Showing papers in "Botany in 1979"
TL;DR: A simple, rapid method requiring few manipulations for the extraction of chlorophylls from fragmented leaf tissue of angiosperms and gymnosperms is compared with the widely used acetone method, which makes use of incubation at 65 °C of leaf tissue immersed in dimethyl sulphoxide.
Abstract: A simple, rapid method requiring few manipulations for the extraction of chlorophylls from fragmented leaf tissue of angiosperms and gymnosperms is compared with the widely used acetone method. Unlike the acetone method where grinding and subsequent centrifugation are essential, this method makes use of incubation at 65 °C of leaf tissue immersed in dimethyl sulphoxide. The new method was found to be as efficient as acetone for chlorophyll extraction and superior in terms of chlorophyll stability.
2,810 citations
TL;DR: Two techniques were evaluated for detecting sexual and aposporous embryo sacs in an apomictic grass and yielded identical interpretations of embryo sac morphology.
Abstract: Two techniques were evaluated for detecting sexual and aposporous embryo sacs in an apomictic grass. Pistils of Cenchrus ciliaris L. were fixed in formalin – acetic acid – alcohol (FAA), cleared in...
228 citations
TL;DR: It was found that the majority of plants in undisturbed environments in this area of the Red Desert of Wyoming are mycorrhizal, and the predominance of plants belonging to the family Chenopodiaceae was of interest.
Abstract: Studies have been initiated on the occurrence of vesicular–arbuscular mycorrhiza (VAM) in plant communities of revegetated mine spoils and undisturbed areas of the Red Desert of Wyoming. It was found that the majority of plants in undisturbed environments in this area are mycorrhizal. On disturbed sites, no mycorrhiza were encountered. Of interest for both the undisturbed and disturbed communities was the predominance of plants belonging to the family Chenopodiaceae. The major difference between the plant species encountered in each community is associated with their reproductive strategy, as well as whether the plants possessed VAM. The major species encountered on undisturbed sites are Atriplex gardneri, At. confertifolia, Ceratoides lanata, Grayia spinosa, Kochia americana, and Sarcobatus vermiculatus, all possessing mycorrhiza. Halogeton glomeratus predominated in disturbed sites and did not possess VAM. The role of VAM in both succession and reproductive strategies of plants is also discussed.
167 citations
TL;DR: Periodicity, location, extent, and severity of fires from 1665 to 1975 were determined for a 43 200-ha area of Jasper National Park using fire-scar dendrochronology to determine age, size, density, crown height, and temporal frequency of forest patches.
Abstract: Periodicity, location, extent, and severity of fires from 1665 to 1975 were determined for a 43 200-ha area of Jasper National Park using fire-scar dendrochronology. Before fire suppression began i...
165 citations
TL;DR: Only 4 of the 28 fungi tested formed characteristic ectomycorrhizae: Alpova diplophloeus, Paxillus involutus, Aslraeus pteridis, and Scleroderma hypogaeum forming alder mycorrhiza formation with red alder.
Abstract: Cultures of 28 ectomycorrhizal fungi were tested in pure culture syntheses for mycorrhiza formation with red alder. Only 4 of the 28 fungi tested formed characteristic ectomycorrhizae: Alpova diplophloeus, Paxillus involutus, Aslraeus pteridis, and Scleroderma hypogaeum. These mycorrhizae are briefly described, and the specialization of alder mycorrhizae is discussed.
143 citations
TL;DR: The development of preemergent and early emergent stages of soybean and garden pea root nodules has been studied utilizing the superior preservation and resolution obtained by noncoagulative fixatives and subsequent embedding in plastic.
Abstract: The development of preemergent and early emergent stages of soybean (Glycine max) and garden pea (Pisum sativum) root nodules has been studied utilizing the superior preservation and resolution obt...
136 citations
TL;DR: Folin-type resins used to purify plant extracts ofbasic amino acids that interfere with proline determination are not selective and partially retain this amino acid and the basic amino acids, so their use should be avoided.
Abstract: Folin-type resins used to purify plant extracts of basic amino acids that interfere with proline determination are not selective and partially retain this amino acid and the basic amino acids. Ther...
124 citations
TL;DR: The salt marshes at La Perouse Bay, Manitoba, are described and the role of geese in producing these pond...
