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Schematic representation of Yin/Yang theory
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Of the disciplines involved in allelopathy research, mathematical modelling is making increasingly significant contributions.
This chapter discusses, from a point of mathematical modelling view, some fundamental issues in allelopathy research, such
as hormesis phenomenon and its interpretation, function of allelopathy and its relationship with comp...
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... other, as well as coexistent. As a unity of op- posites, Yin and Yang, although separate forces, are really part of the same ultimate unity, i.e., Yin implies Yang, Yang embodies Yin, and each is, therefore, necessary to the other. It is through this interaction of these two primal forces that all of the phenomena of the universe are produced (Fig. ...
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... Reactions to allelochemicals were species-specific and depended on concentration (An et al., 2008). Species specificity to allelochemical action has also been reported by Bakhshayeshan-Agdam et al. (2015), who observed stronger resistance to the action of Amaranthus retroflexus extracts in wheat and cucumber than in common bean and alfalfa. ...
The present research study identified garden pea varieties with pronounced tolerance to the allelopatic action of Sorghum halepense. Nine varieties were selected to study the effects of shoot and root weed biomass, applied in three extract concentrations (1, 5 and 10%), on seed germination and initial germ growth. A variance analysis of data revealed significant influence (p <0.05) of three studied factors (variety, type and concentration of extracts) on the investigated parameters. Statistically insignificant was only the influence of extract type (root/aboveground biomass) on seed germination. Based on absolute values of the allelopathic indicator RI, which determines the degree of allelopathic inhibition in terms of germination, germ length and weight in different varieties, the variation was as follows: from-0.30 to-0.04, from-1.31 to-2.96 and from-0.47 to 0.02. The total effect of allelopathic action of S. halepense on all studied parameters, presented as a GGE-biplot analysis, defined Pulpudeva and Puldin varieties as exhibiting higher tolerance, in contrast to Denitsa and Vyatovo, which were sensitive. Ran I, Mira, Musala and Vechernitsa occupied an intermediate position. Cultivation of allelopathic tolerant varieties is a promising addition to the current weed control strategy, especially in organic production.
... Allelopathy has been regarded as 'novel weapons' for the successful exotic plant invasion (2,7,39,40,44). However, whether allelopathic potential of ferns plays a role in their invasion is unknown. ...
Lygodium microphyllum (Cav.) R. Br. is an invasive climbing fern weed that has become aggressive in humid habitats in tropical regions. We studied the phytotoxicity of its aqueous leachates and dried leaf litters on 3-receptor species: Festuca arundinacea Schreb, Cynodon dactylon (L.) Pers. and Sorghum sudanenses (Piper) Stapf. The aqueous leaf leachates at >= 25 mg/mL and the leaf litter leachates >= 3 mg/mL inhibited the seed germination and seedling growth of all three tested plants. The dry leaves of L. microphyllum applied at 2 t/ha dose as soil surface mulch inhibited the root growth of F. arundinacea, C. dactylon and S. sudanenses by 26.8, 29.3 and 31.7%, respectively. The chemical constituents in essential oils of microphyllum were analyzed by GC-MS. Fifteen components were identified. The main constituents were alpha-monoolein (28.3%), ethylene glycol oleate (25.7%) and undecyne (15.5%). The antimicrobial activities of essential oils were tested against 3-bacteria : Staphylococcus aureus, Escherichia coli and Piricularia oryzae Cav, by disc diffusion method. The essential oils were highly bactericidal against S. aureus, E. coli and P oryzae at 12.5 mg/mL. Both laboratory and field experiments showed that L. microphyllum was allelopathic to tested plants, and its allelopathic potential may help in understanding the invasiveness of this specie.
... All plant structures, including roots, stems, leaves, flowers, fruits, and seeds, are capable of releasing chemicals into the environment (45). Plant responses to allelochemicals are often species-specific and concentration dependent, being often stimulatory at low concentrations and inhibitory at higher concentrations (7). Understanding the mechanisms underlying plant responses to allelochemicals released into the soil is vital to determining the role of allelopathy in plant communities. ...
