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• All four extracts had a negative effect on the germination of species tested. • The A. grandiflora extract inhibited the germination more effectively in all species except V. unguiculata. • A 50 % dilution of the A. grandiflora extract made it less potent. • Extracts had a stronger effect when used to irrigate the seeds rather than a pre-germination soak. Many unpopular species are useful for medicinal and food security use. However, their extracts can be used to improve seed germination and can remove unwanted vegetation by acting as herbicides. Often, such use is based on a history of traditional practices. For example, Vhavenda villages in the Limpopo province (South Africa) use Anthocleista grandiflora leaves to cover maize and millet grains during malting to stimulate germination, but few studies have tested their efficacy or even formulated extracts out of them. This study tested the allelopathic effect of aqueous leaf extracts of Aloe ferox, Aloe marlothii, Anthocleista grandiflora and shoot extracts of Pollichia campestris. The extracts were applied at a 100 or 50 % concentration through irrigating or soaking seeds of Strychnos spinosa and common vegetable seeds of Pisum sativum, Vigna unguiculata and Zea mays were used as benchmark species. The results showed that the extracts had a significant effect (P < 0.001, P < 0.002 and P < 0.010) on the germination of three species and suppressed germination instead of enhancing it. The exception was Vigna unguiculata , where extracts had a non-significant effect (P = 0.784). The highest inhibition was observed in the crude extract of Anthocleista grandiflora (100 %), which inhibited Pisum sativum germination with a percentage inhibition of 76 %. All extracts inhibited the seed germination of Zea mays and the highest germination of 52 % was achieved compared to 87 % germination in the control (no extracts applied). None of the different extract concentrations (100 or 50 %) or application methods (irrigation and soaking) improved the seed germination of species. These results suggest the tested extracts could be useful as growth suppressors (especially Anthocleista grandiflora) of Strychnos spinosa but more research is required. [ABSTRACT FROM AUTHOR]

Phosphorus (P) levels alter the allelopathic activity of rice seedlings against lettuce seeds. In this study, we investigated the effect of P deficiency on the allelopathic potential of non-pigmented and pigmented rice varieties. Rice seedlings of the white variety Khao Dawk Mali (KDML105, non-pigmented) and the black varieties Jao Hom Nin (JHN, pigmented) and Riceberry (RB, pigmented) were cultivated under high P (HP) and low P (LP) conditions. Morphological and metabolic responses to P deficiency were investigated. P deficiency inhibited shoot growth but promoted root growth of rice seedlings in all three varieties. Moreover, P deficiency led to decreased cytosolic phosphate (Pi) and total P concentrations in both shoot and root tissues. The subsequent reduction in internal P concentration enhanced the accumulation of phenolic compounds in both shoot and root tissues of the seedlings. Subsequently, allelopathy-based inter- and intra-specific interactions were assessed using water extracts from seedlings of the three varieties grown under HP and LP conditions. These extracts were tested on seeds of lettuce, the weed Dactyloctenium aegyptium , and the same rice variety. The shoot and root extracts from P-deficient seedlings reduced the germination of all recipient plants. Specifically, the shoot extract from P-deficient KDML105 seedlings reduced the germination index (GI) of lettuce seeds to 1%, while those from P-deficient RB and JHN seedlings produced GIs of 32% and 42%, respectively. However, when rice seeds were exposed to their own LP shoot and root extracts, their GIs increased up to 4-fold, compared with the HP extracts. Additionally, the shoot extracts from P-deficient plants also stimulated the germination of D. aegyptium by about 2–3-fold, whereas the root extracts did not have this effect. Therefore, P starvation led to the accumulation and exudation of phenolics in the shoots and roots of rice seedlings, altering their allelopathic activities. To adapt to P deficiency, rice seedlings potentially release signaling chemicals to suppress nearby competing species while simultaneously promoting their own germination and growth. [ABSTRACT FROM AUTHOR]

• Weeds and other pests: insects and pathogens, are responsible for huge economic losses in agriculture. • Unjudicious use of synthetic pesticides creates resistance among pests. • Allelochemicals can be used for pest management for sustainable agriculture under changing climatic conditions. • Allelochemicals with therapeutic potential can improve human health. Agricultural productivity is stricken by abiotic and biotic constraints. The global population is rising continuously, intensifying the pressure on crop productivity. An increase in pest populations, plant pathogens and invasive plants due to climate-related changes can cause significant reductions in yields on arable land. The excessive use of synthetic pesticides has triggered environmental pollution thereby, health hazards. Sustainable agriculture is now focused on ensuring global food security through a range of innovative and environmentally friendly approaches for pest control. Crop plants release allelochemicals into the environment by leaching, foliar decomposition and volatilization from different parts of the plant. These phytochemicals can inhibit the growth of weeds and can be toxic to crop pests. The present review focuses on utilizing allelochemicals as biopesticides for the control of pests, pathogens and weeds. It also sheds light on the use of allelochemicals for the production of plant-based pharmaceuticals. Furthermore, the studies on gene regulation for enhancement of allelochemicals and genetic modifications for crop improvement will pave the way for future research on the development of phytochemicals as a potential tool for sustainable agriculture in agroecosystems. [ABSTRACT FROM AUTHOR]

• Lichens produce more than one thousand of unique secondary metabolites. • These substances posse many biological and ecological roles, including allelopathy. • Lichen metabolites may act as phytotoxic substances, causing oxidative stress in photobiont cells. • Presence of evernic acid and usnic acid decrease content of ascorbic acid and glutathione. • Lichen compounds change composition of phenolic compounds in algal partner of symbiosis. In the present work, we studied the influence of lichen secondary metabolites (evernic acid, orcinol, usnic acid) on selected species of algae: Trebouxia erici , photobiont of lichen Cladonia cristatella producing typical lichen secondary metabolites, Coccomyxa solorinae-saccatae , photobiont of lichen Solorina saccata which does not produce typical secondary metabolites of lichens, and free-living alga Scenedesmus quadricauda. For the determination of the cytotoxic effects of these compounds, algae were cultivated on the surface of disks composed of glass microfibers, in quantities of 0.1 mg/disk for each metabolite. After 14-day s prolonged cultivation, we analysed selected physiological parameters: growth of algae, chlorophyll a fluorescence, the content of ascorbic acid, content of reduced and oxidized glutathione and contents of selected organic acids. The presence of secondary compounds typically inhibited the growth of tested algae and chlorophyll a fluorescence. In the presence of evernic acid and usnic acid, we observed a decrease of ascorbic acid, glutathione, and significant changes in the composition of organic acids. Lichen metabolites, except for their other biological and ecological roles, may act as phytotoxic substances, causing oxidative stress in photobiont cells. These metabolites may play an important role in the "controlled parasitism" of fungal partner on algal/cyanobacterial partner of symbiosis. Differences in the sensitivity of algal cells from different habitats to lichen compounds are, however, not understood sufficiently. [ABSTRACT FROM AUTHOR]

Invasive alien plants (IAPs) are recognized as major threats to the environmental and ecological systems with great potential to disrupt global biodiversity, forestry, livelihood, and human health. Nevertheless, ecological and socio-economic investigations of IAPs to facilitate restoration strategies are insufficient in many species. The potential risks posed by Tithonia diversifolia (Hemsl.) A. Gray, an emerging Asteraceae IAP has scantily been addressed in terms of its nature and/or impacts (e.g., phytochemistry, allelo/aroma-chemicals, chemical ecology, livelihood, and human well-being). This review aims to provide a first-hand assessment on potential threats and benefits of T. diversifolia and other Asteraceae IAPs in a multifaceted 'environment-agriculture-energy-health nexus' or 'biorefinery' prospects. Standard methods were used to quest the multifaceted implications of T. diversifolia invasion, mainly in the time frame of 2011 to 2023. Research platforms such as Scopus, Sciencedirect, and Google Scholar facilitated the literature collection. Adequate operation of filters was performed in selecting articles (n = 255) to deliver the state of the art knowledge in South Africa and globally. Applications of T. diversifolia are also discussed to cover diverse fields (e.g., agriculture, food industry, pharmaceuticals, bio/ethnomedicine, environmental remediation, bioenergy, biochar production, and phytosynthesis of engineered nanoparticles). An explicit assessment of IAPs can enable a judicial cost-benefit analysis to help determine its ecological economics while pursuing the targets of the United Nations Sustainable Development Goals and Decade on Ecosystem Restoration. [Display omitted] • Invasive alien plants (IAPs) in Asteraceae can exert detrimental impacts on the biodiversity, environment, agriculture, and livelihood. • Reproductive attributes and allelochemic metabolites of T. diversifolia can facilitate their landscape spread. • Biomedical and biorefinery prospects of IAP are explored using T. diversifolia. • T. diversifolia can contribute to agriculture, environmental remediation, and human health facilitating sustainable management [ABSTRACT FROM AUTHOR]

