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PubMed2001

Effects of consolidated tailings water on red-osier dogwood (Cornus stolonifera Michx) seedlings.

As part of their tailings management, the oil sand industries plan on producing consolidated (composite) tailings (CT), in which an inorganic coagulant aid (gypsum) is added to create a non-segregating deposit. The water associated with this treatment contains potentially phytotoxic levels of sodium, sulfate, chloride, boron, aluminum, fluoride and strontium. Since CT water is expected to saturate deposits in the reclamation areas, it may affect successful reclamation of these sites. Red-osier dogwood (Cornus stolonifera Michx) was demonstrated to be relatively salt resistant and to have high potential for the reclamation of mining areas. In the present study, we used red-osier dogwood to examine the effects of CT water on the accumulation of ions within plant tissue, growth, gas exchange, water potentials and chlorophyll concentration. CT water reduced shoot lengths and dry weights in treated plants. The roots of treated plants accumulated higher concentrations of sodium and chloride than did shoots. The accumulation of sodium and chloride was accompanied by an increase in magnesium and calcium and a decrease in potassium in the roots, while the levels of potassium increased in the leaves. CT water altered gas exchange and water potentials in seedlings, and resulted in a decrease in chlorophyll's a and b. The results suggest that the mechanisms of salt resistance in red-osier dogwood seedlings involve the restriction of sodium transport from roots to shoots.

Environmental Pollution↗
PubMed2001

Metabolic inhibition of root water flow in red-osier dogwood (Cornus stolonifera) seedlings.

The short-term effects of sodium azide (NaN(3)) on water flow in red-osier dogwood (Cornus stolonifera Michx.) seedlings were examined in excised roots at a constant pressure of 0.3 MPa. NaN(3) significantly decreased root water flow rates (Q(v)). It also induced a significant reduction in root respiration and reduced stomatal conductance to a greater extent in intact seedlings than in excised shoots. Apoplastic flow of water increased with the NaN(3)-induced decreases in Q(v). Mercuric chloride (HgCl(2)) was also used to characterize the water flow responses and respiration of dogwood roots. Similarly to NaN(3), 0.1 and 0.3 mM HgCl(2) decreased root respiration rates and Q(v). The lower, 0.05 mM HgCl(2) treatment, reduced Q(v), but had no significant effect on root oxygen uptake. The reduction of Q(v) in HgCl(2)-treated plants was only partly reversed by 50 mM mercaptoethanol. The mercurial inhibition of Q(v) suggested the presence of Hg-sensitive water channels in dogwood roots. The results indicate that root-absorbed NaN(3) metabolically inhibited water channel activities in roots and in shoots and resulted in stomatal closure. It is suggested that the inhibition of respiration that occurs in plants stressed with environmental factors such as flooding, cold soils, and drought may be responsible for the closure of water channels in root cells and inhibition of root water flow.

Aquaporins↗
PubMed1993

Seasonal variations in soluble sugars and starch within woody stems of Cornus sericea L.

Carbohydrate composition changed seasonally in red osier dogwood (Cornus sericea L.) stem tissues. Starch concentration was highest in fall and decreased to a minimum in midwinter. Coincident with the breakdown of starch in fall, there was an increase in the concentrations of soluble sugars. Soluble sugars were present in highest concentrations in midwinter. Glucose, fructose, sucrose, and raffinose were the predominant soluble sugars present in both bark and wood tissues. In early spring, the soluble sugar concentration decreased and the concentration of starch increased. The seasonal interchange between sugars and starch did not simply reflect a general quantitative shift in the balance between sugars and starch because qualitative changes in soluble sugars were also noted. The most striking changes involved the trisaccharide raffinose. Raffinose was barely detectable in summer and early fall, but increased to one fifth and one third of the total soluble sugars in January samples of bark and wood tissues, respectively. The potential physiological role of raffinose in overwintering red osier dogwood tissue is discussed.

Journal Article↗
PubMed1993

Ultrastructural Evidence That Intracellular Ice Formation and Possibly Cavitation Are the Sources of Freezing Injury in Supercooling Wood Tissue of Cornus florida L.

