bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro growth of wheat and flax rust fungi on complex and chemically defined media
Authors: Bose A. , Shaw Michael
Published: September 2008

Growth from uredospores seeded in axenic culture is described for several races of Puccinia graminis Pers. f. sp. tritici (Erikss. and Henn.) and race 3 of Melampsora lini (Ehrenb.) Lév. on complex media containing peptone, yeast extract, and bovine serum albumin (BSA); and for an Australian isolate of Puccinia graminis, race 126-ANZ 6,7, and Melampsora lini, race 3, on chemically defined, liquid media.Of six North American isolates of Puccinia graminis only race 38 formed colonies approaching those of race 126-ANZ 6,7 in final size and general morphology on complex media. 5′AMP had no effect on the growth of 126-ANZ 6,7, but cyclic AMP inhibited growth after uredospore germination. Good growth and sporulation were obtained with 126-ANZ 6,7, but not with the other isolates tested, using a new, chemically defined liquid medium, sterilized by millipore filtration, and containing glucose, Czapek's minerals plus micronutrients, Ca2+, glucose and aspartic acid, glutathione, and cysteine. Uredospores produced in culture reinfected exposed mesophyll tissue, but not intact seedling leaves of wheat.Highly reproducible growth and sporulation of Melampsora lini, race 3, were obtained routinely on a solid medium containing Difco-Bacto agar, sucrose, Knop's minerals, micronutrients, yeast extract, peptone, and BSA. Vegetative cultures, capable of reinfecting the cut ends of surface-sterilized flax cotyledons, could be maintained indefinitely by subdivision before sporulation and transfer to the same medium minus BSA. Evidence is presented that BSA stimulated the development of colonies and the formation of uredospores. The mode of action of BSA is unknown, but it could not be replaced by putrescine.A new chemically defined, liquid medium containing sucrose, Knop's mineral salts, micronutrients, aspartic (or glutamic) acid, and cysteine supported the growth of colonies of Melampsora lini in a highly reproducible manner. The formation of uredospores and teliospores by these colonies was controlled by (a) the level of Ca2+ (as Ca(NO3)2∙4H2O), (b) the concentration of aspartic acid, and (c) the number of colonies per flask. At inoculum levels giving 40 to 60 colonies per flask, in media containing 8.5 mM Ca+ and 45 mM aspartic acid, uredospore formation occurred in 60 to 70% of the colonies. A decrease in the Ca2+ level to 4.25 mM, or a decrease in aspartic acid to 22.5 mM, or adjustment of the inoculum level to give about 10 colonies per flask each resulted in only infrequent sporulation. The uredospores produced in vitro infected intact, 1-week-old flax cotyledons in a normal manner.
Ultrastructure of the zoospores of Entophlyctis confervae-glomeratae, Rhizophydium patellarium and Catenaria anguillulae
Authors: Chong James , Barr D. J. S.
Published: September 2008

The fine structure of zoospores of Entophlyctis confervae-glomeratae, Rhizophydium patellarium, and Catenaria anguillulae has been described and compared. The zoospores of E. confervae-glomeratae contain many posteriorly located mitochondria in a petal-like arrangement. On the inner (proximal) side of a kinetosome are two electron-dense, slightly curved bands with the convex side directed inward towards the eccentrically located nucleus. Microtubules radiate from the convex side of the bands. Two or three lipid bodies are seen usually in the anterior region of the zoospore with microbodies often associated with them. Ribosomes are scattered throughout the cytoplasm. The zoospores of R. patellarium contain a single, bowl-shaped mitochondrion in the posterior region and a centrally located nucleus. Ribosomes are mainly clustered between the mitochondrion and the nucleus and are partially enclosed by a double-membrane envelope. No microtubules are seen associating with the kinetosome and the non-functional centriole lies parallel to the kinetosome. In the anterior region there is a single lipid body as well as two types of microbodies: very electron-dense microbodies un-associated with any other organelle, and a finely granular microbody associated closely with the lipid body. The zoospores of C. anguillulae contain a single basal mitochondrion with the associated side-body complex. From the proximal region of the kinetosome, a set of 27 microtubules radiate anteriorly and surround the base of the cone-shaped nucleus. Ribosomes are enclosed within a distinct nuclear cap. Gamma bodies are present in the cytoplasm. Taxonomic implications resulting from this study are discussed.
Pythium polymastum pathogenic on oilseed rape and other crucifers
Authors: Vanterpool T. C.
Published: September 2008

Pythium polymastum has been found in the roots of oilseed rape (Brassica campestris and B. napus), Capsella bursa-pastoris, and Lunaria annua, grown in field soil from widely separated localities in Saskatchewan. It is virulent on rape and 18 other crucifers, and avirulent or only slightly virulent on numerous cultivated plants belonging to other families. This is the first report of the fungus as a pathogen on crucifers. It is suggested that it may play a part in a root-rot complex, that it is indigenous, and that cruciferous weeds act as alternative hosts.
A quantitative investigation of symplasmic transport in Chara corallina. I. Ultrastructure of the nodal complex cell walls
Authors: Fischer R. A. , Dainty J. , Tyree M. T.
Published: September 2008