• Medicinal plants can show allelopathic potential. • Plant extracts rich in phenols, flavonoids and tannins showed high allelopathic activities. • Annona dioica (Annonaceae), Stryphnodendron adstringens (Fabaceae) and Palicourea crocea (Rubiaceae) decelerated U. decumbens seed germination. • Alternative methods for controlling U. decumbens in areas of ecological restoration. Invasive grasses, those of the genus Urochloa act aggressively, thereby inhibiting the germination and growth of native species. We investigated the allelopathic potential and constituent content of different plant species to determine their effect on the germination of Urochloa decumbens (Stapf) R.D. Webster. Eighteen (18) species from the families Anacardiaceae (1), Annonaceae (6), Euphorbiaceae (1), Fabaceae (2), Myrtaceae (1), Rubiaceae (4), Sapindaceae (2), and Tropaeolaceae (1) were selected to obtain methanolic extracts at 1% (m/v). The total phenols, flavonoids, condensed tannins, flavonols, and saponins were evaluated by colorimetric methods. To evaluate the allelopathic effect of methanolic extracts 25 seeds from U. decumbens were distributed in Petri dishes containing two sheets of germitest paper and 2 mL of extract, and they were maintained at 25 °C under white light. All methanolic extracts showed total phenols, flavonoids, flavonols, and condensed tannins; however, saponin was identified in A. coriacea, A. crassiflora, A. sylvatica, Psychotria carthagenensis, P. leiocarpa, and Tropaeolum majus. Annona dioica (Annonaceae), Stryphnodendron adstringens (Fabaceae), and Palicourea crocea (Rubiaceae) have allelopathic potential and showed decelerated U. decumbens seed germination and inhibited hypocotyl and radicle growth. These findings provide insights into alternative methods for controlling U. decumbens in areas of ecological restoration. [ABSTRACT FROM AUTHOR]

• A.brevifolia samples were collected from four locations between the altitude range 2800–4500 masl. • The content of total phenol and flavonoid decreases with increasing altitude. • The radical scavenging potential and phytotoxic effect of extracts decreases with an increase in altitude. • This decrease in phenolic content, antioxidant and allelopathic effect might be due to a declining number of competitive plants and available resources with increasing altitude. The climatic conditions change particularly in the high-altitude mountain ranges of the Himalayas. Artemisia brevifolia Wall. ex Dc., a pale green colored medicinal and aromatic plant, dominates different altitudinal locations in the Western Himalayan region of Ladakh. Metabolome analysis with antioxidative and allelopathic potential of the plant extracts from different altitudes was evaluated, with an aim to understand the interaction of the plant with its surroundings. The results showed decreasing concentration of total phenol and flavonoids with the increase in altitude. Metabolome analysis using FTIR points toward the presence of aromatic compounds, phenolic compounds and sesquiterpene lactones in all the samples with highest peak intensity in samples from Drass region of Ladakh. Overall, the metabolome analysis showed decreasing concentration of bioactive phenolics with the increase in altitude. The antioxidant activity of the sample extracts from low-altitude sites showed a higher inhibition percentage compared to high-altitude sites. Overall, the leaf extracts and powdered samples from different altitudes inhibited the germination and growth parameters of both dicotyledon (Medicago sativa L.) and monocotyledon (Triticum aestivum L.) in a concentration-dependent manner, under both in vitro and in vivo experimental conditions. Compared to germination rate and shoot length, the root length of both seedlings was strongly inhibited. The allelopathic potential of the extract and powdered samples also decreases with an increase in the altitude of the sampling site. These results indicate that the overall content of phenolics, radical scavenging potential and allelopathic potential decrease with an increase in altitude, which might be an adaptive strategy of A. brevifolia to conserve limited available resources at high altitudes. [ABSTRACT FROM AUTHOR]

• The two Asteraceae invasive plants triggered notable allelopathy on L. sativa. • The allelopathy of S. canadensis was greater than that of C. canadensis. • Salt stress strengthened the allelopathy of the two Asteraceae invasive plants. • Light salt stress created a stronger impact on the allelopathy of S. canadensis. The allelopathy of invasive plants is crucial to their successful invasion. The co-invasion of two invasive plants is common. Salt stress may affect the allelopathy of invasive plants, particularly the co-allelopathy of two invasive plants. This study aimed to analyze the independent allelopathy and the co-allelopathy of two Asteraceae invasive plants, Solidago canadensis L. and Conyza canadensis (L.) Cronq., on seed germination and seedling growth of the horticultural Asteraceae species Lactuca sativa L. under a gradient of salt stress. The germination bioassay of L. sativa was conducted via the incubation in Petri dishes (diameter: 9 cm). The two Asteraceae invasive plants caused significant allelopathy on L. sativa. The independent allelopathy of S. canadensis was greater than that of C. canadensis and the co-allelopathy of the two Asteraceae invasive plants. Salt stress regardless of the concentration strengthened the independent allelopathy and the co-allelopathy of the two Asteraceae invasive plants. Heavy salt stress triggered a stronger impact on the independent allelopathy and the co-allelopathy of the two Asteraceae invasive plants than light salt stress. The degree of enhancement for the independent allelopathy of S. canadensis on L. sativa was clearly greater than that of C. canadensis and the co-allelopathy of the two Asteraceae invasive plants under light salt stress, but it was similar in the degree of enhancement for the independent allelopathy and the co-allelopathy of the two Asteraceae invasive plants under heavy salt stress. [ABSTRACT FROM AUTHOR]

The issue of eutrophication of water bodies has attracted worldwide attention. Ecological restoration is a promising method to prevent and control eutrophic water bodies. Submerged macrophytes are widely used in the restoration processes. It can not only provide abundant food and habitat for zooplankton, but also inhibit the growth of algae through allelopathy or nutrient competition. This article provides a comprehensive review on research status on the remediation of eutrophic water by submerged macrophytes, with emphasis on the main affecting factors for their growth, including nutrients, light, water depth, sediment, temperature, biochar, transparency, and water flow. The optimum growth conditions of submerged macrophytes are further analyzed to provide guide for further studies and rear applications on the remediation of eutrophic water by submerged macrophytes. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of a competition model of plankton allelopathy imposed in time-space periodic environment. We prove that the system admits positive periodic solutions under certain conditions. We further obtain some sufficient conditions for the uniqueness and global stability of the positive periodic solution, which shows that the model is persistent. The main tools for our arguments are comparison theorems based on the maximum principle, sub- and supersolutions method, and an iteration method, which also permit the treatment of some more general reaction–diffusion models in periodic environment. [ABSTRACT FROM AUTHOR]

The dinoflagellate Amphidinium carterae is a promising source of unique bioactive compounds with potential applications in diverse industries. Abiotic strategies for increasing bioactive cell quota have been preferred for cost-effectiveness, controllability, and existing knowledge. The supernatants of Heterosigma akashiwo and Pavlova sp. enhanced haemolytic activity of A. carterae by 2.3 times and improved its final biomass by 10 % when added to the growth medium. Prymnesium parvum supernatant increased the total lipid content of A. carterae by 50 %, while Pleurochrysis roscoffensis supernatant boosted its total carotenoid content by 40 %. This study demonstrated a rapid screening strategy for evaluating growth responses and highlights the potential of using allelopathic strategies to enhance bioactive metabolite production. Utilizing supernatants for the formulation of growth media fosters a circular economy by repurposing resources, minimizing waste, and promoting sustainability in the microalgal biotechnological industry. [Display omitted] • 38 microalgal supernatants were evaluated for stimulating A. carterae. • Quorum sensing allowed increasing total lipid and carotenoid content. • Evidence of amphidinols overproduction was found for many species. • Repurposing supernatants as a biostimulant enhances circularity. [ABSTRACT FROM AUTHOR]

