bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of barley yellow dwarf virus in aphids by serologically specific electron microscopy
Authors: Paliwal Y. C.
Published: April 2011

A procedure employing serologically specific electron microscopy (SSEM) which consistently detected barley yellow dwarf virus (BYDV) in single aphids was developed. Using an antiserum against the Sitobion avenae (SA)-specific variant of BYDV, the virus was detected in aphids after 1 day of acquisition feeding and up to 9 days after removal from the virus source plant. The method was equally effective with alate or apterous aphids. SSEM scores of single aphids for presence of virus showed good agreement with virus transmission by aphids. In addition to the SA-specific variant, the nonspecific and Schizaphis graminum specific variants of the virus were also detected in their vectors Rhopalosiphum padi and S. graminum, respectively, using the antiserum to SA-specific variant. The SA-specific variant was also detected in aphids considered "nonvectors" (R. padi, R. maidis, and S. graminum) when fed on this variant. Application of the procedure for determining the proportion of viruliferous aphids in a population are discussed.
Influence of preemergence herbicides on pathogenesis by Drechslera sorokiniana on sequentially senescent leaves of Poa pratensis
Authors: Hodges Clinton F.
Published: April 2011

Four preemergence herbicides (benefin, bensulide, DCPA, siduron) were evaluated for their effect on the severity of leaf spot induced by Drechslera sorokiniana (Cochliobolus sativus) on sequentially developing and senescing leaves of a single shoot of Poa pratensis. Preemergence herbicides stimulated, had no effect on, or inhibited leaf spot on shoot leaves of various ages. Stimulation of leaf spot primarily occurred on the two youngest visible leaves of the shoot and was induced by bensulide (all concentrations) and DCPA (10−9, 10−6 M). Benefin and siduron had no effect on leaf spot development on the two youngest leaves and none of the herbicides inhibited leaf spot on the two youngest leaves. The various herbicides were primarily inhibitory of leaf spot development on the two oldest leaves of the shoot. Leaf spot was inhibited on leaf 3 by benefin (10−12, 10−9 M), DCPA (10−12, 10−9 M), and siduron (10−9, 10−6 M); inhibition on leaf 4 was induced by benefin (all concentrations), DCPA (10−12 M), and siduron (10−9, 10−6 M). Only bensulide at 10−12 M stimulated leaf spot on the two oldest leaves and siduron at 10−12 M on the oldest leaf. The predominant stimulation and inhibition of leaf spot by the herbicides on the two youngest and the two oldest leaves of the shoot, respectively, is discussed relative to the usual increase in disease on progressively older leaves.
Effect of an atmosphere of oxygen on growth, respiration, and lignin degradation by white-rot fungi
Authors: Reid Ian D. , Seifert Keith A.
Published: April 2011

Lignin degradation by the white-rot fungi Phanerochaete chrysosporium, Coriolus versicolor, Pycnoporus cinnabarinus, Lentinus edodes, Grifola frondosa, Polyporus brumalis, and Merulius tremellosus was faster in an atmosphere of oxygen than in air. Gloeoporus dichrous, Pleurotus ostreatus, and Bondarzewia berkeleyi degraded lignin at equal rates in oxygen and in air. Increased oxygen partial pressure also stimulated carbohydrate consumption by most of the fungi. In liquid shake culture, the fungi grew as well under an atmosphere of oxygen as air. However, respiration was faster under oxygen, suggesting that the fungi required more energy for growth and maintenance in oxygen. On delignified wood, most of the fungi grew equally rapidly in air and oxygen. Apparently, the growth of these fungi in wood in air is limited by the rate of lignin degradation.
The effect of microhabitat, spatial distribution, and display size on dispersal of Lindera benzoin by avian frugivores
Authors: Moore Linda A. , Willson Mary F.
Published: April 2011

The fruits of Lindera benzoin (L.) Blume are dispersed by several species of birds, mainly thrushes (Turdidae) and mimids (Mimidae). In a study in Trelease Woods, Illinios, removal rates (as percentages) did not keep pace with fruit availability and exhibited a low point in midseason. Relative removal rates in tree-fall gaps initially exceeded those in forest interior, though total fruit abundance there was less. Isolated bushes had slightly higher relative removal rates initially than clumped bushes, again despite a lower availability. Percentage removal rates on bushes with small displays often exceeded those on large displays, although the absolute numbers removed from large displays were greater. Most of these trends held up when factors were considered in combination.
Augmentation of protoplasm in drought- and cold-hardened winter wheat
Authors: Cloutier Y. , Siminovitch D.
Published: April 2011

A 24-h desiccation stress at 40% relative humidity was able to induce the same degree of freezing tolerance as a 4-week cold acclimation at 2 °C does in nine cultivars of winter wheat. These two treatments were also able to elicit similar metabolic changes as indicated by increases of soluble protein and phospholipid contents in shoots. Since the amplitude of these metabolic changes induced by drought and cold stresses were similar, the mechanism or the mechanisms by which these stresses induce freezing tolerance appear to involve the same biochemical modifications.The measured amplitude of these metabolic changes is not always proportional to the net increase of freezing tolerance among those cultivars but depends upon the method used to determine the metabolites. A strong correlation between the amplitude of the increase of soluble proteins and phospholipids and the net increase of freezing tolerance of the cultivars was observed only when the extractions were performed on lyophilized tissues.
Phenology and ecology of color in bird-dispersed fruits, or why some fruits are red when they are "green"
Authors: Willson Mary F. , Thompson John N.
Published: April 2011

