bluuebunny/crossref_metadata_2025 huggingface dataset:
Culture and cytological development of Rhytidhysterium rufulum on citrus
Authors: Bezerra Jose L. , Kimbrough James W.
Published: April 2011

Cultural, cytological, and developmental aspects of the patellariaceous ascomycete Rhytidhysterium rufulum are investigated. A comparison of the ultrastructural features of the R. rufulum ascus with those of other loculoascomycetes is made. Meiosis and mitosis in the ascus and ascospores are not significantly different from those considered typical for most Ascomycetes. Ascospore delimitation begins after the ascus reaches its 16-nucleate stage. Differences in centrum development and hymenial configuration indicate that the Patellariaceae and Hysteriaceae may have to be placed in different orders. The centrum of R. rufulum appears unique and characteristic, not of the Pleospora type.
Growth responses of isolated ring traps of Dactylella doedycoides
Authors: Zachariah K.
Published: April 2011

Ring traps detached from axenic cultures of Dactylella doedycoides could be caused to inflate with chlorobutanol vapour, when placed upon cornmeal agar. Isolated uninflated rings produced a single, slowly growing hypha from the stalk scar; it later produced branches. Isolated inflated rings produced several rapidly growing hyphae from the inner curvatures of their three cells, mimicking the response elicited by trapped prey. Even after several hours of hyphal proliferation, isolated uninflated rings could be caused to inflate, and inflation increased the growth rate of the primary hypha.
Coronatine production in vitro and in vivo and its relation to symptom development in bacterial blight of soybean
Authors: Gnanamanickam S. S. , Starratt A. N. , Ward E. W. B.
Published: April 2011

Coronatine was detected in culture filtrates of 12 out of 19 pathogenic strains of Pseudomonas glycinea examined, but not in culture filtrates of strains of P. phaseolicola, P. syringae, or P. tabaci. A reversed-phase high-performance liquid chromatographic procedure was developed for coronatine quantitation. Generally, coronatine production by strains in culture correlated with their ability to induce systemic symptoms (chlorosis and stunting) in inoculated soybean plants. Application of purified preparations of coronatine to unifoliate leaves of soybean plants resulted in localized chlorosis, development of chlorosis in subsequently developing trifoliate leaves, and stunting of plant growth, similar to symptoms induced by infection. Coronatine was demonstrated in soybean leaves infected with P. glycinea but was not detected in healthy leaves. The results indicate that coronatine can play an important role in the development of symptoms of bacterial blight of soybean, but the demonstration that some pathogenic strains do not produce coronatine indicates that it may not be essential for pathogenicity.
Mallomonas parvula sp. nov. and Mallomonas retifera sp. nov. (Chrysophyceae, Synuraceae) from South Chile
Authors: Dürrschmidt Monika
Published: April 2011

Two new species of the unicellular genus Mallomonas, M. parvula sp. nov. and M. retifera sp. nov., were found in freshwater ponds in the vicinity of Valdivia, South Chile. Scales and bristles of the silica armour have been studied by means of scanning and transmission electron microscopy.
Interactive patterns of methyl mercury toxicity in nuclear and cell division of apical meristems of Elodea densa at low concentrations and long-term exposures in vivo
Authors: Czuba M. , Mortimer D. C.
Published: April 2011

Elodea densa plants continuously exposed to low levels of methylmercury (7.5 × 10−10 to 7.5 × 10−8 M) in a flowing water system over a 25-day period concentrated methylmercury in young tissues. Toxicity effects in apical meristems were not linear with dose and time but were interactive in response. Microscopic studies of plants treated at 7.5 × 10−10 M showed a predominance of "spaghetti" prophases, a gradual inhibition of mitosis, and imbalance of mitotic stages. Higher concentrations of methylmercury produced different effects: bi- and multi-nucleate cells, polyploidy, aneuploidy, and altered or incomplete cell walls. At the highest concentrations (7.5 × 10−8 M) total pycnosis developed in the apex within 11 days, followed by a disintegration of nuclear and cell contents. Demethylation in tissues was directly related to methylmercury concentrations in the tissues and to tissue age.
Formation of chloroplast pigments in a temperature-sensitive, virescent mutant of maize
Authors: Hopkins W. G.
Published: April 2011

Pigment levels and greening responses have been examined in a temperature-sensitive virescent 16 mutant of maize with a temperature threshold of 25 °C for greening. Expansion of tissue at 20 °C leads to a reduction of protochlorophyll level as well as carotenoids and chlorophyll. Seedlings will not green at 20 °C under low-intensity intermittent or continuous light. Chlorophyll is formed at 20 °C in the light following etiolation at 28 °C. These results suggest that absence of chlorophyll in the virescent seedling at temperatures below the threshold is not due to loss of the protective function of carotenoids and consequent photooxidation of chlorophyll.
Presymptomatic multiplication of Xanthomonas campestris pv. vesicatoria on the surface of pepper leaves
Authors: Sharon Edna , Bashan Yoav , Okon Yaacov , Henis Yigal
Published: April 2011

Xanthomonas vesicatoria infection of pepper leaves was monitored by scanning electron and light microscopy. During incubation the bacteria became located in the intercellular spaces between the mesophyll cells. The primary infection sites were the vein areas. Xanthomonas vesicatoria reach high population levels on the leaf surface but usually not in the stomata. Necrosis was first observed microscopically 120 h after inoculation near the leaf veins. Bacteria were detected in infected tissue but not in necrotic tissue.
Fine structure of the thraustochytrid Ulkenia amoeboidea. II. The amoeboid stage and formation of zoospores
Authors: Kumar S. Raghu
Published: April 2011

