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Sample records for allelochemicals

  1. Mechanism and active variety of allelochemicals

    Science.gov (United States)

    Peng, S.-L.; Wen, J.; Guo, Q.-F.

    2004-01-01

    This article summarizes allelochemicals' active variety, its potential causes and function mechanisms. Allelochemicals' activity varies with temperature, photoperiod, water and soils during natural processes, with its initial concentration, compound structure and mixed degree during functional processes, with plant accessions, tissues and maturity within-species, and with research techniques and operation processes. The prospective developmental aspects of allelopathy studies in the future are discussed. Future research should focus on: (1) to identify and purify allelochemicals more effectively, especially for agriculture, (2) the functions of allelopathy at the molecular structure level, (3) using allelopathy to explain plant species interactions, (4) allelopathy as a driving force of succession, and (5) the significance of allelopathy in the evolutionary processes.

  2. Bioassay of naturally occurring allelochemicals for phytotoxicity.

    Science.gov (United States)

    Leather, G R; Einhellig, F A

    1988-10-01

    The bioassay has been one of the most widely used tests to demonstrate allelopathic activity. Often, claims that a particular plant species inhibits the growth of another are based entirely on the seed germination response to solvent extracts of the suspected allelopathic plant; few of these tests are of value in demonstrating allelopathy under natural conditions. The veracity of the bioassay for evaluating naturally occurring compounds for phytotoxicity depends upon the physiological and biochemical response capacity of the bioassay organism and the mechanism(s) of action of the allelochemicals. The possibility that more than one allelochemical, acting in concert at very low concentrations, may be responsible for an observed allelopathic effect makes it imperative that bioassays be extremely sensitive to chemical growth perturbation agents. Among the many measures of phytotoxicity of allelochemicals, the inhibition (or stimulation) of seed germination, radicle elongation, and/or seedling growth have been the parameters of choice for most investigations. Few of these assays have been selected with the view towards the possible mechanism of the allelopathic effect.

  3. Autotoxicity in Pogostemon cablin and their allelochemicals

    Directory of Open Access Journals (Sweden)

    Yan Xu

    Full Text Available Abstract The effects of allelochemicals and aqueous extracts from different Pogostemon cablin (Blanco Benth., Lamiaceae, parts and rhizosphere soil on growth parameters, leaf membrane peroxidation and leaf antioxidant enzymes were investigated in patchouli. P. cablin seedlings were incubated in solutions containing allelochemicals and aqueous extracts from different patchouli parts and its rhizosphere soil at several concentrations. Firstly, the growth parameters were significantly reduced by the highest concentration of leaves, roots and stems extracts (p < 0.05. As compared to the control, plant height was reduced by 99.8% in the treatment with leaves extracts (1:10. The malondialdehyde content increased greatly when patchouli seedlings were subject to different concentrations of leaves, roots and stems extracts; meanwhile, the superoxide dismutase and peroxidase activities showed an increase trend at the low concentration, followed by a decline phase at the high concentration of roots and leaves extracts (1:10. What's more, leaves and roots extracts had a more negative effect on patchouli growth than stems extracts at the same concentrations. Secondly, the total fresh mass, root length and plant height were greatly reduced by the highest strength of soil extracts. Their decrements were 22.7, 74.9, and 33.1%, respectively. Thirdly, growth parameters and enzymatic activities varied considerably with the kinds of allelochemicals and with the different concentrations. Plant height, root length and total fresh weight of patchouli were greatly reduced by p-hydroxybenzoic acid (200 μM, and their decrements were 77.0, 42.0 and 70.0%, respectively. Finally, three useful measures on reducing the autotoxicity during the sustainable patchouli production were proposed.

  4. Effects of Allelochemicals of Some Eucalyptus Species on ...

    African Journals Online (AJOL)

    A laboratory experiment was conducted to assess the effects of allelochemicals of Eucalyptus camaldulensis, Eucalyptus citriodora and Eucalyptus globules on germination and root elongation using leguminous crop ground nut (Arachis hypogea) as bioassay material. The experiments were conducted in sterilized ...

  5. Functional Characterization and Expression of Molluscan Detoxification Enzymes and Transporters Involved in Dietary Allelochemical Resistance

    National Research Council Canada - National Science Library

    Whalen, Kristen E

    2008-01-01

    The processes underlying dietary allelochemical tolerance are likely mediated, in part, by biochemical resistance mechanisms that have evolved under the selective pressure of host chemical defenses...

  6. Antialgal effects of five individual allelochemicals and their mixtures in low level pollution conditions.

    Science.gov (United States)

    Zuo, Shengpeng; Zhou, Shoubiao; Ye, Liangtao; Ding, Ying; Jiang, Xiaofeng

    2016-08-01

    An effective, environmentally friendly, and eco-sustainable approach for removing harmful microalgae is exploiting the allelopathic potential of aquatic macrophytes. In this study, we simulated field pollution conditions in the laboratory to investigate algal inhibition by allelochemicals, thereby providing insights into field practices. We tested five allelochemicals, i.e., coumarin, ρ-hydroxybenzoic acid, protocatechuic acid, stearic acid, and ρ-aminobenzenesulfonic acid, and a typical green alga, Chlorella pyrenoidosa, under two conditions. In the unpolluted treatment, individual allelochemicals had strong algal inhibition effects, where coumarin and ρ-hydroxybenzoic acid had greater potential for algal inhibition than protocatechuic acid, stearic acid, and ρ-aminobenzenesulfonic acid based on the 50 % inhibitory concentration. However, when two or three allelochemicals were mixed in specific proportions, the algal inhibition rate exceeded 80 %, thereby indicating allelopathic synergistic interactions. Mixtures of four or five allelochemicals had weak effects on algal inhibition, which indicated antagonistic interactions. Furthermore, the presence of low lead pollution significantly reduced the antialgal potential of individual allelochemicals, whereas the allelopathic synergistic interactions with mixtures between two or three allelochemicals were changed into antagonistic effects by low pollution. In particular, the allelopathic antagonistic interactions between four or five allelochemicals were increased by pollution. The allelopathic performance of these five allelochemicals may depend on various factors, such as the chemical species, mixture parameters, and algal strain. Thus, we found that low level pollution reduced the allelopathic inhibition of microalgae by allelochemicals. Therefore, the control of algae by the direct addition of allelochemicals should consider various environmental factors.

  7. Allelochemical, Eudesmane-Type Sesquiterpenoids from Inula falconeri

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    Kazuo N. Watanabe

    2010-03-01

    Full Text Available We have identified through bioassay guided isolation an allelochemical, eudesmane-type sesquiterpeniod, 3β-caffeoxyl-β1,8α-dihydroxyeudesm-4(15-ene(1,from an endemic plant species growing in the Himalayas. In our search for the bioactive subfraction, the hexane one was highly significant, showing 100% inhibition of lettuce seed growth at 100 ppm while other subfractions (chloroform, ethyl acetate, butanol and water exhibited inhibitory to stimulatory allelopathic effects. The bioactive hexane subfraction was subjected to chromatographic techniques, using lettuce seeds (Lactuca sativa as indicator species to reveal the bioactive allelopathic fraction. This resulted in the isolation of compound 1, whose structure was elucidated through NMR techniques. The compound presented 92.34% inhibitory effect on the growth of lettuce at 500 ppm. Further field level experiments may help develop an environmentally friendly herbicide from this lead.

  8. Current Trends in the Studies of Allelochemicals for Their Application in Practice

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    Arsen V.Viter

    2015-06-01

    Full Text Available The allelochemicals have been largely used in agriculture, forestry, landscape design and ornamental plant growing for many decades. However, there is a lack of the comprehensive studies, where existing publications are analyzed and synthesized with regards to the theoretic aspects for such usage. The objective of this paper was to systemize the advances in the research on allelochemicals’ application in practice. Numerous novel methodological propositions have risen recently. We classified them into the physical, chemical, biological, biotechnological and cropgrowing approaches. The allelochemicals consist of the wide diversity of the substances according to their chemical nature. Among these substances we outlined, firstly, the unidentified plant exudates and the products of green manuring, secondly, the chemically characterized or purified substances, which include alcohols, organic acids, aliphatic compounds, aromatic, alicyclic and nitrogen-contain organic compounds. Several groups of the biotic sources of allelochemicals were described: dicotyledonous and monocotyledonous plants, particularly under their colonization by non-pathogenic strains of Fusarium oxysporum, marine flora and fungi, which exhibit the herbicidal activity. Different targets of the allelochemical application were listed in the paper and they were categorized into several groups: higher flora, animals, unicellular and multi-cellular fungi. We concluded that there is lack of the modern multifaceted knowledge bases for the information about the allelochemical application. Those knowledge bases must be useful in order to choose the appropriate biological method for solving each particular problem of plant cultivation. To that end we systemized the results of current investigation about the usage of allelochemicals in practice.

  9. Soil Microorganisms Alleviate the Allelochemical Effects of a Thyme Monoterpene on the Performance of an Associated Grass Species

    OpenAIRE

    Ehlers, Bodil K.

    2011-01-01

    Background Plant allelochemicals released into the soil can significantly impact the performance of associated plant species thereby affecting their competitive ability. Soil microbes can potentially affect the interaction between plant and plant chemicals by degrading the allelochemicals. However, most often plant-plant chemical interactions are studied using filter paper bioassays examining the pair-wise interaction between a plant and a plant chemical, not taking into account the potential...

  10. Phytotoxicity of vulpia residues: III. Biological activity of identified allelochemicals from Vulpia myuros.

    Science.gov (United States)

    An, M; Pratley, J E; Haig, T

    2001-02-01

    Twenty compounds identified in vulpia (Vulpia myuros) residues as allelochemicals were individually and collectively tested for biological activity. Each exhibited characteristic allelochemical behavior toward the test plant, i.e., inhibition at high concentrations and stimulation or no effect at low concentrations, but individual activities varied. Allelopathins present in large quantities, such as syringic, vanillic, and succinic acids, possessed low activity, while those present in small quantities, such as catechol and hydrocinnamic acid, possessed strong inhibitory activity. The concept of a phytotoxic strength index was developed for quantifying the biological properties of each individual allelopathin in a concise, comprehensive, and meaningful format. The individual contribution of each allelopathin, assessed by comparing the phytotoxic strength index to the overall toxicity of vulpia residues, was variable according to structure and was influenced by its relative proportion in the residue. The majority of compounds possessed low or medium biological activity and contributed most of the vulpia phytotoxicity, while compounds with high biological activity were in the minority and only present at low concentration. Artificial mixtures of these pure allelochemicals also produced phytotoxicity. There were additive/synergistic effects evident in the properties of these mixtures. One such mixture, formulated from allelochemicals found in the same proportions as occur in vulpia extract, produced stronger activity than another formulated from the same set of compounds but in equal proportions. These results suggest that the exploration of the relative composition of a cluster of allelopathins may be more important than simply focusing on the identification of one or two compounds with strong biological activity and that synergism is fundamental to the understanding of allelopathy.

  11. Herbicidal Activities of Some Allelochemicals and Their Synergistic Behaviors toward Amaranthus tricolor L.

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    Nawasit Chotsaeng

    2017-10-01

    Full Text Available Seven allelochemicals, namely R-(+-limonene (A, vanillin (B, xanthoxyline (C, vanillic acid (D, linoleic acid (E, methyl linoleate (F, and (±-odorine (G, were investigated for their herbicidal activities on Chinese amaranth (Amaranthus tricolor L.. At 400 μM, xanthoxyline (C showed the greatest inhibitory activity on seed germination and seedling growth of the tested plant. Both vanillic acid (D and (±-odorine (G inhibited shoot growth, however, apart from xanthoxyline (C, only vanillic acid (D could inhibit root growth. Interestingly, R-(+-limonene (A lightly promoted root length. Other substances had no allelopathic effect on seed germination and seedling growth of the tested plant. To better understand and optimize the inhibitory effects of these natural herbicides, 21 samples of binary mixtures of these seven compounds were tested at 400 μM using 0.25% (v/v Tween® 80 as a control treatment. The results showed that binary mixtures of R-(+-limonene:xanthoxyline (A:C, vanillin:xanthoxyline (B:C, and xanthoxyline:linoleic acid (C:E exhibited strong allelopathic activities on germination and seedling growth of the tested plant, and the level of inhibition was close to the effect of xanthoxyline (C at 400 µM and was better than the effect of xanthoxyline (C at 200 µM. The inhibition was hypothesized to be from a synergistic interaction of each pair of alleochemicals. Mole ratios of each pair of allelochemicals ((A:C, (B:C, and (C:E were then evaluated, and the best ratios of the binary mixtures A:C, B:C and C:E were found to be 2:8, 2:8, and 4:6 respectively. These binary mixtures significantly inhibited germination and shoot and root growth of Chinese amaranth at low concentrations. The results reported here highlight a synergistic behavior of some allelochemicals which could be applied in the development of potential herbicides.

  12. Allelochemicals and activities in a replanted Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) tree ecosystem.

    Science.gov (United States)

    Kong, C H; Chen, L C; Xu, X H; Wang, P; Wang, S L

    2008-12-24

    Autotoxicity is a major reason for replant problems in managed tree ecosystems. Studies have related phenolics-based allelochemicals to autotoxicity. We selected a 20-year-old replanted Chinese fir [Cunninghamia lancealata (Lamb.) Hook] tree ecosystem to isolate, identify, determine the biological activity of, and quantify soil phytotoxins. Eight common phenolics (coumarin, vanillin, isovanillin, and p-hydroxybenzoic, vanillic, benzoic, cinnamic, and ferulic acids), friedelin, and a novel cyclic dipeptide (6-hydroxy-1,3-dimethyl-8-nonadecyl-[1,4]-diazocane-2,5-diketone) were obtained by using the bioassay-guided isolation technique from toxic soil of the replanted Chinese fir tree ecosystem. Chemical structures were determined by spectroscopic means, including 2D-NMR (COSY, HMQC, HMBC, and NOESY) experiments. High concentrations of soil phenolics and friedelin were observed in the natural evergreen broadleaf forest (CK) rather than in the Chinese fir tree ecosystem. The phenolics and friedelin were not phytotoxic to Chinese fir trees. However, the cyclic dipeptide inhibited Chinese fir growth at soil concentrations determined in the replanted Chinese fir tree ecosystem. There was a significantly higher soil concentration of cyclic dipeptide in the replanted Chinese fir tree ecosystem than in a fresh Chinese fir tree ecosystem. The results suggest that phenolics and friedelin are not key allelochemicals since they are weakly phytotoxic and are detected in low concentrations in the replanted Chinese fir tree ecosystem, while cyclic dipeptide is a highly active allelochemical with a phytotoxic effect that limits offspring growth in the replanted Chinese fir tree ecosystem. The discovery of cyclic dipeptide, as well as a further understanding of its potential action mechanism in the replanted Chinese fir tree ecosystem, may contribute to solving the replant problems in managed tree ecosystems.

  13. Antioxidant enzyme level response to prooxidant allelochemicals in larvae of the southern armyworm moth, Spodoptera eridania.

    Science.gov (United States)

    Pritsos, C A; Ahmad, S; Elliott, A J; Pardini, R S

    1990-01-01

    Larvae of the southern armyworm, Spodoptera eridania, are highly polyphagous feeders which frequently encounter and feed upon plants containing high levels of prooxidant allelochemicals. While ingestion of moderate quantities of prooxidants can be tolerated by these larvae, ingestion of larger quantities can result in toxicity. Studies were conducted to assess the role of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) in the protection of S. eridania against redox active prooxidant plant allelochemicals. Dietary exposure of mid-fifth-instar larvae to either quercetin (a flavonoid) or xanthotoxin (a photoactive furanocoumarin), which generate superoxide radical, and singlet oxygen, respectively, resulted in an increase in SOD levels. CAT levels increased in all groups of S. eridania including control insects. This may have been due to the sudden exposure to food following an extended fast of 18 h (to insure that larvae would not reject the diet because of the prooxidants' bitter taste) with an eventual lowering of CAT values with time. GR activities did not significantly change except for a slight inhibition at the highest prooxidant concentrations used at 12-h post-ingestion. The data from these studies suggest that SOD responds to prooxidant challenges in these insects and together with CAT and GR contributes to the insect's defense against potentially toxic prooxidant compounds.

  14. Oxidative damage and cell-programmed death induced in Zea mays L. by allelochemical stress.

    Science.gov (United States)

    Ciniglia, Claudia; Mastrobuoni, Francesco; Scortichini, Marco; Petriccione, Milena

    2015-05-01

    The allelochemical stress on Zea mays was analyzed by using walnut husk washing waters (WHWW), a by-product of Juglans regia post-harvest process, which possesses strong allelopathic potential and phytotoxic effects. Oxidative damage and cell-programmed death were induced by WHWW in roots of maize seedlings. Treatment induced ROS burst, with excess of H2O2 content. Enzymatic activities of catalase were strongly increased during the first hours of exposure. The excess in malonildialdehyde following exposure to WHWW confirmed that oxidative stress severely damaged maize roots. Membrane alteration caused a decrease in NADPH oxidase activity along with DNA damage as confirmed by DNA laddering. The DNA instability was also assessed through sequence-related amplified polymorphism assay, thus suggesting the danger of walnut processing by-product and focusing the attention on the necessity of an efficient treatment of WHWW.

  15. Isolation of bioactive allelochemicals from sunflower (variety Suncross-42) through fractionation-guided bioassays.

    Science.gov (United States)

    Anjum, Tehmina; Bajwa, Rukhsana

    2010-11-01

    Plants are rich source of biologically active allelochemicals. However, natural product discovery is not an easy task. Many problems encountered during this laborious practice can be overcome through the modification of preliminary trials. Bioassay-directed isolation of active plant compounds can increase efficiency by eliminating many of the problems encountered. This strategy avoids unnecessary compounds, concentrating on potential components and thus reducing the cost and time required. In this study, a crude aqueous extract of sunflower leaves was fractionated through high performance liquid chromatography. The isolated fractions were checked against Chenopodium album and Rumex dentatus. The fraction found active against two selected weeds was re-fractionated, and the active components were checked for their composition. Thin layer chromatography isolated a range of phenolics, whereas the presence of bioactive terpenoids was confirmed through mass spectroscopy and nuclear magnetic resonance spectroscopy.

  16. Inhibition of Orobanche crenata seed germination and radicle growth by allelochemicals identified in cereals.

    Science.gov (United States)

    Fernández-Aparicio, Mónica; Cimmino, Alessio; Evidente, Antonio; Rubiales, Diego

    2013-10-16

    Orobanche crenata is a parasitic weed that causes severe yield losses in important grain and forage legume crops. Cereals have been reported to inhibit O. crenata parasitism when grown intercropped with susceptible legumes, but the responsible metabolites have not been identified. A number of metabolites have been reported in cereals that have allelopathic properties against weeds, pests, and pathogens. We tested the effect of several allelochemicals identified in cereals on O. crenata seed germination and radicle development. We found that 2-benzoxazolinone, its derivative 6-chloroacetyl-2-benzoxazolinone, and scopoletin significantly inhibited O. crenata seed germination. Benzoxazolinones, l-tryptophan, and coumalic acid caused the stronger inhibition of radicle growth. Also, other metabolites reduced radicle length, this inhibition being dose-dependent. Only scopoletin caused cell necrotic-like darkening in the young radicles. Prospects for their application to parasitic weed management are discussed.

  17. Effect of qualitative and quantitative variation in allelochemicals on a generalist insect: Iridoid glycosides and the southern armyworm.

    Science.gov (United States)

    Puttick, G M; Bowers, M D

    1988-01-01

    The behavioral and physiological effects of plant allelochemicals have been difficult to demonstrate; it is not often clear whether the compounds are deterrent, toxic, or both. In this study, we compared the qualitative and quantitative effects of several iridoid glycosides on a generalist lepidopteran herbivore,Spodoptera eridania (Noctuidae). Larval growth and survivorship and larval preference or avoidance were measured on artificial diets containing different iridoid glycosides at different concentrations. We also tested the toxicity/deterrence of these compounds. We found that iridoid glycosides retarded larval growth significantly at relatively low concentrations and that they were usually avoided in preference tests. The toxicity/ deterrence test did not always reflect the results of these other tests. The merits of using a variety of methods for determining deterrence and/or toxicity of plant allelochemicals are discussed.

  18. [Mechanism of the inhibitory action of allelochemical dibutyl phthalate on algae Gymnodinium breve].

    Science.gov (United States)

    Bie, Cong-Cong; Li, Feng-Min; Wang, Yi-Fei; Wang, Hao-Yun; Zhao, Ya-Han; Zhao, Wei; Wang, Zhen-Yu

    2012-01-01

    The aim of this study was to investigate the mechanism of inhibitory action of dibutyl phthalate (DBP) on red tide algae Gymnodinium breve. The effects of DBP on malonaldehyde, subcellular structure and superoxide dismutase (SOD) isoforms were investigated. The results showed that MDA accumulated in the algae cell under DBP exposure, and for the 3 mg x L(-1) DBP treated algae culture a peak value of 0.34 micromol x (10(9) cells) (-1) occurred at 72 h, which was about 2. 3 times than that of the control. TEM pictures showed the disruption of DBP on the subcellular structure of G. breve. A morphological phenomenon appeared that the algae cell was commonly found small tubules or apical parts around the cell membrane, and almost all normal cell organelles were indistinguishable finally. The activity of CuZn-SOD (main cytoplast located isoform with little in cloroplast) under DBP exposure was higher than that of the control, and no significant difference was observed on Fe-SOD (chloroplast located isoform) activity, but for the Mn-SOD (mitochondrial isoform), the activity was significantly inhibited. These results indicated that DBP might inhibit the algae growth from the plasma membrane and the mitochondria, resulting in oxidative damage in algae cell and a final death. This paper will give a theoretical support to the practical usage of the allelochemical on red tide algae.

  19. [Effects of allelochemical dibutyl phthalate on Gymnodinium breve reactive oxygen species].

    Science.gov (United States)

    Bie, Cong-Cong; Li, Feng-Min; Li, Yuan-Yuan; Wang, Zhen-Yu

    2012-02-01

    The purpose of this study was to investigate the mechanism of inhibitory action of dibutyl phthalate (DBP) on red tide algae Gymnodinium breve. Reactive oxygen species (ROS) level, contents of *OH and H2O2, and O2*(-) production rate were investigated, and also for the effects of electron transfer inhibitors on the ROS induction of DBP. The results showed that DBP triggered the synthesis of reactive oxygen species ROS, and with the increase of concentration of DBP, *OH and H2O2 contents in cells accumulated, as for the 3 mg x L(-1) DBP treated algae cultures, OH showed a peak of 33 U x mL(-1) at 48 h, which was about 2. 4 times higher than that in the controlled, and H2O2 contents was about 250 nmol x (10(7) cells)(-1) at 72 h, which was about 5 times higher and also was the highest during the whole culture. Rotenone (an inhibitor of complex I in the mitochondria electron transport chain) decreased the DBP induced ROS production, and dicumarol (an inhibitor of the redox enzyme system in the plasma membrane) stimulated the DBP induced ROS production. Taken all together, the results demonstrated DBP induced over production of reactive oxygen species in G. breve, which is the main inhibitory mechanism, and mitochondria and plasma membrane seem to be the main target site of DBP. These conclusions were of scientific meaning on uncovering the inhibitory mechanism of allelochemical on algae.

  20. Changes over time in the allelochemical content of ten cultivars of rye (Secale cereale L.).

    Science.gov (United States)

    Reberg-Horton, S Chris; Burton, James D; Danehower, David A; Ma, Guoying; Monks, David W; Murphy, J Paul; Ranells, Noah N; Williamson, John D; Creamer, Nancy G

    2005-01-01

    Published studies focused on characterizing the allelopathy-based weed suppression by rye cover crop mulch have provided varying and inconsistent estimates of weed suppression. Studies were initiated to examine several factors that could influence the weed suppressiveness of rye: kill date, cultivar, and soil fertility. Ten cultivars of rye were planted with four rates of nitrogen fertilization, and tissue from each of these treatment combinations was harvested three times during the growing season. Concentrations of a known rye allelochemical DIBOA (2,4-dihydroxy-1,4-(2H)benzoxazine-3-one) were quantified from the harvested rye tissue using high performance liquid chromatography (HPLC). Phytotoxicity observed from aqueous extracts of the harvested rye tissue correlated with the levels of DIBOA recovered in harvested tissue. The amount of DIBOA in rye tissue varied depending on harvest date and rye cultivar, but was generally lower with all cultivars when rye was harvested later in the season. However, the late maturing variety 'Wheeler' retained greater concentrations of DIBOA in comparison to other rye cultivars when harvested later in the season. The decline in DIBOA concentrations as rye matures, and the fact that many rye cultivars mature at different rates may help explain why estimates of weed suppression from allelopathic agents in rye have varied so widely in the literature.

  1. ESTRESSE OXIDATIVO EM CÉLULAS VEGETAIS MEDIANTE ALELOQUÍMICOS OXIDATIVE STRESS IN VEGETABLE CELLS MEDIATED BY ALLELOCHEMICALS

    Directory of Open Access Journals (Sweden)

    Gustavo Dias de Almeida

    2008-06-01

    Full Text Available A alelopatia é uma interação entre dois organismos, onde um componente é afetado e o outro permanece estável. Esta interação pode ser fonte de descobertas para novos compostos fitotóxicos naturais com baixa toxicidade aos organismos não alvos de controle. A maior parte dos aleloquímicos são metabólitos secundários como os terpenóides, compostos fenólicos e ácido cianídrico, entre outros. A atuação dos aleloquímicos é variada e afeta um grande número de reações bioquímicas, resultando em diferentes modificações fisiológicas nas plantas, como na atividade enzimática, divisão e estrutura de células, permeabilidade das membranas e captação de íons, culminado na redução ou inativação da germinação e crescimento das plantas. Efeitos dos aleloquímicos sobre a fotossíntese e respiração tem sido melhor caracterizados, embora vários trabalhos tenham demonstrado a atuação desses compostos no estresse oxidativo, resultando em um aumento da produção de espécies reativas de oxigênio, os quais em concentrações elevadas são danosos às células. Dessa forma, o conhecimento dos mecanismos de atuação dos aleloquímicos é necessário para o desenvolvimento de técnicas de manejo sustentável na agricultura.Allelopathy is an interaction among two organisms, where one of that is affected and the other stays stable. It can be source for discoveries of new natural phytotoxic compounds with low toxicity to the organisms that are not target of control. Most of the allelochemicals are secondary metabolites like terpenoids, phenolic compounds, organic cyanides and longchain fatty acids. The performance of the allelochemicals can be different according the situations, and it affects a great number of biochemical reactions, resulting in different physiologic modifications in the plants. Allelochemicals could affect different pathways, like, the enzymatic activity, division and structure of cells, permeability of the

  2. Chemical stress induced by heliotrope (Heliotropium europaeum L.) allelochemicals and increased activity of antioxidant enzymes.

    Science.gov (United States)

    Abdulghader, Kalantar; Nojavan, Majid; Naghshbandi, Nabat

    2008-03-15

    The aims of this study were to evaluate the allelopathic potential of heliotrope on some biochemical processes of dodder. The preliminary experiments revealed that the effect of aqueous extract of leaves of heliotrope is higher than its seeds and roots. So, the aqueous extract of leaves was used in remaining experiments. Leaf extracts of 5 g powder per 100 mL H2O inhibited the germination of dodder seeds up to 95% and that of radish up to 100%. While, the aqueous extract of vine leaves which is a non-allelopathic plant did not have any inhibitory effect on these seeds. Vine leaf was used as a control to show that the inhibitory effect of heliotrope is due to an inhibitory compound but not due to the concentration. The leaf extract of heliotrope at 0.0, 0.1, 1.0, 2, 3, 4 and 5 g powder per 100 mL H2O reduced the radish seedling growth from 14 cm to about 0.5 cm and that of dodder from 7.5 cm to about 0.25 cm. The effects of heliotrope allelochemicals on some physiological and biochemical processes of radish was also Investigated. The activity of auxin oxidase increased in leaves and roots of radish. Suggesting that the reduced radish growth is due to the decreased active auxin levels in its leaves and roots. The activity of alpha-amylase was reduced, so reduction of starch degradation and lack of respiratory energy is the prime reason of germination inhibition in dodder and radish seeds. The level of soluble sugars increased. This is an indication of reduction of the activity of some respiratory enzymes and reduced consumption of these sugars. Proline levels were also increased, indicating that, the chemical stress is induced by leaf extract. Finally, the activities of GPX and CAT which are antioxidant enzymes were increased, along with increased extract concentration. These finding shows that the chemical stress induced by leaf extract produces super oxide (O2*) and H2O2, which is neutralized to H2O and O2 by these enzymes.

  3. Influence ofAmaranthus hybridus L. allelochemics on oviposition behavior ofSpodoptera exigua andS. eridania (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Mitchell, E R; Heath, R R

    1985-05-01

    Common pigweed,Amaranthus hybridus L., is a favorite host of the beet army worm (BAW),Spodoptera exigua L. Chemicals extracted from homogenized pigweed with distilled water, ethanol, or dichloromethane and sprayed back on pigweed deterred oviposition by the BAW. Similarly, water extracts of frass from conspecific larvae or southern armyworm (SAW) larvae,S. eridania (Cramer), fed pigweed leaves and sprayed back on pigweed plants also deterred BAW oviposition, thus confirming that deterrence was due to plant allelochemics rather than specific compounds associated with the metabolic or excretory products of the larvae. Confirmation of the presence of oviposition-deterring chemicals in pigweed was used to explain a previously observed seasonal displacement of BAW by SAW on pigweed in the field.

  4. Dissolved Organic Matter (DOM) From Different Composts: Comparative Study Of Properties And Allelochemical Effects On Horticultural Plants

    Science.gov (United States)

    Traversa, A.; Loffredo, E.; Gattullo, C. E.; Senesi, N.

    2009-04-01

    Dissolved organic matter (DOM) from compost has a major role in numerous chemical and biological processes occurring in the bulk substrate or compost amended soil, and can exert allelochemical effects on plant germination and growth. The objectives of this study were: (i) to investigate comparatively the main properties of three DOM fractions isolated from a green compost (DOMGC), a mixed compost (DOMMC) and a green coffee compost (DOMGCC), and (ii) to evaluate their allelochemical effects on the germination and early growth of two horticultural plants of worldwide interest such as tomato and lettuce. The DOM was extracted from each compost with distilled water (1/10 w/v) under mechanical shaking for 15 min. The suspension was then centrifuged at 6000 rpm for 15 min and filtered sequentially through filters with decreasing particle size retention (from 11 to 0.45 μm). Each DOM sample was characterized by means of pH, electrical conductivity, total organic carbon (TOC), E4/E6 ratio, fluorescence and FT IR spectroscopies and HPLC analysis. Comparative evaluation of the three DOM samples indicated the occurrence of significant differences among them. In particular, the pH value was similar and close to neutrality for DOMMC and DOMGC, whereas it resulted alkaline (pH 8.3) for DOMGCC. The EC values were also similar (about 3.2 mS/cm) for DOMMC and DOMGC and almost half value for DOMGCC. The TOC content, the E4/E6 ratio, the ɛ280 value and the humification index followed the same order: DOMGCC>DOMMC>DOMGC. The fluorescence analysis of the three DOM samples showed the presence of a common fluorophore unit associated to simple aromatic units such as phenolic-like, hydroxy-substituted benzoic and cinnamic acid derivatives. The peak wavelengths observed in the fluorescence emission, excitation and synchronous scan spectra of DOMGCC were generally higher than those of the two other DOM samples, which can be ascribed to a more extended aromatic system of the former. The FT

  5. Soil microorganisms alleviate the allelochemical effects of a thyme monoterpene on the performance of an associated grass species.

    Science.gov (United States)

    Ehlers, Bodil K

    2011-01-01

    Plant allelochemicals released into the soil can significantly impact the performance of associated plant species thereby affecting their competitive ability. Soil microbes can potentially affect the interaction between plant and plant chemicals by degrading the allelochemicals. However, most often plant-plant chemical interactions are studied using filter paper bioassays examining the pair-wise interaction between a plant and a plant chemical, not taking into account the potential role of soil microorganisms. To explore if the allelopathic effects on a grass by the common thyme monoterpene "carvacrol" are affected by soil microorganisms. Seedlings of the grass Agrostis capillaris originating from 3 different thyme sites were raised in the greenhouse. Seedlings were grown under four different soil treatments in a 2*2 fully factorial experiment. The monoterpene carvacrol was either added to standard greenhouse soil or left out, and soil was either sterilized (no soil microorganisms) or not (soil microorganisms present in soil). The presence of carvacrol in the soil strongly increased mortality of Agrostis plants, and this increase was highest on sterile soil. Plant biomass was reduced on soil amended with carvacrol, but only when the soil was also sterilized. Plants originating from sites where thyme produces essential oils containing mostly carvacrol had higher survival on soil treated with that monoterpene than plants originating from a site where thyme produced different types of terpenes, suggesting an adaptive response to the locally occurring terpene. The study shows that presence of soil microorganisms can alleviate the negative effect of a common thyme monoterpene on the performance of an associated plant species, emphasizing the role of soil microbes in modulating plant-plant chemical interactions.

  6. Soil microorganisms alleviate the allelochemical effects of a thyme monoterpene on the performance of an associated grass species.

    Directory of Open Access Journals (Sweden)

    Bodil K Ehlers

    Full Text Available Plant allelochemicals released into the soil can significantly impact the performance of associated plant species thereby affecting their competitive ability. Soil microbes can potentially affect the interaction between plant and plant chemicals by degrading the allelochemicals. However, most often plant-plant chemical interactions are studied using filter paper bioassays examining the pair-wise interaction between a plant and a plant chemical, not taking into account the potential role of soil microorganisms.To explore if the allelopathic effects on a grass by the common thyme monoterpene "carvacrol" are affected by soil microorganisms. Seedlings of the grass Agrostis capillaris originating from 3 different thyme sites were raised in the greenhouse. Seedlings were grown under four different soil treatments in a 2*2 fully factorial experiment. The monoterpene carvacrol was either added to standard greenhouse soil or left out, and soil was either sterilized (no soil microorganisms or not (soil microorganisms present in soil. The presence of carvacrol in the soil strongly increased mortality of Agrostis plants, and this increase was highest on sterile soil. Plant biomass was reduced on soil amended with carvacrol, but only when the soil was also sterilized. Plants originating from sites where thyme produces essential oils containing mostly carvacrol had higher survival on soil treated with that monoterpene than plants originating from a site where thyme produced different types of terpenes, suggesting an adaptive response to the locally occurring terpene.The study shows that presence of soil microorganisms can alleviate the negative effect of a common thyme monoterpene on the performance of an associated plant species, emphasizing the role of soil microbes in modulating plant-plant chemical interactions.

  7. Soil Microorganisms Alleviate the Allelochemical Effects of a Thyme Monoterpene on the Performance of an Associated Grass Species

    Science.gov (United States)

    Ehlers, Bodil K.

    2011-01-01

    Background Plant allelochemicals released into the soil can significantly impact the performance of associated plant species thereby affecting their competitive ability. Soil microbes can potentially affect the interaction between plant and plant chemicals by degrading the allelochemicals. However, most often plant-plant chemical interactions are studied using filter paper bioassays examining the pair-wise interaction between a plant and a plant chemical, not taking into account the potential role of soil microorganisms. Methodology/Principal findings To explore if the allelopathic effects on a grass by the common thyme monoterpene “carvacrol” are affected by soil microorganisms. Seedlings of the grass Agrostis capillaris originating from 3 different thyme sites were raised in the greenhouse. Seedlings were grown under four different soil treatments in a 2*2 fully factorial experiment. The monoterpene carvacrol was either added to standard greenhouse soil or left out, and soil was either sterilized (no soil microorganisms) or not (soil microorganisms present in soil). The presence of carvacrol in the soil strongly increased mortality of Agrostis plants, and this increase was highest on sterile soil. Plant biomass was reduced on soil amended with carvacrol, but only when the soil was also sterilized. Plants originating from sites where thyme produces essential oils containing mostly carvacrol had higher survival on soil treated with that monoterpene than plants originating from a site where thyme produced different types of terpenes, suggesting an adaptive response to the locally occurring terpene. Conclusions/Significance The study shows that presence of soil microorganisms can alleviate the negative effect of a common thyme monoterpene on the performance of an associated plant species, emphasizing the role of soil microbes in modulating plant-plant chemical interactions. PMID:22125596

  8. Identification and Characterization of CYP9A40 from the Tobacco Cutworm Moth (Spodoptera litura), a Cytochrome P450 Gene Induced by Plant Allelochemicals and Insecticides

    Science.gov (United States)

    Wang, Rui-Long; Staehelin, Christian; Xia, Qing-Qing; Su, Yi-Juan; Zeng, Ren-Sen

    2015-01-01

    Cytochrome P450 monooxygenases (P450s) of insects play crucial roles in the metabolism of endogenous and dietary compounds. Tobacco cutworm moth (Spodoptera litura), an important agricultural pest, causes severe yield losses in many crops. In this study, we identified CYP9A40, a novel P450 gene of S. litura, and investigated its expression profile and potential role in detoxification of plant allelochemicals and insecticides. The cDNA contains an open reading frame encoding 529 amino acid residues. CYP9A40 transcripts were found to be accumulated during various development stages of S. litura and were highest in fifth and sixth instar larvae. CYP9A40 was mainly expressed in the midgut and fat body. Larval consumption of xenobiotics, namely plant allelochemicals (quercetin and cinnamic acid) and insecticides (deltamethrin and methoxyfenozide) induced accumulation of CYP9A40 transcripts in the midgut and fat body. Injection of dsCYP9A40 (silencing of CYP9A40 by RNA interference) significantly increased the susceptibility of S. litura larvae to the tested plant allelochemicals and insecticides. These results indicate that CYP9A40 expression in S. litura is related to consumption of xenobiotics and suggest that CYP9A40 is involved in detoxification of these compounds. PMID:26393579

  9. The garlic allelochemical diallyl disulfide affects tomato root growth by influencing cell division, phytohormone balance and expansin gene expression

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    Fang Cheng

    2016-08-01

    Full Text Available Diallyl disulfide (DADS is a volatile organosulfur compound derived from garlic (Allium sativum L., and it is known as an allelochemical responsible for the strong allelopathic potential of garlic. The anticancer properties of DADS have been studied in experimental animals and various types of cancer cells, but to date, little is known about its mode of action as an allelochemical at the cytological level. The current research presents further studies on the effects of DADS on tomato (Solanum lycopersicum L. seed germination, root growth, mitotic index and cell size in root meristem, as well as the phytohormone levels and expression profile of auxin biosynthesis genes (FZYs, auxin transport genes (SlPINs and expansin genes (EXPs in tomato root. The results showed a biphasic, dose-dependent effect on tomato seed germination and root growth under different DADS concentrations. Lower concentrations (0.01-0.62 mM of DADS significantly promoted root growth, whereas higher levels (6.20-20.67 mM showed inhibitory effects. Cytological observations showed that the cell length of root meristem was increased and that the mitotic activity of meristematic cells in seedling root tips was enhanced at lower concentrations of DADS. In contrast, DADS at higher concentrations inhibited root growth by affecting both the length and division activity of meristematic cells. However, the cell width of the root meristem was not affected. Additionally, DADS increased the IAA and ZR contents of seedling roots in a dose-dependent manner. The influence on IAA content may be mediated by the up-regulation of FZYs and PINs. Further investigation into the underlying mechanism revealed that the expression levels of tomato EXPs were significantly affected by DADS. The expression levels of EXPB2 and beta-expansin precursor were increased after 3 d, and those of EXP1, EXPB3 and EXLB1 were increased after 5 d of DADS treatment (0.41 mM. This result suggests that tomato root growth

  10. Allelochemical effects of volatile compounds and organic extracts from Muscodor yucatanensis, a tropical endophytic fungus from Bursera simaruba.