We investigated the differential responses of two contrasting rice cultivars (susceptible BS-2000 and less susceptible BR-41) to coumarin at the cytological, biochemical and morphological levels. Both rice cultivars, showed similar trend in the relative sensitivities of specific root parameters to coumarin: total number of root hairs >total number of lateral roots > radical length. However, the light and electron microscopic observations of seedling root and leaf cells exhibited differential responses to coumarin exposure. BR-41 showed higher ribosomal density (RD), more mitochondria in root cells, larger starch granules in leaves and more vacuoles (smaller size) than BS-2000. Coumarin also induced different antioxidant responses in two cultivars. BR-41 showed 23% higher superoxide dismutase (SOD), 16% higher catalase (CAT) and 17% higher peroxide dismutase (POD) activities than BS-2000 when exposed to 400 μM coumarin. However, malondialdehyde (MDA) contents and electrolyte leakage were significantly higher in BS-2000, which exhibited 8 and 10 % higher MDA levels and 49 and 45% higher electrolyte leakage than BR-41, when exposed to 200 and 400 μM coumarin, respectively. Our results suggested that biochemical and cytological responses and root morphological characteristics jointly affect the rice resistance to coumarin stress
... Short-range chemical interactions and limited dispersion allow for coexistence of competing planktonic species that could not coexist in a well-mixed environment [104]. Among the different chemical interaction models, it is mostly those for allelopathic interactions that have been transposed from terrestrial to the planktonic component of aquatic systems [105]. Recent progress in understanding chemical interactions in the plankton has promoted the use of these models. ...
Marine chemical ecology comprises the study of the production and interaction of bioactive molecules affecting organism behavior and function. Here we focus on bioactive compounds and interactions associated with phytoplankton, particularly bloom-forming diatoms, prymnesiophytes and dinoflagellates. Planktonic bioactive metabolites are structurally and functionally diverse and some may have multiple simultaneous functions including roles in chemical defense (antipredator, allelopathic and antibacterial compounds), and/or cell-to-cell signaling (e.g., polyunsaturated aldehydes (PUAs) of diatoms). Among inducible chemical defenses in response to grazing, there is high species-specific variability in the effects on grazers, ranging from severe physical incapacitation and/or death to no apparent physiological response, depending on predator susceptibility and detoxification capability. Most bioactive compounds are present in very low concentrations, in both the producing organism and the surrounding aqueous medium. Furthermore, bioactivity may be subject to synergistic interactions with other natural and anthropogenic environmental toxicants. Most, if not all phycotoxins are classic secondary metabolites, but many other bioactive metabolites are simple molecules derived from primary metabolism (e.g., PUAs in diatoms, dimethylsulfoniopropionate (DMSP) in prymnesiophytes). Producing cells do not seem to suffer physiological impact due to their synthesis. Functional genome sequence data and gene expression analysis will provide insights into regulatory and metabolic pathways in producer organisms, as well as identification of mechanisms of action in target organisms. Understanding chemical ecological responses to environmental triggers and chemically-mediated species interactions will help define crucial chemical and molecular processes that help maintain biodiversity and ecosystem functionality.
... Short-range chemical interactions and limited dispersion allow for coexistence of competing planktonic species that could not coexist in a well-mixed environment [104]. Among the different chemical interaction models, it is mostly those for allelopathic interactions that have been transposed from terrestrial to the planktonic component of aquatic systems [105]. Recent progress in understanding chemical interactions in the plankton has promoted the use of these models. ...
Marine chemical ecology comprises the study of the production and interaction of bioactive molecules affecting organism behavior and function. Here we focus on bioactive compounds and interactions associated with phytoplankton, particularly bloom-forming diatoms, prymnesiophytes and dinoflagellates. Planktonic bioactive metabolites are structurally and functionally diverse and some may have multiple simultaneous functions including roles in chemical defense (antipredator, allelopathic and antibacterial compounds), and/or cell-to-cell signaling (e.g. polyunsaturated aldehydes [PUAs] of diatoms). Among inducible chemical defenses in response to grazing there is high species-specific variability in the effects on grazers, ranging from severe physical incapacitation and/or death to no apparent physiological response depending on predator susceptibility and detoxification capability. Most bioactive compounds are present in very low concentrations, in both the producing organism and the surrounding aqueous medium. Furthermore, bioactivity may be subject to synergistic interactions with other natural and anthropogenic environmental toxicants. Most, if not all phycotoxins are classic secondary metabolites, but many other bioactive metabolites are simple molecules derived from primary metabolism (e.g., PUAs in diatoms, DMSP in prymnesiophytes). Producing cells do not seem to suffer physiological impact due to their synthesis. Functional genome sequence data and gene expression analysis will provide insights into regulatory and metabolic pathways in producer organisms, as well as identification of mechanisms of action in target organisms. Understanding chemical ecological responses to environmental triggers and chemically-mediated species interactions will help define crucial chemical and molecular processes that help maintain biodiversity and ecosystem functionality.
