bluuebunny/crossref_metadata_2025 huggingface dataset:
Within- and between-population variation in ramet behaviour in the gynodioecious clonal herb, Glechoma hederacea (Labiatae)
Authors: Slade Andrew J. , Hutchings Michael J.
Published: September 2007

Clones of the gynodioecious herb Glechoma hederacea L. produce ramets which flower and bear seed, ramets which flower but fail to bear seed, and sterile ramets. Performance and survivorship of these subsets of ramets were compared for hermaphrodite and male sterile clones in contrasting grassland and woodland habitats for 2 consecutive years. For all clones, ramet densities on given dates were comparable between years. Winter survival of ramets exceeded 95% and mortality during the growing season was exponential. No genet recruitment was recorded throughout the study. For all clones, flowering ramets were larger than nonflowering ramets. Both flowering and nonflowering ramets of hermaphrodite clones, from grassland and woodland, were significantly larger than corresponding types of ramets from male sterile clones. A higher proportion of ramets of hermaphrodite clones flowered and set seed than ramets of male sterile clones. Flowering ramets of hermaphrodite clones produced more flowers than flowering ramets of male sterile clones. For all clones, half-lives of subsets of ramets declined in the order: seed-bearing > flowering but not seed-bearing > nonflowering. Within the grassland habitat, ramet subsets from hermaphrodite clones had longer half-lives than corresponding subsets from the male sterile clones. In the absence of greater flowering and seed set by male sterile clones, self-incompatibility of hermaphrodite flowers, which has been reported previously for G. hederacea, is crucial for the maintenance of clones of both sexes in populations.
Control of morphogenetic pathways in thin cell layers of tobacco by pH
Authors: Cousson A. , Toubart P. , Van K. Tran Thanh
Published: September 2007

Thin cell layer explants of tobacco were floated in vitro on the surface of liquid culture media. The initial exogenous concentrations of indolyl-3-butyric acid, and kinetin, the initial medium pH, and the explant density were varied. Various patterns of de novo and direct differentiation without any intermediate callus (flower, vegetative bud, root) as well as the absence of morphogenesis and callus formation without any subsequent organogenesis were separately controlled on 100% of the explants. On the same exogenous combination of glucose, indolyl-3-butyric acid, and kinetin, changes in initial medium pH changed the pattern of morphogenesis. For a given initial exogenous indolyl-3-butyric acid concentration, vegetative buds were obtained at either pH 6.1 or 7.8, whereas a mixture of flowers and vegetative buds was obtained at pH 6.8. Furthermore, changes in explant density changed the morphogenetic response. It is suggested that the effects of the initial medium pH and explant density on morphogenesis may be related partially to modifications of the physicochemical properties of the cell wall and (or) plasmalemma.
The distribution of cucumber mosaic virus in resistant and susceptible plants of pepper
Authors: Dufour O. , Palloix A. , Selassie K. Gebre , Pochard E. , Marchoux G.
Published: September 2007

Immunofluorescence microscopy, azur A staining of viral inclusion bodies, and ELISA tests revealed differences between resistant and susceptible decapitated plants of pepper for virus distribution through the plant but not for virus multiplication and spread in the artificially inoculated leaves. Within 7 to 10 days after inoculation, viral antigens were detected with ELISA tests in all organs of the susceptible plants; only in inoculated leaves of highly resistant plants; and in inoculated leaves, primary stems, and primary roots of partially resistant plants. Immunofluorescence microscopy revealed that infection in petioles, stems, and roots of resistant varieties was restricted to one or two phloem bundles and did not spread to neighbouring tissues or to other plant organs. However, in some partially resistant plants the virus spread lately to other tissues and organs, resulting in a delayed systemic infection and mosaic symptoms on one or two axillary shoots.
Interactions of the nonhost French bean plant (Phaseolus vulgaris) with parasitic and saprophytic fungi. III. Cytologically detectable responses
Authors: Fernandez Myriam R. , Heath Michèle C.
Published: September 2007

Cytologically detectable responses of the nonhost French bean (Phaseolus vulgaris L. cv. Pinto) to saprophytic and parasitic fungi were examined when fungal spores were introduced into heated or unheated leaves via wounds or by injection. Although similar types of responses were observed in interactions with all the fungi, some of these responses were characteristic of each group (saprophytes vs. parasites) in the frequency and (or) extent with which they were elicited. Differences in responses between and within each of these groups of fungi were more related to their degree of adaptation for parasitism than to their taxonomic relationships. Certain responses that were typically elicited by the saprophytes occurred to a lesser extent in tissue responding to the parasites, suggesting that the ability to not trigger, or suppress, these responses may be a general feature of parasitic fungi. None of the fungi elicited significant levels of plant cell necrosis, and for two of the saprophytes, dead spores elicited a lower frequency of responses than live ones. The data indicate that many of the responses of a nonhost plant to living fungi may be the result of reactions to fungal activity rather than to constitutive recognition molecules such as components of the fungal cell wall.
Colonization of crop and pasture species with vesicular–arbuscular mycorrhizal fungi and a negative correlation with root infection by Bipolaris sorokiniana
Authors: Thompson J. P. , Wildermuth G. B.
Published: September 2007

