Other Plants (other + plant)

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  • other plant species

  • Selected Abstracts

    Pittosporum undulatum Vent. grown in Portugal: secretory structures, seasonal variation and enantiomeric composition of its essential oil

    Nicolau J. Ferreira
    Abstract Aerial parts of Pittosporum undulatum were collected fortnightly for 1 year at the Parque de Saúde de Lisboa. Collective samples of two populations were investigated, i.e. from pruned and non-pruned trees, and in addition samples from one pruned and one non-pruned individual. An SEM study of the aerial parts showed the presence of non-glandular T-shaped trichomes, and capitate trichomes with an elongated stalk and two to four round-shaped cells on the top. Numerous canals were seen at the level of the capsule wall as well as in the leaves and stems. Essential oil samples were isolated from the (deep-frozen) aerial parts by hydrodistillation to estimate the oil yields, and by distillation,extraction to determine their percentage composition, and analysed by GC and GC,MS. Monoterpenes (59,97%) were dominant in all oils, sabinene (5,58%), limonene (2,37%) and terpinen-4-ol (4,27%) being the major components, although in different relative amounts during the year of collection. Benzyl benzoate (8%) and benzyl salicylate (10%) attained high relative amounts in the oils from fully developed flowers, whereas in the oils from the other plant parts their relative amounts did not exceed 1%. The enantiomeric ratio of sabinene, limonene and terpinen-4-ol was investigated in the leaf, flower and capsule oils, showing dominance of the (+)-forms and homogeneity between all the oil samples. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Effects of nest-site characteristics and parental activity on cowbird parasitism and nest predation in Brown-and-yellow Marshbirds

    Walter S. Svagelj
    ABSTRACT Nest-site selection and nest defense are strategies for reducing the costs of brood parasitism and nest predation, two selective forces that can influence avian nesting success and fitness. During 2001,2002, we analyzed the effect of nest-site characteristics, nesting pattern, and parental activity on nest predation and brood parasitism by cowbirds (Molothrus spp.) in a population of Brown-and-yellow Marshbirds (Pseudoleistes virescens) in the Buenos Aires province, Argentina. We examined the possible effects of nest detectability, nest accessibility, and nest defense on rates of parasitism and nest predation. We also compared rates of parasitism and nest predation and nest survival time of marshbird nests during the egg stage (active nests) with those of the same nests artificially baited with passerine eggs after young fledged or nests failed (experimental nests). Most nests (45 of 48, or 94%) found during the building or laying stages were parasitized, and 79% suffered at least one egg-predation event. Cowbirds were responsible for most egg predation, with 82 of 107 (77%) egg-predation events corresponding to eggs punctured by cowbirds. Nests built in thistles had higher rates of parasitism and egg predation than nests in other plant, probably because cowbirds were most active in the area where thistles were almost the only available nesting substrate. Parasitism rates also tended to increase as the distance to conspecific nests increased, possibly due to cooperative mobbing and parental defense by marshbirds. The proportion of nests discovered by cowbirds was higher for active (95%) than for experimental (29%) nests, suggesting that cowbirds used host parental activity to locate nests. Despite active nest defense, parental activity did not affect either predation rates or nest-survival time. Thus, although nest defense by Brown-and-yellow Marshbirds appears to be based on cooperative group defense, such behavior did not reduce the impact of brood parasites and predators. RESUMEN La selección del sitio de nidificación y defensa del nido son estrategias que reducen los costos del parasitismo de cría y predación de nidos, dos fuerzas selectivas que pueden afectar el éxito reproductivo y la eficacia biológica de las aves. Durante 2001,2002, analizamos el efecto de las características del sitio de nidificación, patrón de nidificación, y actividad parental en la predación de nidos y parasitismo de cría por tordos (Molothrus spp.) en una población de Pseudoleistes virescens en la provincia de Buenos Aires, Argentina. Examinamos los posibles efectos de la detectabilidad, accesibilidad y defensa del nido en las tasas de parasitismo y depredación de nidos. Asimismo, se compararon las tasas de parasitismo, depredación, y tiempo de supervivencia de los nidos entre los estadios de huevo (nidos activos) con los de los mismos nidos cebados artificialmente con huevos de passerinos (nidos experimentales). La mayoría de los nidos (45 de 48, o 94%) hallados durante los estadios de construcción y puesta fueron parasitados, donde el 79% de los nidos sufrieron al menos un evento de predación de huevos. Los tordos fueron responsables de la mayoría de los eventos de predación de huevos, donde 82 de 107 (77%) eventos de predación correspondieron a huevos picados por tordos. Los nidos construidos en cardos tuvieron tasas de predación y parasitismo más altas que las correspondientes a nidos construidos en otros sustratos, probablemente debido a que los tordos exhiben una mayor actividad en el área donde los cardos son el único sustrato de nidificación disponible. La tasa de parasitismo mostró una tendencia a crecer con la distancia al nido más próximo, probablemente debido a la defensa parental y los despliegues de defensa comunales de Pseudoleistes virescens. La proporción de nidos descubiertos por tordos fue mayor para nidos activos (95%) que para nidos experimentales (29%), lo cual sugiere que los tordos utilizaron la actividad parental para detectar los nidos. A pesar de la activa defensa del nido, descubrimos que la actividad parental no afectó ni la tasa de predación ni el tiempo de supervivencia de los nidos. De esta forma, a pesar de que la defensa del nido en Pseudoleistes virescens aparenta estar basada en la defensa cooperativa grupal, tal comportamiento no redujo el impacto de los parásitos de cría o predadores de nidos. [source]

