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• Types of bioactive metabolites and their role in plant growth and stress tolerance. • Plants terpenes are the largest group of secondary metabolites that play an important role in defense mechanisms against the herbivores and pathogens. • Impacts and role of secondary metabolites during biotic and abiotic stresses. • Role of microorganisms in altering plant metabolome under various environmental stresses. Primary metabolites are ubiquitous in nature and actively involved in growth while secondary metabolites (SMs) are involved in interaction with the environment. In plants terpenes are the largest group of secondary metabolites that play an important role in defense mechanisms against the herbivores and pathogens. Plant secondary metabolites such as alkaloids, phenolics and diterpenes have a great potential against many carcinogens. Carotenoids provide photoprotection and act as a pigment to absorb light during photosynthesis. Carotenoids are also efficient in the interaction with other organisms as they are phagostimulant and allelopathic agent. Flavonoids from the higher plants play a significant role in ultra-violet (UV) filtration, nitrogen fixation, floral pigmentation, and defense mechanisms against many diseases. These secondary metabolites provide protection to plants in a different type of biotic and abiotic stresses. Microorganisms also contain a high number of bioactive metabolites but not all of them. Marine microorganisms are a rich source of secondary metabolites such as alkaloids, terpenoids, polyketides, isoprenoids and non-isoprenoid and quinones amongst others. These metabolites are anti-inflammatory, anti-bacterial and anti-tumor in action. Secondary metabolites from fungi have a great therapeutic value as they have antifungal and antibacterial activity against many pathogens. Plant growth promoting rhizobacteria (PGPR) and Plant growth regulators (PGR) are the key biological entities to enhance the production of bioactive secondary metabolites in plants and can change the plant metabolome in response to various environmental stresses. This review paper will provide a new insight about the role of secondary metabolites in plant defense and the role of microorganisms in modulating the plant metabolome under various environmental stresses and their interactions with other microorganisms and plant growth regulators. [ABSTRACT FROM AUTHOR]

• Alexandrium monilatum is capable of allelopathy on other phytoplankton species. • The intensity of allelopathic effects varies with different strains of A. monilatum. • Goniodomins are likely not responsible for allelopathic activity in this study. • A. monilatum immobilizes M. polykrikoides , a co-occurring dinoflagellate. Species of the dinoflagellate genus Alexandrium can release bioactive extracellular compounds with allelopathic effects (e.g., immobilization, inhibition of growth, photosynthesis or lysis) towards other phytoplanktonic organisms. In the lower Chesapeake Bay, Virginia, US, succession or co-occurrence of blooms of Akashiwo sanguinea, Margalefidinium polykrikoides and the goniodomin-producing A. monilatum tend to be common during summer months, however the allelopathic potential of A. monilatum , and how it may affect bloom dynamics, has not be studied. We used a rapid fluorescence-based bioassay as well as flow cytometry and an assessment of immobilization to determine the potential effects of A. monilatum culture supernatants on M. polykrikoides, A. sanguinea and the diatom Chaetoceros muelleri (included as a reference strain). In addition, we also investigated the effects of standards of known A. monilatum toxins goniodomin A (GDA) and GDA seco-acid (GDA-sa). Exposure of C. muelleri to culture supernatants from two different strains of A. monilatum resulted in an inhibition of the maximum quantum yield of the photosystem II (F v /F m) and cell lysis of the diatom, with strain-specific variation observed, highlighted by a 30-fold difference in the effective concentration resulting in 10 % inhibition (EC 10) and 2-fold difference in the lethal concentration resulting in 50 % mortality (LC 50) between the two A. monilatum strains tested. Exposure of M. polykrikoides to A. monilatum culture supernatants resulted in a decrease in motility (at ≥ 500 eq. cells mL-1) along with a decrease in F v /F m (at ≥ 1,500 cells mL-1) and altered cellular morphology (at ≥ 3,500 eq. cells mL-1). No effect was observed when A. sanguinea was exposed to A. monilatum culture supernatants (at the concentrations tested in these studies). When M. polykrikoides was exposed to the GDA standard, its F v /F m (at ≥ 1,951 nM) and motility (at ≥ 390 nM) decreased, and its morphology (at ≥ 975 nM) was modified. The study of supernatant time- and temperature-stability, and the absence of a relationship between observed effects and goniodomin concentrations suggested the presence of additional unknown allelochemicals distinct from goniodomins, as has been observed for other Alexandrium species. Immobilization of M. polykrikoides by A. monilatum culture supernatants and GDA standard in laboratory-based exposure experiments may indicate that A. monilatum has a competitive advantage when both species co-occur in the Chesapeake Bay and this warrants further testing. [ABSTRACT FROM AUTHOR]