In the thraustochytrid Ulkenia amoeboidea (Bahnweg & Sparrow) Gaertner the contents of the mature vegetative thallus escape from the cell wall in the form of a limax cell. The limax cell is covered by a layer of scales and possesses a nucleus, a paranuclear body, Golgi bodies, mitochondria, bands of smooth endoplasmic reticulum, vacuoles, multivesicular bodies, and cisternae with filamentous contents. The posterior end is filled with smooth endoplasmic reticulum and fusiform vesicles. The anterior end is organelle free and filled with cytoplasm with free ribosomes. Subspherical dense bodies, bounded by a single membrane, are present. The limax cell rounds up prior to mitosis and the Golgi bodies increase in number. During mitosis, the nuclear membrane breaks down totally. Chromosomes are not well defined. Spindle microtubules arise from the centriole and enter the nucleus. After nuclear division, the nuclear envelope is reformed. Cytokinesis is by cleavage into two cells, accompanied by formation of microtubules along the cleavage furrows. The zoospore possesses a nucleus, a paranuclear body, mitochondria, vesicles with presumptive mastigonemes and kinetosome rootlet microtubules and they are covered by a layer of scales. An electron-dense granule and two peripheral thickenings are present within the lumen of the kinetosome.
The organization of microtubules in guard cell mother cells of Zea mays
Authors: Galatis B.
Published: April 2011

The cortical interphase microtubules of the guard cell mother cells (GMCs) of Zea mays form a well-grouped band (interphase microtubule band, IMB) lining the midregion of the lateral and periclinal walls, which are the only expanding walls during interphase. In advanced interphase GMCs, another population of microtubules emerge from the cortical cytoplasm of the midregion of the periclinal walls, entering deep into the cytoplasm. Elongated proplastids converge on the above cortical regions, possibly aligned by the microtubules with which they are associated.The IMB depolymerizes prior to mitosis and a preprophase microtubule band (PMB) is organized adjacent to the proximal, distal, and periclinal walls. In transverse sections the preprophase – early prophase nucleus appears slightly elliptical or spindle-shaped, sometimes exhibiting acute angular profiles at its poles. Extranuclear microtubules closely juxtaposed with the nuclear envelope converge on the "poles" of the nucleus, close to the regions of the PMB adjacent to the periclinal walls. The observations suggest a local interplay between the PMB and (or) the PMB cytoplasmic site on the one hand and the nuclear envelope and (or) the extranuclear microtubules on the other.The microtubules of both bands lining the periclinal walls and the sites of their junctions with the anticlinal ones are more closely grouped than those running along the anticlinal walls, and they exhibit intimate associations with numerous dictyosome vesicles. This preferential gathering of dictyosome vesicles, among others, possibly manifests a mechanism promoting the thickening of the expanding regions of the above walls.The inhibition of the symmetrical divisions of the GMCs by a continuous colchicine treatment leads to the formation of epidermal idioblasts possessing some of the characteristidcs of the guard cells. Furthermore, in the absence of microtubules, local wall thickenings are deposited in the middle of the periclinal walls and at their junctions with the anticlinal ones.From the observations it seems likely that guard cell differentiation commences in GMC, and that the cortical cytoplasm and (or) the plasmalemma of the midregion and the edges of the periclinal walls of the GMC possess some factor(s) favouring their preferential thickening. Cortical microtubule organizing centres (MTOCs) appear to be localized in these regions and activated in a programmed fashion.
Sea ice diatoms from Manitounuk Sound, southeastern Hudson Bay (Quebec, Canada). I. Family Naviculaceae
Authors: Poulin Michel , Cardinal André
Published: April 2011

More than 110 species of diatoms were identified from samples collected from Manitounuk Sound, Hudson Bay, in 1978. We presently deal with six genera, belonging to the family Naviculaceae; Diploneis (3 taxa), Gyrosigma (3 taxa), Pinnularia (18 taxa), Pleurosigma (4 taxa), Stauroneis (1 taxon), and Stenoneis (1 taxon).All the species were reevaluated and complete illustrated descriptions, biometric data, and worldwide distributions are given. Two new species and two varieties are described and a new combination is proposed.
Slime plugs do not inhibit surge flow in sieve tubes
Authors: Barclay Gregor F.
Published: April 2011

Slime plugs, composed largely of P protein, on sieve plates in phloem of Heracleum mantegazzianum L. and Heracleum sphondylium Somm. and Lev. do not seem to be effective in preventing surge flow caused by loss of turgor, therefore calling into question the role of slime plugs in phloem.
A multivariate approach to the problem of decline in vigour of Ammophila
Authors: Eldred R. A. , Maun M. A.
Published: April 2011