    Selective bio-availability of phenolic acids from Scottish strawberries

    Wendy R. Russell
    Abstract Scottish strawberries were found to be a rich source of phenolic acids, namely benzoic (1287.95 ± 279.98 mg/kg) and cinnamic (1159.40 ± 233.96 mg/kg) acids, both free and attached to other plant components. Studies suggest a chemopreventative role for such compounds in several major clinical conditions, but the anticipated benefits are likely to be affected by their bio-availability and metabolic fate. In this pilot study, strawberries (750 g) was consumed by four healthy human volunteers (32 ± 6 years). Only the benzoic acids were detected in the plasma. Of these, the major free (gentisic, protocatechuic and p -hydroxybenzoic acid) and conjugated (syringic acid) benzoic acids were 26,27% recovered in the urine within 5 h. Cinnamic acids were completely undetected in plasma and only trace amounts were found in the urine. Since, the cinnamic acids escaped absorption early in the gastrointestinal tract, their release and/or metabolism is dependant on the host colonic microbiota. Results indicate that there is a high degree of selective absorption of strawberry phenolic acids into the systemic circulation. If selective absorption of phenolic acids is observed with consumption of other plant-based foods, this is likely to have implications for the bioactive role of these compounds in chronic disease prevention. [source]

    Molecular and histochemical characterisation of two distinct poplar Melampsora leaf rust pathosystems

    PLANT BIOLOGY, Issue 2 2010
    B. Boyle
    Abstract In this study, we compared interactions of two Melampsora foliar rust species with poplar, which resulted in either limited or abundant pathogen proliferation. In the pathosystem exhibiting limited pathogen growth, a defence response was observed after invasion of poplar leaf tissues by the biotroph, with late and clear production of reactive oxygen species (ROS) and other products. Characterisation of the histological, biochemical and transcriptional events occurring in both pathosystems showed striking similarity with components of plant defence reactions observed during qualitative resistance. Key components associated with development of an active defence response, such as up-regulation of pathogenesis-related (PR) genes, were observed during infection. Moreover, the time course and strength of gene induction appear to be critical determinants for the outcome of the tree,pathogen interaction. This work provides basic biochemical characterisation and expression data for the study of so-called partial resistance in the poplar,rust pathosystem, which is also applicable to other plant,pathogen interactions resulting in quantitative disease resistance. [source]


    Michael F. Fay
    Summary. Plants that parasitise other plants have been among the most difficult plant groups to fit into classification systems due to their modified biology and their often highly reduced morphology. They are now considered to be found in about 16 families of flowering plants. Here we summarise current ideas about their relationships and provide information about their characteristics and utilisation. A major consequence of the revised classification of Orobanchaceae and related families has been the break-up of the traditional Scrophulariaceae, and here we summarise the new classification, focusing on genera of horticultural interest. [source]

    How do plants know when other plants are flowering?

    ECOLOGY LETTERS, Issue 11 2009
    Resource depletion, mast-seeding in a perennial wildflower, pollen limitation
    Abstract Mast-seeding is the synchronous and periodic reproduction by plant populations. This phenomenon has been widely studied from a community-level perspective, but we know extremely little about how plants are able to synchronize reproduction. Here, we present the first experimental test of proximate mechanisms of mast-seeding, by preventing reproduction in an iteroparous, mast-seeding wildflower. Through a series of experiments, we show that mobile carbohydrate stores (NSC) control alternate-year flowering by individual plants; seed set depletes NSC which prevents flowering the following year. Plants are synchronized by density-dependent pollen limitation; when plants flower asynchronously, they set fewer seeds, which prevents NSC depletion. Therefore, these individual plants flower in subsequent years and become synchronized. Because mast-seeding is a consequence of physiological controls of reproduction, differences in plant resource acquisition and allocation could dramatically change patterns of seed production, and changes in plant consumers and pollinators could change selection on physiological and developmental pathways. [source]

    Uptake and translocation of p,p,-dichlorodiphenyldichloroethylene supplied in hydroponics solution to Cucurbita

    Martin P. N. Gent
    Abstract Field studies show shoots of zucchini (Cucurbita pepo L.) accumulate various hydrophobic contaminants from soil, although many other plants do not, including cucumber (Cucumis sativus L.). To investigate the mechanism for this uptake, we presented p,p,-dichlorodiphenyldichloroethylene (DDE) to these two species in hydroponics solution. A mixture of DDE bound to TenaxÔ beads stirred with a solution of water passing through a reservoir provided a flowing solution containing DDE at approximately 2 ,g/L for many weeks duration. Approximately 90% of the DDE supplied in solution was adsorbed on the roots of both cucumber and zucchini. Less than 10% of the sorbed DDE was released subsequently when clean solution flowed past these contaminated roots for 9 d. The shoots of both species accumulated DDE, but the fraction that moved from the roots to the shoot in zucchini, ranging from 6 to 27% in various trials, was 10-fold greater than that in cucumber, 0.7 to 2%. The gradient in DDE concentration in zucchini tissues was in the order root > stem > petiole > leaf blade, indicating the movement was through the xylem in the transpiration stream. Some DDE in leaf blades might have been absorbed from the air, because the concentration in this tissue varied less with time, position in trough, or species, than did DDE in stems and petioles. The remarkable ability of zucchini to translocate DDE could not be attributed to differences in tissue composition, growth rate, distribution of weight among plant parts, or in the leaf area and rate of transpiration of water from leaves. Some other factor enables efficient translocation of hydrophobic organic contaminants in the xylem of zucchini. [source]

    Geranyl acetate esterase is commonly present but linalyl acetate esterase occurrence is highly limited in plants