Several hypotheses regarding the ecology of color in bird-dispersed fruits in North America are presented and tested. (1) We predicted, but failed to substantiate, an inverse relationship between size and colorfulness of fruiting display. Large fruit crops are more often bicolored than small ones. Red monochrome fruits are relatively common in herbs, but we cannot say if red is more "conspicuous" to birds than blue or black nor if herbs are relatively less conspicuous, when in fruit, than shrubs or trees. (2) Conspicuous displays are most common in plants that fruit at times when avian frugivore abundance is low. This hypothesis is supported strongly by the phenologies of temporally bicolored displays, which are produced commonly in summer before the influx of fall migrants. Data from morphologically bicolored displays are less clear-cut. Temporally bicolored displays may increase fruit dispersal particularly by juvenile birds and (or) decrease conspicuousness to invertebrate predators, as well as increase the level of display attractiveness to whatever dispersal agents are present at the time. (3) Conspicuous displays occur in regions where frugivore abundance is seasonally low. This hypothesis receives some support. A comparison of Illinois (low diversity and numbers of wintering frugivores) with the Carolinas (where both are high) suggested that monochrome displays may be relatively more common, and morphologically bicolored displays less so, in the Carolinas. High frugivore abundance and diversity may relieve competition for dispersors and reduce selection for unusually conspicuous displays.
Early abortion of colonies of leaf rust, Puccinia hordei, in partially resistant barley seedlings
Authors: Niks R. E.
Published: April 2011

Partial resistance (PR) in barley to leaf rust is assumedly a case of durable resistance. PR is characterized by a reduced rate of epidemic development in spite of a susceptible infection type. One of the components of PR, low infectibility, was studied histologically by means of fluorescence microscopy. Quantitative analyses of the phases of the infection process beyond appressorium formation showed that the reduced infectibility of partially resistant barley seedlings rests on a significant "early abortion" of colonies. This type of abortion occurs at about the moment of the formation of the first haustoria, when the young colonies have formed up to five or six haustorial mother cells. Early abortion is only incidentally associated with the collapse of host cells. Not only the variation in infectibility among barley genotypes but also the variation in infectivity among leaf rust isolates is based mainly on differences in the degree of early abortion. The occurrence of a high degree of early abortion in several unrelated barley genotypes indicates that the PR genes are part of a generally occurring system.
Osmotically induced volume changes in protoplasts isolated from Cucurbita ficifolia
Authors: Tyree M. T. , Salleo S. , LoGullo M. A. , Barclay G. F. , Salleo A. , Rosso R.
Published: April 2011

Free membrane-bound protoplasts are formed when turgid stem segments are cross-sectioned into 2-mm-thick slices and placed in a nonplasmolysing solution of electrolyte or mannitol. The protoplasts range in diameter from less than 5 μm to a few more than 80 μm. The larger protoplasts contain a fuller complement of organelles than the small ones, and some large protoplasts form transvacuolar strands and restart cyclosis after 2 to 3 days. The protoplasts change diameter when they are exposed to fusicoccin or 2,4-dinitrophenol; from this we conclude that some of the solute transporters in the bounding membranes are still functioning. The pattern of swelling and shrinking of the protoplasts in response to the change in concentration and composition of the bathing medium leads us to believe that the membranes are very leaky to solutes causing a large coupling between solute and water flow. In addition high capacity net ion transport occurs at rates of up to 2 μosmol∙s−1∙m−2 causing shrinkage of the protoplasts in hypotonic KCl solution even though osmotic considerations force the prediction that the protoplasts will swell. Ion transporters working at the net rate of 0.5 μosmol∙s−1∙m−2 also appear to be responsible for swelling of protoplasts that previously shrank in hypertonic KCl or NaCl.
Taxonomic notes on coprophilous fungi of the Arctic: Churchill, Resolute Bay, and Devon Island
Authors: Booth Tom
Published: April 2011

Various dung substrates including that of arctic fox, arctic hare, arctic wolf, lemming, musk-ox, polar bear, rock ptarmigan, and snow goose were collected from the Churchill region, Resolute Bay region, Scogan Lowland, Sverdrup Lowland, Truelove Lowland, and Truelove Valley. These collections were incubated and surveyed for coprophilous fungi. Of 20 taxa recorded Ascobolus stictoideus, Cheilymenia coprinaria, Coprobia granulata, Lilliputia rufula, Sporormiella bipartis, Sporormiella dubia, Sporormiella minima, Sporormiella septenaria, and a Zopfiella sp. are first reports for Arctic sites. Taxonomic problems are discussed in some detail for Sporormiella intermedia and Thelebolus polysporous.
Cladistic analysis of Triticeae by means of Farris's "distance Wagner procedure"
Authors: Baum Bernard R.
Published: April 2011