The roots of 37 crop and pasture species were assessed for vesicular–arbuscular mycorrhizae in a vertisol containing spores of vesicular–arbuscular mycorrhizal fungi mainly Glomus mosseae, and of the pathogenic fungus, Bipolaris sorokiniana. The level of mycorrhizal colonization of different hosts is an important aspect of managing crop sequences to reduce "long fallow disorder." All species except rapeseed in the Cruciferae and lupin in the Leguminosae were hosts, although perennial rye grass in the Gramineae had only very slight colonization. The percent root length colonized as assessed by the grid-intersect method ranged up to 60.5% for wheat in the winter series and up to 98.4% for mungbean in the summer series. Greatest weights of mycorrhizal roots were produced by phalaris grass, chickpea, safflower, cocksfoot, lucerne, and barley in the winter series and by lucerne, maize, canary seed, Sudan grass, grain sorghum, and buffel grass in the summer series. Although Gramineae as a group tends to have fine roots with a low percentage of mycorrhizal colonization, the total weight of mycorrhizal roots can be large, and they should be at least equal to legumes in effectiveness for breaking long fallow disorder. Percentages of mycorrhizal colonization determined by the grid-intersect and three slide methods were generally well correlated with one another, but all were less strongly correlated with weight of mycorrhizal roots for winter crops and were entirely uncorrelated with weight of mycorrhizal roots for summer crops. Significant inverse-regression relationships were obtained between infection of root segments (but not of stem bases) by B. sorokiniana and root colonization with vesicular–arbuscular mycorrhizae, indicating that vesicular–arbuscular mycorrhizal fungi antagonise root infection by B. sorokiniana.
Location of radial oxygen loss and zones of potential iron uptake in a grass and two nongrass emergent species
Authors: Conlin Timothy S. S. , Crowder Adele A.
Published: September 2007

Typha latifolia and Carex rostrata both exhibit rhizospheric iron reduction after iron deprivation while Phragmites australis does not. Examination of T. latifolia and C. rostrata roots showed that these potential sites of iron uptake are surrounded by oxidized rhizospheres. Rhizospheric oxidation by T. latifolia, C. rostrata, and P. australis is more extensively distributed along the root than has been recorded in the past. All three species lower the pH of their rhizospheres: iron starvation increases the rate of acidification in T. latifolia and C. rostrata, but not in P. australis. Observation of the superimposition of oxidative rhizospheres over iron reduction sites supports the hypothesis that oxidation protects the root from reduced toxins. However, it is also possible that root oxidation may play a major role in nutrient procurement by hydrophytes.
An investigation of needle endophyte colonization patterns with respect to height and compass direction in a single crown of balsam fir (Abies balsamea)
Authors: Johnson J. A. , Whitney N. J.
Published: September 2007

All branches of a balsam fir (Abies balsamea (L.) Mill.) were removed and twenty 3-year-old needles from each branch were surface sterilized and placed on 2% malt extract media. There was a trend for obtaining more isolates of endophytic fungi at the bottom of the crown than at the top (r2 = 0.87). Phyllosticta sp. and Leptostroma sp. were isolated most often and were the most prominent by virtue of having more isolates for each branch sampled. No significant difference was found between compass directions for the four most frequently isolated species.
Magnitude, timing, and causes of immature fruit loss in Amelanchier alnifolia (Rosaceae)
Authors: St. Pierre R. G.
Published: September 2007

Despite a consistent and massive yearly bloom, the production of a fruit crop by Amelanchier alnifolia is highly variable. The objectives of this study were to characterize the magnitude and timing of fruit loss in A. alnifolia and to determine the causes of this loss, emphasizing factors that cause damage to flowers and immature fruit. Fruit loss was consistently of a large magnitude; for the 6 years that data were available, a mean of 81% of the potential fruit were lost. Mature fruit to flower ratios varied from 0.02 to 0.46 [Formula: see text]. The number of fruit per infructescence decreased within each season consistently and significantly. The period of decrease was initiated shortly after anthesis and was complete by mid-June, varying from 9 to 34 days [Formula: see text] in length. Fruit growth (mg dry weight) was only 16% complete by the end of the period of fruit loss. Of the abscised fruit collected and examined, a mean of 81% were damaged; 2–90% [Formula: see text] were damaged by a sawfly (Hoplocampa montanicola; Hymenoptera: Tenthredinidae) and 0–68% [Formula: see text] were damaged by frost. From 0 to 21% [Formula: see text] were damaged by other factors including a curculio (Anthonomus spp.) and unidentified insects and fungi. The cause of 19% of the total loss was undetermined.
The effect of plant age on asparaginase activity and amino acid levels in developing leaves of Pisum sativum
Authors: Sleciechowicz Konrad A. , Joy Kenneth W.
Published: September 2007

Asparaginase activity in young leaves of Pisum sativum was determined at various stages of plant development. Diurnal variation of asparaginase activity (with an increase in the light period) in emerging and half-expanded leaves was detected in young plants, but a much greater diurnal variation took place in young leaves of older plants. Levels of total α-amino nitrogen in both emerging and half-expanded leaves varied during the photoperiod (decreasing in the light) and there was a progressive decrease in overall levels in successive leaves at the same developmental stage; the most pronounced changes were noted in the levels of asparagine. The concentrations of asparagine and homoserine varied in xylem sap exudates, decreasing during the light period and also decreasing overall as plants aged. Since the activity of asparaginase in both emerging and half-expanded leaves is highest in mature plants, when levels of α-amino nitrogen are the lowest, the amount of asparaginase in developing pea leaves may be subject to a form of nitrogen catabolite repression by amino nitrogen supplied to, and present within, the leaf.
A histological study of apple roots affected by replant disease
Authors: Caruso Frank L. , Neubauer Benedict F. , Begin Marc D.
Published: September 2007

