Comparison analysis of metabolite profiling in seeds and bark of Ulmus parvifolia, a Chinese medicine species

Ulmus parvifolia (U. parvifolia) is a Chinese medicine plant whose bark and leaves are used in the treatment of some diseases such as inflammation, diarrhea and fever. However, metabolic signatures of seeds have not been studied. The seeds and bark of U. parvifolia collected at the seed ripening stage were used for metabolite profiling analysis through the untargeted metabolomics approach. A total of 2,578 and 2,207 metabolites, while 503 and 132 unique metabolites were identified in seeds and bark, respectively. Additionally, 574 differential metabolites (DEMs) were detected in the two different organs of U. parvifolia, which were grouped into 52 classes. Most kinds of metabolites classed into prenol lipids class. The relative content of flavonoids class was the highest. DEMs contained some bioactive compounds (e.g., flavonoids, terpene glycosides, triterpenoids, sesquiterpenoids) with antioxidant, anti-inflammatory, and anti-cancer activities. Most kinds of flavonoids and sesquiterpenes were up-regulated in seeds. There were more varieties of terpene glycosides and triterpenoids showing up-regulated in bark. The pathway enrichment was performed, while flavonoid biosynthesis, flavone and flavonol biosynthesis were worthy of attention. This study identified DEMs with pharmaceutical value between seeds and bark during seed maturation and offered a molecular basis for alternative or complementary use of seeds and bark of U. parvifolia as a Chinese medicinal material.

Chemical Constituents of Ulmus minor subsp. minor Fruits Used in the Italian Phytoalimurgic Tradition and Their Anti-inflammatory Activity Evaluation

The phytochemical investigation of Ulmus minor subsp. minor samaras EtOAc and n-BuOH extracts is reported in this work for the first time, resulting in the isolation and characterization of twenty compounds (1:  - 20: ) including one new flavan-3-ol (1: ), one new trihydroxy fatty acid (2: ), and two glycosylated flavonoids (6:  - 7: ) whose NMR data are not available in the literature. Structure elucidation of the isolated compounds was obtained by 1D and 2D NMR and HRESIMS data. Prior to further pharmacological investigations, the extracts (100 - 6.25 µg/mL) and compounds 1:  - 12: (50 - 5 µM) were tested for their influence on viability of a murine macrophage cell line (J774A.1). Subsequently, extracts and compounds that did not impede viability, were studied for their inhibitory effect on some mediators of inflammation in J774A.1 cells stimulated with lipopolysaccharide of Escherichia coli (LPS). The NO release and the expression of iNOS and COX-2 were then evaluated and both extracts (50 - 6.25 µg/mL) and compounds (20 - 5 µM) significantly inhibited NO release as well as iNOS and COX-2 expression in macrophages. These data highlight the anti-inflammatory properties of several isolated compounds from U. minor samaras supporting their possible alimentary use.

Cytology, transcriptomics, and mass spectrometry imaging reveal changes in late-maturation elm (Ulmus pumila) seeds

During seed maturation, the seed deposits storage compounds (starches, oils, and proteins), synthesizes defense compounds, produces a seed coat, initiates embryo dormancy, and becomes desiccated. During the late-maturation stage, seed storage compound contents and compositions change dramatically. Although maturation has been extensively studied in model species and crops, it remains less well characterized in woody perennial plants. In this study, we conducted morphological and cytological observations, transcriptome profiling, and chemical constituent analysis of elm (Ulmus pumila L.) seeds during the late-maturation stage. Light and electron microscopy revealed that closely packed yet discrete lipid bodies frequently surrounded the densely stained protein bodies, and the protein bodies became irregular or even partially disintegrated at the end of seed development. RNA-seq detected substantial transcriptome changes during the late-maturation stage, and pathway enrichment analysis showed that the differentially expressed genes were associated with phenylpropanoid biosynthesis, starch and sucrose metabolism, plant-pathogen interactions, and hormone signal transduction. Furthermore, we used mass spectrometry imaging to detect the relative intensity and spatial distribution of fatty acids, phospholipids, and waxes in elm seeds. Our findings provide a framework for understanding the changes in cytological features and chemical composition during the final stage of elm seed development, and a detailed reference for seed development in woody plants.