• Alien Acacia melanoxylon germination is not inhibited by leachates of itself or a common Afrotemperate Forest overstorey species. • Acacia melanoxylon showed high viability (90%) and an average germination rate of 67%. • The insensitivity of Acacia melanoxylon to allelopathic leachates likely facilitates it establishment in Southern Cape Afrotemperate Forest. The invasive alien tree species Acacia melanoxylon R. Br has been known to invade some forest ecosystems in Europe through allelopathy (amongst other mechanisms) which allows a competitive advantage over indigenous species. Acacia melanoxylon is widespread in Southern Cape Afrotemperate Forest, South Africa, and may establish successfully in these forests in certain contexts. In a nursery trial we compared the allelopathic potential of phyllode or leaf leachates of Acacia melanoxylon and a common overstorey indigenous species, Olea capensis L. macrocarpa C.H. Wright on the germination of seeds of Acacia melanoxylon. We compared the germination of Acacia melanoxylon seeds among three treatments, namely Acacia melanoxylon leachate, Olea capensis macrocarpa leachate, and no leachate. Stain-testing of seeds showed high viability (90%). The average germination of Acacia melanoxylon was 67% and there was a marginally significant difference in the number of germinants between the three treatments (H= 6.16; df= 2; P = 0.04). Pairwise multiple comparisons of ranks revealed that germination was marginally higher under Acacia melanoxylon leachate treatment than the control (Z = 1.97; df = 2; P = 0.14), and marginally higher under Olea capensis macrocarpa leachate than the control (Z = 0.12; df = 2; P = 0.12). This suggests that germination of Acacia melanoxylon is improved, or at the least, unaffected, by allelopathic substances of itself or of a common Afrotemperate Forest overstorey species. We concluded that the lack of sensitivity of Acacia melanoxylon germination to allelopathic substances of itself or a common indigenous overstorey species likely contribute to its successful establishment in Southern Cape Afrotemperate Forest. [ABSTRACT FROM AUTHOR]

Sesquiterpene lactones (SL) are allelopathic compounds that demonstrate great potential of use in sustainable weed management. In this study, membrane processing technology was used for ethanolic Cynara cardunculus leaves extract (CcLE) ultra- and nanofiltration to produce SL-enriched fractions with increased phytotoxic activity. Experiments were conducted to select an ultrafiltration membrane (DuraMem500, DuraMem900 and SuezGH2000) for SL recovery and high molecular weight compounds (MWC) removal. SuezGH2000, which had rejection percentage of 50 % and 88 % for cynaropicrin (Cyn) and chlorophyll, respectively, was used for a sequential purification along with DuraMem200 for lower MWC removal. Since Cyn content on initial feed (11.9 %) and permeate (11.2 %) were similar, as well as phytotoxic activity, the results suggested that DuraMem200 was unsuitable for CcLE fractionation. SuezGH2000 revealed a slight increase on SL content, so, the permeation profile and enhancement of SL content were evaluated. An increase on SL content (36.0–71.0 %) was obtained after 2.3 diavolumes, followed by a decrease between 2.6 and 4.7 diavolumes. Phytotoxic activity evaluations revealed a direct association with SL content with enhancement of activity, particularly at inhibiting shoot growth of Portulaca oleracea. This study revealed SuezGH2000 effectiveness on SL purity improvement on CcLE fractions after 2.3 diavolumes and its potential to be used as a bioherbicide active component. • Enriched fractions were obtained through membrane processing technology. • Suez™GH showed better separation between cynaropicrin and chlorophylls. • Suez™GH enhanced sesquiterpene lactones content from 36 % to 71 %. • Enriched fractions showed enhanced phytotoxic activity against Portulaca oleracea. [ABSTRACT FROM AUTHOR]

Bacterial wilt disease poses a significant threat to the production and quality of tobacco. Disease-resistant varieties of tobacco are the primary means of preventing bacterial wilt, but the soil microbial mechanisms that alleviate this disease require further in-depth research. In our study, we analyzed the physicochemical and microbial properties of rhizosphere soil in four different disease-resistant varieties of tobacco. The treatments included: T1 (Chang Bo Huang; 100 % infection rate); T2 (Yun Yan 87; 80 % infection rate); T3 (K326; 50 % infection rate) and T4 (YAN YAN 97; 0 % infection rate). Our results showed that the T4 treatment improved the fresh biomass of tobacco by 35.42 % compared to the T1 treatment. In addition, a significant increase in soil pH and soil organic matter (SOM) from 4.98 and 1.24 % under T1 treatment to 5.86 and 1.38 % under T4 treatment, respectively. As the disease resistance of the tobacco variety improved was found, there was a noticeable upward trend in the number of operational taxonomic units (OTUs) in the rhizosphere soil, showing higher sensitivity compared to fungi. Additionally, rhizosphere soil from susceptible varieties exhibited higher levels of metabolites, resulting in the accumulation of acidic substances (6-aminopenicillanic acid, garcinia acid, and 4-decan-4-ylbenzenesulfonic acid). Moreover, these soil metabolites might have attracted certain pathogenic fungi (Monoblepharomycota), contributing to the spread of soil diseases. This study suggests that the rhizosphere soil of disease-resistant tobacco variety provides a better microecological environment which could inhibit accumulation of allelopathic substances and reduce the spread of bacterial wilt disease. [ABSTRACT FROM AUTHOR]