On stabilized sand dunes where sand deposition has ceased, Ammophila breviligulata Fern, declines in vigour, flowers less prolifically, and often remains vegetative. Many explanations for this decline have been put forward in the past. This study has chosen a comparative multivariate approach to address the problem.For this objective, 59 random 1-m2 quadrats were laid out over a young sand dune system near Port Franks, Ontario, on the southeastern shore of Lake Huron. In each plot six environmental variables (sand deposition, sand flux, number of annual species, number of perennial species, soil temperature, and the depth of the roots) and four plant characters of A. breviligulata (flowering percentage, shoot biomass, vegetative reproduction rate, and shoot density) were recorded. The resulting data matrices were subjected to canonical correlation analysis.The results revealed that, of the environmental variables, both sand deposition and root depth had strong relationships with shoot biomass (positive), flowering (positive), and vegetative reproduction rate (negative). Competition from annuals and perennials appeared a secondary factor in the decline of A. breviligulata. Flowering was rare in high shoot density sites with low levels of sand deposition and in low density sites with greater number of annual species.
Clathroconium, a new helicosporous hyphomycete genus from spiders
Authors: Samson Robert A. , Evans Harry C.
Published: April 2011

Clathroconium arachnicola gen. and sp. nov. is described from a spider, collected on a cocoa leaf in Ghana. The fungus is characterized by yellow–brown, solitary, clathroid conidia.
3-Nitropropionic acid and 3-nitro-1-propanol in species of Astragalus
Authors: Williams M. C.
Published: April 2011

Leaves of nitro-bearing species of Astragalus collected from North American and European herbaria were analyzed for types of toxic aliphatic nitro compounds. The nitro compounds were extracted and hydrolized to 3-nitropropionic acid (3-NPA) or 3-nitro-1-propanol (3-NPOH) and identified by thin-layer chromatography. Species of Astragalus were chemotaxonomically related within taxonomic sections relative to synthesis of 3-NPA or 3-NPOH. All species of Astragalus in 19 Old World and 21 North American taxonomic sections synthesized nitro compounds that yielded 3-NPA upon hydrolysis while 3-NPOH was found upon hydrolysis in species of 5 Old World and 10 North American taxonomic sections. Therefore, one could predict the presence of 3-NPA or 3-NPOH in species within entire taxonomic sections based on the analysis of one or two species within a section. South American species yielded predominately 3-NPOH. These data are useful for taxonomic classification of Astragalus, for preventing international exchange of germplasm of poisonous species of Astragalus, and for diagnostic purposes in livestock poisoning.
The taxonomy of Lobelia × speciosa s.l. and its parental species, L. siphilitica and L. cardinalis s.l. (Lobeliaceae)
Authors: Bowden Wray M.
Published: April 2011

Nomenclatural proposals are Lobelia cardinalis L. subsp. cardinalis var. cardinalis f. hispidula (E. Wimmer) Bowden; L. cardinalis L. subsp. graminea (Lam.) McVaugh var. propinqua (Paxton) Bowden f. × propinqua (= f. cordigera × f. splendens), var. propinqua f. cordigera (Cav.) Bowden, and var. propinqua f. splendens (Humb. & Bonpl. ex. Willd.) Bowden; L. × speciosa Sweet nm. schneckii Bowden (= L. siphilitica L. var. siphilitica × L. cardinalis L. var. cardinalis); and L. × speciosa Sweet nm. occidentalis Bowden (= L. siphilitica L. var. ludoviciana A.DC. × L. cardinalis L. subsp. graminea (Lam.) McVaugh var. phyllostachya (Engelm.) McVaugh). During the past 40 years, a complex group of tetraploid hybrids has been developed by the author by crossing, selfing, and backcrossing and with much selection of superior cultivars. The ancestral plants of these tetraploid clonal hybrids were L. siphilitica var. siphilitica, L. cardinalis subsp. cardinalis var. cardinalis, and L. cardinalis subsp. graminea var. propinqua cv. Queen Victoria and cv. Illumination. It is proposed to name the clonal hybrids: L. × speciosa Sweet (Canadian Tetraploid group) cv. Brightness, cv. Oakes Ames, etc.
Vegetative bud development and the time and method of cone initiation in subalpine fir (Abies lasiocarpa)
Authors: Owens John N. , Singh Hardev
Published: April 2011

Vegetative terminal and axillary bud development and the time and method of cone initiation and cone bud development are described for Abies lasiocarpa (Hook.) Nutt.Cell divisions began in vegetative buds early in April. A brief period of apical enlargement was followed by bud-scale initiation for 10 weeks. Buds were initiated in the axils of some leaf primordia about the time of vegetative bud burst, 1 month after vegetative bud dormancy ended. All buds completed bud-scale initiation by the end of June, which coincided with the end of the rapid phase of lateral shoot elongation. This was followed by a 2-week period of bud differentiation, during which time few primordia were initiated, apical size increased, and apical shape and zonation changed more in reproductive than in vegetative apices. Leaf and bract initiation began by mid-July and continued until mid-October, when vegetative and seed-cone buds became dormant. Microsporophyll initiation began earlier and was nearly completed by the end of July; pollen-cone buds became dormant in mid-September.The number of cone buds is determined by the proportion of axillary bud primordia that fully developed and the pathway along which they developed. Potential seed-cone buds may become latent but more commonly differentiate into vegetative buds of low vigor. Potential pollen-cone buds frequently become latent but have not been observed to differentiate into vegetative buds. The position of the axillary bud on the shoot and of the shoot in the tree strongly influences axillary bud development in Abies.
Shedding of ephemeral roots in gymnosperms
Authors: Tippett Joanna T.
Published: April 2011