    Science.gov (United States)

    Macías-Rubalcava, Martha L; Hernández-Bautista, Blanca E; Oropeza, Fabiola; Duarte, Georgina; González, María C; Glenn, Anthony E; Hanlin, Richard T; Anaya, Ana Luisa

    2010-10-01

    Muscodor yucatanensis, an endophytic fungus, was isolated from the leaves of Bursera simaruba (Burseraceae) in a dry, semideciduous tropical forest in the Ecological Reserve El Eden, Quintana Roo, Mexico. We tested the mixture of volatile organic compounds (VOCs) produced by M. yucatanensis for allelochemical effects against other endophytic fungi, phytopathogenic fungi and fungoids, and plants. VOCs were lethal to Guignardia mangifera, Colletotrichum sp., Phomopsis sp., Alternaria solani, Rhizoctonia sp., Phytophthora capsici, and P. parasitica, but had no effect on Fusarium oxysporum, Xylaria sp., the endophytic isolate 120, or M. yucatanensis. VOCs inhibited root elongation in amaranth, tomato, and barnyard grass, particularly those produced during the first 15 days of fungal growth. VOCs were identified by gas chromatography/mass spectrometry and included compounds not previously reported from other Muscodor species and the previously reported compounds octane, 2-methyl butyl acetate, 2-pentyl furan, caryophyllene, and aromadendrene. We also evaluated organic extracts from the culture medium and mycelium of M. yucatanensis on the same endophytes, phytopathogens, and plants. In general, extracts inhibited plants more than endophytic or phytopathogens fungi. G. mangifera was the only organism that was significantly stimulated by both extracts regardless of concentration. Compounds in both organic extracts were identified by gas chromatography/mass spectrometry. We discuss the possible allelopathic role that metabolites of M. yucatanensis play in its ecological interactions with its host plant and other organisms.

  11. Evaluating the effects of allelochemical ferulic acid on Microcystis aeruginosa by pulse-amplitude-modulated (PAM) fluorometry and flow cytometry.

    Science.gov (United States)

    Wang, Rui; Hua, Ming; Yu, Yang; Zhang, Min; Xian, Qi-Ming; Yin, Da-Qiang

    2016-03-01

    We investigated the effects of allelochemical ferulic acid (FA) on a series of physiological and biochemical processes of blue-green algae Microcystis aeruginosa, in order to find sensitive diagnostic variables for allelopathic effects. Algal cell density was significantly suppressed by FA (0.31-5.17 mM) only after 48 h exposure. Inhibitions of photosynthetic parameters (F(v)/F(m) and F(v)'/F(m)') occurred more rapidly than cell growth, and the stimulation of non-photochemical quenching was observed as a feed-back mechanisms induced by photosystem II blockage, determining by PAM fluorometry. Inhibitions on esterase activity, membrane potential and integrity, as well as disturbance on cell size, were all detected by flow cytometry with specific fluorescent markers, although exhibiting varied sensitivities. Membrane potential and esterase activity were identified as the most sensitive parameters (with relatively lower EC50 values), and responded more rapidly (significantly inhibited only after 8 h exposure) than photosynthetic parameters and cell growth, thus may be the primary responses of cyanobacteria to FA exposure. The use of PAM fluorometry and flow cytometry for rapid assessment of those sensitive variables may contribute to future mechanistic studies of allolepathic effects on phytoplankton. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Sensitivity of the green alga Pediastrum duplex Meyen to allelochemicals is strain-specific and not related to co-occurrence with allelopathic macrophytes.

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    Falk Eigemann

    Full Text Available Interspecific differences in the response of microalgae to stress have numerous ecological implications. However, little is known of intraspecific sensitivities and the potential role of local genetic adaptation of populations. We compared the allelochemical sensitivity of 23 Pediastrum duplex Meyen strains, a common component of the freshwater phytoplankton. In order to test for local genetic adaptation, strains were isolated from water bodies with and without the allelopathically-active submerged macrophyte Myriophyllum. Strains were assigned to P. duplex on the basis of cell shape and colony morphology and only P. duplex strains that belonged to the same lineage in an ITS rDNA phylogeny were used. Inhibition of strain growth rates and maximum quantum yields of photosystem II were measured after exposure to tannic acid (TA and co-culture with Myriophyllum spicatum. Growth rate inhibition varied over one order of magnitude between the P. duplex strains. There was no correlation between the presence of Myriophyllum in the source location and the sensitivity of the strains to TA or the presence of Myriophyllum, suggesting that at least strong unidirectional local adaptation to Myriophyllum had not taken place in the studied water bodies. The maximum quantum yield of photosystem II of TA exposed algae decreased, whereas the yield of algae exposed to M. spicatum was slightly higher than that of the controls. The ranking of P. duplex strain sensitivities differed between the types of exposure (single additions of TA versus co-existence with M. spicatum and the parameter measured (growth rate versus maximum quantum yield, emphasizing the importance of measuring multiple traits when analysing strain-specific sensitivities towards allelochemicals. The observation that sensitivities to allelochemicals vary widely among strains of a single freshwater algal species should be taken into account if evaluating ecological consequences of allelopathic

  13. Allelochemicals in rye (Secale cereale L.): cultivar and tissue differences in the production of benzoxazinoids and phenolic acids.

    Science.gov (United States)

    Carlsen, Sandra C K; Kudsk, Per; Laursen, Bente; Mathiassen, Solvejg K; Mortensen, Anne G; Fomsgaard, Inge S

    2009-02-01

    In the present study, a range of benzoxazinoid compounds and phenolic acids, all known to be allelochemicals of rye, were identified and quantified in 13 rye cultivars grown at three different localities. Plant samples were collected in the spring at the time when an autumn-sown rye cover crop would be incorporated into the soil. Significant variations in content among shoots and roots were seen for all of the secondary metabolites, with non-methoxy-substituted benzoxazinoids (BX) dominating the shoots, whereas comparable levels were found in the concentrations of BX and methoxy-substituted benzoxazinoids (MBX) in the roots. This distribution of compounds may indicate different biosynthetic pathways and/or different mechanisms of action of these compounds. Concentrations not only depended on plant part, but also on the geographical location--with differences in contents of up to a factor of 5. These differences can probably be attributed to differences in growing conditions. The variation among cultivars was similar to that among geographical localities, with differences within localities of up to a factor of 7 in the shoots and a factor of 14 in the roots. In roots, the contents of the four phenolic acids and the benzoxazinoid 6-methoxybenzoxazolin-2-one (MBOA) were correlated. In shoots, the contents of the two benzoic acids were correlated with each other, whereas the two cinnamic acids were correlated with MBOA and several other benzoxazinoids. The lack of correlation between MBOA and all other benzoxazinoids in the roots of rye might indicate that a hitherto unknown synthetic pathway exists for MBOA. The genes responsible for the synthesis of some of the benzoxazinoids have never been identified, and further gene expression studies are required to assess the observed correlation between the concentration of these compounds and other benzoxazinoids for which the responsible genes are known. The present study revealed a potential for breeding rye cultivars with

  14. Allelopathy in the natural and agricultural ecosystems and isolation of potent allelochemicals from Velvet bean (Mucuna pruriens) and Hairy vetch (Vicia villosa).

    Science.gov (United States)

    Fujii, Yoshiharu

    2003-06-01

    We have studied on allelopathy of plants and developed methods to identify the effective substances in root exudates, leaf leacheate, and volatile chemicals emitted from plants. We found traditional cover plants that show allelopathic activity are useful for weed control. It could eliminate the use of synthetic chemicals for this purpose. Allelopathy is a natural power of plants to protect themselves by producing natural organic chemicals. Some endemic plants in Asia, already known by farmers in the region, as either cover crops used in intercropping, hedgerow, or agroforestry, were found to possess strong allelopathic abilities. Our group identified several allelochemicals from these plants. These allelopathic cover crops, mostly leguminous plants, provide protein rich food, and grow easily without artificial fertilizers, herbicides, insecticides and fungicides. In this regards, these allelopathic cover crops could save food shortage in rural area, and are useful for environmental conservation. Screenings of allelopathic plants by specific bioassays and field tests have been conducted. Hairy vetch (Vicia villosa) and Velvet bean (Mucuna pruriens) are two promising species for the practical application of allelopathy. An amino acid, L-DOPA, unusual in plants, plays an important role as allelochemical in Velvet bean (Mucuna pruriens). Hairy vetch is the most promising cover plant for the weed control in orchard, vegetable and rice production and even for landscape amendment in abandoned field in Japan. We have isolated "cyanamide", a well known nitrogen fertilizer, from Hairy vetch. This is the first finding of naturally produced cyanamide in the world.

  15. Nepenthes insignis uses a C2-portion of the carbon skeleton of L-alanine acquired via its carnivorous organs, to build up the allelochemical plumbagin.

    Science.gov (United States)

    Rischer, Heiko; Hamm, Andreas; Bringmann, Gerhard

    2002-03-01

    Tropical pitcher plants (Nepenthes) catch animals in their specialized cup-shaped leaves, digest the prey by secreting enzymes, and actively take up the resulting compounds. The benefit of this behaviour is the ability to grow and compete in nutrient-poor habitats. Our present in vitro study shows that not only the nitrogen of alanine fed to the carnivorous organs is used by the plant but that in addition intact C2-units derived from C-2 and C-3 of stable isotope labelled L-alanine serve as building blocks, here exemplarily for the synthesis of the secondary metabolite plumbagin, a potent allelochemical. This result adds a new facet to the benefit of carnivory for plants. The availability of plumbagin by a de novo synthesis probably enhances the plants' fitness in their defence against phytophagous and pathogenic organisms. A missing specific uptake or CoA activation mechanism might be the reason that acetate fed to the pitchers was not incorporated into the naphthoquinone plumbagin. The dihydronaphthoquinone glucosides rossoliside and plumbaside A, here isolated for the first time from Nepenthes, by contrast, showed no incorporation after feeding of any of the two precursors, suggesting these compounds to be storage forms with probably very low turnover rates.

  16. Allelopathic activity of Leonurus siribicus L. on seed germination and seedling growth of wheat and identification of 4- hydroxy benzoic acid as an allelochemical by chromatography

    International Nuclear Information System (INIS)

    Sayed, M. A.; Imam, R.; Siddiqui, M.N.

    2016-01-01

    The aim of this study was to investigate the allelopathic effects of L. siribicus extract on seed germination and seedlings growth of wheat as well as to identify potential allelochemical. The different concentration (5, 10 and 15%) of aqueous extract were applied during the time of sowing and at 5 days after sowing of wheat seed. L. siribicus extract showed concentration and time - depending activity. Different concentration of aqueous extract inhibited seed germination, seedlings growth, when extracts were applied during the time of seed sowing. The stimulatory effect of seedlings growth were found for 5 % aqueous extract, in contrast 10 and 15% extract inhibited seedlings growth, when extracts were applied at 5 days after sowing. Apart from, 4-hydroxy benzoic acids affected seedlings growth irrespective of application time. The weight of dry matter of wheat seedlings were increased for 5% than 10 and 15% extracts. Thin layer chromatography suggested that the presence of 4-hydroxy benzoic acid including other allelopathic and growth regulatory compounds inhibited germination and seedlings growth. Mineral composition was determined and its might have some stimulatory effect on seedlings growth. It was interesting that 5% extract inhibited germination and seedlings growth, when it was applied during the time of seed sowing, but stimulated seedling growth, when it was applied at 5 days after sowing. The extract of this plants can be used either for bioherbicide as well as growth stimulatory agents for the organic farming system. To find out molecular mechanism behind it, further research is to be done. (author)

  17. Root-secreted allelochemical in the noxious weed Phragmites australis deploys a reactive oxygen species response and microtubule assembly disruption to execute rhizotoxicity.

    Science.gov (United States)

    Rudrappa, Thimmaraju; Bonsall, Justin; Gallagher, John L; Seliskar, Denise M; Bais, Harsh P

    2007-10-01

    Phragmites australis is considered the most invasive plant in marsh and wetland communities in the eastern United States. Although allelopathy has been considered as a possible displacing mechanism in P. australis, there has been minimal success in characterizing the responsible allelochemical. We tested the occurrence of root-derived allelopathy in the invasiveness of P. australis. To this end, root exudates of two P. australis genotypes, BB (native) and P38 (an exotic) were tested for phytotoxicity on different plant species. The treatment of the susceptible plants with P. australis root exudates resulted in acute rhizotoxicity. It is interesting to note that the root exudates of P38 were more effective in causing root death in susceptible plants compared to the native BB exudates. The active ingredient in the P. australis exudates was identified as 3,4,5-trihydroxybenzoic acid (gallic acid). We tested the phytotoxic efficacy of gallic acid on various plant systems, including the model plant Arabidopsis thaliana. Most tested plants succumbed to the gallic acid treatment with the exception of P. australis itself. Mechanistically, gallic acid treatment generated elevated levels of reactive oxygen species (ROS) in the treated plant roots. Furthermore, the triggered ROS mediated the disruption of the root architecture of the susceptible plants by damaging the microtubule assembly. The study also highlights the persistence of the exuded gallic acid in P. australis's rhizosphere and its inhibitory effects against A. thaliana in the soil. In addition, gallic acid demonstrated an inhibitory effect on Spartina alterniflora, one of the salt marsh species it successfully invades.

  18. Potential allelochemicals from Sambucus nigra.

    Science.gov (United States)

    D'Abrosca, B; DellaGreca, M; Fiorentino, A; Monaco, P; Previtera, L; Simonet, A M; Zarrelli, A

    2001-12-01

    Twenty-four aromatic metabolites belonging to cyanogenins, lignans, flavonoids, and phenolic glycosides were obtained from Sambucus nigra. Structures were determined on the basis of their spectroscopic features. Two compounds have been isolated and identified as (2S)-2-O-beta-D-glucopyranosyl-2-hydroxyphenylacetic acid and benzyl 2-O-beta-D-glucopyranosyl-2,6-dihydroxybenzoate. All the compounds have been assayed on dicotyledons Lactuca sativa (lettuce) and Raphanus sativus (radish) and monocotyledon Allium cepa (onion) to test their stimulatory or inhibitory effects on seed germination and radicle elongation. Cyanogenins have a mainly inhibiting effect while lignans stimulate the growth. Some compounds show different effects on dicotyledons and monocotyledons.

  19. Toxicidade para lagartas de Phthorimaea operculella (Zell. dos aleloquímicos 2-tridecanona e 2-undecanona presentes em tomateiro (Lycopersicon spp. Toxicity of 2-tridecanone and 2-undecanone allelochemicals present in tomato (Lycopersicon spp. for Phthorimaea operculella (Zell. larvae

    Directory of Open Access Journals (Sweden)

    M.U. Ventura

    1995-12-01

    Full Text Available Avaliou-se a toxicidade para Phthorimaea operculella (Zell. dos aleloquímicos 2-trídecanona e 2-undecanona, presentes nos exsudatos glandulares dos tricomas de Lycopersicon spp. Determinou-se a toxicidade dos exsudatos de L. hirsutum f. glabratum PI134417 (DL50, do 2-tridecanona (dose letal: DL50 e concentração letal: CL50 e do 2-undecanona (CL50 para lagartas de primeiro ínstar desse inseto. A DL50 foi de 5,54 glândulas e 775,53 ng por lagarta, respectivamente. Em relação à concentração letal, o 2-tridecanona foi mais tóxico do que o 2-undecanona. A toxicidade (CL50 do 2-tridecanona aumentou com a elevação da temperatura de 27 para 32°C e para o 2-undecanona ocorreu o inverso. Concluiu-se que estes compostos podem ter grande importância na resistência do tomateiro para esta praga.This research deals with the toxicity of 2-tridecanone and 2-undecanone allelochemicals, present in the grandular trichomes of Lycopersicon spp., to Phthorimaea operculella (Zell.. The toxicity of the exsudates of L. hirsutum f. glabratum PI 134117 (LD50, of the 2-tridecanone (lethal dose: LD50and lethal concentration: LC50 and 2-undecanone (LC50 to first instar larvae of this pest were determined. The LD50value was 5.54 glands and 775.53 ng per larvae, respectively. With respect to the lethal concentration, the 2-tridecanone was more toxic than the 2-undecanone. The toxicity (CL50 of the 2-tridecanone increased with the elevation of the temperature from 27 to 32°C, but decreased with the 2-undecanone. It was concluded that these compounds can have great importance in the resistance of the tomato plant to this pest.

  20. Physiological conjunction of allelochemicals and desert plants.

    Science.gov (United States)

    Yosef Friedjung, Avital; Choudhary, Sikander Pal; Dudai, Nativ; Rachmilevitch, Shimon

    2013-01-01

    Plants exchange signals with other physical and biological entities in their habitat, a form of communication termed allelopathy. The underlying principles of allelopathy and secondary-metabolite production are still poorly understood, especially in desert plants. The coordination and role of secondary metabolites were examined as a cause of allelopathy in plants thriving under arid and semiarid soil conditions. Desert plant species, Origanum dayi, Artemisia sieberi and Artemisia judaica from two different sources (cultivar cuttings and wild seeds) were studied in their natural habitats. Growth rate, relative water content, osmotic potential, photochemical efficiency, volatile composition and vital factors of allelopathy were analyzed at regular intervals along four seasons with winter showing optimum soil water content and summer showing water deficit conditions. A comprehensive analysis of the volatile composition of the leaves, ambient air and soil in the biological niche of the plants under study was carried out to determine the effects of soil water conditions and sample plants on the surrounding flora. Significant morpho-physiological changes were observed across the seasons and along different soil water content. Metabolic analysis showed that water deficit was the key for driving selective metabolomic shifts. A. judaica showed the least metabolic shifts, while A. sieberi showed the highest shifts. All the species exhibited high allelopathic effects; A. judaica displayed relatively higher growth-inhibition effects, while O. dayi showed comparatively higher germination-inhibition effects in germination assays. The current study may help in understanding plant behavior, mechanisms underlying secondary-metabolite production in water deficit conditions and metabolite-physiological interrelationship with allelopathy in desert plants, and can help cull economic benefits from the produced volatiles.

  1. Physiological conjunction of allelochemicals and desert plants.

    Directory of Open Access Journals (Sweden)

    Avital Yosef Friedjung

    Full Text Available Plants exchange signals with other physical and biological entities in their habitat, a form of communication termed allelopathy. The underlying principles of allelopathy and secondary-metabolite production are still poorly understood, especially in desert plants. The coordination and role of secondary metabolites were examined as a cause of allelopathy in plants thriving under arid and semiarid soil conditions. Desert plant species, Origanum dayi, Artemisia sieberi and Artemisia judaica from two different sources (cultivar cuttings and wild seeds were studied in their natural habitats. Growth rate, relative water content, osmotic potential, photochemical efficiency, volatile composition and vital factors of allelopathy were analyzed at regular intervals along four seasons with winter showing optimum soil water content and summer showing water deficit conditions. A comprehensive analysis of the volatile composition of the leaves, ambient air and soil in the biological niche of the plants under study was carried out to determine the effects of soil water conditions and sample plants on the surrounding flora. Significant morpho-physiological changes were observed across the seasons and along different soil water content. Metabolic analysis showed that water deficit was the key for driving selective metabolomic shifts. A. judaica showed the least metabolic shifts, while A. sieberi showed the highest shifts. All the species exhibited high allelopathic effects; A. judaica displayed relatively higher growth-inhibition effects, while O. dayi showed comparatively higher germination-inhibition effects in germination assays. The current study may help in understanding plant behavior, mechanisms underlying secondary-metabolite production in water deficit conditions and metabolite-physiological interrelationship with allelopathy in desert plants, and can help cull economic benefits from the produced volatiles.

  2. Identification of Allelochemicals from Terminalia Chebula

    African Journals Online (AJOL)

    Nekky Umera

    allochemicals than the bark and were more inhibitory to seeding ... water (1:1) 5 times. The aqueous solution was saved and it was extracted with equal volume of ethanol: ethyl acetate (1:1) for 5 times. The resulting ethanol: ethyl acetate solution was ... The inhibitory effect on the seed germination by leaf aqueous extracts.

  3. Proposta metodológica para análise da ocorrência de sinergismo e efeitos potencializadores entre aleloquímicos Methodological proposal for analysis of synergism and potentializing effects among allelochemicals

    Directory of Open Access Journals (Sweden)

    A.P.S. Souza Filho

    2006-09-01

    Full Text Available Os procedimentos envolvendo a análise de sinergismo entre aleloquímicos têm envolvido, basicamente, a utilização de concentrações fixas. Neste trabalho, propõe-se um modelo teórico envolvendo quatro possibilidades de respostas: uma que demonstra a existência de sinergismo (possibilidade A do modelo; outra que revela a inexistência de sinergismo (possibilidade B do modelo; e duas que revelam que uma substância potencializa o efeito de outra (possibilidades C e D do modelo. Para efeito de teste do modelo, utilizaram-se duas substâncias químicas (ácido 3,4,5-trimetoxibenzóico [S1] e ácido verátrico [S2] isoladas das folhas de Parkia pendula, com atividade alelopática já comprovada, nas seguintes proporções: S1 pura, S2 pura e combinações de S1 e S2, nas seguintes proporções: 3:1, 1:1 e 1:3. Como plantas indicadoras foram utilizadas as plantas daninhas malícia (Mimosa pudica e mata-pasto (Senna obtusifolia. Os resultados, analisados em relação às quatro possibilidades estabelecidas no modelo teórico, permitiram inferir a inexistência de efeitos sinérgicos entre as duas substâncias testadas. As variações entre os resultados obtidos e a possibilidade B do modelo podem ser atribuídas ao potencial inibitório da substância e à sensibilidade das espécies receptoras às substâncias testadas.The procedures involving the analysis of synergism between allelochemicals have basically involved the use of fixed concentrations. This work deals with theoretical model involving four possibilities of response: one demonstraing the existence of synergism (possibility A of the model; one demonstraing the absence of synergism (possibility B of the model and two showing that a substance potentializes the effect of another (possibilities C and D of the model. Two isolated chemical substances (3,4,5-trimetoxybenzoic acid [S1] and 3,4-dimetoxybenzoic acid [S2] were used to test the model, isolated from Parkia pendula leaves with

  4. Allelochemicals Effect of Aqueous Leachate from Oudneya Africana R

    African Journals Online (AJOL)

    nesrine

    2014-03-05

    Mar 5, 2014 ... This present study was conducted to investigate the possible allelopathic effect of Oudneya africana. (donor species) on Bromus tectorum (weed species) and Triticum aestivum (cv. Sahel1; crop species) through germination bioassay experiment. B. tectorum is a winter annual grass that grows in winter.

  5. Concentrations of the Allelochemical (+/-)-catechin IN Centaurea maculosa soils.

    Science.gov (United States)

    Perry, Laura G; Thelen, Giles C; Ridenour, Wendy M; Callaway, Ragan M; Paschke, Mark W; Vivanco, Jorge M

    2007-12-01

    The phytotoxin (+/-)-catechin has been proposed to mediate invasion and autoinhibition by the Eurasian plant Centaurea maculosa (spotted knapweed). The importance of (+/-)-catechin to C. maculosa ecology depends in part on whether sufficient catechin concentrations occur at appropriate times and locations within C. maculosa soil to influence neighboring plants. Previous research on catechin in C. maculosa soils has yielded conflicting results, with some studies finding high soil catechin concentrations and other, more recent studies finding little or no catechin in field soils. Here, we report the most extensive study of soil catechin concentrations to date. We examined soil catechin concentrations in 402 samples from 11 C. maculosa sites in North America sampled in consecutive months over 1 yr, excluding winter months. One site was sampled on seven dates, another was sampled twice, and the remaining nine sites were each sampled once on a range of sampling dates. Methods used were similar to those with which we previously measured high soil catechin concentrations. We detected catechin only in the site that was sampled on seven dates and only on one sampling date in that site (May 16 2006), but in all samples collected on that date. The mean soil catechin concentration on that date was 0.65 +/- 0.45 (SD) mg g(-1), comparable to previously reported high concentrations. There are a number of possible explanations for the infrequency with which we detected soil catechin in this work compared to previous studies. Differences in results could reflect spatial and temporal variation in catechin exudation or degradation, as we examined different sites in a different year from most previous studies. Also, large quantities of catechin were detected in blanks for two sampling periods in the present study, leading us to discard those data. This contamination suggests that previous reports of high catechin concentrations that did not include blanks should be viewed with caution. Our results suggest that pure catechin is only rarely present in C. maculosa bulk soils. Thus, although catechin may play a role in C. maculosa invasion, the infrequency of soil catechin that we determined in this study suggests that we cannot be as certain of its role as previous reports of high soil catechin concentrations suggested.

  6. Benzoxazinoid allelochemicals are absorbed and metabolized in mammals

    DEFF Research Database (Denmark)

    B. Adhikari, Khem; Laursen, Bente Birgitte; Lærke, Helle Nygaard

    2014-01-01

    and bakery products was recently identified, making them interesting compounds from a nutritional point of view. Rye grain is the major source of dietary benzoxazinoids followed by wheat. The objective of these studies was to evaluate the uptake, distribution and metabolism of dietary benzoxazinoids...

  7. The allelochemical MDCA inhibits lignification and affects auxin homeostasis

    Czech Academy of Sciences Publication Activity Database

    Steenackers, W.; Cesarino, I.; Klíma, Petr; Quareshy, M.; Vanholme, R.; Corneillie, S.; Kumpf, R. P.; Van De Wouwer, D.; Ljung, K.; Goeminne, G.; Novák, Ondřej; Zažímalová, Eva; Napier, R.; Boerjan, W.; Vanholme, B.

    2016-01-01

    Roč. 172, č. 2 (2016), s. 874-888 ISSN 0032-0889 R&D Projects: GA ČR(CZ) GA16-10948S; GA MŠk(CZ) LO1204 Grant - others:OPPK(XE) CZ.2.16/3.1.00/21519 Institutional support: RVO:61389030 Keywords : auxin biosynthesis * lignification * Asparagus officinalis Subject RIV: ED - Physiology Impact factor: 6.456, year: 2016

  8. Functional Characterization and Expression of Molluscan Detoxification Enzymes and Transporters Involved in Dietary Allelochemical Resistance

    Science.gov (United States)

    2008-06-01

    melanogasrer (43), and Homo sapiens (40) (Ding et al. 2003). To date, seven soluble cytosolic GST classes, encoding proteins of approximately 200 amino acids...Fasciola hepatica (P56598), Haliotis discus discus (ABF67506, ABF67507), Haemaphysalis longicornis (AAQ74441), Homo sapiens (NP_665683, AAV38750, NP_000840...MorciTa 2003 Mtilus Mdulis Western blot Jonsson ct al. 2004 CYP2H Mtilus go/lh,-ro/ii Western blot Peters el al. 19 9 0a (Y P2 Mvti/us ’dlis Western blot

  9. Cytochrome P450s from the fall armyworm (Spodoptera frugiperda): responses to plant allelochemicals and pesticides.

    Science.gov (United States)

    Giraudo, M; Hilliou, F; Fricaux, T; Audant, P; Feyereisen, R; Le Goff, G

    2015-02-01

    Spodoptera frugiperda is a polyphagous lepidopteran pest that encounters a wide range of toxic plant metabolites in its diet. The ability of this insect to adapt to its chemical environment might be explained by the action of major detoxification enzymes such as cytochrome P450s (or CYP). Forty-two sequences coding for P450s were identified and most of the transcripts were found to be expressed in the midgut, Malpighian tubules and fat body of S. frugiperda larvae. Relatively few P450s were expressed in the established cell line Sf9. In order to gain information on how these genes respond to different chemical compounds, larvae and Sf9 cells were exposed to plant secondary metabolites (indole, indole-3-carbinol, quercetin, 2-tridecanone and xanthotoxin), insecticides (deltamethrin, fipronil, methoprene, methoxyfenozide) or model inducers (clofibrate and phenobarbital). Several genes were induced by plant chemicals such as P450s from the 6B, 321A and 9A subfamilies. Only a few genes responded to insecticides, belonging principally to the CYP9A family. There was little overlap between the response in vivo measured in the midgut and the response in vitro in Sf9 cells. In addition, regulatory elements were detected in the promoter region of these genes. In conclusion, several P450s were identified that could potentially be involved in the adaptation of S. frugiperda to its chemical environment. © 2014 The Royal Entomological Society.

  10. The effect of carbon supply on allocation to allelochemicals and caterpillar consumption of peppermint.

    Science.gov (United States)

    Lincoln, D E; Couvet, D

    1989-01-01

    The carbon supply of peppermint plants was manipulated by growing clonal propagules under three carbon dioxide regimes (350, 500 and 650 μl l -1 ). Feeding by fourth instar caterpillars of Spodoptera eridania increased with elevated CO 2 hostplant regime, as well as with low leaf nitrogen content and by a high proportion of leaf volatile terpenoids. Leaf weight increased significantly with the increased carbon supply, but the amount of nitrogen per leaf did not change. The amount of volatile leaf mono-and sesquiterpenes increased proportionately with total leaf dry weight and hence was not influenced by CO 2 supply. These results are consistent with ecological hypotheses which assume that allocation to defense is closely regulated and not sensitive to carbon supply per se.

  11. Induction by carrot allelochemicals of insecticide-metabolising enzymes in the southern armyworm (Spodoptera eridania).

    Science.gov (United States)

    Brattsten, L B; Evans, C K; Bonetti, S; Zalkow, L H

    1984-01-01

    Carrot foliage monoterpenes induce cytochrome P-450 up to 2.9-fold, NADPH cytochrome c (P-450) reductase up to 1.6-fold, NADPH-oxidation up to 3.8-fold, aldrin epoxidation up to 1.5-fold in southern armyworm larval midgut tissues when incorporated in their diet at 0.2% for 3 days. Stigmasterol and ergosterol did not substantially induce microsomal oxidase activities and significantly inhibited GSH S-aryltransferase activity and sulfotransferase activity. Coumarin did not substantially affect microsomal oxidase and sulfotransferase activity but is the most potent inducer of GSH S-aryltransferase activity, increasing this activity 7-fold. None of the chemicals is acutely toxic to the sixth instar larvae or affect the larval weight gain except coumarin which significantly depressed the maximal body weight attained.

  12. Allelochemical Control of Non-Indigenous Invasive Plant Species Affecting Military Testing and Training Activities

    Science.gov (United States)

    2010-10-01

    exhibit resistance to flavonoids in knapweed root exudates and may serve as candidate species for management efforts. Because legumes form symbiotic...metabolite-related transcript, as this enzyme represents the first enzymatic step in the flavonoid synthesis pathway which contributes isoflavones...anthocyanins, condensed tannins and other secondary metabolic compounds in plants (La Camera et al. 2004; Treutter 2005; Winkel-Shirley 2001). Flavonoids

  13. Impact of azadirachtin, an insecticidal allelochemical from neem on soil microflora, enzyme and respiratory activities.

    Science.gov (United States)

    Gopal, Murali; Gupta, Alka; Arunachalam, V; Magu, S P

    2007-11-01

    The effect of 10% azadirachtin granules (alcoholic extract of neem seed kernel mixed with China clay) was studied on the population of bacteria, actinomycetes, fungi, Azotobacter and nitrifying bacteria; soil dehydrogenase, phosphatase and respiratory activities on 0, 15th, 30th, 60th and 90th days after application in sandy loam soil collected from the fields. It was observed that baring the Azotobacter sp., azadirachtin at all the doses exerted a suppressive effect on the rest of the microbial communities and enzyme activities in the initial 15 day period. The population of bacteria, actinomycetes besides phosphatase and respiratory activities recovered after 60th day and subsequently increased significantly. The fungi and nitrifiers were most sensitive groups as their numbers were reduced significantly throughout the studies. The two times and five times recommended dose of azadirachtin had very high biocidal effects on the soil microorganisms and its activities. However, analysis of the data by the Shannon Weaver index showed that azadirachtin reduces both the form and functional microbial diversity at all doses.

  14. Effects of 1,1-Dimethylpiperidinium Chloride on the Pests and Allelochemicals of Cotton and Pecan.

    Science.gov (United States)

    P. A. Hedin; J. N. Jenkins; J. C. McCarty; J. E. Mulrooney; W. L. Parrott; A. Borazjani; C. H. Graves; T. H. Filer

    1984-01-01

    The growth regulator, PIX (mepiquat chloride - 1,1-dimethyl-piperdinium chloride), when applied to cotton (Gossypium hirsutum L.) and pecan (Carya illinoensis Koch), caused internode shortening. PIX did not elicit an increase in resistance in cotton to the tobacco budworm (Heliothis virescens (Fab.)], or in pecan...

  15. Allelochemical regulation of reproduction and seed germination of two BrazilianBaccharis species by phytotoxic trichothecenes.

    Science.gov (United States)

    Kuti, J O; Jarvis, B B; Mokhtari-Rejali, N; Bean, G A

    1990-12-01

    The potent phytotoxic trichothecene roridins and baccharinoids occur naturally in the Brazilian plants,Baccharis coridifolia andB. megapotamica. Biosynthesis of roridins inB. coridifolia appears to be linked to pollination, and the phytotoxins then accumulate in the seed. The roles of the phytotoxins in pollination, seed maturation, and germination of theBaccharis species were investigated. The high production of roridins occurred only in seeds resulting from intraspecific pollination, and the concentration of the toxins in the seeds generally increased with seed maturity. Removal of seed coats from trichothecene-producing BrazilianBaccharis species (B. coridifolia andB. megapotamica) and non-trichothecene-producing AmericanBaccharis species (B. halimifolia andB. glutinosa) resulted in improved seed germination ofB. halimifolia andB. glutinosa but complete inhibition of seed germination ofB. coridifolia andB. megapotamica. Addition of seed coat extracts of the BrazilianBaccharis species of dilute solutions (10(-6)μg/ml) of roridins or baccharinoids to the decoated seeds ofB. coridifolia andB. megapotamica resulted in germination, while seeds ofB. halimifolia andB. glutinosa were killed by the phytotoxins. Roridins interacted with gibberellic acid, a germination promoter, but not with abscisic acid, a germination inhibitor. The results from this study suggest that macrocyclic trichothecenes have a regulatory role(s) on reproduction and germination of BrazilianBaccharis species in their natural habitat.

  16. Evaluation of putative allelochemicals in rice root exudates for their role in the suppression of arrowhead root growth.

    Science.gov (United States)

    Seal, Alexa N; Haig, Terry; Pratley, James E

    2004-08-01

    In previous studies, 15 putative allelopathic compounds detected in rice root exudates were quantified by GC/MS/MS. In this study, multiple regression analysis on these compounds determined that five selected phenolics, namely caffeic, p-hydroxybenzoic, vanillic, syringic, and p-coumaric acids, from rice exudates were best correlated with the observed allelopathic effect on arrowhead (Sagittaria montevidensis) root growth. Despite this positive association, determination of the phenolic acid dose-response curve established that the amount quantified in the exudates was much lower than the required threshold concentration for arrowhead inhibition. A similar dose-response curve resulted from a combination of all 15 quantified compounds. Significant differences between the amounts of trans-ferulic acid, abietic acid, and an indole also existed between allelopathic and non-allelopathic rice cultivars. The potential roles of these three compounds in rice allelopathy were examined by chemoassay. Overall, neither the addition of trans-ferulic acid nor 5-hydroxyindole-3-acetic acid to the phenolic mix significantly contributed to phytotoxicity, although at higher concentrations, trans-ferulic acid appeared to act antagonistically to the phytotoxic effects of the phenolic mix. The addition of abietic acid also decreased the inhibitory effect of the phenolic mix. These studies indicate that the compounds quantified are not directly responsible for the observed allelopathic response. It is possible that the amount of phenolic acids may be indirectly related to the chemicals finally responsible for the observed allelopathic effect.

  17. Coexistence via coevolution driven by reduced allelochemical effects and increased tolerance to competition between invasive and native plants.

    Science.gov (United States)

    Huang, Fangfang; Lankau, Richard; Peng, Shaolin

    2018-04-01

    Coevolution can promote long-term coexistence of two competing species if selection acts to reduce the fitness inequality between competitors and/or strengthen negative frequency dependence within each population. However, clear coevolution between plant competitors has been rarely documented. Plant invasions offer opportunities to capture the process of coevolution. Here we investigated how the developing relationship between an invasive forb, Alliaria petiolata, and a native competitor, Pilea pumila, may affect their long-term coexistence, by testing the competitive effects of populations of varying lengths of co-occurrence on each other across a chronosequence of invasion history. Alliaria petiolata and P. pumila tended to develop greater tolerance to competition over invasion history. Their coexistence was promoted more by increases in stabilizing relative to equalizing processes. These changes likely stem in part from reductions in allelopathic traits in the invader and evolution of tolerance in the native. These results suggested that some native species can evolve tolerance against the competitive effects of strong invaders, which likely promoted their persistence in invaded communities. However, the potential for coevolutionary rescue of competing populations is likely to vary across native species, and evolutionary processes should not be expected to compensate for the ecological consequences of exotic invasions. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  18. Allelochemicals Produced by Brown Macroalgae of the Lobophora Genus Are Active against Coral Larvae and Associated Bacteria, Supporting Pathogenic Shifts to Vibrio Dominance.

    Science.gov (United States)

    Morrow, Kathleen M; Bromhall, Katrina; Motti, Cherie A; Munn, Colin B; Bourne, David G

    2017-01-01

    Pervasive environmental stressors on coral reefs are attributed with shifting the competitive balance in favor of alternative dominants, such as macroalgae. Previous studies have demonstrated that macroalgae compete with corals via a number of mechanisms, including the production of potent primary and secondary metabolites that can influence coral-associated microbial communities. The present study investigates the effects of the Pacific brown macroalga Lobophora sp. (due to the shifting nature of the Lobophora species complex, it will be referred to here as Lobophora sp.) on coral bacterial isolates, coral larvae, and the microbiome associated with the coral Porites cylindrica. Crude aqueous and organic macroalgal extracts were found to inhibit the growth of coral-associated bacteria. Extracts and fractions were also shown to inhibit coral larval settlement and cause mortality at concentrations lower (pathogenic. Macroalgae (e.g., seaweeds) can physically and chemically interact with corals, causing abrasion, bleaching, and overall stress. This study contributes to a growing body of evidence suggesting that macroalgae play a critical role in shifting the coral holobiont equilibrium, which may promote the invasion of opportunistic pathogens and cause coral mortality, facilitating additional macroalgal growth and invasion in the reef. Thus, macroalgae not only contribute to a decline in coral fitness but also influence coral reef ecosystem structure. © Crown copyright 2016.

  19. Aleloquímico produzido pela gramínea forrageira Brachiaria humidicola Allelochemical produced by the forage grass Brachiaria humidicola

    Directory of Open Access Journals (Sweden)

    A.P.S. Souza Filho

    2005-03-01

    Full Text Available Os métodos usuais de controle de plantas daninhas não atendem mais as atuais e futuras exigências da sociedade em relação à preservação dos recursos naturais e da qualidade de vida. Uma alternativa para essa questão seriam os metabólitos secundários produzidos pelas plantas, que apresentam pouco risco para o ambiente e para os interesses da sociedade. Os objetivos deste trabalho foram isolar, identificar e caracterizar a atividade alelopática de substâncias químicas produzidas pela gramínea forrageira Brachiaria humidicola. Analisaram-se os efeitos alelopáticos dos extratos, frações e substâncias isoladas sobre a germinação e o desenvolvimento da radícula das invasoras malícia, fedegoso e mata-pasto, em bioensaios monitorados em períodos de 10 dias, em condições de 25 ºC e fotoperíodo de 12 horas, para a germinação, e 24 horas, para o desenvolvimento da radícula. A partir do extrato hidrometanólico, foi isolado e identificado o ácido p-cumárico. Os efeitos alelopáticos estiveram positivamente relacionados à concentração do ácido, à espécie de planta daninha e à característica da espécie analisada. Comparativamente, fedegoso e malícia se mostraram mais sensíveis aos efeitos alelopáticos. A germinação e o desenvolvimento da radícula do mata-pasto não foram afetados pelo ácido p-cumárico nas concentrações de 1,0 a 8,0 mg L¹. O alongamento da radícula se mostrou mais sensível aos efeitos alelopáticos do ácido pcumárico do que a germinação das sementes.The traditional methods of weed control in cultivated pasture do not meet society's present and future needs of protecting natural resources and life quality. An alternative to this problem could be the use of secondary metabolites produced by plants. These products present few risks to the environment and meet society interests. Therefore, this research was carried out to isolate, identify and characterize the allelopathic activity of chemical compounds produced by the forage grass Brachiaria humidicola. The allelopathic effects of the extracts, fractions and compound were tested on seed germination and root elongation of the weeds Mimosa pudica, Senna obtusifolia and Senna occidentalis. Germination bioassays were developed under 25 ºC and a photoperiod of 12 hours. For root elongation, the bioassay conditions were 25 ºC and photoperiod of 24 hours. Hydromethanolic extract was used as a source for isolating and identifying p-coumaric acid. The allelopathic effects were positively related to p-coumaric acid concentration, weed species and the evaluated parameter. Comparatively, S. occidentalis and M. pudica showed the greatest sensitivity to the allelopathic effects. For S. obtusifolia no allelopathic effects promoted by p-coumaric acid on seed germination or on root elongation could be detected under the concentration of 1.0 and 8.0 mg L-1. Root elongation was more sensitive to p-coumaric acid allelophatic effects than seed germination.