We present a quantitative ultrastructural study of the size and frequency (density distribution) of plasmodesmata in the cell wall in common between the internodal cell and peripheral cell (and central cell) of Chara corallina. In the wall in common between the central cell and internodal cell the relative area occupied by plasmodesmata is 15.3%; the pore diameter (less the plasmalemma) is 118 nm; the length is 1.54 μm, and the frequency is 1.4 × 109 pores/cm2. In the wall in common between the peripheral cell and internodal cell the relative area occupied by the plasmodesmata is 9.6%; the pore diameter is 100 nm; the length is 1.07 μm; and the frequency is 1.2 × 109 pores/cm2. The plasmodesmata have an anastomosing structure like Nitella translucens but the pore diameter and frequency are much greater.
Scanning electron microscopy of the callose wall and intermeiocyte connections in angiosperms
Authors: Whelan Ernest D. P. , Haggis G. H. , Ford E. J.
Published: September 2008

Scanning electron microscope studies of anthers of the dicotyledons Helianthus annuus, Solanum tuberosum, and Lupinus polyphyllus, and the monocotyledons Iris pseudo-acoris and a Lilium hybrid revealed discontinuities or holes in the meiocyte callose wall and continuity of the plasma membranes of adjacent meiocytes. The holes in the callose wall generally were confined to areas where neighboring meiocytes were in contact. The holes varied in size within locations and between taxa. The largest holes, about 2.4 μm diameter, were found in Lupinus. Fixation in standard acid–alcohol fixatives resulted in marked plasmolysis and loss of cytoplasmic detail, but the nucleolus and bivalents were readily apparent. Fixation in buffered glutaraldehyde, with or without postfixation in OSU4, preserved the cytoplasmic organelles and plasmolysis was minimal, but bivalents could not be distinguished. All fixatives preserved the nuclear membrane so that the nuclear region was clearly delimited from the cytoplasm.
Macrochemical reactions of species of Boletus and Tylopilus
Authors: Grund D. W. , Harrison K. A.
Published: September 2008

Macrochemical reactions are reported on 19 species of Boletus and 7 species of Tylopilus by using a spot-plate method of testing. Six species of Boletus are new records for Nova Scotia and three of these are new for Canada. Two species of Tylopilus are new provincial records, of which one is new for Canada. Tylopilus gracilis, which Singer places in the genus Porphyrellus, gave a pattern reaction similar to that of T. felleus, indicating that the two are closely related. Tylopilus pseudoscaber had a pattern of reactions that was quite different from any other Boletus or Tylopilus species tested. A striking yellowish-orange reaction to aniline, not found in other species, occurred in B. ornatipes. A distinctive dark ring occurred around the spot where ammonia had been applied to the cutis of B. separans.not available
The effects of gibberellin A3, photoperiod, and age on vegetative growth and flowering in Cosmos bipinnatus var. Sensation
Authors: Molder Marje , Owens John N.
Published: September 2008

Plants of Cosmos bipinnatus Cav. 'Sensation' (a quantitative short-day plant) were grown continuously under conditions favorable or unfavorable for flowering, and some plants in each group were treated with gibberellic acid (GA3). Morphological and anatomical observations revealed that GA3 promoted floral initiation under non-inductive long days but not as efficiently as inductive short days, as judged by the rate of apical transition to the reproductive state. GA3 did not influence the total number of plants that flowered but did increase height growth. Plants treated with GA3 had a normal percentage of initiation, but a much lower developmental rate. Macroscopic recognition of flowering was not possible until the inflorescence stage of the apex.Floral apices of Cosmos are formed by the transition of previously vegetative apices, the apex passing into an intermediate stage typical of most plants held under non-inductive conditions. Transitional, prefloral, and inflorescence stages follow. The formation of an intermediate stage may account for many of the conflicting results observed in physiological studies since there is a great variation in response rate depending on age of plant and stage of the apex at the start of the experiment. Anatomical observations support the findings that although GA3 promotes floral initiation in Cosmos when applied under non-inductive conditions, floral development may not continue, thus resulting in an apparent lack of response. This may also be true of many other plants considered "non-responsive" to GA3 under non-inductive conditions.
Sucrose and water uptake from concentrated sucrose solutions by gladiolus shoots and the effect of these treatments on floret life
Authors: Bravdo B. , Mayak S. , Gravrieli Y.
Published: September 2008

Detached flowering gladiolus shoots (Gladiolus grandiflora cv. Oscar) were subjected to sucrose solutions with concentrations up to 50% sucrose. Sucrose was found to be absorbed at all concentrations. The amount of solution absorbed decreased when the concentration of the solution was increased, while the amount of sucrose absorbed increased up to 4.2 g sucrose per spike per 24 hours in 40% sucrose. Increasing the concentration beyond 40% resulted in the same amount of sucrose uptake while the rate of solution uptake was decreased. Continuous treatment of the shoots with sucrose resulted in continuous sucrose uptake at all concentrations, but transferring the shoots to tap water caused an increased uptake of water which was dependent on the amount of sucrose previously absorbed. Sucrose was also absorbed by leaves although at lower rates since it induced stomatal closure. The florets were found to be the most active organs for sucrose accumulation and the subsequent water uptake. Sucrose pretreated florets were found to last longer with their maximal weight achieved 2 days later than control. The maximum gain in weight in the treated shoots was 80% compared to 15% in the water control.
A new species of Salix from northern British Columbia
Authors: Argus George W.
Published: September 2008