Periderm formation across the base of short lateral roots facilitated their shedding in balsam fir (Abies balsamea (L.) Mill.), white pine (Pinus strobus L.), and hemlock (Tsuga canadensis (L.) Carr.). The periderm originated either from the pericycle, in line with normal subendodermal development, or after dedifferentiation and redifferentiation of cells across existing vascular tissues near the base of senescent short roots. Consequently the short roots were either shed neatly along with the cortex of the parent roots or they were isolated by a new layer of periderm linking existing parent-root periderm, analogous to protective tissue formation beneath petiole abscission zones. Short roots were not always isolated by periderm prior to detachment, but periderm still formed at the base of the root stubs and eventually became the superficial protective layer of the root scars.
Cytological study of palisade development in the seed coat of Candle canola
Authors: Caeseele L. Van , Mills J. T. , Sumner M. , Gillespie R.
Published: April 2011

The differentiation of the palisade layer in the developing seed of Brassica campestris L. cv. Candle canola was studied from pollination to maturity. The palisade was derived from the innermost cell layer of the outer integument and was sandwiched between several layers of crushed parenchyma. The secondary thickening of the radial and inner tangential walls of all palisade cells was initiated about 5 days after pollination and continued for about 20 days. Vesicles and similar-sized invaginations of the plasmalemma were present in the cytoplasm. An increased number of dictyosomes and endoplasmic reticulum associated with paracrystalline bodies were also observed. The palisade cytoplasm appeared normal in unfertilized ovules and seeds 5 days after pollination but degenerated as seeds neared maturity. Outer portions of the radial walls had no secondary thickening and collapsed to form characteristic folds when seen in radial section. Lamellations were visible in areas where secondary thickening was heavily deposited. Remnants of plasmodesmata were present in the lamellations and traversed the primary walls, but were not present in areas of most recent secondary wall deposition. Cross sections showed these remnants were filled with an electron-dense material. The inner tangential wall of the palisade and the outer tangential wall of the parenchymal cell directly below appeared to fuse forming a single continuous layer.
The ultrastructure of Endothia parasitica. Comparison of a virulent with a hypovirulent isolate
Authors: Newhouse Joseph R. , Hoch Harvey C. , MacDonald William L.
Published: April 2011

Hyphae of virulent (v) Endothia parasitica isolate 16-15-1 (West Virginia) and hypovirulent (hv) isolate Ep-4 (France) were preserved by freeze-substitution, embedded, and longitudinally sectioned to describe and compare their subcellular structure. General ultrastructural features of both were similar. Apical vesicles and uncoated microvesicles were common constituents of the extreme hyphal apex. Abundant membranous material also was seen in this region in some tip sections of hv isolate Ep-4. Filasomes were located along the lateral hyphal wall just behind the apex, and one was observed to be fused with the plasmalemma. Golgi cisternae were numerous in the tip area and appeared very flat and fenestrated, and often were closely associated with mitochondria. Components of the vacuole system were variously shaped, totally electron dense in young hyphae, and lighter with discernible inclusions in older hyphae. Spherical, membrane-bounded viruslike particles (VLPs), 51–78 nm in diameter, were observed in tip cells of hv isolate Ep-4, but not v isolate 16-15-1. The VLPs may be responsible for hypovirulence in the Ep-4 isolate. Endoplasmic reticulum cisternae contact in hyphae of Ep-4 may have been related to the presence of VLPs.
Heat tolerance of rhizomes of several understory species
Authors: Flinn Marguerite A. , Pringle Joan K.
Published: April 2011

Rhizomes of eight understory species: Gaultheria procumbens, Maianthemum canadense, Vaccinium angustifolium, Cornus canadensis, Pteridium aquilinum, Kalmia angustifolia, Chamaedaphne calyculata, and Rhododendron canadense were subjected to treatments of 45, 50, 55 and 60 °C for 5 min in a water bath. Selection of these species for study was based on differences in the depth of the rhizomes, in habitat, and in rhizome morphology. Samples were collected from study sites located near Halifax, in the Nova Scotia Acadian Forest region.Maximum shoot growth occurred at different temperatures for the various species: 45 °C for Cornus canadensis; 50 °C for Chamaedaphne calyculata, R. canadense, and V. angustifolium; 55 °C for G. procumbens and M. canadense. Death occurred at or below 60 °C for most species. For comparative purposes, a temperature tolerance index (TTI) was calculated for each species. The TTI indicated that R. canadense and V. angustifolium showed the greatest tolerance to higher temperatures and that K. angustifolia and P. aquilinum showed the least tolerance. Mean shoot number increased significantly following spring treatments for all species except for Cornus canadensis which showed greater increase following autumn treatments.
Étude du polymorphisme enzymatique d'une population de pleurotes des ombellifères : Pleurotus eryngii (Tournus, France)
Authors: Boisselier-Dubayle Marie-Catherine
Published: April 2011

Electrophoretic separations followed by revelations of esterase, aminopeptidase, and phosphatase activities were performed on a population of Pleurotus eryngii (Tournus: Saône valley, France). Electrophoresis on controlled dicaryotic mycelia and their haploid components was used as a convenient means to study the genetic determination of some esterase and phosphatase isoenzymes. The electrophoretic patterns obtained from original isolates (wild dicaryons) show little variability, but internal variations are revealed. These variations allowed for a characterization of four genotypically different individual groups. This analytical method seems to give some interesting data, useful for taxonomic studies.
Scanning ultrastructural ontogeny of apothecia in the operculate discomycete Trichophaea abundans
Authors: Turnau Katarzyna
Published: April 2011