    Neelam S. Sangwan
    Abstract Esterases are a group of hydrolytic enzymes that split ester bonds by addition of water and are ubiquitously present in diverse biosystems. Although animal esterases are well studied and are catalytically and functionally classified into different groups, plant enzymes have been viewed rather generally and are casually recruited as biochemical markers in morphogenesis, genetic characterization of plants, etc., without functional emphasis. Some volatile oil plants constitutively synthesize their characteristic monoterpene esters, geranyl acetate and linalyl acetate being the most common among them in the acyclic monoterpene class, whereas other plants also synthesize some volatile hemi- to sesquiterpene esters but inductively under certain ecological situations, such as herbivory, wounding, etc. This study concerns screening relative distribution of geranyl acetate esterase and linalyl aceate esterase activities in selected medicinal and aromatic plants, and reveals that in plants geranyl acetate (a primary alcohol ester) esterase is commonly present, while linalyl acetate (a tertiary alcohol ester) esterase seems to be highly limited to those plants (e.g. Lippia alba, Mentha citrata) that biosynthesize the tertiary monoterpene alcohol linalool and its ester. Such contrasting distribution of the two discrete types of esterases has been discussed in light of scenario of their microbial counterparts and structure,function relationships established thereon. This study makes it obvious that the GGG(A)-X motif esterases (acting on tertiary alcohol esters) are rare entities in plants too, similar to microbes. Furthermore, their presence in some volatile oil plants renders such plants novel phytoresources of the GGGX/GGAX motif hydrolases. Detailed characterization of the motif-specific plant esterases would have an immense impact on understanding of their structure,function relationships in plants. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Moss beneath a leafless larch canopy: influence on water and energy balances in the southern mountainous taiga of eastern Siberia

    Kazuyoshi Suzuki
    Abstract The southern mountainous taiga of eastern Siberia has a sparse larch canopy and an understory dominated by a thick moss layer. The physiology of moss is very different from that of other plants, as mosses lack roots and vascular systems and take up water directly. During May 2002, we conducted hydrological and meteorological measurements in the taiga of eastern Siberia to investigate the role of understory moss on water and energy balances within a leafless larch forest. We found that below-leafless canopy net all-wave radiation partitions into 39% latent heat flux and 39% sensible heat flux, while the mean daily Bowen ratio is about 1. Ground heat flux on the moss surface is also an important factor, as it comprises 22% of net all-wave radiation. Evaporation from moss beneath the leafless canopy was 24 mm during the 1-month observation period, representing 23% of the water flux into the larch forest. This finding implies that moss intercepted 23% of the water flux into the larch forest. In addition, evaporation from the moss understory during May 2002 comprised 22% of total evapotranspiration previously estimated above the canopy (April,October 2001). We conclude that moss is an important component of the water and energy balance in larch forests in the taiga region. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Resource and non-resource root competition effects of grasses on early- versus late-successional trees

    JOURNAL OF ECOLOGY, Issue 3 2009
    Christian Messier
    Summary 1This study assessed the effects of resource (i.e. nutrients) and non-resource (i.e. interference for space) competition from fine roots of competing grasses on the growth, morphology and architecture of fine roots of four tree species of varying successional status: Populus deltoides ¥ P. balsamifera (a hybrid), Betula papyrifera, Acer saccharum and Fraxinus americana. We tested the general hypothesis that tree fine-roots are affected by both below-ground resource and non-resource competition from non-self plants, and the more specific hypothesis that this effect is stronger in early-successional tree species. 2The experiment was conducted in split-containers where half of the roots of tree seedlings experienced either below-ground resource competition or non-resource competition, or both, by grasses while the other half experienced no competition. 3The late-successional tree species A. saccharum and F. americana were mostly affected by resource competition, whereas the early-successional P. deltoides¥balsamifera and B. papyrifera were strongly affected by both resource and non-resource competition. Non-resource competition reduced fine-root growth, root branching over root length (a measure of root architecture) and specific root length (a measure of root morphology) of both early-successional species. 4Synthesis. This study suggests that early-successional tree species have been selected for root avoidance or segregation and late-successional tree species for root tolerance of competition as mechanisms to improve below-ground resource uptake in their particular environments. It also contradicts recent studies showing perennial and annual grasses tend to overproduce roots in the presence of non-self conspecific plants. Woody plants, required to grow and develop for long periods in the presence of other plants, may react differently to non-self root competition than perennial or annual grasses that have much shorter lives. [source]

    Local adaptation to biotic factors: reciprocal transplants of four species associated with aromatic Thymus pulegioides and T. serpyllum

    JOURNAL OF ECOLOGY, Issue 5 2008
    Eva Grøndahl
    Summary 1A plant producing secondary compounds may affect the fitness of other plants in the vicinity, and, likewise, associated plants may evolve adaptation to the presence of their ,chemical neighbour'. Species of the genus Thymus are aromatic plants, well known for their production of aromatic oils whose constitution is dominated by mono- or sesquiterpenes. A polymorphism for the production of the dominant terpene in the oil exists both within and between thyme species. 2Here we examine the effects of two different terpenes produced by Thymus pulegioides and T. serpyllum on the performance of four associated plant species: Achillea millefolium, Agrostis capillaris, Galium verum and Plantago lanceolata. In a reciprocal transplant experiment we studied how plants naturally occurring together with thyme producing either carvacrol or b-caryophyllene perform on soil treated with these compounds. 3We found evidence of local adaptation to the ,home' terpene. Plants originating from sites where they grow together with carvacrol-producing thyme plants also perform better on soil treated with carvacrol. One of the associated species (A. millefolium) also showed evidence of local adaptation to the sesquiterpene b-caryophyllene . 4Seed germination and root biomass showed an adaptive response to soil treatment. Vegetation analysis supported the results of the reciprocal transplant experiment. When the associated species performed best on ,home' soil, thyme and the associated species also showed a positive spatial association at natural sites of origin. Moreover, coefficients of variation in plant traits were significantly lower on ,home' soil compared to other soils for both A. capillaris and A. millefolium, but higher for G. verum. 5Synthesis. Our results show that plant species can adapt to the presence of neighbour plants that produce specific chemical compounds. This supports the idea that local plant communities may be a lot more co-evolved than was previously thought. [source]

