bluuebunny/crossref_metadata_2025 huggingface dataset:
Basal injury syndrome of Pinus needles
Authors: Rice P. M. , Carlson C. E. , Bromenshenk J. J. , Gordon C. C. , Tourangeau P. C.
Published: December 2009

Two types of macroscopic lesions, basal blister and basal necrosis, disrupting the surface tissues of Pinus needles under the fascicular sheath, are described in detail for the first time. In basal blister, hypertrophy and hyperplasia o mesophyll parenchyma cause an oval to elliptical bulge on the needle surface with a longitudinal split of the epidermal and hypodermal layers. In basal necrosis, the epidermal and hypodermal cells become necrotic, while the underlying mesophyll cells undergo structural disorganization. The causal agents are not known but in this study scale insects and deposition of airborne pollutants were associated with basal injury syndrome. The occurrence of basal injury symptoms increased with the age of the needles and the ambient concentration of acid rain precursors. The sulfur and fluoride concentration of the fascicular sheath also increased with the age of the foliage and the ambient pollutant concentrations. Basal injury on sites remote from strong sources of air pollution was significantly correlated with fascicular sheath sulfur concentrations within age-classes of older foliage. These remote site correlations occurred at basal injury rates and fascicular sheath sulfur concentrations lower than those typical of acutely impacted sites near strong sources of air pollution, and thus may represent a chronic impact resulting from acid deposition over wide geographic regions. A soft-bodied scale insect, Matsucoccus secretus Morrison, was often found under the fascicular sheath of Pinus ponderosa Dougl. ex Laws, but did not appear to be a primary cause of basal injury.
Two new genera of agarics based on Psilocybe corneipes and Phaeocollybia perplexa
Authors: Redhead S. A. , Smith A. H.
Published: December 2009

Two macroscopically similar species of agarics with the unusual combination of corneous stipes and pigmented basal mycelium are the types of two new genera. Mythicomyces is typified by Agaricus corneipes Fries, a species with roughened purple–brown basidiospores and brownish metuloidal hymenial cystidia. Stagnicola is typified by Phaeocollybia perplexa Orton, a species with smooth yellowish brown basidiospores and thin-walled cheilocystidia. Both types inhabit wet depressions in northern coniferous forests.
Cytological responses induced by five phytopathogenic fungi in a nonhost plant, Phaseolus vulgaris
Authors: Fernandez Myriam R. , Heath Michèle C.
Published: December 2009

Responses of the French bean plant (Phaseolus vulgaris L. cv. Pinto) to the nonpathogenic fungi Helminthosporium maydis Nisikado and Miyake (perfect stage Cochliobolus heterostrophus (Drechsler) Drechsler), Stemphylium sarcinaeforme (Cav.) Wiltish., S. botryosum Wallr., Cladosporium fulvum Cooke, and Uromyces vignae Barcl. were examined by cytological and histochemical techniques. All fungi penetrated bean leaves through stomata, and elicited similar modifications in guard and mesophyll cells. Responses involving cell contents were collapse, browning, autofluorescence, and a toluidine blue reaction indicative of the presence of phenolic compounds. Responses associated with cell walls were yellowing, autofluorescence, staining for phenolic compounds, and deposition of callose and of noncallosic, refractive material. In some of the interactions, decolorization and clearing of the tissue for light microscopy induced changes in the frequencies of autofluorescence of cell contents and walls when compared with those observed in fresh tissue. Despite the general similarity of responses elicited by each fungus, striking variations were found among fungi in the percentage of infection sites showing a particular response. For some responses, this variation seemed to be related to the type of interaction each of the fungi has with its susceptible host. It is suggested that even in nonhost plants, the nature and activities of the fungus determine the frequency and extent of the plant's responses. Also, it seems unlikely that all of these responses are involved in the cessation of fungal growth.
Silicon accumulation in fronds of the ostrich fern, Matteuccia struthiopteris
Authors: Aderkas P. von , Rogerson A. , Freitas A. S. W. de
Published: December 2009

Silicon accumulation in Matteuccia struthiopteris (L.) Todaro was investigated by electron microscopy and X-ray microanalysis. Silicon levels were highest in petioles of mature vegetative leaves, where it was restricted largely to the walls of epidermal and collenchymatous tissues. The pattern of silicon distribution within these walls was random and at no time were electron-dense aggregates of spherical particles observed. The absence of silicon from immature cells indicates that this element accumulated in vegetative cell walls during final stages of development. Moreover, the lack of silicon in lignified cell walls suggests that conditions suitable for lignification in ferns are incompatible with silicon deposition.
Environmental and physiological control of needle conductance for bare-root black spruce, white spruce, and jack pine seedlings on boreal cutover sites
Authors: Grossnickle Steven C. , Blake Terence J.
Published: December 2009

