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PubMed2004

[Effect of phosphorus stress on chlorophyll biosynthesis, photosynthesis and biomass partitioning pattern of Fraxinus mandchurica seedlings].

Phosphorus is essential to forest trees for their growth and development, because of its important role in many metabolic processes of trees. But, most part of phosphorus in soils of Northeastern China is immobile and unavailable, and thus, many forest trees often suffer from phosphorus stress which affects the biomass accumulation of forest trees. The aim of this study is to understand how the chlorophyll biosynthesis, photosynthesis and biomass partitioning of Fraxinus mandchurica seedlings response to phosphorus stress. Sand culture experiment showed that when the seedlings were under phosphorus stress, their 5-aminolevulinic acid (ALA) biosynthesis rate and porphobilinogen (PBG) synthase activity were reduced, but no significant changes in chlorophyll a and b, total chlorophyll and carotenoid contents were found. The nitrogen content in leaves and roots and the phosphorus content in all parts of seedlings were reduced under phosphorus stress, and the reduction of N content in leaves induced the decrease of maximum quantum efficiency of PS II (Fv/Fm) efficiency of PS II photochemistry (phi(PS II)), electron transport rate (E(TR)), and maximum photosynthesis rate (Amax). The effect of phosphorus stress on chlorophyll biosynthesis didn't affect photosynthesis. Under phosphorus stress, the total biomass decreased, but more biomass was partitioned into roots.

Biomass↗
PubMed2004

[Effect of different nitrogen supply on Fraxinus mandshurica seedling's biomass, N partitioning and their seasonal variation].

Nitrogen is one of the most important limiting nutrients for tree growth in temperature forest ecosystems. In this paper, the effects of nitrogen treatments on nitrogen partition and biomass allocation in roots and leaves of one-year-old Fraxinus mandshurica seedlings were studied during a five-month period. The plants were sand-cultured in pots supplied with various concentrations of N (1, 4, 8, 16 mmol x L(-1)). The results suggested that N supply could significantly increase the N concentration in roots and leaves. In the initial (June) and middle growth stage (July and August), the N concentration in leaves was over 9.40, 9.55 and 4.21 mg x g(-1) respectively, which was higher than that in roots, but in the latter growth stage (September), it was lower than that in roots. From June to September, the N content of whole plant increased markedly, and was 4 times more in September than in June. The N content in Ash seedlings varied with N supply. It increased by 5.5 times in 16 mmol x L(-1) N treatment, in comparing with 1 mmol x L(-1) N treatment in September. The N allocation also varied in leaf, stem, and root. The proportion of N allocation in leaf was the highest in June (43% in average), and the lowest in September (9% in average). The proportion of N allocation to root increased with plant growth, which was the highest in September (81% in average). Regardless N treatments and tree growth stages, the proportion of N allocation to root was the highest, followed by to leaf, and the lowest was to stem. These results provided the theoretical foundation for the further studies of nitrogen absorption and carbon allocation mechanism in root system of Manchurian ash.

Biomass↗
PubMed2004

[Effects of nitrogen stress on nutrient uptake by Fraxinus mandshurica seedlings and their biomass distribution].

Under environmental stresses, trees often change their morphological and physiological components to acquire the most limited resources. In northeastern forest region of China, the decomposition and mineralization of litters occur slowly due to low temperature, which often results in forest trees suffering from nutritional stress. With pot culture in greenhouse, this paper studied the effects of nitrogen stress on the physiological and morphological components of Fraxinus mandshurica seedlings. The results showed that under N stress, the net uptake rate of nitrogen and phosphate by the seedlings decreased, while their nitrogen and phosphate use efficiency were higher than those of the seedlings supplied with 8 mmol x L(-1) or 16 mmol x L(-1) of nitrogen during the early growth stage. When suffering from N stress, the leaf mass ratio of the seedlings reduced, with specific leaf area and root mass ratio increased. The relative growth rate increased with the increasing N concentrations supplied to the seedlings during the whole growth period. Under N stress, the net assimilation rate decreased, which resulted in the decrease of total biomass, and the root/shoot ratio was significantly higher than that of the seedlings supplied with 8 mmol x L(-1) or 16 mmol x L(-1) of nitrogen during the early growth stage. There was no significant difference during the late growth stage.