    Extending point pattern analysis for objects of finite size and irregular shape

    JOURNAL OF ECOLOGY, Issue 4 2006
    Summary 1We use a grid- and simulation-based approach to extend point pattern analysis to deal with plants of finite size and irregular shape, and compare the results of our approach with that of the conventional point approximation. The plants are approximated by using an underlying grid and may occupy several adjacent grid cells depending on their size and shape. Null models correspond to that of point pattern analysis but need to be modified to account for the finite size and irregular shape of plants. 2We use a mapped area of a grass-shrub steppe in semi-arid Patagonia, Argentina, to show that the shrub community is essentially randomly structured, but that shrubs facilitate grasses in their immediate neighbourhood. 3The occurrence of this random spatial structure provides important new information on the biology of shrub populations. In general, previous data from semi-arid and arid ecosystems have shown that adult shrubs tend to show over-dispersed patterns, whereas juveniles are clumped. 4We find that the point approximation may produce misleading results (i) if plant size varies greatly, (ii) if the scale of interest is of the same order of magnitude as the size of the plants, and (iii) if the plants of a given pattern are constrained through competition for space by the presence of other plants. The point approximation worked well in all other cases, but usually depicted weaker significant effects than when the size and shape of plants were taken into account. 5Our approach to quantifying small-scale spatial patterns in plant communities has broad applications, including the study of facilitation and competition. Ecologists will be able to use the software available to take advantage of these methods. [source]

    Linking physiological traits to impacts on community structure and function: the role of root hemiparasitic Orobanchaceae (ex-Scrophulariaceae)

    JOURNAL OF ECOLOGY, Issue 1 2005
    Summary 1The hemiparasitic Orobanchaceae (ex-Scrophulariaceae) are characterized by a distinctive suite of ecophysiological traits. These traits have important impacts on host plants and non-host plants, and influence interactions with other trophic levels. Ultimately, they can affect community structure and functioning. Here, we review these physiological traits and discuss their ecological consequences. 2The root hemiparasitic Orobanchaceae form a convenient subset of the parasitic angiosperms for study because: they are the most numerous and most widely distributed group of parasitic angiosperms; their physiological characteristics have been well studied; they are important in both agricultural and (semi)natural communities; and they are tractable as experimental organisms. 3Key traits include: high transpiration rates; competition with the host for nutrients and haustorial metabolism of host-derived solutes; uptake of host-derived secondary metabolites; dual autotrophic and heterotrophic carbon nutrition; distinct carbohydrate biochemistry; high nutrient concentrations in green leaf tissue and leaf litter; and small (often hairless and non-mycorrhizal) roots. 4Impacts on the host are detrimental, which can alter competitive balances between hosts and non-hosts and thus result in community change. Further impacts may result from effects on the abiotic environment, including soil water status, nutrient cycling and leaf/canopy temperatures. 5However, for non-host species and for organisms that interact with these (e.g. herbivores and pollinators) or for those that benefit from changes in the abiotic environment, the parasites may have an overall positive effect, suggesting that at the community level, hemiparasites may also be considered as mutualists. 6It is clear that through their distinctive suite of physiological traits hemiparasitic Orobanchaceae, have considerable impacts on community structure and function, can have both competitive and positive interactions with other plants, and can impact on other trophic levels. Many community level effects of parasitic plants can be considered analogous to those of other parasites, predators or herbivores. [source]

    Pollution and Cost in the Coke-Making Supply Chain in Shanxi Province, China

    Applying an Integrated System Model to Siting, Transportation Trade-Offs
    Summary An integrated system trade-off model has been developed to assess costs and pollution associated with transportation in the coke-making supply chain in Shanxi Province, China. A transportation-flow, cost-minimization solver is combined with models for calculating coke-making plant costs, estimating transportation costs from a geographic information system road and rail database, and aggregating coke-making capacity among plants. Model outputs of economic cost, nitrogen oxides (NOx) emissions, and transport distributions are visualized using an Internet-based graphic user interface. Data for the model were collected on survey trips to Shanxi Province as well as from secondary references and proxies. The modularity and extensibility of the system trade-off model facilitate introduction of new data sets in order to examine various planning scenarios. Scenarios of coke-making plant aggregation, rail infrastructure improvement, and technology transfer were evaluated using the model. Costs and pollution emissions can be reduced by enlarging coke-making plants near the rail stations and closing down other plants. Preferential minimization of transportation costs gives a lower total cost than simply minimizing plant costs. Therefore, policy makers should consider transportation costs when planning the reallocation of coke-making capacity in Shanxi Province. Increasing rail-transport capacity is less effective than aggregating plant capacity. On the other hand, transfer of low-pollution truck technology results in a large emission reduction, however, reflecting the importance of truck transportation in the Shanxi Province coke-making industry. [source]

    The WRKY Gene Family in Rice (Oryza sativa)