  20. Slide 24

    Indian Academy of Sciences (India)

    The quantum of oils & allelochemic in the soil decreases with distance from the tree and depth from the soil surface. Different crops differ in the quantum of response to the allelochemics. However, the response is governed by the ratio between the seed coat thickness and seed volume of the target crop. Lesser the value ...

  1. Glucosinolate-Containing Seed Meal as a Soil Amendment to Control Plant Pests: 2000-2002

    Energy Technology Data Exchange (ETDEWEB)

    Brown, J.; Morra, M. J.

    2005-07-01

    Plants may produce compounds that directly or indirectly affect their biological environment. These compounds fall within a broad category of compounds called allelochemicals, and are exclusive of food that influences growth, health, or behavior of other organisms (Whittaker and Feeney 1971). One reason for interest in allelochemicals is their potential for use in alternative pest management systems. Using plant-produced allelochemicals in agricultural and horticultural practices could minimize synthetic pesticide use, reduce the associated potential for environmental contamination, and contribute to a more sustainable agricultural system.

  2. Evaluation of allelopathic effect of Eclipta alba (L.) Hassk on ...

    African Journals Online (AJOL)

    VAIO

    fractions of donor plant on biochemical activities (carbohydrate content, ... allelochemicals from them into the soil. ... was chilled and subjected to acid hydrolysis using pre-chilled, 3 N ..... Adaptations of plants to water and high Temperature.

  3. 59 - 62 lawan paid

    African Journals Online (AJOL)

    DR. AMIN

    development rather than seed germination. Key words: Allelochemicals, Eucalyptus species, Root length, Germination, Arachis hypogea. INTRODUCTION. Plants that ..... Bangladesh Journal of Botany, 33(2): 79-84. Ahmed, R., Uddin, M. B. ...

  4. Download this PDF file

    African Journals Online (AJOL)

    user

    2015-02-11

    : Trichoderma longibrachiatum, Trichoderma asperellum, Bacillus subtilis ... incidence of 64.71% across the HF, 52.08% across the DS, and 41.98% across the SGS. ... substance, an allelochemical or antibiotic, into a medium.

  5. Long-term allelopathic control of phytoplankton by the submerged macrophyte Elodea nuttallii

    NARCIS (Netherlands)

    Vanderstukken, M.; Declerck, S.A.J.; Decaestecker, E.; Muylaert, K.

    2014-01-01

    Keywords: allelochemicals; chemical ecology; competition; nutrient limitation; shallow lakes Summary 1.It is well known that submerged macrophytes can suppress phytoplankton blooms in lakes and thus promote water quality and biodiversity. One of the possible mechanisms through which submerged

  6. [Algal control ability of allelopathically active submerged macrophytes: a review].

    Science.gov (United States)

    Xiao, Xi; Lou, Li-ping; Li, Hua; Chen, Ying-xu

    2009-03-01

    The inhibitory effect of allelochemicals released by submerged macrophytes on phytoplankton is considered as one of the mechanisms that contribute to the stabilization of clear-water status in shallow lakes. This paper reviewed the research progress in the allelopathy of submerged macrophytes on algae from the aspects of the occurrence frequency and coverage of allelopathically active submerged macrophytes in lakes, and the kinds and allelopathical effects of the allelochemicals released from the macrophytes. The previous researches indicated that allelopathically active submerged macrophyte species such as Myriophyllum, Ceratophyllum, and Elodea were efficient to control phytoplankton, especially when their biomass was high enough, and the dominant algae were sensitive species. The allelochemicals such as hydroxybenzene released by the submerged macrophytes could inhibit the growth of algae. Different phytoplankton species exhibited different sensitivity against allelochemicals, e.g., cyanobacteria and diatom were more sensitive than green algae, while epiphytic species were less sensitive than phytoplankton. Environmental factors such as light, temperature, and nutrients could significantly affect the allelopathical effect of submerged macrophytes. The research of the allelopathy of submerged macrophytes is still at its beginning, and further researches are needed on the effects of environmental factors on the allelopathy, extraction and identification of allelochemicals, selective algal control mechanisms, and metabolism of the allelochmicals.

  7. Genetic variation for sensitivity to a thyme monoterpene in associated plant species.

    Science.gov (United States)

    Jensen, Catrine Grønberg; Ehlers, Bodil Kirstine

    2010-04-01

    Recent studies have shown that plant allelochemicals can have profound effects on the performance of associated species, such that plants with a history of co-existence with "chemical neighbour" plants perform better in their presence compared to naïve plants. This has cast new light on the complexity of plant-plant interactions and plant communities and has led to debates on whether plant communities are more co-evolved than traditionally thought. In order to determine whether plants may indeed evolve in response to other plants' allelochemicals it is crucial to determine the presence of genetic variation for performance under the influence of specific allelochemicals and show that natural selection indeed operates on this variation. We studied the effect of the monoterpene carvacrol-a dominant compound in the essential oil of Thymus pulegioides-on three associated plant species originating from sites where thyme is either present or absent. We found the presence of genetic variation in both naïve and experienced populations for performance under the influence of the allelochemical but the response varied among naïve and experienced plant. Plants from experienced populations performed better than naïve plants on carvacrol soil and contained significantly more seed families with an adaptive response to carvacrol than naïve populations. This suggests that the presence of T. pulegioides can act as a selective agent on associated species, by favouring genotypes which perform best in the presence of its allelochemicals. The response to the thyme allelochemical varied from negative to neutral to positive among the species. The different responses within a species suggest that plant-plant interactions can evolve; this has implications for community dynamics and stability.

  8. Allelopathy in pigweed (a review

    Directory of Open Access Journals (Sweden)

    Pedro Luis da Costa Aguiar Alves

    2011-09-01

    Full Text Available Amaranthus spp. are plants with proven allelopathic potential. The release of allelochemicals from Amaranthus spp. in the environment can influence seed germination, photosynthesis rate, reduce growth and, consequently, the productivity of various plant species. Among the species with allelopathic potential are Amaranthus blitoides, Amaranthus gracilis, Amaranthus hybridus, Amaranthus palmeri, Amaranthus retroflexus, Amaranthus spinosus and Amaranthus viridis, with A. retroflexus being the most studied species and A. spinosus being the species with the greatest allelopathic potential. Due to the large quantities of allelochemicals produced by Amaranthus spp. these plants stand out as future suppliers of chemical molecules for bioherbicides and semisynthetic herbicides.

  9. Allelopathic potential of Rapanea umbellata leaf extracts.

    Science.gov (United States)

    Novaes, Paula; Imatomi, Maristela; Varela, Rosa M; Molinillo, José M G; Lacret, Rodney; Gualtieri, Sonia C J; Macías, Francisco A

    2013-08-01

    The stressful conditions associated with the Brazilian savanna (Cerrado) environment were supposed to favor higher levels of allelochemicals in Rapanea umbellata from this ecosystem. The allelopathic potential of R. umbellata leaf extracts was studied using the etiolated wheat coleoptile and standard phytotoxicity bioassays. The most active extract was selected to perform a bioassay-guided isolation, which allowed identifying lutein (1) and (-)-catechin (2) as potential allelochemicals. Finally, the general bioactivity of the two compounds was studied, which indicated that the presence of 1 might be part of the defense mechanisms of this plant. Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.

  10. Inhibition of tomato (Solanum lycopersicum L.) root growth by cyanamide is not always accompanied with enhancement of ROS production.

    Science.gov (United States)

    Soltys, Dorota; Gniazdowska, Agnieszka; Bogatek, Renata

    2013-05-01

    Mode of action of allelochemicals in target plants is currently widely studied. Cyanamide is one of the newly discovered allelochemical, biosynthesized in hairy vetch. Recently, it has been recognized that cyanamide is plant growth inhibitor, which affects mitosis in root tip cells and causes,e.g., disorder in phytohormonal balance. We also demonstrated that CA may act as oxidative stress agent but it strictly depends on plant species, exposure time and doses. Roots of tomato seedling treated with water solution of 1.2 mM cyanamide did not exhibit elevated reactive oxygen species concentration during the whole culture period.

  11. Enzyme activity in bioregulator-treated tomato (Solanum ...

    African Journals Online (AJOL)

    USER

    2010-05-31

    May 31, 2010 ... African Journal of Biotechnology Vol. 9(22), pp. 3264-3271, 31 ... In this work, spectrophotometric analysis ... most stable enzymes in vegetables and its thermal destruc-tion ... proteins, carbohydrates, lipids and allelochemicals (Hedin et al., 1995) ..... activities isolated from corn root plasma membrane. Plant.

  12. Collection and identification of algal species

    African Journals Online (AJOL)

    Mohabi

    2012-04-24

    Apr 24, 2012 ... each type was dissolved in 10 ml distilled water and then added in the form of 100 IU crystalline penicillin and 100 µg ..... nitrogen and total reducing sugars that might be implicated as allelochemical agents. Extra ..... Simple methods of estimating fifty percent end points. Am. J. Hyg. 27: 493-497. Saffan SE ...

  13. Effects of benzoic acid and cadmium toxicity on wheat seedlings

    Directory of Open Access Journals (Sweden)

    Kavita Yadav

    2013-06-01

    Full Text Available Benzoic acid (BA and Cd exhibit cumulative effects on plants due to their accumulation in the soil. The present study reports the effects of BA an allelochemical, Cd and their combinations on seed germination, seedling growth, biochemical parameters, and response of antioxidant enzymes in Triticum aestivum L. The experiment was conducted in sand supplemented with Hoagland nutrient solution. Benzoic acid was applied at concentrations of 0.5, 1.0, and 1.5 mM with or without Cd (7 mg L-1 to observe effects of allelochemical and Cd alone and in combination on wheat. Both stresses exhibited inhibitory effect on growth and metabolism of wheat seedlings. The allelochemical in single and combined treatments with Cd decreased seedling growth as compared to Cd stress. The two stresses significantly enhanced malondialdehyde content of wheat seedlings. The activity of other antioxidant enzymes, viz. superoxide dismutase (SOD, catalase (CAT, ascorbate peroxidase (APX, and guaiacol peroxidase (POX were also recorded. SOD increased in seedlings under the two stresses. CAT more prominently ameliorates the toxic effects of H2O2 as compared with APX and POX and protected wheat seedlings from oxidative stress. Allelochemical buttressed the toxic effect of Cd on wheat seedlings.

  14. Are population differences in plant quality reflected in the preference and performance of two endoparasitoid wasps?

    NARCIS (Netherlands)

    Gols, R.; Dam, van N.M.; Raaijmakers, C.E.; Dicke, M.; Harvey, J.A.

    2009-01-01

    In recent years, increasing attention has been paid in exploring the role of direct plant defence, through the production of allelochemicals, on the performance of parasitoid wasps and their hosts. However, few studies have determined if parasitoids can detect differences in plant quality and thus

  15. Assessment of allelopathic potential of Cassia sophera L. on ...

    African Journals Online (AJOL)

    ufuoma

    2014-02-26

    Feb 26, 2014 ... weed including leaf, stem, root, and fruit depending upon plant species have ... room temperature (20±2ºC) for 24 h with occasional shaking. The mixture was filtered ..... toxic mechanisms induced by allelochemicals is the inhibition of ... Arnon DI (1949). Copper enzymes in isolated chloroplasts polyphenol.

  16. Quantification of alkaloids, phenols and flavonoids in sunflower ...

    African Journals Online (AJOL)

    Allelochemicals in leaves, stems and roots of sunflower (cv Hysun 38) were determined using thin layer chromatography (TLC) for alkaloids and spectrophotometry for phenols and flavonoids. In the TLC, the highest Rf value was recorded in leaves, followed by roots and stems, a sequence that held true also for the quantity ...

  17. Antioxidant enzymes in Spodoptera littoralis (Boisduval): Are they enhanced to protect gut tissues during oxidative stress?

    Czech Academy of Sciences Publication Activity Database

    Krishnan, Natraj; Kodrík, Dalibor

    2006-01-01

    Roč. 52, č. 1 (2006), s. 11-20 ISSN 0022-1910 R&D Projects: GA ČR(CZ) GA522/05/0151 Institutional research plan: CEZ:AV0Z50070508 Keywords : antioxidant enzyme * oxidative stress * allelochemicals Subject RIV: CE - Biochemistry Impact factor: 2.019, year: 2006

  18. Weeds Cause Losses in Field Crops through Allelopathy

    Directory of Open Access Journals (Sweden)

    Ali ZOHAIB

    2016-03-01

    Full Text Available A large number of weeds are known to be associated with crops and causing economic losses. Weeds interfere with crops through competition and allelopathy. They produce secondary metabolites known as allelochemicals, which belong to numerous chemical classes such as phenolics, alkaloids, fatty acids, indoles, terpens etc. However, phenolics are the predominant class of allelochemicals. The allelochemicals release from weed plants takes place through leaf leachates, decomposition of plant residues, volatilization and root exudates. Weeds leave huge quantities of their residues in field and affect the associated, as well as succeeding crops, in various cropping systems. Liberation of allelochemicals from weeds affects the germination, stand establishment, growth, yield and physiology of crop plants. They cause substantial reduction in germination and growth of the crop plants by altering various physiological processes such as enzyme activity, protein synthesis, photosynthesis, respiration, cell division and enlargement, which ultimately leads to a significant reduction in crop yield. In crux, allelopathic weeds represent a potential threat for crop plants and cause economic losses.

  19. Allelopathic effect of aqueous extract of fresh leaf castor beans ...

    African Journals Online (AJOL)

    Allelopathy defines the production of specific biomolecules (allelochemical) by a plant that can induce positive or negative impacts on another culture. The crop of castor beans (Ricinus communis L.) is being economically valued and receiving attention, mainly by the biodiesel production, castor oil and animal feeding.

  20. The allelopathic effects of three crop residues on the germination ...

    African Journals Online (AJOL)

    ... maize inflorescences showed significant differences when compared to the control. No growth was recorded in the radicle until 96 hrs of the experiment in all the extract – treated seeds from the three crop residues while the control germinated at 72 hours. Keywords: Allelopathy, allelochemical, biomolecules, Sphenostylis ...

  1. Antifungal activity of rice straw extract on some phytopathogenic fungi

    African Journals Online (AJOL)

    The antifungal activity of allelochemicals extracted from rice straw on the radial growth rate and the activity of some hydrolyzing enzymes of Aspergillus flavus, Alternaria alternata and Botrytis cinerea were studied in vitro. Five different concentrations (2, 4, 6, 8 and 10%, w/v) of water, methanol and acetone extracts of rice ...

  2. Allelopathy in pigweed (a review)

    OpenAIRE

    Pedro Luis da Costa Aguiar Alves; Leonardo Bianco de Carvalho; Marcelo Claro de Souza; Paulo Roberto Fidelis Giancotti

    2011-01-01

    Amaranthus spp. are plants with proven allelopathic potential. The release of allelochemicals from Amaranthus spp. in the environment can influence seed germination, photosynthesis rate, reduce growth and, consequently, the productivity of various plant species. Among the species with allelopathic potential are Amaranthus blitoides, Amaranthus gracilis, Amaranthus hybridus, Amaranthus palmeri, Amaranthus retroflexus, Amaranthus spinosus and Amaranthus viridis, with A. retroflexus being the mo...

  3. Effects of dietary nicotine on the development of an insect herbivore, its parasitoid and secondary hyperparasitoid over four trophic levels

    NARCIS (Netherlands)

    Harvey, J.A.; Dam, van N.M.; Witjes, L.M.A.; Soler, R.; Gols, R.

    2007-01-01

    1. Allelochemicals in herbivore diet are known to affect the development of higher trophic levels, such as parasitoids and predators. 2. This study examines how differing levels of nicotine affects the development of a herbivore, its parasitoid and secondary hyperparasitoid over four trophic levels.

  4. Impact of crop residues on seed germination of native desert plants ...

    African Journals Online (AJOL)

    Crop residues produce allelochemicals that may inhibit seed germination of many weeds. In this study, I assessed the effect of aqueous extracts of three crop residues (radish, rocket and rhodes) on final germination percentage and germination rate of four desert plants recorded as weeds in the United Arab Emirates farms ...

  5. Mechanical wounding under field conditions: A potential tool to increase the allelopathic inhibitory effect of cover crops on weeds?

    NARCIS (Netherlands)

    Kruidhof, H.M.; Dam, van N.M.; Ritz, C.; Lotz, L.A.P.; Kropff, M.J.; Bastiaans, L.

    2014-01-01

    To increase the inhibitory effect of soil-incorporated cover crop residues on germination and early growth of weeds, the allelochemical content of the cover crop at the time of soil incorporation should be maximal. We investigated whether mechanical damaging in spring induced the production of

  6. Allelopathic effect of aqueous extract of fresh leaf castor beans ...

    African Journals Online (AJOL)

    Rukevwe S. Abraka

    2016-12-07

    Dec 7, 2016 ... In this study, the allelopathic effect of aqueous extract from fresh leaves of castor .... triturated with electric blender and sieved for the extract preparation. .... (A), Leaf fresh mass; (B), root fresh mass; (C), stem diameter; (D), aerial part length. .... Naphthoquinones as allelochemical triggers of programmed cell.

  7. Experience-based behavioral and chemosensory changes in the generalist insect herbivore Helicoverpa armigera exposed to two deterrent plant chemicals

    NARCIS (Netherlands)

    Zhou, D.; Loon, van J.J.A.; Wang, C.Z.

    2010-01-01

    Behavioral and electrophysiological responses of larvae of the polyphagous moth species Helicoverpa armigera to two plant-derived allelochemicals were studied, both in larvae that had been reared on a diet devoid of these compounds and in larvae previously exposed to these compounds. In dual-choice

  8. Phytotoxic studies of medicinal plant species of Pakistan

    International Nuclear Information System (INIS)

    Gilani, S.A.; Adnan, M.; Kikuchi, A.; Fujii, Y.; Shinwari, Z.K.; Kazuo, N.; Watanabe, K.N.

    2010-01-01

    Allelopathic screening of 81 medicinal plant species, collected from North West Frontier Province (NWFP) Pakistan, was carried out to identify significantly higher allelopathic species for future phyto chemical analyses. For this purpose, sandwich method was used to test allelopathic potentials of leaf leachates of these plant species against lettuce seeds (Lactuca sativa L.). Two different concentrations of 10 mg and 50 mg of leaf leachates were used in the study. The radicle and hypocotyl growths were measured and compared with control treatments. It was observed that an endemic species Seriphidium kurramense, Andrachne cordifolia and Rhazya stricta were the stronger phyto toxic plants as compared to the other test species. Based on the current screening, three potential medicinal plants are recommended for future bioassay guided isolation of allelochemicals and for genetic diversity studies. It would also be interesting to see correlation between genetic markers and isolated allelochemicals. (author)

  9. Analysis of correlation structure in Lymantria dispar L. larvae from locally adapted populations

    Directory of Open Access Journals (Sweden)

    Mrdaković Marija

    2013-01-01

    Full Text Available The influence of allelochemical stress and population origin on the patterns of phenotypic and genetic correlations among life history traits and digestive enzyme activities were investigated in larvae of the gypsy moth (Lymantria dispar L.; Lepidoptera: Lymantriidae. Thirty-two full-sib families from oak (suitable host plant, Quercus population, and twenty-six full-sib families from locust-tree (unsuitable host plant, Robinia population forests were reared on an artificial diet, with or without a 5% tannic acid supplement. Comparison of correlation matrices revealed significant similarity between the two populations in the structure of phenotypic and genetic correlations of life history traits and of digestive enzyme activities. The patterns of correlations of the examined traits, within each of the two locally adapted populations and in the presence of allelochemical stress, remained stabile despite the different selection pressures that mold these traits. [Projekat Ministarstva nauke Republike Srbije, br. 173027

  10. Study of Allelopathic Interaction of Wheat (Triticum aestivum L. and Some Weed Species Using Equal - Compartment – Agar Method

    Directory of Open Access Journals (Sweden)

    M. R Labbafi

    2012-02-01

    Full Text Available There are many methods for weed management one of them is putting allelopathic and cover crop in weed management programs. In order to study the effect of sowing time (delayed sowing, synchronic sowing and wheat cultivars (Shiraz, Roshan, Tabasi, Niknejad on allelopathic interaction of wheat and weed species (Secale cereale L., Avena ludoviciana L.: monocotyledon, Convolvulus arvensis L. and Vicia villosa L.: dicotyledon, an experiment was conducted with factorial arrangement in a completely randomized design and 4 replications. According to the results, the inhibitory effect of wheat on monocot weeds (oat and rye was more than in synchronic sowing and the inhibitory effect of wheat on dicot weeds (bindweed and vetch was more than in delayed sowing. Effect of wheat cultivars on rye and oat (except hypocotyls length was inhibitory and that of vetch was stimulatory. Hypocotyls length showed the most sensitivity to released allelochemicals from wheat cultivars, because root has the most contact with allelochemicals in the soil.

  11. Allelopathy in agroecosystems: Wheat phytotoxicity and its possible roles in crop rotation.

    Science.gov (United States)

    Lodhi, M A; Bilal, R; Malik, K A

    1987-08-01

    The germination rates of cotton and wheat seeds were significantly affected by various extracts of wheat mulch and soils collected from the wheat field. This toxicity was even more pronounced against seedling growth. Five allelochemics: ferulic,p-coumaric,p-OH benzoic, syringic, and vanillic acids, were identified from the wheat mulch and its associated soil. Quantitatively, ferulic acid was found at higher concentrations thanp-coumaric acid in the soil. Various concentrations of ferulic andp-coumaric acids were toxic to the growth of radish in a bioassay. The functional aspects of allelochemic transfer from decaying residue to soil and the subsequent microbial degradation within agroecosystems are discussed, particularly as they relate to wheat crop rotation, with wheat and cotton, in Pakistan.

  12. The globally distributed genus Alexandrium: multifaceted roles in marine ecosystems and impacts on human health

    OpenAIRE

    Anderson, Donald M.; Alpermann, Tilman J.; Cembella, Allan D.; Collos, Yves; Masseret, Estelle; Montresor, Marina

    2012-01-01

    The dinoflagellate genus Alexandrium is one of the major harmful algal bloom (HAB) genera with respect to the diversity, magnitude and consequences of blooms. The ability of Alexandrium to colonize multiple habitats and to persist over large regions through time is testimony to the adaptability and resilience of this group of species. Three different families of toxins, as well as an as yet incompletely characterized suite of allelochemicals are produced among Alexandrium species. Nutri...

  13. A stable-isotope mass spectrometry-based metabolic footprinting approach to analyze exudates from phytoplankton

    DEFF Research Database (Denmark)

    Weber, Ralf J. M.; Selander, Erik; Sommer, Ulf

    2013-01-01

    Phytoplankton exudates play an important role in pelagic ecology and biogeochemical cycles of elements. Exuded compounds fuel the microbial food web and often encompass bioactive secondary metabolites like sex pheromones, allelochemicals, antibiotics, or feeding attractants that mediate biological...... interactions. Despite this importance, little is known about the bioactive compounds present in phytoplankton exudates. We report a stable-isotope metabolic footprinting method to characterise exudates from aquatic autotrophs. Exudates from 13C-enriched alga were concentrated by solid phase extraction...

  14. Chemical ecology of insect-plant interactions: ecological significance of plant secondary metabolites.

    OpenAIRE

    Nishida, Ritsuo

    2014-01-01

    Plants produce a diverse array of secondary metabolites as chemical barriers against herbivores. Many phytophagous insects are highly adapted to these allelochemicals and use such unique substances as the specific host-finding cues, defensive substances of their own, and even as sex pheromones or their precursors by selectively sensing, incorporating, and/or processing these phytochemicals. Insects also serve as pollinators often effectively guided by specific floral fragrances. This review d...

  15. Methods of collection of plant root exudates in relation to plant metabolism and purpose: A review

    Czech Academy of Sciences Publication Activity Database

    Vránová, V.; Rejšek, K.; Skene, K. R.; Janouš, Dalibor; Formanek, P.

    2013-01-01

    Roč. 176, č. 2 (2013), s. 175-199 ISSN 1436-8730 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA MŠk(CZ) LM2010007 Institutional support: RVO:67179843 Keywords : allelochemical / CAM / C3 * C4 metabolism * retrieval * rhizodeposition * rhizosphere Subject RIV: EH - Ecology, Behaviour Impact factor: 1.663, year: 2013

  16. Chemical Characterization and Release Efficiency of Defatted Mustard Meals: 2000-2002

    Energy Technology Data Exchange (ETDEWEB)

    Morra, M. J.

    2005-07-01

    Glucosinolates, compounds that occur in agronomically important crops, may represent a viable source of allelochemic control for various soil-borne plant pests. Toxicity is not attributed to intact glucosinolates, but instead to biologically active products such as isothiocyanates (ITCs), organic cyanides, oxazolidinethiones, and ionic thiocyanate (SCN-) released upon enzymatic degradation by myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1) in the presence of water.

  17. Phytotoxic effects of (+/--catechin in vitro, in soil, and in the field.

    Directory of Open Access Journals (Sweden)

    Inderjit

    Full Text Available BACKGROUND: Exploring the residence time of allelochemicals released by plants into different soils, episodic exposure of plants to allelochemicals, and the effects of allelochemicals in the field has the potential to improve our understanding of interactions among plants. METHODOLOGY/PRINCIPAL FINDINGS: We conducted experiments in India and the USA to understand the dynamics of soil concentrations and phytotoxicity of (+/--catechin, an allelopathic compound exuded from the roots of Centaurea maculosa, to other plants in vitro and in soil. Experiments with single and pulsed applications into soil were conducted in the field. Experimental application of (+/--catechin to soils always resulted in concentrations that were far lower than the amounts added but within the range of reported natural soil concentrations. Pulses replenished (+/--catechin levels in soils, but consistently at concentrations much lower than were applied, and even pulsed concentrations declined rapidly. Different natural soils varied substantially in the retention of (+/--catechin after application but consistent rapid decreases in concentrations over time suggested that applied experimental concentrations may overestimate concentrations necessary for phytotoxicity by over an order of magnitude. (+/--Catechin was not phytotoxic to Bambusa arundinacea in natural Indian soil in a single pulse, but soil concentrations at the time of planting seeds were either undetectable or very low. However, a single dose of (+/--catechin suppressed the growth of bamboo in sand, in soil mixed with organic matter, and Koeleria macrantha in soils from Montana and Romania, and in field applications at 40 microg l(-1. Multiple pulses of (+/--catechin were inhibitory at very low concentrations in Indian soil. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that (+/--catechin is highly dynamic in natural soils, but is phytotoxic well below natural concentrations measured in some soils and applied

  18. Phytotoxic Effects of (±)-Catechin In vitro, in Soil, and in the Field

    Science.gov (United States)

    Inderjit; Pollock, Jarrod L.; Callaway, Ragan M.; Holben, William

    2008-01-01

    Background Exploring the residence time of allelochemicals released by plants into different soils, episodic exposure of plants to allelochemicals, and the effects of allelochemicals in the field has the potential to improve our understanding of interactions among plants. Methodology/Principal Findings We conducted experiments in India and the USA to understand the dynamics of soil concentrations and phytotoxicity of (±)-catechin, an allelopathic compound exuded from the roots of Centaurea maculosa, to other plants in vitro and in soil. Experiments with single and pulsed applications into soil were conducted in the field. Experimental application of (±)-catechin to soils always resulted in concentrations that were far lower than the amounts added but within the range of reported natural soil concentrations. Pulses replenished (±)-catechin levels in soils, but consistently at concentrations much lower than were applied, and even pulsed concentrations declined rapidly. Different natural soils varied substantially in the retention of (±)-catechin after application but consistent rapid decreases in concentrations over time suggested that applied experimental concentrations may overestimate concentrations necessary for phytotoxicity by over an order of magnitude. (±)-Catechin was not phytotoxic to Bambusa arundinacea in natural Indian soil in a single pulse, but soil concentrations at the time of planting seeds were either undetectable or very low. However, a single dose of (±)-catechin suppressed the growth of bamboo in sand, in soil mixed with organic matter, and Koeleria macrantha in soils from Montana and Romania, and in field applications at 40 µg l−1. Multiple pulses of (±)-catechin were inhibitory at very low concentrations in Indian soil. Conclusions/Significance Our results demonstrate that (±)-catechin is highly dynamic in natural soils, but is phytotoxic well below natural concentrations measured in some soils and applied at low concentrations in

  19. Enhanced lignin monomer production caused by cinnamic Acid and its hydroxylated derivatives inhibits soybean root growth.

    Directory of Open Access Journals (Sweden)

    Rogério Barbosa Lima

    Full Text Available Cinnamic acid and its hydroxylated derivatives (p-coumaric, caffeic, ferulic and sinapic acids are known allelochemicals that affect the seed germination and root growth of many plant species. Recent studies have indicated that the reduction of root growth by these allelochemicals is associated with premature cell wall lignification. We hypothesized that an influx of these compounds into the phenylpropanoid pathway increases the lignin monomer content and reduces the root growth. To confirm this hypothesis, we evaluated the effects of cinnamic, p-coumaric, caffeic, ferulic and sinapic acids on soybean root growth, lignin and the composition of p-hydroxyphenyl (H, guaiacyl (G and syringyl (S monomers. To this end, three-day-old seedlings were cultivated in nutrient solution with or without allelochemical (or selective enzymatic inhibitors of the phenylpropanoid pathway in a growth chamber for 24 h. In general, the results showed that 1 cinnamic, p-coumaric, caffeic and ferulic acids reduced root growth and increased lignin content; 2 cinnamic and p-coumaric acids increased p-hydroxyphenyl (H monomer content, whereas p-coumaric, caffeic and ferulic acids increased guaiacyl (G content, and sinapic acid increased sinapyl (S content; 3 when applied in conjunction with piperonylic acid (PIP, an inhibitor of the cinnamate 4-hydroxylase, C4H, cinnamic acid reduced H, G and S contents; and 4 when applied in conjunction with 3,4-(methylenedioxycinnamic acid (MDCA, an inhibitor of the 4-coumarate:CoA ligase, 4CL, p-coumaric acid reduced H, G and S contents, whereas caffeic, ferulic and sinapic acids reduced G and S contents. These results confirm our hypothesis that exogenously applied allelochemicals are channeled into the phenylpropanoid pathway causing excessive production of lignin and its main monomers. By consequence, an enhanced stiffening of the cell wall restricts soybean root growth.

  20. Research Progress on the use of Plant Allelopathy in Agriculture and the Physiological and Ecological Mechanisms of Allelopathy.

    Science.gov (United States)

    Cheng, Fang; Cheng, Zhihui

    2015-01-01

    Allelopathy is a common biological phenomenon by which one organism produces biochemicals that influence the growth, survival, development, and reproduction of other organisms. These biochemicals are known as allelochemicals and have beneficial or detrimental effects on target organisms. Plant allelopathy is one of the modes of interaction between receptor and donor plants and may exert either positive effects (e.g., for agricultural management, such as weed control, crop protection, or crop re-establishment) or negative effects (e.g., autotoxicity, soil sickness, or biological invasion). To ensure sustainable agricultural development, it is important to exploit cultivation systems that take advantage of the stimulatory/inhibitory influence of allelopathic plants to regulate plant growth and development and to avoid allelopathic autotoxicity. Allelochemicals can potentially be used as growth regulators, herbicides, insecticides, and antimicrobial crop protection products. Here, we reviewed the plant allelopathy management practices applied in agriculture and the underlying allelopathic mechanisms described in the literature. The major points addressed are as follows: (1) Description of management practices related to allelopathy and allelochemicals in agriculture. (2) Discussion of the progress regarding the mode of action of allelochemicals and the physiological mechanisms of allelopathy, consisting of the influence on cell micro- and ultra-structure, cell division and elongation, membrane permeability, oxidative and antioxidant systems, growth regulation systems, respiration, enzyme synthesis and metabolism, photosynthesis, mineral ion uptake, protein and nucleic acid synthesis. (3) Evaluation of the effect of ecological mechanisms exerted by allelopathy on microorganisms and the ecological environment. (4) Discussion of existing problems and proposal for future research directions in this field to provide a useful reference for future studies on plant

  1. The impact of microbial biotransformation of catechin in enhancing the allelopathic effects of Rhododendron formosanum.

    Science.gov (United States)

    Wang, Chao-Min; Li, Tsai-Chi; Jhan, Yun-Lian; Weng, Jen-Hsien; Chou, Chang-Hung

    2013-01-01

    Rhododendron formosanum is distributed widely in the central mountains in Taiwan and the major allelopathic compound in the leaves has been identified as (-)-catechin, which is also a major allelochemical of an invasive spotted knapweed in North America. Soil microorganisms play key roles in ecosystems and influence various important processes, including allelopathy. However, no microorganism has been identified as an allelochemical mediator. This study focused on the role of microorganisms in the allelopathic effects of R. formosanum. The microorganism population in the rhizosphere of R. formosanum was investigated and genetic analysis revealed that the predominant genera of microorganisms in the rhizosphere of R. formosanum were Pseudomonas, Herbaspirillum, and Burkholderia. The dominant genera Pseudomonas utilized (-)-catechin as the carbon source and catalyzed the conversion of (-)-catechin into protocatechuic acid in vitro. The concentrations of allelochemicals in the soil were quantified by liquid chromatography-electrospray ionization/tandem mass spectrometry. The concentration of (-)-catechin in the soil increased significantly during the extreme rainfall in the summer season and suppressed total bacterial populations. Protocatechuic acid accumulation was observed while total bacterial populations increased abundantly in both laboratory and field studies. Allelopathic interactions were tested by evaluating the effects of different allelochemicals on the seed germination, radicle growth, and photosynthesis system II of lettuce. Protocatechuic acid exhibited higher phytotoxicity than (-)-catechin did and the effect of (-)-catechin on the inhibition of seed germination was enhanced by combining it with protocatechuic acid at a low concentration. This study revealed the significance of the allelopathic interactions between R. formosanum and microorganisms in the rhizosphere. These findings demonstrate that knowledge regarding the precise biotransformation

  2. The impact of microbial biotransformation of catechin in enhancing the allelopathic effects of Rhododendron formosanum.

    Directory of Open Access Journals (Sweden)

    Chao-Min Wang

    Full Text Available Rhododendron formosanum is distributed widely in the central mountains in Taiwan and the major allelopathic compound in the leaves has been identified as (--catechin, which is also a major allelochemical of an invasive spotted knapweed in North America. Soil microorganisms play key roles in ecosystems and influence various important processes, including allelopathy. However, no microorganism has been identified as an allelochemical mediator. This study focused on the role of microorganisms in the allelopathic effects of R. formosanum. The microorganism population in the rhizosphere of R. formosanum was investigated and genetic analysis revealed that the predominant genera of microorganisms in the rhizosphere of R. formosanum were Pseudomonas, Herbaspirillum, and Burkholderia. The dominant genera Pseudomonas utilized (--catechin as the carbon source and catalyzed the conversion of (--catechin into protocatechuic acid in vitro. The concentrations of allelochemicals in the soil were quantified by liquid chromatography-electrospray ionization/tandem mass spectrometry. The concentration of (--catechin in the soil increased significantly during the extreme rainfall in the summer season and suppressed total bacterial populations. Protocatechuic acid accumulation was observed while total bacterial populations increased abundantly in both laboratory and field studies. Allelopathic interactions were tested by evaluating the effects of different allelochemicals on the seed germination, radicle growth, and photosynthesis system II of lettuce. Protocatechuic acid exhibited higher phytotoxicity than (--catechin did and the effect of (--catechin on the inhibition of seed germination was enhanced by combining it with protocatechuic acid at a low concentration. This study revealed the significance of the allelopathic interactions between R. formosanum and microorganisms in the rhizosphere. These findings demonstrate that knowledge regarding the precise

  3. Dose-Response—A Challenge for Allelopathy?

    OpenAIRE

    Belz, Regina G.; Hurle, Karl; Duke, Stephen O.

    2005-01-01

    The response of an organism to a chemical depends, among other things, on the dose. Nonlinear dose-response relationships occur across a broad range of research fields, and are a well established tool to describe the basic mechanisms of phytotoxicity. The responses of plants to allelochemicals as biosynthesized phytotoxins, relate as well to nonlinearity and, thus, allelopathic effects can be adequately quantified by nonlinear mathematical modeling. The current paper applies the concept of no...

  4. Allelopathy and resource competition: the effects of Phragmites australis invasion in plant communities

    OpenAIRE

    Uddin, Md Nazim; Robinson, Randall William

    2017-01-01

    Background Phragmites australis, a ubiquitous wetland plant, has been considered one of the most invasive species in the world. Allelopathy appears to be one of the invasion mechanisms, however, the effects could be masked by resource competition among target plants. The difficulty of distinguishing allelopathy from resource competition among plants has hindered investigations of the role of phytotoxic allelochemicals in plant communities. This has been addressed via experiments conducted in ...

  5. Allelopathy of Teucrium Royleanum Wall. Ex Benth. from Pakistan

    OpenAIRE

    Ahmad, Shabir; Arfan, Mohammad; Khan, Abdul Latif; Ullah, Riaz; Hussain, Javid; Muhammad, Zia; Khan, Rasool; Khan, Naeem; Watanabe, Kazuo N.

    2011-01-01

    Teucrium royleanum was tested by four variant assays using lettuce seeds, showing excellent inhibition. The plants leaf leachates were assayed by Sandwich and Homogenated Sandwich Methods while Dish Pack Method was used for the evaluation of essential oils. The above stated methods confirm the presence of allelochemicals in T. royleanum and were further evaluated in bioassay guided way by total activity approach. The methanol subsequent fractions; hexane, chloroform, ethylacetate, butanol and...

  6. Research progress on the use of plant allelopathy in agriculture and the physiological and ecological mechanisms of allelopathy

    Directory of Open Access Journals (Sweden)

    Fang eCheng

    2015-11-01

    Full Text Available Allelopathy is a common biological phenomenon by which one organism produces biochemicals that influence the growth, survival, development, and reproduction of other organisms. These biochemicals are known as allelochemicals and have beneficial or detrimental effects on target organisms. Plant allelopathy is one of the modes of interaction between receptor and donor plants and may exert either positive effects (e.g., for agricultural management, such as weed control, crop protection, or crop re-establishment or negative effects (e.g., autotoxicity, soil sickness, or biological invasion. To ensure sustainable agricultural development, it is important to exploit cultivation systems that take advantage of the stimulatory / inhibitory influence of allelopathic plants to regulate plant growth and development and to avoid allelopathic autotoxicity. Allelochemicals can potentially be used as growth regulators, herbicides, insecticides and antimicrobial crop protection products. Here, we reviewed the plant allelopathy management practices applied in agriculture and the underlying allelopathic mechanisms described in the literature. The major points addressed are as follows: (1 Description of management practices related to allelopathy and allelochemicals in agriculture. (2 Discussion of the progress regarding the mode of action of allelochemicals and the physiological mechanisms of allelopathy, consisting of the influence on cell micro- and ultra-structure, cell division and elongation, membrane permeability, oxidative and antioxidant systems, growth regulation systems, respiration, enzyme synthesis and metabolism, photosynthesis, mineral ion uptake, protein and nucleic acid synthesis. (3 Evaluation of the effect of ecological mechanisms exerted by allelopathy on microorganisms and the ecological environment. (4 Discussion of existing problems and proposal for future research directions in this field to provide a useful reference for future studies on

  7. Effects of three macroalgae, Ulva linza (Chlorophyta), Corallina pilulifera (Rhodophyta) and Sargassum thunbergii (Phaeophyta) on the growth of the red tide microalga Prorocentrum donghaiense under laboratory conditions

    Science.gov (United States)

    Wang, Renjun; Xiao, Hui; Wang, You; Zhou, Wenli; Tang, Xuexi

    2007-10-01

    Allelopathic effects of several concentrations of fresh tissue and dry powder of three macroalgae, Ulva linza, Corallina pilulifera and Sargassum thunbergii, on the red tide microalga Prorocentrum donghaiense were evaluated in microcosms. Preliminary studies on the algicidal effects of one aqueous and four organic solvent extracts from the macroalgae on the microalga were carried out to confirm the existence of allelochemicals in the tissues of the macroalgae. The effects of macroalgal culture medium filtrate on P. donghaiense were investigated using initial or semi-continuous filtrate addition. Furthermore, the potential effects of the microalga on these three macroalgae were also tested. The results of the microcosm assay showed that the growth of P. donghaiense was strongly inhibited by using fresh tissues and dry powder of the three macroalgae. Both aqueous and methanol extracts of the macroalgae had strong growth inhibitory effects on P. donghaiense, while the other three organic solvent extracts (acetone, ether and chloroform) had no apparent effect on its growth; this suggested that the allelochemicals from these three macroalga had relatively high polarities. The three macroalgal culture medium filtrates exhibited apparent growth inhibitory effect on the microalgae under initial or semi-continuous addition, which suggested that the cells of P. donghaiense are sensitive to the allelochemicals. In contrast, P. donghaiense had no apparent effect on the growth of the macroalgae in coexistence experiment.