Little is known about the microscopical symptoms of roots from apple trees suffering from replant disease. Roots were sampled from healthy trees and from such diseased trees in four orchards from May until October. Roots were stained for the detection of mycorrhizal infection and other roots were fixed, dehydrated, embedded in paraffin, sectioned, and stained in safranin and fast green in order to elucidate morphological details. Healthy tree roots possessed considerably higher frequencies of mycorrhizal infection than diseased trees during the entire growing season. Arbuscules and hyphae were very common, vesicles were sometimes present, and possible chlamydospores of Glomus radiatum (Thaxter) Gerd. & Trappe were found in several samples. Whereas roots from healthy trees were structurally intact, roots from declined trees had extensive sloughing away of the epidermal and cortical layers and the cortical cells possessed significant amounts of densely stained material. Nematodes and possible hyphae of Rhizoctonia, Phytophthora, and Pythium were found in roots of declined trees. Althugh the stele of these roots appeared unaltered, hyphae were sometimes observed in the vascular elements.
Acid phosphatase, alkaline phosphatase, and nitrate reductase activity of selected ectomycorrhizal fungi
Authors: Ho Iwan
Published: September 2007

Seventeen isolates, encompassing five genera and eight species of ectomycorrhizal fungi, were compared for acid phosphatase, alkaline phosphatase, and nitrate reductase activity. Isolates within species differed in enzyme activity and isozyme patterns by host specificity and site (as exemplified by the genus Suillus). Host and site may have affected phosphatase enzyme activity. Generally, the Douglas-fir associates, which dominate in mesic sites, have higher acid phosphatase activity than pine associates, which mostly occupy xeric sites; however, pine associates from mesic sites also have higher acid phosphatase activity (e.g., S. tomentosus). In four isolates of Amanita muscaria, the effect of site was also apparent. Two of them, which have significantly higher acid phosphatase activity than the others, were isolated from mesic sites. The isozyme pattern of the genus Suillus appeared to be separated by host groups. Other isolates with only one species also differed more or less by host groups. They shared at least one band within host groups, except for the two isolates of Paxillus involutus from different hosts. The P. involutus S-403 isolated from an orchard showed much higher nitrate reductase activity than all other isolates. No apparent differences in nitrate reductase activity were found between the other isolates.
Ultrastructure of conidial germ-tube development in vitro by the insect pathogen Entomophaga aulicae
Authors: Murrin Faye , Nolan Richard A.
Published: September 2007

In an effort to understand the factors influencing the formation of infection structures by the insect pathogen Entomophaga aulicae, we examined the ultrastructural development of conidial germ tubes formed in vitro under conditions that resemble those producing appressoria and protoplasts during infection. Conidia germinated on formvar in a nonaqueous environment produced a single viable germ tube, which in turn produced appressorium-like structures or secondary conidia, structures similar to those formed on the host. The formation of appressorium-like structures indicates that stimuli for appressorium formation are relatively nonspecific, whereas development of the infection hypha requires different triggers. Conidia germinated in a liquid culture medium, which supports the growth of the protoplast stage of the fungus, produced a single viable germ tube that continued to grow apically. This apical growth was accompanied by the loss of the outer layer of the germ tube wall and the presence of electron-opaque granules in an extensive system of cytoplasmic membranes. Protoplasts did not form directly from these germ tubes and ultrastructural details of tip growth in this medium did not resemble those previously described in infection hyphae prior to protoplast formation in the host.
Peat chemistry of a continental mire complex in western Canada
Authors: Nicholson Barbara J.
Published: September 2007

A continental peatland complex in western Canada containing varied vegetational landforms was studied to relate surface physiognomy to peatland development. Peat chemistry was used to determine the influence of water chemistry on landform formation and to assess the development of ombrotrophy on forested Sphagnum islands. Surface water chemistry at the site showed the following: pH 3.7–6.3; calcium content 0.9–15.6 mg/L; magnesium content 0.5–2.8 mg/L; and reduced conductivity 0–232 μS/cm. Peat cores were subdivided into two peat types, fen and forested Sphagnum islands. Spearman rank correlations and the Mann–Whitney U-test were used to determine significant differences in ash, bulk density, calcium, and magnesium. Elemental contents of surface peats are directly related to landform features. Elemental peat profiles exhibit three accumulation trends: stable, increasing, and declining. Fen peats have profiles that are stable or increase towards the peat surface, whereas forested Sphagnum island peats have profiles that decline toward the peat surface. During the development of the mire, fen peats receiving mineral-enriched waters have accumulated higher amounts of mineral ions. Forested Sphagnum islands have developed in hydrologically sheltered areas, resulting in the formation of mineral-poor peat. Surface water, vegetation, and peat stratigraphy suggest that the forested Sphagnum islands have become ombrotrophic, forming local recharge zones with a gradual transition from a mineral-poor environment to ombrotrophy.
Pollaccia borealis sp.nov. associated with a purple-brown leaf spot of aspen
Authors: Funk A.
Published: September 2007