Although cellular injury in some woody plants has been correlated with freezing of supercooled water, there is no direct evidence that intracellular ice formation is responsible for the injury. In this study we tested the hypothesis that injury to xylem ray parenchyma cells in supercooling tissues is caused by intracellular ice formation. The ultrastructure of freezing-stress response in xylem ray parenchyma cells of flowering dogwood (Cornus florida L.) was determined in tissue prepared by freeze substitution. Wood tissue was collected in the winter, spring, and summer of 1992. Specimens were cooled from 0 to -60[deg]C at a rate of 5[deg]C h-1. Freezing stress did not affect the structural organization of wood tissue, but xylem ray parenchyma cells suffered severe injury in the form of intracellular ice crystals. The temperatures at which the ice crystals were first observed depended on the season in which the tissue was collected. Intracellular ice formation was observed at -20, -10, and -5[deg]C in winter, spring, and summer, respectively. Another type of freezing injury was manifested by fragmented protoplasm with indistinguishable plasma membranes and damaged cell ultrastructure but no evidence of intracellular ice. Intracellular cavitation may be a source of freezing injury in xylem ray parenchyma cells of flowering dogwood.

Journal Article↗
PubMed1994

Response of Xylem Ray Parenchyma Cells of Red Osier Dogwood (Cornus sericea L.) to Freezing Stress (Microscopic Evidence of Protoplasm Contraction).

Freezing behavior of wood tissue of red osier dogwood (Cornus sericea L.) cannot be explained by current concepts of freezing resistance. Previous studies indicated that water in wood tissue presumably froze extracellularly. However, it was observed that xylem ray parenchyma cells within these tissues could survive temperatures as low as -80[deg]C and the walls of these cells did not collapse during freezing (S.R. Malone and E.N. Ashworth [1991] Plant Physiol 95: 871-881). This observation was unexpected and is inconsistent with the current hypothesis of cell response during freezing. Hence, the objective of our study was to further examine the mechanism of freezing resistance of wood tissue of red osier dogwood. We studied freezing stress response of xylem ray parenchyma cells of red osier dogwood using freeze substitution and transmission electron microscopy. Wood samples were collected in winter, spring, and summer of 1992. Specimens were cooled from 0[deg]C to -60[deg]C at 5[deg]C/h. Freezing stress did not affect the structural organization of wood tissue. However, the xylem ray parenchyma cells showed two unique responses to a freezing stress: protoplasm contraction and protoplasm fragmentation. Protoplasm contraction was evident at all freezing temperatures and in tissues collected at different times of the year. Cells with fragmented protoplasm, however, were noticed only in tissues collected in spring and summer. Protoplasm contraction in winter tissue occurred without apparent damage to the protoplasm. In contrast, protoplasm contraction in spring and summer tissues was accompanied by substantial damage. No evidence of intracellular ice formation was observed in parenchyma cells exposed to freezing stress. Differences in protoplasm contraction and appearance of cells with fragmented protoplasm likely indicated seasonal changes in cold hardiness of the wood tissue of red osier dogwood. We speculate that the appearance of fragmented protoplasm may indicate that cells are being injured by an alternative mechanism in spring and summer.

Journal Article↗
PubMed1971

Induction of Cold Acclimation in Cornus stolonifera Michx.

A warm (20 to 15 Celsius day or night) preconditioning treatment enhanced cold acclimation of Cornus stolonifera bark under short-day conditions when plants were preconditioned for at least 4 weeks. Warm preconditioning inhibited the acclimation of plants subjected to long photoperiods. Removing leaves from plants exposed to low temperatures and short days inhibited acclimation. Removal of buds did not affect acclimation. Plants did not acclimate unless they were exposed to at least 4 weeks of short photoperiods prior to defoliation. Plants began to acclimate to cold at the time of growth cessation but not before. When half of the leaves were removed from plants, the defoliated and foliated branches both acclimated as well as branches on completely foliated plants. Girdling the phloem between foliated and defoliated branches prevented acclimation of the latter regardless of the position of the girdle in relation to the root system and the defoliated branch. When all of the leaves of plants were covered with aluminum foil to exclude light after 0 or 4 weeks of exposure to short days, the results resembled a defoliation study, i.e., plants with leaves covered at the start of the experiment failed to acclimate, and those covered after 4 weeks acclimated to some extent but less than uncovered control plants. Under longday conditions plants with all leaves covered failed to acclimate, and plants with none or half of their leaves covered acclimated equally and to a limited extent. Under short-day conditions, however, the covered branches of partially covered plants acclimated more than their uncovered counterparts or branches of totally uncovered plants.

