bluuebunny/crossref_metadata_2025 huggingface dataset:
Regional differences in hypericin and pseudohypericin concentrations and five morphological traits among Hypericum perforatum plants in the northwestern United States
Authors: Walker Loren , Sirvent Tara , Gibson Donna , Vance Nan
Published: June 2017

Geographic differences among Hypericum perforatum L. plants in concentration of two hypericins and five morphological characteristics were analyzed in plants collected from four sites each in northern California and western Montana and two sites in Oregon. Differences among regional collections of H. perforatum were assessed based on analysis of hypericin and pseudohypericin concentration in floral, leaf, and stem tissue; light and dark leaf gland density; leaf area; leaf length/width ratio; and stem height. Significant differences in morphological and biochemical traits were detected primarily between samples collected from California and Montana. California samples had higher concentrations of hypericins, greater leaf gland density, larger leaves, and taller stems than those from Montana. Overall, Oregon samples did not consistently differentiate from those of Montana and California. Seasonal differences in hypericins were analyzed in Oregon plants only. Mean floral concentration of pseudohypericin (0.29%) and hypericin (0.06%) were highest during anthesis coinciding with July and August sampling dates, whereas mean leaf concentrations (0.19 and 0.04%, respectively) were highest in August.Key words: Hypericum perforatum, hypericin, St. John's wort, leaf glands, noxious weed, medicinal plant.
Cyanide resistant respiration in Salix nigra endomycorrhizae
Authors: Antibus R. K. , Trappe J. M. , Linkins A. E.
Published: June 2017

The mycorrhizae and respiration of roots of Salix nigra Marsh., were investigated for plants growing on an abandoned railroad grade in Virginia. The plants were found to be heavily colonized with vesicular–arbuscular mycorrhizae when growing on this site. Glomus fasciculatus (Thaxter) Gerd. & Trappe was the only symbiont which could be unequivocally connected with these endomycorrhizal roots.Addition of 5.0 mM KCN to S. nigra endomycorrhizae or S. rotundifolia ectomycorrhizae inhibited respiration by approximately 50%, suggesting the possible involvement of a cyanide insensitive alternate oxidase in root respiration. Addition of 2.5 mM salicylhydroxamic acid (SHAM) to KCN inhibited roots caused an additional significant reduction of oxygen uptake in both root types. These results suggest the participation of a SHAM sensitive oxidase in the respiration of these roots. When SHAM was added alone to S. nigra endomycorrhizae a slight but insignificant reduction in oxygen uptake was observed. Conversely, SHAM caused a stimulation of oxygen uptake in S. rotundifolia ectomycorrhizae. When SHAM was followed by the addition of KCN the net result was a significant inhibition of respiration in both types of roots. These results indicate that an alternate oxidase exists in these endo- and ectomycorrhizal roots of willows which is characterized by some of the same basic features described for beech ectomycorrhizal roots.
15N-Isotope dilution as a measure of dinitrogen fixation by Azospirillum brasilense associated with maize
Authors: Rennie R. J.
Published: June 2017

The classical difference method (based on Kjeldahl determinations) and the 15N-isotope dilution method to measure dinitrogen fixation by Azospirillum brasilense associated with maize in vitro were compared. Both methods resulted in an accurate measure of the amount of Azospirilluin-fixed nitrogen found in the maize plant; 12.6% of the maize nitrogen was derived from the atmosphere. When sucrose, malate, or succinate was added as a carbon source to encourage dinitrogen fixation in the maize rhizosphere, atmosphere-derived nitrogen in the maize increased to 19.0, 28.0, and 38.0% of the total nitrogen (the remainder coming from seed nitrogen).
Septal ultrastructure in some genera of the Tremellaceae
Authors: Khan S. R. , Kimbrough J. W.
Published: June 2017

The fine structure of hyphal septa in the Tremellaceae has shown a number of modifications of the characteristic dolipore–parenthesome type septum. These variations appear of phylogenetic importance and systems of classification have been proposed based upon septal pore structure of a limited number of species. This study reports the fine structure of additional tremellaceous genera, Basidiodendron, Exidiopsis, Sebacina, and Tremellodendron. All species examined have dome-shaped pore caps bounded by unit membrane and with an electron-dense lamella in the pore cap lumen. Pore caps appeared nonperforate in Tremellodendron and Basidiodendron, while narrow discontinuations or distinct perforations were found in Exidiopsis and Sebacina. Thus, their pore cap architecture is similar to that of Exidia and other heterobasidiomycetes with the exception of species of Tremella and members of the Filobasidiaceae. It is suggested that schemes of classification based upon the fine structure of a limited number of taxa may be premature.
The extraction of photosynthate high in [11C]sucrose and its translocation in sunflower stems
Authors: Hayden D. B. , Fensom D. S. , Thompson R. G.
Published: June 2017