Response of the microbial community to phosphate-solubilizing bacterial inoculants on Ulmus chenmoui Cheng in Eastern China

Phosphate-solubilizing bacteria (PSB) have beneficial effects on plant health and soil composition. To date, studies of PSB in soil have largely been performed under field or greenhouse conditions. However, less is known about the impact of introducing indigenous PSB in the field, including their effects on the local microbial community. In this study, we conducted greenhouse and field experiments to explore the effects of the addition of indigenous PSB on the growth of Chenmou elm (Ulmus chenmoui) and on the diversity and composition of the bacterial community in the soil. We obtained four bacterial isolates with the highest phosphate-solubilizing activity: UC_1 (Pseudomonas sp.), UC_M (Klebsiella sp.), UC_J (Burkholderia sp.), and UC_3 (Chryseobacterium sp.). Sequencing on the Illumina MiSeq platform showed that the inoculated PSB did not become the dominant strains in the U. chenmoui rhizosphere. However, the soil bacterial community structure was altered by the addition of these PSB. The relative abundance of Chloroflexi decreased significantly in response to PSB application in all treatment groups, whereas the populations of several bacteria, including Proteobacteria and Bacteroidetes, increased. Network analysis indicated that Chloroflexi was the most strongly negatively correlated with Proteobacteria, whereas Proteobacteria was strongly positively correlated with Bacteroidetes. Our findings indicate that inoculation with PSB (UC_1, UC_M, UC_J, and UC_3) can improve the growth of U. chenmoui and regulate its rhizosphere microbial community. Therefore, inoculation with these bacterial strains could promote the efficient cultivation and production of high-quality plant materials.

Arabidopsis, tobacco, nightshade and elm take insect eggs as herbivore alarm and show similar transcriptomic alarm responses

Plants respond to insect eggs with transcriptional changes, resulting in enhanced defence against hatching larvae. However, it is unknown whether phylogenetically distant plant species show conserved transcriptomic responses to insect eggs and subsequent larval feeding. We used Generally Applicable Gene set Enrichment (GAGE) on gene ontology terms to answer this question and analysed transcriptome data from Arabidopsis thaliana, wild tobacco (Nicotiana attenuata), bittersweet nightshade (Solanum dulcamara) and elm trees (Ulmus minor) infested by different insect species. The different plant-insect species combinations showed considerable overlap in their transcriptomic responses to both eggs and larval feeding. Within these conformable responses across the plant-insect combinations, the responses to eggs and feeding were largely analogous, and about one-fifth of these analogous responses were further enhanced when egg deposition preceded larval feeding. This conserved transcriptomic response to eggs and larval feeding comprised gene sets related to several phytohormones and to the phenylpropanoid biosynthesis pathway, of which specific branches were activated in different plant-insect combinations. Since insect eggs and larval feeding activate conserved sets of biological processes in different plant species, we conclude that plants with different lifestyles share common transcriptomic alarm responses to insect eggs, which likely enhance their defence against hatching larvae.

The Reason for Growth Inhibition of Ulmus pumila 'Jinye': Lower Resistance and Abnormal Development of Chloroplasts Slow Down the Accumulation of Energy

Ulmus pumila 'Jinye', the colorful leaf mutant of Ulmus pumila L., is widely used in landscaping. In common with most leaf color mutants, U. pumila 'Jinye' exhibits growth inhibition. In this study, U. pumila L. and U. pumila 'Jinye' were used to elucidate the reasons for growth inhibition at the physiological, cellular microstructural, and transcriptional levels. The results showed that the pigment (chlorophyll a, chlorophyll b, and carotenoids) content of U. pumila L. was higher than that of U. pumila 'Jinye', whereas U. pumila 'Jinye' had a higher proportion of carotenoids, which may be the cause of the yellow leaves. Examination of the cell microstructure and RNA sequencing analysis showed that the leaf color and growth inhibition were mainly due to the following reasons: first, there were differences in the structure of the thylakoid grana layer. U. pumila L. has a normal chloroplast structure and clear thylakoid grana slice layer structure, with ordered and compact thylakoids. However, U. pumila 'Jinye' exhibited the grana lamella stacking failures and fewer thylakoid grana slice layers. As the pigment carrier and the key location for photosynthesis, the close stacking of thylakoid grana could combine more chlorophyll and promote efficient electron transfer promoting the photosynthesis reaction. In addition, U. pumila 'Jinye' had a lower capacity for light energy absorption, transformation, and transportation, carbon dioxide (CO₂) fixation, lipopolysaccharide biosynthesis, auxin synthesis, and protein transport. The genes related to respiration and starch consumption were higher than those of U. pumila L., which indicated less energy accumulation caused the growth inhibition of U. pumila 'Jinye'. Finally, compared with U. pumila 'Jinye', the transcription of genes related to stress resistance all showed an upward trend in U. pumila L. That is to say, U. pumila L. had a greater ability to resist adversity, which could maintain the stability of the intracellular environment and maintain normal progress of physiological metabolism. However, U. pumila 'Jinye' was more susceptible to changes in the external environment, which affected normal physiological metabolism. This study provides evidence for the main cause of growth inhibition in U. pumila 'Jinye', information for future cultivation, and information on the mutation mechanism for the breeding of colored leaf trees.