Morphogenesis of apothecia in Trichophaea abundans (Karst.) Boud., a homothallic operculate discomycete (Pezizales, Pyronemataceae sensu Korf 1973), was investigated with the scanning electron microscope from initiation of ascogonial coils until ascospore discharge. Since the incipient paraphyses are enclosed by the overarching ectal excipular margin in the early phase, hymenial development is classified as cleistohymenial.
Cellular differentiation in small clumps of Lotus corniculatus callus
Authors: Howarth Melanie J. , Peterson R. L. , Tomes D. T.
Published: April 2011

Lotus callus cultures were studied in an attempt to determine, at the cellular and subcellular levels, what morphological changes precede and accompany differentiation. Small clumps of homogenized callus were plated onto a medium containing benzyladenine, which was known to induce differentiation in this system. Initially callus was yellowish and consisted of large, vacuolated cells with deposits of starch. Marked changes occurred in these cells; peripheral and endogenous meristematic areas were initiated giving rise to shoots and either groups of tracheary elements or roots, respectively. Roots developed within 5 day s, while shoot apical meristems with leaf primordia formed by day 9. Many of the cells surrounding meristematic areas developed suberin lamellae in their walls, while others, both within and on the periphery of meristematic areas, accumulated phenolic substances. Cells within meristematic areas had large nuclei with prominent nucleoli, plastids with thylakoids but little or no starch, many mitochondria, and dictyosomes. Morphological observations tend to support the view that physiological isolation of tissue may precede differentiation.
Interaction of light quality and temperature on the vegetative reversion of conidiophores in Alternaria cichorii
Authors: Vakalounakis Demetrios J. , Christias Christos , Malathrakis Nicholaos E.
Published: April 2011

The development of the conidiophores of the fungus Alternaria cichorii Nattrass was induced by near ultraviolet irradiation (< 340 nm). Temperatures above 25 °C induced a vegetative reversion of conidiophores to sterile hyphae. This reversion was more intense under the influence of blue light (390–530 nm). The extent of vegetative regrowth was proportional to the incubation temperature: the higher the temperature the longer the vegetative regrowth of conidiophores.
Local variation in seeds of ponderosa pine
Authors: Ager Alan A. , Stettler R. F.
Published: April 2011

Variation in seed morphology among populations of ponderosa pine growing in south central Oregon was examined. A total of nine populations was sampled from a range of elevations within each of two distinct soil types: basalt residuals derived from Pliocene basalt flows and wind-deposited pumice originating from the eruption of Mt. Mazama 7600 years ago. Overall, an unusually diverse array of seed morphology was encountered. Slight but significant differences in seed shape and color were present between populations from the two soil types. Except for seed weight, no significant differences were found between populations within soils. Variation in seed weight was negatively correlated with seed source moisture as measured by elevation. For all traits studied, variance components for populations and soils were relatively minor, the within-population component accounting for a major portion of the total variation. Hypotheses are offered to explain the high levels of within-population diversity in seed traits as an adaptation to a spatially heterogeneous environment, as well as a defense against the foraging behavior of seed predators. Also, the possible adaptive significance of the observed variation in seed traits is discussed in relation to seedbed properties of the respective soils.
The heterobasidiomycetous yeast genus Leucosporidium in an area of temperate climate
Authors: Summerbell Richard C.
Published: April 2011

A wide range of habitats in and near southern British Columbia was sampled for the presence of Leucosporidium spp. Leucosporidium scottii, the only species capable of growth at mesic temperatures, occurred abundantly on marine substrates. The thalli of phaeophyte algae yielded particularly large numbers of isolates, but only in the colder months of the year. Leucosporidium scottii was found less frequently in terrestrial or freshwater habitats but was a major component of the yeast mycobiota of organic materials decaying in cold moist soils. The remaining five known species of Leucosporidium were not found. Genetic studies revealed that the tetrapolar mating system of L. scottii is characterized by the presence of multiple alleles at the A locus. The B locus appears to be biallelic.
Action des rayons gamma du Cobalt 60 sur la teneur en acides nucléiques et l'histogenèse des tissus de tubercule de topinambour cultivés in vitro
Authors: Schaeverbeke-Sacré Janine , Matheron Béatrice
Published: April 2011

DNA and RNA contents are studied in Jerusalem artichoke tuber explants cultured in vitro after gamma irradiation (0–5 × 105 rads (1 rad = 10 mGy)). The lower part of the explants is stimulated as soon as in contact with the medium. This stimulated area is still able to synthesize DNA and RNA up to 104 rads. An histological and cytological study shows that tissue neoformations can be observed up to 6000 rads in this outer area and that gamma rays seem to keep the cells in a "premitotic" state for a longer or shorter period according to the applied radiation dose.
Photosynthesis and respiration of feather mosses fumigated at different hydration levels with SO2
Authors: Winner William E. , Bewley J. Derek
Published: April 2011

Fumigation with SO2 of the three feather mosses Pleurozium schreberi, Hylocomium splendens, and Ptilium crista-castrensis results in an immediate decline in their rate of photosynthesis but has no effect upon respiration. Pleurozium schreberi is the most sensitive of the three species, even though they all take up the same amount of SO2. Thus, the feather moss species appear to have similar degrees of SO2 avoidance (uptake) but dissimilar degrees of SO2 tolerance. With increasing desiccation, respiration declines equally in all three species, but photosynthesis declines most rapidly for P. schreberi. The immediate effects of SO2 upon photosynthesis of water-limited and of fully hydrated feather mosses are similar, but after a 24-h recovery period in an SO2-free environment photosynthesis remains impaired only in those mosses fumigated in the fully hydrated state. This probably is related to the larger amounts of SO2 absorbed by hydrated mosses.
Localisation des activités de la p-nitrophénylphosphatase et de la phosphatase alcaline dans les cellules de transfert du noeud cotylédonaire du pois nain
Authors: Nougarède A. , Landré P. , Rembur J.
Published: April 2011