Biomass↗
PubMedDate not supplied

Comparison of cryopreservation techniques for long-term storage of ash (Fraxinus excelsior L.).

The main purpose of this study was to develop a cryopreservation protocol for ash and to highlight the importance of testing different clones and plant material of different ontogenetic states. In vitro-grown ash (Fraxinus excelsior L.) shoot tips were successfully cryopreserved following optimization of the PVS2-vitrification protocol. Pretreatment conditions were optimized and three cryopreservation techniques (encapsulation/dehydration, PVS2-vitrification and encapsulation-vitrification) were tested one after another. PVS2-vitrification proved to be the most suitable technique. In vitro-grown shoot tips of ash were successfully cryopreserved with a mean regrowth of 73% for juvenile clones and 67% for selected mature trees. The optimum preculture conditions and the initial protocol were: 10 days cold hardening, preculture for 2 days on medium with 0.8 M glycerol, incubation in 2 M glycerol solution for 20 min at 22 degrees C followed by PVS2 for 25 min at 0 degrees C on ice and direct immersion in liquid nitrogen. Warming was carried out in 43 degree C water for 1 min followed by 22 degree C water for 10 sec. The encapsulation/dehydration method was not successful for shoot tips of F. excelsior because the shoots were sensitive to osmotic dehydration. The encapsulation/vitrification method resulted in a mean regrowth of only 16%. PVS2 vitrification can now be used to store important ash germplasm of either juvenile or mature trees.

Cryopreservation↗
PubMed2005

Historical and contemporary mating patterns in remnant populations of the forest tree Fraxinus excelsior L.

Genetic variation at microsatellite markers was used to quantify genetic structure and mating behavior in a severely fragmented population of the wind-pollinated, wind-dispersed temperate tree Fraxinus excelsior in a deforested catchment in Scotland. Remnants maintain high levels of genetic diversity, comparable with those reported for continuous populations in southeastern Europe, and show low interpopulation differentiation (E = 0.080), indicating that historical gene exchange has not been limited (Nm = 3.48). We estimated from seeds collected from all trees producing fruits in three of five remnants that F. excelsior is predominantly outcrossing (t(m) = 0.971 +/- 0.028). Use of a neighborhood model approach to describe the relative contribution of local and long-distance pollen dispersal indicates that pollen gene flow into each of the three remnants is extensive (46-95%) and pollen dispersal has two components. The first is very localized and restricted to tens of meters around the mother trees. The second is a long-distance component with dispersal occurring over several kilometers. Effective dispersal distances, accounting for the distance and directionality to mother trees of sampled pollen donors, average 328 m and are greater than values reported for a continuous population. These results suggest that the opening of the landscape facilitates airborne pollen movement and may alleviate the expected detrimental genetic effects of fragmentation.

Biological Evolution↗
PubMed2006

[Distribution patterns of Fraxinus mandshurica root biomass, specific root length and root length density].

Employing soil core method, an investigation in Maoershan Experiment Station was made on the root biomass, specific root length (SRL), and root length density (RLD) of Fraxinus mandshurica plantation (17 yr) within a growth season in stand level. The results showed that the total root biomass was 1,637 g x m(-2), in which, living biomass accounted for 85%, and necrotic biomass was 15%. In the living biomass, coarse roots (5 approximately 30 mm in diameter) had the highest percentage (69.95 %), followed by fine roots (< 1 mm in diameter) (13.53 %), medium roots (2 approximately 5 mm in diameter) (7.21%), and small roots (1 approximately 2 mm in diameter) (9.31%). Among the four diameter classes, fine roots had a higher SRL (32.20 m x g(-1)), while coarse roots had a lower one (0.08 m x g(-1)). The total RLD in living biomass was 6,602.54 m x m(-2) in stand level, among which, fine root accounted for 92.43%, and the others was less than 8%. Fine root biomass and RLD had a positive correlation with soil available nitrogen, while no significant correlation was found between SRL and soil available nitrogen.

Biomass↗
PubMed2006

[Root decomposition and nutrient release of Fraxinus manshurica and Larix gmelinli plantations].