This study examined effects of mangrove plants Kandelia obovata and Aegiceras corniculatum on harmful algal species. While A. corniculatum leaf extract had no inhibitory effect, K. obovata leaf extract significantly inhibited the growth of two harmful algal species Alexandrium tamarense and Karenia mikimotoi. The inhibitory effect was concentration-dependent, with over 90 % inhibition at the highest concentration. Morphological changes and cell size reduction were observed in both microalgae. Excessive production of reactive oxygen species and damage to algal photosynthetic system were found. The allelopathic effect of K. obovata on K. mikimotoi with low-concentration repeated exposure was more effective than high-concentration single exposure. The EC 50 of K. obovata (0.33 g L−1) was lower than reported values on other coastal plants. Higher inhibitory effects of K. obovata were found on naked algal species than the armoured ones. These findings suggest potential applications of K. obovata leaf extract in controlling harmful algal blooms. • Allelopathy: algal species-specific and mangrove leaf concentration-dependent • K. obovata leaf extract significantly inhibited growth of harmful algal species • K. obovata caused algal ROS production, morphological changes, photosystem damage • Low-concentration repeated exposure better than high-concentration single exposure [ABSTRACT FROM AUTHOR]

Contributing to the assessment of potential physiological changes in microalgae subjected to different concentrations and types of cyanotoxins, this study investigated the inhibitory effects of cyanotoxins on the growth, density, biomass, and ecotoxicity of Chlorella vulgaris. Chlorella vulgaris was exposed to crude extracts of cyanobacteria producing microcystin-LR (MC-LR), saxitoxin (SXT), anatoxin-a (ATX-A), and cylindrospermopsin (CYN) with initial concentrations of 5.0, 2.05, 0.61, and 1.42 μg.L−1, respectively. The experiments were conducted under controlled conditions, and monitoring of growth and cell inhibition occurred at 24h, 48h, 72h, and 96h. Chlorophyll-a content and ecotoxicity assessment were conducted with samples collected after 96h of exposure to cyanotoxins. The growth assays of Chlorella vulgaris , with results expressed in terms of average growth rates (doublings/day), indicated the following order for cyanotoxins: SXT (2.03) > CYN (1.66) > MC-LR (1.56) > ATX-A (0.18). This assay revealed the prominent inhibitory potential of ATX-A on Chlorella vulgaris growth compared to the other toxins evaluated. Regarding the inhibition of the photosynthetic process, expressed in terms of the percentage inhibition of Chlorophyll-a, the following order for cyanotoxins was obtained: ATX-A (82%) > MC-LR (76%) > STX (46%) > CYN (16%). These results also indicated that among the cyanotoxins, ATX-A was the most detrimental to the photosynthetic process. However, contrary to the observations in the growth study, SXT proved to be more harmful than CYN in terms of Chlorophyll-a inhibition. Finally, the results of the toxicity assay revealed that only ATX-A and MC-LR exerted a chronic influence on Chlorella vulgaris under the investigated conditions. [Display omitted] • Phytotoxicity of cyanotoxins induces different physiological responses to Chlorella vulgaris. • MC-LR and ATX-A promote greater inhibitory effects on the growth, density, biomass and ecotoxicity of Chlorella vulgaris. • The lowest inhibitions of algal growth among the cyanotoxins were for SXT and CYN. • The percentage inhibition of Chlorophyll –a was: ATX-A (82%) > MC-LR (76%) > SAX (46%) > CYN (16%). [ABSTRACT FROM AUTHOR]

• A microdialysis-HPLC was applied in detecting allelochemicals for the first time. • An in-situ detected method without damaging rhizosphere structure was established. • Detection limits were 1.23 µg/g for five phenolic acids. Microdialysis is an important technology in the field of medicine, and with the popularization and development of microdialysis technology, it has been gradually applied to the field of ecology. In this study, microdialysis-HPLC as a new and environmentally friendly in situ technique was developed and applied for the first time to detect phenolic acid allelochemicals in Rehmannia glutinosa rhizosphere. A response surface analysis (RSM) was used to optimize the microdialysis in situ based on the Box–Behnken design (BBD) experiment. The optimum dialysis conditions were obtained as follows: the perfusion solution was a NaCl solution of 200 mmol/L with pH 4, and the dialysis temperature was 37 °C. Under these conditions, the content of phenolic acids in the rhizosphere 10, 20 and 30 cm away from the root was analyzed using high-performance liquid chromatography (HPLC) detection combined with the standard curve of phenolic acid addition. Compared to traditional methods, microdialysis-HPLC is a simple and environmentally friendly method for the in situ detection of phenolic acids in rhizosphere. [ABSTRACT FROM AUTHOR]

The effects of culture filtrate of Alexandrium tamarense on Prorocentrum donghaiense and Heterosigma akashiwo were investigated, including determination of algal density, photosynthesis, intracellular enzyme content and activity. The filtrate of A. tamarense had a stronger inhibitory effect on P. donghaiense than H. akashiwo , and the inhibitory effect decreased with higher temperature treatment of the filtrate. Instantaneous fluorescence (Ft) and maximum quantum yield of photosystem II (Fv/Fm) values of both kinds of target algae were reduced as exposed to the filtrate of A. tamarense , which proved that allelopathy could inhibit the normal operation of photosynthetic system. The increase of Malondialdehyde (MDA) content of the two kinds of target algae indicated that the cell membrane was seriously damaged by allelochemicals released by A. tamarense. The different responses of Superoxide Dismutase (SOD) and Catalase (CAT) activity in two kinds of target algae demonstrated the complexity and diversity of allelopathic mechanism. The filtrate of A. tamarense also influenced the metabolic function (ATPases) of P. donghaiense and H. akashiwo, and the influence on P. donghaiense was greater. Liquid-liquid extraction was used to extract and isolate allelochemicals from the filtrate of A. tamarense. It was found that only component I with molecular weight of 424.2573 and 434.2857 could inhibit the growth of P. donghaiense by HPLC-MS. [Display omitted] • The filtrate of Alexandrium tamarense inhibited the growth of Prorocentrum donghaiense and Heterosigma akashiwo. • The inhibitory effect on P. donghaiense was stronger than that of H. akashiwo , and decreased after higher temperature treatment of the filtrate. • The filtrate of A. tamarense reduced the photosynthetic efficiency (Ft and Fv/Fm values) of both kinds of target algae. • The filtrate of A. tamarense influenced the oxidative stress (SOD, MDA and CAT) and metabolic function (ATPases) of both kinds of target algae. • Two unkown compounds with a molecular weight of 424.2573 and 434.2857 were suggested to be the alleochemicals released by A. tamarense. [ABSTRACT FROM AUTHOR]

Crop infestation species have acquired resistance to herbicides, stimulating the search for new control methods. Plants secondary metabolites can hold more sustainable alternatives, as they can be used for development of natural herbicides. This study evaluated phytotoxic effects of aqueous extracts of Ilex paraguariensis leaves on Conyza bonariensis , an infesting species of Brazilian crops. Different concentrations of decoction and infusion extracts were tested in germination and growth bioassays. Adult plants were evaluated for leaf anatomy effects caused by the yerba mate extract. HPLC analysis was used to quantify the three major chemical constituents. The most effective aqueous extract (decoction 1.0%) decreased the percentage of seed germination, germination speed index, and percentage of germination-derived seedling formation, and increased the time for seedling formation. Shoot and root growth were not affected by this extract. In adult plants, the same extract damaged epidermis and palisade/lacunous parenchyma six hours after exposure. Caffeine was found as the major compound of this extract, followed by rutin and quercetin. Therefore, aqueous extract by decoction 1.0 % of I. paraguariensis leaves showed potential for control of C. bonariensis infestation and rather promising for the development of a natural herbicide. [ABSTRACT FROM AUTHOR]

• Cucurbit crops synthesize cucurbitacins. • Biochemical analysis of cucurbitacins can enhance their use. • Molecular markers and quantitative trait loci associated with cucurbitacins can facilitate their genetic improvement. The cucurbitaceae family comprises of economically important vegetable crops grown for food and medicine. Most cucurbit crops produce cucurbitacins in leaves, flowers, fruit, seed and roots which possess various pharmacological and pharmaceutical values. Cucurbitacins are toxic to pests and diseases, and allelopathic to noxious weeds thus providing opportunities for improving tolerance to biotic stresses. Further, cucurbitacins are responsive to environmental stimuli and can therefore enhance tolerance to abiotic stress. The objective of this review was to highlight the breeding value of cucurbitacins to develop cucurbitacins-enriched genotypes for food and medicine, and for management of biotic and abiotic stresses. The following themes were discussed: a comparative analysis of cucurbitacin concentrations in edible and non-edible plant parts; genetic control and associated quantitative trait loci and molecular markers associated with cucurbitacins; pharmacological and pharmaceutical values of cucurbitacins, and potential applications for management of biotic and abiotic stresses. Results of the present study will guide genetic improvement of cucurbitacins for use as food and medicine, and in the development of genotypes tolerant to biotic and abiotic stresses. [ABSTRACT FROM AUTHOR]