The ultrastructural localization of the K+-dependent nitrophenylphosphatase (NPPase) and alkaline phosphatase (ALPase) activities were determined in the transfer cells of the pea cotyledonary node. These two types of activities were generally associated and located essentially on the plasma membrane. NPPase and ALPase activities were also detected along the nuclear membrane of the xylem and phloem transfer cells and along the endoplasmic reticulum profiles (internal face) of phloem transfer cells. Mitochondrial NNPase activity was confined to the outer membrane and cristae. The partial inhibition of the NPPase reaction products by L-p-bromotetramisole and cysteine, the weak reaction observed after deletion of K+, and the suppression of the reaction in the presence of L-p-bromotetramisole are best explained by the concomitant activity of a K+-dependent NPPase and of an ALPase partially inhibited by K+. On the basis of sensitivity to inhibitors, two plasma membrane ALPase isoenzymes were detected. One, extramembranous, was bromotetramisole and cysteine insensitive but inhibited by L-phenylalanine; the other, intramembranous, was bromotetramisole and cysteine sensitive, but insensitive to L-phenylalanine. The other sites of ALPase activities were substantially inhibited by all treatments.
Ascus and ascospore development in Eleutherascus peruvianus. 2. Nuclear cytology and early ascus ontogeny
Authors: Steffens W. L. , Jones J. P.
Published: April 2011

A study was undertaken of the cytological events leading to ascus initiation through delimitation of the ascospores prior to spore wall deposition in Eleutherascus peruvianus Huang. As revealed by Giemsa staining, nuclei in asci which are derived from croziers in the classical manner undergo the three divisions, with each division occurring in a different plane. The result is a globose ascus with eight nuclei displaying a high degree of internal order with respect to the arrangement of the ascospores. Electron microscopy reveals that subsequent to the final nuclear division, the ascus becomes filled with several elongate segments of double membrane underlying the ascus plasmalemma. These membrane segments appear to result from marked focal invaginations of the ascus plasmalemma and ultimately fuse together to form the ascus vesicle. Occasional observations of nuclei outside of the ascus vesicle membranes are believed to account for the often observed phenomenon of asci with odd numbers of ascospores. The significance of these findings relative to those for some close allies is discussed.
Confistulina, the anamorph of Fistulina hepatica
Authors: Stalpers Joost A. , Vlug Ijda
Published: April 2011

The anamorph of Fistulina hepatica is described in detail and a new genus, Confistulina, is proposed to accommodate it. A relationship to Ellula is suggested, followed by a more general discussion on anamorph–teleomorph homologies.
15N isotope dilution to quantify dinitrogen (N2) fixation associated with Canadian and Brazilian wheat
Authors: Rennie R. J. , deFreitas J. R. , Ruschel A. P. , Vose P. V.
Published: April 2011

Putative dinitrogen (N2) fixation associated with wheat (Triticum aestivum L. emend. Thell) has been studied using acetylene reduction and nonisotopic N-balance techniques. Absolute proof of N2 fixation using 15N2 (gas) or 15N isotope dilution procedures has not been reported. This paper presents the first use of the 15N isotope dilution technique to determine in wheat the percent plant N derived from associated N2 fixation. Although inoculation with either Bacillus polymyxa (C-11-25) or Azospirillum brasilense (ATCC 29145) resulted in no significant increase in total plant N in nine Canadian and one Brazilian wheat varieties, isotopic N data showed that N2 fixation did occur. The amounts of plant N derived from atmosphere, fertilizer, and soil varied. A high degree of plant–bacterial specificity existed. In several instances, the substitution of a single chromosome pair in the wheat regulated the amount of N2 fixed. The agreement between this 15N isotope experiment and two previous nonisotopic experiments suggests that the trait supporting N2 fixation in wheat may be consistently expressed in the varietal lines.
The taxonomy of the Carex pensylvanica complex (Cyperaceae) in North America
Authors: Crins William J. , Ball Peter W.
Published: April 2011

The Carex pensylvanica complex consists of four North American taxa. Morphological variation patterns within the complex were examined using principal-components analysis and discriminant-functions analysis. These results indicate that two eastern species, C. lucorum Willdenow ex Link, and C. pensylvanica Lamarck, and one western species, C. inops Bailey, should be recognized. The latter species comprises two subspecies, C. inops subsp. inops and C. inops subsp. heliophila (Mackenzie) Crins, comb. nov. Cytological and geographical evidence lend support to this classification. A key and distribution maps for the taxa are provided.
Presence and development of lignotubers in shrubs of the Chilean matorral
Authors: Montenegro Gloria , Avila Guacolda , Schatte Peter
Published: April 2011