A dissimilarity matrix of genera of Triticeae, computed from the amalgamation of morphological data and genetic relationships in terms of successful crosses between the genera, has been subjected to Farris's distance Wagner procedure. One of the almost identical two Wagner networks obtained was superimposed on an ordination plot of the genera in two-dimensional space. This enabled representation of the multidimensionality of the phylogenetic relationships among the genera of this tribe. The findings and interpretation are discussed and compared with results on intergeneric relationships obtained by various cytogeneticists.
Puccinia phaeospora sp. nov., a perfect state of Aecidium nanocnides
Authors: Ono Yoshitaka , Kakishima Makoto
Published: April 2011

Aecidium nanocnides Dietel was experimentally proven to be an aecial stage of Puccinia sp. on Carex aphanolepis Fr. &Sav. in Japan. This rust differed in morphology and life cycle from the other caricicolous Puccinia, and was named Puccinia phaeospora Kakishima & Ono, sp. nov.
Structure and biology of a new hyphomycete parasitic on rotifers
Authors: Barron G. L. , Szijarto E.
Published: April 2011

Phialophora endoparasitica is described as a new hyphomycete attacking bdelloid rotifers. Infection is initiated by a conidium with a lobed appendage which lodges in the mastax. Conidia germinate to produce branching chains of turbinate assimilative cells which eventually fill the host. Reproductive hyphae break out at a number of points, produce phialidic conidiogenous cells, and release conidia under water.
New and interesting Chaetomium species from East Africa
Authors: Carter A. , Khan R. S.
Published: April 2011

Three new coprophilous Chaetomium species are described and illustrated: C. subcircinatum from Tanzania, C. retardatum from Kenya and Zaire (Congo), and C. multispirale from Kenya, Canada, and Mexico. Many additional records are provided for 13 previously described species and species groups, several of which are redescribed from pure cultures. A comparison of two closely related species, C. globosum and C. coarctatum, is presented.
The responses of photosynthesis and translocation rates to changes in the ζ ratio of light
Authors: Hoddinott John , Hall Linda M.
Published: April 2011

The influence of wide spectrum illumination conditions, with red and far-red light mixed to simulate sun and shade conditions, upon rates of photosynthesis and translocation was observed. A steady-state 14CO2 labeling apparatus was used to measure the two processes simultaneously during a light quality change. Sun conditions supported lower rates of photosynthesis and translocation to illuminated sink leaves than shade conditions, but the rate of translocation was lower than expected on the basis of the decline in photosynthesis. Translocation rates to darkened sinks remained constant as the photosynthetic rates were altered by changing light quality. Sink leaflet growth rates were lower in sun than shade light. We conclude that this decline in growth rate, which is also a decline in sink strength, results in light quality exerting a smaller effect on translocation than on photosynthesis.
Protein bodies in umbelliferous seeds. II. Elemental composition
Authors: Spitzer Ernest , Lott John N. A.
Published: April 2011

The elemental composition of the protein bodies from several members of the Umbelliferae including carrot (Daucus carota L. cv. Imperator 408), wild carrot (Daucus carota L.), caraway (Carum carvi L.), anise (Pimpinella anisum L.), dill (Anethum graveolens L.), celery (Apium graveolens L. cv. Tall Utah), fennel (Foeniculum vulgare Mill.), parsnip (Pastinaca sativa L. cv. Hollow Crown), parsley (Petroselinum sativum L. cv. Moss Curled), and chervil (Anthriscus cerefolium L. cv. Curled) was determined using energy dispersive X-ray analysis. Globoid crystals in the endosperm usually contained P, K, and Mg or infrequently P, K, Mg, and Ca. In the embryos of carrot and caraway, P was always present with a combination of K, Mg, or Ca. Calcium was the only element detectable in the calcium-rich crystals. The proteinaceous matrix always contained S and K regardless of the inclusion present in the protein body.Quantitative determinations of P, Mg, K, and Ca are presented for all members studied except wild carrot, chervil, celery, and fennel. In all species analysed in this manner K or Ca were present in the highest amounts followed by P and Mg. Calcium-localization studies showed that most of the Ca is located in the endosperm and pericarp portions of the mericarp.
Floral development in Phoenix dactylifera
Authors: Mason Darleen A. De , Stolte Kenneth W. , Tisserat Brent
Published: April 2011

Inflorescence primordia in the date palm (Phoenix dactylifera L.) differentiate within axillary buds in November in the Coachella Valley, California. The rachillae are initiated as small mounds without subtending bracts on the flattened apex of the rachis and are enclosed by the prophyll. A single bract subtends each flower primordium. Flower primordia are initiated in an acropetal sequence along the rachillae. Although mature flowers are functionally unisexual, early development is similar in staminate and pistillate flowers. Six perianth parts are initiated within two alternating whorls: the sepals and the petals. Six stamens are initiated in two alternating whorls of three stamens each, the first opposite the sepals and the second opposite the petals. Lastly, three separate carpels are initiated. Pistillate and staminate flowers are identical and apparently bisexual at this stage. The two flower types diverge developmentally when the stamens become bilobed and elongate in the staminate but not the pistillate flowers. The pistillodes in the staminate flowers form rudimentary stigmatic surfaces at the tip of the carpels and meristematic lumps corresponding to the position of the ovule in normal carpels. The staminodes mature in the pistillate flowers as small triangular projections. Meiosis occurred in staminate and pistillate flowers (in March 1979) when the staminate flowers were about 5 mm long and the pistillate flowers were about 3 mm long.
Some aspects of the vegetation ecology of the Little Qualicum River estuary, British Columbia
Authors: Dawe Neil K. , White Eric R.
Published: April 2011