• A. indica has an allelopathic effect on the germination of M. urundeuva seeds. • A. indica is capable of reducing photosynthetic pigments. • A. indica released margocinolid, epoxyazadiradione, margosinona, iso-azadirolida. Azadirachta indica have allelopathic potential, attributed to the presence of allelochemicals capable of altering plant diversity in surrounding areas. This work aimed to evaluate if the decomposed leaves of A. indica can affect the germination and growth of Myracrodruon urundeuva. A. indica leaves were collected at the end of senescence and mixed with soil in different concentrations and decomposed for 90 and 180 days. Through phytochemical analysis, it was found the presence of diterpenes and triterpenes, such as margocinolide, epoxyazadiradione and salimuzzalin. Leaf decomposition negatively affected germinability, emergence speed and the germination synchrony index of M. urundeuva , especially during the first decomposition period. The residues of the leaves of A. indica also negatively affected the length of the young plants of M. urundeuva , since the lengths of the stem and root were reduced, and the treatment of lower concentration a reduction in root length was observed only in the first decomposition period (T1). Leaf residues in the first decomposition time also negatively influenced the total biomass of M. urundeuva , in all treatments evaluated. The decomposition were also able to change the amount of photosynthetic pigments in the first decomposition period, since the total chlorophyll content had a reduction from the average value of 3.23 to 2.40 g/kg, corresponding to a 25.71 inhibition. The observed results suggest that the compounds present in the litter of A. indica have an allelopathic action, being necessary to limit the use of the former in areas that need ecological restoration and in preserved natural environments. [ABSTRACT FROM AUTHOR]

Vegetation patterning in water-limited and other resource-limited ecosystems highlights spatial self-organization processes as potentially key drivers of community assembly. These processes provide insight into predictable landscape-level relationships between organisms and their abiotic environment in the form of regular and irregular patterns of biota and resources. However, two aspects have largely been overlooked; the roles played by plant – soil-biota feedbacks and allelopathy in spatial self-organization, and their potential contribution, along with plant-resource feedbacks, to community assembly through spatial self-organization. Here, we expand the drivers of spatial self-organization from a focus on plant-resource feedbacks to include plant – soil-biota feedbacks and allelopathy, and integrate concepts of nonlinear physics and community ecology to generate a new hypothesis. According to this hypothesis, below-ground processes can affect community assemblages through two types of spatial self-organization, global and local. The former occurs simultaneously across whole ecosystems, leading to self-organized patterns of biota, allelochemicals and resources, and niche partitioning. The latter occurs locally in ecotones, and determines ecotone structure and motion, invasion dynamics, and species coexistence. Studies of the two forms of spatial self-organization are important for understanding the organization of plant communities in drier climates which are likely to involve spatial patterning or re-patterning. Such studies are also important for developing new practices of ecosystem management, based on local manipulations at ecotones, to slow invasion dynamics or induce transitions from transitive to intransitive networks of interspecific interactions which increase species diversity. • Spatial self-organization (SSO) drives community assembly in infertile ecosystems. • Soil biota and allelopathy provide new mechanisms for SSO. • Spatial self-organization emerging from these mechanisms can be global or local. • Novel belowground mechanisms expand insight from SSO to exotic invasions. [ABSTRACT FROM AUTHOR]

• Since the first description of the fairy circles 50 years ago, the cause is still hotly debated. • The first review paper in nearly 20 years on the fairy circles of the Namib Desert. • The contrasting main theories on the formation and maintenance of fairy circles are discussed. • The physical characteristics of fairy circles are described and critically reviewed. Since they were described for the first time 50 years ago, more than 30 peer-reviewed papers have been published on a number of extremely diverse theories as the cause of the formation of hundreds of thousands of nearly circular barren patches (fairy circles) found in southwestern Angola, Namibia and northwestern South Africa. However, scientists interested in finding an explanation for the cause and maintenance of these fairy circles in the driest parts of the world are still without agreement on the true reason(s) behind this intriguing phenomenon. In this review we firstly present the four main theories and explain their hypotheses on the formation and/or maintenance of fairy circles. Secondly, we summarise the previously described physical characteristics of the fairy circles, e.g. soil substrate, moisture content, shape, size, lifespan, dynamics and spatial patterning, and then present the supporting evidence as published by the proponents of the theories on vegetation self-arrangement, insects/ants, gas and Euphorbia allelopathy, as the causative drivers of this natural phenomenon. We also present the critical views of scientists on the theories they are not supporting. [ABSTRACT FROM AUTHOR]

• Ethanolic extracts of mushrooms were able to inhibit Pseudomonas aeruginosa growth. • Additive antibacterial is observed by the combination of the ethanolic extracts. • Cytotoxicity for 2.5 mg/mL of the R. xerampelina extract was observed on Vero cells. • Non-significant decreases in lettuce and tomato seeds germination were observed. • Allelopathic positive index of lettuce and tomato seeds exposed to extracts. New products, including natural extracts, have been evaluated for the control of phytopathogens. This study aimed to evaluate the antibacterial potential of ethanolic extracts from mushrooms, followed by an evaluation of allelopathic effects. Characterization of phenolic acids in Russula xerampelina (Schaeff.) Fr., Crab Brittlegill. and Suillus granulatus (L.) Roussel, Weeping Bolete extracts were evaluated by high-performance liquid chromatography, followed by assessment of their antibacterial potential, alone and combined, against Pseudomonas aeruginosa. The allelopathic effects of Lactuca sativa (lettuce) and Solanum lycopersicum (tomato) were measured in terms of germination and length parameters. The results demonstrated an additive profile of the combined extracts against P. aeruginosa. Both extracts caused a decrease in the percent germination of L. sativa and S. lycopersicum seeds at higher concentrations. Seeds were positively influenced when analyzing the allelopathic index. These results indicate the potential of these extracts for control of genus Pseudomonas phytopathogens, mainly because they do not cause phytotoxicity in terms of the evaluated parameters. [ABSTRACT FROM AUTHOR]

Allelopathy is considered as a physiological phenomenon with ecological implications that have stimulatory or inhibitory effects on organisms. The aim of the present study was focused on the effect of Ulva lactuca aqueous extract on growth and some physiological and metabolic aspects as well as gene expression of both Dunaliella salina and Chlorella salina. Linoleic acid ethyl ester; Propanoic acid, 3-(methylthio); Ethanol, 2-(9-octadecenyloxy)-, (Z); Oleic Acid; and 9-Octadecynoic acid, methyl ester were active phytochemical compounds detected from the gas chromatography-mass spectrometry (GC–MS) analysis for the donor species aqueous extract. Data revealed that U. lactuca contains appreciable amounts of Mg, K, Ca, Na and Fe. Results showed a dramatic effect of U. lactuca extracts on growth of both D. salina and C. salina , which significantly increased at low extract concentrations and vice versa. The activity of total antioxidants achieved a gradual increase by increasing the extract concentration. Furthermore, the two recipient algae attained the highest value of protein polymorphism under 10% extract concentration. Sequences of soluble inorganic pyrophosphatases (sPPases) gene showed that, allelochemicals of U. lactuca extract reflected the highest genetic variation in C. salina and D. salina while causing a significant variation in different biochemical parameters. [ABSTRACT FROM AUTHOR]