A study was conducted to examine the influence of environmental conditions of boreal cutover sites on plant water status and needle conductance of newly planted bare-root black spruce (Picea mariana (Mill.) B.S.P.), white spruce (Picea glauca (Moench) Voss.), and jack pine (Pinus banksiana Lamb.) seedlings. As absolute humidity deficit between the needles and air (AHD) increased, xylem pressure potentials (ψx) became most negative in black spruce, intermediate in white spruce, and least negative in jack pine seedlings. Needle conductance (gwv) was strongly related to AHD in all three species, with increasing AHD resulting in a decrease in gwv. However, at low levels of AHD, gwv values for black and white spruce seedlings were approximately 50 and 25% higher, respectively, than those for jack pine seedlings. For black and white spruce seedlings, gwv decreased as ψx became more negative, while jack pine gwv responded to more negative ψx with a threshold for stomatal closure at approximately −1.7 MPa. In all three species, increasing photosynthetically active radiation (PAR) resulted in greater gwv at all AHD levels. However, at high AHD levels, gwv, response to PAR was suppressed. The findings of this study indicate species differences in physiological response to atmospheric conditions under nonlimiting soil moisture conditions. The implications for successful reforestation are discussed.
Étude des capacités d'échange et des sélectivités cationiques de parois isolées des racines de Cochlearia anglica et de Phaseolus vulgaris cultivés sur des milieux diversement salés
Authors: Bigot J. , Binet P.
Published: December 2009

Cochlearia anglica L. (halophyte) and Phaseolus vulgaris L. (glycophyte) were grown in media of different salinities. The root cell walls were isolated and then equilibrated with various salt solutions. There were differences between cell walls from C. anglica and P. vulgaris in both the cationic exchange capacity (computed by the sum of parietal cations) and the cell wall selectivity (evaluated by the centesimal proportion of each cation). In cell walls from plants grown without NaCl, the number of exchange sites was greater for the halophyte than for the glycophyte. Growing the plants on 42 and 85 mM NaCl medium reduced or reversed the disparities between the two species: with C. anglica, the cell wall cationic exchange capacity decreased when the growth medium salinity increased whereas this capacity tended to rise for P. vulgaris. However, the culture medium salinity did not affect the cell wall selectivity of these species for major cations. For Ca2+, the selectivity of cell walls from P. vulgaris was higher than that of cell walls from C. anglica; for the other cations, the situation was reversed.
Changes in transfer cell distribution in the ovule of soybean after fertilization
Authors: Folsom M. W. , Cass D. D.
Published: December 2009

The presence of transfer cells in various regions of the postfertilization ovule of soybean is described. A developmental study shows that transfer cells, occurring in the micropylar nucellus, are formed after fertilization but destroyed by expansion of the embryo sac during transition from the zygote to the two-celled embryo. Subsequently wall ingrowths appear in five additional sites: (i) in the region where the embryonic basal cell wall is associated with the degenerated synergid, projecting into the basal cell; (ii) on the chalazal embryo sac wall projecting into the central cell; (iii) on the embryo sac wall projecting into the basal cell; (iv) on common walls of micropylar suspensor cells; and (v) on some cell walls at the micropylar end of the inner integuments. It is our opinion that these transfer cells are all involved in augmenting metabolite transport and that their orderly appearance in different areas of the ovule signifies changes in the nutritional environment of the young embryo and endosperm of soybean. Because these transfer cells are closely associated with the embryo sac wall, it is proposed that this wall is a common apoplast functioning as both a sink for metabolites from the nucellus and source for all solutes taken up by the cells of the embryo sac.
Plantlet formation in black and white spruce. II. Histological analysis of adventitious shoot formation in vitro
Authors: Rumary Colin , Patel Kamlesh R. , Thorpe Trevor A.
Published: December 2009

Histological analysis of developmental events during adventitious shoot formation in cultured epicotyl explants of black and white spruce was carried out. Cells towards the periphery of the expiants and between the bases of the cotyledons responded to cytokinin and became meristematic. Cell division in these regions led to the formation of meristemoids and ultimately intercotyledonary adventitious shoots. These shoots developed a vascular system, which became connected to the main vascular system of the expiant. After about a month of culture, the entire expiant became meristematic and showed evidence of additional de novo shoot development. Several rings of bud primordia were found at the periphery of the expiant after about 40 days of culture. These primordia that developed in the subepidermal layers could easily be distinguished from the surrounding cells by their distinct boundaries and intense staining for nucleic acids and proteins. After 2 months of culture, the entire expiant was covered with well-developed shoots having organized apical meristems, needle primordia, and vascular systems.
Restriction of a C3 grass to dry ridges in a semiarid grassland
Authors: Gurevitch Jessica
Published: December 2009

Contrary to generalizations about differences in the adaptive significance of C3 and C4 photosynthesis, Stipa neomexicana, a C3 grass, was restricted to the driest sites along a topographic and soil moisture gradient in a semiarid grassland in Arizona. The distribution of Stipa neomexicana was inversely related to the abundance of C4 grasses. The total biomass of C4 grasses increased from low values on ridge crests to maximum values on lower, wetter sites. Ordination analysis confirmed that the topographic and soil moisture gradient was the factor most closely associated both with grass species distributions and with total biomass and cover. Other factors, such as soil fertility, did not appear to be closely related to vegetation patterns. The data suggest that Stipa neomexicana was excluded from sites with greater soil moisture by competition with C4 neighbors. While it is likely that other factors besides photosynthetic type determine the ability to survive on the driest sites in this system, C4 photosynthesis appears to confer an advantage in competitive ability in microhabitats with greater amounts of soil moisture.
Thermophilous fungi in Port Blair soils
Authors: Singh S. , Sandhu D. K.
Published: December 2009