Nine vascular plant communities were determined and mapped from data gathered on the Little Qualicum River estuary, Vancouver Island, B.C., during the period May to September 1978. Those communities comprised 51 species of vascular plants; however, only 10 species occurred with constancies of 20% or greater. Carex lyngbyei, Potentilla pacifica, Juncus balticus, and Agrostis sp. dominated vegetation. Major factors affecting the distribution of the vegetation within the estuary appeared to be site elevation, soil type and texture, and inundating water salinity. Aerial production was dominated by that of the Carex – channel edge community which had a peak aboveground biomass of 1693 g dry weight∙m−2.
In vitro flowering on leaf explants of Streptocarpus nobilis. The influence of culture medium components on vegetative and reproductive development
Authors: Simmonds John
Published: April 2011

Streptocarpus nobilis (C.B. Clarke) became photoperiodically more responsive to short days with increasing age. Leaf explants from photoperiodically induced plants were all organogenically competent when cultured on Murashige and Skoog medium in 8-h photoperiods. Both vegetative and flower buds were developed; the maximum level of in vitro flowering occurred in response to 6-benzylaminopurine (BAP), but only 50% of the explants produced flowers. 3-Indoleacetic acid (IAA) (1 × 10−7 to 1 × 10−6 M) inhibited in vitro flowering. A nutrient medium was devised which allowed the expression of flowering on 100% of explants. The expression of vegetative or reproductive development was strongly influenced by the concentrations of media nutrients. On high-KNO3 (20 mM) – high-sucrose (100 mM) medium vegetative development was favoured and flower buds were produced on only 28% of explants. On low-KNO3 (2 mM) – low-sucrose (15 mM) medium only flower buds were developed on all explants. On low-KNO3 (5 mM) medium organogenesis was also affected quantitatively by the sucrose concentration; organogenesis was reduced from 90% explant response on 25-mM sucrose medium to 52% explant response on 100-mM sucrose medium. The most rapid flowering response to low-KNO3 (2 mM) – low-sucrose (15 mM) medium was obtained on explants from leaves of axillary branches. Flower buds were formed on the main vein at the proximal region of the explant. This high response at a predictable location provides a useful system for investigating flowering.
Starch-enhanced synthesis and release of amylolytic enzymes from normal and crown gall tumor tobacco tissue culture cells
Authors: Voliva Charles , Moessen Gustave W. , Matthysse Ann G.
Published: April 2011

The response of tobacco crown gall tumor cells growing in tissue culture to a substitution of starch for sucrose as the carbon source in the medium was compared with the response of normal tobacco tissue culture cells. In both cases amylolytic activity was secreted into the medium. The increase in extracellular amylolytic activity was preceded by an increase in intracellular activity. The increase in intracellular amylolytic enzymes was sensitive to cycloheximide and to actinomycin D indicating that enzyme induction at the level of mRNA synthesis was required. No significant difference between the responses of normal and tumor cells was observed. Thus crown gall tumor cells were as capable as normal cells of sensing and responding to an alteration in the carbon source in the external medium.
The species of Thecaphora on Compositae in North America
Authors: Durán Rubén
Published: April 2011

Five new species of Thecaphora collected in Mexico are described, some of which are parasitic on genera of Compositae not previously reported as hosts. Species of Thecaphora on Compositae for the North American continent now total 11. New species include Thecaphora denticulata, T. heliopsidis, T. hennenea, T. melampodii, and T. neo-mexicana. New host genera for North America include Bidens, Heliopsis, and Melampodium. Morphological characteristics of Thecaphora species and taxonomic criteria to delimit them are discussed. Keys to the species, interpretations of spore ball morphology and spore sculpturing, and scanning electron and bright-field micrographs are presented.
Ontogeny of dichotomizing apices in mycorrhizal short roots of Pinus strobus
Authors: Piche Yves , Fortin J. André , Peterson R. L. , Posluszny U.
Published: April 2011

Growth pouches were used to establish ectomycorrhizae of Pinus strobus using Pisolithus tinctorius as inoculum. An epi-illumination technique was used to follow changes in external morphology of short roots as they became colonized by hyphae and dichotomized. Apices became broader and flatter before an obvious dichotomy was apparent. Secondary dichotomies often formed after the primary dichotomy of the original short roots. Sectioned material showed that a central group of cells in the meristem stopped dividing and became vacuolated as dichotomy was initiated. Two lateral growth centres were established which led to the formation of two apical meristems.
Geographic variation in a widespread perennial weed, Rumex crispus. The relative amounts of genetic and environmentally induced variation among populations
Authors: Hume L. , Cavers P. B.
Published: April 2011

Populations of Rumex crispus were sampled from eastern North America and Europe. The relative amounts of genetic variation and plasticity were examined, using 58 plant characters. About 61% of the total variation occurring in the experimental plants was accounted for by plasticity. The remaining 26% and 13% occurred within populations and among widespread populations, respectively. At the local level, there was little difference between variation occurring within genotypes and that within families (between maternal siblings). This suggests that the species is predominantly inbreeding. The majority of genetic variation occurs within populations at both the local and species' range levels.It was concluded that the species has large amounts of both flexibility and genetic heterogeneity. This adaptive strategy enables the species to survive under a very wide range of environmental situations and largely accounts for its becoming one of the most widely distributed plants in the world.
Electron-probe microanalysis of silicon in the adventitious roots and terminal internode of the culm of Zea mays
Authors: Bennett Daphne M. , Sangster A. G.
Published: April 2011