  8. Gut microbes may facilitate insect herbivory of chemically defended plants.

    Science.gov (United States)

    Hammer, Tobin J; Bowers, M Deane

    2015-09-01

    The majority of insect species consume plants, many of which produce chemical toxins that defend their tissues from attack. How then are herbivorous insects able to develop on a potentially poisonous diet? While numerous studies have focused on the biochemical counter-adaptations to plant toxins rooted in the insect genome, a separate body of research has recently emphasized the role of microbial symbionts, particularly those inhabiting the gut, in plant-insect interactions. Here we outline the "gut microbial facilitation hypothesis," which proposes that variation among herbivores in their ability to consume chemically defended plants can be due, in part, to variation in their associated microbial communities. More specifically, different microbes may be differentially able to detoxify compounds toxic to the insect, or be differentially resistant to the potential antimicrobial effects of some compounds. Studies directly addressing this hypothesis are relatively few, but microbe-plant allelochemical interactions have been frequently documented from non-insect systems-such as soil and the human gut-and thus illustrate their potential importance for insect herbivory. We discuss the implications of this hypothesis for insect diversification and coevolution with plants; for example, evolutionary transitions to host plant groups with novel allelochemicals could be initiated by heritable changes to the insect microbiome. Furthermore, the ecological implications extend beyond the plant and insect herbivore to higher trophic levels. Although the hidden nature of microbes and plant allelochemicals make their interactions difficult to detect, recent molecular and experimental techniques should enable research on this neglected, but likely important, aspect of insect-plant biology.

  9. Dose-Response—A Challenge for Allelopathy?

    Science.gov (United States)

    Belz, Regina G.; Hurle, Karl; Duke, Stephen O.

    2005-01-01

    The response of an organism to a chemical depends, among other things, on the dose. Nonlinear dose-response relationships occur across a broad range of research fields, and are a well established tool to describe the basic mechanisms of phytotoxicity. The responses of plants to allelochemicals as biosynthesized phytotoxins, relate as well to nonlinearity and, thus, allelopathic effects can be adequately quantified by nonlinear mathematical modeling. The current paper applies the concept of nonlinearity to assorted aspects of allelopathy within several bioassays and reveals their analysis by nonlinear regression models. Procedures for a valid comparison of effective doses between different allelopathic interactions are presented for both, inhibitory and stimulatory effects. The dose-response applications measure and compare the responses produced by pure allelochemicals [scopoletin (7-hydroxy-6-methoxy-2H-1-benzopyran-2-one); DIBOA (2,4-dihydroxy-2H-1,4-benzoxaxin-3(4H)-one); BOA (benzoxazolin-2(3H)-one); MBOA (6-methoxy-benzoxazolin-2(3H)-one)], involved in allelopathy of grain crops, to demonstrate how some general principles of dose responses also relate to allelopathy. Hereupon, dose-response applications with living donor plants demonstrate the validity of these principles for density-dependent phytotoxicity of allelochemicals produced and released by living plants (Avena sativa L., Secale cereale L., Triticum L. spp.), and reveal the use of such experiments for initial considerations about basic principles of allelopathy. Results confirm that nonlinearity applies to allelopathy, and the study of allelopathic effects in dose-response experiments allows for new and challenging insights into allelopathic interactions. PMID:19330161

  10. Dose-response-a challenge for allelopathy?

    Science.gov (United States)

    Belz, Regina G; Hurle, Karl; Duke, Stephen O

    2005-04-01

    The response of an organism to a chemical depends, among other things, on the dose. Nonlinear dose-response relationships occur across a broad range of research fields, and are a well established tool to describe the basic mechanisms of phytotoxicity. The responses of plants to allelochemicals as biosynthesized phytotoxins, relate as well to nonlinearity and, thus, allelopathic effects can be adequately quantified by nonlinear mathematical modeling. The current paper applies the concept of nonlinearity to assorted aspects of allelopathy within several bioassays and reveals their analysis by nonlinear regression models. Procedures for a valid comparison of effective doses between different allelopathic interactions are presented for both, inhibitory and stimulatory effects. The dose-response applications measure and compare the responses produced by pure allelochemicals [scopoletin (7-hydroxy-6-methoxy-2H-1-benzopyran-2-one); DIBOA (2,4-dihydroxy-2H-1,4-benzoxaxin-3(4H)-one); BOA (benzoxazolin-2(3H)-one); MBOA (6-methoxy-benzoxazolin-2(3H)-one)], involved in allelopathy of grain crops, to demonstrate how some general principles of dose responses also relate to allelopathy. Hereupon, dose-response applications with living donor plants demonstrate the validity of these principles for density-dependent phytotoxicity of allelochemicals produced and released by living plants (Avena sativa L., Secale cereale L., Triticum L. spp.), and reveal the use of such experiments for initial considerations about basic principles of allelopathy. Results confirm that nonlinearity applies to allelopathy, and the study of allelopathic effects in dose-response experiments allows for new and challenging insights into allelopathic interactions.

  11. Sorghum allelopathy--from ecosystem to molecule.

    Science.gov (United States)

    Weston, Leslie A; Alsaadawi, Ibrahim S; Baerson, Scott R

    2013-02-01

    Sorghum allelopathy has been reported in a series of field experiments following sorghum establishment. In recent years, sorghum phytotoxicity and allelopathic interference also have been well-described in greenhouse and laboratory settings. Observations of allelopathy have occurred in diverse locations and with various sorghum plant parts. Phytotoxicity has been reported when sorghum was incorporated into the soil as a green manure, when residues remained on the soil surface in reduced tillage settings, or when sorghum was cultivated as a crop in managed fields. Allelochemicals present in sorghum tissues have varied with plant part, age, and cultivar evaluated. A diverse group of sorghum allelochemicals, including numerous phenolics, a cyanogenic glycoside (dhurrin), and a hydrophobic p-benzoquinone (sorgoleone) have been isolated and identified in recent years from sorghum shoots, roots, and root exudates, as our capacity to analyze and identify complex secondary products in trace quantities in the plant and in the soil rhizosphere has improved. These allelochemicals, particularly sorgoleone, have been widely investigated in terms of their mode(s) of action, specific activity and selectivity, release into the rhizosphere, and uptake and translocation into sensitive indicator species. Both genetics and environment have been shown to influence sorgoleone production and expression of genes involved in sorgoleone biosynthesis. In the soil rhizosphere, sorgoleone is released continuously by living root hairs where it accumulates in significant concentrations around its roots. Further experimentation designed to study the regulation of sorgoleone production by living sorghum root hairs may result in increased capacity to utilize sorghum cover crops more effectively for suppression of germinating weed seedlings, in a manner similar to that of soil-applied preemergent herbicides like trifluralin.

  12. Chemical ecology of insect-plant interactions: ecological significance of plant secondary metabolites.

    Science.gov (United States)

    Nishida, Ritsuo

    2014-01-01

    Plants produce a diverse array of secondary metabolites as chemical barriers against herbivores. Many phytophagous insects are highly adapted to these allelochemicals and use such unique substances as the specific host-finding cues, defensive substances of their own, and even as sex pheromones or their precursors by selectively sensing, incorporating, and/or processing these phytochemicals. Insects also serve as pollinators often effectively guided by specific floral fragrances. This review demonstrates the ecological significance of such plant secondary metabolites in the highly diverse interactions between insects and plants.

  13. Feeding deterrent compounds to the boll weevil,Anthonomus grandis Boheman in Rose-of-Sharon,Hibiscus syriacus L.

    Science.gov (United States)

    Bird, T G; Hedin, P A; Burks, M L

    1987-05-01

    The Rose-of-Sharon,Hibiscus syriacus (L.), can be a significant alternate host plant for the boll weevil,Anthonomus gradis (Boh.). Boll weevils are known to be deterred from feeding and ovipositing in the buds unless the calyx is removed. This investigation was initiated to identify calyx allelochemicals that deter feeding with the eventual strategy of breeding for cotton lines high in these allelochemicals in the appropriate tissues. The feeding deterrency of calyx tissue from the buds of Rose-of-Sharon for the boll weevil was confirmed. The most active deterrent fraction was found to contain mostly fatty acids and their methyl esters. Saturated fatty acids and their methyl esters were generally found to be stimulatory, while the unsaturated species were found to be deterrent. Higher quantities of the fatty acids, particularly the unsaturated species, were found in Rose-of-Sharon calyx tissue than in the buds without calyx. This supports the hypothesis developed through the isolational work and testing of standards that the unsaturated fatty acids are significant deterrents of boll weevil feeding.

  14. Invasion waves in the biochemical warfare between living organisms

    Science.gov (United States)

    Carvalho, S. A.; Martins, M. L.

    2018-04-01

    Microorganisms and plants very commonly release toxic secondary chemical compounds (allelochemicals) that inhibit or kill sensitive strains or individuals from their own or other species. In this work we study a model that describes two species interacting through allelopathic suppression and competing for resources. Employing linear stability analysis, the conditions for coexistence or extinction of species in spatially homogeneous systems were determined. We found that the borders between the regimes of bistability, coexistence, and the extinction of the weaker by the stronger competitor, are altered by allelopathic interactions. In addition, traveling wave solutions for one species invasion were obtained considering the spatially explicit nature of the model. Our findings indicate that the minimum speed of the invasion wavefronts depends primarily on the competition coefficients and the parameters characterizing the species' functional responses to their allelochemicals. As a general rule, the species provided with the most effective chemical weapons dominates the population dynamics. Finally, we found a tristability at the coexistence region due to the combination of allelopathy and patchy population distributions in space. So, our model provides a distinct mechanism, independent of social behaviors, that produces such unexpected tristability impossible in classical competition models involving one-to-one individual interactions.

  15. Phenolics and Plant Allelopathy

    Directory of Open Access Journals (Sweden)

    De-An Jiang

    2010-12-01

    Full Text Available Phenolic compounds arise from the shikimic and acetic acid (polyketide metabolic pathways in plants. They are but one category of the many secondary metabolites implicated in plant allelopathy. Phenolic allelochemicals have been observed in both natural and managed ecosystems, where they cause a number of ecological and economic problems, such as declines in crop yield due to soil sickness, regeneration failure of natural forests, and replanting problems in orchards. Phenolic allelochemical structures and modes of action are diverse and may offer potential lead compounds for the development of future herbicides or pesticides. This article reviews allelopathic effects, analysis methods, and allelopathic mechanisms underlying the activity of plant phenolic compounds. Additionally, the currently debated topic in plant allelopathy of whether catechin and 8-hydroxyquinoline play an important role in Centaurea maculata and Centaurea diffusa invasion success is discussed. Overall, the main purpose of this review is to highlight the allelopacthic potential of phenolic compounds to provide us with methods to solve various ecology problems, especially in regard to the sustainable development of agriculture, forestry, nature resources and environment conservation.

  16. New insights on the species-specific allelopathic interactions between macrophytes and marine HAB dinoflagellates.

    Directory of Open Access Journals (Sweden)

    Hela Ben Gharbia

    Full Text Available Macrophytes are known to release allelochemicals that have the ability to inhibit the proliferation of their competitors. Here, we investigated the effects of the fresh leaves of two magnoliophytes (Zostera noltei and Cymodocea nodosa and thalli of the macroalgae Ulva rigida on three HAB-forming benthic dinoflagellates (Ostreopsis cf. ovata, Prorocentrum lima, and Coolia monotis. The effects of C. nodosa and U. rigida were also tested against the neurotoxic planktonic dinoflagellate Alexandrium pacificum Litaker sp. nov (former Alexandrium catenella. Co-culture experiments were conducted under controlled laboratory conditions and potential allelopathic effects of the macrophytes on the growth, photosynthesis and toxin production of the targeted dinoflagellates were evaluated. Results showed that U. rigida had the strongest algicidal effect and that the planktonic A. pacificum was the most vulnerable species. Benthic dinoflagellates seemed more tolerant to potential allelochemicals produced by macrophytes. Depending on the dinoflagellate/macrophyte pairs and the weight of leaves/thalli tested, the studied physiological processes were moderately to heavily altered. Our results suggest that the allelopathic activity of the macrophytes could influence the development of HAB species.

  17. New insights on the species-specific allelopathic interactions between macrophytes and marine HAB dinoflagellates.

    Science.gov (United States)

    Ben Gharbia, Hela; Kéfi-Daly Yahia, Ons; Cecchi, Philippe; Masseret, Estelle; Amzil, Zouher; Herve, Fabienne; Rovillon, Georges; Nouri, Habiba; M'Rabet, Charaf; Couet, Douglas; Zmerli Triki, Habiba; Laabir, Mohamed

    2017-01-01

    Macrophytes are known to release allelochemicals that have the ability to inhibit the proliferation of their competitors. Here, we investigated the effects of the fresh leaves of two magnoliophytes (Zostera noltei and Cymodocea nodosa) and thalli of the macroalgae Ulva rigida on three HAB-forming benthic dinoflagellates (Ostreopsis cf. ovata, Prorocentrum lima, and Coolia monotis). The effects of C. nodosa and U. rigida were also tested against the neurotoxic planktonic dinoflagellate Alexandrium pacificum Litaker sp. nov (former Alexandrium catenella). Co-culture experiments were conducted under controlled laboratory conditions and potential allelopathic effects of the macrophytes on the growth, photosynthesis and toxin production of the targeted dinoflagellates were evaluated. Results showed that U. rigida had the strongest algicidal effect and that the planktonic A. pacificum was the most vulnerable species. Benthic dinoflagellates seemed more tolerant to potential allelochemicals produced by macrophytes. Depending on the dinoflagellate/macrophyte pairs and the weight of leaves/thalli tested, the studied physiological processes were moderately to heavily altered. Our results suggest that the allelopathic activity of the macrophytes could influence the development of HAB species.

  18. Is Allelopathic Activity of Ipomoea murucoides Induced by Xylophage Damage?

    Science.gov (United States)

    Flores-Palacios, Alejandro; Corona-López, Angélica María; Rios, María Yolanda; Aguilar-Guadarrama, Berenice; Toledo-Hernández, Víctor Hugo; Rodríguez-López, Verónica; Valencia-Díaz, Susana

    2015-01-01

    Herbivory activates the synthesis of allelochemicals that can mediate plant-plant interactions. There is an inverse relationship between the activity of xylophages and the abundance of epiphytes on Ipomoea murucoides. Xylophagy may modify the branch chemical constitution, which also affects the liberation of allelochemicals with defense and allelopathic properties. We evaluated the bark chemical content and the effect of extracts from branches subjected to treatments of exclusion, mechanical damage and the presence/absence of epiphytes, on the seed germination of the epiphyte Tillandsia recurvata. Principal component analysis showed that branches without any treatment separate from branches subjected to treatments; damaged and excluded branches had similar chemical content but we found no evidence to relate intentional damage with allelopathy; however 1-hexadecanol, a defense volatile compound correlated positively with principal component (PC) 1. The chemical constitution of branches subject to exclusion plus damage or plus epiphytes was similar among them. PC2 indicated that palmitic acid (allelopathic compound) and squalene, a triterpene that attracts herbivore enemies, correlated positively with the inhibition of seed germination of T. recurvata. Inhibition of seed germination of T. recurvata was mainly correlated with the increment of palmitic acid and this compound reached higher concentrations in excluded branches treatments. Then, it is likely that the allelopathic response of I. murucoides would increase to the damage (shade, load) that may be caused by a high load of epiphytes than to damage caused by the xylophages.

  19. Is Allelopathic Activity of Ipomoea murucoides Induced by Xylophage Damage?

    Directory of Open Access Journals (Sweden)

    Alejandro Flores-Palacios

    Full Text Available Herbivory activates the synthesis of allelochemicals that can mediate plant-plant interactions. There is an inverse relationship between the activity of xylophages and the abundance of epiphytes on Ipomoea murucoides. Xylophagy may modify the branch chemical constitution, which also affects the liberation of allelochemicals with defense and allelopathic properties. We evaluated the bark chemical content and the effect of extracts from branches subjected to treatments of exclusion, mechanical damage and the presence/absence of epiphytes, on the seed germination of the epiphyte Tillandsia recurvata. Principal component analysis showed that branches without any treatment separate from branches subjected to treatments; damaged and excluded branches had similar chemical content but we found no evidence to relate intentional damage with allelopathy; however 1-hexadecanol, a defense volatile compound correlated positively with principal component (PC 1. The chemical constitution of branches subject to exclusion plus damage or plus epiphytes was similar among them. PC2 indicated that palmitic acid (allelopathic compound and squalene, a triterpene that attracts herbivore enemies, correlated positively with the inhibition of seed germination of T. recurvata. Inhibition of seed germination of T. recurvata was mainly correlated with the increment of palmitic acid and this compound reached higher concentrations in excluded branches treatments. Then, it is likely that the allelopathic response of I. murucoides would increase to the damage (shade, load that may be caused by a high load of epiphytes than to damage caused by the xylophages.

  20. Lichen secondary metabolites affect growth of Physcomitrella patens by allelopathy.

    Science.gov (United States)

    Goga, Michal; Antreich, Sebastian J; Bačkor, Martin; Weckwerth, Wolfram; Lang, Ingeborg

    2017-05-01

    Lichen secondary metabolites can function as allelochemicals and affect the development and growth of neighboring bryophytes, fungi, vascular plants, microorganisms, and even other lichens. Lichen overgrowth on bryophytes is frequently observed in nature even though mosses grow faster than lichens, but there is still little information on the interactions between lichens and bryophytes.In the present study, we used extracts from six lichen thalli containing secondary metabolites like usnic acid, protocetraric acid, atranorin, lecanoric acid, nortistic acid, and thamnolic acid. To observe the influence of these metabolites on bryophytes, the moss Physcomitrella patens was cultivated for 5 weeks under laboratory conditions and treated with lichen extracts. Toxicity of natural mixtures of secondary metabolites was tested at three selected doses (0.001, 0.01, and 0.1 %). When the mixture contained substantial amounts of usnic acid, we observed growth inhibition of protonemata and reduced development of gametophores. Significant differences in cell lengths and widths were also noticed. Furthermore, usnic acid had a strong effect on cell division in protonemata suggesting a strong impact on the early stages of bryophyte development by allelochemicals contained in the lichen secondary metabolites.Biological activities of lichen secondary metabolites were confirmed in several studies such as antiviral, antibacterial, antitumor, antiherbivore, antioxidant, antipyretic, and analgetic action or photoprotection. This work aimed to expand the knowledge on allelopathic effects on bryophyte growth.

  1. Interspecific competition and allelopathic interaction between Karenia mikimotoi and Dunaliella salina in laboratory culture

    Science.gov (United States)

    He, Dong; Liu, Jiao; Hao, Qiang; Ran, Lihua; Zhou, Bin; Tang, Xuexi

    2016-03-01

    Algal allelopathy is a manifold ecological/physiological phenomenon that is focused on chemical interactions and autotoxicity. We investigated the allelopathic interactions between Karenia mikimotoi and Dunaliella salina in laboratory cultures based on diff erent temperature (15°C, 20°C, and 25°C) and lighting (40, 80, and 160 μmol/(m2·s)) conditions. The growth of D. salina in bi-algae culture (1:1 size/density) was significantly restrained. The results of cell-free filtrate culture indicate that direct cell-tocell contact was not necessary in interspecific competition. Further experimental results demonstrated that allelochemicals released from K. mikimotoi were markedly influenced by both temperature ( P =0.013) and irradiance ( P =0.003), resulting in diff erent growth characteristics of D. salina in filtrate mediums. Compared with the plateau period, K. mikimotoi exudates in the exponential phase had a stronger short-term inhibition effect on D. salina in normal conditions. A clear concentration-dependent relationship was observed in the effect of allelochemicals released from K. mikimotoi with low-promoting and high-repressing effects on D. Salina in a short time-scale. In addition, allelopathic substances remain stable and effective under high temperature and pressure stress. Many flocculent sediments adhering with D. salina cells were observed in all filtrate mediums, while the quantity and color depended on the original culture conditions.

  2. Genome of the Asian longhorned beetle (Anoplophora glabripennis), a globally significant invasive species, reveals key functional and evolutionary innovations at the beetle-plant interface.

    Science.gov (United States)

    McKenna, Duane D; Scully, Erin D; Pauchet, Yannick; Hoover, Kelli; Kirsch, Roy; Geib, Scott M; Mitchell, Robert F; Waterhouse, Robert M; Ahn, Seung-Joon; Arsala, Deanna; Benoit, Joshua B; Blackmon, Heath; Bledsoe, Tiffany; Bowsher, Julia H; Busch, André; Calla, Bernarda; Chao, Hsu; Childers, Anna K; Childers, Christopher; Clarke, Dave J; Cohen, Lorna; Demuth, Jeffery P; Dinh, Huyen; Doddapaneni, HarshaVardhan; Dolan, Amanda; Duan, Jian J; Dugan, Shannon; Friedrich, Markus; Glastad, Karl M; Goodisman, Michael A D; Haddad, Stephanie; Han, Yi; Hughes, Daniel S T; Ioannidis, Panagiotis; Johnston, J Spencer; Jones, Jeffery W; Kuhn, Leslie A; Lance, David R; Lee, Chien-Yueh; Lee, Sandra L; Lin, Han; Lynch, Jeremy A; Moczek, Armin P; Murali, Shwetha C; Muzny, Donna M; Nelson, David R; Palli, Subba R; Panfilio, Kristen A; Pers, Dan; Poelchau, Monica F; Quan, Honghu; Qu, Jiaxin; Ray, Ann M; Rinehart, Joseph P; Robertson, Hugh M; Roehrdanz, Richard; Rosendale, Andrew J; Shin, Seunggwan; Silva, Christian; Torson, Alex S; Jentzsch, Iris M Vargas; Werren, John H; Worley, Kim C; Yocum, George; Zdobnov, Evgeny M; Gibbs, Richard A; Richards, Stephen

    2016-11-11

    Relatively little is known about the genomic basis and evolution of wood-feeding in beetles. We undertook genome sequencing and annotation, gene expression assays, studies of plant cell wall degrading enzymes, and other functional and comparative studies of the Asian longhorned beetle, Anoplophora glabripennis, a globally significant invasive species capable of inflicting severe feeding damage on many important tree species. Complementary studies of genes encoding enzymes involved in digestion of woody plant tissues or detoxification of plant allelochemicals were undertaken with the genomes of 14 additional insects, including the newly sequenced emerald ash borer and bull-headed dung beetle. The Asian longhorned beetle genome encodes a uniquely diverse arsenal of enzymes that can degrade the main polysaccharide networks in plant cell walls, detoxify plant allelochemicals, and otherwise facilitate feeding on woody plants. It has the metabolic plasticity needed to feed on diverse plant species, contributing to its highly invasive nature. Large expansions of chemosensory genes involved in the reception of pheromones and plant kairomones are consistent with the complexity of chemical cues it uses to find host plants and mates. Amplification and functional divergence of genes associated with specialized feeding on plants, including genes originally obtained via horizontal gene transfer from fungi and bacteria, contributed to the addition, expansion, and enhancement of the metabolic repertoire of the Asian longhorned beetle, certain other phytophagous beetles, and to a lesser degree, other phytophagous insects. Our results thus begin to establish a genomic basis for the evolutionary success of beetles on plants.

  3. Soil biota reduce allelopathic effects of the invasive Eupatorium adenophorum.

    Directory of Open Access Journals (Sweden)

    Xunzhi Zhu

    Full Text Available Allelopathy has been hypothesized to play a role in exotic plant invasions, and study of this process can improve our understanding of how direct and indirect plant interactions influence plant community organization and ecosystem functioning. However, allelopathic effects can be highly conditional. For example allelopathic effects demonstrated in vivo can be difficult to demonstrate in field soils. Here we tested phytotoxicity of Eupatorium adenophorum (croftonweed, one of the most destructive exotic species in China, to a native plant species Brassica rapa both in sand and in native soil. Our results suggested that natural soils from different invaded habitats alleviated or eliminated the efficacy of potential allelochemicals relative to sand cultures. When that soil is sterilized, the allelopathic effects returned; suggesting that soil biota were responsible for the reduced phytotoxicity in natural soils. Neither of the two allelopathic compounds (9-Oxo-10,11-dehydroageraphorone and 9b-Hydroxyageraphorone of E. adenophorum could be found in natural soils infested by the invader, and when those compounds were added to the soils as leachates, they showed substantial degradation after 24 hours in natural soils but not in sand. Our findings emphasize that soil biota can reduce the allelopathic effects of invaders on other plants, and therefore can reduce community invasibility. These results also suggest that soil biota may have stronger or weaker effects on allelopathic interactions depending on how allelochemicals are delivered.

  4. Tolerance induction to stress caused by lavender (Lavandula angustifolia extracts in the microalga Dunaliella salina through metabolic modifications and β-carotene production

    Directory of Open Access Journals (Sweden)

    Sahar Mazang-Ghasemi

    2016-03-01

    Full Text Available The inhibitory or stimulatory effect of one plant on other plant species through the released chemical compounds into the environment, known as allelochemicals, is called allelopathy. In the present study, effect of aqueous extracts of lavender (Lavandula angustifolia leaves on growth pattern and ability of β-carotene production in unicellular green alga, Dunaliella salina was investigated. Based on these results, phenolics content and antioxidant capacity of the extracts was relatively low. Treated cultures with extract concentrations of 1, 2, 3 and 4 % showed that the process of cell division was ceased because of extracts phytotoxicity. However, the chlorophyll and β-carotene concentration pronouncedly increased in phytotoxin-treated cells, so that the highest of these values were detected in 3 % extracts-exposed cells. Percentage change of all three fresh weight, total sugar and protein between 0 and 48 h of phytotoxins treatment was significantly increased concurrently with increasing dose of extracts. These results suggest that D. salina tolerate allelochemicals-induced stress by metabolic modifications. Therefore, phytotoxins-tolerance mechanisms in D. salina are associated with physiological and metabolic adjustments by allocating the carbon flux to the synthesis of the sugars, chlorophyll and β-carotene, which induce phytotoxins stress tolerance in this alga.

  5. Soil biota reduce allelopathic effects of the invasive Eupatorium adenophorum.

    Science.gov (United States)

    Zhu, Xunzhi; Zhang, Jintun; Ma, Keping

    2011-01-01

    Allelopathy has been hypothesized to play a role in exotic plant invasions, and study of this process can improve our understanding of how direct and indirect plant interactions influence plant community organization and ecosystem functioning. However, allelopathic effects can be highly conditional. For example allelopathic effects demonstrated in vivo can be difficult to demonstrate in field soils. Here we tested phytotoxicity of Eupatorium adenophorum (croftonweed), one of the most destructive exotic species in China, to a native plant species Brassica rapa both in sand and in native soil. Our results suggested that natural soils from different invaded habitats alleviated or eliminated the efficacy of potential allelochemicals relative to sand cultures. When that soil is sterilized, the allelopathic effects returned; suggesting that soil biota were responsible for the reduced phytotoxicity in natural soils. Neither of the two allelopathic compounds (9-Oxo-10,11-dehydroageraphorone and 9b-Hydroxyageraphorone) of E. adenophorum could be found in natural soils infested by the invader, and when those compounds were added to the soils as leachates, they showed substantial degradation after 24 hours in natural soils but not in sand. Our findings emphasize that soil biota can reduce the allelopathic effects of invaders on other plants, and therefore can reduce community invasibility. These results also suggest that soil biota may have stronger or weaker effects on allelopathic interactions depending on how allelochemicals are delivered.

  6. Sequential diets, metabolic costs, and growth of Spodoptera eridania (Lepidoptera: Noctuidae) feeding upon dill, lima bean, and cabbage.

    Science.gov (United States)

    Scriber, J Mark

    1981-01-01

    This study illustrates the diversity of feeding responses of individually polyphagous southern armyworms, Spodoptera eridania, to plants with differing allelochemics. In spite of the near optimal leaf water and nitrogen contents of the young foliage, it is apparent that vastly different larval growth performance results from dill, lima bean, and cabbage. Cabbage is the poorest food (as measured by larval growth rates and metabolic costs of processing the plant biomass). Unlike the case with certain other plant species or cultivars that are costly to process, with cabbage, S. eridania does not compensate for low efficiencies (E.C.D.'s) with increased consumption rates (R.C.R.'s). Biochemical or physiological reasons for this inability are unknown.A sequence of foods (changed each 18-24 h) apparently did not add sufficient stress upon the MFO system to be detected in the respiratory expenditures of S. eridania larvae, in spite of the fact that dill is known to contain insecticidal and synergistic chemicals (Lichtenstein et al. 1974). The larval growth performances and metabolic expenditures in these sequences were intermediate between the best food (dill) and the worse (cabbage). Significant differences were observed however between the sequential switching sequences, perhaps indicating that particular periods during the instar are especially more sensitive to certain allelochemics. Actual respiratory costs of the lima bean-cabbage-dill (i.e. B-C-D) sequence were 40-50% higher than observed for the other two sequences and more than 50% higher than the theoretical metabolic costs based on the proportions actually eaten and known costs associated with each food.This study and a related one (Scriber 1981a) illustrate how consumption rates, feeding efficiences, and larval growth of Spodoptera eridania are not species, population, or even individual characteristics, (cf. Fox and Morrow 1981), but instead depend largely upon variations in plant allelochemics and plant

  7. Patch colonization by Trirhabda canadensis (Coleoptera: Chrysomelidae): effects of plant species composition and wind.

    Science.gov (United States)

    Morrow, P A; Tonkyn, D W; Goldburg, R J

    1989-10-01

    The goldenrod leaf beetle, Trirhabda canadensis, is known to respond to odors of host and non-host species in the laboratory. Here we report movements of T. canadensis in the field in response to volatile odors from monocultures and polycultures of host plants. Overall, beetles preferentially colonized plots with a higher density of host plants and lower diversity of allelochemicals, but under some wind conditions there were marked exceptions. At high windspeeds, they colonized whichever plot(s) was upwind. At low windspeeds, beetles colonized preferred plots even when they were not upwind. The data suggest that odor dispersion varies in a complex way with windspeed: at low windspeeds beetles received information from a wide are of vegetation and made choices while at high windspeeds information was available only from upwind plot(s).

  8. Allelopathic interactions between the red-tide causative dinoflagellate Prorocentrum donghaiense and the diatom Phaeodactylum tricornutum* This study was supported by the Natural Science Foundation of China-Guangdong Province Joint Key Project (U1133003 Science Technology Planning Project of Guangdong Province (2012B020307009 Open Fund from Key Laboratory of Aquatic Eutrophication Control of Harmful Algal Blooms of Guangdong Higher Education Institutes Open Fund from Key Laboratory of Microbial Resources Collection Preservation Ministry of Agriculture.

    Directory of Open Access Journals (Sweden)

    Zhuoping Cai

    2014-06-01

    Full Text Available The interactions between the red-tide causing dinoflagellate Prorocentrum donghaiense and the marine diatom Phaeodactylum tricornutum were investigated using a co-culture experiment and an enriched culture filtrate experiment. The results showed that when the two microalgae were cultured together with different initial cell densities, the growth of one species was basically suppressed by the other one. In addition, the enriched culture filtrates of one species had generally inhibitory effects on the other one. Our result inferred that P. donghaiense and P. tricornutum would interfere with each other mainly by releasing allelochemicals into the culture medium, and that the degree of allelopathic effects was dependent on the initial cell densities and growth phases. The allelopathic interactions between microalgal species may contribute to the formation and succession of red tides.

  9. Potential improvement of Lymantria dispar L. management by quercetin

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    Perić-Mataruga Vesna

    2014-01-01

    Full Text Available Lymantria dispar, a polyphagous insect pest, copes with a wide variety of host-specific allelochemicals. Glutathione S-transferases (GST are important for catalyzing detoxification in L. dispar. Larval mortality, GST activity in midgut tissue and mass of L. dispar with different trophic adaptations (originating from two forests with a suitable host, Quercus robur, and an unsuitable host, Robinia pseudoacacia, differed after feeding on quercetin supplemented diets (2% or 5% w/w. Quercetin inhibited GST most potently in oak forest larvae that were less adapted to flavonoids in their diet. The larvicidal effect of quercetin on L. dispar larvae depended on the host-use history. We believe this is important in strategies for sustainable control of insect pests. [Projekat Ministarstva nauke Republike Srbije, br. 173027

  10. Allelopathic activity and chemical constituents of walnut (Juglans regia) leaf litter in walnut-winter vegetable agroforestry system.

    Science.gov (United States)

    Wang, Qian; Xu, Zheng; Hu, Tingxing; Rehman, Hafeez Ur; Chen, Hong; Li, Zhongbin; Ding, Bo; Hu, Hongling

    2014-01-01

    Walnut agroforestry systems have many ecological and economic benefits when intercropped with cool-season species. However, decomposing leaf litter is one of the main sources of allelochemicals in such systems. In this study, lettuce (Lactuca sativa var. angustata) was grown in the soil incorporated with walnut leaf litter to assess its allelopathic activity. Lettuce growth and physiological processes were inhibited by walnut leaf litter, especially during early growth stage (1-2 euphylla period) or with large amount of litter addition. The plants treated by small amount of leaf litter recovered their growth afterwards, while the inhibition for 180 g leaf litter persisted until harvest. Twenty-eight compounds were identified in the leaf litter, and several of them were reported to be phytotoxic, which may be responsible for the stress induced by walnut leaf litter. Thus, for highest economic value of vegetables such as lettuce, excessive incorporation of leaf litter should be discouraged.

  11. Mechanism of artemisinin phytotoxicity action: induction of reactive oxygen species and cell death in lettuce seedlings.

    Science.gov (United States)

    Yan, Zhi-Qiang; Wang, Dan-Dan; Ding, Lan; Cui, Hai-Yan; Jin, Hui; Yang, Xiao-Yan; Yang, Jian-She; Qin, Bo

    2015-03-01

    Artemisinin has been recognized as an allelochemical that inhibits growth of several plant species. However, its mode of action is not well clarified. In this study, the mechanism of artemisinin phytotoxicity on lettuce seedlings was investigated. Root and shoot elongation of lettuce seedlings were inhibited by artemisinin in a concentration-dependent manner. The compound effectively arrested cell division and caused loss of cell viability in root tips of lettuce. Overproduction of reactive oxygen species (ROS) was induced by artemisinin. Lipid peroxidation, proline overproduction and reduction of chlorophyll content in lettuce seedlings were found after treatments. These results suggested that artemisinin could induce ROS overproduction, which caused membrane lipids peroxidation and cell death, and impacted mitosis and physiological processes, resulting in growth inhibition of receptor plants. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  12. [Progress in improvement of continuous monoculture cropping problem in Panax ginseng by controlling soil-borne disease management].

    Science.gov (United States)

    Wang, Rui; Dong, Lin-Lin; Xu, Jiang; Chen, Jun-Wen; Li, Xi-Wen; Chen, Shi-Lin

    2016-11-01

    The continuous monoculture cropping problem severely has hindered the land resource of Panax ginseng cultivation and threatened the sustainable development of ginseng industry. There are comprehensive factors causing the continuous monoculture cropping problem, such as deterioration of soil physical and chemical properties, accumulation of allelochemical, increase of pesticide residue and heavy metal, imbalance of rhizospheric micro-ecosystem, and increase of soil-borne diseases. Among soil-borne disease was one of the key factors. More than 40 soil-borne diseases have been reported in the ginseng cultivation, especially, the diseases were more serious in the ginseng replanting land. Here main soil-borne diseases and their prevention way have been summarized, and we try to provide the effective improvement strategy of continuous monoculture cropping problem focusing on the disease control and offer reference for overcoming the ginseng continuous monoculture cropping problem. Copyright© by the Chinese Pharmaceutical Association.

  13. AtMRP1 gene of Arabidopsis encodes a glutathione S-conjugate pump: isolation and functional definition of a plant ATP-binding cassette transporter gene.

    Science.gov (United States)

    Lu, Y P; Li, Z S; Rea, P A

    1997-07-22

    Because plants produce cytotoxic compounds to which they, themselves, are susceptible and are exposed to exogenous toxins (microbial products, allelochemicals, and agrochemicals), cell survival is contingent on mechanisms for detoxifying these agents. One detoxification mechanism is the glutathione S-transferase-catalyzed glutathionation of the toxin, or an activated derivative, and transport of the conjugate out of the cytosol. We show here that a transporter responsible for the removal of glutathione S-conjugates from the cytosol, a specific Mg2+-ATPase, is encoded by the AtMRP1 gene of Arabidopsis thaliana. The sequence of AtMRP1 and the transport capabilities of membranes prepared from yeast cells transformed with plasmid-borne AtMRP1 demonstrate that this gene encodes an ATP-binding cassette transporter competent in the transport of glutathione S-conjugates of xenobiotics and endogenous substances, including herbicides and anthocyanins.

  14. Main Alkaloids of Peganum harmala L. and Their Different Effects on Dicot and Monocot Crops

    Directory of Open Access Journals (Sweden)

    Chi Zhang

    2013-02-01

    Full Text Available Alkaloids with allelopathic activity are not as well-known as other allelochemicals. Our study revealed that total alkaloids from seeds of the medicinal plant Peganum harmala L. possessed significant growth inhibitory effect on four treated plants, with dicot plants (lettuce and amaranth being more sensitive than the tested monocot plants (wheat and ryegrass. Further investigation led to the isolation of harmaline and harmine as the main active ingredients in the total alkaloids of P. harmala seeds. Harmaline exerted potent inhibitory effects on seedling growth of treated plants, especially dicots, inhibiting root elongation of lettuce and amaranth by 31% and 47% at a very low concentration (5 µg/mL, whereas harmine exhibited much weaker non-selective inhibitory effect on the plants. Considering the high yield and poor utilization of P. harmala in China, we anticipate that this plant could be exploited as an alternative weed management tool in the future.

  15. Current Research Status of Allelopathy

    Directory of Open Access Journals (Sweden)

    AHMAD JUNAEDI

    2006-06-01

    Full Text Available The term of allelopathy refers to chemical interactions (inhibitory or stimulatory between plants, between plants and microorganisms, and between microorganisms. The wealth of information on the processes, procedures, and practices of allelopathy has contributed to understanding this field of science. Recently, researches of allelopathy have been conducted in laboratory, greenhouse, and field with multifaceted standpoint in some concerning area: (i allelochemicals identifications and screening test; (ii ecological and physiological aspects of allelopathy; (iii genetic studies and the possibilities of using plant breeding or genetic manipulation to enhance allelopathic varieties; (iv the use of allelopathic potential in the biological control, including as natural pesticide, of weeds and plant diseases as eco-friendly approach for sustainable agriculture scheme.

  16. Structure-dependent phytotoxicity of catechins and other flavonoids: flavonoid conversions by cell-free protein extracts of Centaurea maculosa (spotted knapweed) roots.

    Science.gov (United States)

    Bais, Harsh Pal; Walker, Travis S; Kennan, Alan J; Stermitz, Frank R; Vivanco, Jorge M

    2003-02-12

    Invasive plants are believed to succeed in part by secretion of allelochemicals, thus displacing competing plant species. Centaurea maculosa (spotted knapweed) provides a classic example of this process. We have previously reported that spotted knapweed roots secrete (+/-)-catechin and that (-)-catechin, but not (+)-catechin, is phytotoxic and hence may be a major contributor to C. maculosa's invasive behavior in the rhizosphere. In this communication, we explore both structure/activity relationships for flavonoid phytotoxicity and possible biosynthetic pathways for root production of (+/-)-catechin. Kaempferol and dihydroquercetin were shown to be phytotoxic, while quercetin was not. Kaempferol was converted to dihydroquercetin and (+/-)-catechin when treated with total root protein extracts from C. maculosa, but quercetin was not. This finding suggests an alteration in the standard flavonoid biosynthetic pathway in C. maculosa roots, whereby kaempferol is not a dead-end product but serves as a precursor to dihydroquercetin, which in turn leads to (+/-)-catechin production.