    Christian A. Ross
    Abstract WRKY genes encode transcription factors that are involved in the regulation of various biological processes. These zinc-finger proteins, especially those members mediating stress responses, are uniquely expanded in plants. To facilitate the study of the evolutionary history and functions of this supergene family, we performed an exhaustive search for WRKY genes using HMMER and a Hidden Markov Model that was specifically trained for rice. This work resulted in a comprehensive list of WRKY gene models in Oryza sativa L. ssp. indica and L. ssp. japonica. Mapping of these genes to individual chromosomes facilitated elimination of the redundant, leading to the identification of 98 WRKY genes in japonica and 102 in indica rice. These genes were further categorized according to the number and structure of their zinc-finger domains. Based on a phylogenetic tree of the conserved WRKY domains and the graphic display of WRKY loci on corresponding indica and japonica chromosomes, we identified possible WRKY gene duplications within, and losses between the two closely related rice subspecies. Also reviewed are the roles of WRKY genes in disease resistance and responses to salicylic acid and jasmonic acid, seed development and germination mediated by gibberellins, other developmental processes including senescence, and responses to abiotic stresses and abscisic acid in rice and other plants. The signaling pathways mediating WRKY gene expression are also discussed. [source]

    Rice Mitochondrial Genes Are Transcribed by Multiple Promoters That Are Highly Diverged

    Qun-Yu Zhang
    Abstract Plant mitochondrial genes are often transcribed into complex sets of mRNA. To characterize the transcription initiation and promoter structure, the transcript termini of four mitochondrial genes, atp1, atp6, cob, rps7, in rice (Oryza sativa L.), were determined by using a modified circularized RNA reverse transcription-polymerase chain reaction method. The results revealed that three genes (atp1, atp6, rps7) were transcribed from multiple initiation sites, indicating the presence of multiple promoters. Two transcription termination sites were detected in three genes (atp6, cob, rps7), respectively. Analysis on the promoter architecture showed that the YRTA (Y=T or C, R=A or G) motifs that are widely present in the mitochondrial promoters of other monocotand dicot plant species were detected only in two of the 12 analyzed promoters. Our data suggest that the promoter sequences in the rice mitochondrial genome are highly diverged in comparison to those in other plants, and the YRTA motif is not an essential element for the promoter activity. (Managing editor: Li-Hui Zhao) [source]

    Late Quaternary vegetation changes around Lake Rutundu, Mount Kenya, East Africa: evidence from grass cuticles, pollen and stable carbon isotopes

    Dr M. J. Wooller
    Abstract Woody, subalpine shrubs and grasses currently surround Lake Rutundu, Mount Kenya. Multiple proxies, including carbon isotopes, pollen and grass cuticles, from a 755-cm-long core were used to reconstruct the vegetation over the past 38 300 calendar years. Stable carbon-isotope ratios of total organic carbon and terrestrial biomarkers from the lake sediments imply that the proportion of terrestrial plants using the C4 photosynthetic pathway was greater during the Late Pleistocene than in the Holocene. Pollen data show that grasses were a major constituent of the vegetation throughout the Late Pleistocene and Holocene. The proportion of grass pollen relative to the pollen from other plants was greatest at the last glacial maximum (LGM). Grass cuticles confirm evidence that C4 grass taxa were present at the LGM and that the majority followed the cold-tolerant NADP-MEC4 subpathway. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Stacking interaction study of trans -resveratrol (trans -3,5,4,-trihydroxystilbene) in solution by Nuclear Magnetic Resonance and Fourier Transform Infrared Spectroscopy

    Claudia Bonechi
    Abstract Interactions between aromatic rings or other unsaturated systems, including ,-stacking and face-to-edge complexes, are the origin of many phenomena in both organic and biological chemistry. It is well known that these interactions play an important role in the stabilization of the stereo-structure of DNA and the tertiary structure of many proteins. Trans -resveratrol (trans -3,5,4,-trihydroxystilbene, trans -RSV) is a phytoalexin found in Vitis sp. and in many other plants and food products and has received much attention because of its possible positive health benefits. In this work, the ,-stacking interaction of trans -RSV was studied by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. In particular, the proton chemical shift dependence of the RSV concentration in the range 2 × 10,2 , 1 × 10,5M and temperature were analysed. Moreover, the dynamics of the supramolecular aggregates were studied by nuclear spin relaxation data. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Structural analysis of 3-,-acetyl-20(29)-lupene-24-oic acid, a novel pentacyclic triterpene isolated from the gum resin of Boswellia serrata, by NMR spectroscopy

    Klaus Belsner
    Abstract 3,-Acetyl-20(29)-lupene-24-oic acid (1) was isolated from the gum resin of Boswellia serrata. Its presence evidently suggests, that the oxidosqualene triterpene pathway of Boswellia serrata closely resembles the biosynthetic route already found in other plants. Complete 1H and 13C spectral assignments were derived from 1D and 2D NMR spectra. This is the first compound with the lupene backbone combining a 3,-hydroxy or 3,-acetyl group with the 24-carboxyl group, a configuration which is typical of the classical boswellic acids. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Comparative analysis of the within-population genetic structure in wild cherry (Prunus avium L.) at the self-incompatibility locus and nuclear microsatellites