The adventitious roots and terminal internode of the culm of mature, field-grown specimens of five cultivars of Zea mays L. were investigated with relation to silicon, using electron-probe microanalysis. No silicon was detected above the background level within the endodermis or any other tissues within the adventitious roots. In contrast, however, in the terminal internode silicon was present in the outermost layers of cells, the highest levels being detected in the outer epidermal wall. It was also present in the internal epidermal cell wall, as well as in the walls of underlying tissues of the outer region of the culm, in the sclerenchyma, and at a low level in the parenchyma forming the ground tissue. Thus, the culms displayed a decreasing gradient of silicon content, probably in the form of amorphous silica gel, in cell walls, proceeding from the outermost layer, the epidermis, to the centrally located ground parenchyma, a result generally consistent for all five cultivars. The results are discussed in relation to the anatomy of these tissues and their silicification.
Calendrier des sporogénèses et gamétogénèses femelles chez le diploïde et le tétraploïde induit de Brachiaria ruziziensis (Graminée)
Authors: Gobbe J. , Longly Béatrice , Louant B.-P.
Published: April 2011

The processes leading to the formation of the gametes are described in two sexual forms of Brachiaria ruziziensis Germain et Evrard: the natural diploid and an induced autotetraploid. This description comes within the framework of an interspecific hybridization program in the genus Brachiaria aiming at the transfer of the genes responsible for apomixis from polyploid apomictic to diploid sexual species. A "reproductive calendar" is established where microsporogenesis and microgametogenesis are used as reference scales for the concomitant events of megasporogenesis and megagametogenesis of the two forms. This calendar will be compared with similar ones which have to be established for B. decumbens Stapf. and B. brizantha (Hochst) Stapf., natural tetraploid apomicts. Differences were noticed between the original diploid and the induced tetraploid form.
The disposition of benzo(a)pyrene in the periphyton communities of two South Carolina streams: uptake and biotransformation
Authors: Bruno Mary G. , Fannin Timothy E. , Leversee Gordon J.
Published: April 2011

The effect of periphyton community composition and colonization time on the uptake and biotransformation of benzo(a)pyrene (BaP) was determined in laboratory studies. Naturally colonized glass microscope slides were collected after 3 and 6 weeks from Castor Creek, which has a predominantly desmid flora, and after 3 and 5 weeks from diatom-dominated Upper Three Runs Creek. When expressed on a slide surface-area basis, the Castor Creek periphyton showed significantly greater BaP uptake rates at both colonization periods. Within streams, uptake rates increased significantly with colonization time. Autoradiographic analysis suggests that BaP was accumulated by surface sorption, especially to gelatinous sheath material. Active biotransformation as measured by the percentage extractable non-BaP 14C was not detected in either community.
Inheritance of an ascospore abortion factor in Venturia inaequalis
Authors: Yoder K. S. , Klos E. J. , Nowacka H. , Bielenin A.
Published: April 2011

The inheritance of an ascospore abortion factor arising from a dodine-tolerant isolate (SR4) of Venturia inaequalis was investigated. The presence of F1 progeny as tolerant as SR4 but permitting normal development in test crosses indicated that the factors causing ascospore abortion were not the same as the genes conditioning higher levels of tolerance to dodine. In crosses of SR4 with isolates not inducing ascospore abortion, only 2% of the asci contained eight spores. Groupings of asci having one or two spores, three or four spores, and five or six spores included 19%, 48%, and 31% of the total, respectively. The effects of ascospore abortion in progeny of isolate SR4 are similar to some previously reported cases in other fungi. The recurrence of similar frequencies of abortion in crosses of SR4 and in test crosses of F1 progeny of SR4, the tendency for ascospores to be aborted as pairs rather than singly, and an additive abortive effect in crosses combining the abortion-inducing SR4 progeny and the color mutants known to cause ascospore abortion suggest that the ascospore abortion occurring in progeny of isolate SR4 is under genetic control. The variable frequency of asci having uneven numbers of spores is not readily explained genetically and suggests that cultural conditions may also influence ascospore abortion.
Anatomical modification by 2,4-DB of vascular cambium and secondary xylem in soybean internodes
Authors: Pizzolato Thompson Demetrio
Published: April 2011

Anatomical changes in the vascular cambium and secondary xylem of the first internode of soybeans were observed 15 days after an aqueous spray of 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB) was applied at 0.56 kg acid equivalent per hectare. The cambium became a meristem of initials, which were intermediate in morphology between normal ray and fusiform initials, and the system of ray initials was lost. The xylem lost its rays and became a tissue in which narrow vessel members abnormally outnumbered the axial parenchyma cells, libriform fibers, and gelatinous fibers which were common in normal wood. The herbicide inhibited the normal expansion of vessel-member primordia.
Studies of nitrate influx into barley roots by the use of 36ClO3− as a tracer for nitrate. 1. Interactions with chloride and other ions
Authors: Deane-Drummond Celia E. , Glass Anthony D. M.
Published: April 2011