Soils were collected from eight different sites of saline marshy soils of Port Blair situated in the Andaman and Nicobar islands, India. A total of 93 333 colony-forming units representing 46 species of thermophilous fungi were isolated by the soil dilution method. The fungi were tabulated in order of ecological importance based on their frequency, relative density, and presence in the selected sites of this study. This is apparently the first study of these fungi from the Port Blair soils. Of the 46 species, Mucor miehei, Rhizopus oligosporus, Thermoascus crustaceous, T. thermophilus, and Trichoderma pseudokoningii are new records for India and Acremonium terricola, Aspergillus acculeatus, A. nidulans var. latus, and Sporotrichum thermophile are isolated from Indian soils for the first time. The temperature responses of the fungi revealed 14 microthermophiles and 22 thermotolerant and 10 true thermophilic species. Thirteen species of thermophilous fungi have been reported in addition to those already recorded in the literature.
Effects of habitat and size of fruit display on removal of Smilacina stellata (Liliaceae) fruits
Authors: Piper Jon K.
Published: December 2009

The effects of habitat and infructescence size on fruit removal by birds and grazing mammals from artificial infructescences of Smilacina stellata (L.) Desf. were examined. The study site, a coniferous forest in the Blue Mountains of eastern Washington, differed from sites previously examined for bird – fruit interactions in North America in that autumnal censuses for 3 years indicated numbers of avian frugivores were lower. Removal of fruits from infructescences in light gaps was consistently faster than was removal from infructescences placed along forest edge or beneath dense canopy. Larger fruit displays influenced removal along forest edge only. The greatest percentage seed loss to grazing mammals occurred generally in the largest fruit displays and in those infructescences under a closed canopy. The results suggest that levels of seed dispersal and seed predation in understory plants differ in light gaps, forest edges, and habitats beneath forest canopy.
Hybridization studies in the genus Impatiens
Authors: Merlin Catherine M. , Grant W. F.
Published: December 2009

The biosystematic relationships of Impatiens walleriana Hook. f. and other selected species were examined by means of hybridization experiments and cytological techniques. Both I. gordonii Home and I. usambarensis Grey-Wilson hybridized with I. walleriana. Meiotic abnormalities of the hybrids were determined by examining pollen mother cells. Meiosis was regular in the majority of cells in both of the hybrids, but I. walleriana × I. gordonii had more abnormalities than I. walleriana × I. usambarensis. Because of the meiotic abnormalities in the hybrids and the morphological differences between I. walleriana and I. gordonii, I. gordonii was confirmed as a distinct species. The status of I. usambarensis was not as clear because it was morphologically similar to I. walleriana, and the hybrid between the two species had fewer meiotic abnormalities. Both I. gordonii and I. usambarensis could be useful in a horticultural breeding program because they hybridize easily with I. walleriana.
Increased papilla formation, a major factor of induced resistance in the barley – Erysiphe graminis f.sp. hordei system
Authors: Sahashi N. , Shishiyama J.
Published: December 2009

Using two barley cultivars, 'Hanna' and 'Russian No. 12', resistance to Erysiphe graminis DC. f.sp. hordei Em. Marchal induced by preliminary inoculation with a compatible or an incompatible race of the powdery mildew fungus was examined with respect to cellular responses. When the primary leaves of barley seedlings were preliminarily inoculated with a compatible or an incompatible race on the abaxial leaf surface, they became resistant to the disease caused by challenge inoculation with the same pathogen on the adaxial surface. The resistance induced was expressed as decrease of fungal penetration and restriction of hyphal growth. These phenomena seemed to be attributable to the increase of papillae or papillalike structures which do not seem to be responsible for the race-specific resistance. On the basis of these results, it is suggested that the resistance induced may be different from race-specific resistance.
Evidence for homothallism and vegetative compatibility in southern Diaporthe phaseolorum
Authors: Ploetz R. C. , Shokes F. M.
Published: December 2009

Twenty-nine vegetative compatibility groups (vcgs) were identified among 297 isolates of the fungus causing soybean stem canker in the southeastern United States (southern Diaporthe phaseolorum). Of the isolates characterized, 79% were from one of the vcgs described (group 1). Barrage zones formed between isolates from different vcgs when grown on potato dextrose agar, and also formed, but not always distinctly, on cornmeal agar, Czapek-Dox agar, lima bean agar, and malt agar; barrages did not form on Sach's agar or water agar. Two types of evidence suggested that southern D. phaseolorum is homothallic. Perithecia and viable ascospores were produced by single ascospore isolates, and ascospores produced by mass isolates were always of the same compatibility group as the parental mass isolate.
A new species of Anixiopsis
Authors: Guého Eveline , Vroey Charles De
Published: December 2009

Anixiopsis biplanata sp.nov. is described as a new ascomycete isolated from soil at an altitude of 3100 m in Nepal. It is heterothallic and characterized by small, reddish brown ascospores (4 × 3 μm), which under the light microscope seem subrectangular to hexagonal in side view and appear smooth walled. Under the scanning electron microscope, however, they are tire shaped, ornamented with an equatorial reticulum and with two smooth, flat, lateral discs. Its anamorph is a Chrysosporium. Anixiopsis biplanata is briefly compared with the three other species already included in the genus Anixiopsis Hansen.
Abscisic acid content and components of water status in leaves of Populus deltoides
Authors: Lin Tsai-Yun , Sucoff Edward , Brenner Mark
Published: December 2009

