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

BARBOSA, Elizabeth Gorgone; PIVELLO, Vânia Regina; MEIRELLES, Sérgio Tadeu
Fonte: Tecpar Publicador: Tecpar
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
27.01%
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...

Determination of polyamines in organic extracts from roots of Canavalia ensiformis by capillary electrophoresis

SANTOS, S.; MORAES, M. L. L.; REZENDE, M. O. O.
Fonte: TAYLOR & FRANCIS INC Publicador: TAYLOR & FRANCIS INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
27.01%
A rapid, selective and specific capillary zone electrophoresis method to determine polyamines in organic extracts from roots of Canavalia ensiformis (Jack Beans) was developed using ultra violet (UV) detection. Canavalia ensiformis is relatively free from diseases and it is used as reference in allelopathy studies. Polyamines are widely distributed in plant and it could be involved in plant pathogen interactions. Optimal separation was achieved using 15 mmol.L-1formic acid (pH 3.0) + 4 mmol.L-1 imidazole as a background electrolyte. It was possible to identify and quantify the polyamines on herbal samples in the presence of other phytochemical substances and analyze them quickly (up to 6 min). The applicability of this method was evaluated in crude organic extracts from roots of Canavalia ensiformis.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP Fundacao de Amparo a Pesquisa do Estado de Sao Paulo; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); CAPES Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fate of allelochemicals in the soil; Fate of allelochemicals in the soil

Vidal, Ribas Antonio; Bauman, Thomas Trost
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
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Aleloquímicos são compostos liberados por plantas ou seus resíduos e que podem ter efeito negativo ou positivo em outra planta. A importância da alelopatia foi estudada intensamente nas últimas três décadas, sendo que a maioria dos trabalhos abordou a extração e identificação dos compostos e, demonstração de seus efeitos em experimentos realizados em placas de petri. Estes químicos interagem no ambiente assim como os herbicidas e estão sujeitos aos processos de degradação por decomposição microbiana, fotólise e oxidação e, processos de remoção ou transferência como volatilização e adsorção. O objetivo desta revisão de literatura foi estudar o destino de aleloquímicos no ambiente para auxiliar na definição de estratégias para aumentar sua atividade. A atividade dos aleloquímicos é limitada pelo tempo (devido a liberação lenta do material doador) e pelo espaço (devido à interação com o ambiente). Demonstrações de alelopatia devem incluir o destino no ambiente do composto envolvido, apresentando estudos de processos de degradação e remoção.; Allelochemicals are compounds released by one plant or plant residues that may have a negative or positive effect on other plant. The importance of allelopathy was extensively explored during the past three decades...

Allelopathy and phytotoxicity of Zanthoxylum rhoifolium Lam.

Silva, R. M. G.; Livio, A. A.; Santos, V. H. M.; Mecina, G. F.; Silva, L. P.
Fonte: Allelopathy Journal Publicador: Allelopathy Journal
Tipo: Artigo de Revista Científica Formato: 221-233
ENG
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37.29%
In Cerrado, Zanthoxylum rhoifolium Lam. stands out because it interferes with the growth and development of other plants. The preliminary phytochemical analyses showed the presence of polyphenols and flavonoids. The Z. rhoifolium extract inhibited the germination index (5 mg mL(-1)=0.5%; 10mg mL(-1)=37.(5%) and 20mg mL(-1)=85.5%) decreased the germination and the lettuce seedlings growth (roots and the hypocotyls) and reduced the mitotic index than control. The extract of 1000 mu g mL(-1)conc contained (165.20 mg and 45.74 mg, phenols and total flavonoids, respectively) and had higher antioxidant activity (80.52%). We concluded that Z. rhofolium possesses allelopathic potential.

Research on allelopathy in Portugal

Dias, L.S.; Pereira, I.P.; Dias, A.S.
Fonte: Science Publishers, Inc. Publicador: Science Publishers, Inc.
Tipo: Parte de Livro Formato: 6343 bytes; application/pdf
ENG
Relevância na Pesquisa
37.47%
The review shows that allelopathy is widespread in shrubs and trees of Portugal and hence, may play an important role in their ecology. The role of soil in the nature and intensity of allelopathy was demonstrated, and the potential of wheat straw and some aromatic plants to provide allelochemicals for herbicidal use has been found. Therefore, future lines of research should include I) the investigation of herbicidal potential of allelochemicals already identified in wheat straw, II) screening of more plant species as potential sources of allelochemicals and III) use of more more weed species as test species. If feasible, soil should be used in allelopathic studies.