A new boreal forest species, Salix raupii, is described from northern British Columbia. It is related to Salix glauca, from which it differs in its glabrous leaves and branchlets, glabrous pistils and bracts, red stigmas, and unbranched styles.
The evolution of a pathogenic strain of tobacco mosaic virus in tomato: a host-passage phenomenon
Authors: MacNeill B. H. , Boxall Mary
Published: September 2008

When an isolate of tobacco mosaic virus (TMV) strain 0, uniquely labelled with a genetic marker governing symptom expression, was used to infect the susceptible component of an intergrafted pair of susceptible (Tm-0/Tm-0) and resistant (Tm-2/+) tomato plants, the virus moved through the graft union and established a systemic infection in the Tm-2/+ component. Subsequently, a new virus identified as TMV strain 2 was detected in the resistant plant. Since the new virus also possessed the genetic marker which characterized the original inoculum, it is inferred that the new strain did not preexist but was derived from the parent virus during host passage.
Ribonucleic acids of differentiating and non-differentiating uredosporelings of wheat stem rust
Authors: Kim W. K. , Rohringer R.
Published: September 2008

Uredospores of wheat stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn.) were deposited onto Millipore membranes and allowed to germinate. Those remaining continuously at 20° formed germ tubes only (non-differentiated), but those exposed to 30° for 90 min after the first 2 h of germination developed infection structures corresponding to appressoria and substomatal vesicles (differentiated).Nucleic acids were extracted with a phenol method from resting uredospores and from differentiated and non-differentiated sporelings. The amount of extractable RNA decreased as germination progressed, but no RNA was detected in the germination medium. The decrease in extractable RNA (up to 40%) occurred in both differentiated and non-differentiated sporelings.Acrylamide gel electrophoresis was used to separate RNA species and to determine their approximate molecular weights (in daltons): sporelings contained 25-S (1.65 × 106) and 18-S (0.80 × 106) ribosomal RNA (rRNA), 5-S (3.6 × 104) rRNA, and 4.5-S (2.4 × 104) transfer RNA (tRNA). Radioactive uridine, fed to sporelings, was incorporated mostly into 5-S rRNA and (or) tRNA.Acrylamide gel electrophoresis and sucrose density gradient centrifugation revealed that differentiated sporelings contained a type of RNA that was not detected in non-differentiated sporelings. It was heterogeneous and migrated in the 16-S to 5-S interval on polyacrylamide gels. Some of the RNA present in this fraction may have been preformed in resting spores and released from more complex material during the process of differentiation.
A quantitative investigation of symplasmic transport in Chara corallina. II. The symplasmic transport of chloride
Authors: Tyree M. T. , Fischer R. A. , Dainty J.
Published: September 2008

We report measurements of the tempo of 36Cl transport across the nodal complex of Chara corallina. By combining these data with the results of a quantitative ultrastructural study of the size and frequency of plasmodesmata in the nodal complex, we can calculate the resistance offered to diffusion by the plasmodesmata, assuming that diffusion is the rate-limiting step. Based on this assumption, the plasmodesmatal fluid is about 31 times more resistant to diffusion than water; but it is suggested that cyclosis in the internodal cells up to the nodal complex may have some rate-controlling influence. Also the viscosity of flowing cytoplasm can increase the resistance to diffusion above that in water. Therefore it is possible that the plasmodesmata are filled only with viscous or gelled cytoplasm.
The radial distribution and metabolism of IAA-14C in Pinus echinata stems in relation to wood formation
Authors: Nix Lawrence E. , Wodzicki Tomasz J.
Published: September 2008

Radial distribution of auxin in differentiating xylem tissues was studied in decapitated 8- to 14-year-old Pinus echinata stems to which indoleacetic acid (IAA-14C) in lanolin paste was applied during early and late growing season. Small segments of the treated stems were sectioned tangentially with a sliding microtome, the serial sections were collected, and the radioactivity of each section was measured. The results indicate that IAA is radially distributed in the differentiating tissues along a steep gradient from the cambial region to the differentiating xylem and that this distribution varies during the growing season in relation to the seasonal transition to latewood formation in intact trees.Forty-five to 60% of the radioactivity recovered in methanolic extracts of the differentiating xylem after a 2-day labeling period was in the form of IAA. After 7 days 10–15% of the radioactivity recovered was in the form of IAA. The radioactivity recovered separated into ether and aqueous fractions when the methanol extract was reduced, acidified, and partitioned with ether. Chromatography of aliquots of both fractions in several solvent systems revealed no individually significant metabolite of IAA. The aqueous fraction derivatives accumulated in the tissue, and later in the season the metabolism of IAA and the accumulation of the aqueous fraction apparently decreased. In experiments where excised differentiating xylem was incubated with a liquid medium containing IAA-14C, the conversion of radioactivity to the aqueous fraction was twofold greater in early season than in late season. The significance of the results is discussed with possible relation to the control of the seasonal transition to latewood formation in conifers.
The fine structure of the coffee leaf rust, Hemileia vastatrix
Authors: Rijo Luisete , Sargent J. A.
Published: September 2008