  17. Codonopilate A, a Triterpenyl Ester as Main Autotoxin in Cultivated Soil of Codonopsis pilosula (Franch.) Nannf.

    Science.gov (United States)

    Xie, Min; Yan, Zhiqiang; Ren, Xia; Li, Xiuzhuang; Qin, Bo

    2017-03-15

    Codonopilate A (1), a triterpenyl ester, was isolated from monocultivated soil of annual Codonopsis pilosula and identified as the main autotoxin. The yield ratio of codonopilate A in dried soil was calculated as 2.04 μg/g. Other two triterpenoids, taraxeryl acetate (2) and 24-methylenecycloartanol (3), were isolated and identified as well showing weaker autotoxity. This was the first time that the potential allelochemicals and autotoxins in the cultivated soil of Codonopsis pilosula were reported. Accumulation of reactive oxygen species (ROS) induced by the autotoxins in the root tips of Codonopsis pilosula was considered as an important factor for the phytotoxic effect. This work systematically investigates the allelopathic and autotoxic effect of Codonopsis pilosula, and the preliminary autotoxic action mode of the three autotoxins. These findings are helpful to understand the molecular mechanism of autotoxicity and conducive to explore proper ways to degrade the autotoxins and eliminate the replanting problems of Codonopsis pilosula.

  18. Allelopathic potential of digera muricata, a desert summer annual

    International Nuclear Information System (INIS)

    Aziz, S.; Shahid, S.; Shaukat, S.

    2014-01-01

    Allelopathic potential of Digera muricata was tested on different crops by germinating them in different concentrations of D. muricata extract. It was observed that germination of all test species were highly affected in the higher concentration of D. muricata extract. Bulrush-millet was the most affected species. Decaying plant material of D. muricata was also found to be highly phytotoxic. Maximum reduction in growth of bulrush-millet was observed in the decaying root material. Phenolic compounds (Quercetin, sinapic and ferluic acid), alkaloids (cystine and berbine) and a terpenoid (limonene) were detected from roots and shoots of D. muricata, Greater quantities of all these allelochemicals were present in the roots followed by shoots. (author)

  19. Inter-plant communication through mycorrhizal networks mediates complex adaptive behaviour in plant communities.

    Science.gov (United States)

    Gorzelak, Monika A; Asay, Amanda K; Pickles, Brian J; Simard, Suzanne W

    2015-05-15

    Adaptive behaviour of plants, including rapid changes in physiology, gene regulation and defence response, can be altered when linked to neighbouring plants by a mycorrhizal network (MN). Mechanisms underlying the behavioural changes include mycorrhizal fungal colonization by the MN or interplant communication via transfer of nutrients, defence signals or allelochemicals. We focus this review on our new findings in ectomycorrhizal ecosystems, and also review recent advances in arbuscular mycorrhizal systems. We have found that the behavioural changes in ectomycorrhizal plants depend on environmental cues, the identity of the plant neighbour and the characteristics of the MN. The hierarchical integration of this phenomenon with other biological networks at broader scales in forest ecosystems, and the consequences we have observed when it is interrupted, indicate that underground 'tree talk' is a foundational process in the complex adaptive nature of forest ecosystems. Published by Oxford University Press on behalf of the Annals of Botany Company.

  20. Multiorganismal insects: diversity and function of resident microorganisms.

    Science.gov (United States)

    Douglas, Angela E

    2015-01-07

    All insects are colonized by microorganisms on the insect exoskeleton, in the gut and hemocoel, and within insect cells. The insect microbiota is generally different from microorganisms in the external environment, including ingested food. Specifically, certain microbial taxa are favored by the conditions and resources in the insect habitat, by their tolerance of insect immunity, and by specific mechanisms for their transmission. The resident microorganisms can promote insect fitness by contributing to nutrition, especially by providing essential amino acids, B vitamins, and, for fungal partners, sterols. Some microorganisms protect their insect hosts against pathogens, parasitoids, and other parasites by synthesizing specific toxins or modifying the insect immune system. Priorities for future research include elucidation of microbial contributions to detoxification, especially of plant allelochemicals in phytophagous insects, and resistance to pathogens; as well as their role in among-insect communication; and the potential value of manipulation of the microbiota to control insect pests.

  1. Quantitative Trait Loci Analysis of Allelopathy in Rice

    DEFF Research Database (Denmark)

    Jensen, L B; Courtois, B; Olofsdotter, M

    2008-01-01

    The allelopathic potential of rice (Oryza sativa L.) against Echinochloa crus-galli (L.) Beauv. was investigated under both laboratory and greenhouse conditions. A population of 150 recombinant inbred lines (RILs) was derived through single-seed descent from a cross between the indica cultivar AC...... the population phenotype was normally distributed. Two quantitative trait loci (QTLs) were located on chromosomes 4 and 7, explaining 20% of the phenotypic variation. A second relay seeding experiment was set up, this time including charcoal in the perlite. This screening showed that the allelopathic rice...... varieties did not have any effect on the weed species when grown with charcoal, the charcoal reversing the effect of any potential allelochemicals exuded from the rice roots. The second phenotypic experiment was conducted under greenhouse conditions in pots. Thirteen QTLs were detected for four different...

  2. Allelopathic potential of Artemisia arborescens: isolation, identification and quantification of phytotoxic compounds through fractionation-guided bioassays.

    Science.gov (United States)

    Araniti, Fabrizio; Lupini, Antonio; Sorgonà, Agostino; Conforti, Filomena; Marrelli, Mariangela; Statti, Giancarlo Antonio; Menichini, Francesco; Abenavoli, Maria Rosa

    2013-01-01

    The aerial part of Artemisia arborescens L. (Asteraceae) was extracted with water and methanol, and both extracts were fractionated using n-hexane, chloroform, ethyl acetate and n-butanol. The potential phytotoxicity of both crude extracts and their fractions were assayed in vitro on seed germination and root growth of lettuce (Lactuca sativa L.), a sensitive species largely employed in the allelopathy studies. The inhibitory activities were analysed by dose-response curves and the ED 50 were estimated. Crude extracts strongly inhibited both germination and root growth processes. The fraction-bioassay indicated the following hierarchy of phytotoxicity for both physiological processes: ethyl acetate ≥ n-hexane > chloroform ≥ n-butanol. On the n-hexane fraction, GC-MS analyses were carried out to characterise and quantify some of the potential allelochemicals. Twenty-one compounds were identified and three of them, camphor, trans-caryophyllene and pulegone were quantified.

  3. Evaluation of the allelopathic potential of water-soluble compounds of barley (Hordeum vulgare L. subsp.vulgare and great brome (Bromus diandrus Roth. using a modified bioassay

    Directory of Open Access Journals (Sweden)

    Bouhaouel, I.

    2016-01-01

    Full Text Available Description of the subject. The present study focuses on the description of the allelopathic interactions between wild and crop species that may occur in a given ecosystem. Objectives. The objective is the evaluation of the allo- and autoinhibition activity of root exudates of barley (Hordeum vulgare L. subsp. vulgare and great brome (Bromus diandrus Roth. seedlings by water-soluble allelochemicals. Method. The allelopathic activities of five Tunisian barley genotypes (modern varieties and landraces, one Saudi Arabian barley landrace and great brome were assessed using a modified laboratory bioassay named "seedling-after-seedling agar method". Results. The barley or the great brome reduced, to a greater extent, the root growth compared to the shoot growth of receiver species. The response of the root system architecture of the great brome towards barley root exudates was studied in detail. All the measured root traits were highly sensitive to the presence of barley. In our conditions, the allelopathic activity of barley root exudates had no apparent relationship with the size of the root and a prominent action of genetic determinants in the allelopathic potential between genotypes is proposed. The alloinhibitory activity of barley or great brome root exudates deferred between the receiver species but was always higher than the autoinhibition potential. The autoinhibition in barley proved to depend on whether the genotypes used as donor and receiver are identical or different, suggesting a specific interaction of allelochemicals with the receiver plant. These molecules seem to be the main actors in the allelopathic barley potential as external factors such variations of pH have no evident relevance in the inhibition process. Conclusions. Barley and great brome exude molecules in their surroundings. This affects the growth of the receiver plants, suggesting that these compounds might contribute to the plant community dynamics.

  4. Gene expression patterns of the coral Acropora millepora in response to contact with macroalgae

    Science.gov (United States)

    Shearer, T. L.; Rasher, D. B.; Snell, T. W.; Hay, M. E.

    2012-12-01

    Contact with macroalgae often causes coral mortality, but the roles of abrasion versus shading versus allelopathy in these interactions are rarely clear, and effects on gene expression are unknown. Identification of gene expression changes within corals in response to contact with macroalgae can provide insight into the mode of action of allelochemicals, as well as reveal transcriptional strategies of the coral that mitigate damage from this competitive interaction, enabling the coral to survive. Gene expression responses of the coral Acropora millepora after long-term (20 days) direct contact with macroalgae ( Chlorodesmis fastigiata, Dictyota bartayresiana, Galaxaura filamentosa, and Turbinaria conoides) and short-term (1 and 24 h) exposure to C. fastigiata thalli and their hydrophobic extract were assessed. After 20 days of exposure, T. conoides thalli elicited no significant change in visual bleaching or zooxanthellae PSII quantum yield within A. millepora nubbins, but stimulated the greatest alteration in gene expression of all treatments. Chlorodesmis fastigiata, D. bartayresiana, and G. filamentosa caused significant visual bleaching of coral nubbins and reduced the PSII quantum yield of associated zooxanthellae after 20 days, but elicited fewer changes in gene expression relative to T. conoides at day 20. To evaluate initial molecular processes leading to reduction of zooxanthella PSII quantum yield, visual bleaching, and coral death, short-term exposures to C. fastigiata thalli and hydrophobic extracts were conducted; these interactions revealed protein degradation and significant changes in catalytic and metabolic activity within 24 h of contact. These molecular responses are consistent with the hypothesis that allelopathic interactions lead to alteration of signal transduction and an imbalance between reactive oxidant species production and antioxidant capabilities within the coral holobiont. This oxidative imbalance results in rapid protein degradation

  5. Consumption and utilization of experimentally altered corn by southern armyworm: Iron, nitrogen, and cyclic hydroxamates.

    Science.gov (United States)

    Manuwoto, S; Scriber, J M

    1985-11-01

    The effects of differential leaf water, leaf nitrogen and cyclic hydroxamate (DIMBOA) concentrations in corn seedlings were analyzed for a polyphagous insect, the southern armyworm (Spodoptera eridania Cram.). Six different combinations of nutrients and allelochemicals [DIMBOA = 2,4-dihydroxy-7-methoxy(2H)-benzoxazin-3(4H)-one] were generated using two corn genotypes (WF9 and CI3IA) and three fertility regimes (complete nutrient, Fe-deficient, and N-deficient solutions) in the University Biotron. Poorest larval growth was observed in the low-nitrogen treatments (1.2% and 1.7% leaf N) and was the result of both low consumption rates and high metabolic costs (low efficiency of conversion of digested food, ECD). Fastest growth rates were observed forthe larvae fed leaves from the high-nitrogen treatments (4.6% and 4.4% leaf N). It is noteworthy that these treatments also contained the highest concentration of cyclic hydroxamates, which are generally believed to be the primary defensive chemicals mediating resistance against the European corn borer,Ostrinia nubilalis (Hubner). If these hydroxamates do have any deleterious or costly effects (perhaps accounting for a large portion of metabolic expenditures), the high digestibility of the leaf tissue and the increased consumption rates more than compensate, resulting in rapid growth (growth rate = consumption rate × approximate digestibility × efficiency of conversion of the digested food). These studies illustrate that variation in key nutrients and allelochemicals within a single plant species (Zea mays L.) may have significantly different effects upon various potential leaf-chewing caterpillars, such as these armyworms versus corn borers (which cannot handle the cyclic hydroxamates, even if provided with young nutritious leaf tissues).

  6. Evaluation of allelopathic potential of safflower genotypes (Carthamus tinctorius L.

    Directory of Open Access Journals (Sweden)

    Motamedi Marzieh

    2016-12-01

    Full Text Available Forty safflower genotypes were grown under normal irrigation and drought stress. In the first experiment, the allelopathic potential of shoot residues was evaluated using the sandwich method. Each genotype residue (0.4 g was placed in a sterile Petri dish and two layers of agar were poured on that. Radish seeds were placed on agar medium. The radish seeds were cultivated without safflower residues as the controls. The length of the radicle, hypocotyl, and fresh biomass weight and seed germination percentages were measured. A pot experiment was also done on two genotypes with the highest and two with the lowest allelopathic activity selected after screening genotypes in the first experiment. Before entering the reproductive phase, irrigation treatments (normal irrigation and drought stress were applied. Shoots were harvested, dried, milled and mixed with the topsoil of new pots and then radish seeds were sown. The pots with safflower genotypes were used to evaluate the effect of root residue allelopathy. The shoot length, fresh biomass weight, and germination percentage were measured. Different safflower genotypes showed varied allelopathic potential. The results of the first experiment showed that Egypt and Iran-Khorasan genotypes caused maximum inhibitory responses and Australia and Iran-Kerman genotypes resulted in minimum inhibitory responses on radish seedling growth. Fresh biomass weight had the most sensitivity to safflower residues. The results of the pot experiment were consistent with the results of in vitro experiments. Residues produced under drought stress had more inhibitory effects on the measured traits. Safflower root residue may have a higher level of allelochemicals or different allelochemicals than shoot residue.

  7. Allelopathic cover crop of rye for integrated weed control in sustainable agroecosystems

    Directory of Open Access Journals (Sweden)

    Vincenzo Tabaglio

    2013-02-01

    Full Text Available The allelopathic potential of rye (Secale cereale L. is mainly due to phytotoxic benzoxazinones, compounds that are produced and accumulated in young tissues to different degrees depending on cultivar and environmental influences. Living rye plants exude low levels of benzoxazinones, while cover crop residues can release from 12 to 20 kg ha–1. This paper summarizes the results obtained from several experiments performed in both controlled and field environments, in which rye was used as a cover crop to control summer weeds in a following maize crop. Significant differences in benzoxazinoid content were detected between rye cultivars. In controlled environments, rye mulches significantly reduced germination of some broadleaf weeds. Germination and seedling growth of Amaranthus retroflexus and Portulaca oleracea were particularly affected by the application of rye mulches, while Chenopodium album was hardly influenced and Abutilon theophrasti was advantaged by the presence of the mulch. With reference to the influence of agronomic factors on the production of benzoxazinoids, nitrogen fertilization increased the content of allelochemicals, although proportionally less than dry matter. The field trial established on no-till maize confirmed the significant weed suppressiveness of rye mulch, both for grass and broadleaf weeds. A significant positive interaction between nitrogen (N fertilization and notillage resulting in the suppression of broadleaf weeds was observed. The different behavior of the weeds in the presence of allelochemicals was explained in terms of differential uptake and translocation capabilities. The four summer weeds tested were able to grow in the presence of low amounts of benzoxazolin-2(3H-one (BOA, between 0.3 and 20 mmol g–1 fresh weight. Although there were considerable differences in their sensitivity to higher BOA concentrations, P. oleracea, A. retroflexus, and Ch. album represented a group of species with a consistent

  8. Anatomia e histoquímica das folhas de Senna alata Anatomy and histochemistry of Senna alata leaves

    Directory of Open Access Journals (Sweden)

    I.M.C. Rodrigues

    2009-01-01

    Full Text Available Senna alata é uma espécie daninha frequente em pastagens da região amazônica, cujas folhas apresentam propriedades medicinais. Indivíduos dessa espécie foram cultivados e coletados no Campo Experimental da Embrapa Amazônia Oriental, em Belém-PA, para a realização de análises anatômica e histoquímica das folhas, com a finalidade de fornecer elementos para a taxonomia, identificação microscópica de aleloquímicos e caracterização ecofisiológica da espécie. As folhas apresentaram duas formas de tricomas: tectores e glandulares. Outras características foliares encontradas na espécie foram: lâmina foliar anfiestomática, mesofilo dorsiventral e epiderme abaxial papilosa. Algumas dessas características sugerem um mecanismo de adaptação a ambientes com excesso de calor. As folhas são ricas em cristais de oxalato de cálcio, ao longo de suas nervuras - característica da subfamília Caesalpinioideae. Compostos fenólicos, como flavonoides e antraquinonas, foram encontrados em células epidérmicas, da base de tricomas, e células dispersas no parênquima paliçádico, especialmente nas proximidades da nervura mediana. Este estudo confirmou a presença de conhecidas classes de aleloquímicos em diferentes tipos de células do mesofilo de Senna alata.Senna alata is one of the most frequent weed species in the Amazonian region pastures. Its leaves present medicinal properties. Individuals of this species were cultivated and collected in the Experimental Field of Embrapa Amazônia Oriental, Belém-PA, to carry out anatomical and histochemical analyses to provide taxonomy information, microscopic identification of allelochemicals and ecophysiological characterization of the species. Leaves presented two forms of trichomes: tector and glandular. Other foliar characteristics of the species were: amphistomatic leaf, dorsiventral mesophyll and abaxial epidermis papillose. Some of these suggest an adaptation mechanism to excessive warm

  9. Allelopathic effects of aqueous extracts of sunflower on wheat (triticum aestivum l.) and maize (zea mays l.)

    International Nuclear Information System (INIS)

    Muhammad, Z.; Mujeed, A.

    2014-01-01

    Sunflower is a potent allelopathic plant which possesses important allelochemicals with known allelopathic activity on other plants. In this study, allelopathic effects of fresh aqueous extracts (FAE) and air dried aqueous extracts (DAE) of root, shoot and leaves of sunflower (Halianthus annuus L.) were investigated on germination and seedling growth of wheat (Triticum aestivum L.) and maize (Zea mays L.) in seed bioassay experiments carried out at Botany Department of Peshawar University during 2010. Results showed significantly inhibitory effects of aqueous extracts on seed germination, growth and dry biomass of seedlings of wheat and maize. In wheat seedlings, significant germination inhibition (15.21%), increased mean germination time (MGT) (57.76%), reduced plumule and radical growth (21.66 and 28.44%) and lowered seedlings dry biomass (31.05%) were recorded under dry aqueous extracts of leaf when compared to control. Germination percentage of maize was inhibited by dry aqueous extracts of leaf by 7.81%, germination index by 16.51%, increased MGT by 25.53%, decreased plumule and radical lengths by 29.00 and 36.12% respectively, and lowered maize seedling dry biomass by 34.02 %. In both experiments, dry aqueous extracts (DAE) were more phytotoxic than fresh aqueous extracts (FAE). Similarly, inhibitory effects of aqueous extracts of different parts of sunflower were recorded in the order leaf > shoot > root for both tested plants. (author)

  10. Determination of the genotoxic effects of Convolvulus arvensis extracts on corn (Zea mays L.) seeds.

    Science.gov (United States)

    Sunar, Serap; Yildirim, Nalan; Aksakal, Ozkan; Agar, Guleray

    2013-06-01

    In this research, the methanolic extracts of Convolvulus arvensis were tested for genotoxic and inhibitor activity on the total soluble protein content and the genomic template stability against corn Zea mays L. seed. The methanol extracts of leaf, stem and root of C. arvensis were diluted to 50, 75 and 100 μl concentrations and applied to corn seed. The total soluble protein and genomic template stability results were compared with the control. The results showed that especially 100 μl extracts of diluted leaf, stem and root had a strong inhibitory activity on the genomic template stability. The changes occurred in random amplification of polymorphic DNA (RAPD) profiles of C. arvensis extract treatment included variation in band intensity, loss of bands and appearance of new bands compared with control. Also, the results obtained from this study revealed that the increase in the concentrations of C. arvensis extract increased the total soluble protein content in maize. The results suggested that RAPD analysis and total protein analysis could be applied as a suitable biomarker assay for the detection of genotoxic effects of plant allelochemicals.

  11. The globally distributed genus Alexandrium: multifaceted roles in marine ecosystems and impacts on human health.

    Science.gov (United States)

    Anderson, Donald M; Alpermann, Tilman J; Cembella, Allan D; Collos, Yves; Masseret, Estelle; Montresor, Marina

    2012-02-01

    The dinoflagellate genus Alexandrium is one of the major harmful algal bloom (HAB) genera with respect to the diversity, magnitude and consequences of blooms. The ability of Alexandrium to colonize multiple habitats and to persist over large regions through time is testimony to the adaptability and resilience of this group of species. Three different families of toxins, as well as an as yet incompletely characterized suite of allelochemicals are produced among Alexandrium species. Nutritional strategies are equally diverse, including the ability to utilize a range of inorganic and organic nutrient sources, and feeding by ingestion of other organisms. Many Alexandrium species have complex life histories that include sexuality and often, but not always, cyst formation, which is characteristic of a meroplanktonic life strategy and offers considerable ecological advantages. Due to the public health and ecosystem impacts of Alexandrium blooms, the genus has been extensively studied, and there exists a broad knowledge base that ranges from taxonomy and phylogeny through genomics and toxin biosynthesis to bloom dynamics and modeling. Here we present a review of the genus Alexandrium, focusing on the major toxic and otherwise harmful species.

  12. Determination of the Efficiency of Some Essential Oil Compounds on the Development of Jonsongrass [(Sorghum halepense (L. Pers.

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    Ayşe YAZLIK

    2015-09-01

    Full Text Available Jonsongrass (Sorghum halepense (L. Pers. (SORHA is one of the most troublesome perennial weeds caused important yield reductions in the agricultural and environmental problems in the non-agricultural fields. Using a combination of several control strategies is required because Sorha cannot be effectively controlled by a single control method. One of the methods that can be used for the control of Sorha is the usage of allelopathic chemicals. The efficiency of the plants [oregano (Origanum vulgare L., lavender (Lavandula angustifolia L. and rosemary (Rosmarinus officinalis L.] that have allelochemicals on the SORHA were examined with this study. Using rosemary oil at the high rate (16 μl 38.465 cm2 gave the best results and reduced dry weight at 41.0% when it was applied as pre-emergence. The same essential oil rate obtained from rosemary was the highest adversely effects on the Sorha growth (48.0% when it was used as post-emergence. Post-emergence application of all three volatile oils has provided more influence on the Sorha growth compared to the pre-emergence application.

  13. Allelopathic Effects of Aqueous Extract of Leaf Stem and Root of Sorghum bicolor on Seed Germination and Seedling Growth of Vigna radiata L.

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    Amir MOOSAVI

    2011-05-01

    Full Text Available Seed germination under field conditions is highly influenced by the presence of other plants. Allelopathy is an important mechanism of plant competition, by producing phytotoxins to the plant environment in order to decline other plants growth. Soil sickness problem in farm lands is also known as an allelopathic effect or even autotoxicity. The toxicity of released allelochemicals by a plant in the environment is attributed to its function of concentration, age and metabolic stage. In this study we investigate the effect (5, 20, 35 and 50 g l-1 of leaf, stem and root water extract of sorghum on seed germination and seedling growth of mung bean. The results of the experiment showed that allelopathic effect of different concentrations was not significant for germination percentage, but germination rate and mean germination time decreased significantly by increasing the concentration of allelopathic extracts; also, there was a clear allelopathic effect of sorghum extract on seedling growth of mung bean. 50 g l-1 sorghum stem extract exhibited the highest inhibitory effect on root and shoot growth of mung bean. Among all parts of sorghum, stem extracts showed the highest allelopatic effect on seedling growth. Root extract showed higher inhibitory effect than leaf extracts.

  14. Coat of many colours—DNA reveals polymorphism of mantle patterns and colouration in Caribbean Cyphoma Röding, 1798 (Gastropoda, Ovulidae

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    Bastian T. Reijnen

    2017-03-01

    Full Text Available The iconic gastropod genus Cyphoma is commonly observed in the Caribbean, where it lives in association with various octocorallian hosts. Each species in the genus Cyphoma has a unique, characteristic mantle pattern and colouration, which separates the valid taxa. Because of its abundance and recognisability Cyphoma gibbosum has been used as a model organism in several studies concerning allelochemicals, reef degradation, and physical defence mechanisms. Molecular analyses based on four molecular markers (COI, 16S, H3 and 28S for three Cyphoma species (C. gibbosum, C. mcgintyi, C. signatum and an unidentified black morph, collected from three localities in the Caribbean, show that they represent morphological varieties of a single, genetically homogeneous species. This outcome is in agreement with previous anatomical studies. As a result C. mcgintyi and C. signatum are synonymised with C. gibbosum, which is a key result for future work using C. gibbosum as a model organism. The striking morphological differences in mantle pattern and colouration are hypothesised to be the result of one of three possible scenarios: rapid divergence, supergenes (including balanced polymorphism, or incipient speciation.

  15. Gas exchange, growth, and defense responses of invasive Alliaria petiolata (Brassicaceae) and native Geum vernum (Rosaceae) to elevated atmospheric CO2 and warm spring temperatures.

    Science.gov (United States)

    Anderson, Laurel J; Cipollini, Don

    2013-08-01

    Global increases in atmospheric CO2 and temperature may interact in complex ways to influence plant physiology and growth, particularly for species that grow in cool, early spring conditions in temperate forests. Plant species may also vary in their responses to environmental changes; fast-growing invasives may be more responsive to rising CO2 than natives and may increase production of allelopathic compounds under these conditions, altering species' competitive interactions. We examined growth and physiological responses of Alliaria petiolata, an allelopathic, invasive herb, and Geum vernum, a co-occurring native herb, to ambient and elevated spring temperatures and atmospheric CO2 conditions in a factorial growth chamber experiment. At 5 wk, leaves were larger at high temperature, and shoot biomass increased under elevated CO2 only at high temperature in both species. As temperatures gradually warmed to simulate seasonal progression, G. vernum became responsive to CO2 at both temperatures, whereas A. petiolata continued to respond to elevated CO2 only at high temperature. Elevated CO2 increased thickness and decreased nitrogen concentrations in leaves of both species. Alliaria petiolata showed photosynthetic downregulation at elevated CO2, whereas G. vernum photosynthesis increased at elevated temperature. Flavonoid and cyanide concentrations decreased significantly in A. petiolata leaves in the elevated CO2 and temperature treatment. Total glucosinolate concentrations and trypsin inhibitor activities did not vary among treatments. Future elevated spring temperatures and CO2 will interact to stimulate growth for A. petiolata and G. vernum, but there may be reduced allelochemical effects in A. petiolata.

  16. Integrating novel chemical weapons and evolutionarily increased competitive ability in success of a tropical invader.

    Science.gov (United States)

    Zheng, Yu-Long; Feng, Yu-Long; Zhang, Li-Kun; Callaway, Ragan M; Valiente-Banuet, Alfonso; Luo, Du-Qiang; Liao, Zhi-Yong; Lei, Yan-Bao; Barclay, Gregor F; Silva-Pereyra, Carlos

    2015-02-01

    The evolution of increased competitive ability (EICA) hypothesis and the novel weapons hypothesis (NWH) are two non-mutually exclusive mechanisms for exotic plant invasions, but few studies have simultaneously tested these hypotheses. Here we aimed to integrate them in the context of Chromolaena odorata invasion. We conducted two common garden experiments in order to test the EICA hypothesis, and two laboratory experiments in order to test the NWH. In common conditions, C. odorata plants from the nonnative range were better competitors but not larger than plants from the native range, either with or without the experimental manipulation of consumers. Chromolaena odorata plants from the nonnative range were more poorly defended against aboveground herbivores but better defended against soil-borne enemies. Chromolaena odorata plants from the nonnative range produced more odoratin (Eupatorium) (a unique compound of C. odorata with both allelopathic and defensive activities) and elicited stronger allelopathic effects on species native to China, the nonnative range of the invader, than on natives of Mexico, the native range of the invader. Our results suggest that invasive plants may evolve increased competitive ability after being introduced by increasing the production of novel allelochemicals, potentially in response to naïve competitors and new enemy regimes. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  17. Development of Novel Drugs from Marine Surface Associated Microorganisms

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    Suhelen Egan

    2010-03-01

    Full Text Available While the oceans cover more than 70% of the Earth’s surface, marine derived microbial natural products have been largely unexplored. The marine environment is a habitat for many unique microorganisms, which produce biologically active compounds (“bioactives” to adapt to particular environmental conditions. For example, marine surface associated microorganisms have proven to be a rich source for novel bioactives because of the necessity to evolve allelochemicals capable of protecting the producer from the fierce competition that exists between microorganisms on the surfaces of marine eukaryotes. Chemically driven interactions are also important for the establishment of cross-relationships between microbes and their eukaryotic hosts, in which organisms producing antimicrobial compounds (“antimicrobials”, may protect the host surface against over colonisation in return for a nutrient rich environment. As is the case for bioactive discovery in general, progress in the detection and characterization of marine microbial bioactives has been limited by a number of obstacles, such as unsuitable culture conditions, laborious purification processes, and a lack of de-replication. However many of these limitations are now being overcome due to improved microbial cultivation techniques, microbial (meta- genomic analysis and novel sensitive analytical tools for structural elucidation. Here we discuss how these technical advances, together with a better understanding of microbial and chemical ecology, will inevitably translate into an increase in the discovery and development of novel drugs from marine microbial sources in the future.

  18. Allelopathic interactions between the opportunistic species Ulva prolifera and the native macroalga Gracilaria lichvoides.

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    Dong Xu

    Full Text Available Allelopathy, one type of direct plant competition, can be a potent mechanism through which plant communities are structured. The aim of this study was to determine whether allelopathic interactions occur between the opportunistic green tide-forming species Ulva prolifera and the native macroalga Gracilaria lichvoides, both of which were collected from the coastline of East China sea. In laboratory experiments, the presence of G. lichvoides at 1.25 g wet weight L(-1 significantly inhibited growth and photosynthesis of U. prolifera at concentrations of 1.25, 2.50, and 3.75 g wet weight L(-1 (p0.05. Culture medium experiments further confirmed that some allelochemicals may be released by both of the tested macroalgae, and these could account for the observed physiological inhibition of growth and photosynthesis. Moreover, the native macroalgae G. lichvoides was a stronger competitor than the opportunistic species U. prolifera. Collectively, the results of the present study represent a significant advance in exploring ecological questions about the effects of green tide blooms on the macroalgal community.

  19. A Stable-Isotope Mass Spectrometry-Based Metabolic Footprinting Approach to Analyze Exudates from Phytoplankton

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    Mark R. Viant

    2013-10-01

    Full Text Available Phytoplankton exudates play an important role in pelagic ecology and biogeochemical cycles of elements. Exuded compounds fuel the microbial food web and often encompass bioactive secondary metabolites like sex pheromones, allelochemicals, antibiotics, or feeding attractants that mediate biological interactions. Despite this importance, little is known about the bioactive compounds present in phytoplankton exudates. We report a stable-isotope metabolic footprinting method to characterise exudates from aquatic autotrophs. Exudates from 13C-enriched alga were concentrated by solid phase extraction and analysed by high-resolution Fourier transform ion cyclotron resonance mass spectrometry. We used the harmful algal bloom forming dinoflagellate Alexandrium tamarense to prove the method. An algorithm was developed to automatically pinpoint just those metabolites with highly 13C-enriched isotope signatures, allowing us to discover algal exudates from the complex seawater background. The stable-isotope pattern (SIP of the detected metabolites then allowed for more accurate assignment to an empirical formula, a critical first step in their identification. This automated workflow provides an effective way to explore the chemical nature of the solutes exuded from phytoplankton cells and will facilitate the discovery of novel dissolved bioactive compounds.

  20. Bioassay standardization for the detection of allelopathic compounds and environmental toxicants using lettuce

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    Mateus Salomão Simões

    2013-09-01

    Full Text Available The purpose of this study was to assess different experimental conditions to determine a protocol for bioassays based on seed germination and early seedling growth using lettuce (Lactuca sativa L. cv. Grand Rapids as indicator species. This protocol aims to provide support for the standardization of assays of various chemicals such as allelochemicals and environmental toxicants. The following tests were performed: time of germination, temperature, light, solution volume and Petri dish size. For each test (except for time of germination, the influence of the conditions investigated was determined by the endpoints germination percentage, germination speed index, root length, seedling fresh weight and total dry weight. The results showed that variations in the methods altered the results. It is recommended that bioassays using L. sativa L. cv. Grand Rapids be carried out for a minimum period of four days for assessments of both germination and initial growth and that the experimental conditions include a temperature of 20°C, 90-mm Petri dishes or larger, 0.1 mL cypsela solution, and continuous light or 12-hour photoperiod.

  1. The Effect of Milk Thistle (Silybum marianum L. Extract on Growth and Enzyme Activities of Common Cocklebur (Xanthium strumarium L. Seedling

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    Shahla Faramarzi

    2017-08-01

    Full Text Available Introduction Allelopathy means any process involving the secondary metabolites (allelochemicals produced by plants, algae, bacteria, and fungi (excluding animals that influences the growth and development of agricultural and biological systems, with positive or negative effects. Plants produce secondary metabolites and in certain circumstances, these can act as phytotoxins, inhibiting or promoting some biochemical or physiological processes in the other plants or organisms. Toxicity of allelochemical compounds include effects on growth, chlorophyll content, photosynthesis, transpiration, stomatal conductance, relative growth rate, and oxygen uptake in many crops. Furthermore, the influence of allelochemicals on alpha amylase, oxidase, sucrose synthase activity and malon dialdehyde concentration were analysed. The role of numerous plant secondary metabolites is still unclear, and this raises curiosity for both plant physiologist and ecologists. Inhibitory effects on germination and establishments of crops caused by residues of either crops or weeds have lead to investigation of the release of toxic compounds from such residues. This present study was designed to evaluate the allelopathic potential of milk thistle for controlling common cocklebur in vegetables. Materials and Methods In order to investigate the effect of milk thistle aqueous extract on growth and enzyme activities of common cocklebur seedlings, two separate experiments were carried out in randomized complete design and randomized complete block designs with five and four replications, respectively, in spring 2012 in seed technology laboratory and greenhouse of Azad University, Shoushtar branch, Shoushtar, Iran. Milk thistle aqueous extract concentrations were involved (0, 5, 10 and 15% (v/v in petridish and (0, 10, 20 and 30% (v/v as spraying on common cocklebur seedlings under greenhouse conditions. Whole plants of milk thistle were gathered from medicine plant farm of Azad

  2. Chemical interactions between plants in Mediterranean vegetation: the influence of selected plant extracts on Aegilops geniculata metabolome.

    Science.gov (United States)

    Scognamiglio, Monica; Fiumano, Vittorio; D'Abrosca, Brigida; Esposito, Assunta; Choi, Young Hae; Verpoorte, Robert; Fiorentino, Antonio

    2014-10-01

    Allelopathy is the chemical mediated communication among plants. While on one hand there is growing interest in the field, on the other hand it is still debated as doubts exist at different levels. A number of compounds have been reported for their ability to influence plant growth, but the existence of this phenomenon in the field has rarely been demonstrated. Furthermore, only few studies have reported the uptake and the effects at molecular level of the allelochemicals. Allelopathy has been reported on some plants of Mediterranean vegetation and could contribute to structuring this ecosystem. Sixteen plants of Mediterranean vegetation have been selected and studied by an NMR-based metabolomics approach. The extracts of these donor plants have been characterized in terms of chemical composition and the effects on a selected receiving plant, Aegilops geniculata, have been studied both at the morphological and at the metabolic level. Most of the plant extracts employed in this study were found to have an activity, which could be correlated with the presence of flavonoids and hydroxycinnamate derivatives. These plant extracts affected the receiving plant in different ways, with different rates of growth inhibition at morphological level. The results of metabolomic analysis of treated plants suggested the induction of oxidative stress in all the receiving plants treated with active donor plant extracts, although differences were observed among the responses. Finally, the uptake and transport into receiving plant leaves of different metabolites present in the extracts added to the culture medium were observed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Seasonal and scale-dependent variability in nutrient- and allelopathy-mediated macrophyte–phytoplankton interactions

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    Lombardo P.

    2013-08-01

    Full Text Available macrophyte–phytoplankton interactions were investigated using a dual laboratory and field approach during a growing season, with responses quantified as changes in biomass. Short-term, close-range interactions in laboratory microcosms always led to mutual exclusion of macrophytes (Elodea canadensis or Ceratophyllum demersum and algae (Raphidocelis subcapitata, Fistulifera pelliculosa or cyanobacteria (Synechococcus leopoliensis, suggesting regulation by positive feedback mechanisms, progressively establishing and reinforcing a “stable state”. Laboratory results suggest that close-range regulation of R. subcapitata and F. pelliculosa by macrophytes was primarily via nutrient (N, P mediation. Sprig-produced allelochemicals may have contributed to inhibition of S. leopoliensis in C. demersum presence, while S. leopoliensis was apparently enhanced by nutrients leaked by subhealthy (discolored leaves; biomass loss E. canadensis. Seasonal changes in algal growth suppression were correlated with sprig growth. Marginal differences in in situ phytoplankton patterns inside and outside monospecific macrophyte stands suggest that the nutrient- and/or allelopathy-mediated close-range mechanisms observed in the laboratory did not propagate at the macrophyte-stand scale. Factors operating at a larger scale (e.g., lake trophic state, extent of submerged vegetation coverage appear to override in situ macrophyte–phytoplankton close-range interactions.

  4. Benzoxazinoids in root exudates of maize attract Pseudomonas putida to the rhizosphere.

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    Andrew L Neal

    Full Text Available Benzoxazinoids, such as 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H-one (DIMBOA, are secondary metabolites in grasses. In addition to their function in plant defence against pests and diseases above-ground, benzoxazinoids (BXs have also been implicated in defence below-ground, where they can exert allelochemical or antimicrobial activities. We have studied the impact of BXs on the interaction between maize and Pseudomonas putida KT2440, a competitive coloniser of the maize rhizosphere with plant-beneficial traits. Chromatographic analyses revealed that DIMBOA is the main BX compound in root exudates of maize. In vitro analysis of DIMBOA stability indicated that KT2440 tolerance of DIMBOA is based on metabolism-dependent breakdown of this BX compound. Transcriptome analysis of DIMBOA-exposed P. putida identified increased transcription of genes controlling benzoate catabolism and chemotaxis. Chemotaxis assays confirmed motility of P. putida towards DIMBOA. Moreover, colonisation essays in soil with Green Fluorescent Protein (GFP-expressing P. putida showed that DIMBOA-producing roots of wild-type maize attract significantly higher numbers of P. putida cells than roots of the DIMBOA-deficient bx1 mutant. Our results demonstrate a central role for DIMBOA as a below-ground semiochemical for recruitment of plant-beneficial rhizobacteria during the relatively young and vulnerable growth stages of maize.

  5. Effects of tannic acid on trypsin and leucine aminopeptidase activities in gypsy moth larval midgut

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    Mrdaković Marija

    2013-01-01

    Full Text Available The effects of allelochemical stress on genetic variations in the specific activities of gypsy moth digestive enzymes (trypsin and leucine aminopeptidase and relative midgut mass (indirect measure of food consumption, as well as variability in their plasticity, were investigated in fifth instar gypsy moths originating from two populations with different trophic adaptations (oak and locust-tree forests. Thirty-two full-sib families from the Quercus population and twenty-six full-sib families from the Robinia population were reared on an artificial diet with or without supplementation with tannic acid. Between population differences were observed as higher average specific activity of trypsin and relative midgut mass in larvae from the Robinia population. Significant broad-sense heritabilities were observed for the specific activity of trypsin in the control state, and for specific activity of leucine aminopeptidase in a stressful environment. Significantly lower heritability for relative midgut mass was recorded in larvae from the Robinia population reared under stressful conditions. Significant variability of trypsin plasticity in larvae from both populations and significant variability of leucine aminopeptidase plasticity in larvae from the Robinia population point to the potential for the evolution of enzyme adaptive plastic responses to the presence of stressor. Non-significant across-environment genetic correlations do not represent a constraint for the evolution of enzyme plasticity. [Projekat Ministarstva nauke Republike Srbije, br. 173027

  6. Allelopathic potential of Robinia pseudo-acacia L.

    Science.gov (United States)

    Nasir, Habib; Iqbal, Zahida; Hiradate, Syuntaro; Fujii, Yoshiharu

    2005-09-01

    Robinia pseudo-acacia L. (black locust) is a nonindigenous species currently invading the central part of Japanese grasslands. Several allelochemicals were identified and characterized from the leaf tissue. The growth of both radicle and hypocotyl in the tested species (barnyard grass, white clover, lettuce, and Chinese cabbage) was reduced when grown in soil mixed with the leaves of R. pseudo-acacia at various concentrations. Aqueous leaf extracts, when bioassayed, exhibited a significant suppression of radicle growth. Chromatographic separation of an ethanolic extract of R. pseudo-acacia leaves resulted in isolation of three compounds, identified as robinetin (1), myricetin (2), and quercetin (3) by nuclear magnetic resonance and mass spectroscopy. All inhibited root and shoot growth of lettuce. Robinetin, found in a large amount, caused 50% suppression of the root and shoot growth of lettuce at 100 ppm. The presence of these bioactive substances in leaf tissue suggests a potential role for flavonoids in R. pseudo-acacia invasion in introduced habitats.