Abstract: The salt marshes at La Perouse Bay, Manitoba, are described. Unconsolidated, water-saturated sediment is colonized by Hippuris tetraphylla, Puccinellia phryganodes, and Carex subspathacea. These sediments undergo frost heave, and on elevated mounds, Elymus arenarius var. mollis and Salix brachycarpa become established. This last species is the dominant one of the low willow tundra, which is the characteristic vegetation of the coastal strip. Where drainage is impeded in the upper marsh, relatively high salinities occur and species such as Salicornia europaea agg. and Triglochin maritima are present.A population of 10 000 to 20 000 lesser snow geese (Anser caerulescens) feed, in summer, on Puccinellia phryganodes, Carex subspathacea, Potentilla egedii, and Elymus arenarius var. mollis. The birds strip the shallow turf of Puccinellia in low lying areas between clumps of willow. This terracing of the surface creates depressions which become filled with water and ice. The role of geese in producing these pond...
120 citations
TL;DR: It is discussed the possibility that honey bees may provide major 'new' selection pressures on floral display, nectar production patterns, and flowering phen...
Abstract: Spatial and temporal variation in insect visitation rates are analyzed with respect to nectar production and inflorescence size of Asclepias syriaca L., the common milkweed. Nectar sugar production...
112 citations
TL;DR: Throughout functional megaspore and two-nucleate megagametophyte, ribosome concentrations, organelle numbers, and structural complexity increase, and the transition from vegetative to reproductive gametophytic growth presumably follows this biosynthetic period.
Abstract: Polygonum-type embryo sac development was examined in Zea mays with light, fluorescence, and electron microscopy. Megasporocyte polarity is expressed in organelle distribution, aniline blue wall fluorescence, and chalazal location of plasmodesmata. In the meiotic cytoplasm concurrent with the sporophyte–gametophyte transition, ribosome concentrations are low, and membrane-bound organelles are simplified. The functional megaspore is the largest and most chalazal cell of the resultant triad or tetrad. Aniline blue fluorescence is intense in nonfunctional megaspore walls, whereas in the functional megaspore intensity decreases from the chalazal end to that in nucellar walls. Throughout functional megaspore and two-nucleate megagametophyte, ribosome concentrations, organelle numbers, and structural complexity increase. The transition from vegetative to reproductive gametophytic growth presumably follows this biosynthetic period. In the four-nucleate stage, a second phase of mitochondrial simplification coinci...
109 citations
TL;DR: Papillae were deposited in barley epidermal cells directly beneath appressoria of Erysiphe graminis f.
Abstract: Papillae were deposited in barley epidermal cells directly beneath appressoria of Erysiphe graminis f. sp. hordei and appeared as hemispherical, internal wall appositions. The papilla response began shortly after the formation of a rapidly moving cytoplasmic aggregate beneath the appressorium. As documented in coleoptile tissue by time-lapse light microcinematography, the papillae grew rapidly for 20–30 min after becoming visible, their radii increasing by 0.1 μm/min. For small papillae, deposition continued for about 30 min; for larger papillae, deposition continued for 120–180 min. Results with transmission electron microscopy on leaf epidermal cells suggested that papilla deposition by host cytoplasmic aggregates can be divided into four sequential stages: (i) the deposition of osmiophilic (lipidic) materials, (ii) the deposition and partial compaction of nonosmiophilic, amorphous material (probably insoluble polysaccharides), (iii) compaction of nonosmiophilic, amorphous material, and (iv) the incorpo...
TL;DR: The degradation by Phanerochaete chrysosporium of "natural" lign in aspen wood, like synthetic lignin, was inhibited by nitrogen and stimulated by carbohydrate, and the carbon:nitrogen ratio of the medium was a better predictor of lignIn degradation than the absolute carbohydrate and nitrogen levels.
Abstract: The degradation by Phanerochaete chrysosporium of "natural" lignin in aspen wood, like synthetic lignin, was inhibited by nitrogen and stimulated by carbohydrate. Nitrogen delayed the appearance and reduced the level of ligninolytic activity and indirectly hastened its decline by accelerating depletion of the carbohydrate supply. The carbon:nitrogen ratio of the medium was a better predictor of lignin degradation than the absolute carbohydrate and nitrogen levels. Unlike nitrogen limitation, sulphate and phosphate limitation of growth did not stimulate lignin metabolism.
TL;DR: The Weibull distribution is shown to fit well with empirical data of fire intervals for a population of sites, and the relationship of the distribution's hazard of burning function to vegetation composition and r–K selection is discussed.