The fine structure of two races of Hemileia vastatrix that cause leaf rust in Coffea arabica is similar in many respects to earlier descriptions of other rust fungi. Certain features, however, are distinctive. Both hyphae and haustoria contain occasional tubular complexes composed of tubules about 300 Å in diameter. These might function as a Golgi apparatus. The haustorium neck ring incorporates the entire wall thickness at its proximal end, but distally only the outer and innermost layers of the wall are involved. The invaginated host plasmalemma, which surrounds the body of the haustorium, has a furrowed surface and in the adjacent haustorial sheath fibrillar elements are prominent. The plasmalemma furrows and the sheath fibrillar elements are discussed in relation to the organization of the structure of the sheath and absorption of materials through it.
Enzymological aspects of de novo synthesis of fructooligosaccharides in leaf disks of certain Asteraceae. IV. The activity of sucrose–sucrose 1-fructosyltransferase
Authors: Chandorkar K. R. , Collins F. W.
Published: September 2008

Sucrose–sucrose fructosyltransferase capable of synthesizing the trisaccharide 1F-fructosylsucrose from sucrose was partially purified from crude protein extracts of (1) lettuce leaf disks, which were incubated on a sucrose medium for 72 h, and (2) lettuce leaf midvein–petiole tissue, which normally contains fructosans ranging in degree of polymerization from 3 to about 10–11. Maximum transferase activity was associated with the protein exhibiting an apparent molecular weight of about 100 000 as estimated by gel filtration technique. The transferase was not detected in protein extract of unincubated leaf blade tissue. Evidence presented strongly suggests that the transferase was synthesized de novo in response to incubation of leaf disks on sucrose medium.
Mountain Park: a plant refugium in the Canadian Rocky Mountains
Authors: Packer John G. , Vitt Dale H.
Published: September 2008

It is suggested that the area in the vicinity of Mountain Park, Alberta, (52°50′ N; 117°20′ W) in the Canadian Rocky Mountains was a refugium during the Wisconsin period, where alpine and montane bryophytes and flowering plants survived the glaciation in situ. Evidence for this view includes data derived from geological investigations and from the present distribution of a number of bryophyte and angiosperm species. Alternative explanations to account for these distributions are discussed and reasons for rejecting them as highly improbable are presented.
Dependence of the level of nitrogenase activity on the water content of the thallus in Peltigera canina, P. evansiana, P. polydactyla, and P. pvaetextata
Authors: Kershaw K. A.
Published: September 2008

The rates of nitrogen fixation and the response to changing levels of thallus moisture have been monitored in Peltigera canina (L.) Willd., P. evansiana Gyel., P. polydactyla (Neck.) Hoffm., and P. praetextata (Somm.) Vain., using standard vapor-phase chromatography. Maximum levels of fixation range from 2.96 nmol of ethylene evolved/h mg dry weight in P. evansiana to 1.31 nmol C2H4/h mg dry weight in P. polydactyla. Each species shows a slightly different pattern of fixation response to changing levels of thallus moisture, and the pattern of fixation correlates with the ecological preferences of each species.
Plantlet formation from Lycopersicon esculentum leaf callus
Authors: Padmanabhan Vasantha , Paddock E. F. , Sharp W. R.
Published: September 2008

Explants were obtained from leaves of three strains of tomato and grown on a modified Murashige and Skoog's medium with various combinations of indole-3-acetic acid (IAA) and kinetin. Callus proliferation began by 8–10 days. Root initiation was very common, particularly at 2 mg/liter IAA and 2 mg/liter kinetin. Shoot formation occurred within 30 days but only at a specific combination of concentrations of the two growth hormones (4 mg/liter IAA + 4 mg/liter kinetin). Most shoots became plantlets by 10 days after transfer to basal Murashige and Skoog's medium. Shoot-forming potential was neither correlated with callus-forming potential nor with vigor of strain.
Zonation and regulation of old pasture populations of Hieracium floribundum
Authors: Thomas A. G. , Dale H. M.
Published: September 2008

Colonies of the perennial Hieracium floribundum Wimm. and Grab, had four zones, identified by the density of the rosettes. Belts of sod were analyzed to determine the characteristics of these zones in a pasture which had not been grazed for 5 years. The advancing outer zone consisted of widely spaced rosettes that were less than 2 years old. These rosettes had short rhizomes and large leaves, reproduced by stolons, and flowered abundantly, producing numerous heads per inflorescence. In the central zone, which had the highest density, the rosettes were more than 2 years old, had long rhizomes and small leaves, and did not flower. Seedling numbers were insignificant in all zones. In this species stolons are produced only on plants that have flowered. At high densities curtailment of population growth resulted from reduced flower production and the number of associated stolons initiated per flowering plant.
Cell walls in Cucurbita maxima cotyledons in relation to imbibition
Authors: Lott John N. A.
Published: September 2008

The scanning electron microscope and the freeze-etch technique were used to demonstrate the presence of corrugated cell walls in cotyledon mesophyll cells from dry squash seeds. These wavy cell walls straightened out during imbibition. In the scanning electron micrographs no wavy cell walls were observed in the smaller epidermal cells. Tissue imbibed for 2 h and then air-dried contained corrugated cell walls, whereas similar imbibed tissue dehydrated in ethanol and propylene oxide contained smooth cell walls. Thus the method of seed dehydration is important in determining the appearance of wavy cell walls. Glutaraldehyde fixation during the 2-h imbibition process did not alter the conditions under which wavy cell walls reappear.
Clonal variation in the incidence of Hypoxylon canker on trembling aspen
Authors: Copony James A. , Barnes Burton V.
Published: September 2008