... All plant structures, including roots, stems, leaves, flowers, fruits, and seeds, are capable of releasing chemicals into the environment (45). Plant responses to allelochemicals are often species-specific and concentration dependent, being often stimulatory at low concentrations and inhibitory at higher concentrations (7). Understanding the mechanisms underlying plant responses to allelochemicals released into the soil is vital to determining the role of allelopathy in plant communities. ...
The sustainable management of the environment and crop production in modern agriculture involves dealing with challenges from climate change, environmental pollution, depletion of natural resources, as well as pressure to cope with dependence on agricultural inputs. Balancing crop productivity with environmental sustainability is one of the main challenges for agriculture worldwide. The emergence of weeds resistant to synthetic herbicides generates huge economic losses, so unconventional weed control strategies, especially those based on ecological principles, are very much needed in modern agriculture. Incorporating a natural eco-friendly approach—allelopathy—as a tool in an integrated weed control plan by growing specific crops or spraying fields with extracts containing allelopathic compounds can significantly reduce the use of herbicides. Allelopathy is considered a multi-dimensional phenomenon occurring constantly in natural and anthropogenic ecosystems, by which one organism produces biochemicals that influence the growth, survival, development, and reproduction of other organisms. The objective of this systematic literature review is to present a comprehensive overview of allelopathy, define this phenomenon, and classify allelochemicals. This paper also discusses and highlights recent advances, ongoing research, and prospects on plant allelopathy management practices applied in agriculture, and the underlying allelopathic mechanisms. The review suggested the holistic view of some allelochemicals as an ecological approach to integrated weed control and is an important contribution to future research directions of multidisciplinary programs, chemoinformatic tools, and novel biotechnology methods to plant breeding.
The objective of this work was to evaluate the allelopathic potential of Poincianella pyramidalis and Mimosa tenuiflora on the physiological quality of Mimosa caesalpiniifolia seeds and seedlings. The sowing was carried out in sterilized soil and moistened with the aqueous leaf extract 0, 25, 50, 75 and 100 g L-1 and conditioned in germinator at 25 ºC and photoperiod of 12 hours. Germination, first count and germination speed, length and dry mass of shoots and roots were evaluated. When the concentration of the extracts of P. pyramidalis was increased, it was observed a negative allelopathic effect for first counting, GSI, shoot length. The germination and length of the aerial part showed reduction from 75 g L-1 extract of M. tenuiflora. The dry mass of the shoot was observed to decline as the concentrations were elevated. The extract of P. pyramidalis does not affect the germination of M. caesalpiniifolia seeds, however it exerts a negative effect on the physiological quality of the seedlings of this species. The extract of M. tenuiflora negatively affects germination and initial seedling growth of M. caesalpiniifolia from 75 g L-1.
β-Caryophyllene is an important volatile sesquiterpene of plants that may serve as allelochemical to influence the neighboring plant growth or as an indirect defence to attract natural herbivore enemies. A partial cDNA for β-caryophyllene synthase gene was isolated from the expressed sequence tag (EST) library of Mikania micrantha leaves. The full length cDNA of β-caryophyllene synthase from M. micrantha, designated as MmCS was obtained by rapid amplification of cDNA ends (RACE) methods. This MmCS cDNA is 1898 bp in full length and it encodes a putative protein of 547 amino acids. MmCS expression was significantly increased in M. micrantha leaves within 3-days after wounding during a 5-day interval following mechanical wounding. Bioassay showed that β-caryophyllene at ≥ 3 mg L-1 significantly inhibited the germination rates and seedling growth of Brassica campestris and Raphanus sativus. These results suggest that β-caryophyllene synthase and β-caryophyllene may play an important role in allelopathy for successful invasion of M. micrantha.
Caryophyllene is an important volatile sesquiterpene of plants that may serve as allelochemical to influence the neighboring plant growth or as an indirect defence to attract natural herbivore enemies. A partial cDNA for β-caryophyllene synthase gene was isolated from the expressed sequence tag (EST) library of Mikania micrantha leaves. The full length cDNA of β-caryophyllene synthase from M. micrantha, designated as MmCS was obtained by rapid amplification of cDNA ends (RACE) methods. This MmCS cDNA is 1898 bp in full length and it encodes a putative protein of 547 amino acids. MmCS expression was significantly increased in M. micrantha leaves within 3-days after wounding during a 5-day interval following mechanical wounding. Bioassay showed that β-caryophyllene at ≥ 3 mg L-1 significantly inhibited the germination rates and seedling growth of Brassica campestris and Raphanus sativus. These results suggest that β-caryophyllene synthase and β-caryophyllene may play an important role in allelopathy for successful invasion of M. micrantha.