Allelopathic effects of Raphanus raphanistrum and interactions of effects on wheat and oat

Dias, L.S.; Dias, A.S.
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
27.29%
Raphanus raphanistrum L. (wild radish) is an important weed of grain crops worldwide. Allelopathic activity against several species has been reported in association with wild radish shoots and wild radish-amended soils. Therefore, assuming that allelopathy is an important and primary trait of wild radish weediness, two hypotheses can be derived: 1) high levels of phytoactivity of wild radish against crops where it ranks high as a weed are to be expected and 2) synergy of effects between compounds extracted from leaves and stems should also be widespread given the advantage provided by the lesser investment needed to attain the same result. Wild radish leaves (L), stems (S), and leaves plus stems (LS) were grounded, extracted with distilled water and bioassayed in wheat and oat germination and early growth to test these hypotheses. In wheat, germination was reduced by the three extracts, root growth by L- and LS-extract, leaf growth was unaffected, and leaf/root length ratio increased by S- and LS-extract. In oat, germination was unaffected, root growth reduced by the three extracts, leaf growth was unaffected, and leaf/root length ratio increased by the three extracts. Germination is only reduced in wheat, by as much as 61%, while early root growth of wheat and oat is strongly reduced by as much as 76% in wheat and 81% in oat...

Allelopathic research in Brazil

Reigosa,Manuel; Gomes,Anabele Stefânia; Ferreira,Alfredo Gui; Borghetti,Fabian
Fonte: Sociedade Botânica do Brasil Publicador: Sociedade Botânica do Brasil
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
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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.

Fate of allelochemicals in the soil

Vidal,Ribas Antonio; Bauman,Thomas Trost
Fonte: Universidade Federal de Santa Maria Publicador: Universidade Federal de Santa Maria
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/1997 EN
Relevância na Pesquisa
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Allelochemicals are compounds released by one plant or plant residues that may have a negative or positive effect on other plant. The importance of allelopathy was extensively explored during the past three decades, with the work concentrating in the extraction and identification of the chemicals, and demonstration of activity in petry dish experiments. These compounds interact in the soil environment similarly as herbicides and are subject to processes of degradation such as microbial degradation, oxidation, and photolysis, and processes of removal or transfer, such as volatilization and adsorption. The objective of this review was to access the fate of allelochemicals in the soil environment to help to find strategies to increase its activity. The activity of allelochemical is limited in time (because of slow release from the donor material) and in space (because of the interaction with the environment). Demonstration of allelopathy should include the fate of the proposed chemical in the soil environment, presenting studies of degradation and removal processes.

Competing phytoplankton undermines allelopathy of a bloom-forming dinoflagellate

Prince, Emily K; Myers, Tracey L; Naar, Jerome; Kubanek, Julia
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.74%
Biotic interactions in the plankton can be both complex and dynamic. Competition among phytoplankton is often chemically mediated, but no studies have considered whether allelopathic compounds are modified by biotic interactions. Here, we show that compounds exuded during Karenia brevis blooms were allelopathic to the cosmopolitan diatom Skeletonema costatum, but that bloom allelopathy varied dramatically among collections and years. We investigated several possible causes of this variability and found that neither bloom density nor concentrations of water-borne brevetoxins correlated with allelopathic potency. However, when we directly tested whether the presence of competing phytoplankton influenced bloom allelopathy, we found that S. costatum reduced the growth-inhibiting effects of bloom exudates, suggesting that S. costatum has a mechanism for undermining K. brevis allelopathy. Additional laboratory experiments indicated that inducible changes to K. brevis allelopathy were restricted to two diatoms among five sensitive phytoplankton species, whereas five other species were constitutively resistant to K. brevis allelopathy. Our results suggest that competitors differ in their responses to phytoplankton allelopathy, with S. costatum exhibiting a previously undescribed method of resistance that may influence community structure and alter bloom dynamics.

Dose-Response—A Challenge for Allelopathy?

Belz, Regina G.; Hurle, Karl; Duke, Stephen O.
Fonte: International Hormesis Society Publicador: International Hormesis Society
Tipo: Artigo de Revista Científica
Publicado em /04/2005 EN
Relevância na Pesquisa
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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....