    MOLECULAR ECOLOGY, Issue 11 2006
    Abstract Gametophytic self-incompatibility (SI) systems in plants exhibit high polymorphism at the SI controlling S -locus because individuals with rare alleles have a higher probability to successfully pollinate other plants than individuals with more frequent alleles. This process, referred to as frequency-dependent selection, is expected to shape number, frequency distribution, and spatial distribution of self-incompatibility alleles in natural populations. We investigated the genetic diversity and the spatial genetic structure within a Prunus avium population at two contrasting gene loci: nuclear microsatellites and the S -locus. The S -locus revealed a higher diversity (15 alleles) than the eight microsatellites (4,12 alleles). Although the frequency distribution of S -alleles differed significantly from the expected equal distribution, the S -locus showed a higher evenness than the microsatellites (Shannon's evenness index for the S -locus: E = 0.91; for the microsatellites: E = 0.48,0.83). Also, highly significant deviations from neutrality were found for the S -locus whereas only minor deviations were found for two of eight microsatellites. A comparison of the frequency distribution of S -alleles in three age-cohorts revealed no significant differences, suggesting that different levels of selection acting on the S -locus or on S- linked sites might also affect the distribution and dynamics of S -alleles. Autocorrelation analysis revealed a weak but significant spatial genetic structure for the multilocus average of the microsatellites and for the S -locus, but could not ascertain differences in the extent of spatial genetic structure between these locus types. An indirect estimate of gene dispersal, which was obtained to explain this spatial genetic pattern, indicated high levels of gene dispersal within our population (,g = 106 m). This high gene dispersal, which may be partly due to the self-incompatibility system itself, aids the effective gene flow of the microsatellites, thereby decreasing the contrast between the neutral microsatellites and the S -locus. [source]

    Effect of genotype and environment on branching in weedy green millet (Setaria viridis) and domesticated foxtail millet (Setaria italica) (Poaceae)

    MOLECULAR ECOLOGY, Issue 5 2006
    Abstract Many domesticated crops are derived from species whose life history includes weedy characteristics, such as the ability to vary branching patterns in response to environmental conditions. However, domesticated crop plants are characterized by less variable plant architecture, as well as by a general reduction in vegetative branching compared to their progenitor species. Here we examine weedy green millet and its domesticate foxtail millet that differ in the number of tillers (basal branches) and axillary branches along each tiller. Branch number in F2:3 progeny of a cross between the two species varies with genotype, planting density, and other environmental variables, with significant genotype,environment interactions (GEI). This is shown by a complex pattern of reaction norms and by variation in the pattern of significant quantitative trait loci (QTL) amongst trials. Individual and joint analyses of high and low density trials indicate that most QTL have significant GEI. Dominance and epistasis also explain some variation in branching. Likely candidate genes underlying the QTL (based on map position and phenotypic effect) include teosinte branched1 and barren stalk1. Phytochrome B, which has been found to affect response to shading in other plants, explains little or no variation. Much variation in branching is explained by QTL that do not have obvious candidate genes from maize or rice. [source]

    Soft rot erwiniae: from genes to genomes

    Ian K. Toth
    SUMMARY The soft rot erwiniae, Erwinia carotovora ssp. atroseptica (Eca), E. carotovora ssp. carotovora (Ecc) and E. chrysanthemi (Ech) are major bacterial pathogens of potato and other crops world-wide. We currently understand much about how these bacteria attack plants and protect themselves against plant defences. However, the processes underlying the establishment of infection, differences in host range and their ability to survive when not causing disease, largely remain a mystery. This review will focus on our current knowledge of pathogenesis in these organisms and discuss how modern genomic approaches, including complete genome sequencing of Eca and Ech, may open the door to a new understanding of the potential subtlety and complexity of soft rot erwiniae and their interactions with plants. Taxonomy: ,The soft rot erwiniae are members of the Enterobacteriaceae, along with other plant pathogens such as Erwinia amylovora and human pathogens such as Escherichia coli, Salmonella spp. and Yersinia spp. Although the genus name Erwinia is most often used to describe the group, an alternative genus name Pectobacterium was recently proposed for the soft rot species. Host range:,Ech mainly affects crops and other plants in tropical and subtropical regions and has a wide host range that includes potato and the important model host African violet ( Saintpaulia ionantha ). Ecc affects crops and other plants in subtropical and temperate regions and has probably the widest host range, which also includes potato. Eca , on the other hand, has a host range limited almost exclusively to potato in temperate regions only. Disease symptoms: ,Soft rot erwiniae cause general tissue maceration, termed soft rot disease, through the production of plant cell wall degrading enzymes. Environmental factors such as temperature, low oxygen concentration and free water play an essential role in disease development. On potato, and possibly other plants, disease symptoms may differ, e.g. blackleg disease is associated more with Eca and Ech than with Ecc. Useful websites: ,http://www.scri.sari.ac.uk/TiPP/Erwinia.htm, http://www.ahabs.wisc.edu:16080/pernalab/erwinia/index.htm, http://www.tigr.org/tdb/mdb/mdbinprogress.html, http://www.sanger.ac.uk/Projects/E_carotovora/. [source]

    Microarray analysis of chitin elicitation in Arabidopsis thaliana

    Katrina M. Ramonell
    Summary Chitin oligomers, released from fungal cell walls by endochitinase, induce defence and related cellular responses in many plants. However, little is known about chitin responses in the model plant Arabidopsis. We describe here a large-scale characterization of gene expression patterns in Arabidopsis in response to chitin treatment using an Arabidopsis microarray consisting of 2375 EST clones representing putative defence-related and regulatory genes. Transcript levels for 71 ESTs, representing 61 genes, were altered three-fold or more in chitin-treated seedlings relative to control seedlings. A number of transcripts exhibited altered accumulation as early as 10 min after exposure to chitin, representing some of the earliest changes in gene expression observed in chitin-treated plants. Included among the 61 genes were those that have been reported to be elicited by various pathogen-related stimuli in other plants. Additional genes, including genes of unknown function, were also identified, broadening our understanding of chitin-elicited responses. Among transcripts with enhanced accumulation, one cluster was enriched in genes with both the W-box promoter element and a novel regulatory element. In addition, a number of transcripts had decreased abundance, encoding several proteins involved in cell wall strengthening and wall deposition. The chalcone synthase promoter element was identified in the upstream regions of these genes, suggesting that pathogen signals may suppress the expression of some genes. These data indicate that Arabidopsis should be an excellent model to elucidate the mechanisms of chitin elicitation in plant defence. [source]

    Conundrums of competitive ability in plants: what to measure?