Abstract: The Weibull distribution is shown to fit well with empirical data of fire intervals for a population of sites. The distribution demonstrates that the recurrence of fire in the subarctic forests of the Northwest Territories, Canada, is predictable. The three parameters of the distribution describe in ecological terms the lag before reburning can occur, the expected recurrence time of fire, and the shape of the variation around the expected recurrence. The parameters behave consistently with logically independent empirical evidence related to the regional and local climate and topography. The relationship of the distribution's hazard of burning function to vegetation composition and r–K selection is discussed.
TL;DR: The modification of the genotype of the Cadet and Rescue cultivars of spring wheat by disomic chromosome substitution altered the amount of plant nitrogen derived from dinitrogen fixation by the associated bacterium in a phytotron experiment.
Abstract: The modification of the genotype of the Cadet and Rescue cultivars of spring wheat (Triticum aestivum L. emend. Thell) by disomic chromosome substitution altered the amount of plant nitrogen derived from dinitrogen fixation by the associated bacterium in a phytotron experiment. With the exception of the C-R5B line, inoculation of the parent Cadet or its substitution lines with either the bacillus C-11-25 or Azospirillum brasilense increased plant dry matter and the total N yield. Rescue lines were unaffected by inoculation unless genotypically altered by substitution of the 5B or 5D chromosome from Cadet. Different substitution lines reacted uniquely to inoculation with the specific bacteria: C-R2A and R-C2D promoted greater dinitrogen fixation by A. brasilense; C-R5D, R-C5B, and R-C5D promoted greater dinitrogen fixation by the C-11-25 bacillus. Both bacteria had high and identical levels of dinitrogen fixation in association with the C-R2D line; neither bacterium fixed N when grown in association with t...
TL;DR: An indication of the metabolic capacity of the plastids was determined by monitoring the ribulose-1,5-bisphosphate carboxylase activity in the endosperm.
Abstract: During castor oil seed development, changes occur in the activities of enzymes involved in fatty acid biosynthesis, glycolysis, and the pentose phosphate pathways. The activities of acetyl-CoA carboxylase, phosphofructokinase, pyruvate kinase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase per seed increase during the phase of rapid oil synthesis in the endosperm. As the seed matures and the rate of fatty acid synthesis decreases, there is a corresponding diminution in the activities of these enzymes. An indication of the metabolic capacity of the plastids was determined by monitoring the ribulose-1,5-bisphosphate carboxylase activity in the endosperm.
TL;DR: Six ectomycorrhizal fungi commonly associated with Douglas-fir were tested in vitro for acid phosphatase activity by measuring the amount of p-nitrophenyl phosphate converted to p-Nitrophenol and by examining their production of isoenzymes detectable by starch gel electrophoresis.
Abstract: Six ectomycorrhizal fungi commonly associated with Douglas-fir were tested in vitro for acid phosphatase activity by measuring the amount of p-nitrophenyl phosphate converted to p-nitrophenol and by examining their production of isoenzymes detectable by starch gel electrophoresis. Both test methods showed acid phosphatase activity to be highest in Hebeloma crustuliniforme, followed by progressively lower activity in Laccaria laccata, Amanita muscaria, and Thelephora terrestris. Rhizopogon vinicolor and Piloderma bicolor showed low activity. We discuss the significance of these fungi in the utilization of complex phosphates by tree roots.
TL;DR: Geosmithia Pitt is erected to accommodate species, previously placed in Penicillium, with the following combination of characters: colonies with conidia in colors other than grey–blue or grey–green, penicilli with all elements roughened, and with both phialides and conidia cylindroidal.
Abstract: Geosmithia Pitt is erected to accommodate species, previously placed in Penicillium, with the following combination of characters: colonies with conidia in colors other than grey–blue or grey–green...
TL;DR: A quantitative analysis of the habitats of 14 species of Sphagnum found in the Caribou Mountains of northern Alberta and a literature review are the basis for a discussion of the landscapes of these species as they occur in circumboreal–subarctic regions.