The relationship between abscisic acid (ABA) and leaf water status was studied during the air drying of detached leaves of eastern cottonwood (Populus deltoides Marsh.). The ABA content increased exponentially as leaf water potential and leaf turgor potential decreased. No clearly defined thresholds were observed between ABA content and these variables. ABA content was linearly related to the relative fresh weight and was not related to the osmotic potential.
Postglacial vegetation and climatic change in the upper Peace River district, Alberta
Authors: White James M. , Mathewes Rolf W.
Published: December 2009

Pollen analysis and radiometric dating of sediment cores from two lakes in the Saddle Hills, Peace River district, Alberta, were used to investigate postglacial vegetation and climatic change. A poplar – willow – sage – grass – sedge zone began about 11 700 ± 260 years BP. A distinct pine and spruce rise indicates the local presence of conifers. Peace River spruce could have served as a source for spruce in the Yukon, transported by glacial meltwater conceivably as early as about 11 100 years BP. A paper birch rise and spruce decline between about 8700 and 8200 years BP is likely due to fires during a period of enhanced seasonality. It is suggested that subsequent weakening of the anticyclone associated with the Laurentide ice lengthened the growing season, permitting pine to be the major fire successor to spruce. During the pine peak ca. 7400 years BP there was no grassland over the Saddle Hills, so the Peace River grasslands cannot be explained as Hypsithermal relict vegetation. Conditions similar to the present were apparently reached by about 5000 years BP.
Production de plantes haploïdes de Gerbera jamesonii par culture in vitro d'ovules
Authors: Ahmim Mamar , Vieth Joachim
Published: December 2009

Unfertilized ovules of Gerbera jamesonii were cultivated in vitro and haploid plants were successfully regenerated. Five concentrations of sugar, and four hormonal combinations containing indole acetic acid and benzyl adenine were tested. The best results were obtained with 0.1 mg indole acetic acid/L and 0.2 mg benzyl adenine/L; 1% sugar in the medium was sufficient for callus production and regeneration of plantlets from the clone of the experimental cultivar, 'Super Gerbera'. One hundred and fifty ovules per capitulum can be cultivated and under optimal conditions a frequency of 5% haploid plantlets can be obtained.
Pathogenicity of postfire ascomycetes (Pezizales) on seeds and germinants of lodgepole pine
Authors: Egger Keith N. , Paden J. W.
Published: December 2009

Forty isolates of postfire ascomycetes (Pezizales) were tested for in vitro pathogenicity on seeds and germinants of lodgepole pine, Pinus contorta Dougl. Two known pathogens, Caloscypha fulgens (Pers.) Boud. and Botrytis cinerea Pers., were included as a check of the method. Caloscypha fulgens was the only fungus that caused serious declines in seed germination, although several species of postfire Pezizales were capable of preemergence seed infection. Rhizina undulata Fr. and Pyropyxis rubra (Peck) Egger were strongly pathogenic on germinants. Pyropyxis rubra was not previously known to be pathogenic. Many isolates were weakly pathogenic on germinants under the conditions tested.
Temperature and photoperiod responses of soybean embryos cultured in vitro
Authors: Raper Jr. C. David , Patterson Robert P.
Published: December 2009

Temperature and photoperiod each have direct effects on growth rate of excised embryos of soybean (Glycine max (L.) Merrill). To determine if the effects of photoperiod are altered by temperature, embryos of 'Ransom II' were cultured in vitro at 18, 24, and 30 °C under photoperiod durations of 12 and 18 h at an irradiance of 9 W m−2 (700 to 850 nm) and a photosynthetic photon flux density of 58 μmol m−2 s−1 (400 to 700 nm). Accumulation rates of fresh and dry weight were greater under 18-h than 12-h photoperiods over the entire range of temperature. Water content of the cultured embryos was not affected by photoperiod but was greater at 18 and 30 than 24 °C. The accumulation rate of dry weight increased from 18 to 26 but declined at 30 °C.
Induction of bolting by gibberellic acid in rosettes of diffuse (Centaurea diffusa) and spotted (C. maculosa) knapweed
Authors: Upadhyaya Mahesh K.
Published: December 2009

An attempt was made to induce synchronous bolting of knapweed (Centaurea spp.) rosettes with gibberellic acid (GA3) under greenhouse conditions. Single or double (2 weeks apart) sprays of GA3 (0, 0.3 × 10−4, and 1.5 × 10−4 M) were applied to 10- to 115-day-old diffuse knapweed (C. diffusa Lam.) rosettes. With the exception of 10- and 25-day-old rosettes, highly synchronous bolting was induced by double applications of 1.5 × 10−4 M GA3. Bolted plants flowered within 8 to 10 weeks of treatment but did not form seeds because of the absence of pollinators in the greenhouse. The size of bolted plants and the percentage of plants bearing flowers depended on rosette age at the time of GA3 application. With a single GA3 application or with two applications at lower concentration, uneven and (or) irregular bolting occurred. Occasionally, the initial rapid stem growth induced by GA3 was arrested, resulting in the formation of aerial rosettes. GA3 also induced bolting in spotted knapweed (C. maculosa Lam.). Induction of synchronous bolting may be useful in mechanical, biological, and (or) environmental (e.g., winter-killing) control of biennial weeds. Its feasibility under field conditions, however, remains to be demonstrated.
Arsenite toxicity and arsenite tolerance in the cyanobacterium Synechococcus leopoliensis
Authors: Budd K. , Casey J. R. , MacArthur J. D.
Published: December 2009