The incidence of Hypoxylon canker, caused by Hypoxylon mammatum (Whal.) Miller, on ramets of 80 pole-sized Populus iremuloides clones was determined on three sites near Pellston, Michigan, and two sites near Iron River, Michigan. Variation in the incidence of canker within clones was slight. No significant difference (P >.05) in canker incidence was found among NE, SE, SW, and NW quadrants of 47 clones on the Pellston Plain site. Significant differences (P <.005) were found among clones in the incidence of canker in four of the five sites studied. In some cases, nearby or adjacent pairs of clones showed significant and striking differences in the incidence of canker infection. The range in canker incidence (percentage of living and dead ramets with stem or branch cankers) for all clones was 9 to 90%; the range was wide on all sites. Low stand density and light bark color of ramets were both significantly (P <.01 and P <.05, respectively) correlated with high canker infection.Although genetic differences between clones in the incidence of canker were not proven, the marked phenotypic differences among clones and other findings suggested moderate genetic control on four of the five sites investigated. In studies relating the incidence of canker to site and biotic factors, the clonal structure of aspen stands should be recognized, and the clone should be used as the basic unit of sampling.
Biochemical and physiological studies on dormancy release in tree buds. III. Changes in endogenous growth substances and a possible mechanism of dormancy release in overwintering vegetative buds of Populus balsamifera
Authors: Bachelard E. P. , Wightman F.
Published: September 2008

Variations in the amounts of auxins, gibberellins, and inhibitors in vegetative buds of Populus balsamifera L. with the passage from winter dormancy to the spring flush of growth were examined using bioassay techniques. The patterns of change found for gibberellins and inhibitors and for the ratios between them were similar to the patterns reported earlier (Bachelard and Wightman 1973, unpublished) in the physiology and biochemistry of the buds.These results, and others reported in the literature, suggest a possible mechanism of dormancy release and subsequent growth from the buds. This mechanism involves gibberellins, inhibitors, and cytokinins and focusses attention on the coordination of growth in the whole plant.
Microinjection of 14C-sucrose and other tracers into isolated phloem strands of Heracleum
Authors: Knight B. W. , Mitton G. D. , Davidson H. R. , Fensom D. S.
Published: September 2008

Microinjection of solutions of 14C-sucrose, 14C-aspartic acid, K332PO4, 42KCl, and 3HHO have all been made into living sieve elements of displaced, isolated, phloem strands of Heracleum. The profile of tracer movement is reported in experiments between 1 min 40 s and 8 min in duration in strands prepared both with and without callose-reducing buffer under conditions where lateral transfer of tracer is restricted. Two types of translocation patterns are discernable, a mass flow near the origin and a type of pulse flow superimposed on it and extending along the strands in both directions simultaneously. Some 42K and 32P has been detected with the 14C in the pulses, but 14C-sucrose also appears to move independently of the other tracers.
Some new or poorly known rusts of Brassicaceae
Authors: Savile D. B. O.
Published: September 2008

New data or amended descriptions are given for Puccinia aberrans, P. arabicola, P. dentariae, P. drabae, P. eutremae, P. oudemansii, and P. utahensis. P. dentariae var. sublevis var. nov., on Dentaria tenella, and P. drabicola sp. nov., on Draba incerta and Draba spp., are named.
Studies on the nature of the adaptations of the monkey flower, Mimulus guttatus, to a thermophilic environment
Authors: Delmer Deborah Pierson
Published: September 2008

The banks of many of the hot springs in Yellowstone National Park (U.S.A.) are populated almost exclusively by the wild flower Mimulus guttatus. Studies were undertaken to attempt to determine the nature of the adaptations this species possesses to enable it to survive in this thermophilic environment. Measurements of the heat stabilities of cytoplasmic proteins from this plant provide no evidence to indicate any unusual thermostable properties at the biochemical level. Similarly, the temperature optimum for growth of this species in tissue culture is not dramatically different from that of tissue taken from related or unrelated plants. Since this species has no obvious detectable differences in thermostability at the biochemical and cellular level, it is concluded that its ability to populate these areas may be primarily due to its hydrophytic nature as well as its ability to reproduce vegetatively.
Identification d'une cytokinine par chromatographic en phase gazeuse à partir de cultures pures de Taphrina cerasi
Authors: Barthe Phillipe , Bulard Camille
Published: September 2008

The ascomycete Taphrina cerasi (Fuck.) Sad., which induces malformations known as "witches’ brooms," when cultured in liquid media releases cytokinins. One of these, isolated from culture filtrates by ethyl acetate extraction, was identified as zeatin by paper chromatography, a biological test, and gas-liquid chromatography.
Histochemistry of RNA during pollen tube growth and early embryogenesis in eastern white pine
Authors: Shafer T. H. , Kriebel H. B.
Published: September 2008

Pinus strobus trees were crossed with pollen of the same species and with pollen of two non-crossable five-needle pines. Ovules were collected and sectioned during various phases of pollen tube growth and early embryogenesis. RNA was then localized by two staining methods coupled with enzymatic extraction. A layer of cells in the nucellus accumulates RNA in association with the growing pollen tube. The prothallial cells which will lyse to form the corrosion cavity are more rich in RNA than the surrounding cells both before fertilization and in the proembryo stages. Nucleolar RNA increases throughout the prothallium after suspensor elongation. The embryonic apex stains more intensely than do the suspensors, and intraspecific embryos stain more intensely than embryos of inviable hybrids.
Stomatal responses of five woody angiospasms to light intensity and humidity
Authors: Davies W. J. , Kozlowski T. T.
Published: September 2008