Pollaccia borealis sp.nov. is described from a purple-brown leaf spot disease of aspen (Populus tremuloides Michx.) in northern British Columbia and the Yukon Territory, Canada. Conidia were produced on malt agar at temperatures of 20–23 °C.
Developmental variation of cell wall degrading enzymes from cucumber (Cucumis sativus) fruit tissues
Authors: Miller A. Raymond , Dalmasso Joseph P. , Kretchman Dale W.
Published: September 2007

Variation of cell wall degrading enzyme activities and tissue firmness from the petal senescence to overripe stages of fruit development was studied in greenhouse-grown cucumbers (Cucumis sativus L. cv. Heinz 3534). Cucumbers exhibited a typical sigmoidal growth curve with a short lag phase (0–8 days after pollination) and extended log phase (8–28 days) followed by a stationary phase. Mesocarp firmness decreased between 10 and 20 days after pollination, then increased until 32 days after pollination. This decrease of mesocarp firmness was accompanied by increased activity of cellulase (3.5-fold), polygalacturonase (20-fold), pectin methylesterase (4-fold), and xylanase (9-fold). By contrast, carpel tissue firmness declined from 8–20 days after pollination, and remained low until 32 days after pollination. Only polygalacturonase and xylanase activities exhibited significant increases (5- and 6-fold, respectively) during softening of this tissue. Further, these peaks of enzyme activity in the carpel occurred 10 days before the corresponding peaks in the mesocarp. These data suggest that mesocarp and carpel tissues of cucumber soften by similar, but not identical mechanisms.
Design and evaluation of a remote-piloted aircraft spore sampler (REPASS) used over a cottonwood plantation
Authors: McCracken F. I.
Published: September 2007

Design of REPASS included a forward air intake to avoid sampling of turbulent air, an aspirated spore trap, stable flight, and simple construction. Specifications were as follows: length, 150 cm; wingspan, 183 cm; weight, 4.5 kg; power, 10 cc engine and airspeed, 25–85 km/h. A vacuum motor pulled air over 1–12 plastic rods at 0.106 m3/min. Single rods were seasonally exposed for 1 min at five altitudes to 62 m above ground over 97 ha of 1- to 2-year-old cottonwood near Fitler, MS. Fungus spore genera and quantity varied with altitude above ground and collection date. Spores of the genera Bispora, Cercospora, Epicoccum, Helminthosporium, Melampsora, Monilochaetes, Trichothecium and 12 other identified and some unidentified fungi were trapped during June to November. Total numbers of spores decreased as altitude increased. Spore genera decreased during November to May. A few Bipolaris sp. spores were collected in January. Urediospores of Melampsora medusae Thüm. were not trapped over 50 m above ground, after leaf fall, or in the spring. REPASS can meter spore density over crop trees within visual range of the operator.
The rust flora of Sino-Himalayan forests
Authors: Chen Mo-Mei
Published: September 2007

From 1975–1980, an investigation of rusts of the Sino-Himalayan flora was undertaken by an interdisciplinary research team of the Academia Sinica. The Sino-Himalayan plateau (Xizang) is a varied and unique physicogeographical region with combined effects of high altitude, vast expanse, and latitudinal position. A special category of montane (1000–6000 m) and its forest rust flora is proposed. This preliminary study of the hosts and their rusts includes 110 species and 26 genera in five families of rusts. According to biogeographical and ecological analysis, the Sino-Himalayan rust flora can be characterized as north temperate. This flora is classified into three zones: (i) the plateau zone; (ii) the temperate zone; and (iii) the subtropical zone. A distinct group of rust genera and species is found in each zone. The main genera and species recognized as Sino-Himalayan are also cosmopolitan in north temperate plateau regions. Sino-Himalaya rust flora mainly is a branch of East Asia flora and has close relationships with adjacent flora as well as with North American flora. This flora constitutes a potential source of rust diseases for forests in this and other regions.
Cytoembryology of Amaryllis hybrids
Authors: Khaleel Tasneem F. , Siemsen Daniel
Published: September 2007

Karyotype analysis, sporogenesis, and the development of gametophytes are described for four hybrids of garden Amaryllis. The basic chromosome number is x = 11, and all four hybrids are tetraploid. The basikaryotype, which consists of two median, five submedian, and four subterminal chromosomes, is traceable in four hybrids. The anther wall is five to six layered. The tapetum is of the secretory type, and its cells become two nucleate at the onset of meiosis in the microsporocytes. Bivalents, trivalents, and quadrivalents are formed during meiosis. The endothecial cells lack fibrillar thickenings. Pollen grains are shed at the two-celled stage. About 60–70% of the pollen grains are fertile. Ovules are anatropous and bitegmic. The archesporial cell may or may not undergo periclinal division. Development of the megagametophyte is monosporic in 90% of the ovules and bisporic in the remaining 10%. All four hybrids show degeneration of embryo sacs at various stages of development which accounts for the low percentage or lack of seed set.
Factors affecting the production of resting spores by Zoophthora radicans in the spotted alfalfa aphid, Therioaphis trifolii f. maculata
Authors: Glare Travis R. , Milner Richard J. , Chilvers Graham A.
Published: September 2007