A technique has been developed to biosynthesize a water-soluble extract of 11C-labelled photosynthate high in [11C]sucrose. The extract can be produced in less than 1 half-life (20 min) and is of high activity. When 11C-labelled extract was fed to the individual vascular bundles of other living plants, 11C was taken up and translocated, and on the basis of direct and indirect evidence it was largely in the form of [11C]sucrose.11C-labelled extract, if fed to a flap or gentle scraping on the surface of a sunflower stem (or corn, cow-parsnip, pine, or elm) was translocated both apically and basally from the feed point. Incisions into xylem vessels produced very rapid tracer movements which seemed to be associated with xylem vessel liquid cavitation and also transpiration pull. Shallower cuts produced translocation patterns similar to 11CO2 leaf feedings and are thought to be largely in the phloem. Phloem transport was blocked by ice chilling; xylem transport was only slightly affected by ice, if at all. Phloem translocation profiles often displayed steps at the front of mass flow, and later appeared to have peaks of activity moving along them. The movements were sometimes rapid (>6 cm min−1) and appeared to be complex, as if different channels were conducting at different speeds in parallel.
Degradation of macromolecules by microfungi isolated from different podzolic soil horizons
Authors: Bååth E. , Söderström B.
Published: June 2017

The abilities of 60 species of soil microfungi to decompose protein, xylan, cellulose, and chitin were tested with an agar diffusion technique. Proteolytic capacity was shown by 51 species; 35 were xylanolytic, 31 were cellulolytic, and 23 were chitinolytic. The importance of the physiological capacities of soil fungi in determining the communities in different soil horizons is discussed.
Extension cellulaire, division cellulaire et niveaux de ploïdie des cellules corticales de l’épicotyle du pois en cours d'élongation
Authors: Nougarède A. , Rembur J.
Published: June 2017

During the elongation of the first pea epicotylary internode, three periods can be determined for the entire organ as well as for the cortical cells. The linear phase of elongation and the radial and tangential extension begin earlier for the cortical cells of the base than those in the apical region of the internode. The culture under dark conditions, which favors longitudinal growth, has no influence on the two other dimensions. During the 1st day following hydration the mitoses are at first diffuse, but on the 2nd day, they concentrate in the apical region in an intercalary meristem of more intense activity and with a longer life if culture takes place under dark rather than light conditions.In the apical region of the internode, the original cellular system is essentially diploid, whereas it is essentially tetraploid in the lower part. The physical conditions applied to plants (light or darkness) will only modulate the later evolution. On the 8th day, most nuclei of the apical region are tetraploid (light conditions) and octoploid (dark conditions). In the base region, under both dark and light conditions the octoploid level is obtained, but can be reached more rapidly if under dark conditions. In all cases, an increase in the nuclear volume precedes the increase in DNA content. The relation between cellular extension, mitoses and the ploidy levels are dealt with, as well as, the influence that the location of the cells in the internode has on the evolution of their polyploidization.
Effect of vanadium on the phosphatase activity of lichens
Authors: LeSueur P. , Puckett K. J.
Published: June 2017

Low vanadium concentrations (0.2 ppm) are shown to induce a significant reduction in the phosphatase activity of Cladina rangiferina and other lichens.
Influence de la température et de la durée d'un traitement cryoprotecteur sur la résistance au froid de plantules de blé. Étude ultrastructurale des nucléoles des ébauches foliaires
Authors: Gazeau Claude-Madeleine
Published: June 2017

The nucleolus is sensitive to cold-protective media and to low temperatures. Nucleolar changes observed in the leaf primordia of wheat seedlings were related to the impregnation medium (distilled water or a mixture of glycerol, dimethyl sulfoxide, and sucrose), to the temperature (20 or 2 °C), and to the duration of the pretreatment (1 to 12 days). The cryoprotective agent generated the formation of nucleoli "with a diffuse granular zone." If the impregnation was done at 2 °C, characteristic nucleoli "with an indented aspect" occurred. The longer the duration of the impregnation and the more intense the subsequent freezing, the more important were the nucleolar changes. On rewarming the seedlings the various transformations were shown to be reversible.
Genetic variation of lodgepole pine over time and microgeographical space
Authors: Knowles Peggy , Grant Michael C.
Published: June 2017

The genetic composition of Pinus contorta var. latifolia as determined by isozyme analysis was examined in terms of its variation over space and time. Four populations of lodgepole pine consisting of approximately 125 trees each were sampled along an elevational gradient spanning a distance of 2 km in the Front Range of the Rocky Mountains in Colorado. Four isozymes were electrophoretically resolved from needle tissue removed from each tree. Ages were estimated from ring counts of either a tree core or a basal cross section of each tree. Gene frequencies were submitted to two-way analyses of variance using a subsampling procedure to generate multiple estimates within each cell. Analyses were performed to examine the variation in gene frequencies for each of the seven alleles resolved, using site (spatial) and age (temporal) as the independent factors. The results indicated that spatial heterogeneity contributes more to variation in genetic composition of lodgepole pine than does temporal heterogeneity. These results support theoretical proposals that spatial environmental heterogeneity under certain conditions can have more effect on variation in genetic composition than does temporal heterogeneity. It is further concluded that under certain conditions the analysis of variance procedure can be a useful analytic tool for examining gene frequency differences.
Relationships between Hordeum bulbosum L. subsp. bulbosum and H. bulbosum subsp. nodosum comb, et stat. nov.
Authors: Baum Bernard R. , Bailey L. Grant
Published: June 2017