    OIKOS, Issue 3 2002
    A survey of recent literature indicates that competitive ability in plants has been measured, in most studies, only in terms of the relative intensity of size suppression experienced by competitors within one growing season. Far fewer studies have recorded relative success in terms of survival and even fewer studies have recorded fecundity under competition. Differences in size suppression are usually assumed to reflect differences in relative abilities to deny resources to competitors. However, most previous studies have failed to control or account for other sources of variation in the size suppression that plants experience under competition, i.e. variation between mixtures in the resource supply/demand ratio (approach to carrying capacity), or variation in the degree of niche overlap between competitors, or variation in the intensity of concurrent facilitative interactions between competitors. For future studies, much greater caution is required in recognizing these inherent limitations of traditional measures of competitive ability and, hence, guarding against unfounded conclusions or predictions about potential for competitive success that are based on these measures. There is also a significant challenge for future studies to adopt empirical approaches for minimizing these limitations. Some initial recommendations are considered here based on an emerging view of competitive ability measured in terms of traits associated with all three conventional components of Darwinian fitness, i.e. not just growth (plant size) but also survival and fecundity allocation (offspring production per unit plant size per unit time). According to this model, differences in competitive ability imply differences in the ability, despite intense competition (i.e. low resource supply/demand ratio), to recruit offspring into the next generation and thereby limit offspring recruitment by other plants. The important traits of competitive ability, therefore, are not only those that allow a plant to deny resources to competitors, suppress their sizes and hence, maximize the plant's own size, but also those traits that allow the plant to withstand suppression from competition enough to persist, both as an individual (through survival) and across generations (through descendants). [source]

    Rare species in communities of tropical insect herbivores: pondering the mystery of singletons

    OIKOS, Issue 3 2000
    Vojtech Novotný
    The host specificity, taxonomic composition and feeding guild of rare species were studied in communities of herbivorous insects in New Guinea. Leaf-chewing and sap-sucking insects (Orthoptera, Phasmatodea, Coleoptera, Lepidoptera and Hemiptera-Auchenorrhyncha) were sampled from 30 species of trees and shrubs (15 spp. of Ficus, Moraceae, six spp. of Macaranga and nine species of other Euphorbiaceae) in a lowland rain forest. Feeding trials were performed with all leaf-chewers in order to exclude transient species. Overall, the sampling produced 80,062 individuals of 1050 species. The species accumulation curve did not attain an asymptote, despite 950 person-days of sampling. Rare species, defined as those found as single individuals, remained numerous even in large samples and after the exclusion of transient, non-feeding species. There was no difference among plant species in the proportion of rare species in their herbivore communities, which was, on average, 45%. Likewise, various herbivore guilds and taxa had all very similar proportions of rare and common species. There was also no difference between rare and common species in their host specificity. Both highly specialised species and generalists, feeding on numerous plants, contributed to the singleton records on particular plant species. Predominantly, a species was rare on a particular host whilst more common on other, often related, host species, or relatively rare on numerous other host plants, so that its aggregate population was high. Both cases are an example of the "mass effect", since it is probable that such rare species were dependent on a constant influx of immigrants from the other host plants. These other plants were found particularly often among congeneric plants, less so among confamilial plants from different genera and least frequently among plants from different families. There were also 278 very rare species, found as one individual on a single plant species only. Their host specificity could not be assessed; they might have been either very rare specialists, or species feeding also on other plants, those that were not studied. The former possibility is unlikely since monophagous species, collected as singletons at the present sampling effort, would have existed at an extremely low population density, less than 1 individual per 10 ha of the forest. [source]

    A psbA mutation in Kochia scoparia (L) Schrad from railroad rights-of-way with resistance to diuron, tebuthiuron and metribuzin,

    Lemma W Mengistu
    Abstract Kochia [Kochia scoparia (L) Schrad] has become resistant to many herbicides used in cropland and railroad rights-of-way in North Dakota and Minnesota. Kochia scoparia plants that had survived annual treatments with diuron and tebuthiuron were sampled along railroad rights-of-way in North Dakota and Minnesota. The samples were screened in the greenhouse for resistance to diuron, tebuthiuron, metribuzin and bromoxynil from 0.5× to 32× the recommended use rates. A resistant K scoparia accession (MN-3R) was confirmed with resistance up to 16-fold higher than recommended use rates for tebuthiuron and diuron and up to 4-fold higher for metribuzin. However, the resistant K scoparia accession was susceptible to bromoxynil even at 50% of the recommended use rate. The herbicide binding region of the psbA gene fragment of eight resistant (R) and seven susceptible (S) K scoparia accessions was PCR-amplified and sequenced for detection of mutations. The psbA gene of four R K scoparia accessions was mutated at residue 219 with substitution of isoleucine for valine (GenBank accession number AY251265). The seven S K scoparia accession sequences were wild-type at this residue (GenBank accession number AY251266). The other four R accessions sequences showed a previously known triazine R mutation with substitution of glycine for serine at residue 264. All 15 K scoparia accessions were wild-type at all other psbA residues within the region analyzed. Resistance to diuron, tebuthiuron and metribuzin among the railroad rights-of-way K scoparia is probably due to the mutation at residue 219 of the psbA gene in some plants, but due to the previously reported Ser264Gly substitution in other plants. Target-site resistance associated with a change of valine to isoleucine at residue 219 of the psbA target-site in weeds has previously been reported for Poa annua L selected in diuron-treated grass seed fields, and for Amaranthus powelli S Wats selected in linuron-treated carrot fields. This is the first report of the mutation in herbicide-resistant K scoparia. Copyright © 2005 Society of Chemical Industry [source]