Sodium arsenite at concentrations above 50 μM inhibited the growth of Synechococcus leopoliensis UTEX 625 in a defined culture medium. Inhibition was transitory, with growth resuming after a lag period the duration of which depended on the arsenite concentration. Cells grown for several hours in the presence of 10 μM arsenite became tolerant to concentrations of arsenite that inhibited the growth of untreated cells. Neither sensitive nor tolerant cells chemically modified the external arsenite detectably within the experimental period. At a concentration of 200 μM, arsenite temporarily halted growth of sensitive cells but did not affect that of tolerant cells. This concentration of arsenite inhibited net photosynthesis in both sensitive and tolerant cells. At the same time it selectively decreased the incorporation of carbon in the light into α-amino acids, especially glutamate, in sensitive but not in tolerant cells. Simultaneously, incorporation of carbon into pyruvic acid markedly increased. The activity of the partially purified pyruvate dehydrogenase complex of S. leopoliensis was abolished by 45 μM arsenite. It is concluded that inhibition of pyruvate dehydrogenase by arsenite is sufficient to explain its inhibition of growth in this organism.
Distribution of uranium series radionuclides in upland vegetation of northern Saskatchewan. I. Plant and soil concentrations
Authors: Sheard J. W.
Published: December 2009

Levels of lead-210, polonium-210, radium-226, and uranium are reported for 10 plant species (2 conifer, 4 shrub, 3 lichen, and 1 moss species) and soils in northern Saskatchewan. Two localities were studied in each of two regions, one uraniferous, the other not. Nonvascular species showed the highest levels of lead-210, polonium-210, and uranium, and the shrubs, the highest levels of radium-226. The lichen and moss species show no significant difference in accumulation of lead-210 and polonium-210 among regions, reflecting the assumed atmospheric distribution and particulate accumulation of these radionuclides. Seven of eight species for which comparisons could be made showed significant differences in uranium accumulation among regions. High levels in the lichen and moss species suggest that the primary source of uranium in these species is not directly from the soil. In contrast to the other radionuclides, radium-226 only showed significant differences among localities within regions, this being due to high accumulations occurring at one locality in the nonuraniferous region.
Vegetation–elevation correlation in two dyked marshes of northeastern Vancouver Island: a multivariate analysis
Authors: Bradfield Gary E. , Campbell Alison
Published: December 2009

Vegetation – substratum elevation relationships in the Kokish and Cluxewe tidal marshes on northeastern Vancouver Island were examined using principal components analysis, canonical correlation analysis, and multivariate analysis of variance. Both marshes have similar undyked vegetation with low-elevation Carex lyngbyei dominated stands and higher elevation mixed-grass swards of Festuca rubra, Deschampsia cespitosa, Hordeum brachyantherum, and Agrostis stolonifera. Dyked areas were less comparable in their vegetation as a result of a variety of disturbances in the past. Elevation showed a stronger connection with Continuous compositional change in undyked than in dyked areas, but less than half of the total vegetation variation was explained. Plant community classifications, based on aerial photographs, accounted for high proportions of the total vegetation variation (87–99%) and residual variation (62–97%) remaining after the "effect of elevation" had been removed from the vegetation data, using regression analysis. This suggested that the plant communities recognized are distinct units but that factors unrelated to elevation are mainly responsible for their formation.
Influence of increasing elevation on growth characteristics at timberline
Authors: Hansen-Bristow Katherine
Published: December 2009

Significant differences in growing-season air and soil temperatures were found with increasing elevation in the upper montane and forest–alpine tundra ecotone. Temperature inversions in topographic depressions were frequent, especially during the growing season. Variability in bud flush timing with elevation was best accounted for by soil temperatures; however, air temperature recorded within a mat conifer also correlated well with bud flush timing. Significant differences in shoot elongation, needle length, and cuticular thickness were found with differences in climate and elevational changes.
Molecular forms and kinetic properties of the mitochondrial fraction of NAD-malate dehydrogenase in four clones of Lathyrus japonicus (Leguminosae) from sites of contrasting climates
Authors: Simon Jean-Pierre
Published: December 2009

The molecular forms and kinetic properties of the mitochondrial fraction of NAD-malate dehydrogenase (mt-MDH) were analyzed in four clonal populations of Lathyrus japonicus collected from sites of contrasting climates in eastern North America and acclimated to three experimental thermoperiods. Three molecular forms of mt-MDH were separated in eight different starch and acrylamide electrophoretic systems, and isoelectric focusing (IEF) disclosed nine isozymes with isoelectric points in the 6.7–8.2 pH range. No differences in the electrophoretic or isoelectric focusing patterns were observed between clones acclimated to any of the three thermoperiods. Apparent Km values and Vmax/Km ratios for oxalacetate were obtained at 14 assay temperatures ranging from 2.5 to 35 °C. Km values were lower in the 10–20 °C range and increased markedly at higher and, particularly, at assay temperatures below 10 °C. Acclimation had a marked effect upon Km values obtained at extreme assay temperatures. Km values were significantly higher for assays in the range of 30–35 °C for plants of the two cold-adapted clones grown at 7–15 °C and 15–25 °C. Vmax/Km ratios were lower over the 30–35 °C segment of the assay curve for mt-MDH of the two cold-adapted clones acclimated at 7–15 °C and 15–25 °C and acclimation modified the shape of the curves of Vmax/Km ratios for mt-MDH from the four clones. Results suggest that modifications in kinetic behaviour of mt-MDH among Lathyrus japonicus clones represent adjustments for the modulation of catalysis in response to temperature conditions at the original sites of collection of the clones.
Evidence for heterogeneity in the carbohydrate moieties of peroxidase isozymes from two environmentally induced flax genotrophs
Authors: Gaudreault Pierre-Richard , Tyson Hugh
Published: December 2009