A two-year buried bag experiment with different sizes of Fraxinus mandshurica and Larix gmelinii roots showed that the coarse (5 to approximately 10 mm), medium (2 to approximately 5 mm) and fine ( <2 mm) roots of F. mandshurica had an annual decomposition coefficient of 0.3649, 0.4381 and 0.2720, while those of L. gmelinii had the coefficient of 0.1967, 0.1955 and 0.2464, respectively. During root decomposition, large amounts of carbon and nutrients released. After buried into soil for 150 days, more than 90% of soluble sugar in all sizes of the two species roots was released, and about 40%, 71% and 95% of potassium was released from the coarse and medium, and fine roots of F. mandshurica, and all sizes of L. gmelinii roots, respectively. In the second year of the experiment, about 50% of nitrogen and 40% of phosphorus were released from the coarse and medium roots of the two species, and 60% of nitrogen and phosphorus were released from their fine roots. In the study of forest ecosystem's carbon and nutrient cycles, root decomposition shouldn't be ignored.

Carbon↗
PubMed2000

The impact of season of harvest and duration of pre-measurement storage impact hydraulic conductance of stem samples for Acer rubrum L. x saccharinum L. and Fraxinus americana L.

The influence of pre-measurement storage length and season of harvest of stem segment samples on hydraulic conductance and percentage embolism was determined for two tree species because no published guidelines exist concerning storage. Stem sections from Fraxinus americana L. 'Autumn Applause' (white ash) and Acer rubrum L. x saccharinum L. 'Autumn Blaze' (hybrid red maple) were collected from well-established trees in fall 1995 (October), spring 1996 (April), and summer 1996 (July). Ends of stem sections collected in the fall were either covered with wax or left exposed. Entire sections from all dates were placed in closed plastic bags to prevent desiccation during transport and subsequent storage. Stem sections were either analyzed immediately (0 storage) or held at 2 degrees C for 2 or 4 days. Hydraulic conductance before embolisms were cleared with positive pressure (initial k(h)), hydraulic conductance after embolisms were cleared (maximum k(h)), and percentage embolism were similar for all pre-embolism measurement storage lengths within each of the three seasonal sampling periods for hybrid red maple and spring- and summer-collected white ash. Fall-collected white ash samples with 0 storage had higher initial k(h), and percentage embolism increased if samples were stored. Embolism was greatest for summer-collected samples and lowest for spring-collected samples for hybrid red maple, but values were similar for white ash. Stem covering did not influence measured parameters. Our data indicate that hybrid red maple stem segments can be stored without significant loss of hydraulic conductance for up to 4 days, but white ash should not be stored in the fall. Unless maximum levels of native embolism have been reached, as determined from laboratory analysis, stem segments of species on which storage data are not available should be processed as soon as possible.

Journal Article↗
PubMed2001

Fraxinus ornus L.

The literature on the chemical constituents and the biological activity of Fraxinus ornus bark, leaves and flowers has been reviewed. Chemical studies show the presence of many compounds belonging mainly to the groups of hydroxycoumarins, secoiridoid glucosides, phenylethanoids and flavonoids. Biological studies reveal significant antimicrobial, antioxidative, photodynamic damage prevention, wound healing, anti-inflammatory, immunomodulatory and antiviral activities, and support the use of the bark in the folk medicine.

Anti-Infective Agents↗
PubMed2000

Ash (Fraxinus excelsior)-pollen allergy in central Europe: specific role of pollen panallergens and the major allergen of ash pollen, Fra e 1.

BACKGROUND: The role of ash (Fraxinus excelsior) pollen as a cause of spring pollinosis in central Europe has received little attention. It is not clear whether ash pollen is a primary cause of sensitization or whether it is implicated through cross-sensitization to other pollens. METHODS: Over a 22-month period, ash pollen was included in a screening series for inhalant allergies. Pollen data were documented from 1976 through 1999. The frequency of IgE-binding to the ash-specific allergen Fra e 1 and pollen panallergens, respectively, was compared by Western blot between mono- (n = 6), oligo- (n = 16), and polysensitized (n=25) patients. RESULTS: Of 5,416 consecutive patients sensitized to any pollen, 920 (17.6%) had a positive skin prick test to ash. Total pollen counts varied extensively between years (229-5,351) as did peak concentrations (23-837 grains/m3/24 h). Western blotting revealed Fra e 1 sensitization in 100% of monosensitized, 93% of oligosensitized, but only 44% of polysensitized patients. IgE against profilins (Fra e 2), Ca-binding proteins (Fra e 3), and carbohydrate epitopes in the three groups was found in 0/0/17%, 0/19/31%, and 32/72/60%, respectively. At least 50% of sera from patients with Fra e 1 sensitization did not bind with the protein in Western blots under reducing conditions. CONCLUSIONS: Ash pollen should be considered a relevant factor and distinct entity in spring pollinosis. In all, only 20% of positive skin tests to ash appear to result from cross-sensitization to pollen panallergens.