The genus Vincetoxicum includes a couple of highly invasive vines in North America that threaten biodiversity and challenge land management strategies. Vincetoxicum species are known to produce bioactive phenanthroindolizidine alkaloids that might play a role in the invasiveness of these plants via chemical interactions with other organisms. Untargeted, high-resolution mass spectrometry-based metabolomics approaches were used to explore specialized metabolism in Vincetoxicum plants collected from invaded sites in Ontario, Canada. All metabolites corresponding to alkaloids in lab and field samples of V. rossicum and V. nigrum were identified, which collectively contained 25 different alkaloidal features. The biosynthesis of these alkaloids was investigated by the incorporation of the stable isotope-labelled phenylalanine precursor providing a basis for an updated biosynthetic pathway accounting for the rapid generation of chemical diversity in invasive Vincetoxicum. Aqueous extracts of aerial Vincetoxicum rossicum foliage had phytotoxic activity against seedlings of several species, resulting in identification of tylophorine as a phytotoxin; tylophorine and 14 other alkaloids from Vincetoxicum accumulated in soils associated with full-sun and a high-density of V. rossicum. Using desorption-electrospray ionization mass spectrometry, 15 alkaloids were found to accumulate at wounded sites of V. rossicum leaves, a chemical cocktail that would be encountered by feeding herbivores. Understanding the specialized metabolism of V. rossicum provides insight into the roles and influences of phenanthroindolizidine alkaloids in ecological systems and enables potential, natural product-based approaches for the control of invasive Vincetoxicum and other weedy species. [Display omitted] • Vincetoxicum vines are highly invasive in North America that threaten biodiversity. • 25 phenylalanine-derived alkaloids were identified by metabolomics. • Isotope-labelling via phenylalanine incorporation informed an updated biosynthetic pathway. • Tylophorine has phytotoxic activity and is present in soil at invaded sites. • Mass spectrometry imaging detected 15 alkaloids at wounded sites of V. rossicum leaves. [ABSTRACT FROM AUTHOR]

• We present novel findings of the angatonistic effects of Alexandrium catenella on phytoplankton under warming and acidification. • Experiments targeted three species and tested for density-dependent effects. • Growth inhibition increased under warming and acidification on Rhodomonas salina and Tetraselmis. • There was no antagonistic effect on the target diatom (Thalassiosira weissflogii) under ambient or OWA conditions. • Growth inhibition under OWA conditions may alter phytoplankton community composition by affecting some groups but not others. There is a concern that harmful algal bloom (HAB) species may increase under climate change. Yet, we lack understanding of how ecological interactions will be affected under ocean warming and acidification (OWA) conditions. We tested the antagonistic effects of three strains of the dinoflagellate HAB species Alexandrium catenella on three target species (the chlorophyte Tetraselmis sp., the cryptomonad Rhodomonas salina , and the diatom Thalassiosira weissflogii) at various biomass ratios between species, at ambient (16 °C and 400 µatm CO 2) and OWA (20 °C and 2000 µatm CO 2) conditions. In these experiments the Alexandrium strains had been raised under OWA conditions for ∼100 generations. All three non-HAB species increased their growth rate under OWA relative to ambient conditions. Growth rate inhibition was evident for R. salina and Tetraselmis sp. under OWA conditions, but not under ambient conditions. These negative effects were exacerbated at higher concentrations of Alexandrium relative to non-HAB species. By contrast, T. weissflogii showed positive growth in the presence of two strains of Alexandrium under ambient conditions, whereas growth was unaffected under OWA. Contrary to our expectations, A. catenella had a slight negative response in the presence of the diatom. These results demonstrate that Alexandrium exerts higher antagonistic effects under OWA compared to ambient conditions, and these effects are species-specific and density dependent. These negative effects may shift phytoplankton community composition under OWA conditions. [ABSTRACT FROM AUTHOR]

The use of synthetic fungicides to control Fusarium wilt disease in chili (Capsicum annuum L.) caused by Fusarium oxysporum f. sp. capsici (Foc) has detrimental effects, indicating the need for nature friendly alternatives. So, in the present study, antifungal activity of Chenopodium album L. was investigated against the Fusarium wilt of chilies under pot conditions, employing 2 concentrations of C. album and Foc. The treatments were also included to investigate the individual effects of dead Foc (DFoc) as well as C. album to evaluate their effects on the morphological, biochemical and physiological attributes of chili plants. One percent of C. album concentration exhibited positive allelopathy, thereby significantly controlled the wilt disease in chili plants, leading to increases in plant height, dry biomass, chlorophyll a (Chl a), chlorophyll b (Chl b), and carotenoid content by 20, 13, 43, 35, and 8%, respectively, as compared to Foc1. Additionally, the C. album amendment spiked the activities of antioxidants, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), by 13, 20, and 26%, respectively, and significantly enhanced the photosynthetic rate (P n), transpiration rate (E), stomatal conductance (g s), and intercellular CO 2 (C i) by 20, 29, 20, and 4%, respectively, in comparison to chili plants inoculated with Foc1. • Disease suppressing ability of Chenopodium album was investigated against Fusarium wilt in chili plants. • Soil amendment with C. album increased defence related enzyme activities viz., superoxide dismutase, peroxidase, and catalase in chili plants. • Increase in antioxidants led to decreased disease incidence and severity, thereby increasing tomato plant growth. • Treatments of C. album as well as dead Fusarium inoculum depicted significant effects on chili plants depicted significant effects that implies to include these treatments in future studies. [ABSTRACT FROM AUTHOR]

• Datura metel and Inula viscosa had contrasting effects on coexisting pepper and weed. • I. viscosa treatment was the most harmful on Solanum elaeagnifolium growth. • D. metel and I. viscosa aerial parts combination affected Capsicum annuum L. growth. • Treatments were effective in pot experiments and field trials. • Respiration decrease and membrane integrity disruption could explain weed inhibition. Invasive alien plant species like Solanum elaeagnifolium Cav. decrease crop yields, demanding effective control methods. This study evaluated the phytotoxicity of Datura metel L. and Inula viscosa L. powdered aerial parts (sole or in combination) on coexisting plants, S. elaeagnifolium and Capsicum annuum L. In pot experiments, varying doses (2, 6, and 10 g Kg−1 potting soil) of D. metel and I. viscosa were spread on soil surfaces. The combination of D. metel and I. viscosa exerted pronounced phytotoxicity on C. annuum , leading to seedlings mortality at the highest dose. However, weed growth was stimulated at all doses. Sole application of D. metel and I. viscosa stimulated C. annuum shoot and root length and fresh weight. Best stimulations were respectively 88.87 %, 98.85 %, and 82.78 %, by I. viscosa at 10 g Kg−1. At this same dose, S. elaeagnifolium growth was inhibited. Therefore, surface treatments with I. viscosa on soil were evaluated in field trial. At 3.18 t ha−1, shoot and root lengths and the weight of S. elaeagnifolium were reduced (62.66 %, 72.53 % and 80.37 % respectively), while those of C. annuum were stimulated (22.36 %, 63.93 % and 40.98 %). These effects on S. elaeagnifolium were attributed to respiration decrease and an increase in malondialdehyde content and electrolyte leakage, while those on C. annuum to an increase in proline content and respiration, and the maintain of the membrane integrity. It could be concluded that soil incorporation of I. viscosa powdered aerial parts could provide effectiveness for weed control and crop yield improvement to exploit its valuable allelochemicals either to control S. elaeagnifolium or to improve C. annuum production, providing insights into the applicability of I. viscosa as potential bioherbicide and biofertilizer for sustainable weed management in horticulture crops. [ABSTRACT FROM AUTHOR]

• Exudates of Z. marina negatively affect A. minutum growth rate. • Z. marina exudates stimulate bacterial growth in A. minutum cultures. • The inhibitory effect is likely associated with substances released by Z. marina. Biotic interactions are a key factor in the development of harmful algal blooms. Recently, a lower abundance of planktonic dinoflagellates has been reported in areas dominated by seagrass beds, suggesting a negative interaction between both groups of organisms. The interaction between planktonic dinoflagellates and marine phanerogams, as well as the way in which bacteria can affect this interaction, was studied in two experiments using a non-axenic culture of the toxic dinoflagellate Alexandrium minutum exposed to increasing additions of eelgrass (Zostera marina) exudates from old and young leaves and to the presence or absence of antibiotics. In these experiments, A. minutum abundance, growth rate and photosynthetic efficiency (Fv/Fm), as well as bacterial abundance, were measured every 48 h. Toxin concentration per cell was determined at the end of both experiments. Our results demonstrated that Z. marina exudates reduced A. minutum growth rate and, in one of the experiments, also the photosynthetic efficiency. These results are not an indirect effect mediated by the bacteria in the culture, although their growth modify the magnitude of the negative impact on the dinoflagellate growth rate. No clear pattern was observed in the variation of toxin production with the treatments. [ABSTRACT FROM AUTHOR]