Alien invasive plant species of the genus Carpobrotus pose a major threat to coastal dune ecosystems. These human-introduced species have quickly expanded throughout the Mediterranean basin and other regions due to their high reproduction rates and adaptability. Carpobrotus invasion alters soil properties due to necromass and the release of allelopathic compounds, hindering the regrowth of native flora, with anticipated impacts on the native vegetation-associated soil microbial communities. While some studies have described changes in microbial communities between native and Carpobrotus -impacted areas, none have specifically addressed the responses of microbial communities associated with single native species. In this light, the bacterial and fungal communities specifically associated with different native species in both natural and Carpobrotus -impacted plots were examined in three locations along the middle Tyrrhenian Italian coast. Microbial communities responses to the Carpobrotus invasion varied greatly depending on the native species and the edaphic characteristics of the study locations. Microbial communities associated with Pancratium maritimum were the most affected ones and those associated with Cakile maritima the less sensitive to the invasion, which may be correlated to the different characteristics of these plant species. Furthermore, fungal communities exhibited a greater degree of disruption compared to bacterial ones. In invaded plots, fungal species that comprise plant pathogens were notably more abundant. This suggests that patterns in microbial communities response to this invasion phenomenon cannot be generalized, and that recovery strategies should consider various local conditions and be adjusted for the various native vegetation species. Finally, the possible spread of fungal plant pathogens as a mechanism of defence of Carpobrotus should be considered. [Display omitted] • Microbial communities associated with different native species were analyzed. • Microbial communities responses to invasion varied for different native species. • The responses varied in the study sites and were linked to edaphic conditions. • Fungal components of the communities are more affected than bacteria ones. • Carpobrotus invasion determines an increase of fungal plant pathogens. [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]

• Cyanobacterial blooms are an ecological and public health issue. • Bloom loss processes are less studied than bloom formation processes. • This review presents bloom loss processes and management implications. • We show bloom disappearance is controlled by complex biotic and abiotic processes. • We discuss challenges for predicting effects of climate change on loss processes. Cyanobacterial blooms present substantial challenges to managers and threaten ecological and public health. Although the majority of cyanobacterial bloom research and management focuses on factors that control bloom initiation, duration, toxicity, and geographical extent, relatively little research focuses on the role of loss processes in blooms and how these processes are regulated. Here, we define a loss process in terms of population dynamics as any process that removes cells from a population, thereby decelerating or reducing the development and extent of blooms. We review abiotic (e.g., hydraulic flushing and oxidative stress/UV light) and biotic factors (e.g., allelopathic compounds, infections, grazing, and resting cells/programmed cell death) known to govern bloom loss. We found that the dominant loss processes depend on several system specific factors including cyanobacterial genera-specific traits, in situ physicochemical conditions, and the microbial, phytoplankton, and consumer community composition. We also address loss processes in the context of bloom management and discuss perspectives and challenges in predicting how a changing climate may directly and indirectly affect loss processes on blooms. A deeper understanding of bloom loss processes and their underlying mechanisms may help to mitigate the negative consequences of cyanobacterial blooms and improve current management strategies. [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]

The need to reduce the use of chemical pesticides currently fosters great interest in eco-friendly biological control agents. In addition, the isolation of plant allelopathic substances and the evaluation of their phytotoxic effects can lead to the discovery of new natural herbicides. In this context, our study aimed to assess the herbicidal activity of ten crude extracts obtained from aerial parts of Tunisian spontaneous plants against Trifolium incarnatum, Silybum marianum and Phalaris minor. It confirmed that the Cynara cardunculus methanolic extract best inhibited weed germination and seedling growth, and caused necrosis or chlorosis. Following a bioassay-guided fractionation, five main phenolic compounds, (1) syringic acid, (2) p -coumaric acid, (3) myricitrin, (4) quercetin and (5) naringenin were identified in the most active crude methanolic extract. Then, only 3 of the flavonoids contained in the most active fraction were tested on Trifolium incarnatum. The 3 compounds had a significant phytotoxic effect and therefore could be employed in a new composition of botanical herbicides to control crop weeds. Besides, a novel herbicide composition was designed to improve the post-emergence activity of the methanolic extract. The formulation containing the C. cardunculus crude methanolic extract showed the same herbicidal activity as the standard industrial bioherbicide containing pelargonic acid. These results make C. cardunculus a suitable source of natural compounds potentially usable as natural herbicides. Image, graphical abstract • C. cardunculus extract had the best herbicidal activity among 10 plant extracts. • Five phenolic compounds were identified in C. cardunculus. • Myricitrin, naringenin and quercetin were the main active compounds in C. cardunculus. • Fraction 2 of C. cardunculus had the same herbicidal effect as biological herbicide. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • MFCs could remove three quinolones antibiotics efficiently. • Microbial activities of biofilms were greatly improved after acclimation. • Long-term operation of biofilms enhanced their anti-shock capacities. • The enrichment of functional microbes contributed to biodegrade ciprofloxacin. Abstract Few studies have focused on the feasibility of microbial fuel cells (MFCs) for removing quinolones antibiotics and their anti-shock capabilities. After 1.5 years of operation, the removal efficiency of 10 mg/L ciprofloxacin in MFCs increased to 99.00% in 88 h. These results are in accordance with the enhanced activity of biofilms and voltage output of MFCs. Additionally, the anti-shock capacities of the biofilms in MFCs were evaluated by treating ofloxacin and enrofloxacin and operating at different temperature and salinity. These MFCs can remove 87.31% and 40.81% of ofloxacin and enrofloxacin in 72 h, respectively. Even exposed to a low temperature of 10 °C or a salinity of 3%, the MFCs can achieve greater than 50% and nearly 80% of ciprofloxacin removal efficiency, respectively. The enrichment of Alcaligenes and Chryseobacterium contributed mostly to the removal of quinolones antibiotics. This study provides scientific evidences for treating wastewater containing quinolones antibiotics using MFCs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • MSNs can be loaded with multiple antibiotics, such as polymyxin B and vancomycin. • MSNs surface chemistry affects the adsorption and release kinetics. • MSNs-loaded antibiotics had stronger synergy and higher antimicrobial effect. • Using MSNs as carrier for antibiotics decreased the cytotoxicity of antibiotics. Abstract Treatment of polymicrobial infections requires combination therapy with drugs that have different antimicrobial spectra and possibly work in synergy. However, the different pharmacokinetics and adverse side effects challenge the simultaneous delivery of multiple drugs at the appropriate concentrations to the site of infection. Formulation of multiple drugs in nano-carrier systems may improve therapeutic efficacy by increasing the local concentration and lowering the systemic concentration, leading to fewer side effects. In this study, we loaded polymyxin B and vancomycin on bare and carboxyl-modified mesoporous silica nanoparticles (B-MSNs and C-MSNs, respectively) to achieve simulataneous local delivery of antibiotics against Gram-positive and –negative bacteria. Polymyxin B adsorbed preferentially to nanoparticles compared to vancomycin. The total antibiotic loading was 563 μg and 453 μg per mg B-MSNs or C-MSNs, respectively. Both B-MSNs and C-MSNs loaded with antibiotics were effective against Gram-negative and Gram-positive bacteria. The antibiotics had synergistic interactions against Gram-negative bacteria, and the antimicrobial efficacy was higher for antibiotic-loaded C-MSNs compared to free antibiotics at the same concentration even though the cytotoxicity was lower. Our study shows that formulations of existing antibiotics in nanocarrier systems can improve their therapeutic efficiency, indicating that combination therapy with drug-loaded silica nanoparticles may provide a better treatment outcome for infections that require high concentrations of multiple drugs. [ABSTRACT FROM AUTHOR]