  7. Volatiles and Nonvolatiles in Flourensia campestris Griseb. (Asteraceae), How Much Do Capitate Glandular Trichomes Matter?

    Science.gov (United States)

    Piazza, Leonardo A; López, Daniela; Silva, Mariana P; López Rivilli, Marisa J; Tourn, Mónica G; Cantero, Juan J; Scopel, Ana L

    2018-03-01

    The distribution and ultrastructure of capitate glandular trichomes (GTs) in Flourensia species (Asteraceae) have been recently elucidated, but their metabolic activity and potential biological function remain unexplored. Selective nonvolatile metabolites from isolated GTs were strikingly similar to those found on leaf surfaces. The phytotoxic allelochemical sesquiterpene (-)-hamanasic acid A ((-)-HAA) was the major constituent (ca. 40%) in GTs. Although GTs are quaternary ammonium compounds (QACs)-accumulating species, glycine betaine was not found in GTs; it was only present in the leaf mesophyll. Two (-)-HAA accompanying surface secreted products: compounds 4-hydroxyacetophenone (piceol; 1) and 2-hydroxy-5-methoxyacetophenone (2), which were isolated and fully characterized (GC/MS, NMR), were present in the volatiles found in GTs. The essential oils of fresh leaves revealed ca. 33% monoterpenes, 26% hydrocarbon- and 30% oxygenated sesquiterpenes, most of them related to cadinene and bisabolene derivatives. Present results suggest a main role of GTs in determining the volatile and nonvolatile composition of F. campestris leaves. Based on the known activities of the compounds identified, it can be suggested that GTs in F. campestris would play key ecological functions in plant-pathogen and plant-plant interactions. In addition, the strikingly high contribution of compounds derived from cadinene and bisabolene pathways, highlights the potential of this species as a source of high-valued bioproducts. © 2018 Wiley-VHCA AG, Zurich, Switzerland.

  8. Interaction of Pseudostellaria heterophylla with Fusarium oxysporum f.sp. heterophylla mediated by its root exudates in a consecutive monoculture system.

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    Zhao, Yongpo; Wu, Linkun; Chu, Leixia; Yang, Yanqiu; Li, Zhenfang; Azeem, Saadia; Zhang, Zhixing; Fang, Changxun; Lin, Wenxiong

    2015-02-03

    In this study, quantitative real-time PCR (qPCR) was used to determine the amount of Fusarium oxysporum, an important replant disease pathogen in Pseudostellaria heterophylla rhizospheric soil. Moreover, HPLC was used to identify phenolic acids in root exudates then it was further to explore the effects of the phenolic acid allelochemicals on the growth of F. oxysporum f.sp. heterophylla. The amount of F. oxysporum increased significantly in P. heterophylla rhizosphere soil under a consecutive replant system as monitored through qPCR analysis. Furthermore, the growth of F. oxysporum f.sp. heterophylla mycelium was enhanced by root exudates with a maximum increase of 23.8%. In addition, the number of spores increased to a maximum of 12.5-fold. Some phenolic acids promoted the growth of F. oxysporum f.sp. heterophylla mycelium and spore production. Our study revealed that phenolic acids in the root secretion of P. heterophylla increased long with its development, which was closely related to changes in rhizospheric microorganisms. The population of pathogenic microorganisms such as F. oxysporum in the rhizosphere soil of P. heterophylla also sharply increased. Our results on plant-microbe communication will help to better clarify the cause of problems associated with P. heterophylla under consecutive monoculture treatment.

  9. Activity of the Antioxidant Defense System in a Typical Bioinsecticide-and Synthetic Insecticide-treated Cowpea Storage Beetle F. (Coleoptera: Chrysomelidae

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    Ayodele O. Kolawole

    2014-01-01

    Full Text Available The non-enzymatic and enzymatic antioxidant defense systems play a major role in detoxification of pro-oxidant endobiotics and xenobiotics. The possible involvement of beetle non-enzymatic [α-tocopherol, glutathione (GSH, and ascorbic acid] and enzymatic [catalase (CAT, superoxide dismutase (SOD, peroxidase (POX, and polyphenol oxidase (PPO] antioxidant defense system on the insecticidal activity of synthetic insecticides (cypermethrin, 2,2-dicholorovinyl dimethyl phosphate, and λ-cyhalothrin and ethanolic plant extracts of Tithonia diversifolia, Cyperus rotundus, Hyptis suaveolens leaves , and Jatropha Curcas seeds was investigated. 2,2-Dicholorovinyl dimethyl phosphate (DDVP; 200 ppm, LC 50 = 13.24 ppm and T. diversifolia (20,000 ppm resulted in 100% beetle mortality at 96-hour post-treatment. The post-treatments significantly increased the beetle α-tocopherol and GSH contents. Activities of CAT, SOD, POX, and PPO were modulated by the synthetic insecticides and bioinsecticides to diminish the adverse effect of the chemical stresses. Quantitative and qualitative allelochemical compositions of bioinsecticides and chemical structure of synthetic insecticides possibly account and for modulation of their respective enzyme activities. Altogether, oxidative stress was enormous enough to cause maladaptation in insects. This study established that oxidative imbalance created could be the molecular basis of the efficacy of both insecticides and bio-insecticides. Two, there was development of functional but inadequate antioxidant defense mechanism in the beetle.

  10. Intraspecific and interspecific interactions mediated by a phytotoxin, (-)-catechin, secreted by the roots of Centaurea maculosa (spotted knapweed).

    Science.gov (United States)

    Weir, Tiffany L; Bais, Harsh Pal; Vivanco, Jorge M

    2003-11-01

    Centarea maculosa Lam. (spotted knapweed) is one of the most destructive invasive weeds in the western United States, particularly in pastures and rangelands. One of the components that may contribute to its invasiveness is the naturally produced, root-secreted allelochemical (-)-catechin. This compound has been shown to have broad-spectrum phytotoxic activity, possibly assisting C. maculosa in displacing native plant communities. As a recently characterized phytochemical, little is known about the specific effect of (-)-catechin on either C. maculosa or other plant species. We have found that, in vitro, C. maculosa begins to secrete phytotoxic levels of (-)-catechin within 2-3 weeks of seedling emergence. Furthermore, (-)-catechin concentrations consistent with those naturally secreted by C. maculosa were sufficient to inhibit germination in all species tested, including C. maculosa. These concentrations were also often either phytotoxic or growth inhibitory to seedlings in a range of plant species, while having no negative effects on the growth of C. maculosa seedlings. However, our results also indicate that different levels of resistance and susceptibility to (-)-catechin exist in plant populations, suggesting that the capability of C. maculosa to invade an area through allelochemistry may be dependent on the age and species composition of plants in that area.

  11. Impact of (±)-catechin on soil microbial communities

    Science.gov (United States)

    Kaur, Rajwant; Kaur, Surinder

    2009-01-01

    Catechin is a highly studied but controversial allelochemical reported as a component of the root exudates of Centaurea maculosa. Initial reports of high and consistent exudation rates and soil concentrations have been shown to be highly inaccurate, but the chemical has been found in root exudates at and much less frequently in soil but sporadically at high concentrations. Part of the problem of detection and measuring phytotoxicity in natural soils may be due to the confounding effect of soil microbes, and little is known about interactions between catechin and soil microbes. Here we tested the effect of catechin on soil microbial communities and the feedback of these effects to two plant species. We found that catechin inhibits microbial activity in the soil we tested, and by doing so appears to promote plant growth in the microbe-free environment. This is in striking contrast to other in vitro studies, emphasizing the highly conditional effects of the chemical and suggesting that the phytotoxic effects of catechin may be exerted through the microbes in some soils. PMID:19704908

  12. Metabolomics in chemical ecology.

    Science.gov (United States)

    Kuhlisch, Constanze; Pohnert, Georg

    2015-07-01

    Chemical ecology elucidates the nature and role of natural products as mediators of organismal interactions. The emerging techniques that can be summarized under the concept of metabolomics provide new opportunities to study such environmentally relevant signaling molecules. Especially comparative tools in metabolomics enable the identification of compounds that are regulated during interaction situations and that might play a role as e.g. pheromones, allelochemicals or in induced and activated defenses. This approach helps overcoming limitations of traditional bioassay-guided structure elucidation approaches. But the power of metabolomics is not limited to the comparison of metabolic profiles of interacting partners. Especially the link to other -omics techniques helps to unravel not only the compounds in question but the entire biosynthetic and genetic re-wiring, required for an ecological response. This review comprehensively highlights successful applications of metabolomics in chemical ecology and discusses existing limitations of these novel techniques. It focuses on recent developments in comparative metabolomics and discusses the use of metabolomics in the systems biology of organismal interactions. It also outlines the potential of large metabolomics initiatives for model organisms in the field of chemical ecology.

  13. Molecular cloning of allelopathy related genes and their relation to HHO in Eupatorium adenophorum.

    Science.gov (United States)

    Guo, Huiming; Pei, Xixiang; Wan, Fanghao; Cheng, Hongmei

    2011-10-01

    In this study, conserved sequence regions of HMGR, DXR, and CHS (encoding 3-hydroxy-3-methylglutaryl-CoA reductase, 1-deoxyxylulose-5-phosphate reductoisomerase and chalcone synthase, respectively) were amplified by reverse transcriptase (RT)-PCR from Eupatorium adenophorum. Quantitative real-time PCR showed that the expression of CHS was related to the level of HHO, an allelochemical isolated from E. adenophorum. Semi-quantitative RT-PCR showed that there was no significant difference in expression of genes among three different tissues, except for CHS. Southern blotting indicated that at least three CHS genes are present in the E. adenophorum genome. A full-length cDNA from CHS genes (named EaCHS1, GenBank ID: FJ913888) was cloned. The 1,455 bp cDNA contained an open reading frame (1,206 bp) encoding a protein of 401 amino acids. Preliminary bioinformatics analysis of EaCHS1 revealed that EaCHS1 was a member of CHS family, the subcellular localization predicted that EaCHS1 was a cytoplasmic protein. To the best of our knowledge, this is the first report of conserved sequences of these genes and of a full-length EaCHS1 gene in E. adenophorum. The results indicated that CHS gene is related to allelopathy of E. adenophorum.

  14. Phytotoxic effects and chemical analysis of leaf extracts from three Phytolaccaceae species in South Korea.

    Science.gov (United States)

    Kim, Yong Ok; Johnson, Jon D; Lee, Eun Ju

    2005-05-01

    We analyzed phenolic compounds and other elements in leaf extracts and compared morphology of three species of the Phytolaccaceae family found in South Korea. To test allelochemical effects of the three Phytolacca species, we also examined seed germination and dry weight of seedlings of Lactuca indica and Sonchus oleraceus treated with leaf extracts. The concentrations of total phenolic compounds were exotic Phytolacca esculenta (3.9 mg/l), native Phytolacca insularis (4.4 mg/l), and exotic Phytolacca americana (10.2 mg/l). There was no significant difference in concentrations between P. esculenta and P. insularis, but the concentration of total phenolics in P. americana was two times higher than either P. esculenta or P. insularis. Analysis of aqueous extracts by HPLC showed seven phenolic compounds (gallic acid, protocatechuic acid, chlorogenic acid, caffeic acid, m-hydroxybenzoic acid, p-coumaric acid, and cinnamic acid). Total phenolics in P. americana were eight to 16 times higher than either P. esculenta or P. insularis, respectively. P. americana inhibited seed germination and dry weight of the two assay species. The phytotoxic effects of the two Phytolacca species were different, despite the fact that P. esculenta and P. insularis had similar levels of total phenolic compounds. We also found that P. americana had invaded Ullung Island, which suggested that P. americana had excellent adaptability to the environment. The three species of Phytolaccaceae in South Korea can be distinguished by their different allelopathic potentials and morphologies.

  15. Chemical composition of Clinopodium menthifolium aqueous extract and its influence on antioxidant system in black nightshade (Solanum nigrum and pepper (Capsicum annuum seedlings and mortality rate of whitefly (Trialeurodes vaporariorum adults

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    J. Šućur

    2017-11-01

    Full Text Available The use of allelochemicals as weed control agents is becoming widely investigated. However, the impact of these bioherbicides on cultivated plants is less known. This study was carried out in order to evaluate the allelopathic effects of the aqueous extract of Clinopodium menthifolium on black nightshade (Solanum nigrum antioxidant properties to explore the potential of this species in weed control and on pepper (Capsicum annuum antioxidant properties so as to assess its possible side effects when applied as bioherbicide in organic production. Taking into account that plant extracts should be an alternative source for insect control, additional aim was also to evaluate contact effect of C. menthifolium aqueous extract against the greenhouse whitefly (Trialeurodes vaporariorum. Analysis by HPLC confirmed the presence of gallic acid, caffeic acid and 2-hidroxy-cinnamic acid as major components in the C. menthifolium aqueous extract. Both tested concentrations of C. menthifolium aqueous extract induced lipid peroxidation in black nightshade leaves and roots. It was observed that the aqueous extract with a concentration of 0.1% showed a toxic effect with 50% mortality of greenhouse whitefly adults.

  16. Allelopathic Effects of Aqueous Extract of Leaf Stem and Root of Sorghum bicolor on Seed Germination and Seedling Growth of Vigna radiata L.

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    Amir MOOSAVI

    2011-05-01

    Full Text Available Seed germination under field conditions is highly influenced by the presence of other plants. Allelopathy is an important mechanism of plant competition, by producing phytotoxins to the plant environment in order to decline other plants� growth. Soil sickness problem in farm lands is also known as an allelopathic effect or even autotoxicity. The toxicity of released allelochemicals by a plant in the environment is attributed to its function of concentration, age and metabolic stage. In this study we investigate the effect (5, 20, 35 and 50 g l-1 of leaf, stem and root water extract of sorghum on seed germination and seedling growth of mung bean. The results of the experiment showed that allelopathic effect of different concentrations was not significant for germination percentage, but germination rate and mean germination time decreased significantly by increasing the concentration of allelopathic extracts; also, there was a clear allelopathic effect of sorghum extract on seedling growth of mung bean. 50 g l-1 sorghum stem extract exhibited the highest inhibitory effect on root and shoot growth of mung bean. Among all parts of sorghum, stem extracts showed the highest allelopatic effect on seedling growth. Root extract showed higher inhibitory effect than leaf extracts.

  17. Phytotoxicity of leaf aqueous extract of Rapanea umbellata (Mart. Mez (Primulaceae on weeds - doi: 10.4025/actasciagron.v35i2.16166

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    Paula Novaes

    2012-12-01

    Full Text Available Allelopathic substances can be used to develop weed control alternatives based on natural products. The objective of this study was to compare the phytotoxic activity of aqueous leaf extracts of Rapanea umbellata with the toxicity of a synthetic herbicide on the germination and growth of weed species. The weeds species barnyard grass (Echinochloa crus-galli, wild poinsettia (Euphorbia heterophylla and morning glory (Ipomoea grandifolia were used. The effects of the aqueous leaf extract of R. umbellata at concentrations of 10% and 5% (g mL-1 were compared to the control (distilled water and to the synthetic herbicide oxyfluorfen. The average weed germination time was significantly lower (p < 0.05 in control than in extract and herbicide treatments. The herbicide had more significant effects than the extract on the initial growth of the aerial part. However, the initial growth of the root part was significantly more affected by the leaf extract than by the herbicide. The extract also caused many disorders in weed root anatomy. Therefore, the leaf aqueous extract of R. umbellata showed important results that indicate that it should be bioprospected and that its allelochemicals should be purified for the discovery of natural-origin herbicides.

  18. Reduced herbicide doses in combination with allelopathic plant extracts suppress weeds in wheat

    International Nuclear Information System (INIS)

    Afridi, R.A.; Khan, M.A.

    2014-01-01

    Allelopathy is gaining popularity worldwide probably for decreasing the cost of production and environment friendly weed suppressing approach. Repeated field studies conducted during 2011-12 and 2012-13 at Agricutural Research Institute Tarnab, Peshawar, Pakistan where allelopathic water extracts of Oryza sativa, Parthenium hysterophorus, Phragmites australis and Datura alba along with reduced doses of phenoxaprop-p-ethyl and bromoxinil+MCPA were tested for controlling weeds in wheat. It was observed that weed density was encouragly suppressed whereas spike length (cm), number of spikelets spike-1 and 1000 grain weight (g) of the wheat were improved when the allelopathic plant water extracts were used in combination with lower doses of herbicides. Thus, allelochemicals provide weed suppressing option in wheat. However, more studies are required to fully explore the possibility of weed management and isolation of the chemicals involved in weed suppression for environment friendly weed management in wheat. Such studies may decrease the cost of crop production and total use of herbicides. (author)

  19. Flavonoids from leaves of Derris urucu: assessment of potential effects on seed germination and development of weeds

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    EWERTON A.S. DA SILVA

    2013-09-01

    Full Text Available In some previous studies, we described the isolation of nine compounds from leaves of Derris urucu, a species found widely in the Amazon rainforest, identified as five stilbenes and four dihydroflavonols. In this work, three of these dihydroflavonols [urucuol A (1, urucuol B (2 and isotirumalin (3] were evaluated to identify their potential as allelochemicals, and we are also reporting the isolation and structural determination of a new flavonoid [5,3′-dihydroxy-4′-methoxy-(7,6:5″,6″-2″,2″-dimethylpyranoflavanone (4]. We investigated the effects of the dihydroflavonols 1-3 on seed germination and radicle and hypocotyl growth of the weed Mimosa pudica, using solutions at 150 mg.L–1. Urucuol B, alone, was the substance with the greatest potential to inhibit seed germination (26%, while isotirumalin showed greater ability to reduce the development of the hypocotyl (25%, but none of the three substances showed the potential to inhibit radicle. When combined in pairs, the substances showed synergism for the development of root and hypocotyl and effects on seed germination that could be attributed to antagonism. When tested separately, the trend has become more intense effects on seed germination, while for the substances tested in pairs, the intensity of the effect was greater on development of weed.

  20. Allelopathic effects of Clinopodium menthifolium and Salvia sclarea aqueous extracts

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    Šućur Jovana T.

    2016-01-01

    Full Text Available Secondary plant biomolecules are the main agents in biochemical inter­actions between plants and the environment. It is possible to distinguish the role of secondary biomolecules in allelopathic (plant-plant activity, plant-insect, plant-microbe, plant-herbivore and others. These interactions can significantly affect the productivity of agricultural crops. Application of allelochemicals into agricultural practice may reduce the use of herbicides. Effect of Salvia sclarea L. and Clinopodium menthifolium (Host aqueous extracts on lipid peroxidation process, as well as the activity of antioxidant enzymes in leaves and roots of Jimson weed (Datura stramonium L. and soybean (Glycine max L. seedlings were examined 24 h, 72 h and 120 h after the treatment. The third aim was to evaluate effectiveness of aqueous extract as contact toxicant against Rhyzopertha dominica. Our results showed that S. sclarea aqueous extract induced lipid peroxidation in roots of Jimson weed seedlings 24 h after the treatment. Furthermore, both tested concentrations of C. menthifolium aqueous extract induced lipid peroxidation in Jimson weed roots 72 h and 120 h after the treatment. It was observed that S. sclarea aqueous extract showed toxic effect against R. dominica, with high mortality rate (above 95%.

  1. Impact of (+/-)-catechin on soil microbial communities.

    Science.gov (United States)

    Inderjit; Kaur, Rajwant; Kaur, Surinder; Callaway, Ragan M

    2009-01-01

    Catechin is a highly studied but controversial allelochemical reported as a component of the root exudates of Centaurea maculosa. Initial reports of high and consistent exudation rates and soil concentrations have been shown to be highly inaccurate, but the chemical has been found in root exudates at and much less frequently in soil but sporadically at high concentrations. Part of the problem of detection and measuring phytotoxicity in natural soils may be due to the confounding effect of soil microbes, and little is known about interactions between catechin and soil microbes. Here we tested the effect of catechin on soil microbial communities and the feedback of these effects to two plant species. We found that catechin inhibits microbial activity in the soil we tested, and by doing so appears to promote plant growth in the microbe-free environment. This is in striking contrast to other in vitro studies, emphasizing the highly conditional effects of the chemical and suggesting that the phytotoxic effects of catechin may be exerted through the microbes in some soils.

  2. Allelopathic research in Brazil

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    Manuel Reigosa

    2013-12-01

    Full Text Available In this article, we review allelopathy studies conducted in Brazil or involving plant species that occur in the country. Conceptions and misconceptions associated with allelopathy, as well as some international criteria to be applied in allelopathic research, are presented and discussed. We observed a sharp increase in the number of papers on this subject conducted in Brazil between 1991 and 2010. However, most studies are conducted under laboratory conditions, lack a clear hypothesis or a solid justification, and typically make use of target species that do not co-exist with the donor species under natural conditions. We also found that most studies do not take the additional steps in order to purify and identify the bioactive molecules. We recommend that further studies be conducted in order to explore the potential of plant biodiversity in Brazil. Such studies could lead to the development of new molecular structures (allelochemicals that could be used in the control of pests and weeds, thereby reducing the use of the harmful synthetic herbicides that are currently being widely employed.

  3. Allelopathic Activity and Chemical Composition of Rhynchosia minima (L.) DC. Essential Oil from Egypt.

    Science.gov (United States)

    Abd El-Gawad, Ahmed M; El-Amier, Yasser A; Bonanomi, Giuliano

    2018-01-01

    Aromatic plants attract the attention of many researchers worldwide due to their worthy applications in agriculture, human prosperity, and the environment. Essential oil (EO) could be exploited as effective alternatives to synthetic compounds as it has several biological activities including allelopathy. The EO from the aerial parts of Rhynchosia minima was extracted by hydrodistillation and investigated by gas chromatography/mass spectrometry (GC/MS). Different concentrations (50, 100, 150 and 200 μL L -1 ) of the EO were prepared for investigation of their allelopathic potential on two weeds; Dactyloctenium aegyptium and Rumex dentatus. Twenty-eight compounds, mainly sesquiterpenes (69.13%) were determined. The major compounds are α-eudesmol, 2-allyl-5-tert-butylhydroquinone, caryophyllene oxide, trans-caryophyllene, and τ-cadinol. The EO from the R. minima showed a significant inhibition of D. aegyptium and R. dentatus germination, while the seedling growth was stimulated. Therefore, it is not recommended to treat these noxious weeds with the EO of R. minima before the germination. In contrast, the apparent stimulatory effect on the seedling growth offers further studies to use the EO of R. minima to enhance the fitness of different economic crops. However, characterization of green bio-herbicides such as EO (allelochemicals) from wild plants raises a new opportunity for the incorporation of new technology of bio-control against the noxious weeds. © 2018 Wiley-VHCA AG, Zurich, Switzerland.

  4. Competition between a nonallelopathic phytoplankton and an allelopathic phytoplankton species under predation.

    Science.gov (United States)

    Kengwoung-Keumo, Jean-Jacques

    2016-08-01

    We propose a model of two-species competition in the chemostat for a single growth-limiting, nonreproducing resource that extends that of Roy [38]. The response functions are specified to be Michaelis-Menten, and there is no predation in Roy's work. Our model generalizes Roy's model to general uptake functions. The competition is exploitative so that species compete by decreasing the common pool of resources. The model also allows allelopathic effects of one toxin-producing species, both on itself (autotoxicity) and on its nontoxic competitor (phytotoxicity). We show that a stable coexistence equilibrium exists as long as (a) there are allelopathic effects and (b) the input nutrient concentration is above a critical value. The model is reconsidered under instantaneous nutrient recycling. We further extend this work to include a zooplankton species as a fourth interacting component to study the impact of predation on the ecosystem. The zooplankton species is allowed to feed only on the two phytoplankton species which are its perfectly substitutable resources. Each of the models is analyzed for boundedness, equilibria, stability, and uniform persistence (or permanence). Each model structure fits very well with some harmful algal bloom observations where the phytoplankton assemblage can be envisioned in two compartments, toxin producing and non-toxic. The Prymnesium parvum literature, where the suppressing effects of allelochemicals are quite pronounced, is a classic example. This work advances knowledge in an area of research becoming ever more important, which is understanding the functioning of allelopathy in food webs.

  5. Effects of different nitrogen levels on phytotoxicity of some allelopathic crops

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    Y. NOROUZI

    2016-04-01

    Full Text Available Intensive usage of herbicides can result in the serious negative impacts on environment. Allelopathy by reducing seed germination and early seedling growth can play a fundamental role in suppressing weeds in crop fields. The effectiveness of allelochemicals is governed by different factors such as soil nutrient status, pH and microorganisms. Outdoor pot experiments were conducted at the Faculty of Agriculture and Natural Resources of Razi University, Kermanshah, Iran, in 2013, to evaluate the effects of different levels of N fertilizer (0, 150, 300 kg ha-1 on the suppressing effects of alfalfa (Medicago sativa L., sorghum (Sorghum bicolor L., and tobacco (Nicotiana tabacum L. plant materials on emergence and growth parameters of some weed species including Johnson grass (Sorghum halepense (L. Pers., barnyard grass (Echinochloa crus-galli (L. Beauv. and redroot pigweed (Amaranthus retroflexus L.. Results indicated that adding plant materials of tobacco, sorghum, and alfalfa substantially reduced seed germination and early growth of the tested weeds. However, the weed species responded differently to the presence of the allelopathic plant materials. The use of N fertilizer had significant effects on the inhibitory potentials of the allelopathic plants. However, we didn't find consistent trends regarding the responses of the allelopathic crops to elevated N fertilizer levels in related to the traits under study.

  6. The Effect of Polyunsaturated Aldehydes on Skeletonema marinoi (Bacillariophyceae: The Involvement of Reactive Oxygen Species and Nitric Oxide

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    Alessandra A. Gallina

    2014-07-01

    Full Text Available Nitric oxide (NO and reactive oxygen species (ROS production was investigated in the marine diatom, Skeletonema marinoi (SM, exposed to 2E,4E/Z-decadienal (DECA, 2E,4E/Z-octadienal (OCTA, 2E,4E/Z-heptadienal (HEPTA and a mix of these last two (MIX. When exposed to polyunsaturated aldehydes (PUA, a decrease of NO was observed, proportional to the PUA concentration (85% of the initial level after 180 min with 66 µM DECA. Only OCTA, HEPTA and MIX induced a parallel increase of ROS, the highest (2.9-times the control with OCTA concentrations twice the EC50 for growth at 24 h (20 μM. The synthesis of carotenoids belonging to the xanthophyll cycle (XC was enhanced during exposure, suggesting their antioxidant activity. Our data provide evidence that specific pathways exist as a reaction to PUA and that they depend upon the PUA used and/or the diatom species. In fact, Phaeodactylum tricornutum (PT produces NO in response to DECA, but not to OCTA. We advance the hypothesis that SM perceives OCTA and HEPTA as intra-population infochemicals (as it produces PUA, while PT (non-PUA producing species perceives them as allelochemicals. The ability to produce and to use PUA as infochemicals may underlie ecological traits of different diatom species and modulate ecological success in natural communities.

  7. Coevolution between invasive and native plants driven by chemical competition and soil biota.

    Science.gov (United States)

    Lankau, Richard A

    2012-07-10

    Although reciprocal evolutionary responses between interacting species are a driving force behind the diversity of life, pairwise coevolution between plant competitors has received less attention than other species interactions and has been considered relatively less important in explaining ecological patterns. However, the success of species transported across biogeographic boundaries suggests a stronger role for evolutionary relationships in shaping plant interactions. Alliaria petiolata is a Eurasian species that has invaded North American forest understories, where it competes with native understory species in part by producing compounds that directly and indirectly slow the growth of competing species. Here I show that populations of A. petiolata from areas with a greater density of interspecific competitors invest more in a toxic allelochemical under common conditions. Furthermore, populations of a native competitor from areas with highly toxic invaders are more tolerant to competition from the invader, suggesting coevolutionary dynamics between the species. Field reciprocal transplants confirmed that native populations more tolerant to the invader had higher fitness when the invader was common, but these traits came at a cost when the invader was rare. Exotic species are often detrimentally dominant in their new range due to their evolutionary novelty; however, the development of new coevolutionary relationships may act to integrate exotic species into native communities.

  8. In vitro cytotoxicity of allelopathic plants Adonis vernalis L. Origanum vulgare ssp. vulgare L. and Nepeta nuda subsp. nuda

    Science.gov (United States)

    Koleva, Vanya; Dragoeva, Asya; Stoyanova, Zheni; Yordanova, Zhenia; Ali, Selime; Uzunov, Nikolay M.; Melendez-Alafort, Laura; Rosato, Antonio; Enchev, Dobromir D.

    2018-03-01

    Medicinal plants produce various secondary metabolites as a part of their chemical defence and survival in nature. These compounds have a wide range of biological activities. Nowadays, medicinal plants are used as source of allelochemicals and new effective anticancer agents. Our previous studies revealed allelopathic potential of water extracts of Adonis vernalis L. (Ranunculaceae), Origanum vulgare ssp. vulgare L. and Nepeta nuda subsp. nuda (Lamiaceae). Present study aimed to evaluate the effect of the same extracts in vitro on human hepatoma cell line SK-HEP-1. Cell proliferation/viability was assessed using Premixed WST-1 Cell Proliferation Reagent. Adonis water extract (1.83mg/ml) had notable negative influence on cancer cell line tested. Oregano (3.5 mg/ml) also exerted negative effect, but to a lesser degree. On the contrary, nepeta water extract (6.59 mg/ml) had an opposite effect, stimulating cell proliferation. One possible explanation could be the type of extraction: after treatment with nepeta methanol extract (6.59 mg/ml) cell viability was significantly reduced. In conclusion, Adonis vernalis and Nepeta nuda subsp. nuda possess metabolites with growth inhibitory effect on human hepatoma cell line SK-HEP-1. Further research is needed to clarify biological activity of lower concentrations which are appropriate to enable the design of new anticancer drugs.

  9. Evaluation of the Impact of Weed Control Methods on Quantitative and Qualitative Characteristics of Moldavian Balm; A Medicinal Plant

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    Janmohammadi Mohsen

    2016-12-01

    Full Text Available Moldavian balm is an annual herbaceous plant and its lemon-scented leaves contain essential oil. However, weeds adversely affect its growth by release of allelochemicals, and/or direct competition for nutrient, moisture, light and space. Current experiment was conducted to evaluate the different weed control methods including preventive approach (soil pasteurization, mechanical methods (one hand weeding, two hand weeding, and successive hand weeding for weed free condition, and chemical control by synthetic herbicides (haloxyfop-R-methyl and trifluralin. Results revealed that stem diameter, quantity of secondary branches, flower-bearing branches and leaves were significantly affected by weed control treatments; the highest lateral growth was obtained by successive mechanical weed control and two hand weeding method, respectively. This trend was also observed in canopy spread and chlorophyll content. Pre-emergence control by trifluralin considerably accelerated the initiation of flowering in Moldavian balm. However, observation of qualitative traits showed that the highest essential oil content and oil yield was obtained when the plants grew in weed free soil which was pasteurized. Considering the recognized essential oils, the most responsive composition was including Geranial, Geranyl acetate, Neral and Geraniol. The lowest amount of Neral was recorded in postemergence control performed by means of haloxyfop-R-methyl herbicide.

  10. Allelopathic Stress Produced by Bitter Gourd (Momordica charantia L.

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    N.B. Singh

    2014-05-01

    Full Text Available The present study deals with in vitro effects of allelochemicals present in leaf and fruit leachate of Momordica charantia in vitro on plant growth and metabolism of Lycopersicon esculentum. Momordica was selected as a donor plant and tomato as recipient. Seeds of tomato were shown in pots and after germination different concentrations viz. 25, 50, 75 and 100% of leaf and fruit leachates were applied as treatment. Twenty days old seedlings were harvested for biophysical and biochemical analyses. The root and shoot length, fresh and dry weight of the seedlings decreased in dose dependent manner. The reduction in pigment and protein contents and nitrate reductase activity was concentration dependent. Membrane leakage increased as the concentration of leachates increased. Activities of antioxidant enzymes viz. superoxide dismutase (SOD, catalase (CAT and peroxidase (POX activities significantly enhanced under allelopathic stress. Inhibition of various metabolic activities under allelopathic stress resulted in decreased plant growth and development. The fruit leachate of Momordica was more inhibitory than leaf leachate.

  11. Microbial brokers of insect-plant interactions revisited.

    Science.gov (United States)

    Douglas, Angela E

    2013-07-01

    Recent advances in sequencing methods have transformed the field of microbial ecology, making it possible to determine the composition and functional capabilities of uncultured microorganisms. These technologies have been instrumental in the recognition that resident microorganisms can have profound effects on the phenotype and fitness of their animal hosts by modulating the animal signaling networks that regulate growth, development, behavior, etc. Against this backdrop, this review assesses the impact of microorganisms on insect-plant interactions, in the context of the hypothesis that microorganisms are biochemical brokers of plant utilization by insects. There is now overwhelming evidence for a microbial role in insect utilization of certain plant diets with an extremely low or unbalanced nutrient content. Specifically, microorganisms enable insect utilization of plant sap by synthesizing essential amino acids. They also can broker insect utilization of plant products of extremely high lignocellulose content, by enzymatic breakdown of complex plant polysaccharides, nitrogen fixation, and sterol synthesis. However, the experimental evidence for microbial-mediated detoxification of plant allelochemicals is limited. The significance of microorganisms as brokers of plant utilization by insects is predicted to vary, possibly widely, as a result of potentially complex interactions between the composition of the microbiota and the diet and insect developmental age or genotype. For every insect species feeding on plant material, the role of resident microbiota as biochemical brokers of plant utilization is a testable hypothesis.

  12. Fish Welfare in Aquaponic Systems: Its Relation to Water Quality with an Emphasis on Feed and Faeces—A Review

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    Hijran Yavuzcan Yildiz

    2017-01-01

    Full Text Available Aquaponics is the combination of aquaculture (fish and hydroponic cultivation of plants. This review examines fish welfare in relation to rearing water quality, fish feed and fish waste and faeces to develop a sustainable aquaponic system where the co-cultured organisms, fish, bacteria in biofilters and plants, should be considered holistically in all aquaponics operations. Water quality parameters are the primary environmental consideration for optimizing aquaponic production and for directly impacting fish welfare/health issues and plant needs. In aquaponic systems, the uptake of nutrients should be maximised for the healthy production of the plant biomass but without neglecting the best welfare conditions for the fish in terms of water quality. Measures to reduce the risks of the introduction or spread of diseases or infection and to increase biosecurity in aquaponics are also important. In addition, the possible impacts of allelochemicals, i.e., chemicals released by the plants, should be taken into account. Moreover, the effect of diet digestibility, faeces particle size and settling ratio on water quality should be carefully considered. As available information is very limited, research should be undertaken to better elucidate the relationship between appropriate levels of minerals needed by plants, and fish metabolism, health and welfare. It remains to be investigated whether and to what extent the concentrations of suspended solids that can be found in aquaponic systems can compromise the health of fish. Water quality, which directly affects fish health and well-being, is the key factor to be considered in all aquaponic systems.

  13. Influence of waterborne gallic and pelargonic acid exposures on biochemical and reproductive parameters in the zebrafish (Danio rerio).

    Science.gov (United States)

    Techer, Didier; Milla, Sylvain; Fontaine, Pascal; Viot, Sandrine; Thomas, Marielle

    2017-01-01

    Gallic and pelargonic acids are biologically derived substances receiving a growing interest as eco-friendly biocides with potential applications in freshwater system management. However, some data gaps remain to address their chronic ecotoxicity issue, particularly for fish. This work aimed at investigating the sublethal effects of a long-term waterborne exposure of zebrafish to these compounds. Mature fish were exposed to gallic or pelargonic acid at the concentrations of 0, 0.05, 0.5 and 5 mg/L during one month under semi-static conditions. Fecundity, hatching rate and median hatching time were regularly evaluated. Circulating sex hormone levels (11 ketotestosterone -11 KT, 17 βestradiol -E2-), plasma vitellogenin (Vtg), and gonad histology were monitored in males and females after exposure. Lactate dehydrogenase (LDH), total glutathione peroxydase (GPx) and glutathione-S transferase (GST) activities were assessed as enzymatic biomarkers of exposure in fish liver. Significant increases of GPx activity were reported in females exposed to both type of chemicals regardless the contamination level. Moreover, 5 mg/L gallic acid induced a decrease in 11-KT levels for males. For fish exposed to pelargonic acid, decreases in circulating hormone levels were reported respectively at 0.05 and 5 mg/L for 11-KT in males, and at 0.5 mg/L for E2 in females. However, no histological alteration in gonads neither significant variation in reproductive performances were detected following zebrafish exposure to gallic or pelargonic acid. Additional investigations concerning the mode of application and the environmental fate of these substances may warrant their further use in freshwater systems at concentrations compatible with biocidal/allelochemical effects. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 227-240, 2017. © 2015 Wiley Periodicals, Inc.

  14. Nuclear receptors HR96 and ultraspiracle from the fall armyworm (Spodoptera frugiperda), developmental expression and induction by xenobiotics.

    Science.gov (United States)

    Giraudo, Maeva; Audant, Pascaline; Feyereisen, René; Le Goff, Gaëlle

    2013-05-01

    The fall armyworm Spodoptera frugiperda is a major polyphagous pest in agriculture and little is known on how this insect can adapt to the diverse and potentially toxic plant allelochemicals that they ingest or to insecticides. To investigate the involvement of nuclear receptors in the response of S. frugiperda to its chemical environment, we cloned SfHR96, a nuclear receptor orthologous to the mammalian xenobiotic receptors, pregnane X receptor (PXR) and constitutive androstane receptor (CAR). We also cloned ultraspiracle (USP), the ortholog of retinoid X receptor (RXR) that serves as partner of dimerization of PXR and CAR. Cloning of SfUSP revealed the presence of two isoforms, SfUSP-1 and SfUSP-2 in this species, that differ in their N-terminal region. The expression of these receptors as well as the ecdysone receptor was studied during specific steps of development in different tissues. SfHR96 was constitutively expressed in larval midgut, fat body and Malpighian tubules throughout the last two instars and pupal stage, as well as in Sf9 cells. EcR and SfUSP-2 showed peaks of expression before larval moults and during metamorphosis, whereas SfUSP-1 was mainly expressed in the pre-pupal stage. Receptor induction was followed after exposure of larvae or cells to 11 chemical compounds. SfHR96 was not inducible by the tested compounds. EcR was significantly induced by the 20-hydroxyecdysone agonist, methoxyfenozide, and SfUSP showed an increase expression when exposed to the juvenile hormone analog, methoprene. The cloning of these nuclear receptors is a first step in understanding the important capacities of adaptation of this insect pest. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Chemical composition and antifungal activity of Trigonella foenum-graecum L. varied with plant ploidy level and developmental stage

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    Faten Omezzine

    2017-05-01

    Full Text Available The efficacy of aerial parts’ organic extracts of diploid and mixoploid Trigonella foenum-graecum L. plants, harvested at three developmental stages (vegetative, flowering and fruiting was evaluated for their antifungal activity against Fusarium oxysporum f. sp. radicis-lycopersici (FORL and F. oxysporum f. sp. lycopersici (FOL. All tested extracts inhibited FORL and FOL mycelial growth. The organic extracts of diploid plants were found to be less toxic than mixoploid ones and this toxicity varied with the plant developmental stages. The diploids were most toxic, for the two strains, at the fruiting stage; however, mixoploids were more toxic at the vegetative stage for FOL and at flowering one for FORL. FOL was found to be more sensitive to fenugreek extracts when compared to FORL. LC–MS/MS analysis of methanolic extract of fenugreek aerial parts showed eleven different flavonol glycosides (quercetin, kaempferol and vitexin. Five novel components were identified, for the first time in fenugreek aerial parts, as kaempferol 3-O-β-d-glucopyranoside, kaempferol 7-O-glucoside, kaempferol 3-O-α-l-rhamnosyl (1→2 β-d-xyloside, kaempferol 7-O-β-d-glucopyranosyl (1–4 β-d-glucopyranoside and kaempferol 3-O-β-glucosyl (1→2 (6′-O-acetyl-β-d-galactoside, along with other known compounds of this species. To operate with the maximum efficiency, the allelopathic potential of a given plant, our study showed that it would be advisable to identify the most productive developmental stage of allelochemicals. Similarly, it seems that mixoploidy would be a simple and effective biotechnology tool to improve (in quantity and quality the allelochemicals’ production, since the extracts’ toxicity of diploid and mixoploid plants, was different.