Mathematical Modelling of Allelopathy: IV. Assessment of Contributions of Competition and Allelopathy to Interference by Barley

Liu, De Li; An, Min; Johnson, I.R.; Lovett, J.V.
Fonte: International Hormesis Society Publicador: International Hormesis Society
Tipo: Artigo de Revista Científica
Publicado em /04/2005 EN
Relevância na Pesquisa
27.74%
One of the main challenges to the research on allelopathy is technically the separation of allelopathic effect from competition, and quantitatively, the assessment of the contribution of each component to overall interference. A simple mathematical model is proposed to calculate the contribution of allelopathy and competition to interference. As an example of applying the quantitative model to interference by barley (Hordeum vulgare cv. Triumph), the approach used was an addition of allelopathic effect, by an equivalent amount, to the environment of the test plant (white mustard, Sinapis alba), rather than elimination of competition. Experiments were conducted in glasshouse to determine the magnitude of the contributions of allelopathy and competition to interference by barley. The leachates of living barley roots significantly reduced the total dry weight of white mustard. The model involved the calculation of adjusted densities to an equivalent basis for modelling the contribution of allelopathy and competition to total interference. The results showed that allelopathy contributed 40%, 37% and 43% to interference by barley at 6, 12 and 18 white mustard pot−1. The consistency in magnitude of the calculated contribution of allelopathic effect by barley across various densities of receiver plant suggested that the adjusted equivalent density is effective and that the model is able to assess the contribution of each component of interference regardless of the density of receiver plant.

To survive or to slay: Resource-foraging role of metabolites implicated in allelopathy

Tharayil, Nishanth
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
Publicado em /07/2009 EN
Relevância na Pesquisa
27.29%
The ecological relevance of allelopathy is highly debated due to the lack of phytotoxic concentrations of allelochemical in natural field conditions. Most of the putative allelochemicals are exuded at low concentrations, and subsequently undergo rapid chemical and biological degradation in soil matrices. At sub-toxic concentrations, due to hormesis effect, these compounds could possibly have a stimulatory effect on plant growth. Many of the suggested allelopathic compounds are chelants and can complex-with and mobilize metal ions in soil. These complexation reactions will detoxify the compound, but will increase the chemical-nutrient-foraging ability of the donor plant. The concentration in which these compounds are exuded matches with other similar secondary metabolites facilitating plant nutrient acquisition. Irrespective of whether the implicated PSMs facilitate donor plant in chemical nutrient-foraging or in poisoning the neighbors, the conferred advantage translates in terms of resource availability—in first case the donor enjoys uncontested nutrient uptake efficiency, where as in the latter the donor gain an uncontested access to resources. This further reaffirms the notion that resource competition and allelopathy are inextricable. Since most of the secondary metabolites could mobilize nutrients from soil...

Genetic evidence for natural product mediated plant–plant allelopathy in rice

Xu, Meimei; Galhano, Rita; Wiemann, Philipp; Bueno, Emilio; Tiernan, Mollie; Wu, William; Chung, Ill-Min; Gershenzon, Jonathan; Tudzynski, Bettina; Sesma, Ane; Peters, Reuben J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
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A role for specific natural products in directly mediating antagonistic plant–plant interactions –that is, allelopathy –has been controversial. If proven, such phenomena would hold considerable promise for agronomic improvement of staple food crops such as rice (Oryza sativa).However, while substantiated by the presence of phytotoxic compounds at potentially relevant levels, demonstrating a direct role for specific natural products in allelopathy has been difficult due to the chemical complexity of root and plant litter exudates. This complexity can be bypassed via selective genetic manipulation to ablate production of putative allelopathic compounds, but such an approach previously has not been applied.The rice diterpenoid momilactones provide an example of natural products for which correlative biochemical evidence has been obtained for a role in allelopathy. Here, we apply reverse genetics, using knock-outs of the relevant diterpene synthases (OsCPS4 and OsKSL4), to demonstrate that rice momilactones are involved in allelopathy, including suppressing growth of the widespread rice paddy weed, barnyard grass (Echinochloa crus-galli).Thus, our results not only provide novel genetic evidence for natural product mediated allelopathy...