With the increase of cultivated varieties of Chinese herbal remedies, the continuous expansion of cultivation area, and long–term monoculture cropping, the problems of soil diseases, yield loss and quality reduction are becoming increasingly aggravated. Continuous crop obstacle has been a limiting factor which strongly affects the yield and quality of Chinese herbal remedies. Various measures have been used to alleviate continuous crop obstacles, however, they have not been able to effectively address such problems. As a carbon-rich material, biochar can significantly improve soil quality which provides a promising way to alleviate continuous crop obstacles of Chinese herbal remedies. In this paper, we summarized the detriments and causes of continuous crop obstacles in Chinese herbs, and reviewed the agronomic measures and physicochemical control methods proposed to cope with such problems. The research progresses on the role of biochar in the alleviating continuous crop obstacle problems, including the improvement of soil properties and soil microbial community structure, inhibition of the self–toxic effect by allelochemicals of herbs were discussed. Future research on how biochar affects the allelopathic substances that secreted by Chinese herbal remedies should be conducted. This review will provide a theoretical basis and technical support on how to use biochar to mitigate the continuous crop obstacle of medicinal herbs. [Display omitted] • Mechanisms of Chinese herbal medicine's continuous cropping obstacles were elucidated. • Common methods used for alleviating continuous crop obstacle problems were discussed. • Role of biochar in alleviating continuous crop obstacles was elaborated. • Research outlooks on biochar's potential in continuous crop obstacle mitigation were proposed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • SFE and ESE technique were used to extract bioactive compounds from H. annuus leaves. • Fractionation of extracts using three separators was evaluated for both techniques. • High overall yields were obtained with ESE and adding water to the solvent system. • Fraction S3 using CO 2 +50% H 2 O was rich in potential allelopathic compounds. • 2 sesquiterpenes, 1 flavonoid and 1 lignan presented high inhibitory activity profiles. Abstract The allelopathic potential of Helianthus annuus L. leaves was study based on bio-directed chemical fractionation approach. Aerial parts of H. annuus were extracted by means of SFE using supercritical carbon dioxide (scCO 2) and ESE using CO 2 +50% EtOH/H 2 O (varying ethanol in water from 0 to 100%). Extractions were carried out at 400 bar, 55 °C, 20 g/min and for 4 h. Then, extracts were fractionated in three separators at the following conditions: S1: 200 bar/45 °C; S2: 90 bar/40 °C; and S3: 1 atm/30 °C. ESE obtained higher overall yields than scCO 2 and the use of water as cosolvent (CO 2 +50% H 2 O) resulted in a S3 fraction free from chlorophylls and rich in bioactive compounds. 14 compounds, including fatty acids, terpenes, flavonoids and heliannuols, were isolated from this fraction. After performing the bioassay on pure compounds, heliannuol D, tambulin, pinoresinol and sesquiterpene 10-oxo-isodauc-3-en-15-al showed the most effective inhibitor profiles. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • First comparison between biocides, allelopathic substances and UV-C treatments. • Environmentally friendly methods against photosynthetic biofilms. • UV-C treatment as a promising tool to combat biofilm proliferation. • Biofilm colorimetric and physiological parameters monitored after treatment. • Heterotrophic fungi colonization on necrotic matter after treatment. Abstract UV-C and biocide treatments are frequently used to treat historical monuments contaminated by autotrophic biofilms. In this study, the authors compare for the first time the efficacy of these treatments against microorganisms such as cyanobacteria and algae proliferating in the Vicherey church (Vicherey, Vosges Department, France). To identify the most environmentally friendly and also efficient method, an allelopathic treatment was also tested. Colorimetric and physiological measurements of treated biofilms were thus monitored for 6 months. Fungi growing on necrotic matter from treated biofilms were sampled and sequenced. With biocides, results showed incomplete eradication of biofilms, even after two treatments. Biofilm color loss was delayed in comparison to UV-C treatment, which appeared more efficient after just one treatment. Moreover, quantum yield (Fv/Fm) decreased immediately after UV-C treatment, indicating inhibition of algae and cyanobacteria photosynthesis. However, two species of fungi colonized the cyanobacteria biofilms treated with UV-C. Allelopathic treatment was not efficient on biofilm and showed no deleterious effect on photosynthesis. The present findings demonstrate that the UV-C method, coupled with a cleaning phase for necrotic organic matter, may be considered environmentally friendly and the best alternative to chemicals. [ABSTRACT FROM AUTHOR]