The effect of various anions on the short-term influx on NO3− into barley roots was examined by the use of 36ClO3− as a tracer for nitrate. NO3− (36ClO3−) influx was found to be extremely sensitive to inhibition by external Cl− (Ki = 0.035 mM). By contrast 36Cl− influx was not significantly affected by external NO3−. Other anions, SO42− and H2PO4−, had no effect on NO3− (36ClO3−) influx, while HPO42−exerted a slight inhibitory effect. In the range from pH 4 to pH 8 no significant effect of OH− concentration on NO3− (36CIO3−) influx was detected. When barley roots were pretreated for periods up to 4 h with 10 mM NO3−, there was a significant reduction in NO3− (36ClO3−) and 36Cl− influx. KCl at the same concentration (10 mM) caused similar reductions of NO3− (36ClO3−) and Cl− influx. When plants were pretreated with lower NO3− or Cl− concentrations (0.05–5.0 mM) for 2 days, Cl− influx was found to be more sensitive than NO3− (36ClO3−) influx to nitrate or chloride pretreatment.
Bilans nutritifs glucidique et azoté de tissus de tubercules de topinambour cultivés in vitro après irradiation gamma
Authors: Schaeverbeke-Sacré Janine , Matheron Béatrice
Published: April 2011

Carbohydrate and nitrogen budgets were studied in Jerusalem artichoke tuber explants cultured in vitro after gamma irradiation (0 to 106 rads (1 rad = 10−2 J/kg)). A certain level of reducing sugars is reached and retained in all the explants and, in all cases, an increase of protein nitrogen is observed. The highly irradiated tissues have a very disturbed metabolism that involves in particular, amino acid leaching into the culture medium.
Structure and function of a cyanophytan mat community in an acidified lake
Authors: Lazarek Stanislaw
Published: April 2011

The structural and functional properties of a cyanophytan mat in an extremely oligotrophic acidified lake were studied. The mat forms a physiological unit well adapted to acid conditions in the lake. Two to three millimetres of the uppermost stratum consists of photosynthetically active filaments of Lyngbya with an intrusion of other benthic algae. Relatively high rates of algal primary productivity and low rates of N2 fixation were recorded in the mat.
Initial vesicular–arbuscular mycorrhizal development of slender wheatgrass on two amended mine spoils
Authors: Zak J. C. , Parkinson D.
Published: April 2011

The initial vesicular–arbuscular (VA) mycorrhizal development of slender wheatgrass on extracted oil-sands and subalpine coal-mine spoils, amended with either fertilizer, peat, or liquid sewage sludge, was examined. Plants were sampled at 2, 6, and 10 weeks after plant emergence and the level of infection was expressed as length of mycorrhizal root per plant and length of root which contained arbuscules, vesicles, or only hyphae. Mycorrhizal infection of slender wheatgrass on the oil sands was limited to plants on the peat-amended spoil. Infection of plants on the peat-amended oil-sands spoil was detected by 2 weeks. Plants on the subalpine spoil were infected at 2 weeks only on the peat-amended spoil. While slender wheatgrass on the control and fertilizer-amended spoil developed mycorrhizae by 6 weeks, infection was not observed in plants on the sewage-amended spoil until 10 weeks. At 10 weeks, there were no significant differences in lengths of mycorrhizal root per plant among the amendments. Increased P levels in the fertilizer- and sewage-amended subalpine spoil did not suppress VA mycorrhizal development.
Nitrogen immobilization in decaying hardwood leaf litter as a function of initial nitrogen and lignin content
Authors: Aber John D. , Melillo Jerry M.
Published: April 2011

Equations presented in an earlier paper, expressing organic matter and nitrogen dynamics in decomposing hardwood leaf litter, are extended to predict nitrogen immobilization patterns in litters of varying initial lignin and nitrogen content. A continuum of immobilization rates coincides with the successional status of the six northern hardwood species examined, with early successional species exhibiting the fastest rates. By using data from the literature, similar trends were found for southeastern hardwoods. Patterns for important species from Douglas-fir forests of the Pacific Northwest are quite different and may reflect differences in nitrogen availability following disturbance.
Water-soluble products from the degradation of aspen lignin by Phanerochaete chrysosporium
Authors: Reid Ian D. , Abrams Garth D. , Pepper James M.
Published: April 2011

When Phanerochaete chrysosporium degrades [14C] lignin-labelled aspen wood in static liquid culture, it releases almost as much 14C in water-soluble form as in 14CO2. Water-soluble ultraviolet-absorbing materials also accumulate in cultures that are degrading lignin. The water-soluble radioactive materials appear to be intermediates in lignin degradation, because they can be further metabolized to CO2 and because the soluble materials labelled during [14C] lignin degradation are distinct from the materials labelled during [14C] glucose metabolism. These lignin degradation products can be fractionated by gel chromatography and are mostly acidic.
Variegation in Selaginella martensii f. albovariegata. II. Plastid structure in mature leaves
Authors: Tanno James A. , Webster Terry R.
Published: April 2011