Stomatal responses to changes in light intensity and humidity were studied in green and chlorotic Fraxinus americana, Acer saccharum, Quercus macrocarpa, Citrus mitis, and Cercis canadensis seedlings. Stomatal closure occurred at higher light intensities in Acer than in other species. Transpiration was greater in Fraxinus and Quercus than in Citrus, Acer, or Cercis. Stomata opened faster than they closed in Fraxinus and Quercus and they closed faster than they opened in Citrus. Opening and closing rates were not significantly different from each other in Acer and Cercis. Stomata opened and closed faster in green than in chlorotic plants. In green plants, after a decrease in light intensity, species time to equilibrium of stomatal aperture was related as follows: Citrus < Acer < Quercus = Cercis < Fraxinus; and in chlorotic plants: Citrus < Acer = Quercus = Cercis < Fraxinus. After an increase in light intensity, stomatal opening time in green plants was related as follows: Citrus = Acer < Quercus < Cercis = Fraxinus. Stomatal opening in chlorotic plants was faster in Acer than in the other species, where stomata opened to equilibrium in about the same time. With changes in humidity from 20% to 80%, and the reverse, stomata of Fraxinus and Acer opened faster than they closed. Stomatal response to humidity was faster in Acer than in Fraxinus. Stomatal resistance was affected more by humidity changes at low light intensity (6500 lux) than at high intensity (32 000 lux). Postillumination CO2 bursts from leaves occurred in all species and were greater in green than in chlorotic plants. In both green and chlorotic plants, CO2 bursts varied as follows: Citrus > Quercus = Cercis > Fraxinus = Acer. Physiological responses of stomata are discussed in relation to leaf anatomy and metabolism.
Cycle cellulaire et teneurs en ADN nucléaire de cellules en suspension de l’Acer pseudoplatanus en phase exponentielle de croissance. Hétérogénéité de la culture
Authors: Rembur Jacques
Published: September 2008

The mean doubling time of Acer pseudoplatanus L. cell suspension cultures is 66 h during log-phase growth.A constant rate of proliferation and a stable mitotic index show this population to be asynchronous with little variation in the duration of the cell cycle.The results of both continuous and brief labelling show that only 84% of the cells divide. The cell cycle lasts 58 h with G1, S, G2, and M periods of 29, 21, 5.3, and 2.7 h respectively. G1 predominates while G2 is reduced.Microspectrophotometric analysis of nuclear DNA indicates a heterogeneous cell population made up of two proliferating groups, one diploid and the other tetraploid.The formation of tetraploids by endoreduplication and the possible evolution of both cell groups are discussed.
Somatic mitosis in haploid and diploid strains of Cochliobolus sativus
Authors: Huang H. C. , Tinline R. D.
Published: September 2008

From examination of living and doubly stained nuclei, somatic nuclear division in a haploid and a diploid strain of Cochliobolus sativus resembles conventional mitosis in that a metaphase-plate-like configuration and an associated fusiform spindle were present. However, a spindle pole body located at the spindle poles, the nucleolus, and presumably, the nuclear envelope persisted throughout the division cycle. During division, chromosomes contracted and the spindle elongated. At anaphase, lagging chromosomes were invariably observed.Within multinucleate cells there was variation in the degree of synchrony of nuclear division. Most, however, showed partial synchrony with the gradient direction basipetal in the diploid, acropetal in the haploid. Diploid and haploid nuclei also differed in size, in the size of spindle, number and probably in the size of chromatinic elements, and sometimes in the number of nucleoli. The haploid number of chromosomes appears to be six to eight.
Oospore production by a single isolate of Phytophthora capsici in the presence of chloroneb
Authors: Noon Jennifer P. , Hickman C. J.
Published: September 2008

A single isolate of the A2 compatibility type of P. capsici Leonian, a heterothallic species, was induced to form typical oogonia with amphigynous antheridia and oospores in agar cultures by the presence of chloroneb. Production of oospores continued when the cultures were maintained subsequently on medium with or without the chemical. These results suggest that chloroneb has brought about a permanent change in the ability of this isolate to form sex organs. Cultures also produced oospores when exposed to chloroneb vapor.
Agglutination and fusion of plant protoplasts by polyethylene glycol
Authors: Constabel F. , Kao K. N.
Published: September 2008

Protoplasts from pea leaves and Vicia hajastana cell cultures agglutinated tightly immediately after treatment with a concentrated solution of polyethylene glycol 6000. Pretreatment of the protoplasts with 0.01 g/liter lysozyme, 0.1 g/liter papain, 0.01% glutaraldehyde, and 0.01 g/liter lysolecithin reduced the agglutination. The results indicate that the integrity of the plasmalemma and electrostatic charges on the outer surface of the membrane are necessary for the polyethylene glycol- (PEG-) induced agglutination. Reduced agglutination, in general, resulted in a decrease in the percentage of fusion products. Pretreatment of protoplasts with 0.1 g/liter lysozyme, however, appeared to promote the formation of heterokaryocytes despite the lower degree of agglutination.
Floral development of Ruppia maritima var. maritima
Authors: Posluszny U. , Sattler R.
Published: September 2008