Widespread resistance in Phalaris minor is a major challenge for sustainable wheat production. Recently, multiple resistance and cross resistance in this weed increased the concerns of wheat growers. The use of potential integrated resistance management strategies including allelopathic crop mulches and herbicide mixtures is crucial in assuring sustainable production. A two-year field trial was conducted during 2014–15 and 2015–16 in wheat to evaluate the efficacy of allelopathic mulches of sunflower, rice, maize, and sorghum alone and in combination with three types of herbicide mixtures. Post-emergence herbicide mixtures used in this study were clodinafop –propargyl plus metribuzin, sulfosulfuron plus clodinafop-propargyl, and pinoxaden plus sulfosulfuron at 50% of recommended doses. Integrated use of allelopathic crop mulches and herbicide mixtures provided effective control of P. minor in wheat. However, application of allelopathic mulches and herbicide mixtures alone did not provide a satisfactory control of P. minor . In addition, the application of allelopathic mulches caused a significant decay (23–52%) of soil weed seed bank. The integrated use of mulches and herbicide mixtures consistently enhanced the wheat yield by 23–39% and 24–35% during 2014–15 and 2015–16, respectively. These findings, as the first indication of the potential integration of allelopathic mulches and post-emergence herbicide mixtures to manage P. minor in wheat fields, would help control resistant P. minor and delay further herbicide resistance in this weed. [ABSTRACT FROM AUTHOR]

Microcystis and Anabaena (Dolichospermum) are among the most toxic cyanobacterial genera and often succeed each other during harmful algal blooms. The role allelopathy plays in the succession of these genera is not fully understood. The allelopathic interactions of six strains of Microcystis and Anabaena under different nutrient conditions in co-culture and in culture-filtrate experiments were investigated. Microcystis strains significantly reduced the growth of Anabaena strains in mixed cultures with direct cell-to-cell contact and high nutrient levels. Cell-free filtrate from Microcystis cultures proved equally potent in suppressing the growth of nutrient replete Anabaena cultures while also significantly reducing anatoxin-a production. Allelopathic interactions between Microcystis and Anabaena were, however, partly dependent on ambient nutrient levels. Anabaena dominated under low N conditions and Microcystis dominated under nutrient replete and low P during which allelochemicals caused the complete suppression of nitrogen fixation by Anabaena and stimulated glutathione S-transferase activity. The microcystin content of Microcystis was lowered with decreasing N and the presence of Anabaena decreased it further under low P and high nutrient conditions. Collectively, these results indicate that strong allelopathic interactions between Microcystis and Anabaena are closely intertwined with the availability of nutrients and that allelopathy may contribute to the succession, nitrogen availability, and toxicity of cyanobacterial blooms. [ABSTRACT FROM AUTHOR]

Enzyme from Daucus carota root catalyzed Henry reaction of substituted benzaldehydes and nitromethane in phosphate buffer of pH 7 at 28 °C to afford β -nitroalcohols in excellent yields (up to 94%). [ABSTRACT FROM AUTHOR]

The chemosynthesis and potential as green herbicides of 4,8-dihydroxy-1-tetralone (4, 8-DHT) and its derivates were emphatically addressed in this study. Firstly, the synthesis of 4, 8-DHT from commercially available material 1, 5-dihydroxynaphthalene was carried out through a novel route of five reaction steps. Then, its five derivates including 4-benzoyl-8-hydroxy-1-tetralone, 4-(3-hydroxypropoxy)- 8-hydroxy-1- tetralone, 4-(2,3-dihydroxypropoxy)-8-hydroxy-1-tetralone, 4-hydroxy-8-(3-hydroxy propoxy) −1-tetralone and 4-hydroxy-8-(2,3-dihydroxypropoxy)-1- tetralone were prepared by modifying alcoholic and phenolic hydroxyl in C-4 and C-8 position of 4,8-DHT molecular structure. After that, these synthesized compounds were examined for their toxicity against six kinds of weeds ( Lolium perenne , Phalaris arundinacea , Elymus dahuricus , Cichorium intybus , Sorghum sudanense , and Trifolium repens ) in vitro. In general, high concentration could generally inhibit while low concentration might promote the growth of weeds. Among these compounds, 4-(3-hydroxypropoxy)-8 −hydroxy-1-tetralone and 4-hydroxy-8- (3-hydroxypropoxy) −1-tetralone showed significant phytotoxic activities against the six tested weeds, while 4-hydroxy-8-(2,3-dihydroxypropoxy) −1-tetralone was less toxic. For all the six tested weeds, E. dahuricus appeared the most sensitive to the treatments of 4, 8-DHT compounds. Hence, it has been suggested that variables including compound type and concentration as well as weed species should be seriously considered in order to develop and utilize the group of 4, 8-DHT compounds as herbicide in future. [ABSTRACT FROM AUTHOR]