Material of the diploid (HBD) and tetraploid (HBT) Hordeum bulbosum collected in the Mediterranean and Near East areas was examined for 14 morphometric characters. Exploratory data analysis revealed that cilia on the margins of the glumes of the central spikelets may or may not be present in HBT but are never present in HBD. The data were submitted to various kinds of discriminant analysis in which group assignment was based on ploidy level. When presence–absence of cilia on glume margins is used in combination with the resulting linear discriminant functions (DF) there is about 91% probability of correct identification; with DF alone there is about 81% probability. The results of discriminant analysis provided justification, in the opinion of the authors, to regard HBD and HBT as separate taxa at the level of subspecies, namely H. bulbosum subsp. bulbosum and H. bulbosum L. subsp. nodosum (L.) Baum.
The isolation and cultivation of protoplasts from cell suspensions of a pantothenate-requiring auxotroph of Datura
Authors: Mii M. , Seeni S. , Fowke L. C. , King J.
Published: June 2017

Protoplasts isolated from Datura cells requiring pantothenate for growth (Pn1 cell line) failed to divide in a medium containing 0.5 M mannitol if the cells from which they were derived had been subcultured in liquid medium more than four times. Division could be reinduced either by increasing the concentration of 2,4-dichlorophenoxyacetic acid (2,4-D) in the growth medium from 1 to 2.5–5 mg/L, by adding low concentrations (0.01 – 1 mg/L) of benzyladenine to a growth medium containing 1 mg/L of 2,4-D, or by diluting the 0.5 M mannitol in the medium to 0.2 M immediately after isolation of the protoplasts. Thus, the physiological state of Pn1 cells seems to change significantly after only a few passages in liquid medium. These changes can be prevented or partially reversed by manipulating the medium in which the cells and protoplasts are cultured. Similar physiological changes did not occur in the case of cultured wild-type (Ph4), adenine-requiring (Ad1), or isoleucine–valine-requiring (I–VI) cells of Datura.
Uptake of gaseous sulphur dioxide by the lichen Cladina rangiferina
Authors: Grace B. , Gillespie T. J. , Puckett K. J.
Published: June 2017

Samples of the lichen Cladina rangiferina were exposed to various concentrations of sulphur dioxide in a fumigation cuvette system for time periods ranging from 1 to 18 h. The cuvette system provided airstreams which, within the limits of measurement, had identical flow rates, temperatures, and relative humidities. Sulphur dioxide was added to one airstream as a treatment, while the other remained free of sulphur dioxide for control purposes. In some experiments, wind speed could be varied from 8 to 250 cm∙s−1 in a small wind tunnel placed in the fumigation cuvette. The system allowed for the calculation of sulphur dioxide uptake by the lichen sample. Potassium release was shown to increase with an increasing uptake of sulphur dioxide (time-integrated flux), but was not uniquely related to sulphur dioxide concentration alone. Extrapolation of a linear transformation of the potassium release curve to zero potassium efflux resulted in a threshold uptake value of 240 μg SO2∙g lichen−1. Internal lichen resistance and lichen boundary-layer resistance were experimentally determined for later use in an electrical analog model for the calculation of sulphur dioxide uptake.
Sulphur dioxide threshold concentration values for Cladina rangiferina in the Mackenzie Valley, N.W.T.
Authors: Grace B. , Gillespie T. J. , Puckett K. J.
Published: June 2017

A simulation model for the prediction of threshold concentration values of gaseous sulphur dioxide for damage to Cladina rangiferina over a 24-h period is presented. The model requires inputs of near surface relative humidities and air temperatures as well as lichen surface temperatures, and nearby airport wind speeds. An initial value of percent lichen water content must also be specified. Studies of lichen water relationships provided expressions utilized in the model for the calculation of the percent lichen water content. The model was applied to four microclimatically different days for an open lichen–spruce woodland near Inuvik, N.W.T. Boundary-layer resistance was found to be not as important as internal thallus resistance to sulphur dioxide uptake. For all days examined, threshold gaseous concentration values of sulphur dioxide for a 24-h period ranged from 20 to 30 μg∙m−3.
Stigma development and the stigmatic cuticle of Medicago scutellata
Authors: Kreitner G. L. , Sorensen E. L.
Published: June 2017

The self-fertile annual Medicago species evolved from the cross-pollinated perennial species. We used light and electron microscopy to study the development and structure of the stigma in annual tetraploid Medicago scutellata (L.) Mill to help elucidate the mechanism of self-pollination. Immature stigmatic cells have extensive lipid deposits. During development, stigmatic cells become separated and cellular lipid is transferred to intercellular spaces as part of the copious stigmatic secretion. The cuticle of the stigma is lifted away from underlying cell walls and confines secretion around stigmatic cells. The cuticle is thin, about 75 nm, and is composed mainly of a single layer traversed by dense strands. The cuticle is virtually always disrupted during late stages of flower maturation, as evidenced by penetration of stain into the stigma. Self-pollination may occur without flower tripping.
First growing period development of Acer saccharum stump sprouts arising after different dates of cut
Authors: MacDonald Joanne E. , Powell G. R.
Published: June 2017