The development of lignotubers was analyzed in seedlings of representative shrub species of the matorral in central Chile. The lignotuber is evident 3 months after germination in Cryptocarya alba and 4–5 months after germination in Colliguaya odorifera, Satureja gilliesii, and Lithraea caustica. Top removal in adult specimens soon produced formation of shoots as a result of the activation of the root-crown buds. The leaf area growth rates of shoots arising from lignotubers are significantly higher than those of seedlings and normally growing shrubs. The adaptive significance of lignotubers in matorral shrubs is discussed.
Pathogenicity of five Verticicladiella species to lodgepole pine
Authors: Bertagnole Catherine L. , Woo John Y. , Partridge Arthur D.
Published: April 2011

Pathogenicity of Verticicladiella procera, V. penicillata, V. abietina, V. serpens, and V. antibiotica was tested in live roots of field-grown lodgepole pine. The first four species produced resinous lesions varying in size according to species; expansion rates in root wood matched respective growth rates in culture. In root xylem, V. penicillata grew fastest, V. procera nearly as rapidly, producing lesions of various sizes, and V. abietina and V. serpens, slowest. Verticicladiella antibiotica was saprophytic. Diverse morphological structures, characterizing each species, were found in root wood. No dematiaceous hyphae occurred in roots inoculated with V. procera. However, fine hyaline hyphae, often anastomosing, penetrated axial tracheids and ray parenchyma. Verticicladiella penicillata produced abundant hyaline hyphae and few dematiaceous hyphae. Verticicladiella abietina produced buds on dematiaceous, septate, sporogenous hyphae in axial tracheids and ray parenchyma; hyaline hyphae also penetrated those cells. Verticicladiella serpens produced hyaline and dematiaceous pleomorphic structures from sporogenous hyphae in xylem cells. Results support speciation of five Verticicladiella isolates and demonstrate their pathogenicity to lodgepole pine.
The taxonomic significance of seedling morphology in Agalinis (Scrophulariaceae)
Authors: Canne Judith M.
Published: April 2011

Observations on seedlings of 18 species of Agalinis Raf. indicate a diversity of seedling types based on variation in shape and size of cotyledons, presence or absence of hairs on the hypocotyls, and types of trichomes present on the adaxial surface of cotyledons. Three major trichome types occur repeatedly among numerous species, while other hair types are restricted to one or a few taxa. Seedling features are often distinctive at the species level and correlate well with data from other sources with regard to sectional and subsectional placement of species within the genus.
Senescence, turion development, and turion germination in nitrate- and sulfate-deficient Spirodela polyrhiza. Relationships between nutrient availability and exogenous cytokinins
Authors: Malek Ladislav , Cossins Edwin A.
Published: April 2011

Senescence, turion development, and turion germination were investigated in NO3-deficient (1/20 Hoagland's nitrate) and SO4-deficient (1/200 Hoagland's sulfate) Spirodela polyrhiza L. (Schleiden) grown in continuous light at 25 °C. These deficiencies resulted in frond senescence and the development of turions. Supplements of nitrate or sulfate reversed parent frond senescence and initiated frond growth in primordia not committed to turion development. Amino acids normally derived from nitrate and sulfate partially reversed the deficiency-induced symptoms of senescence. Turions formed in NO3-deficient media germinated in media containing 1 mM nitrate, glutamate, aspartate, and glycine, respectively, providing dormancy was broken by osmotic treatment. Similarly, turions formed in SO4-deficient media required 1 mM sulfate or methionine for germination. Exogenous isopentenyl adenine and benzyl adenine (5 or 0.5 mg/L) were able to overcome turion dormancy and stimulated germination in the presence or absence of exogenous salts. In addition, these cytokinins prevented turion development in NO3- and SO4-deficient cultures, although their effect on senescence, as judged by chlorophyll levels, was minimal. Analysis of protein-bound amino acids in control and NO3- and SO4-deficient plants showed that deficient fronds contain significantly lower levels especially of the sulfur amino acids. The concentration of free amino acids decreased in NO3-deficient fronds but increased, relative to controls, in SO4 deficiency.
Taxonomy of Phaeangium lefebvrei, a desert truffle eaten by birds
Authors: Alsheikh Abdulmagid M. , Trappe James M.
Published: April 2011

The desert truffle genus Phaeangium Patouillard, synonymized with Picoa by R. Maire, is resurrected. Phaeangium has ornamented spores at maturity and a tomentose peridium, whereas Picoa has smooth spores and no tomentum. Phaeangium and its single species, P. lefebvrei, are redescribed and placed in the family Pyronemataceae, tribe Mycolachneae. In 1978 the senior author collected quantities of a small truffle in several desert habitats in Kuwait. We determined it to be Phaeangium lefebvrei Pat. (Picoa lefebvrei (Pat.) Maire). These collections provided excellent material to redescribe this species and to reexamine its hitherto disputed generic assignment. This truffle fruits from January to April in North Africa and the Middle East during years of adequate rainfall. In Kuwait it is confined to gypsiferous and calcareous, gravelly deserts, where it is scratched out and eaten by several species of migrating birds.
Production in vitro de périthèces du Nectria ditissima, agent du chancre du hêtre (Fagus sylvatica). I. Influence du milieu de culture et de la température. Application à la réalisation d'infections artificielles du hêtre
Authors: Dehorter B. , Perrin R.
Published: April 2011

not available
Chromosome numbers in Boykinia and allies (Saxifragaceae)
Authors: Gornall Richard J. , Bohm Bruce A. , Taylor Roy L.
Published: April 2011