Organic nutrient sources such as farmyard manure, sewage sludge, their biogas digestates or other animal by-products can be valuable fertilizers delivering organic matter to the soil. Currently, especially phosphorus (P) is in the focus of research since it is an essential plant nutrient with finite resources, estimated to last only for some more decades. Efficient utilization of organic P sources in agriculture will help to preserve P resources and thereby has the potential to close nutrient cycles and prevent unwanted P-losses to the environment, one of the major causes for eutrophication of water bodies. Unfortunately, organic P sources usually contain also various detrimental substances, such as potentially toxic elements or organic contaminants like pharmaceuticals as well as pathogenic microorganisms. Additionally, the utilization of some of these substrates such as sewage sludge or animal by-products is legally limited in agriculture because of the potential risk to contaminate sites with potentially toxic elements and organic contaminants. Thus, to close nutrient cycles it is important to develop solutions for the responsible use of organic nutrient sources. The aim of this review is to give an overview of the contamination of the most important organic nutrient sources with potentially toxic elements, antibiotics (as one important organic contaminant) and pathogenic microorganisms. Changes in manure and sewage sludge management as well as the increasing trend to use such substrates in biogas plants will be discussed with respect to potential risks posed to soils and water bodies. Some examples for abatement options by which contamination can be reduced to produce P fertilizers with high amounts of plant available P forms are presented. [ABSTRACT FROM AUTHOR]

Animal manure is a main reservoir of antibiotic residues and antibiotic resistance. Here, the effect of temperature on sulfonamide antibiotics (SAs), sulfonamide-resistant (SR) genes/bacteria was investigated by aerobically incubating swine and chicken manures at different temperatures. In swine manure, the SAs concentration declined with increasing temperature, with a minimum at 60 °C. In chicken manure, the greatest degradation of SAs was noted at 30 °C. The reduction of relative abundance of antibiotic resistance genes (ARGs) and sul -positive hosts in swine manure was more pronounced during thermophilic than mesospheric incubation; neither temperature conditions effectively reduced these parameters in chicken manure. The relationship between the residual levels/distribution profiles of SAs, ARGs ( sul1 , sul2 and intI1 ), cultivable SR bacteria and sul -positive hosts was further established. The antibiotic residual profile, rather than antibiotic concentration, acted as an important factor in the prevalence of ARGs and sul -positive hosts in manure. Corynebacterium and Leucobacter from the phylum Actinobacteria tend to be main carriers of sul1 and intI1 ; the relative abundance of sul2 was significantly correlated with the relative abundance of cultivable SR bacteria. Overall, differences in resistant bacterial communities also constitute a dominant factor affecting ARG variation. This study contributes to management options for reducing the pollution of antibiotics and antibiotic resistance within manure. [ABSTRACT FROM AUTHOR]

Pinus elliottii Engelm. (slash pine) is distributed along the maritime coast of Southern Brazil, where it shows invasive pattern and typical allelopathic features. Large quantities of needle litter are produced by pine trees, a biomass that is little explored in areas where this species is alien. Little is known about the dynamics of needle and litter phytochemical interactions, particularly in subtropical environments. To elucidate the full range of needle and litter allelopathic potential, the effects of litter (superficial and deep) and seasonally harvested fresh slash pine needles stored for different times were evaluated against lettuce, tomato and cucumber seeds and seedlings. Increasing concentrations (0%, 1%, 2%, 4%, and 8% w/v) of hot and cold aqueous extracts of needles and litter affected in different ways target plant development. Growth and germination inhibition were directly related to the highest extract concentrations (regardless of the season and mainly in hot water extracts) of needles. On the other hand, stimulatory effects of litter extracts on lettuce growth were observed. Growth and germination of cucumber and tomato were not affected by pine litter as substrate when compared to rice husk. The presumable high polarity and thermal stability of slash pine leaf biomass allelochemicals and their transient toxic effect or growth promoting impact suggest potential applications of this largely available biomass both as a biological herbicide and growth substrate in plant propagation. [ABSTRACT FROM AUTHOR]