Allergens↗
PubMed2002

Mating system and population genetic structure of an androdioecious tree, Fraxinus lanuginosa Koidz. (Oleaceae) in northern Japan.

Models for the maintenance of androdioecy have suggested that selfing of hermaphrodites decreases the frequency of males in a population (the "male frequency"). To test this hypothesis, we used electrophoretic allozyme methods to study the mating system and population genetics of an androdioecious tree, Fraxinus lanuginosa, which exhibits large variations in male frequency among subpopulations in central Hokkaido (northern Japan). We estimated the outcrossing rates by using seeds assayed at three polymorphic loci, and found that the multilocus outcrossing rate (t(m)) increased with increasing male frequency (q) (t(m) = 0.69 to 0.99, q = 0.11 to 0.59). Fixation indices (F(j)) estimated from these t(m) values ranged from 0.006 to 0.185, and were significantly greater than zero in plots with a low male frequency (q or = 0.47). However, fixation indices at the late life stage (F(a)) were not significantly different from zero at five loci (F(a) = 0.056 to 0.101, q = 0.11 to 0.61), and the F(a) values were lower than the F(j) values in several of the plots where both values were measured. These results indicate that inbreeding depression substantially decreases the proportion of selfed progeny in partially self-fertilising subpopulations. A theoretical model for the maintenance of androdioecy showed expected male frequencies significantly lower than the observed values in plots with high male frequency (q = 0.59 to 0.61), although the differences between the expected and observed values of male frequencies were not significant in plots with intermediate or low male-frequencies (q = 0.11 to 0.47). In this paper, the factors are discussed that affect variations in the male frequency among subpopulations of F. lanuginosa based on these findings.

Animals↗
PubMed2000

Biochemical model reactions indicative of inflammatory processes. Activities of extracts from Fraxinus excelsior and Populus tremula.

All processes of oxygen activation include very reactive intermediates. Therefore, aerobic cells must cope with--and to some extent also adapt to--oxidative stress provoked for example by infections or intoxications, where these reactive intermediates accumulate. All inflammatory processes include such oxygen activating processes where reactive oxygen species (ROS) are produced. Dependent on the strength of these impact(s), several symptoms indicate the deviation from normal, steady-state metabolism. Intrinsic radical scavenging processes or compounds administered with food thus have to warrant metabolic control within certain limits. Antioxidants which in many cases are free radical scavengers or quenchers of activated states comprise a vast number of classes of organic molecules including phenolics as the most prominent ones. In this publication the activities of extracts from Fraxinus excelsior, Populus tremula and Solidago virgaurea as components of the drug Phytodolor and their mechanisms of protection from oxidative damage are summarized. In addition, new results on tyrosine nitration, a process characteristic for sites of inflammation, and its inhibition by these plant extracts, is reported.

Animals↗
PubMed1995

Additional secoiridoid glucosides from Fraxinus uhdei.

A new secoiridoid named uhdenoside (1) has been isolated from the leaves of Fraxinus uhdei (Oleaceae) along with ligustroside (3) and 10-hydroxyoleuropein (4). The structure of 1 was determined by spectral and chemical methods.

China↗
PubMed1999

In vitro inducible nitric oxide synthesis inhibitory active constituents from Fraxinus rhynchophylla.

Bioassay-guided fractionation of an H2O extract of the barks of Fraxinus rhynchophylla has furnished two inducible nitric oxide synthase (iNOS) inhibitory compounds, ferulaldehyde (1) and scopoletin (3) together with a coumarin, fraxidin (2). Compounds 1 and 3 showed inhibition of nitric oxide (NO) synthesis in a dose-dependent manner by murine macrophage-like RAW 264.7 cells stimulated with interferon-gamma (IFN-gamma) plus lipopolysaccharide (LPS). The inhibition of NO synthesis of 1 was reflected in the decreased amount of iNOS protein, as determined by Western blotting.