Chromosome numbers are reported for the first time for Boykinia intermedia (2n = 14), B. major (2n = 28), Peltoboykinia watanabei (2n = 22), and Suksdorfia (= Hemieva) ranunculifolia (2n = 14). Additional counts are provided for eight other species of Boykinia (including Telesonix), Peltoboykinia, Suksdorfia, and Bolandra. Previous literature reports are reviewed and some errors pointed out. Chromosome numbers do little to resolve the problem of generic limits, with the exception of supporting the segregation of Peltoboykinia. They do, however, support the recognition of Boykinia intermedia as a species distinct from B. major.
Effects of colored light on the growth and metabolism of Fucus embryos and apices in culture
Authors: McLachlan J. , Bidwell R. G. S.
Published: April 2011

Embryos and apical segments of mature thalli of species of Fucus were grown in laboratory culture under fluorescent light. Various Plexiglas filters were used to provide light of different spectral composition. Some wavelengths were more conducive of growth and development than others. However, light with wavelength about 575 to 625 nm was strongly deleterious to all plants and lethal within 4 to 6 weeks to embryos. This effect was not the result of insufficient light, because similar plant material survived for long periods in darkness without ill effects. The deleterious effect could be completely reversed by the addition of longer or shorter wavelength light. Products of photosynthesis in 14CO2 were affected by the light colors that affected growth. When growth was reduced, mannitol, the major alcohol-soluble product of photosynthesis, decreased and the production of dilute HCl soluble material increased. The addition of longer or shorter wavelength light reversed the effects caused by deleterious wavelengths.
Morphometric relationships in Hordeum vulgare (Triticeae, Poaceae). I. H. spontaneum
Authors: Baum Bernard R. , Bailey L. Grant
Published: April 2011

This paper is the first contribution to a reexamination of Hordeum vulgare (sensu lato). It sets forth and defines the characters which formed the basis of our studies, and reports the results of our morphometric analyses of the morph H. spontaneum C. Koch. An evaluation of previous taxonomic treatments of infraspecific variation was carried out. Åberg's (1940. Symb. Bot. Upsal. 4(2): 1–156) varieties are rejected on the basis of inadequate criteria. Nabelek's (1929. Wiss. Arch. Landwirtsch. Abt. A, 1: 804–807) varieties, though well-defined, are not supported by the results of our discriminant analyses. It is concluded that, although the spontaneum morph is highly variable, it does not lend itself to the recognition of infraspecific segregates.
A comparison of preparative techniques for the examination of the external morphology of fungal material with the scanning electron microscope
Authors: Read N. D. , Porter R. , Beckett A.
Published: April 2011

The external morphology of the ostiolar pore region in Sordaria humana was examined with the scanning electron microscope (SEM) in the vacuum-dried, air-dried, critical-point-dried, freeze-dried, partially frozen–hydrated, and fully frozen–hydrated states after a range of pretreatments. The appearance of this structure was dependent on the method of preparation and the operational conditions employed within the microscope. All the preparative procedures used produced artifacts. These secondary changes varied according to the method of preparation and the nature of the specimen (or part thereof). Common artifacts arising from freezing damage, slow chemical fixation, differential conformational changes, ice recrystallization, water condensation, and beam damage have been characterized. The examination of material in the frozen–hydrated condition is the closest we can get to viewing its structure under the SEM in a state of "suspended animation."
A comparative study of the structure of cell wall surfaces: air spaces in leaves are exceptional in having exposed microfibrils
Authors: Willison J. H. M. , Pearce R. S.
Published: April 2011

The study compares the appearance of cell wall outer surfaces adjacent to air spaces in cereal leaves (wheat and rye) with other cell wall surfaces (root hair, water-filled root intercellular space, root gas space) using replica specimen-preparation techniques for electron microscopy, particularly freeze-etching. While all other cell wall outer surfaces are heavily impregnated with materials which fill intermicrofibrillar interstices, those associated with cereal leaf air spaces are impregnated to a lesser extent and are described here as "open." This openness appears to continue at least into the centre (in the radial sense) of the cell wall. There was some evidence for puddling of water at certain sites. The results are discussed in terms of their significance for understanding the nature of leaf air-space cell wall surfaces (it is argued that there is no "cuticle" equivalent to that covering the leaf outer surface), and by consequence the discussion extends to the roles of these surfaces in transpiration and gas exchange.
Ultrastructural observations of the rust fungus Physopella zeae in Zea mays
Authors: Heath Michèle C. , Bonde M. R.
Published: April 2011

Examination of sporulating uredia of the tropical corn rust fungus, Physopella zeae, with the transmission electron microscope revealed that this fungus possessed most of the distinguishing ultrastructural characteristics reported for temperate zone inhabiting members of the Uredinales. Physopella zeae differed from these latter fungi in the repeated production of urediospores from the same site on the sporogenous cell, and in the intracellular location of most of the mycelium. The intracellular mycelium was differentiated into structurally unspecialized hyphae and structurally distinct haustoria arising from differentiated haustorial mother cells which were located in the neighbouring host cell. Both types of intracellular structures were covered with a matrix, and that around the intracellular hyphae was continuous with similar material lining the plant cell wall. The matrix was thicker and more compact around intracellular hyphae than around the bodies of haustoria. The matrix lining the host walls was thinnest in sections of mesophyll cells containing a ratio of haustoria – intracellular hyphae profiles greater than one. These data suggest that the haustorium may actively inhibit matrix formation in invaded plant cells.