Resting spore production by Zoophthora radicans (Brefeld) Batko in infected cadavers of the spotted alfalfa aphid, Therioaphis trifolii (Monell) f. maculata, varied according to a number of factors. For four isolates of the fungus tested, the proportion of cadavers containing resting spores was consistently greater at 10 °C than at higher temperatures. At 20 °C, a saturated atmosphere (100% RH) favoured resting spore production, and the proportion of infected cadavers that contained resting spores was nearly twice the amount of that at 95% RH. Individual isolates of the fungus were found to differ in their ability to form resting spores in infected cadavers; some formed resting spores in few or no cadavers, whereas others formed resting spores in many, under similar conditions. The ability to produce resting spores sometimes varied following serial culturing on solid media. Interestingly, resting spore production was found to correlate with inoculum density. Also, inoculation of aphids with two fungal isolates resulted in a marked increase in resting spore production compared with that of either isolate alone. It is presumed that some form of genetic combination is involved. Indirect evidence suggests that this is more likely to be cytoplasmic than nuclear in origin.
Effect of hydroperiod on seed-bank composition in semipermanent prairie wetlands
Authors: Poiani Karen A. , Johnson W. Carter
Published: September 2007

Bottom samples were collected from two semipermanent prairie wetlands to determine if known hydroperiod differences were reflected in seed-bank composition. Samples were also taken a 2nd year in one wetland to assess between-year variation. Seed density and composition were determined by counting and identifying seedlings that emerged from samples placed in a greenhouse. Most seed-bank characteristics were statistically indistinguishable between wetlands, including floristic composition and total seed density. A significant difference occurred, however, in the relative importance of mudflat annuals and émergents. The mudflat group was much more abundant in the wetland with the shorter hydroperiod (82 vs. 51%). More frequent exposure of the substrate probably yielded greater seed production. Also, a longer hydroperiod depressed seed density in the open water zone (open water zone, 1309 seeds/m2; two emergent zones, 2840 and 9893 seeds/m2). A seed-bank assay may detect subtle hydroperiod differences among wetlands of the same permanence class more quickly and economically than long-term hydrological monitoring. A sharp increase in mudflat seeds in the 2nd year of sampling after a drawdown supports the use of seed banks in determining hydroperiod events in these wetlands.
On Cryptosporella and Wuestneia
Authors: Reid James , Booth Colin
Published: September 2007

Wuestneia Auerswald (lectotype W.xanthostroma (Mont.) J. Reid & C. Booth n.comb.) is proposed as the correct generic name for fungi previously assigned to Cryptosporella Sacc. The genus is divided into the sections Wuestneia and Sordida n.sect. and 10 species and one variety are accepted including W.beltsvillensis (Petrak) n.comb., W.compta (Tul.) n.comb., W.farinosa (Ell.) n.comb., W.fusca (Nag Raj & DiCosmo) n.comb., W.guajavae (Kern) n.comb., W.paucispora (Pk.) n.comb., W.punctistoma (Ell.) n.comb., and W.tetraspora (Kobayashi) n.comb.; W.acericola n.sp., and W.xanthostroma var. dearnessii n.var. are described. Five new genera are proposed, Kensinjia (type K. umbrina (Jenkins) n.comb.), Kapooria (type K. musarum (Kapoor) n.comb.), Keinstirschia (type K. megalosperma (Kirsch.) n.comb.), Mebarria (type M. thujina (Nag Raj & DiCosmo) n.comb.), and Wehmeyera (type W. acerina (Wehm.) n.comb.). Thirty-three other fungi with names in Cryptosporella are discussed and, where possible, dispositions suggested; Botryosphaeria corynocarpi (Dias et da Camara) n.comb. and Diaporthe lentaginis (Rehm) n.comb. are proposed. Winterella hypodermia (Fr.) n.comb. is proposed, and Cryptosporella Sacc. is reduced to synonomy with Winterella O. Kuntze.
Elaphomyces spinoreticulatus sp.nov., with notes on Canadian species of Elaphomyces
Authors: Zhang Bin-Cheng , Minter D. W.
Published: September 2007

The status of the fungal genus Elaphomyces (Ascomycotina, Elaphomycetales) in Canada is reviewed with notes based mainly on collections in Kew from Nova Scotia made by K. A. Harrison in the 1950s. Elaphomyces anthracinus is reported for the first time from Canada and E. spinoreticulatus sp.nov. is described and illustrated. A key to the five known Canadian species of Elaphomyces is provided.
Inhibition of Botrytis cinerea spore germination by immunoglobulins
Authors: Gardiner R. B. , McKeen W. E. , Lawrence T. M. , Smith R. J. , Day A. W.
Published: September 2007

Lesion formation by spores of Botrytis cinerea on Vicia faba occurred within 15 h after inoculation. However, simultaneous application of various antisera delayed lesion formation until up to 65 h after inoculation. As the dilution of antiserum was increased, the length of the inhibitory period decreased and the fraction of the leaf surface that eventually became covered in lesions increased. Antisera of different antigen-binding specificity or different class of heavy chain (IgA, IgG, IgM) inhibited lesion formation, though IgM was the most effective. Antisera purified of other serum proteins were effective, but serum proteins such as albumins were not effective in causing inhibition of lesion formation. F(ab′)2 fragments of IgG molecules were as effective as the complete IgG molecule while Fc and light chain fragments were ineffective. Germination of B. cinerea spores on glass slides was inhibited by the same range of immunoglobulin molecules and fragments. We conclude that some constant portion of the antigen binding region of immunoglobulins inhibits lesion formation by inhibiting spore germination.
Survival of Endocronartium harknessii teliospores in a simulated airborne state
Authors: Chang Kan-Fa , Blenis P. V.
Published: September 2007