The corresponding isoperoxidases from the flax genotrophs L and S have different molecular weights. Utilizing affinity chromatography on Sepharose-bound concanavalin A, we have shown that this lectin has a stronger affinity for the isoperoxidases purified from S stem tissue than those from L. The presence of differences in the carbohydrate composition of L and S peroxidases was confirmed when it was observed that only S peroxidases were susceptible to digestion by endo-β-N-acetylglucosaminidase H. Glycoprotein-enriched fractions were then purified from L and S stem tissue. The results showed that most glycoproteins of S origin have higher molecular weights than their L counterparts. Certain glycoproteins were digested by endo-β-N-acetylglucosaminidase H only if they were of S origin, while others were digested regardless of their origin. In both cases, the original differences in molecular weight between L and S glycoproteins were eliminated. These results support our view that posttranslational modification at the level of the carbohydrate chains of the L and S peroxidases is the reason for their heterogeneity on polyacrylamide gels.
Is there a relationship between tracheary element formation and lignification in soybean (Glycine max var. Wayne) callus cultures?
Authors: Miller A. Raymond , Roberts Lorin W.
Published: December 2009

The possible relationship between tracheary element number and lignin content was studied in cultured soybean (Glycine max L. var. Wayne) cotyledon callus. Callus initiated on 4.5 μM 2,4-dichlorophenoxyacetic acid contained 3.0 × 104 tracheary elements per gram fresh weight and 41 μg lignin per milligram dry weight after 10 days incubation, and these values did not vary significantly after two subsequent transfers (7 days each) to a medium containing 0.1 μM α-naphthaleneacetic acid and 0.01 μM kinetin. Transfer of this callus to a medium supplemented with 60 μM indole-3-acetic acid and 0.5 μM kinetin resulted in significant increases in tracheary element number and lignin content (290 and 56%, respectively). A time-course study revealed that both tracheary element number and lignin content reached a maximum 5 to 6 days after transfer to the medium containing indole-3-acetic acid and kinetin. However, when total callus lignin content was plotted against total tracheary element number, no statistically significant relationship was found. The formation of lignin not associated with tracheary elements may have been a factor. These results indicate that the induction of tracheary element formation and lignification in soybean callus have similar hormonal requirements, but lignification occurs independently of tracheary element formation in this system.
Abscisic acid and low temperature induced polypeptide changes in alfalfa (Medicago sativa) cell suspension cultures
Authors: Robertson Albert J. , Gusta Lawrence V.
Published: December 2009

Changes in extracellular, cellular, and subcellular proteins during abscisic acid and low temperature induced cold hardening of alfalfa (Medicago sativa L. cv. Wisconsin 22C) cell suspension cultures were investigated by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Extracellular proteins from 4- to 6-day-old ABA and low temperature grown alfalfa cells showed decreased electrophoretic mobilities, lacked a 190-kDa glycoprotein, and had reduced amounts of four other polypeptides. In total cell protein analyses, a 42-kDa protein was enriched in both ABA and low temperature treated alfalfa cells. Several proteins increased or induced by exogenous ABA treatment were identified in the extracellular (12.5 and 13 to 15 kDa), total cell and cell wall (24 kDa), and soluble (20, 37, and 41 kDa) fractions. However, no major protein changes were resolved by one-dimensional electrophoretic analyses of crude membrane proteins.
Le système endophytique d'Arceuthobium oxycedri. II. Aspects ultrastructuraux des zones de contact entre les tissus de l'hôte et du parasite
Authors: Sadik A. , Rey L. , Renaudin S.
Published: December 2009

Ultrastructural study of the contact areas between the endophytic system of Arceuthobium oxycedri and the tissues of its host, Juniperus oxycedrus, shows that a crushed zone often occurs around the large cortical strands and along the primary sinkers in the secondary phloem of the host; such a structure seems rather unfavourable to the transfer of substances. On the other hand, the presence in the secondary xylem of half-bordered pits in direct contact with the cells of the primary and especially secondary sinkers certainly makes it easier for exchanges to take place. At the tip of the sinkers, the cells of the parasite, in the course of their growth, damage the cells of the host and sometimes penetrate into the lumen of its tracheids. Electron microscopy shows important acid phosphatase and ATPase activities at the level of the plasmalemma, plasmodesmata, and also some small endo- or exo-cytotic vesicles in the primary and secondary sinkers. Such activities are a sign of intense active transfer processes in these parts of the endophytic system. Around the contact zones, the parenchymatous cells of the host become very similar in aspect to those of the parasite.
La surface foliaire, déterminant du développement chez le Soja (Glycine max). Régulation inter-compartiments tige principale – rameaux
Authors: Barthou H. , Buis R. , Chanier P.
Published: December 2009