  16. Multifaceted biological insights from a draft genome sequence of the tobacco hornworm moth, Manduca sexta

    Science.gov (United States)

    Kanost, Michael R.; Arrese, Estela L.; Cao, Xiaolong; Chen, Yun-Ru; Chellapilla, Sanjay; Goldsmith, Marian R; Grosse-Wilde, Ewald; Heckel, David G.; Herndon, Nicolae; Jiang, Haobo; Papanicolaou, Alexie; Qu, Jiaxin; Soulages, Jose L.; Vogel, Heiko; Walters, James; Waterhouse, Robert M.; Ahn, Seung-Joon; Almeida, Francisca C.; An, Chunju; Aqrawi, Peshtewani; Bretschneider, Anne; Bryant, William B.; Bucks, Sascha; Chao, Hsu; Chevignon, Germain; Christen, Jayne M.; Clarke, David F.; Dittmer, Neal T.; Ferguson, Laura C.F.; Garavelou, Spyridoula; Gordon, Karl H.J.; Gunaratna, Ramesh T.; Han, Yi; Hauser, Frank; He, Yan; Heidel-Fischer, Hanna; Hirsh, Ariana; Hu, Yingxia; Jiang, Hongbo; Kalra, Divya; Klinner, Christian; König, Christopher; Kovar, Christie; Kroll, Ashley R.; Kuwar, Suyog S.; Lee, Sandy L.; Lehman, Rüdiger; Li, Kai; Li, Zhaofei; Liang, Hanquan; Lovelace, Shanna; Lu, Zhiqiang; Mansfield, Jennifer H.; McCulloch, Kyle J.; Mathew, Tittu; Morton, Brian; Muzny, Donna M.; Neunemann, David; Ongeri, Fiona; Pauchet, Yannick; Pu, Ling-Ling; Pyrousis, Ioannis; Rao, Xiang-Jun; Redding, Amanda; Roesel, Charles; Sanchez-Gracia, Alejandro; Schaack, Sarah; Shukla, Aditi; Tetreau, Guillaume; Wang, Yang; Xiong, Guang-Hua; Traut, Walther; Walsh, Tom K.; Worley, Kim C.; Wu, Di; Wu, Wenbi; Wu, Yuan-Qing; Zhang, Xiufeng; Zou, Zhen; Zucker, Hannah; Briscoe, Adriana D.; Burmester, Thorsten; Clem, Rollie J.; Feyereisen, René; Grimmelikhuijzen, Cornelis J.P; Hamodrakas, Stavros J.; Hansson, Bill S.; Huguet, Elisabeth; Jermiin, Lars S.; Lan, Que; Lehman, Herman K.; Lorenzen, Marce; Merzendorfer, Hans; Michalopoulos, Ioannis; Morton, David B.; Muthukrishnan, Subbaratnam; Oakeshott, John G.; Palmer, Will; Park, Yoonseong; Passarelli, A. Lorena; Rozas, Julio; Schwartz, Lawrence M.; Smith, Wendy; Southgate, Agnes; Vilcinskas, Andreas; Vogt, Richard; Wang, Ping; Werren, John; Yu, Xiao-Qiang; Zhou, Jing-Jiang; Brown, Susan J.; Scherer, Steven E.; Richards, Stephen; Blissard, Gary W.

    2016-01-01

    Manduca sexta, known as the tobacco hornworm or Carolina sphinx moth, is a lepidopteran insect that is used extensively as a model system for research in insect biochemistry, physiology, neurobiology, development, and immunity. One important benefit of this species as an experimental model is its extremely large size, reaching more than 10 g in the larval stage. M. sexta larvae feed on solanaceous plants and thus must tolerate a substantial challenge from plant allelochemicals, including nicotine. We report the sequence and annotation of the M. sexta genome, and a survey of gene expression in various tissues and developmental stages. The Msex_1.0 genome assembly resulted in a total genome size of 419.4 Mbp. Repetitive sequences accounted for 25.8% of the assembled genome. The official gene set is comprised of 15,451 protein-coding genes, of which 2498 were manually curated. Extensive RNA-seq data from many tissues and developmental stages were used to improve gene models and for insights into gene expression patterns. Genome wide synteny analysis indicated a high level of macrosynteny in the Lepidoptera. Annotation and analyses were carried out for gene families involved in a wide spectrum of biological processes, including apoptosis, vacuole sorting, growth and development, structures of exoskeleton, egg shells, and muscle, vision, chemosensation, ion channels, signal transduction, neuropeptide signaling, neurotransmitter synthesis and transport, nicotine tolerance, lipid metabolism, and immunity. This genome sequence, annotation, and analysis provide an important new resource from a well-studied model insect species and will facilitate further biochemical and mechanistic experimental studies of many biological systems in insects. PMID:27522922

  17. Localization of Secondary Metabolites in Marine Invertebrates: Contribution of MALDI MSI for the Study of Saponins in Cuvierian Tubules of H. forskali

    Science.gov (United States)

    Meriaux, Céline; Bonnel, David; Salzet, Michel; Fournier, Isabelle; Wisztorski, Maxence

    2010-01-01

    Background Several species of sea cucumbers of the family Holothuriidae possess a particular mechanical defense system called the Cuvierian tubules (Ct). It is also a chemical defense system as triterpene glycosides (saponins) appear to be particularly concentrated in Ct. In the present study, the precise localization of saponins in the Ct of Holothuria forskali is investigated. Classical histochemical labeling using lectin was firstly performed but did not generate any conclusive results. Thus, MALDI mass spectrometry Imaging (MALDI-MSI) was directly applied and completed by statistical multivariate tests. A comparison between the tubules of relaxed and stressed animals was realized. Results These analyses allowed the detection of three groups of ions, corresponding to the isomeric saponins of the tubules. Saponins detected at m/z 1287 and 1303 were the most abundant and were apparently localized in the connective tissue of the tubules of both relaxed and stressed individuals. Saponins at m/z 1125 and 1141 were detected in lower amount and were present in tissues of relaxed animals. Finally, saponin ions at 1433, 1449, 1463 and 1479 were observed in some Ct of stressed holothuroids in the outer part of the connective tissue. The saponin group m/z 14xx seems therefore to be stress-specific and could originate from modifications of the saponins with m/z of 11xx. Conclusions All the results taken together indicate a complex chemical defense mechanism with, for a single organ, different sets of saponins originating from different cell populations and presenting different responses to stress. The present study also reflects that MALDI-MSI is a valuable tool for chemical ecology studies in which specific chemical signalling molecules like allelochemicals or pheromones have to be tracked. This report represents one of the very first studies using these tools to provide a functional and ecological understanding of the role of natural products from marine invertebrates

  18. Chemical defense in Elodea nuttallii reduces feeding and growth of aquatic herbivorous Lepidoptera.

    Science.gov (United States)

    Erhard, Daniela; Pohnert, Georg; Gross, Elisabeth M

    2007-08-01

    The submersed macrophyte Elodea nuttallii (Hydrocharitaceae) is invasive in Europe and frequently found in aquatic plant communities. Many invertebrate herbivores, such as larvae of the generalist aquatic moth, Acentria ephemerella (Lepidoptera, Pyralidae), avoid feeding on E. nuttallii and preferably consume native species. First instar larvae exhibited a high mortality on E. nuttallii compared to the native macrophyte Potamogeton perfoliatus. Mortality of older larvae was also high when fed E. nuttallii exposed to high light intensities. Growth of older larvae was strongly reduced on E. nuttallii compared to pondweeds (Potamogeton lucens). Neither differences in nitrogen nor phosphorus content explained the different performance on these submerged macrophytes, but plants differed in their flavonoid content. To investigate whether plant-derived allelochemicals from E. nuttallii affect larval performance in the same way as live plants, we developed a functional bioassay, in which Acentria larvae were reared on artificial diets. We offered larvae Potamogeton leaf disks coated with crude Elodea extracts and partially purified flavonoids. Elodea extracts deterred larvae from feeding on otherwise preferred Potamogeton leaves, and yet, unknown compounds in the extracts reduced growth and survival of Acentria. The flavonoid fraction containing luteolin-7-O-diglucuronide, apigenin-7-O-diglucuronide, and chrysoeriol-7-O-diglucuronide strongly reduced feeding of larvae, but did not increase mortality. The concentrations of these compounds in our assays were 0.01-0.09% of plant dry mass, which is in the lower range of concentrations found in the field (0.02-1.2%). Chemical defense in E. nuttallii thus plays an ecologically relevant role in this aquatic plant-herbivore system.

  19. Application of PCR-denaturing-gradient gel electrophoresis (DGGE) method to examine microbial community structure in asparagus fields with growth inhibition due to continuous cropping.

    Science.gov (United States)

    Urashima, Yasufumi; Sonoda, Takahiro; Fujita, Yuko; Uragami, Atsuko

    2012-01-01

    Growth inhibition due to continuous cropping of asparagus is a major problem; the yield of asparagus in replanted fields is low compared to that in new fields, and missing plants occur among young seedlings. Although soil-borne disease and allelochemicals are considered to be involved in this effect, this is still controversial. We aimed to develop a technique for the biological field diagnosis of growth inhibition due to continuous cropping. Therefore, in this study, fungal community structure and Fusarium community structure in continuously cropped fields of asparagus were analyzed by polymerase chain reaction/denaturing-gradient gel electrophoresis (PCR-DGGE). Soil samples were collected from the Aizu region of Fukushima Prefecture, Japan. Soil samples were taken from both continuously cropped fields of asparagus with growth inhibition and healthy neighboring fields of asparagus. The soil samples were collected from the fields of 5 sets in 2008 and 4 sets in 2009. We were able to distinguish between pathogenic and non-pathogenic Fusarium by using Alfie1 and Alfie2GC as the second PCR primers and PCR-DGGE. Fungal community structure was not greatly involved in the growth inhibition of asparagus due to continuous cropping. By contrast, the band ratios of Fusarium oxysporum f. sp. asparagi in growth-inhibited fields were higher than those in neighboring healthy fields. In addition, there was a positive correlation between the band ratios of Fusarium oxysporum f. sp. asparagi and the ratios of missing asparagus plants. We showed the potential of biological field diagnosis of growth inhibition due to continuous cropping of asparagus using PCR-DGGE.

  20. The ethnobotany of psychoactive plant use: a phylogenetic perspective

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    Nashmiah Aid Alrashedy

    2016-10-01

    Full Text Available Psychoactive plants contain chemicals that presumably evolved as allelochemicals but target certain neuronal receptors when consumed by humans, altering perception, emotion and cognition. These plants have been used since ancient times as medicines and in the context of religious rituals for their various psychoactive effects (e.g., as hallucinogens, stimulants, sedatives. The ubiquity of psychoactive plants in various cultures motivates investigation of the commonalities among these plants, in which a phylogenetic framework may be insightful. A phylogeny of culturally diverse psychoactive plant taxa was constructed with their psychotropic effects and affected neurotransmitter systems mapped on the phylogeny. The phylogenetic distribution shows multiple evolutionary origins of psychoactive families. The plant families Myristicaceae (e.g., nutmeg, Papaveraceae (opium poppy, Cactaceae (peyote, Convolvulaceae (morning glory, Solanaceae (tobacco, Lamiaceae (mints, Apocynaceae (dogbane have a disproportionate number of psychoactive genera with various indigenous groups using geographically disparate members of these plant families for the same psychoactive effect, an example of cultural convergence. Pharmacological traits related to hallucinogenic and sedative potential are phylogenetically conserved within families. Unrelated families that exert similar psychoactive effects also modulate similar neurotransmitter systems (i.e., mechanistic convergence. However, pharmacological mechanisms for stimulant effects were varied even within families suggesting that stimulant chemicals may be more evolutionarily labile than those associated with hallucinogenic and sedative effects. Chemically similar psychoactive chemicals may also exist in phylogenetically unrelated lineages, suggesting convergent evolution or differential gene regulation of a common metabolic pathway. Our study has shown that phylogenetic analysis of traditionally used psychoactive plants

  1. Effects of some sesquiterpenes on the stored-product insect Tenebrio molitor (Coleoptera: Tenebrionidae Efectos de algunos sesquiterpenos sobre el insecto de productos almacenados, Tenebrio molitor (Coleoptera: Tenebrionidae

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    Matías García

    2003-12-01

    Full Text Available In order to evaluate the allelochemical activity of some sesquiterpenes isolated from the native plant Tessaria absinthioides (Hook. et Arn. DC, and some semi synthetic derivatives against Tenebrio molitor L. larvae, we have developed bioassays directed to quantify repellency, larval mortality, and its effects on the development. Although costic aldehyde caused the maximum repellent effect, all the compounds showed a significant effect at some dose or time, indicating behavioral avoidance. The topical application of costic aldehyde produced the largest increase on the duration of the pupal stage. Tessaric acid exhibited the highest toxicity by topical application at the experiment closure. Both eremophilane-1(10,2,11(13-triene-12-oic, and -costic acids induced some morphological deformities.Con el objeto de evaluar sesquiterpenos aislados de la planta nativa Tessaria absinthioides (Hook et Arn y algunos derivados semisintéticos frente a larvas de Tenebrio molitor L., se desarrollaron bioensayos orientados a la cuantificación de la repelencia, mortalidad de larvas y efectos sobre el desarrollo. Aldehído cóstico produjo el mayor incremento en la duración del estado pupal por aplicación tópica. Acido tessárico exhibió el más alto porcentaje de mortalidad al finalizar el período de experimentación. Los productos eremophilan-1(10,2, 11(13-trien-12-oico y ácido -cóstico dieron lugar al mayor número de malformaciones. Si bien aldehído cóstico mostró la máxima actividad de repelencia, todos los compuestos evaluados produjeron efectos significativos en el ensayo de elección.

  2. Effects of Quinizarin and Five Synthesized Derivatives on Fifth Larval Instar Midgut Ecdysone 20-Monooxygenase Activity of the Tobacco Hornworm Manduca sexta

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    Christopher A. Drummond

    2014-01-01

    Full Text Available The plant allelochemical, quinizarin (1,4-dihydroxy-9,10-anthraquinone, and five anthraquinones that were synthesized from quinizarin, namely, 1,4-anthraquinone; 2-hydroxy-1,4-anthraquinone; 2-methoxy-1,4-anthraquinone; 9-hydroxy-1,4-anthraquinone; and 9-methoxy-1,4-anthraquinone, were assessed as to their effects on the essential, P450-dependent ecdysone 20-monooxygenase system of the insect model Manduca sexta (tobacco hornworm. This steroid hydroxylase converts the arthropod molting hormone, ecdysone, to the physiologically required 20-hydroxyecdysone form. M. sexta fifth larval instar midgut homogenates were incubated with increasing concentrations (10−8 to 10−3 M of each of the six anthraquinones followed by ecdysone 20-monooxygenase assessments using a radioenzymological assay. Four of the five anthraquinones exhibited I50’s of about 4×10-6 to 6×10-2 M. The most effective inhibitors were 2-methoxy-1,4-anthraquinone and 1,4-anthraquinone followed by 9-hydroxy-1,4 anthraquinone and 9-methoxy-1,4-anthraquinone. At lower concentrations the latter anthraquinone stimulated E20M activity. Quinizarin was less inhibitory and 2-hydroxy-1,4-anthraquinone was essentially without effect. Significantly, these studies make evident for the first time that anthraquinones can affect insect E20M activity, and thus insect endocrine regulation and development, and that a relationship between anthraquinone structure and effectiveness is apparent. These studies represent the first demonstrations of anthraquinones affecting any steroid hydroxylase system.

  3. Phenolics from Ageratina adenophora roots and their phytotoxic effects on Arabidopsis thaliana seed germination and seedling growth.

    Science.gov (United States)

    Zhou, Zhong-Yu; Liu, Wan-Xue; Pei, Gang; Ren, Hui; Wang, Jing; Xu, Qiao-Lin; Xie, Hai-Hui; Wan, Fang-Hao; Tan, Jian-Wen

    2013-12-04

    A bioassay-directed phytochemical study was conducted to investigate potential allelochemicals in the roots of the invasive plant Ageratina adenophora. Eleven phenolic compounds, including seven new ones, 7-hydroxy-8,9-dehydrothymol 9-O-trans-ferulate (1), 7-hydroxythymol 9-O-trans-ferulate (2), 7,8-dihydroxythymol 9-O-trans-ferulate (3), 7,8-dihydroxythymol 9-O-cis-ferulate (4), methyl (7R)-3-deoxy-4,5-epoxy-D-manno-2-octulosonate 8-O-trans-p-coumarate (5), methyl (7R)-3-deoxy-4,5-epoxy-D-manno-2-octulosonate 8-O-cis-p-coumarate (6), and 3-(2-hydroxyphenyl)propyl methyl malonate (7), were isolated from a bioactive subfraction of the ethanol extract of the roots of A. adenophora. The new structures were established on the basis of detailed spectroscopic analysis. The potential phytotoxic effects of these compounds on the germination of Arabidopsis thaliana seeds were tested by a filter paper assay. Compound 7 and known compounds 3-(2-hydroxyphenyl)-1-propanol (8) and o-coumaric acid (9) remarkably showed inhibition activity against Arabidopsis seed germination at a concentration of 1.0 mM. Compounds 1, 2, 5, 6, and 10 showed slight inhibitory activity at the test concentration after treatment for 3 days, while the other compounds showed no obvious inhibitory effects. Moreover, 7-9 were further found to show obvious inhibitory activity on retarding the seedling growth of Ar. thaliana cultured in soil medium.

  4. Broomrape weeds. Underground mechanisms of parasitism and associated strategies for their control: a review.

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    Monica eFernandez-Aparicio

    2016-02-01

    Full Text Available Broomrapes are plant-parasitic weeds which constitute one of the most difficult-to-control of all biotic constraints that affect crops in Mediterranean, central and eastern Europe, and Asia. Due to their physical and metabolic overlap with the crop, their underground parasitism, their achlorophyllous nature, and hardly destructible seed bank, broomrape weeds are usually not controlled by management strategies designed for non-parasitic weeds. Instead, broomrape are in a current state of intensification and spread due to lack of broomrape-specific control programs, unconscious introduction to new areas and may be decline of herbicide use and global warming to a lesser degree. We reviewed relevant facts about the biology and physiology of broomrape weeds and the major feasible control strategies. The points of vulnerability of some underground events, key for their parasitism such as crop-induced germination or haustorial development are reviewed as inhibition targets of the broomrape-crop association. Among the reviewed strategies are those aimed 1 to reduce broomrape seed bank viability, such as fumigation, herbigation, solarization and use of broomrape-specific pathogens; 2 diversion strategies to reduce the broomrape ability to timely detect the host such as those based on promotion of suicidal germination, on introduction of allelochemical interference, or on down-regulating host exudation of germination-inducing factors; 3 strategies to inhibit the capacity of the broomrape seedling to penetrate the crop and connect with the vascular system, such as biotic or abiotic inhibition of broomrape radicle growth, crop resistance to broomrape penetration either natural, genetically engineered or elicited by biotic- or abiotic-resistance-inducing agents and 4 strategies acting once broomrape seedling has bridged its vascular system with that of the host, aimed to impede or to endure the parasitic sink such as those based on the delivery of herbicides

  5. Broomrape Weeds. Underground Mechanisms of Parasitism and Associated Strategies for their Control: A Review

    Science.gov (United States)

    Fernández-Aparicio, Mónica; Reboud, Xavier; Gibot-Leclerc, Stephanie

    2016-01-01

    Broomrapes are plant-parasitic weeds which constitute one of the most difficult-to-control of all biotic constraints that affect crops in Mediterranean, central and eastern Europe, and Asia. Due to their physical and metabolic overlap with the crop, their underground parasitism, their achlorophyllous nature, and hardly destructible seed bank, broomrape weeds are usually not controlled by management strategies designed for non-parasitic weeds. Instead, broomrapes are in current state of intensification and spread due to lack of broomrape-specific control programs, unconscious introduction to new areas and may be decline of herbicide use and global warming to a lesser degree. We reviewed relevant facts about the biology and physiology of broomrape weeds and the major feasible control strategies. The points of vulnerability of some underground events, key for their parasitism such as crop-induced germination or haustorial development are reviewed as inhibition targets of the broomrape-crop association. Among the reviewed strategies are those aimed (1) to reduce broomrape seed bank viability, such as fumigation, herbigation, solarization and use of broomrape-specific pathogens; (2) diversion strategies to reduce the broomrape ability to timely detect the host such as those based on promotion of suicidal germination, on introduction of allelochemical interference, or on down-regulating host exudation of germination-inducing factors; (3) strategies to inhibit the capacity of the broomrape seedling to penetrate the crop and connect with the vascular system, such as biotic or abiotic inhibition of broomrape radicle growth and crop resistance to broomrape penetration either natural, genetically engineered or elicited by biotic- or abiotic-resistance-inducing agents; and (4) strategies acting once broomrape seedling has bridged its vascular system with that of the host, aimed to impede or to endure the parasitic sink such as those based on the delivery of herbicides via

  6. Heat shock and plant leachates regulate seed germination of the endangered carnivorous plant Drosophyllum lusitanicum

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    S. Gómez-González

    2018-01-01

    Full Text Available In fire-prone ecosystems, many plant species have specialized mechanisms of seed dormancy that ensure a successful recruitment after fire. A well-documented mechanism is the germination stimulated by fire-related cues, such as heat shock and smoke. However, less is known about the role of inhibitory germination signals (e.g. allelopathy in regulating post-fire recruitment. Plant leachates derived from the unburned vegetation can enforce dormancy by means of allelopathic compounds, acting as a signal of unfavourable (highly competitive niche for germination in pyrophyte species. Here, we assessed the separate effects of heat shock and plant leachates on seed germination of Drosophyllum lusitanicum, an endangered carnivorous plant endemic to Mediterranean fire-prone heathlands. We performed a germination experiment in which seeds were subjected to three treatments: (1 5 min at 100 °C, (2 watering with plant leachate, and (3 control. Germination rate and seed viability was determined after 63 days. Heat shock stimulated seed germination in D. lusitanicum while plant leachates had inhibitory germination effects without reducing seed viability. Thus, both positive and negative signals could be involved in its successful post-fire recruitment. Fire would break seed dormancy and stimulate seed germination of D. lusitanicum through high temperatures, but also by eliminating allelochemical compounds from the soil. These results help to understand the population dynamics patterns found for D. lusitanicum in natural populations, and highlight the role of fire in the ecology and conservation of this endangered species. Seed dormancy imposed by plant-derived leachates as an adaptive mechanism should be considered more in fire ecology theory.

  7. The ABC gene family in arthropods: comparative genomics and role in insecticide transport and resistance.

    Science.gov (United States)

    Dermauw, Wannes; Van Leeuwen, Thomas

    2014-02-01

    About a 100 years ago, the Drosophila white mutant marked the birth of Drosophila genetics. The white gene turned out to encode the first well studied ABC transporter in arthropods. The ABC gene family is now recognized as one of the largest transporter families in all kingdoms of life. The majority of ABC proteins function as primary-active transporters that bind and hydrolyze ATP while transporting a large diversity of substrates across lipid membranes. Although extremely well studied in vertebrates for their role in drug resistance, less is known about the role of this family in the transport of endogenous and exogenous substances in arthropods. The ABC families of five insect species, a crustacean and a chelicerate have been annotated in some detail. We conducted a thorough phylogenetic analysis of the seven arthropod and human ABC protein subfamilies, to infer orthologous relationships that might suggest conserved function. Most orthologous relationships were found in the ABCB half transporter, ABCD, ABCE and ABCF subfamilies, but specific expansions within species and lineages are frequently observed and discussed. We next surveyed the role of ABC transporters in the transport of xenobiotics/plant allelochemicals and their involvement in insecticide resistance. The involvement of ABC transporters in xenobiotic resistance in arthropods is historically not well documented, but an increasing number of studies using unbiased differential gene expression analysis now points to their importance. We give an overview of methods that can be used to link ABC transporters to resistance. ABC proteins have also recently been implicated in the mode of action and resistance to Bt toxins in Lepidoptera. Given the enormous interest in Bt toxicology in transgenic crops, such findings will provide an impetus to further reveal the role of ABC transporters in arthropods. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Glutathione-S-transferase profiles in the emerald ash borer, Agrilus planipennis.

    Science.gov (United States)

    Rajarapu, Swapna Priya; Mittapalli, Omprakash

    2013-05-01

    The emerald ash borer, Agrilus planipennis Fairmaire is a recently discovered invasive insect pest of ash, Fraxinus spp. in North America. Glutathione-S-transferases (GST) are a multifunctional superfamily of enzymes which function in conjugating toxic compounds to less toxic and excretable forms. In this study, we report the molecular characterization and expression patterns of different classes of GST genes in different tissues and developmental stages plus their specific activity. Multiple sequence alignment of all six A. planipennis GSTs (ApGST-E1, ApGST-E2, ApGST-E3, ApGST-O1, ApGST-S1 and ApGST-μ1) revealed conserved features of insect GSTs and a phylogenetic analysis grouped the GSTs within the epsilon, sigma, omega and microsomal classes of GSTs. Real time quantitative PCR was used to study field collected samples. In larval tissues high mRNA levels for ApGST-E1, ApGST-E3 and ApGST-O1 were obtained in the midgut and Malpighian tubules. On the other hand, ApGST-E2 and ApGST-S1 showed high mRNA levels in fat body and ApGST-μ1 showed constitutive levels in all the tissues assayed. During development, mRNA levels for ApGST-E2 were observed to be the highest in feeding instars, ApGST-S1 in prepupal instars; while the others showed constitutive patterns in all the developmental stages examined. At the enzyme level, total GST activity was similar in all the tissues and developmental stages assayed. Results obtained suggest that A. planipennis is potentially primed with GST-driven detoxification to metabolize ash allelochemicals. To our knowledge this study represents the first report of GSTs in A. planipennis and also in the family of wood boring beetles. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Bioherbicides: Current knowledge on weed control mechanism.

    Science.gov (United States)

    Radhakrishnan, Ramalingam; Alqarawi, Abdulaziz A; Abd Allah, Elsayed Fathi

    2018-04-17

    Weed control is a challenging event during crop cultivation. Integrated management, including the application of bioherbicides, is an emerging method for weed control in sustainable agriculture. Plant extracts, allelochemicals and some microbes are utilized as bioherbicides to control weed populations. Bioherbicides based on plants and microbes inhibit the germination and growth of weeds; however,few studies conducted in weed physiology. This review ascribes the current knowledge of the physiological changes in weeds that occur during the exposure to bioherbicides. Plant extracts or metabolites are absorbed by weed seeds, which initiates damage to the cell membrane, DNA, mitosis, amylase activity and other biochemical processes and delays or inhibits seed germination. The growth of weeds is also retarded due to low rates of root-cell division, nutrient uptake, photosynthetic pigment synthesis, and plant growth hormone synthesis, while the productions of reactive oxygen species (ROS) and stress-mediated hormones increase, including irregular antioxidant activity. However, lytic enzymes and toxic substances secreted from microbes degrade the weed seed coat and utilize the endosperm for survival, which inhibits seed germination. The microbes grow through the intercellular spaces to reach the root core, and the deposition of toxins in the cells affects cell division and cellular functions. Some of the metabolites of deleterious microbes cause disease, necrosis and chlorosis,which inhibit the germination and growth of weed seeds by suppressing photosynthesis and gibberellin activities and enhancing ROS, abscisic acid and ethylene. This review explains the effects of bioherbicides (derived from plants and microbes) on weed-plant physiology to elucidate their modes of action. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Identification and Phytotoxicity Assessment of Phenolic Compounds in Chrysanthemoides monilifera subsp. monilifera (Boneseed.

    Directory of Open Access Journals (Sweden)

    Md Abdullah Yousuf Al Harun

    Full Text Available Chrysanthemoides monilifera subsp. monilifera (boneseed, a weed of national significance in Australia, threatens indigenous species and crop production through allelopathy. We aimed to identify phenolic compounds produced by boneseed and to assess their phytotoxicity on native species. Phenolic compounds in water and methanol extracts, and in decomposed litter-mediated soil leachate were identified using HPLC, and phytotoxicity of identified phenolics was assessed (repeatedly through a standard germination bioassay on native Isotoma axillaris. The impact of boneseed litter on native Xerochrysum bracteatum was evaluated using field soil in a greenhouse. Collectively, we found the highest quantity of phenolic compounds in boneseed litter followed by leaf, root and stem. Quantity varied with extraction media. The rank of phenolics concentration in boneseed was in the order of ferulic acid > phloridzin > catechin > p-coumaric acid and they inhibited germination of I. axillaris with the rank of ferulic acid > catechin > phloridzin > p-coumaric acid. Synergistic effects were more severe compared to individual phenolics. The litter-mediated soil leachate (collected after15 days exhibited strong phytotoxicity to I. axillaris despite the level of phenolic compounds in the decomposed leachate being decreased significantly compared with their initial level. This suggests the presence of other unidentified allelochemicals that individually or synergistically contributed to the phytotoxicity. Further, the dose response phytotoxic impacts exhibited by the boneseed litter-mediated soil to native X. bracteatum in a more naturalistic greenhouse experiment might ensure the potential allelopathy of other chemical compounds in the boneseed invasion. The reduction of leaf relative water content and chlorophyll level in X. bracteatum suggest possible mechanisms underpinning plant growth inhibition caused by boneseed litter allelopathy. The presence of a substantial

  11. Allelopathy and resource competition: the effects of Phragmites australis invasion in plant communities.

    Science.gov (United States)

    Uddin, Md Nazim; Robinson, Randall William

    2017-12-01

    Phragmites australis, a ubiquitous wetland plant, has been considered one of the most invasive species in the world. Allelopathy appears to be one of the invasion mechanisms, however, the effects could be masked by resource competition among target plants. The difficulty of distinguishing allelopathy from resource competition among plants has hindered investigations of the role of phytotoxic allelochemicals in plant communities. This has been addressed via experiments conducted in both the greenhouse and laboratory by growing associated plants, Melaleuca ericifolia, Rumex conglomeratus, and model plant, Lactuca sativa at varying densities with the allelopathic plant, P. australis, its litter and leachate of P. australis litter. This study investigated the potential interacting influences of allelopathy and resource competition on plant growth-density relationships. In greenhouse, the root exudates mediated effects showed the strongest growth inhibition of M. ericifolia at high density whereas litter mediated results revealed increased growth at medium density treatments compared to low and high density. Again, laboratory experiments related to seed germination and seedling growth of L. sativa and R. conglomeratus exhibited phytotoxicity decreased showing positive growth as plant density increased and vice versa. Overall, the differential effects were observed among experiments but maximum individual plant biomass and some other positive effects on plant traits such as root and shoot length, chlorophyll content occurred at an intermediate density. This was attributed to the sharing of the available phytotoxin among plants at high densities which is compatible to density-dependent phytotoxicity model. The results demonstrated that plant-plant interference is the combined effect of allelopathy and resource competition with many other factors but this experimental design, target-neighbor mixed-culture in combination of plant grown at varying densities with varying

  12. Identification and Phytotoxicity Assessment of Phenolic Compounds in Chrysanthemoides monilifera subsp. monilifera (Boneseed).

    Science.gov (United States)

    Al Harun, Md Abdullah Yousuf; Johnson, Joshua; Uddin, Md Nazim; Robinson, Randall W

    2015-01-01

    Chrysanthemoides monilifera subsp. monilifera (boneseed), a weed of national significance in Australia, threatens indigenous species and crop production through allelopathy. We aimed to identify phenolic compounds produced by boneseed and to assess their phytotoxicity on native species. Phenolic compounds in water and methanol extracts, and in decomposed litter-mediated soil leachate were identified using HPLC, and phytotoxicity of identified phenolics was assessed (repeatedly) through a standard germination bioassay on native Isotoma axillaris. The impact of boneseed litter on native Xerochrysum bracteatum was evaluated using field soil in a greenhouse. Collectively, we found the highest quantity of phenolic compounds in boneseed litter followed by leaf, root and stem. Quantity varied with extraction media. The rank of phenolics concentration in boneseed was in the order of ferulic acid > phloridzin > catechin > p-coumaric acid and they inhibited germination of I. axillaris with the rank of ferulic acid > catechin > phloridzin > p-coumaric acid. Synergistic effects were more severe compared to individual phenolics. The litter-mediated soil leachate (collected after15 days) exhibited strong phytotoxicity to I. axillaris despite the level of phenolic compounds in the decomposed leachate being decreased significantly compared with their initial level. This suggests the presence of other unidentified allelochemicals that individually or synergistically contributed to the phytotoxicity. Further, the dose response phytotoxic impacts exhibited by the boneseed litter-mediated soil to native X. bracteatum in a more naturalistic greenhouse experiment might ensure the potential allelopathy of other chemical compounds in the boneseed invasion. The reduction of leaf relative water content and chlorophyll level in X. bracteatum suggest possible mechanisms underpinning plant growth inhibition caused by boneseed litter allelopathy. The presence of a substantial quantity of free

  13. Flavin-dependent monooxygenases as a detoxification mechanism in insects: new insights from the arctiids (lepidoptera.

    Directory of Open Access Journals (Sweden)

    Sven Sehlmeyer

    2010-05-01

    Full Text Available Insects experience a wide array of chemical pressures from plant allelochemicals and pesticides and have developed several effective counterstrategies to cope with such toxins. Among these, cytochrome P450 monooxygenases are crucial in plant-insect interactions. Flavin-dependent monooxygenases (FMOs seem not to play a central role in xenobiotic detoxification in insects, in contrast to mammals. However, the previously identified senecionine N-oxygenase of the arctiid moth Tyria jacobaeae (Lepidoptera indicates that FMOs have been recruited during the adaptation of this insect to plants that accumulate toxic pyrrolizidine alkaloids. Identification of related FMO-like sequences of various arctiids and other Lepidoptera and their combination with expressed sequence tag (EST data and sequences emerging from the Bombyx mori genome project show that FMOs in Lepidoptera form a gene family with three members (FMO1 to FMO3. Phylogenetic analyses suggest that FMO3 is only distantly related to lepidopteran FMO1 and FMO2 that originated from a more recent gene duplication event. Within the FMO1 gene cluster, an additional gene duplication early in the arctiid lineage provided the basis for the evolution of the highly specific biochemical, physiological, and behavioral adaptations of these butterflies to pyrrolizidine-alkaloid-producing plants. The genes encoding pyrrolizidine-alkaloid-N-oxygenizing enzymes (PNOs are transcribed in the fat body and the head of the larvae. An N-terminal signal peptide mediates the transport of the soluble proteins into the hemolymph where PNOs efficiently convert pro-toxic pyrrolizidine alkaloids into their non-toxic N-oxide derivatives. Heterologous expression of a PNO of the generalist arctiid Grammia geneura produced an N-oxygenizing enzyme that shows noticeably expanded substrate specificity compared with the related enzyme of the specialist Tyria jacobaeae. The data about the evolution of FMOs within lepidopteran insects

  14. Ecological shifts in Mediterranean coralligenous assemblages related to gorgonian forest loss.

    Directory of Open Access Journals (Sweden)

    Massimo Ponti

    Full Text Available Mediterranean gorgonian forests are threatened by several human activities and are affected by climatic anomalies that have led to mass mortality events in recent decades. The ecological role of these habitats and the possible consequence of their loss are poorly understood. Effects of gorgonians on the recruitment of epibenthic organisms were investigated by manipulating presence of gorgonians on experimental panels at 24 m depth, for Eunicella cavolinii, and at 40 m depth, for Paramuricea clavata, at two sites: Tavolara Island (Tyrrhenian Sea and Portofino Promontory (Ligurian Sea. After 4 months, the most abundant taxa on the panels were encrusting green algae, erect red algae and crustose coralline algae at 24 m depth and encrusting brown algae and erect red algae at 40 m depth. Assemblages on the panels were significantly affected by the presence of the gorgonians, although effects varied across sites and between gorgonian species. Species diversity and evenness were lower on panels with gorgonian branches. Growth of erect algae and recruitment of serpulid polychaetes were also affected by the presence of the gorgonians, primarily at Tavolara. Crustose coralline algae and erect sponges were more abundant on E. cavolinii panels at 24 m depth, while encrusting bryozoans were more abundant on P. clavata panels at 40 m depth. Effects of gorgonians on recruited assemblages could be due to microscale modification of hydrodynamics and sediment deposition rate, or by a shading effect reducing light intensity. Gorgonians may also intercept settling propagules, compete for food with the filter-feeders and/or for space by producing allelochemicals. Presence of gorgonians mainly limits the growth of erect algae and enhances the abundance of encrusting algae and sessile invertebrates. Therefore, the gorgonian disappearances may cause a shift from assemblages characterised by crustose coralline algae to filamentous algae assemblages, decreasing

  15. Carotenoids Database: structures, chemical fingerprints and distribution among organisms.

    Science.gov (United States)

    Yabuzaki, Junko

    2017-01-01

    To promote understanding of how organisms are related via carotenoids, either evolutionarily or symbiotically, or in food chains through natural histories, we built the Carotenoids Database. This provides chemical information on 1117 natural carotenoids with 683 source organisms. For extracting organisms closely related through the biosynthesis of carotenoids, we offer a new similarity search system 'Search similar carotenoids' using our original chemical fingerprint 'Carotenoid DB Chemical Fingerprints'. These Carotenoid DB Chemical Fingerprints describe the chemical substructure and the modification details based upon International Union of Pure and Applied Chemistry (IUPAC) semi-systematic names of the carotenoids. The fingerprints also allow (i) easier prediction of six biological functions of carotenoids: provitamin A, membrane stabilizers, odorous substances, allelochemicals, antiproliferative activity and reverse MDR activity against cancer cells, (ii) easier classification of carotenoid structures, (iii) partial and exact structure searching and (iv) easier extraction of structural isomers and stereoisomers. We believe this to be the first attempt to establish fingerprints using the IUPAC semi-systematic names. For extracting close profiled organisms, we provide a new tool 'Search similar profiled organisms'. Our current statistics show some insights into natural history: carotenoids seem to have been spread largely by bacteria, as they produce C30, C40, C45 and C50 carotenoids, with the widest range of end groups, and they share a small portion of C40 carotenoids with eukaryotes. Archaea share an even smaller portion with eukaryotes. Eukaryotes then have evolved a considerable variety of C40 carotenoids. Considering carotenoids, eukaryotes seem more closely related to bacteria than to archaea aside from 16S rRNA lineage analysis. : http://carotenoiddb.jp. © The Author(s) 2017. Published by Oxford University Press.