Climate change, environmental pollution and depletion of natural resources are among the prominent potential challenges for sustainable crop production and environment management in modern agriculture. Rice production systems have threatened with insect pests and weeds that significantly contribute to yield losses. Although control of insects, pests and weeds has remained the major effective plant protection tool, yet hazards to environmental safety urge the scientific community to propose alternative pest management strategies. Apprehensions about conventional agriculture sustainability have impelled the extensive introduction of integrated pest management (IPM). Bio-based IPM is one of the important component for controlling insect-pests, and weeds in rice, as it is environmentally benign, effective, and economically viable. In the present article, we analysed several studies to highlight the: (1) description of practices related to IPM in rice, (2) progress regarding the bio-based integrated insect pests and weed management with possible implications and scope, (3) allelopathy effectiveness for weed management in rice, and (4) present dilemmas and proposed future research directions. Briefly, this article explores the opportunities for the scientists and rice farmers to maximize the utilization of diverse natural control agents as a partial or total substitute for synthetic pesticides. [ABSTRACT FROM AUTHOR]

Decomposing litter is regarded as the most important source of allelochemicals released into soil. In this study, a greenhouse experiment was designed to assess the net effect of differently aged leaf litter from exotic (Ailanthus altissima, Robinia pseudoacacia and Ulmus pumila) and native riverine trees (Populus alba, Populus nigra and Ulmus minor) on the germination and growth of three herb species (Trifolium repens, Dactylis glomerata and Chenopodium album). We also characterized the chemical composition of litter samples at different litter ages (0, 1, 2 and 3 months) based on phenolic compounds, fibers and ergosterol (as a measure of fungal biomass) contents. Overall, litter from both native and exotic species had a negative effect on shoot and root growth of target species, indicating that phytotoxic effects of litter predominate over positive effects. The inhibition effect of the exotic species was similar or even lower than that of the natives, which does not support the Novel Weapons Hypothesis. Among exotic trees, U. pumila showed the highest inhibition effect on the growth of the target species. T. repens was the most sensitive target species. The importance of litter age varied with both target and donor species. In general, D. glomerata was more inhibited by fresh litter, C. album by half-decomposed litter of U. pumila and R. pseudoacacia and by fresh litter of A. altissima and T. repens was more inhibited by fresh litter of A. altissima and P. alba and by highly decomposed litter of U. minor. The concentration of total phenolics and flavonoids decreased while acid detergent fiber, lignin and ergosterol increased with increasing litter age. Hydroxybenzoic and protocatechuic acids and the flavonoid quercetin were detected in all litter species and at most of the litter ages, while gallic, chlorogenic, vanillic, coumaric and rosmarinic acids were species-specific and they were only detected in fresh litter. Ergosterol concentration appeared as the strongest constrictor of inhibitory effects of litter on understory species. The results of this study contribute to the understanding of the net effect of fresh and decomposed litter from exotic and native trees on the growth of understory species. Image, graphical abstract • Phytotoxic effects of leaf litter from exotic and native trees predominate over positive effects on the growth of understory herb species. • Leaf litter from exotic tree species did not exert a more negative effect on the growth of understory herb species than litter from native trees, not supporting the Novel Weapons Hypothesis. • The concentration of total phenolics and flavonoids of litter decreased while acid detergent fiber, lignin and ergosterol increased as litter age increased. • Ergosterol concentration was the strongest constrictor of inhibitory effects of litter on understory species. [ABSTRACT FROM AUTHOR]

β-cyclocitral is a volatile short-chain apocarotenoid generated by enzymatic or non-enzymatic oxidation of the carotenoid β-carotene. β-cyclocitral has recently emerged as a new bioactive compound in various organisms ranging from plants and cyanobacteria to fungi and animals. In vascular plants, β-cyclocitral and its direct oxidation product, β-cyclocitric acid, are stress signals that accumulate under unfavorable environmental conditions such as drought or high light. Both compounds regulate nuclear gene expression through several signaling pathways, leading to stress acclimation. In cyanobacteria, β-cyclocitral functions as an inhibitor of competing microalgae and as a repellent against grazers. As a volatile compound, this apocarotenoid plays also an important role in intra-species and inter-species communication. This review summarizes recent findings on the multiple roles of β-cyclocitral and of some of its derivatives. • β-cyclocitral is a volatile oxidation product of the carotenoid β-carotene. • β-cyclocitral is found in a large variety of living organisms ranging from cyanobacteria and plants to fungi and animals. • β-cyclocitral can be converted in vivo into various derivatives including β-cyclocitric acid. • β-cyclocitral and β-cyclocitric acid are plant signals triggering defense mechanisms against environmental stresses. • β-cyclocitral and its derivatives also function as allelochemicals and repellents in non-vascular plants and in animals. [ABSTRACT FROM AUTHOR]

• In vitro Streptocarpus plantlets excreted quinones into their growth medium from leaflet bases, petiolodes and roots. • Extracts of growth medium inhibited radish seed germination in a concentration-dependent manner. • (±)-Dunnione is considered to affect germination through redox-cycling and ROS production. • Actions of (±)-dunnione appeared bi-phasic: low concentrations (<25 g) being anti-oxidant and high concentrations (>>125 g) pro-oxidant. Mature plants of S. dunnii Hook. f. produce naphthoquinones in aerial structures and anthraquinones in roots. Immature in vitro -cultured plantlets of Streptocarpus dunnii and S. × hybridus 'Ruby' (Gesneriaceae) excrete orange-red metabolites into their growth media ('artificial' rhizosphere). Our objectives were to: (i) extract and identify excreted compounds; (ii) determine the phytochemical effects of prolonged micropropagation and (iii) examine if excreted compounds affected seed germination. Results demonstrated that both Streptocarpus plantlets excreted complex mixtures of naphtho- and anthraquinones from around leaflet bases, petiolodes and fibrous roots. Chemical analyses showed (±)-dunnione as the main naphthoquinone, even after prolonged micropropagation. A TLC-based bioassay and a replicated, multifactorial, concentration-dependent experiment, found radish seed germination was inhibited in a concentration-dependent manner. 'Low' (±)-dunnione (25 μg) concentrations delayed germination for 2 days, with higher (125 μg) concentrations producing longer, but still transient, delays, i.e. not high enough to inhibit germination. (±)-Dunnione exerts its effects through redox cycling and ROS production. Since ROS production is essential for triggering germination, low concentrations were considered antioxidant reducing ROS production in seed coats and embryos thereby delaying germination, while higher concentrations were pro-oxidant, creating oxidative stress and poor seedling growth. Our results suggest that effects on seeds are biphasic and concentration-dependent. The significantly greater inhibitions in germination produced with whole medium extracts were attributed to higher (±)-dunnione levels in combination with other bioactive quinones. Since (±)-dunnione is also fungitoxic, we conclude that it acts an allelochemical protecting developing Streptocarpus plantlets from fungal attack and together with other excreted quinones can inhibit germination of seeds from competitor plants. [ABSTRACT FROM AUTHOR]

• Phytocompounds from Eugenia uniflora are promising sources of compounds with cytoprotective effect; • The cytoprotective effect is caused, mainly, by chelating and antioxidant mechanism; • This effect can be related with the antioxidant activity of phytocompounds, mainly the flavonoids. This study aims to verify the chelating, antioxidant and cytoprotective activities of Eugenia uniflora in a eukaryotic and prokaryotic model. Ethanolic extract, as well as tannic and flavonoid fractions, were prepared from samples obtained from the species which were analyzed by LC-MS. The antioxidant activity through the FRAP method showed that the tannic fraction had the lowest EC 50. The suggested compounds identified in the extract and fractions were quercetin and the derivatives, myricetin, gallic acid, vanillic acid, quinic acid and catechin. Regarding the flavonoid fraction, a reduction in the fungicidal effect was observed. When the ethanolic extract was assayed in the presence of mercury chloride, all fractions showed a cytoprotection in relation to this metal. The sub-allelopathic concentration used was 64 μg/mL. The flavonoid fraction showed cytoprotective activity against aluminum for caulicles and radicles, whereas for the mercury against the radicles at all concentrations. Meanwhile the tannic fraction against aluminum showed a better development in the size of the radicles, the mercury there were differences in the sizes of the radicles and caulicles. The results demonstrated in this work indicate that natural products of Eugenia uniflora are promising sources of natural products with antioxidant and chelating activity. [ABSTRACT FROM AUTHOR]