Systematic early reduction of two-thirds of the surface of each leaf on the main stem in soya results in (i) a decrease, on the main axis, in the number of leaves formed and the total number of pods, with no change in the rate of phyllogenesis; and (ii) a stimulation of the development of axillary branches which compensate the foliar and reproductive deficit of the main stem through their growth, their leaf surface area, and the number of pods they form. For given growth conditions, it was shown that, to a certain extent, global production (vegetative and reproductive) is maintained at a constant level by compensation processes between the main stem and the branches. The existence of such relations between compartments has regulatory importance for the development of the whole plant. [Translated by the Journal]
Ébauches intracytoplasmiques de grains protéiques dans des cotylédons de Raphanus en développement
Authors: Genevès Louis , Rutin Jacques
Published: December 2009

Protein bodies were characterized at an early stage of their maturation in thin green cotyledons of developing radish embryos. They appeared as granules in the cytoplasm of meristematic cells. Their diameter (0.5 to 1 μm) was in the range of that of mitochondria. They were distinguished from vacuoles by their morphology, size, and structure. Some appeared to be associated with cisternae of endoplasmic reticulum or dictyosomes (permanganic fixations). Their evolution was synchronous in the cell and also in the cotyledonary tissue. Compact in appearance, they were constituted of thin packed fibrillar structures, limited by a denser peripheral layer. It is difficult to know whether or not they had a limiting membrane. Some possessed thin dense crystals or globoids (aldehydic fixations). During this early phase, several types of organelles seemed to contribute to the development of protein bodies, including saccules of rough endoplasmic reticulum and dictyosomes. Polyribosomes constituted a network around their surface. They did not exhibit any acid phosphatase activity. In this respect, they differed from the vacuoles, saccules of endoplasmic reticulum, and several neighbouring vesicles.
A demographic analysis of Rubus idaeus and Rubus pubescens
Authors: Whitney Gordon G.
Published: December 2009

The population dynamics of Rubus idaeus L., a colonizer of disturbed sites, and R. pubescens Raf., an inhabitant of damp woodland areas, were compared in a series of permanent plots. Disturbed site conditions trigger the germination of R. idaeus and give rise to predominantly even-aged stands of this species. The half-life of the shade-intolerant aboveground population is approximately 3 years. The species' ephemeral aboveground existence, however, is more than balanced by the very low decay rate of its large seed bank, i.e., the belowground population has a half-life in excess of 20 years. Stands of R. pubescens, by way of contrast, are characterized by a diverse age structure and a long half-life of 10–20 years. An extended period of existence above ground is coupled with a small and transient seed bank below ground. Less than 15% of the seeds survive for more than 1 year.
Life history and taxonomy of two populations of ligulate Desmarestia (Phaeophyceae) from Chile
Authors: Ramirez M. E. , Müller D. G. , Peters A. F.
Published: December 2009

Two populations of broad-bladed (ligulate) Desmarestia from central and southern Chile were studied in laboratory cultures. They differ in sporophyte morphology and gametophyte characters (monoecism versus dioecism). The dioecious population is found to be related to D. firma from South Africa and D. munda from the northeast Pacific, while the taxonomic status of the broad-bladed monoecious population is left undetermined. In both populations sporophytes originate after fertilization as well as by apomixis. Chromosome numbers alternate between ca. 23 and ca. 46. Evidence is presented that spermatozoids of the dioecious Desmarestia can develop into sporophytes (androgenesis or ephebogenesis).
Effet de l'état du phytochrome sur l'efflux de solutés des disques de limbes foliaires de cotonnier
Authors: D'Aoust A. L. , Hubac C.
Published: December 2009

Solute leakage from leaf discs of cotton plants treated for activation or deactivation of phytochrome was measured by conductivity changes of the bathing solution. The treatments lasted 15 days, and were as follows: (i) short day (9 h of light), (ii) short day with red light favouring the activation of the phytochrome, and (iii) short day with far-red light favouring the deactivation of the phytochrome. The activation of the phytochrome by red light caused a significant increase of leakage of electrolytes from the leaf discs into the bathing solution, while its deactivation by far-red increased retention of electrolytes. Dry weights of leaf discs were not modified by the duration of the treatment. The hypotheses of membrane permeability and (or) of the difference in accumulation of electrolytes as affected by the state of the phytochrome in the leaf are discussed. [Translated by the journal]
Variation of mycelial morphology between species and formae spéciales of rust fungi of cereals and grasses
Authors: Niks R. E.
Published: December 2009

The morphology of the infection structures (substomatal vesicles, primary infection hyphae, and haustorial mother cells) was described for 23 isolates comprising nine rust species of cereals and grasses. Interspecific differences in morphology were very large. The results indicate that it should be possible to identify single sporelings at least to species level. Between samples of the same rust species collected from different host species, no qualitative differences were found in some cases (Puccinia coronata); in other cases the differences between samples were as large as between species (P. recondita, P. brachypodii). Because primary infection structures develop on virtually any graminaceous plant, all observations were done using barley or Triticum dicoccum seedlings as substrate. The results indicate that inclusion of mycelial morphology in description of rust taxa may be helpful in taxonomic studies. The differences in mycelial morphology may also be exploited in certain phytopathological studies.
Marine fungi from Seychelles. III. Aniptodera mangrovii sp.nov. from mangrove wood
Authors: Hyde Kevin D. , Farrant C. A. , Jones E. B. Gareth
Published: December 2009