The study was conducted on a clear-cut area of the Nashwaak Experimental Watershed Project, New Brunswick. Thirty residual Acer saccharum Marsh, trees (6–10 cm diameter at breast height) were cut during the dormant period and at intervals during the subsequent growing period. Development of dominant and codominant sprouts on stumps of these trees was monitored. Rate of leaf pair and supporting internode production, number of leaf pairs and supporting internodes produced, rate of elongation of sprouts, total length of sprouts, rate of increase of lamina area, and total lamina area of sprouts decreased with each successive date of cut. Lamina area of successive leaf pairs and lengths of successive internodes increased acropetally to maxima and then decreased. Sylleptic shoots developed in axils of proximal leaf pairs. On sprouts arising after the dormant-period cut and after mid-June through mid-July cuts, terminal buds formed, whereas on sprouts arising after late July and August cuts, leaf pair and supporting internode production continued until meristems were killed by frost. On some sprouts arising after the dormant-period cut, adventitious roots were observed. The influence on sprout development of carbohydrate reserve levels, photoperiod, solar radiation, and depth of rest in dormant buds at the time of cut are discussed.
Developmental studies of the stratification–germination process in sugar maple embryos
Authors: Shih C. Y. , Dumbroff E. B. , Peterson Carol A.
Published: June 2017

Changes in the anatomy, morphology, and stored food reserves of stratifying (5 °C) sugar maple embryos were followed from a strongly dormant state through germination. The correlation of cell division and cell elongation with radicle protrusion was also investigated. No morphological or anatomical changes were observed before first maturation of phloem elements on the 17th day of stratification. Mature xylem elements were first observed on day 37, and first germination was noted on day 38. Radicle protrusion was initiated by cell elongation, and cell division was not active for several days after emergence and a marked increase in lengths of the axes had occurred. Changes in amounts of protein, lipid, and starch were not observed during the stratification period, but mobilization of stored reserves was clearly evident with emergence of the radicles. Several of these key events appeared to be closely associated with previously described peaks and patterns of growth regulator activity.
Flavonoid variation in the Senecio streptanthifolius complex
Authors: Bain John F. , Denford K. E.
Published: June 2017

Flavonoid characters are presented for seven "phases" (sensu Barkley 1962) of Senecio streptanthifolius Greene and four related species, Seneciopauperculus Michx., Senecio multilobatus T. & G., Senecio canus Hook., and Senecio neomexicaiius A. Gray. Evidence from the study of flavonoid characters supports the division of S. streptanthifolius into two subgroups; the subgroup composed of the suksdorfii and laetiflorus phases is apparently related to S. pauperculus. In the other subgroup, three of five phases have apparently arisen through a combination of hybridization and polyploidy or introgression. While the two subgroups are thought to have originated during the Pliocene, the within-subgroup hybridization events are hypothesized to have occurred in Pleistocene or post-Pleistocene times.
Effects of cotyledon removal on apple seedling growth and distribution of 14C-labelled photosynthates
Authors: Li Jia-Rui , Proctor J. T. A. , Murr D. P.
Published: June 2017

In very young apple (Malus domestica Borkh.) seedlings, cotyledon dry weight decreased during the 14-day period following cotyledon separation and development. Removal of both cotyledons at the time of cotyledon separation significantly reduced subsequent seedling development as measured by leaf area and leaf fresh and dry weights, but it did not alter established 14C-labelled photosynthate transport patterns. Cotyledon removal from seedlings with fully expanded cotyledons and four unfolded expanding true leaves did not affect subsequent seedling growth. Removal of one cotyledon in very young seedlings reduced retention and export and increased apparent metabolism of 14C-labelled photosynthate. Removal of one cotyledon in older seedlings to which 14CO2 was fed to the first true leaf did not influence retention, export, or metabolism of the 14C-labelled photosynthate in the fed leaf. In the early stages of seedling growth, assimilates were directed mainly to the lower stem and root system, then to the shoot apex and immature leaves, and finally again to the root system as the first true leaf assumed the function of supplying assimilates during cotyledonary senescence.
Variation of histological patterns in tobacco callus during successive subcultures
Authors: Floh Eny I. S. , Handro Walter
Published: June 2017

Stem pith sections from haploid, diploid, and polyploid plants of Nicotiana tabacum L. cv. Wisconsin-38 were cultured in dark or light, in RM-64 medium with different auxin–cytokinin balances, and were subcultured four times. An analysis of the distribution of five histological types in the calluses was made. Growth, external morphology, and structural pattern were closely related to the conditions of culture. When cultured in medium with 2.0 mg/L indoleacetic acid plus 0.2 mg/L kinetin, in the dark, the primary calluses exhibited marked differences in growth, external morphology, and histological pattern depending on the original ploidy. These differences disappeared after several subcultures, all calluses becoming compact with similar internal structure.
Triploidy and its evolutionary significance in Cystopteris protrusa
Authors: Haufler Christopher H. , Windham Michael D. , Britton Donald M. , Robinson Scott J.
Published: June 2017

The most widely recognized mode of polyploid formation in homosporous ferns is allopolyploidy. There are taxa, however, that appear to have arisen through autopolyploidy. Several widely separated collections of the normally diploid species Cystopteris protrusa were found to be triploid. Plants in these collections were morphologically similar to typical, diploid C. protrusa, exhibited a significant number of trivalents during meiosis, and corresponded allozymically to heterozygotes from diploid populations. These plants probably arose through outcrossing between normal, haploid gametes and unreduced, diploid gametes. It is hypothesized that this mechanism of autopolyploid formation is stimulated by environmental stress and may be an intermediate stage in the formation of sexually reproductive tetraploids.
Formation de globoïdes et de cristaux au cours de l'embryogenèse de Raphanus
Authors: Genevès Louis , Rutin Jacques , Halpern Sylvain
Published: June 2017