The effects of temperature and relative humidity (RH) on the survival of Endocronartium harknessii teliospores and the longevity of these spores out of doors during daylight hours were studied. In one experiment, fresh and liquid-nitrogen-stored spores of E. harknessii were impacted onto spider webs or plastic threads and incubated in darkness at temperatures of 6, 15, and 24 °C and RHs of 39 and 98%. Survival was measured after 1, 2, 4, 8, and 16 days. Spore longevity decreased with increasing temperature and was lower at 98 than at 39% RH. In a second experiment, spores were impacted onto spider webs and placed out of doors on clear days. Viability decreased linearly with time and averaged 33% after 12 h. The data suggest that E. harknessii has relatively good ability to survive in an airborne state and thus would have considerable potential for long distance spread.
Dynamics of Sorghum halepense seeds in the soil of an uncultivated field
Authors: Esso M. L. Van , Ghersa C. M.
Published: September 2007

The fate of a seed population of Sorghum halepense (L.) Pers. in the soil of an uncultivated area in Buenos Aires Province, Argentina (34°06′S, 60°25′W) was studied in terms of germination, decay, and losses due to seed predators. Seed dispersal significantly increased the seed density in the soil from December 30, 1981, until the end of March 1982. Thereafter, seed density decreased continuously until December 1982. This decay was well described by a negative exponential function. Germination and death of seed did not account for the decrease, but seed predation appeared to play the most important role in limiting the S. halepense seed population.
A comparison of variation of Pseudotsuga menziesii seedlings from genetically defined and undefined sources
Authors: Maze Jack , Banerjee Satindranath
Published: September 2007

Leader lengths were compared for seedlings (i) from full-sib families and (ii) of mixed genetic background 12 times over their second growing season. We wished to examine whether the variation in genetically defined groups was equal to, or less than, that from a genetically diverse background. Aside from one time, there was no difference in within-group variation for full-sib seedlings and for those of mixed genetic background. When variation was not equal, it was one of the full-sib families that was the most variable. This indicates that the high within-population variation in Pseudotsuga menziesii reflects crossing between highly variable individuals and not a complex mixture of half-sib families.
Taxonomic status of Fusicoccum amygdali and Phomopsis amygdalina
Authors: Tuset J. J. , Portilla M.A. T.
Published: September 2007

A comparative study was done in Spain of canker and withering of branches in almond and peach trees. Similar diseases of these fruit trees, described by several authors and attributed to Fusicoccum amygdali and Phomopsis amygdalina, suggests that these fungi are identical. Spanish isolates produced phialidic conidiogenous cells and occasionally β-conidia typical of the genus Phomopsis. A study of the type specimen of F. amygdali reveals that it also belongs in Phomopsis. Phomopsis amygdali (Del.) Tuset & Portilla comb.nov. is proposed to accommodate the fungus; Phomopsis amygdalina Canonaco is reduced to synonymy with it.
Corollospora armoricana sp.nov., an arenicolous ascomycete from Brittany (France)
Authors: Kohlmeyer Jan , Volkmann-Kohlmeyer Brigitte
Published: September 2007

A new marine fungus is described from rotting algae. Ascomata are attached to grains of sand and the curved ostiole is often hidden in the crust-like subiculum.
Differential tolerance of manganese among cultivars of Triticum aestivum
Authors: Macfie Sheila M. , Taylor Gregory J. , Briggs Keith G. , Hoddinott John
Published: September 2007

Thirty cultivars of Triticum aestivum differed in tolerance of manganese (Mn) as determined by relative root growth in solution culture. Based upon a root weight index (RWI = root weight in the presence of 500 μM Mn divided by control root weight), Mn tolerance ranged from 0.08 to 0.88. All Canadian Western Red Spring (CWRS) cultivars tested were Mn sensitive. Cultivars bred for high yield were more Mn tolerant, especially 'Norquay' (RWI = 0.88) which was the only cultivar with a RWI > 0.70. The cultivars 'Norquay' and 'Columbus' were selected as standards for Mn tolerance and Mn sensitivity, respectively. 'Norquay' showed maximum root growth at 100 μM Mn, a concentration which was toxic to 'Columbus', and differential tolerance was maintained up to 1000 μM Mn in solution. Differences between 'Norquay' and 'Columbus', grown in excess Mn, were also observed in the accumulation of biomass with time. In contrast with previous studies, Mn tolerance was positively correlated with Al tolerance (R2 = 32.7, p = 0.001) in the cultivars tested.
Small-scale succession towards fen on floating mat of a Typha marsh in Atlantic Canada
Authors: Mallik A. U.
Published: September 2007