Separation of Allelopathy from Resource Competition Using Rice/Barnyardgrass Mixed-Cultures

He, Hai Bin; Wang, Hai Bin; Fang, Chang Xun; Lin, Zhi Hua; Yu, Zheng Ming; Lin, Wen Xiong
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 10/05/2012 EN
Relevância na Pesquisa
27.59%
Plant-plant interference is the combined effect of allelopathy, resource competition, and many other factors. Separating allelopathy from resource competition is almost impossible in natural systems but it is important to evaluate the relative contribution of each of the two mechanisms on plant interference. Research on allelopathy in natural and cultivated plant communities has been hindered in the absence of a reliable method that can separate allelopathic effect from resource competition. In this paper, the interactions between allelopathic rice accession PI312777, non-allelopathic rice accession Lemont and barnyardgrass were explored respectively by using a target (rice)-neighbor (barnyardgrass) mixed-culture in hydroponic system. The relative competitive intensity (RCI), the relative neighbor effect (RNE) and the competitive ratio (CR) were used to quantify the intensity of competition between each of the two different potentially allelopathic rice accessions and barnyardgrass. Use of hydroponic culture system enabled us to exclude any uncontrolled factors that might operate in the soil and we were able to separate allelopathy from resource competition between each rice accession and barnyardgrass. The RCI and RNE values showed that the plant-plant interaction was positive (facilitation) for PI312777 but that was negative (competition) for Lemont and barnyardgrass in rice/barnyardgrass mixed-cultures. The CR values showed that one PI312777 plant was more competitive than 2 barnyardgrass plants. The allelopathic effects of PI312777 were much more intense than the resource competition in rice/barnyardgrass mixed cultures. The reverse was true for Lemont. These results demonstrate that the allelopathic effect of PI312777 was predominant in rice/barnyardgrass mixed-cultures. The most significant result of our study is the discovery of an experimental design...

SEAWEED ALLELOPATHY AGAINST CORAL: SURFACE DISTRIBUTION OF A SEAWEED SECONDARY METABOLITE BY IMAGING MASS SPECTROMETRY

Andras, Tiffany D.; Alexander, Troy S.; Gahlena, Asiri; Parry, R. Mitchell; Fernandez, Facundo M.; Kubanek, Julia; Wang, May D.; Hay, Mark E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.29%
Coral reefs are in global decline, with seaweeds increasing as corals decrease. Although seaweeds inhibit coral growth, recruitment, and survivorship, the mechanism of these interactions is poorly understood. Here, we used field experiments to show that contact with four common seaweeds induces bleaching on natural colonies of Porites rus. Controls in contact with inert, plastic mimics of seaweeds did not bleach, suggesting seaweed effects resulted from allelopathy rather than shading, abrasion, or physical contact. Bioassay-guided fractionation of the hydrophobic extract from the red alga Phacelocarpus neurymenioides revealed a previously characterized antibacterial metabolite, neurymenolide A, as the main allelopathic agent. For allelopathy of lipidsoluble metabolites to be effective, the compounds would need to be deployed on algal surfaces where they could transfer to corals on contact. We used desorption electrospray ionization mass spectrometry (DESI-MS) to visualize and quantify neurymenolide A on the surface of P. neurymenioides, and we found the molecule on all surfaces analyzed, with highest concentrations on basal portions of blades.

Durum wheat and allelopathy: toward wheat breeding for natural weed management

Fragasso, Mariagiovanna; Iannucci, Anna; Papa, Roberto
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 24/09/2013 EN
Relevância na Pesquisa
27.59%
Wheat-derived foodstuffs represent about one-fifth of the calories consumed by humans worldwide. Bread wheat (Triticum aestivum L.) is one of the most important crops throughout the world, and it has been extensively studied for its allelopathic potential. In contrast, for allelopathy in durum wheat (Triticum turgidum ssp. durum), our knowledge is partial and fragmentary. Through highlighting recent advances in using allelopathy as a crop-breeding tool, we provide an overview of allelopathy in Triticum spp., to stimulate further coordinated breeding-oriented studies, to favor allelopathy exploitation for the sustainable cultivation of wheat, and in particular, to achieve improved biological weed control.