Journal Article↗
PubMed1971

Relationship of Electrical Conductance at Two Frequencies to Cold Injury and Acclimation in Cornus stolonifera Michx.

The ratio of electrical conductance measured at two frequencies can be used to predict the cold hardiness of stem sections of Cornus stolonifera Michx. during the first stage of cold acclimation. Electrical conductance at 50 hertz divided by electrical conductance at 100 kilohertz gave a better estimate of hardiness than measurements at either frequency alone. The observed increase in the electrical conductance ratio as hardiness increased is consistent with an increase in membrane permeability. After plants were exposed to nonlethal frost, hardiness increased rapidly, and the relation between the conductance ratio and hardiness changed. This change indicates that ice crystallization induces a significant physiological alteration in the plants. Contrary to expectations, stem sections exposed to lethal temperatures could not consistently be separated from sections exposed to nonlethal temperatures by electrical conductance ratio measurements made immediately after thawing.

Journal Article↗
PubMed1974

Effects of Red and Far Red Light on the Initiation of Cold Acclimation in Cornus stolonifera Michx.

Red and far red light distinctly influence the initial phytochrome-mediated phase of cold acclimation in red-osier dogwood (Cornus stolonifera). Under controlled conditions, short days and end-of-day far red light exposure after long days promote growth cessation, cold acclimation, and subsequent cold hardening of dogwood stems in response to low temperature. Nuclear magnetic resonance absorption spectra of the water in internode stem sections imply that the short day-induced phase of cold acclimation involves a change in tissue hydration, at least in part, due to a substantial reduction in bulk phase water as a result of senescence and loss of water from the pith. Seasonal responses to light and an attempt to induce early acclimation under natural conditions with end-of-day far red light are discussed.

Journal Article↗
PubMed1974

Water Permeability and Cold Hardiness of Cortex Cells in Cornus stolonifera Michx.-A Preliminary Report.

The relationship of freezing resistance to water permeability of cortex cells was studied in stems of red osier dogwood (Cornus stolonifera Michx.). Permeability was estimated by determining the diffusion flux of tritiated water from cortex slices previously equilibrated in tritiated water. Energy of activation and diffusion time comparisons of tritiated water flux from living cortex slices and slices killed by immersion in liquid N(2) verified that intact membranes of uninjured cortex cells limited water flux.Water permeability of living phloem and cortical parenchyma cells increased during the initial (photoperiodically induced) phase of cold acclimation. This accompanied an increase in hardiness from -3 to -12 C. Little if any further increase in permeability was noted during subsequent acclimation to below -65 C.Permeability measurements on nonhardy cortex samples yielded consistent results, but measurements on samples from hardy twigs were often difficult to reproduce. This unexplained variability precludes specific conclusions, but the tritiated water diffusion flux technique may provide an alternative to traditional plasmolytic techniques in studying water permeability in woody plant tissues.

Journal Article↗
PubMed1977

Induction of Frost Hardiness in Stem Cortical Tissues of Cornus stolonifera Michx. by Water Stress: I. Unfrozen Water in Cortical Tissues and Water Status in Plants and Soil.

Water supply and day length were varied in cold hardiness studies of red osier dogwood plants (Cornus stolonifera Michx.). The frost killing temperature, the content and freezing of stem cortical tissue water along with soil moisture content and tension were evaluated. Seven days of water stress in long and short day photoperiod regimes caused a rapid decrease in soil moisture content and plant water potential. During the same period, the frost hardiness increased from -3 to -11 C. Further water stress treatment had little effect. Control plants in short days showed only a gradual decrease in plant water potential and only gradually increased in frost hardiness while control plants in long days were unchanged. Freezing studies using nuclear magnetic resonance showed that increased hardiness in water-stressed plants resulted from both an increased tolerance of freezing and an increased avoidance of freezing, the latter resulting from higher solute concentration in the tissue solutions. The short day controls also showed similar changes; however, the changes were smaller over the 21 days of the study.