The effect of Tetraneura ulmi L. galling process on the activity of amino acid decarboxylases and the content of biogenic amines in Siberian elm tissues

Tetraneura ulmi (L.), a member of Eriosomatinae subfamily, is one of the gall-forming aphids occurring on elms. Sap-sucking behaviour of founding mothers results in the formation of new plant organs. This study documents the changes in the content of plant biogenic amines (putrescine, cadaverine, spermidine, tryptamine, spermine and histamine) and key enzymes of their biosynthesis: lysine decarboxylase (LDC), tyrosine decarboxylase and ornithine decarboxylase (ODC) in galls and other parts of Siberian elm (Ulmus pumila L.) leaves during the galling process. The direction and intensity of these changes for particular amines and enzymes were dependent on the stage of gall development and part of the galling leaf. Generally, the amine content tended to increase in gall tissues during the 1st and 2nd period of the galling process and decreased in later phases. LDC and ODC activities were markedly enhanced, especially in gall tissues at the initial stage of the galling process.

Arsenic forms and their combinations induce differences in phenolic accumulation in Ulmus laevis Pall

Total phenolics and the profile of phenolic acids and flavonoids were investigated in the roots and leaves of Ulmus laevis cultured on the medium with inorganic and organic arsenic - As(III), As(V) and DMA(V) at 0.06mM and their equimolar combinations. Further, the accumulation of salicylic acid (free and glucoside-bound) and lipid oxidation were assayed following a three-month long experiment. As treatment caused elevated production of phenolics, which was higher in photosynthetic tissue than in roots for all As forms and their combinations, and their overall content was correlated with the accumulation of organic As in roots and As(III) in leaves. The accumulation of organic As strongly induced shikimate-derived protocatechiuc acid in roots. Contrary to this, shikimate-derived phenolics (protocatechuic, gallic acids and 4-HBA) were suppressed in leaves, while the accumulation of C6C3 acids (caffeic, p-coumaric and chlorogenic) was stimulated by As(V) application. Surprisingly, these acids were not detected in the leaves of As(III)-treated plants, and mutually applied As(III) and DMA(V) reduced their content. DMA(V) negatively influenced the level of salicylic acid and its storage mechanism and this effect correlated with elevated MDA content in leaves. Quercetin accumulation was observed in both organs (mainly leaves) of DMA(V)-treated plants thereby proving its function in defensive response of Ulmus laevis to organic forms of As.

Bark and wood tissues of American elm exhibit distinct responses to Dutch elm disease

Tolerance to Dutch elm disease (DED) has been linked to the rapid and/or high induction of disease-responsive genes after infection with the fungus Ophiostoma novo-ulmi. Although the fungal infection by O. novo-ulmi primarily takes places in xylem vessels, it is still unclear how xylem contributes to the defense against DED. Taking advantage of the easy separation of wood and bark tissues in young American elm saplings, here we show that most disease-responsive genes exhibited higher expression in wood compared to bark tissues after fungal infection. On the other hand, the stress-related phytohormones were generally more abundant in the bark compared to wood tissues. However, only endogenous levels of jasmonates (JAs), but not salicylic acid (SA) and abscisic acid (ABA) increased in the inoculated tissues. This, along with the upregulation of JA-biosynthesis genes in inoculated bark and core tissues further suggest that phloem and xylem might contribute to the de novo biosynthesis of JA after fungal infection. The comparison between two tolerant elm varieties, 'Valley Forge' and 'Princeton,' also indicated that tolerance against DED might be mediated by different mechanisms in the xylem. The present study sheds some light on the amplitude and kinetics of defense responses produced in the xylem and phloem in response to DED.