  16. Biochar reduces copper toxicity in Chenopodium quinoa Willd. In a sandy soil.

    Science.gov (United States)

    Buss, Wolfram; Kammann, Claudia; Koyro, Hans-Werner

    2012-01-01

    Mining, smelting, land applications of sewage sludge, the use of fungicides containing copper (Cu), and other human activities have led to widespread soil enrichment and contamination with Cu and potentially toxic conditions. Biochar (BC) can adsorb several substances, ranging from herbicides to plant-inhibiting allelochemicals. However, the range of potential beneficial effects on early-stage plant growth with regard to heavy metal toxicity is largely unexplored. We investigated the ameliorating properties of a forestry-residue BC under Cu toxicity conditions on early plant growth. Young quinoa plants () were grown in the greenhouse in the presence of 0, 2, and 4% BC application (w/w) added to a sandy soil with 0, 50, or 200 μg g Cu supplied. The plants without BC showed severe stress symptoms and reduced growth shortly after Cu application of 50 μg g and died at 200 μg Cu g. Increasing BC concentrations in the growth medium significantly increased the plant performance without Cu toxicity or under Cu stress. At the 4% BC application rate, the plants with 200 μg g Cu almost reached the same biomass as in the control treatment. In the presence of BC, less Cu entered the plant tissues, which had reduced Cu concentrations in the order roots, shoots, leaves. The amelioration effect also was reflected in the plant-soil system CO gas exchange, which showed clear signs of improvement with BC presence. The most likely ameliorating mechanisms were adsorption of Cu to negatively charged BC surfaces and an improvement of the water supply. Overall, BC seems to be a beneficial amendment with the potential to ameliorate Cu toxicity in sandy soils. Further research with a broad spectrum of different soil types, BCs, and crop plants is required. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  17. Study on the mechanism of allelopathic influence on cyanobacteria and chlorophytes by submerged macrophyte (Myriophyllum spicatum) and its secretion

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Junying [State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Liu Biyun [State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072 (China); Wang Jing; Gao Yunni [State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Wu Zhenbin, E-mail: wuzb@ihb.ac.cn [State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072 (China)

    2010-06-10

    For revealing the mechanism of allelopathic influence on phytoplankton by aquatic macrophytes, the growth and photosynthetic activities of cyanobacteria Microcystis aeruginosa and the chlorophyte Selenastrum capricornutum were investigated when they coexisted with submerged macrophyte Myriophyllum spicatum and were exposed to allelopathic polyphenols: pyrogallic acid (PA), gallic acid (GA), ellagic acid (EA) and (+)-catechin (CA). According to the results of coexistence assays, the non-photochemical quenching (NPQ) and effective quantum efficiency (YII) of M. aeruginosa were affected earlier and more rapidly than the cell density. However, the influence of M. spicatum on S. capricornutum was not found. When the Toxicity Index (TI) was applied to evaluate the combined effects of binary and multiple mixtures of polyphenols, it was found that the four tested polyphenols with the proportion identified in the M. spicatum-cultured solution were observed to present synergistic effect (0.36-0.49) according to the cell density, NPQ and YII of M. aeruginosa. With the combined effects of polyphenols on S. capricornutum, only additive action (0.52-1.62) was found. On the other hand, PA (2.97 mg L{sup -1}), GA (2.65 mg L{sup -1}) caused significant reductions of photosystem II (PSII) and whole electron transport chain activities of M. aeruginosa by 71.43 and 18.37%, 70.95 and 40.77% (P < 0.05), respectively, after 24-h exposure, but no inhibition effect was found in S. capricornutum. The dark respiration and photosystem I (PSI) activities of M. aeruginosa were significantly increased by exposure to PA and GA (P < 0.05). Nevertheless, EA and CA had no influence on the electron transport activities of the tested organisms. These results indicate that the reduction in photosynthetic activity of M. aeruginosa and the synergistic effect of allelochemicals may be two important causes for the inhibition of undesired phytoplankton by submersed macrophytes in natural aquatic ecosystems

  18. Mechanisms for regulating oxygen toxicity in phytophagous insects.

    Science.gov (United States)

    Ahmad, S; Pardini, R S

    1990-01-01

    The antioxidant enzymatic defense of insects for the regulation of oxygen toxicity was investigated. Insect species examined were lepidopterous larvae of the cabbage looper (Trichoplusia ni), southern armyworm (Spodoptera eridania), and black swallowtail (Papilio polyxenes). These phytophagous species are subject to both endogenous and exogenous sources of oxidative stress from toxic oxygen radicals, hydrogen peroxide (H2O2) and lipid peroxides (LOOH). In general, the constitutive levels of the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GT), and its peroxidase activity (GTpx), and glutathione reductase (GR), correlate well with natural feeding habits of these insects and their relative susceptibility to prooxidant plant allelochemicals, quercetin (a flavonoid), and xanthotoxin (a photoactive furanocoumarin). Induction of SOD activity which rapidly destroys superoxide radicals, appears to be the main response to dietary prooxidant exposure. A unique observation includes high constitutive activity of CAT and a broader subcellular distribution in all three insects than observed in most mammalian species. These attributes of CAT appear to be important in the prevention of excessive accumulation of cytotoxic H2O2. Unlike mammalian species, insects possess very low levels of a GPOX-like activity toward H2O2. Irrefutable proof that this activity is due to a selenium-dependent GPOX found in mammals, is lacking at this time. However, the activity of selenium-independent GTpx is unusually high in insects, suggesting that GTpx and not GPOX plays a prominent role in scavenging deleterious LOOHs. The GSSG generated from the GPOX and GTpx reactions may be reduced to GSH by GR activity. A key role of SOD in protecting insects from prooxidant toxicity was evident when its inhibition resulted in enhanced toxicity towards prooxidants. The role of antioxidant compounds in protecting these insects from toxic forms of oxygen has not been explored in

  19. Allelopathy of plants in space

    Science.gov (United States)

    Tomita-Yokotani, K.; Baba, K.; Fujii, Y.; Hashimoto, H.; Nakamura, T.; Yamashita, M.

    Allelopathy is a chemical way of interaction among many organisms living together on the earth, and forming ecological systems as the member of the biosphere. Biosynthesis of allelochemicals, their release, transport and sensing mechanism at the recipient organisms, which is associated with allelopathy, are under the influence of gravity in many aspects. Such gravitational action on the allelopathy could be ranged from perturbation on biochemical networks in the cells to macroscopic transportation phenomena around the organisms. If gravity is an environmental factor that governs those processes, allelopathy at the absence of gravity on space craft, or under the different magnitude of gravity on the outer planets might differ from allelopathy on the ground. Another important factor in allelopathy in space application is physical closure of living environment, and lack of natural process to decompose allelopathic chemicals or the sink among material circulation in the biosphere. Many organisms and ecological system may behave differently in spacecrafts or on outer planets, based on the modified inter-organisms and -species interactions associated with alleopahty. In order to examine allelopathy under exotic gravity and closed environment, we imposed pseudo-microgravity and physical closure on a plant-plant allelopathy system. Two plant species were co-cultured in a closed vessel, and gravity vector was randomized by the 3D-clinorotation. Velvet bean (Mucuna pruriens L.) is known to induce strong allelopathic action on many plant species. Velvet bean and lettuce was chosen as the pair. Growth of lettuce seedlings, co-cultured with velvet bean, was analyzed under the 3D-clinorotation, and compared it with growth of the ground control group. The degree of allelopathic suppression on the lettuce root growth was less on the 3D-clinorotation. L-DOPA (L-3,4-dihydroxy-phennylalanine), released from root is the major substance responsible to the allelopathy of velvet bean

  20. Papel dos tricomas glandulares da folha do tomateiro na oviposição de Tuta absoluta Role of tomato leaf glandular trichomes on oviposition of Tuta absoluta

    Directory of Open Access Journals (Sweden)

    Elsa Gilardón

    2001-03-01

    Full Text Available Os tricomas glandulares presentes nas folhas e ramos das plantas do gênero Lycopersicon são responsáveis pela secreção de metabólitos de diferentes naturezas. A presença de alguns desses compostos tem sido associada à resistência do tomate a diferentes insetos. A traça-do-tomateiro, Tuta absoluta (Meyrick, é uma das pragas mais nocivas da América do Sul. O adulto oviposita sobre as folhas do tomate e suas larvas abrem galerias no mesófilo das folhas, ramos, flores e frutos. As espécies silvestres do tomate conservam a capacidade de biossintetizar compostos químicos que lhes conferem resistência a esta praga. No presente trabalho, foi avaliada a preferência para oviposição desse inseto sobre folhas com e sem tricomas glandulares de L. esculentum (Mill. cv. Uco Plata, suscetível, e de L. hirsutum f. glabratum (Mull. PI 134417, espécie silvestre afim ao tomate, e resistente à traça. Os resultados sugerem que as fêmeas ovipositam indistintamente sobre as folhas de ambas espécies, independentemente da presença, ou não, dos tricomas glandulares. E a presença destes e de seus exsudatos não têm efeito inibidor na oviposição do inseto.In the genus Lycopersicon, different metabolites are secreted by the glandular trichomes of leaves and stems. These compounds have been associated to different tomato pests resistance. The South American tomato pinworm, Tuta absoluta (Meyrick, is one of the most harmful pests in South America. The females oviposit on tomato leaves and the larvae mine the leaf mesophyl, stems, flowers and fruits. Some wild accessions of Lycopersicon keep their capacity to synthesize allelochemicals that protect them from the pest. In this paper a comparison was made between the tomato pinworm oviposition on leaves with and without trichomes of L. esculentum (Mill. cv. Uco Plata, a susceptible cultivar, and L. hirsutum f. glabratum (Mull. PI 134417, a resistant wild accession. Results suggest that the female

  1. Study on the mechanism of allelopathic influence on cyanobacteria and chlorophytes by submerged macrophyte (Myriophyllum spicatum) and its secretion

    International Nuclear Information System (INIS)

    Zhu Junying; Liu Biyun; Wang Jing; Gao Yunni; Wu Zhenbin

    2010-01-01

    For revealing the mechanism of allelopathic influence on phytoplankton by aquatic macrophytes, the growth and photosynthetic activities of cyanobacteria Microcystis aeruginosa and the chlorophyte Selenastrum capricornutum were investigated when they coexisted with submerged macrophyte Myriophyllum spicatum and were exposed to allelopathic polyphenols: pyrogallic acid (PA), gallic acid (GA), ellagic acid (EA) and (+)-catechin (CA). According to the results of coexistence assays, the non-photochemical quenching (NPQ) and effective quantum efficiency (YII) of M. aeruginosa were affected earlier and more rapidly than the cell density. However, the influence of M. spicatum on S. capricornutum was not found. When the Toxicity Index (TI) was applied to evaluate the combined effects of binary and multiple mixtures of polyphenols, it was found that the four tested polyphenols with the proportion identified in the M. spicatum-cultured solution were observed to present synergistic effect (0.36-0.49) according to the cell density, NPQ and YII of M. aeruginosa. With the combined effects of polyphenols on S. capricornutum, only additive action (0.52-1.62) was found. On the other hand, PA (2.97 mg L -1 ), GA (2.65 mg L -1 ) caused significant reductions of photosystem II (PSII) and whole electron transport chain activities of M. aeruginosa by 71.43 and 18.37%, 70.95 and 40.77% (P < 0.05), respectively, after 24-h exposure, but no inhibition effect was found in S. capricornutum. The dark respiration and photosystem I (PSI) activities of M. aeruginosa were significantly increased by exposure to PA and GA (P < 0.05). Nevertheless, EA and CA had no influence on the electron transport activities of the tested organisms. These results indicate that the reduction in photosynthetic activity of M. aeruginosa and the synergistic effect of allelochemicals may be two important causes for the inhibition of undesired phytoplankton by submersed macrophytes in natural aquatic ecosystems, and

  2. Metabolitos secundários como fontes de bioherbicidas: situação actual e perspectivas Secondary metabolites as sources of bioherbicides: present situation and perspectives

    Directory of Open Access Journals (Sweden)

    L.S. Dias

    2007-01-01

    Full Text Available Metabolitos secundários produzidos e libertados por plantas, bactérias e fungos estão envolvidos numa variedade de processos ecológicos, nomeadamente como semioquímicos e alelopatinos. Adicionalmente, e para além das suas possíveis funções ecológicas, muitos dos metabolitos secundários são fitotóxicos, constituindo uma fonte relativamente inexplorada de novos herbicidas. Solanum nigrum (erva-moira é uma infestante importante e muito bem sucedida num grande número de culturas, nomeadamente hortícolas e será usada como exemplo principal das utilizações actuais de aleloquímicos vegetais bem como das perspectivas de utilização deste tipo de compostos como bioherbicidas. Nesse âmbito revêem-se as principais estratégias de pesquisa de bioherbicidas e apresenta-se o estado da arte dos modos de acção de aleloquímicos já comercializados como herbicidas (Bialaphos e PPT, patenteados (AAL-toxina e em investigação, quer produzidos por plantas superiores (sorgoleona e derivados do cineol quer de origem bacteriana (hidantocidina e fúngica (fumonisinas, coletotriquina.Secondary metabolites produced and released by plants, bacteria, and fungi are involved in a number of ecological processes, namely as semiochemicals and allelopathins. In addition, and beside their possible ecological roles, a greater number of secondary metabolites are phytotoxic and represent a relatively unexplored source of new herbicides. Solanum nigrum (black nightshade is an important and successful weed in many crops, namely in horticulture, and will be used as a major example of actual and prospective uses of phytoallelochemicals as bioherbicides. Therefore, the main strategies for bioherbicides search are reviewed and the state of art of the modes of action of allelochemicals is presented, including those already in use as herbicides (Bialaphos and PPT, patented (AAL-toxin, and under investigation, whether produced by plants (sorgoleone and cineol

  3. Allelopathic effect of black mustard tissues and root exudates on some crops and weeds Efeito alelopático de tecidos de mostarda-preta e exsudatos da raiz de algumas culturas e plantas daninhas

    Directory of Open Access Journals (Sweden)

    E Al-Sherif

    2013-03-01

    Full Text Available Laboratory and greenhouse experiments were conducted to evaluate the phytotoxic effect of black mustard extracts and root exudates on two crops: Trifolium alexandrinum and Triticum aestivum, and two weeds: Phalaris paradoxa and Sisymbrium irio. The seeds were treated with aqueous and ethanolic extracts and chloroform for eight days, or subjected to root exudates of just harvested mustard in a greenhouse for five weeks. High-performance liquid chromatography (HPLC was used to quantify phytotoxins from plant tissues. Seed germination of P. paradoxa was reduced with the lowest concentration of the different extracts. However, the aqueous extract at 4% completely curtailed the germination of all the target species. In general, plant extracts had a concentration-dependent reduction of seedling growth of the target species. However, the ethanolic extract, at the lowest concentration, has stimulated the shoot length of both T. alexandrinum and T. aestivum, and the root length of the former. Mustard root exudates inhibited emergence and growth of the target species throughout the experiment. Ferulic and syringic acids were the dominant allelochemicals found when HPLC was used.Experimentos de laboratório e estufa foram realizados para avaliar o efeito fitotóxico dos extratos de mostarda-preta e exsudatos de raiz de duas culturas: Trifolium alexandrinum e Triticum aestivum, bem como de duas plantas daninhas: Phalaris paradoxa e Sisymbrium irio. As sementes foram tratadas com extratos aquosos, etanólicos e clorofórmio por oito dias, ou submetidas a exsudatos de raiz de mostarda recém-colhidaem estufa durante cinco semanas. A cromatografia líquida de alto desempenho (HPLC foi usada para a quantificação de fitotoxinas a partir de tecidos de plantas. Sementes de P. paradoxa apresentam germinação reduzida com a menor concentração dos diferentes extratos. No entanto, o extrato aquoso a 4% restringiu completamente a germinação de todas as esp

  4. [Effects of different amendments on contents of phenolic acids and specific microbes in rhizosphere of Pseudostellaria heterophylla.

    Science.gov (United States)

    Wu, Lin Kun; Wu, Hong Miao; Zhu, Quan; Chen, Jun; Wang, Juan Ying; Wu, Yan Hong; Lin, Sheng; Lin, Wen Xiong

    2016-11-18

    consecutive monoculture problems of P. heterophylla may be due to the rapid proliferation of host-specific pathogens, rather than the deficiency of soil nutrients and the autotoxicity of allelochemicals in root exudates. The results in this study could provide the theoretical basis to explore the underlying mechanism of replanting disease of P. heterophylla and its biocontrol strategies.

  5. The allelopathic effects of invasive plant Solidago canadensis on seed germination and growth of Lactuca sativa enhanced by different types of acid deposition.

    Science.gov (United States)

    Wang, Congyan; Xiao, Hongguang; Zhao, Lulu; Liu, Jun; Wang, Lei; Zhang, Fei; Shi, Yanchun; Du, Daolin

    2016-04-01

    Invasive species can exhibit allelopathic effects on native species. Meanwhile, the types of acid deposition are gradually changing. Thus, the allelopathic effects of invasive species on seed germination and growth of native species may be altered or even enhanced under conditions with diversified acid deposition. This study aims to assess the allelopathic effects (using leaves extracts) of invasive plant Solidago canadensis on seed germination and growth of native species Lactuca sativa treated with five types of acid deposition with different SO4(2-) to NO3(-) ratios (1:0, sulfuric acid; 5:1, sulfuric-rich acid; 1:1, mixed acid; 1:5, nitric-rich acid; 0:1, nitric acid). Solidago canadensis leaf extracts exhibited significantly allelopathic effects on germination index, vigor index, and germination rate index of L. sativa. High concentration of S. canadensis leaf extracts also similarly exhibited significantly allelopathic effects on root length of L. sativa. This may be due to that S. canadensis could release allelochemicals and then trigger allelopathic effects on seed germination and growth of L. sativa. Acid deposition exhibited significantly negative effects on seedling biomass, root length, seedling height, germination index, vigor index, and germination rate index of L. sativa. This may be ascribed to the decreased soil pH values mediated by acid deposition which could produce toxic effects on seedling growth. Sulfuric acid deposition triggered more toxic effects on seedling biomass and vigor index of L. sativa than nitric acid deposition. This may be attributing to the difference in exchange capacity with hydroxyl groups (OH(-)) between SO4(2-) and NO3(-) as well as the fertilizing effects mediated by nitric deposition. All types of acid deposition significantly enhanced the allelopathic effects of S. canadensis on root length, germination index, vigor index, and germination rate index of L. sativa. This may be due to the negatively synergistic effects of

  6. Aspects of the ecology of mat-forming lichens

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    P. D. Crittenden

    2000-03-01

    Full Text Available Lichen species in the genera Cladonia (subgenus Cladina, Cetraria, Stereocaulon and Alectoria are important vegetation components on well-drained terrain and on elevated micro-sites in peatlands in boreal-Arctic regions. These lichens often form closed mats, the component thalli in which grow vertically upwards at the apices and die off in the older basal regions; they are therefore only loosely attached to the underlying soil. This growth habit is relatively unusual in lichens being found in <0.5% of known species. It might facilitate internal nutrienr recycling and higher growth rates and, together with the production of allelochemicals, it might underlie the considerable ecological success of mat-forming lichens; experiments to critically assess the importance of these processes are required. Mat-forming lichens can constitute in excess of 60% of the winter food intake of caribou and reindeer. Accordingly there is a pressing need for data on lichen growth rates, measured as mass increment, in order to help determine the carrying capacity of winter ranges for rhese herbivores and to better predict recovery rates following grazing. Trampling during the snow-free season fragments lichen thalli; mat-forming lichens regenerate very successfully from thallus fragments provided trampling does nor re-occur. Frequent recurrence of trampling creates disturbed habitats from which lichens will rapidly become eliminated consistent with J.P. Grime's CSR strategy theory. Such damage to lichen ground cover has occurred where reindeer or caribou are unable to migrate away from their winter range such as on small islands or where political boundaries have been fenced; it can also occur on summer range that contains a significant lichen component and on winter range where numbers of migrarory animals become excessive. Species of Stereocaulon, and other genera that contain cyanobacteria (most notably Peltigera and Nephroma, are among the principal agents of

  7. Photosynthetic electron-transfer reactions in the gametophyte of Pteris multifida reveal the presence of allelopathic interference from the invasive plant species Bidens pilosa.

    Science.gov (United States)

    Zhang, Kai-Mei; Shen, Yu; Zhou, Xiao-Qi; Fang, Yan-Ming; Liu, Ying; Ma, Lena Q

    2016-05-01

    To date, the response of the fern gametophyte to its environment has received considerable attention. However, studies on the influence of plant invasion on the fern gametophyte are fewer. Allelopathy has been hypothesized to play an important role in biological invasion. Hence, it is necessary to study the allelopathy of invasive plant species to the fern gametophyte and elucidate the mechanisms by which invasive plants cause phytotoxicity. As one of the main invasive plants in China, Bidens pilosa exhibits allelopathic effects on the gametophytic growth of Pteris multifida. The root exudate plays an important role among various allelochemical delivery mechanisms in B. pilosa. The effect invasive plant species has on photosynthesis in native species is poorly understood. To elucidate this effect, the changes in photosynthesis in the gametophytes of P. multifida are analyzed to examine the mechanisms of the root exudates of B. pilosa. Meanwhile, a non-invasive plant, Coreopsis basalis, was also applied to investigate the effects on fluorescence and pigments in P. multifida gametophytes. We found that gametophytes exposed to both B. pilosa and C. basalis had decreased fluorescence parameters in comparison with the control, except for non-photochemical quenching. Furthermore, it was found that these parameters were markedly affected from day 2 to day 10 in the presence of both exudates at a concentration of 25% or above. B. pilosa exudate had a negative dose-dependent effect on chlorophyll a, chlorophyll b, carotenoid, and the total chlorophyll in the gametophyte. The inhibitory effects increased with increasing exudate concentrations of both species, exhibiting the greatest inhibition at day 10. In conclusion, B. pilosa irreversibly affected the photosynthesis of P. multifida on both PS I and PS II. Root exudates caused the primary damage with respect to the decrease of the acceptors and donors of photon and electron in photosynthetic units and the production and

  8. Germinação de sementes e crescimento de plântulas de soja (Glycine max L. Merrill sob cobertura vegetal = Soybean (Glycine max L. Merrill seed germination and plantlet growth under vegetation cover

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    Lúcia Helena Pereira Nóbrega

    2009-07-01

    Full Text Available A eficiência do sistema de rotação de cultura requer, entre outrostratamentos, a escolha adequada das espécies a serem instaladas. Culturas vegetais podem apresentar compostos aleloquímicos, os quais são liberados por meio de pelos radiculares, sementes, raízes, colmos e folhas, em quantidades variáveis, capazes de interferir nas culturas subsequentes, comprometendo a produção. Assim, este estudoanalisou o potencial alelopático de aveia-preta (Avena strigosa Schreb (AP, nabo forrageiro (Raphanus sativus L. (NF, ervilhaca (Vicia sativa L. (ER, azevém (Lolium multiflorum Lam. (AZ e consórcio (CO - AP+ER+NF na germinação de sementes e crescimento de plântulas de soja. O experimento foi em laboratório, com substrato deareia, onde foram cultivadas plantas de cobertura, por 30 dias, mantendo os restos radiculares das plantas com e sem restos de parte aérea. Observou-se redução na emergência de plântulas de soja sob CO, AZ e AP. O índice de velocidade de emergência (IVE, a porcentagem de emergência em areia (EA e a massa fresca de hipocótilo (MFH foram afetados negativamente pelas plantas de cobertura.In order to be efficient, the crop rotation system requires, among other factors, an adequate choice of species to be installed. Vegetalcultures can feature allelochemical compounds, released by root hairs, roots, stems and leaves in variable amounts, which are able to interfere on subsequent cultures, as well as cause a delay in their production. Thus, this study analyzed the allelopathic potentialof black oat (Avena strigosa Schreb (BO, forage turnip (Raphanus sativus L. (FT, vetch (Vicia sativa L. (V, ryegrass (Lolium multiflorum Lam. (RG and consortium (CO - BO+V+FT on soybean seed germination and plantlet growth. This trial was carried out in a laboratory, with sand substrate, where coverage plants were grown, during 30 days. The remaining root portions of plants were kept with and without the remaining aerial part portions

  9. Allelopathic evidence in Brachiaria decumbens and its potential to invade the Brazilian Cerrados

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    Elizabeth Gorgone Barbosa

    2008-08-01

    Full Text Available The aim of this study was to look for evidence of allelochemicals in B. decumbens, in parts of the plant from where they could easily be released to the environment. The germination inhibition of Phalaris canariensis, Lactuca sativa (standard species and Melinis minutiflora, another invasive African grass, was tested using B. decumbens germinating seeds and aqueous leachates of the roots, green and senescent leaves, at 5, 10 and 20% w/v. Both the germinating seeds and the aqueous leachates of B. decumbens reduced the germination of the species tested; the effectiveness of the aqueous leachates increased according to concentration. Apparently, the competitive advantage of B. decumbens in the cerrados could be amplified via allelopathy.Invasão biológica é uma das maiores causas atuais da perda de biodiversidade. Várias espécies que se tornam invasoras produzem substâncias fitotóxicas que aumentam sua capacidade competitiva; assim, a alelopatia é uma estratégia capaz de potencializar o sucesso de invasão. Brachiaria decumbens, uma gramínea africana, invadiu os cerrados brasileiros e representa, atualmente, uma séria ameaça à biota regional. Neste ensaio, verificamos a presença de aleloquímicos em partes de B. decumbens das quais poderiam ser facilmente liberados para o ambiente. Testamos a inibição da germinação de Phalaris canariensis, Lactuca sativa (espécies padrão e Melinis minutiflora (outra gramínea africana invasora usando sementes de B. decumbens e soluções aquosas lixiviadas de suas raízes, folhas verdes e folhas senescentes, a 5, 10 e 20% de peso do material por volume de água. Tanto as sementes como as soluções lixiviadas de decumbens reduziram a germinação das outras espécies; a eficiência dos lixiviados aumentou de acordo com a concentração da solução. Acreditamos que a grande vantagem competitiva de B. decumbens no cerrado possa ser amplificada pela alelopatia.

  10. Seleção para alto teor de acilaçúcares em genótipos de tomateiro e sua relação com a resistência ao ácaro vermelho (Tetranychus evansi e à traça (Tuta absoluta Selection towards high acylsugar levels in tomato genotypes and its relationship with resistance to spider mite (Tetranychus evansi and to the South American pinworm (Tuta absoluta

    Directory of Open Access Journals (Sweden)

    Guilherme Victor Nippes Pereira

    2008-06-01

    Full Text Available Uma das estratégias do melhoramento do tomateiro, no Brasil, visando à resistência a pragas, tem sido a utilização de aleloquímicos presentes nos folíolos. Objetivou-se no presente trabalho, estudar os níveis de resistência a dois artrópodos-pragas [traça do tomateiro (Tuta absoluta e ácaros (Tetranychus evansi], em genótipos previamente selecionados com base apenas no seu teor foliar de acilaçúcares. Foram selecionadas 11 plantas contrastantes quanto aos níveis de acilaçúcares nos folíolos, de uma população F3RC2, derivada do cruzamento interespecífico Lycopersicon esculentum Mill 'TOM-584' x Lycopersicon pennellii (Correll D'Arcy 'LA-716'. Esses genótipos, juntamente com os genitores TOM-584 e LA-716, foram submetidos a ensaios de repelência/resistência a artrópodos-pragas. No teste de repelência ao ácaro T. evansi, as plantas com altos teores de acilaçúcares se comportaram de forma semelhante ao genitor resistente LA-716. As magnitudes das correlações foram negativas e significativas, confirmando assim a associação entre altos teores do aleloquímico e a resistência (repelência ao ácaro, avaliada pela distância percorrida. No ensaio realizado com a traça do tomateiro, os genótipos foram avaliados para danos nas plantas e lesões nos folíolos. Os genótipos contendo alto teor de acilaçúcares, demonstraram bons níveis de resistência a Tuta absoluta, não diferindo significativamente do acesso selvagem LA-716. Em todas as épocas de avaliação, os teores de acilaçúcares mostraram-se alta e negativamente correlacionados com os níveis de dano causados pela traça. Os resultados obtidos comprovaram a eficiência da seleção de genótipos de tomateiro com elevados teores de acilaçúcares nos folíolos, visando à resistência a artrópodos-praga.Selection for high foliar levels of allelochemicals has been proposed as a suitable strategy for breeding tomatoes for arthropod pest resistance. In the

  11. Hosting Capacity of Horticultural Plants for Insect Pests in Brazil Capacidad de Alojamiento de Plantas Hortícolas para Plagas de Insectos en Brasil

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    Germano L.D Leite

    2011-09-01

    Full Text Available Factors such as fertilization, allelochemicals, trichomes, weather, and natural enemies can influence pest populations. Thus, it is necessary to understand the factors that predispose vegetable species to pests and the role of polyculture, crop rotation, and neighboring plants. The objective of this research was to study the hosting capacity for pests of Abelmoschus esculentus (L., Brassica oleracea L. vars. acephala and capitata, Capsicum annuum L., Cucurbita moschata (Duchesne, Cucurbita maxima Duchesne and Cucumis sativus L., Lycopersicon esculentum Mill., Solanum gilo Raddi and Solanum melongena L., and Phaseolus vulgaris L. The higher density of Bemisia tabaci (Genn. adults on C. sativus can be due to the higher amount of pentacosane and octacosane in this plant. The occurrence of Brevicoryne brassicae (L. only in Brassica spp. can be accounted for by the nonacosane of these plants. The low trichome density and greater palmitic acid level can explain the greatest damage by Aphis gossypii Glover in A. esculentum. Empoasca sp. was more frequent in P. vulgaris followed by A. esculentum, which are plants with lower K content. Solanum melongena was attacked more by Hydrangea similis (Walker and Epitrix sp. perhaps because of higher palmitic acid and 11,14,17-eicosatrienoic methyl ester concentrations in their leaves. Frankliniella sp. exhibited more damage in C. sativus probably owing to higher pentacosane and octacosane in its leaves. Sistena sp. was more frequent in C. maxima and had higher octadecane levels and trichome density. The presence of ¥-humulene and hexacosane can explain the damage by Tuta absoluta (Meyrick on L. esculentum.Factores tales como la fertilización, aleloquímicos, tricomas, el clima y los enemigos naturales pueden influir en las poblaciones de plagas. Por lo tanto, es necesario comprender los factores que predisponen a las especies vegetales a las plagas y el papel de policultivos, rotación de cultivos y las plantas

  12. Behaviour and chemical ecology of Bactrocera flies

    International Nuclear Information System (INIS)

    Tan, Keng-Hong

    2000-01-01

    . Semiochemicals are divided into ecomone and para-ecomone, the former is released naturally into the environment, the latter is not. An ecomone with intraspecies activity is known as a pheromone. One with interspecies activity is generally grouped under allelochemicals. It is specifically known as: 1) an allomone when it benefits the releaser with detrimental effect on the receiver, 2) a kairomone when it benefits the receiver with detrimental effect on the releaser, 3) a synomone when it benefits both the releaser and receiver, or 4) an apneumone when released from dead or decaying material caused by microbial action. A para-ecomone may be either a constituent of an organism or a synthetic chemical not released naturally. It should be emphasised that a chemical can be an ecomone and a para-ecomone and, as an ecomone, may act as a pheromone as well as an allomone or a kairomone. The study of an organism's ecomone in relation to the environment, interaction between individuals belonging to the same and/or different species, and how it affects behaviour constitutes the bulk of chemical ecology. Ecomones in applied entomology may be exploited as agents for 1) insect pest surveillance and monitoring, 2) trapping insect in population estimation or as an intervention technique such as the area-wide male annihilation technique, and 3) understanding and disrupting insect communication in a pest control or management programme. This paper presents an update of the behaviour within the context of chemical ecology of Bactrocera flies which is crucial in the understanding the flies' role in the complex communal interrelationships within Malaysian agro- and natural ecosystems as previously presented (Tan 1993)

  13. Estudo fitoquímico de Senna alata por duas metodologias Phytochemical study of Senna alata using two methodologies

    Directory of Open Access Journals (Sweden)

    I.M.C. Rodrigues

    2009-01-01

    determine the main classes of potential allelochemicals of different fractions (stems, flowers, leaves, roots, seeds and pods of S. alata. The plant material was dried and submitted to exhaustive extraction with hydromethanolic solvent to obtain the crude extracts, with a small part being solubilized in methanol to obtain the test solutions. The following methods were used: thin-layer chromatography (TLC, to determine the qualitative chromatographic profile, and preliminary detection tests of the distinct chemical constituents, based on their extraction with appropriate solvents and application of color testing. The results of both methods showed few similarities, with the TLC being the simplest, most inexpensive, fastest, and most appropriate for preliminary analysis of plant-derived chemical compounds, despite being a qualitative method. This method was more sensitive for flavonoid detection, although the Bouchardat reactive was more sensitive to alkaloid detection than the Dragendorff. Ammonium hydroxide 10% was more sensitive to anthraquinones than Potassium hydroxide. The study showed the high diversity of the chemical compounds present in Senna alata, justifying its extensive use in popular medicine and even indicating its potential allelopathic use.

  14. Seleção indireta para teor de 2-tridecanona em tomateiros segregantes e sua relação com a resistência à traça-do-tomateiro Indirect selection to 2-tridecanone content and its relation to tomato pinworm resistance

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    Cláudia Regina Gontijo Labory

    1999-05-01

    Full Text Available Este trabalho teve como objetivo verificar a relação entre o teor de 2-tridecanona (2-TD em materiais selecionados e o nível de resistência à traça-do-tomateiro (Tuta absoluta (Meyrick, 1917 (Lepidoptera: Gelechiidae em gerações avançadas de Lycopersicon spp. derivado de cruzamentos interespecíficos. Foi usada uma população de tomateiros segregantes (geração F4RC2 para 2-TD, uma metilcetona que confere resistência à traça-do-tomateiro. Genótipos foram selecionados e avaliados quanto à resistência do tipo não-preferência: três materiais com alto teor do aleloquímico 2-TD (HI1, HI2, HI3 e dois materiais com baixo teor (LO1, LO2, além das testemunhas. Após infestação controlada, foram avaliados: contagem do número de ovos postos, evolução da lesão nos folíolos, porcentagem de folíolos atacados, e índice geral de lesão causada pela traça. Plantas com alto teor de 2-TD (HI1 e HI3 tiveram uma baixa progressão das lesões ocasionadas pelo ataque de T. absoluta. A planta LO1 foi muito atacada pela praga, o mesmo não ocorrendo com a planta LO2, que foi infestada acidentalmente por ácaros do gênero Tetranychus, acarretando, provavelmente, uma disputa de nicho ecológico entre os dois artrópodes. Concluiu-se que altos teores de 2-TD estão ligados a mecanismos de resistência à traça-do-tomateiro do tipo não-preferência por oviposição e alimentação.This work had the objective to verify the relation between 2-tridecanone (2-TD in selected plants and resistance level to tomato pinworm (Tutaabsoluta (Meyrick, 1917 (Lepidoptera: Gelechiidae in advanced generations of Lycopersicon spp. interspecific crosses. It was used a tomato population (F4RC2 generation segregant for 2-TD, a methyl ketone that controls the resistance of the tomato pinworm. Materials were selected and evaluated for a non-preference mechanism of resistance. Three genotypes with high level of the allelochemic 2-TD (HI1, HI2, HI3, two with low

  15. Phytotoxicity of the extracts of Lonchocarpus muehlbergianus Hassl. (Fabaceae leaflets and galls on seed germination and early development of lettuce Fitotoxidade diferencial dos extratos aquosos de folíolos e galhas de Lonchocarpus muelhbergianus Hassl. (Fabaceae na germinação e desenvolvimento inicial de alface

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    Denis Coelho de Oliveira

    2008-12-01

    Full Text Available Galls induced by Euphalerus ostreoides (Hemiptera: Psyllidae cause structural and chemical alterations on Lonchocarpus muehlbergianus leaflets. Healthy and galled leaflet tissues of this plant species are rich in secondary metabolites with potential allelopathic effects. This research compares the allelopathic effects of the aqueous extracts of L. muehlbergianus leaflets and galls on seeds and seedlings of Lactuta sativa, and evaluates the chemical impact produced by a gall-inducing insect on the other trophic levels associated with it. The extracts were obtained through static maceration in distilled water (5% p/v. The treatments consisted of aqueous crude extracts and those previously filtered in polyvinylpirrolidone (PVP. After seven days, seedling height was measured, and the radicles were fixed in FAA50 for anatomical analyses. Healthy leaflet and gall aqueous extracts, and those filtered in PVP, significantly inhibited seed germination, with no significant differences between the two groups. Treatments with aqueous extracts reduced seed germination speed and vegetative axis length. Plant tissue alterations confirm the phytotoxicity of allelochemical substances present in the extracts. The differences among the treatments indicated that gall formation altered L. muehlbergianus leaflet metabolism, and this could influence the other trophic levels associated with this gall inducing-host plant system.Galhas induzidas por Euphalerus ostreoides (Hemiptera: Psyllidae produzem alterações estruturais e químicas nos folíolos de Lonchocarpus muehlbergianus. As galhas, em geral, atuam como drenos de fotoassimilados podendo acumular tanto compostos do metabolismo primário, associados à alimentação do inseto quanto do metabolismo secundário, relacionados às inter-relações da planta-hospedeira com o galhador e demais níveis tróficos associados. Tecidos sadios e galhados de L. muehlbergianus são ricos em metabólitos com efeito alelop

  16. Allelopathic Effect of Wheat and Barley Residues on Yield and Yield Components of Cowpea (Vigna sinensis L. and Weeds Control

    Directory of Open Access Journals (Sweden)

    M Shahbyki

    2018-02-01

    residue at a rate of 4 and 8 ton ha-1 significantly decreased weed density than non-weeding treatment. Seed number per pod, biological and grain yield of cowpea significantly increased in the soil incorporation with wheat residue at a rate of 8 ton ha-1 compared to control. Our results showed that weeding and soil incorporation with wheat residue at a rate of 8 ton ha-1 increased cowpea yield by 78.23 and 80.79% compared to no weeding treatment, respectively. Wheat is a potent source of bioactive phytotoxic compounds representing three main classes as phenolic (hydroxybenzoic, vanillic, pcoumaric, syringic and ferulic acids being most frequently reported and transferulic and trans-pcoumaric acids being the dominant acids, cyclic hydroxamic acids (a class of alkaloids and short chain fatty acids. It is reported that wheat extract compounds can interfere with basic processes of receiver plants as photosynthesis, cell division, respiration and protein synthesis and indirectly provoke other forms of stresses. Thus, these compounds can reduce weed germination and growth. Another important effect of these allelochemicals is the activation of cellular antioxidant system in response to uncontrolled production and accumulation of reactive oxygen species. The reason for increase in grain yield was the control of weeds and probably the allelopathic effects of crop water extracts promoted the wheat growth which ultimately increases grain yield. Conclusions The present study concluded that wheat phytotoxins in straw inhibited germination and seedling growth of weeds, and the inhibition was concentration-dependent. Also wheat straw added to soil increased yield and some traits of cowpea. In general, the results showed that wheat straw can reduce weed suppression and can improve characteristics of plant, moreover, decreased environment risks of chemical inputs and ensure sustainability of production in long time.

  17. Diferenças no padrão da atividade alelopática em espécies da família Leguminosae Differences in allelopathic activity patterns in Leguminosae

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    M. Mourão Júnior

    2010-01-01

    plant sensitivity. Bio assays of seed germination and radicle and hypocotyl elongation were developed under controlled conditions. The results indicated that the species studied do not present a similar pattern regarding the potential allelopathic effects; however, there is a hierarchy concerning the intensity of the global effects, with the allelopathic inhibitory potential being more extensive and effective for the species Bauhinia guianensis, Bowdichia virgiloides, Parkia pendula and Platimenia reticulate, and more restricted and effective for Bauhinia macrostachya. The plant fraction factor showed differences in the activity pattern, with the leaves being the main source of allelochemicals for most species, and the roots, for Bauhinia macrostachya and Inga edulis. In terms of response pattern of the receptor plants, radicle elongation is more sensitive to the effects of the extracts, with hypocotyl elongation being the least sensitive. The effect of the extracts was more intense for Mimosa pudica. These results confirm the importance of the Amazon forest as a source of chemical compounds of interest to mankind, which by itself justifies its preservation.

  18. Substâncias químicas com atividades alelopáticas presentes nas folhas de Parkia pendula (Leguminosae Chemical compounds with allelopathic activities in Parkia pendula (Leguminosae leaves

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    A.P.S. Souza Filho

    2005-12-01

    under controlled conditions of 25 ºC of temperature and 12-hour photoperiod for seed germination and 24-hour photoperiod for radicle elongation. The following allelochemicals were isolated and identified in P. pendula's leaves: 3,4,5-trimethoxybenzoic acid (S1, 3,4-dimethoxybenzoic acid (S2 and Blumenol A (S3. Comparatively, S1 and S2 showed greater allelopathic activity. The effects on radicle elongation were greater than those observed on seed germination. The isolated substances showed low inhibition potential on seed germination, especially on S. obtusifolia seeds. The allopathic inhibition effects were positively related to the concentration of the substances, although in some cases, these effects have not corresponded to the statistical differences.