Mature green, variegated, and white leaves of Selaginella martensii f. albovariegata were examined by light and electron microscopy. Paraffin sections show the anatomy of all three leaf types to be comparable with that reported for wild type S. martensii. With the light microscope, chloroplasts in green cells appear identical with those of the wild type, while plastids in white cells are smaller and less regular in shape. Chloroplast ultrastructure in green cells is comparable with that described for S. martensii and other members of the genus and quite similar to that typical of seed plants. Plastids of white cells display many structural defects. Large portions of the plastid volume are occupied by vacuoles. In variegated leaves these plastids possess sparse internal membrane systems consisting primarily of irregular vesicles distributed throughout the stroma. In white leaves single lamellae and sets of aligned lamellae are associated with many of the plastid vacuoles. The plastid defects suggest a high susceptibility to photooxidative bleaching.
A key to identify epidermal fragments of Saskatchewan rangeland plants
Authors: Riegert P. W. , Singh Noreen
Published: April 2011

A descriptive key and plates of drawings showing epidermal structures are presented. Their use will permit the identification of 53 species of forbs and grasses that may comprise the diet of herbivores, such as grasshoppers, when ingested as leaf fragments.
A phylogenetic analysis of the tribe Triticeae (Poaceae) based on morphological characters of the genera
Authors: Baum Bernard R.
Published: April 2011

A phylogenetic analysis of Triticeae was performed by means of numerical methods. Five methods, each based on extreme assumptions of parameters so interpreted under Felsenstein's (1979) evolutionary model, were used: Camin–Sokal parsimony, Wagner parsimony, Dollo parsimony, polymorphism parsimony, and character-compatibility analysis. Although a considerable amount of parallelism was, for some time, suspected to have occurred in Triticeae (by Stebbins for instance) so that for this reason perhaps the assumptions of polymorphism parsimony might be most suitable for phylogenetic analysis, the five methods were used because the evolutionary assumptions for each investigated character are, and probably will long remain, unknown.Data input consisted of sets of hypothesized transformation series, each set subjected to analyses using the five methods. Results of an analysis provided the basis for altering the set of hypothesized transformation series for subsequent analysis. Analyses were carried out repeatedly until stabilization; that is until, in the author's judgment, the most parsimonious solution was arrived at and further trials were of diminishing return. The most parsimonious tree obtained served as a base for subsequent elaboration of the final tree, taking into consideration genetic information primarily, and for the erection of the proposed phylogenetic classification of Triticeae. A key is provided for identification of the groupings in the tribe. The proposed classification is discussed in the light of previous classifications, even though none of them were phylogenetic in the sense of Hennig.
A clearing technique for embryos of lipid-storing seeds
Authors: Shih C. Y. , Peterson Carol A. , Dumbroff E. B.
Published: April 2011

A method was devised which effectively cleared mature embryos of maple (Acer saccharum Marsh.), rape (Brassica rapa L.), watermelon (Citrullus vulgaris Schrad.), and sunflower (Helianthus annuus L.). The embryos were fixed and decolorized with acetic acid – ethanol, their lipids extracted with petroleum ether, their proteins extracted with sodium hydroxide followed by chloral hydrate, and their residual material extracted with sulfuric acid. After clearing, both xylem and phloem were readily observed in embryos that were in the early stages of germination.
Cytochemical investigations on multiple bud formation in tissue cultures of Pinus coulteri
Authors: Patel Kamlesh R. , Berlyn Graeme P.
Published: April 2011

Cytochemical events associated with formation of multiple shoots on cultured embryonic explants of Pinus coulteri were studied. The first step in the developmental pattern leading to multiple adventitious bud formation was the establishment of organogenetic domains defined by increased RNA, DNA, and basic nuclear proteins. The succeeding step was the accumulation of reserves such as lipids, proteins, and especially starch. This was followed by utilization of reserves characterized by high lipase and amylase activity in the domains. However, some of the subjacent callus cells also exhibited high lipase and amylase activity, indicating the mobilization of reserves for organogenesis. As meristemoids formed, there was an increase in enzyme activities concerned with energy production and utilization. Differentiating shoot primordia and developing needles showed high activities of acid phosphatase, glucose-6-phosphatase, and succinate dehydrogenase. Intense localization of reducing substances (chiefly ascorbic acid) and increased ATPase activity suggested that there was a considerable utilization of energy associated with elevated metabolism in the meristemoids and developing buds. Peroxidase was strongly localized in regions of growth and differentiation, especially developing vascular strands. It is concluded that these cytochemical events reflect distinctive changes in cellular metabolism associated with the intitiation and development of multiple shoots on the cultured explants of P. coulteri.
Pleomorphism in Ceratocystis ulmi: chlamydospore formation
Authors: McNeel Donna J. , Kulkarni Rajiv K. , Nickerson Kenneth W.
Published: April 2011

Conditions are described for the synchronous production of chlamydospores from both the yeast and mycelial phases of Ceratocystis ulmi, the causative agent of Dutch elm disease. In a defined liquid medium the pH value is critical. Chlamydospores are formed from pH 2 to pH 3 but not above pH 3. The chlamydospores are fully viable and reproduce via germination following a 2-month aging period. The chlamydospores formed from yeasts and mycelia differ, however, with respect to both cell wall chemistry and size (Y = 5.1–9.2 μm; M = 10.9–12.7 μm). A morphological-phase diagram is presented depicting the complete developmental potential of C. ulmi.
Pleomorphism in Ceratocystis ulmi: refractile lipid bodies
Authors: Kulkarni Rajiv K. , Nickerson Kenneth W.
Published: April 2011