Plant signals during beetle (Scolytus multistriatus) feeding in American elm (Ulmus americana Planch)

American Elms were devastated by an outbreak of Dutch Elm Disease is caused by the fungus Ophiostoma novo-ulmi Brasier that originated in Asia and arrived in the early 1900s. In spite of decades of study, the specific mechanisms and disease resistance in some trees is not well understood. the fungus is spread by several species of bark beetles in the genus Scolytus, during their dispersal and feeding. Our objective was to understand elm responses to beetle feeding in the absence of the fungus to identify potential resistance mechanisms. A colony of Scolytus multistriatus was established from wild-caught beetles and beetles were co-incubated with susceptible or resistant American elm varieties in a controlled environment chamber. Beetles burrowed into the auxillary meristems of the young elm shoots. The trees responded to the beetle damage by a series of spikes in the concentration of plant growth regulating compounds, melatonin, serotonin, and jasmonic acid. Spikes in melatonin and serotonin represented a 7,000-fold increase over resting levels. Spikes in jasmonic acid were about 10-fold higher than resting levels with one very large spike observed. Differences were noted between susceptible and resistant elms that provide new understanding of plant defenses.

Changes in the mitochondrial protein profile due to ROS eruption during ageing of elm (Ulmus pumila L.) seeds

Reactive oxygen species (ROS)-related mitochondrial dysfunction is considered to play a vital role in seed deterioration. However, the detailed mechanisms remain largely unknown. To address this, a comparison of mitochondrial proteomes was performed, and we identified several proteins that changed in abundance with accompanying ROS eruption and mitochondrial aggregation and diffusion. These are involved in mitochondrial metabolisms, stress resistance, maintenance of structure and intracellular transport during seed aging. Reduction of ROS content by the mitochondrial-specific scavenger MitoTEMPO suppressed these changes, whereas pre-treatment of seeds with methyl viologen (MV) had the opposite effect. Furthermore, voltage-dependent anion channels (VDAC) were found to increase both in abundance and carbonylation level, accompanied by increased cytochrome c (cyt c) release from mitochondria to cytosol, indicating the profound effect of ROS and VDAC on mitochondria-dependent cell death. Carbonylation detection revealed the specific target proteins of oxidative modification in mitochondria during ageing. Notably, membrane proteins accounted for a large proportion of these targets. An in vitro assay demonstrated that the oxidative modification was concomitant with a change of VDAC function and a loss of activity in malate dehydrogenase. Our data suggested that ROS eruption induced alteration and modification of specific mitochondrial proteins that may be involved in the process of mitochondrial deterioration, which eventually led to loss of seed viability.

Elm leaves 'warned' by insect egg deposition reduce survival of hatching larvae by a shift in their quantitative leaf metabolite pattern

Plants may take insect eggs on their leaves as a warning of future herbivory and intensify their defence against feeding larvae. Responsible agents are, however, largely unknown, and little knowledge is available on this phenomenon in perennial plants. We investigated how egg deposition affects the anti-herbivore defence of elm against the multivoltine elm leaf beetle. Prior egg deposition caused changes in the quality of feeding-damaged leaves that resulted in increased larval mortality and reduced reproductive capacity of the herbivore by harming especially female larvae. Chemical analyses of primary and secondary leaf metabolites in feeding-damaged, egg-free (F) and feeding-damaged, egg-deposited (EF)-leaves revealed only small differences in concentrations when comparing metabolites singly. However, a pattern-focused analysis showed clearly separable patterns of (F) and (EF)-leaves because of concentration differences in especially nitrogen and phenolics, of which robinin was consumed in greater amounts by larvae on (EF) than on (F)-leaves. Our study shows that insect egg deposition mediates a shift in the quantitative nutritional pattern of feeding-damaged leaves, and thus might limit the herbivore's population growth by reducing the number of especially female herbivores. This may be a strategy that pays off in a long run particularly in perennial plants against multivoltine herbivores.