    A new catalytic activity from tobacco converting 2-coumaric acid to salicylic aldehyde

    Jacek Malinowski
    Salicylic acid (SA) mediates plant response to pathogen invasion, resulting in hypersensitive response and in the formation of systemic acquired resistance. It is well known that Nicotiana tabacum and other plants respond to Tobacco Mosaic Virus (TMV) infection by increasing the content of SA but the details of SA biosynthesis are still not fully understood. Generally, SA may originate directly from isochorismate (Arabidopsis thaliana), or its C6,C1 skeleton could be synthesized via the phenylpropanoid pathway by ,-oxidation of trans -cinnamic acid (N. tabacum), 2-coumaric acid (OCA) (Gaulteria procumbens, Lycopersicum esculentum) or by retro-aldol reaction of trans -cinnamoyl-CoA (Hypericum androsaemum). We report here a novel putative enzyme activity from tobacco, salicylic aldehyde synthase (SAS), catalysing non-oxidative formation of salicylic aldehyde (SALD) directly from OCA. This chain-shortening activity is similar to that of 4-hydroxybenzaldehyde synthase from Vanilla planifolia, Lithospermum erythrorhizon, Daucus carota, Solanum tuberosum and Polyporus hispidus but the enzyme differs in the kinetics of the reaction, substrate specificity and requirements for reducing cofactors. SAS activity is constitutively expressed in healthy tobacco leaves and doubles as a result of infection with TMV. Moreover, the product of SAS activity,SALD, applied exogenously on tobacco leaves, stimulates peroxidase activity and enhances resistance to consecutive infection with TMV. These observations could suggest a contribution of SAS and SALD to the response of tobacco to TMV infection. [source]

    Pharmacological and therapeutic effects of Berberis vulgaris and its active constituent, berberine

    Mohsen Imanshahidi
    Abstract Barberry (Berberis vulgaris L. family Berberidaceae) is well known in Iran and various parts of this plant including its root, bark, leaf and fruit have been used as folk medicine. The two decades of research has demonstrated different pharmacological and therapeutic effects of B. vulgaris and its isoquinoline alkaloids (particularly berberine). Studies carried out on the chemical composition of the plant show that the most important constituents of this plant are isoquinoline alkaloids such as berberine, berbamine and palmatine. Berberine represents one of the most studied among the naturally occurring protoberberine alkaloids. In addition to B. vulgaris (barberry), berberine is present in many other plants and is used for the treatment of different diseases. This article reviews the traditional uses and pharmacological effects of total extract and the most active ingredient of B. vulgaris (berberine). Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Protective effects of selected medicinal plants against protein degradation, lipid peroxidation and deformability loss of oxidatively stressed human erythrocytes

    S. M. Suboh
    Abstract The effects of seven medicinal plants including Artemisia herba-alba, Ferula hermonis, Hibiscus sabdariffa, Nigella sativa, Teucrium polium, Trigonella foenum-graecum, and Allium sativum on protein degradation, lipid peroxidation, erythrocyte deformability and osmotic fragility of erythrocytes exposed in vitro to 10 mM H2O2 for 60 min at 37 °C have been examined. Preincubation of erythrocytes with Nigella sativa and Allium sativum protected erythrocytes against protein degradation, loss of deformability and increased osmotic fragility caused by H2O2, while the other plants failed to protect erythrocytes against these damages. Artemisia herba-alba did not protect erythrocytes against lipid peroxidation, while Trigonella foenum-graecum unexpectedly increased lipid peroxidation of erythrocytes exposed to H2O2. Ferula hermonis, Hibiscus sabdariffa, Nigella sativa, Teucrium polium and Allium sativum protected erythrocytes against lipid peroxidation. The results indicate the importance of oxidatively damaged cellular proteins in compromising the rheologic behaviour of the erythrocytes, and that the medicinal plants which have anti-protein-oxidant activity (e.g. Nigella sativa and Allium sativum) could be rheologically useful, particularly in pathological conditions related to free radicals. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Parasitism by Cuscuta pentagona sequentially induces JA and SA defence pathways in tomato

    PLANT CELL & ENVIRONMENT, Issue 2 2010
    ABSTRACT While plant responses to herbivores and pathogens are well characterized, responses to attack by other plants remain largely unexplored. We measured phytohormones and C18 fatty acids in tomato attacked by the parasitic plant Cuscuta pentagona, and used transgenic and mutant plants to explore the roles of the defence-related phytohormones salicylic acid (SA) and jasmonic acid (JA). Parasite attachment to 10-day-old tomato plants elicited few biochemical changes, but a second attachment 10 d later elicited a 60-fold increase in JA, a 30-fold increase in SA and a hypersensitive-like response (HLR). Host age also influenced the response: neither Cuscuta seedlings nor established vines elicited a HLR in 10-day-old hosts, but both did in 20-day-old hosts. Parasites grew larger on hosts deficient in SA (NahG) or insensitive to JA [jasmonic acid-insensitive1 (jai1) ], suggesting that both phytohormones mediate effective defences. Moreover, amounts of JA peaked 12 h before SA, indicating that defences may be coordinated via sequential induction of these hormones. Parasitism also induced increases in free linolenic and linoleic acids and abscisic acid. These findings provide the first documentation of plant hormonal signalling induced by a parasitic plant and show that tomato responses to C. pentagona display characteristics similar to both herbivore- and pathogen-induced responses. [source]