Journal Article↗
PubMed1977

Induction of Frost Hardiness in Stem Cortical Tissues of Cornus stolonifera Michx. by Water Stress: II. Biochemical Changes.

A decrease of protein, RNAs, and starch, and an increase of sugar were observed in 3-day water-stressed red osier dogwood plants (Cornus stolonifera Michx.) when the frost hardiness increased from -3 to -6 C. As the frost hardiness increased to -11 C after 7 days of treatment, the starch continuously decreased, however, the proteins and RNAs increased with a continuous increase of sugar. Further water stress treatment had little effect on the changes of these chemicals. Control plants in short days showed similar gradual biochemical changes in patterns. From the results of frost hardiness increases, the pattern of biochemical changes, and the mechanism of the increased freezing resistance, it appears that the water stress and short days accomplished essentially the same physiological end(s) in inducing frost hardiness in red-osier dogwood.

Journal Article↗
PubMed1978

Environmental and Seasonal Factors Affecting the Frost-induced Stage of Cold Acclimation in Cornus stolonifera Michx.

Stem tissues of red-osier dogwood (Cornus stolonifera Michx.) acclimated from -3 C to -40 or -50 C in 8 to 10 weeks under a short photoperiod (9 hours) and controlled temperature conditions. During the summer months plants did not acclimate as well as at other times. The sequence of day/night temperature regimes which induced maximum acclimation was 20/15 C for 5 to 6 weeks; 15/5 C for 2 to 3 weeks; 15/5 C plus 1 hour of frost per day for 1 week. The duration of exposure to each temperature regime influenced the rate and intensity of frost-induced acclimation. Less than 5 weeks of warm temperature preconditioning at 20/15 C reduced subsequent frost-induced acclimation. The inductive influence of frost on cold acclimation was additive over 5 days of repeated exposure, but its effects after the first exposure(s) were not immediate-requiring 1 to 4 days of 15/5 C following the frost treatments for the expression of the frost-induced acclimation to be manifest. There was a 75% increase in rRNA following 3 days of frost exposure and plants in an O(2)-free atmosphere during frost exposure failed to acclimate. The results suggest that seasonal acclimation behavior was due to endogenous rhythms rather than developmental stage, and that the frost-induced phase of acclimation involves aerobic metabolic processes.

Journal Article↗
PubMed1979

Changes in Frost Hardiness of Stem Cortical Tissues of Cornus stolonifera Michx. after Recovery from Water Stress.

Moderate water stress increases frost hardiness in many woody plants but little attention has been given to changes in hardiness after recovery from water stress. Tests were carried out to examine how much water stress-induced frost hardiness remained when plants were rewatered under different day length regimes. Red osier dogwood plants (Cornus stolonifera Michx.) were water-stressed at normal growing temperatures in long day (LD) or short day (SD) conditions, exposed to 6 nights of freezing temperatures, and then returned to normal growing conditions with full water supply. Water-stressed plants gained an additional 8 to 10 C of hardiness. The amount of freeze-induced hardiness in both stressed and control plants was not significant (approximately 2 C) and was not affected by photoperiod. When plants were kept in or transferred to LD, they lost nearly all of their water stress-induced hardiness within 7 days after rewatering. Water-stressed plants in SD lost the least amount of hardiness (5 C) when rewatered. In dogwood, water stress is an effective way to increase hardiness temporarily, but the photoperiod has a large effect on the retention of the acquired hardiness.

Journal Article↗
PubMed1991

Effects of Mild Water Stress and Diurnal Changes in Temperature and Humidity on the Stable Oxygen and Hydrogen Isotopic Composition of Leaf Water in Cornus stolonifera L.