The formation of crystals rich in inorganic reserves was studied during the embryogenesis of Raphanus. Some crystals and globoids were detected in thin green cotyledons during the early phase of embryonic curvature. After a double fixation, a few crystals were distinct inside the intracytoplasmic developing protein bodies. After a single aldehydic fixation, dark crystals and globoids with or without crystals were observed; these structures multiplied quickly inside the maturing protein bodies. In prints derived from thin green cotyledons, various types of crystals similar to those derived from dry seeds were isolated. Microanalyses with X-ray spectrometry by wavelength dispersion show that the major sorts of crystals usually found in dry seeds were precociously formed. Depending on the case, they were rich in phosphorus, calcium, silicon, or iron. The elemental composition of each type was defined. In ultrathin sections, dark transitory threads with crystals or globoids were observed in some developing protein bodies. Some similar dark threads were obtained in prints without fixation. In addition, these could contain very small granules (diameter, 20 nm). These threads, although rich in phosphorus and calcium, had an elemental composition different from that of the enclosed crystals.
Heterokaryon formation in planta by genetically marked strains of Tilletia caries
Authors: Churchill A. C. L. , Mills Dallice
Published: June 2017

Genetically marked and wild-type haploid cultures of Tilletia caries were mixed and used as inocula to analyze their potential for heterokaryon formation in the susceptible spring wheat variety 'Red Bobs' (Triticum aestivum L.). Of the fungus-treated plants inoculated by hypodermic needle injection into the boot at the flag leaf stage, 30 to 64% proceeded to maturity; the remainder failed to head. Tilletia caries was recovered from each of 38 representative plants which failed to head and from 3 plants which headed but showed no visible signs of infection. None of the inoculations resulted in teliospore formation within mature heads or other plant tissues. Genetic analysis of hyphal fragments obtained from mycelium in infected plants indicated that a heterokaryon had formed in each of two pairings of different auxotrophic strains of the fungus. The number of nuclei present in hyphal cells was variable. However, secondary sporidia derived from the heterokaryon were mononucleate with one exception and exhibited the nutritional requirement of one or the other parental strain. Results are discussed in relation to the development of a system for mitotic and meiotic analysis of single gene traits in the bunt fungi.
Reproductive incompatibility barriers in crosses between Vaccinium corymbosum and V. elliottii
Authors: Munoz C. E. , Lyrene P. M.
Published: June 2017

A study was made of barriers to hybridization between tetraploid V. corymbosum L., the cultivated highbush blueberry, and V. elliottii Chapm., a wild diploid blueberry which may be useful in breeding cultivars adapted to the southeastern United States. Both prefertilization and postfertilization barriers were detected. Prefertilization barriers were mainly observed when V. elliottii was the male parent and were manifested as an arrest of pollen tube growth at the base of the style. In cases where fertilization did take place, regardless of which species was used as the female, a strong postfertilization barrier usually prevented development of hybrid zygotes. Zygotes remained in a resting state after fertilization and usually aborted before dividing. Meanwhile, the endosperm underwent four to six cycles of cell division before it started to degenerate. A causal relationship between embryo abortion and endosperm malfunction was not clearly established. Endosperm malfunction and embryo abortion were delayed when V. corymbosum was the female parent.
Allocation de biomasse et d'énergie chez deux espèces d'Aster (Asteracées) de milieux contrastants et chez leur hybride naturel
Authors: Lapointe Line , Simon Jean-Pierre
Published: June 2017

Patterns of allocation of biomass and calorie energy were investigated for 3 years in several populations of the following taxa: Aster acuminatus, A. nemoralis, and their natural hybrid Aster × blakei. Aster acuminatus, a forest understory species, allocates more biomass and energy to foliage and reproductive effort than the other two taxa. Aster nemoralis, a bog species, allocates more resources to stems and rhizomes than A. acuminatus and, although average total biomass values were lower, tissues had higher caloric values. For Aster × blakei, two groups of populations showing morphological introgression to either parent were also correlated with resource allocation patterns. Caloric and biomass resource allocation patterns of populations of the three taxa did not vary significantly over the 3-year study period, except for A. acuminatus where biomass was significantly lower in 1979 than in the other 2 years. Populations showing higher absolute biomass values had organs with lower energy values. However, when these values were expressed as percentages, the patterns of allocation of biomass and energy were not differentiated within each species. [Translated by the journal]
Pseudospiropes sp., a fungal epiphyte on living stems of striped maple (Acer pensylvanicum)
Authors: Harries Hinrich , Bärlocher Felix
Published: June 2017

The living stems of striped maple (Acer pensylvanicum L.) at two sites in Nova Scotia were found to be covered by a striking pattern of fungal hyphae belonging to Pseudospiropes sp. The fungus colonizes branches or seedlings during their first season, and the density of its coverage increases every year thereafter. The fungus was absent from striped maple at a site near Lake Placid, NY, and there is some evidence that its frequency of occurrence has declined elsewhere in the last few years. A pure culture of the fungus was unable to hydrolyze several plant cell wall polymers. It was able to use simple lipids, however, and its presence increased the erosion of the cutinized layer of striped maple stems. The fungus does not penetrate the stem surface, and its occurrence is not correlated with twig length or volume. It was absent from three sympatric maple species.
Ultrastructural observations on Helvellaceae (Pezizales). II. Ascosporogenesis of Gyromitra esculenta
Authors: Gibson Jack L. , Kimbrough James W.
Published: June 2017