Acrolein↗
PubMed1995

Systematic variation in xylem hydraulic capacity within the crown of white ash (Fraxinus americana).

A 7-m tall white ash tree (Fraxinus americana Marsh.) was dissected, and hydraulic parameters of the xylem were determined by inducing a steady-state flow of water through the stem segments and monitoring volume and velocity flow rates. Leaf-specific conductivity (LSC) was highest in the main stem and lowest in some of the leaf-bearing lateral shoots. The LSC was higher in the main stem than in branches and higher in primary than in secondary branch axes. Terminal leaf-bearing shoots were larger and had a significantly greater mean LSC than subjacent lateral shoots. A significant reduction in LSC was associated with the transition between 1- and 2-year-old growth. In branches of the same age, there was a close correspondence among LSC, branch position and branch size. The average LSC of leaf-bearing shoots from south-facing branches was 43% greater than that of shoots from north-facing branches. Within-crown variation in LSC was associated with variation in velocity flow rate (V). By contrast, the ratio of potentially functional xylem area to supported leaf area (A(pf)/A(l)) was relatively stable throughout the crown. Stratification of stems by Strahler order accounted for approximately 70% of the total variation in LSC. These results suggest that (1) there exists a systematic pattern of variation in LSC distribution within the crown of white ash, (2) within-crown variability in LSC is primarily the result of variation in mean vessel diameter, and (3) there is a physiological linkage between LSC and crown morphology that is maintained through a positive feedback mechanism during branch ontogeny.

Journal Article↗
PubMed1995

Physiological, morphological and anatomical responses of Fraxinus mandshurica seedlings to flooding.

Two-year-old Fraxinus mandshurica Rupr. var. japonica Maxim. seedlings were flooded to 8 cm above soil level for 70 days. The flooding treatment altered the growth, morphology, stem anatomy and ethylene production of the seedlings. Although flooding did not affect height growth, it stimulated diameter growth of the submerged stems by increasing both the number and size of wood fibers produced; however, the thickness of the cell walls of the wood fibers was reduced by flooding. In response to the flooding treatment, the seedlings formed abundant hyperhydric tissues, originating from the vicinity of lenticels on the surface of the flooded stems, and adventitious roots, which grew through the hyperhydric tissues. Aerenchyma tissues were observed in the bark of the adventitious roots. The flooding treatment did not affect dry weight increment of leaves and stems, but it reduced the total dry weight increment of the root system even though it promoted adventitious root formation. Flooding also enhanced ethylene production in the submerged portions of stems. The potential roles of flood-induced ethylene in cambial growth and adventitious root formation in flooded plants are discussed.

Journal Article↗
PubMed1997

Gas exchange and water relations of Fraxinus americana affected by flurprimidol.

Effects of flurprimidol on plant water relations and leaf gas exchange were investigated in one-year-old white ash (Fraxinus americana L.) seedlings subjected to soil water deficits. Flurprimidol (20 mg kg(-1) of soil equivalent) was applied to the soil surface of pot-grown seedlings after shoot growth was completed. Two months after flurprimidol application, water was withheld from one-half of the seedlings. Leaf water relations and gas exchange parameters were measured 5, 7, 10, 14, 18 and 22 days after withholding water. Under both irrigated and nonirrigated conditions, flurprimidol treatment resulted in reduced net CO(2) assimilation rate and transpirational water loss of seedlings as a result of decreased stomatal conductance. Consequently, flurprimidol-treated seedlings had higher leaf water potential and relative water content than untreated seedlings. Nonirrigated flurprimidol-treated seedlings also had greater turgor and sap osmolality and lower osmotic potential at full turgor than seedlings in the other treatments, indicating that flurprimidol increased osmotic adjustment. Under water-stress conditions, water use efficiency was lower and gas exchange efficiency was higher in flurprimidol-treated seedlings than in untreated seedlings, suggesting that flurprimidol treatment enhances survival of plants subjected to soil water deficits.

Journal Article↗