In this paper we make comparisons between the observed stable isotopic composition of leaf water and the predictions of the Craig-Gordon model of isotopic enrichment when plants (Cornus stolonifera L.) were exposed to natural, diurnal changes in temperature and humidity in a glasshouse. In addition, we determined the effects of mild water stress on the isotopic composition of leaf water. The model predicted different patterns of diurnal change for the oxygen and hydrogen isotopic composition of leaf water. The observed leaf water isotopic composition followed qualitatively similar patterns of diurnal change to those predicted by the model. At midday, however, the model always predicted a higher degree of heavy isotope enrichment than was actually observed in leaves. There was no effect of mild water stress on the hydrogen isotopic composition of leaf water. For the oxygen isotopic composition of leaf water, there was either no significant difference between control and water-stressed plants or the stressed plants had lower delta(18)O values, despite the enriched stem water isotopic composition observed for the stressed plants.

Journal Article↗
PubMed1989

Tannins of cornaceous plants. I. Cornusiins A, B and C, dimeric monomeric and trimeric hydrolyzable tannins from Cornus officinalis, and orientation of valoneoyl group in related tannins.

Cornusiin A (1), cornusiin B (2) and cornusiin C (3), new dimeric, monomeric and trimeric hydrolyzable tannins, were isolated from the fruits of Cornus officinalis (Cornaceae). Their structures, including the orientation of the valoneoyl group in 1 and 3, were established on the basis of chemical and spectroscopic data. 2,3-Di-O-galloyl-D-glucose (7), 1,2,3-tri-O-galloyl-beta-D-glucose, 1,2,6-tri-O-galloyl-beta-D-glucose, 1,2,3,6-tetra-O-galloyl-beta-D-glucose, gemin D (5), isoterchebin, tellimagrandin I (6) and tellimagrandin II were also isolated from the fruits. The orientation of the valoneoyl group in camptothin A (14) and that in camptothin B (15), which had been isolated from Camptotheca acuminata (Nyssaceae), were also determined based on that in 1.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Ellagic acid formation from galloylglucoses by a crude enzyme of Cornus capitata adventitious roots.

The aqueous extract of acetone powder, which had been prepared from Cornus capitata 'Mountain Moon' adventitious roots, cultured in MS medium with a high concentration of Cu2+(10 microM), showed strong oxidative activity toward galloylglucoses. A compound formed from galloyglucoses, such as 1,2,3,4,6-penta-O-galloyl-beta-D-glucose and tannic acid, by the reaction with the crude enzyme solution of the adventitious roots was isolated and characterized as ellagic acid by spectrometric analyses.

Chromatography, High Pressure Liquid↗
PubMed1997

[Damage-loss relationships and integrated control of 3rd instar larvae of Actias selene nigpoana Felder in planting area of Cornus officinalis Sieb. et Zucc].

In the present paper, the damage-loss model of Actias selene ningpoana to Cornus officinalis was tested and the results indicated that the yield loss rates obeyed the equation Y = 100 - EXP(4.6042 - 0.0315X). The economic threshold of the 2hd and 3rd instar larvae of A. selene nigpoana was then determined as 22 and 8 insects per tree respecitively. Suggestions for integrated control have been made based on the research of activities of A. selene ningpoana in the forest.

Animals↗
PubMed1997

Branch geometry in Cornus kousa (Cornaceae): computer simulations.

Computer simulations similar to actual trees were constructed using simple branching rules. Branch orientation with respect to the direction of gravity was a fundamental consideration. In Cornus kousa BUERG. ex HANCE, several types of branches develop from winter buds, varying from orthotropic shoots to plagiotropic ones. Based on actual observations and measurements of branching structures with a wide range of orientations, we made a flexible geometrical model consisting of five forking branches that varied in outgrowth depending on the direction of the shoot with respect to gravity. Repetition of the branching by computer generated a realistic tree pattern, which was close to the shape of a young C. kousa tree. Reproductive shoots seem to be under a branching rule that was a modification of vegetative branching, although the reproductive branch size was considerably smaller than the vegetative one, and reproductive branching was bifurcated instead of five-forked. We conclude that all branchings in orthotropic and plagiotropic shoots in the vegetative phase and shoots in the reproductive phase are formed under the same branching rule, but each has different parameter values.

Computer Simulation↗