The ultrastructure of ascosporogenesis in Gyromitra esculenta (Pers.) Fr. is examined and compared with that reported for other Pezizales. Observations are made on spore delimitation, primary wall deposition, and formation of the secondary wall. Primary wall formation is similar to that reported for other species of Pezizales. The more or less smooth, electron-dense secondary wall appears to be derived from loose, fibrillar material of the perisporal sac. Observations are also made on structure and origin of the epispore and on cytological details of the epiplasm and sporoplasm relating to spore ontogeny.
Major sclerotial polypeptides of psychrophilic fungi: temperature regulation of in vivo synthesis in vegetative hyphae
Authors: Newsted W. Jay , Huner N. P. A.
Published: June 2017

Western blot analysis of the major sclerotial polypeptides of the psychrophilic species Myriosclerotinia borealis (W51) and Coprinus psychromorbidus (LRS131) indicated that these polypeptides were not present in vegetative hyphae during growth at permissive temperature (5 °C), but significant accumulations were observed in hyphae upon prolonged exposure to nonpermissive temperature (25 °C). In contrast, low levels of sclerotial polypeptides were detected in the vegetative hyphae of Typhula incarnata (W29) and Typhula idahoensis (W21). We show, for the first time, that the in vivo synthesis of the major sclerotial polypeptides was induced when vegetative hyphae of M. borealis and C. psychromorbidus were shifted from 5 to 10 °C for 12 h. In contrast, vegetative hyphae of T. idahoensis and T. incarnata appeared to synthesize low levels of sclerotial polypeptides constitutively at 5 °C. Furthermore, a shift from 5 to 10 °C had little effect on the synthesis of major sclerotial polypeptides in the Typhula species. Prior exposure of vegetative hyphae from all species to 25 °C for 2 days caused a marked reduction in the capacity to synthesize sclerotial polypeptides. However, vegetative hyphae of T. incarnata synthesized a new polypeptide of 35 kDa that had not been detected previously. Antiserum to low molecular mass maize heat-shock polypeptides cross reacted with the major sclerotial polypeptides of T. idahoensis only. We conclude that the more psychrophilic species examined, M. borealis (W51) and C. psychromorbidus (LRS131), exhibit temperature-induced synthesis and accumulation of sclerotial polypeptides in vegetative hyphae. In contrast, sclerotial polypeptides of the less psychrophilic Typhula species appear to be expressed constitutively in vegetative hyphae.
A comparison of the stress responses of Zea mays seedlings as shown by qualitative changes in protein synthesis
Authors: Bonham-Smith P. C. , Kapoor M. , Bewley J. D.
Published: June 2017

Maize seedlings respond to heat shock, water stress, abscisic acid treatment, and wounding with the synthesis of stress-specific proteins. Unlike the almost instantaneous (10 min) heat-shock response, a much longer stress exposure is required before the synthesis of water stress induced, abscisic acid induced, or wound-induced proteins. As with heat shock, the protein profile of 24 h water stress induced proteins is consistent between tissue types, whereas seedling tissue response to wounding or heavy metals varies. Wounding of the mesocotyl for 12 h or more results in a complex change (induction and inhibition) in protein synthesis in the growing region, while protein synthesis in the nongrowing region is affected to a much lesser extent.
Dynamique d'une bordure forestière et variations récentes du niveau du fleuveSaint-Laurent
Authors: Bégin Yves , Lavoie Jean
Published: June 2017

The forested shoreline of the Saint Lawrence River upper estuary is frequently damaged by spring ice, currents, and waves during episodes of high water levels. A dendroecological analysis of the significant river floods, as recorded by ring-width patterns of uprooted woody plants, population growth and decay structures, and scars caused by ice on trees within the shore environment, provides direct evidence of a landward migrating shoreline. Regressive succession of vegetation is associated with a general rise in year-to-year flood levels. Plant community dynamics and shore sediment migration were investigated in a particularly exposed site between Grondines and Sainte-Anne-de-la-Pérade. Most of the oldest sublittoral trees are undergoing slow degradation and hydrophilous shrubby stands show extensive expansion within the shoreline habitat, which is associated with an important landward displacement of sediments. These ecological and geomorphological results concur with the general rising trend of flood levels of the Saint Lawrence during the last 30 years.
Proliférations épiphylles provoquées par l'acarien Eriophyes cladophthirus chez le Solanum lycopersicum et le Nicandra physaloides (Solanaceae)
Authors: Anthony Ming , Westphal Evelyne , Sattler Rolf
Published: June 2017

The acarian Eriophyes cladophthirus Nal. causes necrosis of the vegetative shoots of tomato and Nicandra and an inhibition and a modification of their apical growth, which are often accompanied by fasciation phenomena, the development of supernumerary buds and the proliferation of various shapes on the leaves. The foliar proliferations are warts, simple outgrowths, radially or dorsiventrally symmetrical appendices looking like small leaves and neoformed buds. In both species, intermediate forms of the various categories are found. The radially or dorsiventrally symmetrical appendices are simple or branched, vascularized or not, irregularly grouped or laid out in a more or less obvious phyllotaxy. They may appear directly on the leaf or may be the result of the activity of a neoformed apex. In this great diversity of shapes, many morphological continua, based on a number of criteria (symmetry, vascularization, etc.), have been identified. Some of them are common to both species, others only pertain to one or the other. [Journal translation]
Dicholobodigitus niger (Hyphomycetes), gen. et sp. nov.
Authors: White G. P. , Illman W. I.
Published: June 2017

