year later, in summer and autumn, emerging from the needles by rupturing the epi- and hypo-dermis. In the first stage of colonization hyphae invade needle tissues in extracellular spaces and along vessels. During a second stage, parenchyma (cellulosic cell walls and residual cytoplasm) is bleached and destroyed. Lignified cell walls are degraded, in particular those of the epi- and hypo-dermis. Marasmius androsaceus activity is restricted to L and F1 litter, reaching a maximum after those of Thysanophora penicillioides (Roum.) Kendrick and Lophodermium piceae (Fuckl.) Höhn. Obvious differences are observed among needles colonized by these three different fungi.
Association of Trechispora alnicola with yellow ring disease of Poa pratensis
Authors: Wilkinson H. T.
Published: September 2008

Trechispora alnicola (Bourd. & Galz.) Liberia was associated with Poa pratensis L. roots and in the thatch layer of blue-grass sod. These plants had yellowed leaves. On thatch and culture medium, the fungus isolated from diseased plants produced hyaline mycelium typical of T. alnicola, and crystalline material. Conidia produced on thatch or on culture medium germinated by the production of a single germ tube. Basidia from basidiomata produced in nature were arranged in an effused manner; basidiospores were echinulate. This is the first report of T. alnicola associated with a member of the Graminae.
Ultrastructural characterization of an extracellular fibrillar sheath on cells of Ascocalyx abietina, the scleroderris canker agent of conifers
Authors: Benhamou Nicole , Ouellete G. B.
Published: September 2008

Morphology, ultrastructure, and some aspects of the chemical composition of a fibrillar sheath surrounding cells of the fungus Ascocalyx abietina (Lagerberg.) Schlaepfer-Bernhard were studied using electron microscopy and gold-labeled ligands. Although consistently present around all cells, the fibrillar matrix was found to vary greatly in morphology within the same isolate, depending apparently on age and (or) physiological conditions of the cells. Around cells considered younger, the sheath appeared always to be constituted of fibrillar masses that varied in size and shape but were delineated by a well-defined border. In contrast, cells expected to be older were generally bordered by a regular and uniform matrix composed of numerous intertwined fine fibrils, some being associated with small osmiophilic knobs. The presence of RNA in the denser layers of the sheath was revealed through gold complexes with either RNase A or RNase B. Continuity of portions of the sheath with similar material surrounding endocells or intact cells through gaps in the wall was frequently observed. This observation was considered as one of the possible explanations for the presence of RNA in the sheath. Association of sugars such as β-glucopyranosides and especially sialic acid with the extracellular matrix is, most probably, relevant to specific biological functions such as attachment to host cells, protection against unfavourable physical conditions and transport of cationic compounds. Peculiarities of this sheath produced by A. abietina contribute, therefore, to distinguish it from those described in other fungi.
Ultrastructural study and cytochemical investigation, by means of enzyme–gold complexes, of the fungus Ascocalyx abietina
Authors: Benhamou Nicole , Ouellette G. B.
Published: September 2008

The fungus Ascocalyx abietina (Lagerberg.) Schlaepfer-Bernhard, the scleroderris canker agent of conifers, is composed of a regularly septate mycelium, often branched at divergent angles. All fungal cells appear delimited by a thick wall surrounded by a dense fibrillar network. Peculiar ultrastructural characteristics of this fungus were observed, such as irregular nuclei with multishaped blebs and endoplasmic reticulum oriented in definite parallel arrays. Presence of single or multiple endocells was frequently observed. In some instances, gaps were present in the walls of enclosing cells where the cytoplasmic contents had escaped. Amylase, chitinase, β-galactosidase, lipase, and cellulose–gold complexes were used to localize various substances in A. abietina cells. With such complexes N-acetyl-D-glucosamine, β-galactosides, and lipids were detected in the cell walls, while glycogen deposits were found to occur in cytoplasmic electron-transparent bodies. The present work presents the ultrastructural features of A. abietina and adds to some of the cytochemical aspects recently reported.