Abstract: A quantitative analysis of the habitats of 14 species of Sphagnum found in the Caribou Mountains of northern Alberta and a literature review are the basis for a discussion of the habitats of these species as they occur in circumboreal–subarctic regions. Despite the implication inherent in the name, the Caribou Mountains are not mountains; the formation is an extensive, elevated plateau, which is underlain by more-or-less continuous permafrost. Three habitat types predominated in our study area: an upland "treed-tundra" (which is dominant over much of the plateau) with scattered Picea mariana and a hummocky bottom layer of sphagna; rounded "thaw-pocket" depressions dominated by carpets of Sphagnum and some carices; and streams defined by a dense zone of shrubs with the narrow water channel bordered by more-or-less firm lawns of Sphagnum species. Three gradients, which are considered to have a predominant influence on the occurrence of Sphagnum species, are wet to dry, ombrotrophic to minerotrophic, and sha...
TL;DR: It was determined that the active arbuscule was the most probable site of breakdown of phosphorus granules and general morphological appearance and location were not adequate criteria for the identific...
Abstract: The vesicular–arbuscular mycorrhizal fungus Glomus mosseae was examined by transmission electron microscopy and energy dispersive X-ray analysis. Electron-dense granules, found within vacuoles, were analyzed by X-ray analysis and found to contain high concentrations of phosphorus and calcium. These granules were similar in appearance to the polyphosphate granules described in other organisms. Highly vacuolated intercellular hyphae and vesicles possessed the greatest number of phosphorus granules. The granules were present in vacuolated arbuscular hyphae but absent from completely collapsed arbuscules. It was determined that the active arbuscule was the most probable site of breakdown of phosphorus granules. There were two other types of cellular inclusions, one vacuolar and one cytoplasmic, that could not be identified by X-ray analysis but that could easily be mistaken for phosphorus granules. It was concluded that general morphological appearance and location were not adequate criteria for the identific...
TL;DR: Two phases of early vegetative growth were identified by their different responses to combined nitrogen, primarily through an increased partitioning of assimilates to shoot development and a period of nitrogen stress which lasted only until the 3rd week.
Abstract: Pea plants (Pisum sativum L. cv. Trapper) were inoculated and grown in controlled-environment chambers at two irradiance levels. Shoot and root dry weights and nitrogen contents, total leaf and sti...
TL;DR: The enhanced macerating activity of Pectolyase Y23 was found to be due not only to the high activity of pectin lyase and polygalacturonase, but also to a factor which stimulated maceration.
Abstract: Pectolyase Y23, a new maceration enzyme from Aspergillus japonicus, combined with Cellulase Onozuka R10 liberated protoplasts from tobacco mesophyll in less than 25 min. The protoplasts divided to ...
TL;DR: The ontogeny of the mycorrhizal association of a Glomus species in bean roots was studied and electron-dense particles adjacent to external hyphae bind iron were found to be phenolic in nature.
Abstract: The ontogeny of the mycorrhizal association of a Glomus species in bean roots was studied. Electron-dense particles adjacent to external hyphae bind iron, as shown by X-ray microprobe analysis, whe...
TL;DR: Structural specializations occur in the suspensor at the proembryo stage with the formation of wall ingrowths and a change in the configuration of the smooth endospermic reticulum is also observed.
Abstract: Structural specializations occur in the suspensor at the proembryo stage with the formation of wall ingrowths. Soon after the appearance of the ingrowths, mitochondria, plastids, polysomes, and smooth endoplasmic reticulum greatly increase in their abundance within the suspensor cells. By the late globular stage, wall ingrowths are extremely well developed and the cells within the suspensor are packed with cellular organelles. The nucleus of the suspensor cell at the heart stage also takes on an active appearance. The nucleus becomes highly lobed in shape and micronucleoli can also be found. There is little change in the overall ultrastructural pattern of the cell till the cotyledon stage. At this stage, wall thickening occurs in all suspensor cells and the outlines of most of the ingrowths become less obvious. The mitochondria, plastids, and polysomes become less abundant and a change in the configuration of the smooth endospermic reticulum is also observed. The ontogenetic changes of the cellular organe...
TL;DR: The aqueous extract of air-dried roots of Boerhaavia diffusa shows broad-spectrum antiviral activity and no phytoxic effects.
Abstract: The aqueous extract of air-dried roots of Boerhaavia diffusa shows broad-spectrum antiviral activity and no phytoxic effects Infection by four viruses was completely prevented, at treated and nont
TL;DR: Soils collected from seven sample plots in a burned mixed-wood area in northern Saskatchewan were held at optimum laboratory conditions to determine the number of viable seeds and latent underground buds and a total of 270 plants developed.