A dark lignicolous hyphomycete with dichotomously branched conidiophores ending in clustered lobes giving rise to catenate, septate conidia is described and illustrated as Dicholobodigitus niger gen. et sp. nov.
The separation of Carex disticha and Carex sartwellii and the status of Carex disticha in North America
Authors: Catling P. M. , Reznicek A. A. , Brookes B. S.
Published: June 2017

To clarify the relationship between the Eurasian Carex disticha and the North American Carex sartwellii, 38 morphological characters were measured in 30 specimens of each. Various qualitative features were also scored. Through analysis of variance (ANOVA), a reduced number of 10 important continuous characters was obtained and the sample of each taxon was increased to 50. ANOVA of these 10 characters revealed that perigynium length and perigynium beak length were the most important discriminating characters, but in a scatter diagram of these two, 15% of the sample occupied a region of overlap. Principal-component analysis and discriminant analysis using the 10 characters resulted in a separation of the two groups, but a small region of overlap existed in both cases. The two taxa are distinct by virtue of accumulation of small morphological and other differences in a number of characters, rather than by sharp differentiation in a few characters. Carex disticha has larger perigynia with beaks (0.8–)1–1.5(–2.3) mm long, whereas C. sartwellii has smaller perigynia with beaks 0.4–1(–1.2) mm long. All distinguishing features are discussed and a key is provided. Immature vouchers for the occurrence of C. disticha in southwestern Quebec are confirmed on the basis of features of the inflorescence. The only other North American station of C. disticha, discovered in Simcoe Co., Ontario, in 1972 and extant in 1986, is also confirmed in the numerical analyses.
Furanocoumarins on the surface of callus cultures from species of the Rutaceae and Umbelliferae
Authors: Zobel Alicja M. , Brown Stewart A.
Published: June 2017

Four linear furanocoumarins (psoralen, xanthotoxin, isopimpinellin, and bergapten) were identified on the surfaces of callus cells of Ruta graveolens, Ruta pinnata, Daucus carota, and Pastinaca sativa in the concentration range of 0.055 – 1.1 μg total/g fresh weight. In some cases these surface deposits amounted to a substantial percentage of the total, with the highest (67%) in Daucus, but they were not always proportional to the total concentrations in the cells. Variation in the ratios of concentrations of the individual coumarins indicated selective extrusion. An unresolved mixture of isopimpinellin and bergapten, with the former predominating in the proportion of ca. 7:1, was extruded in the highest concentrations on brown callus. Shake cultures produced up to two orders of magnitude more furanocoumarins than callus cells and extrusion was accelerated, but the concentrations of particular exported furanocoumarins varied, again pointing to selective extrusion. Key words: callus, cell surface, furanocoumarins, Ruta, Daucus, Pastinaca.
Geographic patterns in the genetic diversity of a northern sedge,Carex rariflora
Authors: Vellend Mark , Waterway Marcia J
Published: June 2017

We compared the genetic diversity of a northern wetland sedge, Carex rariflora, both within and between populations, in different habitat types, and across geographic regions with different glacial histories. Twelve populations were sampled: 5 from each of two regions in northern Quebec, and 2 from northern Yukon. Habitat types were medium to rich fens, wet tidal flat, and alpine stream edge. Allele frequency data revealed a low degree of within-population genetic diversity (HS= 0.07) and a high degree of genetic differentiation among populations (GST= 0.47) compared with previously studied northern wetland Carex species. Higher genetic variability found in the Yukon than in Quebec could be explained by the presence of a glacial refugium in much of Alaska and the Yukon throughout the Pleistocene. Low genetic diversity in Quebec suggests the occurrence of genetic bottlenecks resulting from founder effects during postglacial colonization. There was a strong positive correlation between geographic distance and genetic distance among populations, and the three geographic regions were genetically distinct from one another. Detrended correspondence analysis of vegetation data revealed clear differences among the three habitat types, but we found no significant correlation between habitat differences and genetic distance.Key words: allozyme variation, genetic diversity, geographic variation, Carex rariflora.
Sur la présence d'une nouvelle espèce d'Isoetites dans la flore du Crétacé inférieur de la région de Tataouine (Sud tunisien) : implications paléoclimatiques et phylogénétiques
Authors: Barale Georges
Published: June 2017

Fossil plant compressions belonging to Isoetales have been discovered, for the first time, in clay from the Lower Cretaceous of Merbah el Asfer, Tataouine area (south Tunisia). The study of leafy corms and sporophylls has permitted us to attribute the fossils to the genus Isoetites Münster. The comparison between the known Mesozoic material leads to the description of a new species : I. daharensis nov.sp. Its affinities with Isoetes and with Triassic species show that the Isoetales were differentiated before the beginning of the Mesozoic era, and since then this lineage has shown little morphological variation. The good preservation of fossils is evidence of short transportation in a deltaic plain with sufficient moisture to permit the growth and development of these plants.Key words: Isoetales, Isoetites, Lower Cretaceous, Tunisia, phylogeny, palaeoecology.
Growth and vegetative spread of Schizachyrium scoparium var. littoralis (Poaceae) in sand dune microhabitats along a successional gradient
Authors: Valverde Teresa , Pisanty Irene
Published: June 2017