Ostreopsis blooms regularly occur in many Mediterranean coastal areas in late summer-autumn. In the northern Adriatic Sea, Ostreopsis blooms affect diatom-dominated microphytobenthic communities. In this study, the effects of the filtrates of some diatom species, both benthic ( Tabularia affinis , Proschkinia complanatoides and Navicula sp.) and planktonic ( Thalassiosira sp. and Skeletonema marinoi ) on cell morphology, cytological features and growth of O . cf. ovata were investigated. Our results showed a marked decrease of O . cf. ovata growth when cells were exposed to all diatom filtrates tested. The highest inhibitions were observed for exposures to P. complanatoides and Navicula sp. filtrates (92.5% and 80%, respectively) and increased with the age of diatom culture. Moreover, a clear DNA degradation and abnormal forms of O. cf. ovata cells (83.8% of the total) were found at the highest concentrations using Navicula sp. filtrate after 10 days of the inoculum. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate the variability in the essential oil yield and chemical composition of Achillea millefolium L. (whole aerial-parts, leaves and inflorescence) grown in the subtropical region of north India during annual growth. The allelopathic, antibacterial, antifungal, and antiacetylcholinesterase activities of the oil were also examined. The essential oil yield varied due to harvesting stages and plant-parts processed (0.10–0.70%). The oils obtained from different stages and plant-parts were analysed using GC-FID and GC–MS. Altogether thirty-nine constituents, forming 93.0–97.8% of the total oil composition were identified. Major constituents of the oils were germacrene D (1.1–46.6%), sabinene (4.0–38.9%), borneol (4.7–24.9%), camphor (0.6–17.6%), α-pinene (0.8–11.7%), artemisia ketone (3.1–12.9%), chamazulene (0.8–9.6%), γ -cadinene (0.3–8.2%), and camphene (0.2–5.7%). Cluster analysis grouped overall compositions into six main groups based on their dominant components. It was observed that season of harvesting and plant-parts affect the essential oil yield and chemical composition of A. millefolium . The chemical composition of the examined essential oil was different from those described from other geographical origins. Moreover, this oil displayed a significant allelopathic activity. [ABSTRACT FROM AUTHOR]

Inflammatory bowel disease (IBD) may develop due to an immunogenic response to commensal gut microbiota triggered by environmental factors in the genetically susceptible host. Isotretinoin, applied in the treatment of severe acne, has been variably associated with IBD, but prior treatment with antibiotics, also associated with IBD development, confounds confirmation of this association. This study investigated the effects of doxycycline, metronidazole (frequently used in the treatment of acne and IBD, respectively) and isotretinoin on murine gut (faecal) microbiota after 2 weeks of treatment and after a 4-week recovery period. Faecal microbiota composition was assessed by 16S rRNA gene sequencing on the GS-FLX 454 platform with primers directed against the variable regions V1–V2. Doxycycline had a modest effect on bacterial richness and evenness, but had pronounced persistent and significant effects on the abundance of certain operational taxonomic units compared with the control group. In contrast, metronidazole induced a pronounced reduction in diversity after treatment, but these effects did not persist after the recovery period. This study demonstrates differential effects of antibiotics on the gut microbiota with doxycycline, unlike metronidazole, mediating long-term changes in the murine gut microbiota. Isotretinoin had no significant effect on the faecal microbiota. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) is one of the greatest threats to global health this century. The primary cause of AMR is antibiotic misuse, especially routine use of antibiotics for self-limiting illnesses. This study aimed to explore behaviours related to antibiotic use in university students across China. An electronic questionnaire was distributed at a major university in each of the six regions. A cluster random sampling method was adopted. The χ 2 test and logistic regression were used to assess the relationship between knowledge and behaviour. A total of 11,192 students completed the questionnaire. In the past month, 3337 students (29.8%) reported a self-limiting illness, of whom 913 (27.3%) saw a doctor, 600 (65.7%) of whom were prescribed antibiotics [190 (31.7%) by infusion]; 136 students (22.7%) asked for and received antibiotics. Of the 1711 students (51.3%) who treated themselves, 507 (29.6%) self-medicated with antibiotics. In the past year, 23.0% of students had used antibiotics as prophylaxis, 63.1% kept a personal stock of antibiotics and 56.0% had bought antibiotics at a drugstore (two-thirds without a prescription). Students with lower knowledge scores about antibiotics were significantly more likely to see a doctor, be prescribed with antibiotics, self-medicate with antibiotics, and use antibiotics prophylactically. This massive misuse of antibiotics for self-limiting illnesses by well-educated young adults is a serious concern. A national campaign is urgently required to address rational prescribing of antibiotics by doctors, enforce existing restrictions on over-the-counter sale of antibiotics, and educate the general public about antibiotics and the management of self-limiting illnesses. [ABSTRACT FROM AUTHOR]

Ethanol extract and fractions obtained from leaves of Smilax brasiliensis Sprengel were examined in order to determine their total phenolic and flavonoid contents, as well as antioxidant and allelopathic activities. Analysis by thin-layer chromatography suggested the presence of rutin in the ethanol extract and in the ethyl acetate and hydroethanol fractions. In addition, chlorogenic acid was present in the ethanol extract and in the dichloromethane, ethyl acetate and hydroethanol fractions. The antioxidant activity was significantly more pronounced for the ethanol extract and fractions than that of the commercial antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT). The allelopathic effect against the seeds of Allium cepa showed promising results, predominantly with effects in growth inhibition of hypocotyls and radicles at the lower concentration tested (125 μg mL − 1 ). The results of this study suggest that the extract and fractions obtained from S. brasiliensis could be used as natural antioxidants and herbicides. [ABSTRACT FROM AUTHOR]

The present study was undertaken to investigate the impact of UV-B radiation and benzoic acid (BA) on growth and metabolism of Solanum lycopersicum L. cv. Pusa ruby. Benzoic acid and UV-B radiation have impact on growth and development of Solanum . BA treatment in two concentrations 0.5 mM and 1.0 mM and UV-B alone and in combination (UV + BA) reduced root and shoot growth and biomass of the seedlings. BA with and without UV-B has negative impact on pigment, protein and sugar contents of the seedlings. Carotenoids showed varied responses to the stresses. BA decreased carotenoid content while UV-B increased the level of carotenoids. Lipid peroxidation and electrolyte leakage also increased under both stresses. Antioxidant enzyme activities significantly enhanced under BA treatment, but increase was further escalated when seedlings simultaneously exposed to UV-B radiation. It is evident that UV-B radiation enhanced the toxicity of BA in Solanum seedlings. [ABSTRACT FROM AUTHOR]