• Bioherbicidal potential of thirteen local fig cultivars was assessed. • The high phytotoxic properties were revealed in leaf rather than in twig extracts. • Phytochemical profiles were significantly different among cultivars. • Significant correlations revealed between phytotoxicity and phenolic compounds. • Fig cultivars can be characterized and clustered in three groups. The phytotoxic effect of some tree species could act as an ecological filter through chemical production that influences plant growth of other species. Despite this widespread interest, few studies have investigated the allelopathic effect of some Moraceae species, while this mechanism has not been studied in Ficus carica. To address this research, we attempted to identify the allelopathic mechanisms of thirteen local preserved fig cultivars on the germination and seedling growth of common weeds and standard target species. The results stated that all fig extracts displayed significant phytotoxic impact, and the degree of inhibition was appeared to be dependent on the cultivars and target species. In general, leaf extracts were more toxic and significantly influenced the seedling elongations, as compared to twig extracts. It was clearly marked that the germination and growth of weed species were totally affected by leaf aqueous and methanol extracts of cultivars Kahli and Bouhouli, respectively, at 40 g/L and 6 g/L. The phytochemical analysis through high performance liquid chromatography detected similar profile among cultivars but with a significant disparity in phenolic composition. Among the identified compounds, rutin is the major flavonoid compound recorded in cv. Zidi and was highly accumulated in leaf rather than in twig. It was obvious that the different fig cultivars or even their tissues can be characterized and clustered in three groups based on their allelopathic potential and phenolic compounds. [ABSTRACT FROM AUTHOR]

Allelopathy is a biochemical interaction between plants in which a donor plant releases secondary metabolites, allelochemicals, that are detrimental to the growth of its neighbours. Traditionally considered as bilateral interactions between two plants, allelopathy has recently emerged as a cross-kingdom process that can influence and be modulated by the other organisms in the plant's environment. Here, we review the current knowledge on plant–interkingdom interactions, with a particular focus on benzoxazinoids. We highlight how allelochemical-producing plants influence not only their plant neighbours but also insects, fungi, and bacteria that live on or around them. We discuss challenges that need to be overcome to study chemical plant–interkingdom interactions, and we propose experimental approaches to address how biotic and chemical processes impact plant health. Plants make use of secondary metabolites to communicate with their environment. Allelopathic plants release secondary metabolites to gain a competitive advantage over other plants. Grassy crops release benzoxazinoid compounds, which impact plants, animals, and microbes. Plant–interkingdom interactions, in particular those with soil-dwelling organisms, are key factors in plant health and fitness. Recent findings indicate that research on how allelopathic compounds modulate plant fitness in natural settings needs to integrate interkingdom interactions. [ABSTRACT FROM AUTHOR]

Vermicompost derived exclusively from ipomoea (Ipomoea carnea), a weed notorious for its toxic and allelopathic characteristics, was explored for its potential use as an organic fertilizer. Ipomoea vermicompost (IVC) at four levels (0, 2.5, 3.75, and 5 tonnes/ha) was explored for its effect on the germination, growth and fruition of ladies finger (Abelmoschus esculentus) in appropriately replicated experiments. It was seen that IVC encouraged the germination and growth of ladies finger at all levels of the IVC application, and best results were obtained in 5 t/ha treatments. The positive effect occurred at all stages of A.esculentus cultivation ─ from germination of its seeds to all the vegetative growth phases and the fruit yield. There was also improvement in the quality of fruits in terms of mineral, protein and carbohydrate contents, and reduction in the disease incidence and pest attacks, due to the IVC application. The studies reveal that vermicomposting enables ipomoea to acquire all the qualities of a good organic fertilizer with simultaneous loss of its toxicity and allelopathy. The findings raise hopes that the enormous quantities of ipomoea biomass that is generated across the world, and which presently goes to waste, may become utilizable in producing organic fertilizer. [ABSTRACT FROM AUTHOR]

The present study intended to investigate the effect of aqueous extract from Calotropis procera L. on growth of wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and some pathogenic microorganisms (Escherichia coli L. and Staphylococcus aureus R.) by the laboratory experiments. Also, phytochemical screening of aqueous extract of C. procera was qualitatively tested for the presence of some bioactive compounds (alkaloids, phenolics, flavonoids, tannins, saponins, sterols and terpenoids). Results showed that higher concentrations of C. procera extract (7% and 10%) significantly reduced germination percentage, radicle length and plumule length of wheat as compared to control. In contrast, the aqueous extract had not effect on seed germination percentage of barley but had a great inhibition effect on length of radicle and plumule. Also results showed that aqueous extract of C. procera effect on the pathogenic microorganisms Escherichia coli L. and Staphylococcus aureus R. in which there was a marked increase inhibition in growth of two microorganisms with the higher concentration. The main component of C. procera may be phenolics compound and flavonoids that may be responsible for their action on seed germination of the studied plants and growth of two tested microorganisms. [ABSTRACT FROM AUTHOR]

• Anabaena crude extract and laxaphycin B decrease larval survivorship and settlement. • Laxaphycins A and B interact to reduce coral larval survival and settlement. • In situ laxaphycin concentrations close to Anabaena are sufficient to inhibit coral recruitment. • Benthic cyanobacterial mats could be a cause of coral recruitment failure through allelopathy. Benthic cyanobacterial mats (BCMs) are becoming increasingly abundant on coral reefs worldwide. High growth rates and prolific toxin production give them the potential to cause widespread coral recruitment failure through allelopathic effects, but few studies have made the link between their toxicity for coral larvae and in situ toxin concentrations. Here we investigated the allelopathic effects of the benthic cyanobacterium Anabaena sp.1 on larvae of the coral Pocillopora acuta. This cyanobacterium produces several non-ribosomal cyclic lipopeptides of the laxaphycin family with cytotoxic properties. Therefore, we measured the concentration of laxaphycins A and B in Anabaena mats and in the water column and tested their effects on coral larvae. We found that Anabaena crude extract reduces both larval survivorship and settlement and that laxaphycin B reduces settlement. When larvae were exposed to both laxaphycins, there was a reduction in both larval survival and settlement. In the natural reef environment, laxaphycin A and B concentrations increased with increasing proximity to Anabaena mats, with concentrations being consistently above LC 50 and EC 50 thresholds within a 1 cm distance of the mats. This study demonstrates that laxaphycins reduce the survival and inhibit the settlement of coral larvae at concentrations found near Anabaena mats in situ. It further shows a combined effect between two cyanobacterial metabolites. As BCMs become more common, more of their secondary metabolites might be released in the water column. Their occurrence will lead to a reduction in coral recruitment rates, contributing to the continuing decline of coral reefs and shift in community structure. [ABSTRACT FROM AUTHOR]

Plants are able to actively detect and respond to the presence in neighboring plants, in order to optimize their physiology to promote survival and reproduction despite the presence of competing organisms. A key but still poorly understood mechanism for neighbor detection is through the perception of root exudates. In this review, we explore recent findings on the role of root exudates in plant–plant interactions, focusing both on general interactions and also the highly specialized example of root parasite–host plant interactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cladophora glomerata secretes phenolic compounds to the environment. • The phenolic compounds have impact on the communities of periphytic diatoms. • GAMs were applied to epiphytic diatoms. • Diatom species sensitive and insensitive to phenolic compounds were identified. Cladophora glomerata is the main macroalgae species responsible for the appearance of large mass compact algae formations, known as mats, in the fresh water of Lake Oporzynskie and the river Nielba, in western Poland. The mats are usually created by single species. In order to achieve seasonal domination, the algae secrete to the environment the allelopathic substances, which are phenolic compounds. In the period of intensive population growth, the thread-like thalli of these algae are richly incrusted with epiphytic diatoms. The amount of the secreted phenolic compounds changes in time within the vegetation period and depends on the weather conditions. The most abundant secretion of phenolic compounds takes place in July when, with increasing concentration of phenolic compounds in water, their content in the cells decreases. The main aim of the study was to establish the effect of the phenolic compounds secreted by C. glomerata thalli on the diatoms growing on them. According to our results, polyphenolic compounds have an impact not only on the abundance of diatom communities, but also on the structure of their communities. With increasing concentration of polyphenols, the abundance of Achnathidium minutissimum, Gomphonema olivaceum, Cocconeis pediculus, Navicula tripunctata decreased, while that of Amphora ovalis, Navicula rostellata, Staurosira construens, Cymbella lange-bartelotti increased. The species Cocconeis placentula reached domination thanks to the favorable influence of the environment and the effect of polyphenols secreted by the macroalgae. The variation in the diatom communities' structure was proved to also depend on the habitat parameters, mainly: EC, Turbidity, N-NH 4 , N-NO 3 , TDS. [ABSTRACT FROM AUTHOR]