A hyaline, unvascularized sheath envelops a portion of the inflorescence near maturity. Though resembling an appendage of the main axis, in early ontogeny it develops as a prophyll of the renewal growth apex below the inflorescence. Two flowers develop on the inflorescence axis, subopposite each other. Fertile appendages are initiated in an acropetal sequence on each floral bud. The first to form, in the median position, are the two stamens, the lower preceding the upper. Each stamen develops two bisporangiate thecae separated by a broad connective. A dorsiventral outgrowth is initiated slightly abaxially near the tip of the connective at the stage of theca differentiation. This outgrowth appears to be homologous with a similar outgrowth in Potamogeton densus, but not with the sterile appendages of the Potamogeton flower which, by some authors, have incorrectly been interpreted as connective outgrowths. Each carpel arises as a radial primordium which becomes peltate after its inception. One ovule is initiated at the adaxial portion (Querzone). The stigma becomes broad and flat, lobing at its margins. A slight outgrowth develops at the abaxial wall of the carpel. The floral apex has a two-layered tunica. The primordia of the stamens, carpels, and ovules arise by periclinal divisions in the second layer. Procambial development is acropetal following closely primordial inception. Each appendage, including the ovule, receives one procambial strand. The outgrowths of the connective and the carpel lack procambium.
An experimental study of hybridization and pollination in Salix (willow)
Authors: Argus George W.
Published: September 2008

Experimental crosses between Salix discolor, S. petiolaris, S. bebbiana, and S. lucida resulted in the synthetic hybrids S. discolor × petiolaris and S. bebbiana × petiolaris and their reciprocals. The cross S. bebbiana × discolor and all crosses involving S. lucida were unsuccessful. Field experiments on the mode of pollination of Salix revealed the presence of wind-borne pollen of S. discolor, S. petiolaris, and S. bebbiana, and seed was set by these species in the absence of insect vectors. They are suspected to be both entomophilous and anemophilous. Salix lucida did not set seeds under these conditions and it is hypothesized that it is fundamentally entomophilous. Evidence is presented that suggests that natural hybridization between S. discolor and S. petiolaris may be restricted by differences in flowering time and by pollen competition.
Occurrence of tobacco ringspot virus in sweet cherry
Authors: Stace-Smith Richard , Hansen A. Juergen
Published: September 2008

Tobacco ringspot virus was isolated from one tree in a 10-ac (4-ha) orchard of sweet cherry (Prunus avium) cv. Bing near Oliver in the Okanagan Valley. The symptoms on the infected tree included a light-green zonal discoloration and irregularity in shape of leaves. The virus was transmitted by budding to nine Prunus cultivars, some of which developed pronounced symptoms. It was sap-transmitted to Chenopodium quinoa, cucumber, and Nicotiana clevelandii. Antiserum produced from infected N. clevelandii was positive in tests using tobacco ringspot virus isolate from tobacco and blackberry.
Scanning ultrastructural ontogeny of cleistohymenial apothecia in the operculate Discomycete Ascobolus furfuraceus
Authors: O'Donnell K. L. , Fields W. G. , Hooper G. R.
Published: September 2008

Morphogenesis of cleistohymenial apothecia in Ascobolus furfuraceus Pers. ex Fr., a heterothallic operculate Discomycete (Pezizales, Ascobolaceae), was investigated with the scanning electron microscope from initiation of the ascogonial coils through ascospore discharge. Rupture of the ectal excipular roof generally occurs in the early mesohymenial to midmesohymenial phase. As a result of hymenial expansion and upward growth of the ental (medullary) excipulum, the hymenial surface changes from a concave to a convex form by the late mesohymenial phase. In the telohymenial phase, clavate operculate asci protrude up to 50% of their length above the surface of the hymenium.
Chlorophyll and carotenoids of the rin tomato mutant
Authors: Sink Jr. K. C. , Herner R. C. , Knowlton L. L.
Published: September 2008

Fruit of the rin tomato (Lycopersicon esculentum Mill.) mutant were analyzed for chlorophyll and carotenoid composition. Thirty days after pollination, rin fruit contained less chlorophyll a and more chlorophyll b, causing a lower a:b ratio than fruit of the normal ripening line. Phytoene, phytofluene, β-carotene, γ-carotene, and lycopene were all present in normal fruit 40–45 days old. In contrast, the carotenoids found in rin fruit were composed mostly of phytoene, with reduced quantities of β- and γ-carotene and traces of phytofluene and lycopene. Fruits of rin contained only phytoene and β-carotene after 180 days. These changes in endogenous pigments are interpreted as pleiotropic effects of the rin gene on the ripening tomato fruit. Pigmentation differences in fruit of the reciprocal hybrids were detected.
Growth and production of microsclerotia of two Cylindrocladium species with various carbon and nitrogen sources
Authors: Weaver D. J.
Published: September 2008