In a Typha-dominated fresh water marsh, plant species composition was strongly influenced by the thickness of the floating organic mat. The "infilling" process was negatively correlated with pH (−0.63) and positively correlated (0.85 and 0.80) with the mat thickness and water table depth, respectively. The phytosociological tabulation of species cover data and the canonical correlation analysis of 14 environmental and plant variables arranged the 48 sampling quadrats into four groups, reflecting the seral stages towards the initial conditions of relatively stable fen formation. The buildup of undecomposed organic matter seems to be the driving force for the acidification, which is further intensified by the presence of Sphagnum and other bog-forming species.
Diadema
Authors: Shoemaker R. A. , Babcock C. E.
Published: September 2007

The new genus Diadema is described for six species of alpine pyrenomycetes from the Himalayas and western North America: Diadema acuta on Poa from California and on Trisetum from Kashmir, Diadema cincta on Carex from Punjab, Diadema curta on Biebersteinia (Gentianaceae) from Kashmir, Diadema hexamera on Poa from California, Diadema obtusa on Potentilla and Trisetum from Kashmir, and Diadema tetramera on various grasses and Juncus from California.
Vascular system of the fertile floret of Phalaris arundinacea
Authors: Pizzolato Thompson Demetrio
Published: September 2007

Six vascular bundles lie in two rows of three in the rachilla at the base of the fertile floret. Each bundle relates to a lemma or palea trace. As the rachilla bundles become traces they also produce sieve elements that interconnect to form the lower layer of the sieve-element plexus. Lodicule traces join the anterior of this lower plexus. Only the tracheary elements from the rachilla bundle related to the lemma's median trace rise higher in the rachilla, and these merge into a system of anomalous tracheary elements (xylem discontinuity) that rises toward the ovule. The lower sieve-element plexus layer ascends around the xylem discontinuity into a trilobed upper plexus layer which supplies the stamen traces. A third sieve-element plexus (pistil plexus) joins the upper plexus layer by three descending prongs. The pistil plexus, which occurs at the base of the pistil, is linked on its anterior to the anterior bundle. The placental bundle rises from the posterior of the pistil plexus and furnishes the sides of the pistil with their anterolateral and posterolateral sieve elements. The posterolaterals supply the styles. The sieve elements and the xylem discontinuity of the placental bundle supply the ovule.
Effect of temperature on melanization and myceliogenic germination of sclerotia of Sclerotinia sclerotiorum
Authors: Huang H. C. , Kokko E. G.
Published: September 2007

While sclerotia of the normal strain of Sclerotinia sclerotiorum produced on potato-dextrose agar at 7, 16, and 30 °C were black, the color of sclerotia of the aberrant strain was light brown, brown or tan, and dark brown or greyish black under 7, 16, and 30 °C, respectively. In the normal strain, deposition of melanin substance was heavy both on the surface and inside the cell walls of the rind of black sclerotia formed at 16 and 30 °C, but in sclerotia formed at 7 °C, many of the rind cells were unmelanized or partially melanized. In sclerotia from the aberrant strain, an electron-dense material, smaller than the melanin particles of the black sclerotia, was present in trace amounts or absent in light-brown sclerotia formed at 7 °C, but it was more abundant in dark-brown or greyish black sclerotia formed at 30 °C. Despite marked differences in color, sclerotia of the aberrant strain produced at the three temperatures were capable of undergoing myceliogenic germination on moist sand. It is concluded that temperature affects cell wall melanization during sclerotial morphogenesis, and that myceliogenic germination of sclerotia of S. sclerotiorum was affected by the black pigment but was unaffected by the color intensity of the brown pigment.
The effect of virulent and hypovirulent strains of Endothia parasitica on hydraulic conductance in American chestnut
Authors: Ewers Frank W. , McManus Patricia S. , Goldman Adam , Gucci Riccardo , Fulbright Dennis W.
Published: September 2007

Measurements of hydraulic conductance per unit length (Kh) were made on stems of Castanea dentata (Marsh) Borkh. that were inoculated with virulent and hypovirulent strains of Endothia parasitica and on stems with naturally occurring (wild) cankers. For stem segments infected with virulent strains (virulent infections), Kh values were significantly lower (p < 0.01) than in healthy control stems or in stem segments immediately above or below the canker. Adjacent segments were not significantly different from controls at the 0.05 level of probability. For hypovirulent infections, the Kh of canker segments, adjacent segments, and controls were not significantly different from one another. Dye ascents and descents indicated the xylem conductive area was sharply reduced in stem segments with virulent, but not hypovirulent, infections. Stem segments with wild virulent infections showed not only a reduction in xylem conductive area, but often a missing or incomplete outer xylem growth ring. Segments with wild hypovirulent infections often showed an incomplete outer xylem growth ring, with the intact portion of the outer growth ring (or rings) often quite swollen and sometimes with anomalous vascular bundles. It is concluded that xylem dysfunction is strongly correlated with reductions in Kh and with death of the leaves distal to virulent infections.
The effects of salinity and temperature on the germination of the inland halophyte Hordeum jubatum
Authors: Badger Kemuel S. , Ungar Irwin A.
Published: September 2007