Abstract: Soils collected from seven sample plots in a burned mixed-wood area in northern Saskatchewan were held at optimum laboratory conditions to determine the number of viable seeds and latent underground buds. A total of 270 plants developed, representing a rate of emergence of 426 plants/m2 of which 372 plants (87%) originated from seed and 54 (13%) came from remnant roots or rhizomes. In addition, 19 birch seeds were extracted from the soil following the germination tests giving a total count of 456 propagules/m2. Tree species accounted for 42.9% of this total.
TL;DR: Glandular trichomes on the inflorescence of Chrysanthemum morifolium cv.
Abstract: Glandular trichomes on the inflorescence of Chrysanthemum morifolium cv. Dramatic are initiated from a single epidermal cell outgrowth and develop through an anticlinal division and a series of periclinal divisions to form a biseriate multicellular structure. Cells of the young trichome contain a large nucleus with prominent nucleoli and few small cellular organelles. Prior to the secretory stage, numerous ribosomes, polyribosomes, and dictyosomes are present in a dense cytoplasm but most of the dictyosomes are lost as secretion commences. Plastids in the stalk cells senesce but in a different manner than those in the upper tiers of secretory cells. Lipoidal substances form in the degenerating plastids. Cell wall ingrowths and the deposition of a flocculent material in the primary cell wall characterize secretory hairs. In very old hairs cellular lysis takes place with mitochondria being the last cellular organelle to remain intact. The secreted material, which collects in a subcuticular space, appears to...
TL;DR: The interactions between soybean plants and two species of mycorrhizal fungi were examined and the number of infection units in young seedlings was found to increase in the presence of increasing quantities of Glomus fasciculatus inoculum, until a maximum was reached.
Abstract: The interactions between soybean plants and two species of mycorrhizal fungi were examined. The number of infection units in young seedlings was found to increase in the presence of increasing quan...
TL;DR: Fumigations caused significant reduction in total nonstructural carbohydrate and protein contents of actively growing seedlings within 24 h after fumigation, however, carbohydrate andprotein contents of new of activelygrowing seedlings persisted throughout the 5-week period.
Abstract: The effects of SO2 (2 ppm for 6 h), O3 (0.9 ppm for 5 h), and SO2–O3 mixtures (2 ppm SO2 and 0.9 ppm O3 for 5 h followed by SO2 for 1 h) were studied on metabolite contents of 4-month-old, actively growing and quiescent Ulmus americana L. seedlings. Effects on metabolite contents in leaves, stems, and roots were examined 24 h, 1 week, and 5 weeks after exposure to pollutants for actively growing seedlings, and 24 h and 1 week for quiescent seedlings. Fumigations caused significant reduction in total nonstructural carbohydrate and protein contents of actively growing seedlings within 24 h after fumigation. By the end of 5 weeks, however, carbohydrate and protein contents of new ( 1 cm long) of actively growing seedlings persisted throughout the 5-week period. Changes in lipid contents o...
TL;DR: The population arising latest in the season had the lowest percentage emergence but the greatest percentage survival of emerged plants to the time of flowering, and these populations also had the best reproductive performance.
Abstract: Populations of the colonizing weeds Rumex crispus L. and R. obtusifolius L. were initiated from seed following disturbance on three occasions between May and September 1976. Three distinct cohorts were followed within each population. Cohorts which had the same order of emergence within a population but different dates of emergence had similar mortality rates. On the other hand, when cohorts of different emergence order and similar emergence dates were compared, those cohorts which emerged first had the lower mortality rates. For both species, the population arising latest in the season had the lowest percentage emergence but the greatest percentage survival of emerged plants to the time of flowering. These populations also had the best reproductive performance. The latest emerging population of R. crispus was the only one to produce as many seeds as had originally been sown, despite the fact that less than 10% of the emerged seedlings survived the winter and less than 1% of the seed pool gave rise to flo...
TL;DR: An antiviral agent, active against spherical and tubular viruses in hypersensitive and systemic hosts, has been isolated from the roots of Boerhaavia diffusa and preliminary analysis indicates that the inhibitor may be a glycoprotein with a molecular weight of 16’000–20 000 daltons.
Abstract: An antiviral agent, active against spherical and tubular viruses in hypersensitive and systemic hosts, has been isolated from the roots of Boerhaavia diffusa. Partial purification of inhibitor by organic solvents, Sephadex gel, and protein precipitants has been achieved. Preliminary analysis indicates that the inhibitor may be a glycoprotein with a molecular weight of 16 000–20 000 daltons.