Competition induces allelopathy but suppresses growth and anti-herbivore defence in a chemically rich seaweed

Rasher, Douglas B.; Hay, Mark E.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em 22/02/2014 EN
Relevância na Pesquisa
27.59%
Many seaweeds and terrestrial plants induce chemical defences in response to herbivory, but whether they induce chemical defences against competitors (allelopathy) remains poorly understood. We evaluated whether two tropical seaweeds induce allelopathy in response to competition with a reef-building coral. We also assessed the effects of competition on seaweed growth and seaweed chemical defence against herbivores. Following 8 days of competition with the coral Porites cylindrica, the chemically rich seaweed Galaxaura filamentosa induced increased allelochemicals and became nearly twice as damaging to the coral. However, it also experienced significantly reduced growth and increased palatability to herbivores (because of reduced chemical defences). Under the same conditions, the seaweed Sargassum polycystum did not induce allelopathy and did not experience a change in growth or palatability. This is the first demonstration of induced allelopathy in a seaweed, or of competitors reducing seaweed chemical defences against herbivores. Our results suggest that the chemical ecology of coral–seaweed–herbivore interactions can be complex and nuanced, highlighting the need to incorporate greater ecological complexity into the study of chemical defence.

Efeito de cascas de café e de arroz dispostas nas camadas do solo sobre a germinação e o crescimento inicial do Caruru-de-mancha; Allelopathic Effect of Coffee and Rice husks arranged in soil layers on the germination and initial growth of Amaranthus viridis

Fonte: Sociedade Brasileira da Ciência das Plantas Daninhas Publicador: Sociedade Brasileira da Ciência das Plantas Daninhas
Tipo: Artigo de Revista Científica
PT_BR
Relevância na Pesquisa
27.29%
Studies of plant residue effects involving mulches to control weeds in perennial crops are difficult to carry out due to the need to differentiate between allelopathy and competition. Many researches, nowadays, refer to criteria proving allelopathy. This work was established under greenhouse conditions to determine the allelopathic effects of coffee and rice husks on Amaranthus viridis through their arrangements in soil layers. The experimental design was a randomized block with four replications, arranged in a 3 x 3 factorial scheme, with coffee and rice husks and expanded vermiculite being one factor and their residues placed on the top and incorporated into the soil surface and into the bottom, as the other factor. One additional treatment without mulching was used. Overall, plant residues inhibited seed germination and stimulated growth of slender amaranth. Rice husk showed lower emergent velocity index and seed germination than coffee husk. Coffee husk placed on the top provided greater growth and higher dry matter weight of slender amaranth, followed by husk incorporation into the soil surface.

Toxin-allelopathy among phytoplankton species prevents competitive exclusion

Roy, Shovonlal; Chattopadhyay, Joydev
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/07/2006
Relevância na Pesquisa
27.29%
Toxic or allelopathic compounds liberated by toxin-producing phytoplankton (TPP) acts as a strong mediator in plankton dynamics. On an analysis of a set of phytoplankton biomass-data that have been collected by our group in the North-West part of the Bay of Bengal, and by analysis of a three-component mathematical model under a constant as well as a stochastic environment, we explore the role of toxin-allelopathy in determining the dynamic behaviour of the competing-phytoplankton species. The overall results, based on analytical and numerical wings, demonstrate that toxin-allelopathy due to the toxin-producing phytoplankton (TPP) promotes a stable coexistence of those competitive phytoplankton that would otherwise exhibit competitive exclusion of the weak species. Our study suggests that TPP might be a potential candidate for maintaining the coexistence and diversity of competing phytoplankton species.; Comment: 29 pages, 6 figures, Journal Paper

Flavonoids: Their Structure, Biosynthesis and Role in the Rhizosphere, Including Allelopathy

Weston , Leslie A; Mathesius, Ulrike
Fonte: Plenum Publishing Corporation Publicador: Plenum Publishing Corporation
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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Flavonoids are biologically active low molecular weight secondary metabolites that are produced by plants, with over 10,000 structural variants now reported. Due to their physical and biochemical properties, they interact with many diverse targets in subcellular locations to elicit various activities in microbes, plants, and animals. In plants, flavonoids play important roles in transport of auxin, root and shoot development, pollination, modulation of reactive oxygen species, and signalling of symbiotic bacteria in the legume Rhizobium symbiosis. In addition, they possess antibacterial, antifungal, antiviral, and anticancer activities. In the plant, flavonoids are transported within and between plant tissues and cells, and are specifically released into the rhizosphere by roots where they are involved in plant/plant interactions or allelopathy. Released by root exudation or tissue degradation over time, both aglycones and glycosides of flavonoids are found in soil solutions and root exudates. Although the relative role of flavonoids in allelopathic interference has been less well-characterized than that of some secondary metabolites, we present classic examples of their involvement in autotoxicity and allelopathy. We also describe their activity and fate in the soil rhizosphere in selected examples involving pasture legumes...