Collections of higher marine fungi in Seychelles included an undescribed species of Aniptodera: A. mangrovii Hyde sp.nov. from driftwood and dead mangrove wood. This species differs from A. chesapeakensis in the size of the ascospores and in ascospore appendage morphology. Aniptodera mangrovii is described and illustrated by light microscope and scanning and transmission electron microscope micrographs.
Effects of CO2 enrichment and nutrition on growth, photosynthesis, and nutrient concentration of Alaskan tundra plant species
Authors: Oberbauer Steven F. , Sionit Nasser , Hastings Steven J. , Oechel Walter C.
Published: December 2009

Three Alaskan tundra species, Carex bigelowii Torr., Betula nana L., and Ledum palustre L., were grown in controlled-environment chambers at two nutrition levels with two concentrations of atmospheric CO2 to assess the interactive effects of these factors on growth, photosynthesis, and tissue nutrient content. Carbon dioxide concentrations were maintained at 350 and 675 μL L−1 under photosynthetic photon flux densities of 450 μmol m−2 s−1 and temperatures of 20:15 °C (light:dark). Nutrient treatments were obtained by watering daily with 1/60- or 1/8- strength Hoagland's solution. Leaf, root, and total biomass were strongly enhanced by nutrient enrichment regardless of the CO2 concentration. In contrast, enriched atmospheric CO2 did not significantly affect plant biomass and there was no interaction between nutrition and CO2 concentration during growth. Leaf photosynthesis was increased by better nutrition in two species but was unchanged by CO2 enrichment during growth in all three species. The effects of nutrient addition and CO2 enrichment on tissue nutrient concentrations were complex and differed among the three species. The data suggest that CO2 enrichment with or without nutrient limitation has little effect on the biomass production of these three tundra species.
Ectomycorrhizal fungi of Larix laricina and the interspecific and intraspecific variation in response to temperature
Authors: Samson Julie , Fortin J. A.
Published: December 2009

The ability of tamarack to form ectomycorrhizae with different fungi was investigated by using a pouch technique. Ninety-one out of 109 fungal isolates from 25 different species formed ectomycorrhizae on larch seedlings. Tamarack displays strong specificity for ectomycorrhizal fungi identified as sporocarp-specific to larch under field conditions: Suillus grevillei, S. cavipes. Fuscoboletinus aeruginascens, F. spectabilis, F. paluster, and F. grisellus. These fungal species induced more rapid and extensive ectomycorrhizal development in growth pouches than the other less specialized fungi. Radial growth rates on Petri dishes of isolates of these six bolete species were observed at 10, 15, 20, 25, and 30 °C, to study interspecific and intraspecific variation. The results demonstrated strong intraspecific variations and suggest a great genetic variability of the physiological activity within ectomycorrhizal species. Interspecific comparisons, however, revealed that some species possessed characteristic behaviours in response to temperature. As compared with a "high-temperature fungus," Pisolithus tinctorius, the bolete species showed distinct adaptations and tolerances to low and high temperatures. No consistent relationship was established between geographical origin of the fungal isolates and their growth rates. The results are discussed in relation to the selection of ectomycorrhizal fungi potentially used inoculum in forestry practice.
Ascocratera manglicola gen. et sp. nov. and key to the marine Loculoascomycetes on mangroves
Authors: Kohlmeyer Jan
Published: December 2009

The new genus Ascocratera (Melanommatales, Massariaceae?) with the single species A. manglicola is described from dead wood of mangrove trees (Avicennia germinans, Conocarpus erecta (?), Laguncularia racemosa, Rhizophora mangle) in the Atlantic and Pacific oceans. The new obligately marine species is one of the most common intertidal fungi. It has been collected 42 times on seven islands off the Belize coast and in Bermuda, Mexico, Tobago, and Australia (New South Wales). A key for all 16 marine Loculoascomycetes occurring on mangroves is given.
Studies of the development of wheat (Triticum aestivum) pollen: formation of the pollen aperture
Authors: El-Ghazaly Gamal , Jensen William
Published: December 2009

Pollen of Triticum aestivum is described at a series of developmental stages. Observations are recorded on the ultrastructural level and the light microscopy level. The pollen aperture starts to develop at the late tetrad period. The fibrillar coat of the plasma membrane is thinner at the site of the developed pore than in the rest of the wall. The bacules are developed as dense stained patches distributed in the fibrillar matrix. The tectum is formed as a result of deposition of material on the distal surface of the fibrillar matrix. On release of the microspores from the tetrad, development of the foot layer takes place on a trilamellated structure. Additional trilamellated structures are formed and are seemingly associated with the proximal surface of the foot layer in the nonaperture exine. These lamellations are the progenitors of a highly developed endexine in the annulus. At the early vacuolate stage a thick granular–fibrillar layer is developed under the operculum. This layer becomes highly compressed in the vacuolate pollen grain, which indicates that it may function as a cushion that protects the operculum from detaching by elimination of cytoplasmic pressure initiated during pollen vacuolation. Zwischenkörper is developed between the convoluted plasma membrane and the compact granular–fibrillar layer below the operculum. The intine is developed as a thin layer under Zwischenkörper and becomes very thick at the border between the annulus and the nonapertural wall.