Reactive oxygen species-provoked mitochondria-dependent cell death during ageing of elm (Ulmus pumila L.) seeds

Previous studies have shown that controlled deterioration treatment (CDT) induces programmed cell death in elm (Ulmus pumila L.) seeds, which undergo certain fundamental processes that are comparable to apoptosis in animals. In this study, the essential characteristics of mitochondrial physiology in elm seeds during CDT were identified by cellular ultrastructural analysis, whole-body optical imaging, Western blotting and semi-quantitative RT-PCR. The alteration in mitochondrial morphology was an early event during CDT, as indicated by progressive dynamic mitochondrial changes and rupture of the mitochondrial outer membrane; loss of mitochondrial transmembrane potential (Δψ(m)) ensued, and mitochondrial ATP levels decreased. The mitochondrial permeability transition pore inhibitor cyclosporine A effectively suppressed these changes during ageing. The in situ localization of production of reactive oxygen species (ROS), and evaluation of the expression of voltage-dependent anion-selective channel and cyclophilin D indicated that the levels of mitochondrial permeability transition pore components were positively correlated with ROS production, leading to an imbalance of the cellular redox potential and ultimately to programmed cell death. Pre-incubation with ascorbic acid slowed loss of mitochondrial Δψ(m), and decreased the effect of CDT on seed viability. However, there were no significant changes in multiple antioxidant elements or chaperones in the mitochondria during early stages of ageing. Our results indicate that CDT induces dynamic changes in mitochondrial physiology via increased ROS production, ultimately resulting in an irreversible loss of seed viability.

Adaptive significance of gall formation for a gall-inducing aphids on Japanese elm trees

Insect galls are abnormal plant tissues induced by external stimuli from parasitizing insects. It has been suggested that the stimuli include phytohormones such as auxin and cytokinins produced by the insects. In our study on the role of hormones in gall induction by the aphid Tetraneura nigriabdominalis, it was found that feedback regulation related to auxin and cytokinin activity is absent in gall tissues, even though the aphids contain higher concentrations of those phytohormones than do plant tissues. Moreover, jasmonic acid signaling appears to be compromised in gall tissue, and consequently, the production of volatile organic compounds, which are a typical defense response of host plants to herbivory, is diminished. These findings suggest that these traits of the gall tissue benefit aphids, because the gall tissue is highly sensitive to auxin and cytokinin, which induce and maintain it. The induced defenses against aphid feeding are also compromised. The abnormal responsiveness to phytohormones is regarded as a new type of extended phenotype of gall-inducing insects.

Inhibition of phenylpropanoid biosynthesis in Artemisia annua L.: a novel approach to reduce oxidative browning in plant tissue culture

Oxidative browning is a common and often severe problem in plant tissue culture systems caused by the accumulation and oxidation of phenolic compounds. The current study was conducted to investigate a novel preventative approach to address this problem by inhibiting the activity of the phenylalanine ammonia lyase enzyme (PAL), thereby reducing the biosynthesis of phenolic compounds. This was accomplished by incorporating 2-aminoindane-2-phosphonic acid (AIP), a competitive PAL inhibitor, into culture media of Artemisia annua as a model system. Addition of AIP into culture media resulted in significant reductions in visual tissue browning, a reduction in total phenol content, as well as absorbance and autoflourescence of tissue extracts. Reduced tissue browning was accompanied with a significant increase in growth on cytokinin based medium. Microscopic observations demonstrated that phenolic compounds accumulated in discrete cells and that these cells were more prevalent in brown tissue. These cells were highly plasmolyzed and often ruptured during examination, demonstrating a mechanism in which phenolics are released into media in this system. These data indicate that inhibiting phenylpropanoid biosynthesis with AIP is an effective approach to reduce tissue browning in A. annua. Additional experiments with Ulmus americana and Acer saccharum indicate this approach is effective in many species and it could have a wide application in systems where oxidative browning restricts the development of biotechnologies.