Galactose, glucose, maltose, and mannose supported optimum growth of Cylindrocladium scoparium in buffered liquid media. Growth of C. floridanum was maximum on cellobiose, sorbose, and xylose, but growth was only slight on maltose and galactose. Both fungi used several amino acids and grew well on peptone, ammonium nitrate, ammonium sulfate, potassium nitrate, sodium nitrate, and urea. Cylindrocladium floridanum grew well on sodium nitrite, but C. scoparium made only slight growth on this nitrogen source. Ammonium and nitrite compounds inhibited production of microsclerotia by both fungi. The fungi grew between pH 4.1 and 7.5 with optimum growth at pH 6.5. Numbers of microsclerotia produced were generally directly related to the amount of growth.
Microsporogenesis and pollen formation in lodgepole pine
Authors: Ho Rong H. , Owens John N.
Published: September 2008

Microsporogenesis and pollen formation of three coastal and two interior lodgepole pine (Pinus contorta Dougl.) trees, and microstrobili of the interior trees were studied. Microspore mother cells were at pachytene when first observed and they remained at pachytene until the end of March in the interior trees and until mid-April in the coastal trees. The stages from pachytene to pollen shedding took 1 month in the coastal and interior trees. Several abnormalities were found in chromosome behavior, cell wall formation, and pollen grains. The percentage of abnormalities was higher in the interior trees than in the coastal trees. Abnormalities in chromosome movement seem to be genetically influenced and may be attributed to the large chromosomes, and to the prolonged low temperatures during meiosis and pollen formation. For interior lodgepole pine, the average number of microstrobili per shoot is 19.6 with 8.3 bud scales per microstrobilus, 93.3 microsporophylls per microstrobilus, and 2491 pollen grains per microsporangium. It is estimated that each microstrobilus produces about 465 000 pollen grains and each shoot produces about 9 million. There are about 33.5 million pollen grains per gram of dry pollen in lodgepole pine.
Arctic plant communities east of the Mackenzie Delta
Authors: Corns Ian G. W.
Published: September 2008

Tundra vegetation was analyzed on the basis of 64 sampled and 12 described stands representing a wide variety of plant community types immediately east of the Mackenzie Delta, Northwest Territories. Five main types (Tall Shrub – Herb, Medium Shrub (alder), Low Shrub – Heath, Herb – Low Shrub – Heath, and Herb) and 11 subgroups were distinguished and classified on the basis of floristic similarity using a two-dimensional ordination and by physiognomy. A total of 70 species were sampled or observed in the stands. Floristically, the Sedge–Cottongrass–Heath type was the most diverse and the Wet-Sedge Polygon – Herb type, the least diverse. The areal extent of each major community type was determined using aerial photography for Richards Island, Caribou Hills, Eskimo Lakes, Tuktoyaktuk, and Atkinson Point study areas.
Investigations of growth-promoting factors in conditioned soybean root cells and in the liquid medium in which they grow: ammonium, glutamine, and amino acids
Authors: Sargent P. A. , King J.
Published: September 2008

Cells cultured in sterile, liquid media from a number of Phaseolus spp., soybean cotyledons, shoots, and roots and from rice explants grew, in terms of dry-weight increase, much better in the presence of NH4+ and NO3− as sources of nitrogen than with NO3− alone. Other cultures tested, including other legumes, either did not respond positively to added NH4+ or, as in the case of Haplopappus gracilis cells, grew better in its absence.Earlier it had been shown that soybean (Glycine max. L. cv. Mandarin) root cells grew better in the presence of NH4+ than in its absence and that 'conditioning' substances were produced by cells and excreted into the medium between about the 15th and 35th h of incubation. These observations and those above with other cell cultures led to the initiation of an investigation of why some cells respond to NH4+ while others do not.This investigation has so far taken the form of an analysis of nitrogenous compounds in soybean root cells and in the NH4+-containing medium in which they were grown during 120 h of incubation and especially after 24 h of incubation, the time of maximum production of growth-enhancing ability in both cells and medium.Growth enhancement can be accounted for, apparently, by the occurrence of residual NH4+ in conditioned medium and by the presumed occurrence of NH4+ in cells. However, glutamine and its derivatives are implicated in the conditioning process.
The epidemiology of common root rot in Manitou wheat: disease progression during the growing season
Authors: Verma P. R. , Morrall R. A. A. , Tinline R. D.
Published: September 2008

Common root rot in Triticum aestivum cultivar Manitou caused primarily by Cochliobolus sativus was followed during plant development in 1969, 1970, and 1971 at Matador, Saskatchewan. Plants were sampled at intervals, and three variables based mainly on the occurrence of lesions on subcrown internodes were studied: number of diseased plants per square meter; percentage of diseased plants; and disease rating which integrated percentage of diseased plants and disease severity on each plant. All variables increased with time, and the progression curves in all 3 years were hyperbolic, indicating that the increases were like those of a simple interest disease as described by Van der Plank. In two of the years, almost 100% of the plants were diseased considerably before the end of the season. The transformation proposed by Van der Plank for simple interest diseases, log10[1/(1 − x)], was applied to the percentages of diseased plants, and regressions were calculated. The slopes of these lines (infection rates) were as follows: 1969, 0.99% plants per day; 1970, 1.32%; and 1971, 1.96%. In 1969 the onset of disease was later than in 1970 and 1971, and there was correspondingly less disease at the end of the growing season.
Recovery of sporangia of Phytophthora cactorum from soil
Authors: Sneh B.
Published: September 2008

Sporangia present in soil germinated directly on soil dilution plates when a nutrient agar medium was used and the plates were incubated at 27 °C.