The roles of temperature and salinity in controlling the germination of Hordeum jubatum were investigated. Germination is inhibited by simulation of warm summerlike thermoperiods. Seeds of H. jubatum will germinate at the time of dispersal if exposed to a favorable temperature regime. Seeds germinate readily at salinities higher than those favorable to growth and reproduction. Thus, germination is not the life-cycle stage that limits the distribution of H. jubatum along a soil salinity gradient. This pattern differs from that of other species at the study site and from many other halophytes. The germination response to salinity and temperature is enhanced after a cold treatment. Storage conditions significantly alter the germination of H. jubatum seeds when exposed to a gradient of constant temperatures. Discrepancies between the results of previous germination studies with H. jubatum could be due to the differences in seed handling procedures.
The systematics of Phytophthora sojae and P. megasperma
Authors: Faris M. A. , Sabo F. E. , Barr D. J. S. , Lin C. S.
Published: September 2007

Isolates of Phytophthora from alfalfa and soybean and the type isolate of Phytophthora megasperma Drechsler from hollyhock were compared morphologically, for temperature response, and pathogenically. Highly pathogenic, host-specific isolates from soybean and alfalfa, with relatively small oogonia, were identified as P. sojae Kaufmann and Gerdemann and divided into two formae speciales: f.sp. glycines and f.sp. medicaginis, respectively. Less pathogenic isolates from alfalfa with large oogonia were identified as P. megasperma and were compared favorably with Drechsler's original isolate and description. Isolates of P. sojae differed in their cardinal temperatures from those of P. megasperma. We consider P. sojae to be distinct from P. megasperma and propose that this taxon be reintroduced to the literature.
Localization of daphnetin and umbelliferone in different tissues of Daphne mezereum shoots
Authors: Zobel Alicja M. , Brown Stewart A.
Published: September 2007

The coumarins daphnetin and umbelliferone were detected in isolated tissues of Daphne mezereum stems and leaves and on the surface by analysis of extracts from brief dipping in almost boiling water. The surface had only low concentrations of these compounds compared with those of the whole leaf (≤ 0.1%). Daphnetin was always in higher concentration than umbelliferone, both in the whole leaf and in the whole stem. In isolated tissues daphnetin predominated, its concentrations being between 1.5 and 11 times as high as umbelliferone, except in the stem, where the xylem contained over twice as much umbelliferone as daphnetin. The highest concentrations of daphnetin were in storage tissues. The covering tissues, in almost all cases, contained the lowest concentrations of both daphnetin and umbelliferone.
All field-collected actinorhizae examined on Comptonia peregrina and Myrica pensylvanica in Maine are spore negative
Authors: Schwintzer Christa R.
Published: September 2007

The occurrence of spore-negative and spore-positive root nodules of Comptonia peregrina (sweet fern) and Myrica pensylvanica (bayberry) was examined in Maine, as well as the distribution of these nitrogen-fixing shrubs and selected characteristics of the environments in which they occur. Thirty-one widely distributed sweet fern sites were examined, and 16 of these were sampled intensively. The 16 sites were relatively open with < 30% tree cover, and their soil was coarse textured with pH ranging from 3.8 to 6.1. Bayberry nodules were examined at eight sites. All eight sites had the same characteristics as those of sweet fern except that soil pH ranged from 3.4 to 7.4. All nodules on both sweet fern and bayberry were spore negative. One possible explanation is host selection of spore-negative Frankia strains.
Reinstatement of the genus Haemescharia (Rhodophyta, Haemeschariaceae fam.nov.) for H. polygyria and H. hennedyi comb.nov. (= Petrocelis hennedyi)
Authors: Wilce R. T. , Maggs C. A.
Published: September 2007

The crustose red alga Haemescharia polygyna Kjellman, identified by comparison with unpublished drawings of type material, is a conspicuous element in the subtidal flora of the Canadian arctic and Greenland; it is the dominant noncoralline crust in these areas at depths from 3 to 46 m. Petrocelis hennedyi (Harvey) Batters, previously known only from northern Europe, is reported from Nova Scotia, Canada. These two species are remarkably similar in vegetative and reproductive characters, differing principally in the larger size of most structures in H. polygyna and the longer rows of tetrasporangia in P. hennedyi (up to 12, compared with a maximum of 6 (8) in H. polygyna). Accordingly, P. hennedyi is transferred to Haemescharia hennedyi (Harvey) comb.nov. The family Haemeschariaceae fam.nov. (Gigartinales) is proposed, based on the unique intercalary chains of obliquely cruciate tetrasporangia, and further characterized by the following: the crustose morphology of isomorphic tetrasporophytes and gametophytes; monoecious gametophytes forming lateral (1-) 2-celled carpogonial branches; carpogonia dividing after fertilization and producing up to 8 connecting filaments that fertilize identifiable intercalary auxiliary cells and give rise to simple carposporophytes from the point of junction between connecting filament and auxiliary cell.
Ultrastructural organization of freeze-substituted zoospores of Phytophthora palmivora
Authors: Cho Chung Won , Fuller Melvin S.
Published: September 2007

The ultrastructural organization of the zoospores of Phytophthora palmivora was examined using freeze substitution as a potential means of improving upon the images obtained with zoospores preserved by conventional chemical fixation. Despite die technical difficulties encountered, freeze substitution was effective in preserving the overall shape of the zoospores and membranous structures, including the plasma membrane, peripheral cisternae, and the water-expulsion vacuole. Coated pits, not previously reported on the plasma membrane of zoospores of fungi, were found in P. palmivora. The nucleus and cytoskeleton of zoospores were not as well preserved as with conventional chemical fixation. Unique features of freeze-substituted zoospores were compared with structures observed in previous studies of zoospores.