Spatial and temporal nature of reactive oxygen species production and programmed cell death in elm (Ulmus pumila L.) seeds during controlled deterioration

Seed deterioration is poorly understood and remains an active area for research. Seeds of elm (Ulmus pumila L.) were aged at 37 °C above water [controlled deterioration treatment (CDT)] for various lengths of time to assess programmed cell death (PCD) and reactive oxygen species (ROS) product in embryonic tissues during a 5 d period. The hallmarks of PCD were identified in the elm seeds during CDT including TUNEL experiments, DNA laddering, cytochrome c (cyt c) leakage and enzymatic activities. These analyses indicated that PCD occurred systematically and progressively in deteriorated elm seeds. Cyt c release and increase in caspase-3-like/DEVDase activity occurred during CDT, which could be suppressed by ascorbic acid (AsA) and caspase-3 inhibitor Ac-DEVD-CHO, respectively. In situ localization of ROS production indicated that the distinct spatial-temporal signature of ROS during CDT coincided with the changes in PCD hallmark features. Multiple antioxidant elements were activated during the first few days of CDT, but were subsequently depleted as PCD progressed. Taken together, our findings identify PCD as a key mechanism that occurs asymmetrically during elm seeds CDT and suggest an important role for PCD in seeds deterioration.

Neonicotinoid insecticide imidacloprid causes outbreaks of spider mites on elm trees in urban landscapes

Background

Attempts to eradicate alien arthropods often require pesticide applications. An effort to remove an alien beetle from Central Park in New York City, USA, resulted in widespread treatments of trees with the neonicotinoid insecticide imidacloprid. Imidacloprid's systemic activity and mode of entry via roots or trunk injections reduce risk of environmental contamination and limit exposure of non-target organisms to pesticide residues. However, unexpected outbreaks of a formerly innocuous herbivore, Tetranychus schoenei (Acari: Tetranychidae), followed imidacloprid applications to elms in Central Park. This undesirable outcome necessitated an assessment of imidacloprid's impact on communities of arthropods, its effects on predators, and enhancement of the performance of T. schoenei.

Methodology/Principal Findings

By sampling arthropods in elm canopies over three years in two locations, we document changes in the structure of communities following applications of imidacloprid. Differences in community structure were mostly attributable to increases in the abundance of T. schoenei on elms treated with imidacloprid. In laboratory experiments, predators of T. schoenei were poisoned through ingestion of prey exposed to imidacloprid. Imidacloprid's proclivity to elevate fecundity of T. schoenei also contributed to their elevated densities on treated elms.

Conclusions/Significance

This is the first study to report the effects of pesticide applications on the arthropod communities in urban landscapes and demonstrate that imidacloprid increases spider mite fecundity through a plant-mediated mechanism. Laboratory experiments provide evidence that imidacloprid debilitates insect predators of spider mites suggesting that relaxation of top-down regulation combined with enhanced reproduction promoted a non-target herbivore to pest status. With global commerce accelerating the incidence of arthropod invasions, prophylactic applications of pesticides play a major role in eradication attempts. Widespread use of neonicotinoid insecticides, however, can disrupt ecosystems tipping the ecological balance in favor of herbivores and creating pest outbreaks.

[Leaf nutrient contents and photosynthetic physiological characteristics of Ulmus pumila-Robinia pseudocacia mixed forests]

A field experiment was conducted to study the leaf N, P, and chlorophyll contents, photosynthetic gas exchange parameters, and chlorophyll fluorescence parameters in pure Ulmus pumila forest, pure Robinia pseudoacacia forest, and U. pumila-R. pseudoacacia mixed forests [1:1 (1B1C), 1:2 (1B2C), and 2:1 (2B1C)] in different growth periods. From May to September, the plant leaf N and P contents in pure and mixed forests all presented a decreasing trend. By the end of growth period, the leaf N content of U. pumila and the P content of R. pseudoacacia in 1B2C were obviously higher than those in pure forests. In the mixed forests, the chlorophyll content of U. pumila was obviously higher than that of R. pseudoacacia, and the chlorophyll content of U. pumila in 1B2C reached the highest in July. The photosynthetic rate (Pn) of U. pumila and R. pseudoacacia in mixed forests was higher than that in pure forests, and the Pn of R. pseudoacacia in 1B2C reached the highest (18.54 micromol x m(-2) x s(-1)) in July. The transpiration rate (Tr) and stomatal conductance (Gs) of R. pseudoacacia in mixed forests were higher than those in pure forests, and the Tr and Gs in mixed forests were in the order of 1B2C>1B1C>2B1C. In September, the quantum yield of PSII electron transport (phi(PS II)) of U. pumila in mixed forests was obviously higher than that in pure forest. The photochemical quenching coefficients (q(P)) of U. pumila and R. pseudoacacia in pure and mixed forests had no significant difference, but the non-photochemical quenching coefficient (NPQ) of the two tree species in 1B2C was significantly lower than that in corresponding pure forests. It was suggested that mixed planting U. pumila and R. pseudoacacia could significantly improve the leaf nutrient contents and photosynthetic capacity of the two tree species, and the optimum mixed ratio of U. pumila and R. pseudoacacia was 1:2.