Twenty-nine accessions of two buckwheat species (Fagopyrum esculentum Moench (common buckwheat) and Fagopyrum tataricum (L.) Gaertn. (Tartary buckwheat) were evaluated for their allelopathic potential against two resistant weeds, the monocot Lolium rigidum Gaud. and the dicot Portulaca oleracea L. The bulking use of synthetic herbicides and their consequent contamination of the environment and resulting increment of herbicide-resistant weeds, imminently requires a solution to achieve sustainable weed management without chemical inputs. The results obtained in this study suggest that buckwheat accessions can sustainably manage weeds through plant interference as competition or allelopathy. This research showed that accessions differ in their potential for sustainably managing both weeds with F. esculentum accessions being more effective against L. rigidum and F. tataricum accessions against both, monocot and dicot weeds. The chemical profile of buckwheat accessions was evaluated to know the content of polyphenols in common and Tartary buckwheat accessions and to know more about their ability to manage weeds sustainably. Differences in the chemical profile between the two buckwheat species were clear. While common buckwheat accessions showed more orientin, vitexin and hyperoside, Tartary buckwheat accessions had higher amounts of rutin, quercetin and kaempferol. We propose that the screening and selection of accessions with strong polyphenol content and vigorous growth can be a step towards organic farming due to its relation to the weed management. [Display omitted] • Buckwheat varieties differ in their allelopathic potential against weeds. • Common and Tartary buckwheat accessions differ in their flavonoid profile. • Buckwheat accessions with good flavonoid profile can sustainably manage weeds. • Traits as enhanced polyphenol content and growth are desired for organic farming. [ABSTRACT FROM AUTHOR]

• Ecotoxicology often uses standard genotypes of plants in testing. • We tested the influence of clonal variation in duckweeds on their response to common cyanotoxin, microcystin-LR. • Microcystin impacts were often masked by genotypic variation in response. • Results imply that genotype identity may be important to bioremediation and local evolutionary dynamics. Cyanotoxins produced by harmful cyanobacteria blooms can damage freshwater ecosystems and threaten human health. Floating macrophytes may be used as a means of biocontrol by limiting light and resources available to cyanobacteria. However, genetic variation in macrophyte sensitivity to cyanotoxins could influence their suitability as biocontrol agents. We investigated the influence of such intraspecific variation on the response of two rapidly growing duckweed species, Lemna minor and Spirodela polyrhiza , often used in nutrient and metal bioremediation. We assessed two biomarkers related to productivity (biomass and chlorophyll A production) and two related to fitness measures (population size and growth rate). Fifteen genetic lineages of each species were grown in media containing common cyanotoxin microcystin-LR at ecologically relevant concentrations or control media for a period of twelve days. Genotype identity had a strong impact on all biomarker responses. Microcystin concentration slightly increased the final population sizes of both macrophyte species with a marginal effect on growth rate of L. minor and the chlorophyll A production of S. polyrhiza, but overall these species were very tolerant of microcystin. The strong tolerance supports the potential use of these plants as bioremediators of cyanobacterial blooms. However, differential impact of microcystin exposure discovered in single lineage models among genotypes indicates a potential for cyanotoxins to act as selective forces, necessitating attention to genotype selection for bioremediation. [ABSTRACT FROM AUTHOR]

Consecutive monoculture regimes lead to the emergence of soil-borne diseases, which in turn impair plant growth and soil health, and restrict sustainable agricultural production. Biochar and plant growth-promoting bacteria (PGPBs) amendment in soil is considered a potential strategy for reducing soil-borne diseases. However, the combined effects of biochar and PGPBs on plant microbiomes and the subsequent consequences on plant performance remain largely unexplored. Here, we investigated the mechanisms on how biochar and biochar combined with a Bacillus synthetic community (SynCom) alleviated replant disease in Radix pseudostellariae by modulating rhizosphere soil protistan and plant microbial communities based on lab and field experiment. First, we found that biochar with Bacillus SynCom treatment increased the abundance of beneficial Bacillus spp. and Pseudomonas spp. after exposure to Fusarium oxysporum. Field experiments showed that biochar alone and combined with Bacillus SynCom improved the physiological traits and main components of Radix pseudostellariae. Besides, we found both two treatments increased Bacillus abundances in the root and soil, and significantly decreased Fusarium oxysporum density in the three compartments. Last, we validated that the combined treatment significantly decreased the relative abundance of pathogenic Ralstonia , promoted the abundance of Bacillus in the root and Paenibacillus in the leaf, and increased the abundance of the predatory protists Cercomonas and Paracercomonas in the soil. In addition, the combined amendment significantly increased the relative abundance of parasitic protists and decreased the plant pathogens. Meanwhile, the abundance of soil parasitic protists exhibited a significantly negative relationship with F. oxysporum density, and positive relationship with Bacillus density. Especially, soil pH and NO 3 −-N had a significantly indirect and positive effect on the parasitic protists and biomass by influencing bacterial richness of R. pseudostellariae leaf and root. Overall, our results revealed that amendment with combined biochar and Bacillus SynCom efficiently improved soil-borne disease suppression and plant physiological parameters by remodeling the plant and rhizosphere microbiome. This study provides a practical basis for more sustainable agriculture by promoting plant health through the modulation of plant and soil microbiomes. [Display omitted] • Biochar with PGPBs recruit some beneficial plant microbiota and specific predatory protists. • Biochar and PGPBs stimulated specific microbial taxa that enhanced suppression of fungal pathogens. • Soil parasites protists were negatively correlated to F. oxysporum and positively correlated to beneficial Bacillus. [ABSTRACT FROM AUTHOR]

This study investigated the poorly known phenomenon of Centimetric circular areas Uncolonized by Microbial Biofilms (CUMBs) which is frequently observed on natural and heritage stone surfaces displaying widespread lithobiontic colonization. In order to unveil a possible relationship with past lichen colonization, analyses were carried out on the distribution, morphometry, physical and mineralogical properties, and microscopic features of CUMBs on the marble surfaces of a balustrade in the Garden of a Savoy residence in Torino (Italy; UNESCO-WHS 823bis) and in its original quarry site in the W-Alps. Image analyses of CUMBs displayed a distributional and dimensional compatibility with lichen thalli (re-)colonizing surfaces in their vicinity. Invasive analyses on quarry materials displayed similar microscopic modifications in marble layers beneath CUMBs and lichens, associated to a higher stabilization of the calcite {01–12} form, which is favoured by the presence of organic substances. These findings support the hypothesis of a lichen origin for some CUMBs, which may derive from the modification of physical stone properties and/or a long-lasting allelopathic effect affecting surface bioreceptivity. [Display omitted] • CUMBs and lichens compared on natural and heritage marble surfaces. • Distributional and dimensional compatibility of CUMBs and lichens. • Similar micro-features beneath CUMBs and lichens associated to calcite reprecipitation. • Experimental evidences pointing to a lichen origin of (some) CUMBs. • Reduced CUMBs bioreceptivity due to modified physical properties and/or allelopathy. [ABSTRACT FROM AUTHOR]

Continuous cropping obstacles (CCO) refer to abnormal crop growth resulting from consecutive cultivation of related crops in the same soil. Panax notoginseng is severely affected by CCO. Crop rotation is the most effective approach to alleviate CCO. This study examined the impact of eight crop rotations on soil fertility, crop photosynthetic physiology, yield, and autotoxic substance levels in subsequent P. notoginseng crops. The findings indicate that maize is the most suitable rotational crop for P. notoginseng , significantly reducing saponin content by 18.5% and increasing biomass and chlorophyll content by 32.8% and 46.3%, respectively. Correlation analysis revealed that ginsenoside R1 enhances antioxidant enzyme activity, while saponin-like autotoxic substances are negatively correlated with chlorophyll. In conclusion, allelopathic autotoxicity primarily impairs plant growth by inhibiting photosynthesis and inducing changes in antioxidant system activity, leading to cell structure damage. Introducing maize in crop rotation reduces autotoxic substance levels and increases P. notoginseng biomass. [Display omitted] • Maize rotation may mitigate Panax notoginseng self-toxicity, then alleviate CCO. • Allelopathy hinders plant growth via photosynthesis inhibition and antioxidant. • The autotoxicity of ginsenoside R1 is related to the metabolism of ROS. [ABSTRACT FROM AUTHOR]