The architecture resulting from the iteration of modules during plant growth affects resource capture. Phalanx and guerrilla growth forms have been described as ends of a continuum regarding the spacing of modules in plants. In this study we investigated the growth form of the perennial, tussock-forming grass Schizachyrium scoparium Michx. var. littoralis (Nash) Hitchc. in three dune microhabitats at El Morro de la Mancha, southeastern Mexico: a mobile, a semi-mobile, and a stabilized site. We followed the growth of 15 genets at each site for two consecutive years and found that daughter-tussock formation was more frequent in the stabilized than in the semi-mobile or the mobile sites. Individual tussocks had a higher number of tillers in the mobile site than in the other two. Tiller production occurred within parental tussocks in the mobile site and in the form of daughter tussocks in the stabilized site. Reciprocal transplants suggested that phenotypic plasticity was responsible for the differences observed. Fertilization enhanced tiller production within parental tussocks but did not affect daughter tussock formation. Clearing experiments resulted in enhanced tiller production within tussocks. In these experiments, daughter-tussock production did not occur directionally towards nutrient-rich microsites. It appears that S. scoparium tillers are spaced at longer distances when resources are scarce and intraclonal competition is severe.Key words: clonal growth, growth form, nutrient availability, phalanx-guerrilla continuum.
Temporal variations in isolation frequency of endophytic fungi of Japanese beech
Authors: Sahashi Norio , Kubono Takanori , Miyasawa Yukiko , Ito Shin'ichiro
Published: June 2017

To determine the dominant fungal endophytes of the Japanese beech (Fagus crenata Blume) and to monitor their isolation frequency, we isolated fungi from symptomless organs of beech including leaves, petioles, and current and old (1- to 5-year-old) twigs after surface sterilization. Of the 13 fungal taxa obtained, 3 were isolated most often. An unidentified species of Discula and an unidentified sterile fungus, Lb, were isolated frequently from leaves, and an unidentified species of Phomopsis was isolated most frequently from twigs. The isolation frequency over the growing season varied for the two dominant fungal species in the leaves, Discula sp. and Lb. These two species had similar patterns of isolation, even in petioles and current-year twigs, although isolation frequencies of a given species varied with organs. An organ-specific distribution of the fungal species in the host plant was apparent. The three fungal species noted above were considered to be the dominant endophytes of the Japanese beech.Key words: fungal endophyte, Fagus crenata, isolation frequency, organ specificity.
Chloroplastic changes associated with paclobutrazol-induced stress protection in maize seedlings
Authors: Sopher Coralie R , Król Marianna , Huner Norman PA , Moore Andrew E , Fletcher R Austin
Published: June 2017

In plants the chloroplast is a major site of free radical production and paclobutrazol protects plants by increasing antioxidant defense systems. Leaves from paclobutrazol-treated maize (Zea mays L. cv. Pioneer 3902 and Pride 5) had larger chloroplasts and grana stacks, and more stromal lamellae. Treated leaves had more epicuticular wax and were thicker and wider owing to enlarged vascular bundles, epidermal, mesophyll, and bundle sheath cells. Paclobutrazol increased survival rate following chilling (2°C for 8 h) and alleviated damage symptoms owing to chilling and exposure to paraquat (60 and 120 nM) in 'Pioneer' and 'Pride', the degree of protection being greater in 'Pride' (a less stress tolerant cultivar). Violaxanthin and lutein levels were higher in treated etiolated and light-grown plants. During photoinhibitory conditions of 5°C and 1300 µmol m-2 s-1 there was less interconversion of violaxanthin to zeaxanthin in treated leaves. Dissociation of grana, changes in the osmiophillic properties of the thylakoids, decreased Fv/Fm ratio, and ion leakage occurred earlier and at a faster rate in control leaves. Protection from paraquat and photoinhibitory damage in maize leaves by paclobutrazol indicates that treated plants have a more efficient free radical scavenging system.Key words: chloroplast, paclobutrazol, stress, triazole, xanthophyll, Zea mays.
Carbon allocation in Euphorbia esula and neighbours after defoliation
Authors: Olson Bret E , Wallander Roseann T
Published: June 2017

Weeds increase their dominance in a grazed plant community by avoiding herbivory and (or) by tolerating herbivory more than neighbouring plants. After defoliation, allocating carbon to shoots at the expense of roots may confer tolerance. We determined carbon allocation patterns of undefoliated and recently defoliated (75% clipping level) plants of the invasive leafy spurge (Euphorbia esula L.) growing with alfalfa (Medicago sativa L.), Kentucky bluegrass (Poa pratensis L.), or Idaho fescue (Festuca idahoensis Elmer). Plants were labeled with 13CO2 24 h after clipping to determine allocation patterns; all plants had equal access to the 13CO2. Based on relative distribution of 13C, defoliation did not affect the amount of carbon allocated to roots of E. esula. The amount of carbon allocated to shoots of E. esula was higher when growing with P. pratensis than when growing with the other species. Based on relative enrichment of 13C, defoliation increased sink strength of remaining shoots on defoliated E. esula plants. Conversely, roots of unclipped E. esula plants were stronger sinks for carbon than roots of clipped plants. Even though defoliation increased "sink strength" of remaining shoots of E. esula, the amount of carbon allocated to the root system was unaffected by defoliation, suggesting that uninterrupted allocation of carbon to its extensive root system, not increased allocation to its shoot system, confers grazing tolerance.