Cryopreservation of the non-dormant orthodox seeds of Ulmus glabra

In order to evaluate the feasibility of cryopreservation of Wych elm ( Ulmus glabra Huds.) seeds, we evaluated the seeds sensitivity to extreme desiccation and/or the ultra-low temperature of liquid nitrogen (LN; -196 degrees C). We also determined the critical water content (WC) of desiccated seeds and the high-moisture freezing limit of seeds desiccated or moistened to various WCs and frozen for 24 h or up to two years in LN. Germination tests revealed no critical WC for seeds to 0.03 g H 2 O g -1 dry mass, g g -1 . Seeds tolerated freezing in LN within safe ranges of WC 0.03-0.21 g g -1 (nuts). Seeds desiccated to the safe WC and stored in LN for two years had similar germination as seeds stored at -3 degrees C for two years. Therefore, long-term cryopreservation of U. glabra seeds in gene banks is feasible.

Optimizing seed water content: relevance to storage stability and molecular mobility

This research was conducted to determine the optimum moisture content (MC) that gave maximum longevity to seeds. Three species were used to represent seeds with different dry matter reserves, which gives them different sorption properties: maize (Zea mays L.), elm (Ulmus pumila L.) and safflower (Carthamus tinctorius L.). The seeds of elm, safflower, and maize embryos with MC ranging from 0.00-0.15 g H2O/g dry weight (DW) were stored at 35 degrees C for different periods of time. The results showed that the optimum MC for seed and embryo storage varied between species (0.057 g H2O/g DW for maize embryos, 0.045 g H2O/g DW for elm, and 0.02 g H2O/g DW for safflower). Drying below this optimum MC increased the aging rate and there were detrimental effects of drying. The relative humidity corresponding to optimum MC in embryos of maize, elms and safflower was about 15%, 12% and 7% respectively, according to the lipid composition of the embryos. The data provided confirmatory evidence that molecular mobility (DeltaAzz) in elms, maize and safflower embryos was compatible with the optimum moisture content.

Nitrogen fixation by Elaeagnus angustifolia in the reclamation of degraded croplands of Central Asia

Extensive degradation of irrigated croplands, due to increasing soil salinity and depletion of soil nutrient stocks, is a major problem in Central Asia (CA), one of the largest irrigated areas in the world. To assess the potential for improving the productive capacity of degraded lands by afforestation, we examined N(2) fixation of Elaeagnus angustifolia L. in mixed plantations with non-fixing Populus euphratica Oliv. and Ulmus pumila L. Fixation of N(2) was quantified by the (15)N natural abundance technique based on both foliar and whole-plant sampling during five consecutive growing seasons. Despite elevated root-zone soil salinity (6-10 dS m(-1)) and deficiency in plant-available P (4-15 mg kg(-1)), N(2) fixation (%Ndfa) increased from an initial value of 20% to almost 100% over 5 years. Within each growing season, %Ndfa steadily increased and peaked in the fall. Annual N(2) fixation, determined using foliar delta(15)N, initially averaged 0.02 Mg ha(-1), peaked at 0.5 Mg ha(-1) during the next 2 years and thereafter stabilized at 0.3 Mg ha(-1). Estimates based on whole-plant delta(15)N were <10% lower than those based on foliar delta(15)N. The increase in plant-available soil N was significantly higher in E. angustifolia plots than in P. euphratica and U. pumila plots. Increases in the concentrations of organic C (19%), total N (21%) and plant-available P (74%) in the soil were significant irrespective of tree species. This improvement in soil fertility is further evidence that afforestation with mixed-species plantations can be a sustainable land use option for the degraded irrigated croplands in CA.