Evidence is presented that the refractile bodies present in yeasts and blastospores of proline-grown Ceratocystis ulmi, causative agent of Dutch elm disease, are lipid storage bodies rather than viable microendospores. Additionally, it is hypothesized that the lipid bodies of C. ulmi grown in susceptible elm trees are enriched in unsaturated fatty acids and that the aggressive vs. nonaggressive distinction in C. ulmi can be interpreted in terms of the percent unsaturated fatty acids in their lipids.
Characterization of a lysosomal proteinase purified from haploid cells of Physarum flavicomum undergoing encystment
Authors: Henney Jr. Henry R. , White Hiltrud U.
Published: April 2011

Haploid cells of Physarum flavicomum differentiating to dormant microcysts exhibited prominent Golgi bodies, lysosomes, and autophagic vacuoles digesting intracellular materials. Total intracellular acid proteinase activities, as well as enzyme specific activity, increased during the encystment process. Lysosomes, isolated by fractionation of cell extracts on sucrose density gradients, were identified by their ultrastructural characteristics as well as their content of the following enzymes of high specific activity: acid proteinase, acid β-galactosidase, acid phosphatase, and β-glucuronidase. The lysosomal acid proteinase was chromatographically purified, and its molecular weight was estimated to be 32 000. The proteinase was most stable in the pH range of 2–3 which similarly corresponds to its pH optimum using hemoglobin and Azocasein, respectively, as substrates. Its isoelectric point was about 2. The enzyme exhibited little activity and was unstable at pH 7 and above. The rate of activity of the proteinase was maximal at 55 °C, and good stability of the enzyme was noted up to 45 °C. The proteinase required a thiol reagent for stability. Pepstatin, which specifically affects acid proteinases, inhibited the enzyme. Also, compounds reactive with enzyme thiol groups were highly effective inhibitors of the proteinase. The lysosomal enzyme is an acid (carboxyl) proteinase with essential thiol groups.
Responses of endomycorrhizal plants grown in a calcined montmorillonite clay to different levels of soluble phosphorus. I. Effect on growth and mycorrhizal development
Authors: Plenchette Christian , Furlan Valentin , Fortin J. Andre
Published: April 2011

Greenhouse experiments were conducted to compare the growth of mycorrhizal and nonmycorrhizal plants in a calcined montmorillonite clay (Turface) supplied with nutrient solutions of different P concentrations. Apple (Malus pumila Mill., var. Beautiful Arcade), leek (Allium porrum L., var. American Flag), and marigold (Tagetes patulus L., var. Golden Boy) plants were inoculated with 1 g of fresh leek roots colonized singly with the following endomycorrhizal fungi: Glomus epigaeum Daniels & Trappe, Glomus monosporum Gerd. & Trappe, Glomus sp. 3, and Glomus sp. 5. Each experimental plant was inoculated with one of two fungal species at five levels of P. In addition, marigold was inoculated by one fungal species at eight levels of P. The results show that in all cases the inoculated plants grew better than the noninoculated ones, even at high P levels. However, in the first three experiments, the two fungal species used had similar effects on the plant growth. The root endomycorrhizal colonization (REC) indexes decreased when P levels increased, but very much less for leek than for apple and marigold plants. In the second experiment with marigold, starting with level V, the intramatrical structures were altered and the usual vesicular–arbuscular (VA) endomycorrhizal structures almost disappeared; however, the growth stimulation of marigold plants inoculated with G. epigaeum remained. The different fungi can apparently reach the same level of colonization provided the appropriate levels of soluble P are used. The authors suggest a thorough evaluation of the infectivity and the efficiency of a given endomycorrhizal fungus on a given host plant; experiments should be conducted with different levels of P.
Responses of endomycorrhizal plants grown in a calcined montmorillonite clay to different levels of soluble phosphorus. II. Effect on nutrient uptake
Authors: Plenchette Christian , Furlan Valentin , Fortin J. Andre
Published: April 2011

Greenhouse experiments were performed to compare the nutrient uptake of mycorrhizal and nonmycorrhizal plants grown in a calcined montmorillonite clay (Turface) supplied with nutrient solution containing different amounts of P. The host plants used were apple (Malus pumila Mill., var. Beautiful Arcade), leek (Allium porrum L., var. American Flag), and marigold (Tagetes patulus L., var. Golden Boy) and the inocula were Glomus epigaeum Daniels & Trappe, Glomus monosporum Gerd. & Trappe, Glomus sp. 3, and Glomus sp. 5. In general, mycorrhizal plants had higher tissue P concentrations than nonmycorrhizal plants only at the lowest level of P fertilization. Concentrations of nutrients other than P were also enhanced in mycorrhizal plants at P levels I and II depending on the host plant. It appears that both inocula used with each host plant had identical effects on nutrient uptake. It is concluded that neither total P uptake nor N, P, K, Ca, Mg, Cu, and Zn concentrations can explain the growth stimulation of mycorrhizal plants when P fertilization was higher than level II. This suggests that the stimulation in inoculated plants might be attributed to the interaction of one or more fungal metabolites with the growth processes of the host plant.