Hypolipidemic effect and antioxidant activity of glycoprotein isolated from Ulmus davidiana Nakai in Triton WR-1339-treated mouse

The glycoprotein isolated from Ulmus davidiana Nakai (UDN) (UDN glycoprotein) has a molecular weight of 116 kDa and consists of 78.65% carbohydrate content and 21.35% protein content. In the present study, we investigated the hypolipidemic effect of UDN glycoprotein on Triton WR-1339-induced mice. With pretreatment with UDN glycoprotein, the triacylglycerol (TAG), total cholesterol and low density lipoprotein-cholesterol (LDL-C) concentrations were significantly reduced, whereas high density lipoprotein-cholesterol (HDL-C) concentration was increased in the plasma of Triton WR-1339-induced mice. With respect to antioxidative activity, UDN glycoprotein significantly decreased the level of thiobarbituric acid reactive substances (TBARS) and improved activities of catalase and glutathione peroxidase (GPx), without an apparent change of superoxide dismutase (SOD) activity. Also UDN glycoprotein significantly increased nitric oxide (NO) production in Triton WR-1339-induced mice. These results indicate that UDN glycoprotein has a hypolipidemic effect, possesses antioxidant activity and has an ability to stimulate NO production. Thus, we speculate that UDN glycoprotein is an example of natural compound that lowers plasma lipid level together with having an antioxidant function in Triton WR-1339-induced mice.

The pathogen causing Dutch elm disease makes host trees attract insect vectors

Dutch elm disease is caused by the fungal pathogen Ophiostoma novo-ulmi which is transmitted by the native elm bark beetle, Hylurgopinus rufipes. We have found that four semiochemicals (the monoterpene (-)-beta-pinene and the sesquiterpenes (-)-alpha-cubebene, (+)-spiroaxa-5,7-diene and (+)-delta-cadinene) from diseased American elms, Ulmus americana, synergistically attract H. rufipes, and that sesquiterpene emission is upregulated in elm trees inoculated with O. novo-ulmi. The fungus thus manipulates host trees to enhance their apparency to foraging beetles, a strategy that increases the probability of transportation of the pathogen to new hosts.

Fourier transform-infrared spectroscopy as a new method for evaluating host resistance in the Dutch elm disease complex

Resistance of elms (Ulmus spp.) to the pathogenic fungus Ophiostoma novo-ulmi Brasier depends on chemical and anatomical factors that confine the spread of the pathogen in the vascular system of the host. This study focused on detecting chemical differences in 4-year-old Ulmus minor Mill. seedlings before and after inoculation with a virulent O. novo-ulmi isolate. According to symptom development over 60 days, the trees were divided into resistant (0-33% wilting) and susceptible (67-100% wilting) groups. Histochemical tests and Fourier transform-infrared (FT-IR) spectroscopy analysis were performed on transverse sections of 2-year-old twigs, 2 days before and 40 days after inoculation. Although histochemical tests did not clearly discriminate susceptible from resistant elms, chemical differences between resistant, susceptible and control trees were detected by FT-IR. The average spectrum for resistant tree samples had higher absorbance peaks than the spectra from the susceptible and control samples, indicating increased formation of lignin and suberin. The roles of lignin and suberin in the resistance of the elms against O. novo-ulmi and the usefulness and sensitivity of the FT-IR technique for analyzing metabolic changes caused by pathogens in plants are discussed.

Metabolic distinction of Ulmus minor xylem tissues after inoculation with Ophiostoma novo-ulmi

Dutch elm disease (DED) is the most devastating and widespread disease of elms. The pathogen, Ophiostoma novo-ulmi, spreads systemically causing xylem vessels blocking and cavitation, and ultimately resulting in the development of a wilt syndrome. Twig samples from susceptible and resistant Ulmus minor trees were harvested at 0, 5, 15, 30, 60, and 120 days post-inoculation (dpi) with O. novo-ulmi. Fourier transform-infrared (FT-IR) spectroscopy, in tandem with chemometrics, was used to monitor changes in wood chemistry as consequence of infection. Principal component analysis distinguished between spectra from inoculated and control elms, and from susceptible- and resistant-inoculated elms. By 30 dpi, infected xylem showed reduced relative levels of carbohydrates and enhanced relative levels of phenolic compounds, probably due to the degradation of cell wall polysaccharides by fungal enzymes and the synthesis of host defence compounds. On 15 dpi, samples from resistant-inoculated elms showed higher levels of starch than samples from susceptible-inoculated elms, suggesting that availability of starch reserves could affect the tree's capacity for defensive responses. The results showed the power of FT-IR spectroscopy for analysing changes in the major components of elm xylem as consequence of infection by DED, and its potential for detecting metabolic profiles related to host resistance.