The effects of algal blooms on seaweeds have been rarely studied, although harmful algal blooms (HABs) are now normally regarded as worldwide incidents. In the present study, the effects of dense Karenia mikimotoi cells on the growth and photosynthesis of Hizikia fusiformis , a common and commercially cultivated macroalga in coastal waters of the East China Sea (ECS), were studied to understand the possible consequences when the mariculture encountered a dense harmful algal bloom. Furthermore, the counteraction of the latter on the growth and photosynthetic activities of K. mikimotoi was determined to evaluate the contribution of H. fusiformis commercial cultivation to environmental improvements. The results showed that the chlorophyll a (Chl a ) contents, maximal photochemical efficiency ( F v / F m ) and relative electron transfer rate (rETR) of gas vesicles (specialized leaves), adult and young receptacles of H. fusiformis were all significantly ( P < 0.05) inhibited compared with the mono-cultured ones. When compared with mono-cultured H. fusiformis (without K. mikimotoi ), the Chl a contents in gas vesicles, adult and young receptacles decreased by 20.6%, 17.6% and 33.2% within 2 weeks. Correspondingly, the F v / F m decreased by 7.9%, 37.4% and 43.7%; the apparent photosynthetic efficiency ( α ) decreased by 9.4%, 47.1% and 48.3%; and rETR decreased by 19.5%, 52.6% and 68.2%, respectively. The Chl a concentration of the mono-cultured K. mikimotoi (without H. fusiformis ) increased to 2247.97 μg l −1 from 958.11 μg l −1 within 14 d. Those of the co-cultivated ones (with H. fusiformis ), however, increased to 1591.31 μg l −1 on the 8th day and then decreased rapidly to 254.99 (±37.73) μg l −1 after the next 6 days. Furthermore, compared with the mono-cultured K. mikimotoi cells, the F v / F m , α and rETR max of co-cultivated ones decreased by 9.4%, 36.3% and 30.6%, respectively. The results indicated that the mature sporophytes of H. fusiformis were resistant to dense K. mikimotoi blooms and this resistance was organ-dependent as: gas vesicle > adult receptacles > young receptacles. On the other hand, commercial mariculture of H. fusiformis demonstrated the potential of preventing the occurrence of algal blooms. [ABSTRACT FROM AUTHOR]

Objective We aimed to evaluate factors associated with knowledge of antibiotics and drug resistance. Methods A questionnaire was handed out by 14 family physicians to their patients between December 20, 2014 and April 20, 2015 in Rethel (North-East of France). We conducted a cross-sectional study using a logistical regression model to assess factors associated with antibiotic knowledge. Three criteria were used to assess that knowledge. Results Overall, 293 questionnaires were analysed; 48% of patients had received antibiotics in the previous 12 months. Only 44% and 26% gave a correct answer for the statements “Antibiotics are effective against bacteria and ineffective against viruses” and “Antibiotic resistance decreases if the antibiotic use decreases”, respectively. Characteristics such as female sex, age > 30 years, high level of education, high professional categories, and having received antibiotic information by the media were associated with high level of knowledge about antibiotics and/or antibiotic resistance. In contrast, having received antibiotic information from family physicians was not associated with good knowledge. Conclusion Although media awareness campaigns had an independent impact on a higher public knowledge of antibiotics, the overall public knowledge remains low. It would be necessary to strengthen antibiotic campaigns with clearer information on the relation between the excessive use of antibiotics and the increased risk of antibiotic resistance. Family physicians should be more involved to improve antibiotic knowledge among target groups such as men, young patients, and people from a poor social and cultural background. [ABSTRACT FROM AUTHOR]

The interactions between invasive plants and their habitats may vary at different phases of the invasion process and depend on the phenotypic plasticity or local adaptations of each species. In this study, we investigated whether habitat changes during the invasion process are related to variations in the physiological traits (allelopathic properties) and genetic differentiation of daisy fleabane ( Erigeron annuus (L.) Pers.). E. annuus is a winter annual invasive species that originated in North America and is now distributed throughout Europe. Genetic and genotypic diversity analyses were performed for 37 populations of E. annuus based on inter simple sequence repeat (ISSR) polymorphisms. In total, 684 plants were analyzed; 342 were from stable habitats and 342 were from disturbed habitats. The genetic differences among the populations from the different habitats were studied using a Bayesian cluster analysis and an analysis of molecular variance (AMOVA) and by calculating the genetic and genotypic diversity parameters. A germination test using the juglone index was employed to examine the potential allelopathic properties of the plants from the different habitats. Bayesian cluster analysis, AMOVA and allelopathic effects evaluation revealed differences in the allelopathic potential and genetic structure of the E. annuus populations from the disturbed and stable habitats. This differentiation of populations could be associated with founder effects or with different selection pressures among habitats. [ABSTRACT FROM AUTHOR]

Allelopathic interactions among phytoplankton species are regarded as one of the important factors contributing to phytoplankton species competition and succession. The role and extent of allelopathic effects of blooming freshwater cyanobacteria on other phytoplankton species in eutrophied waters, however, are still unknown. We examined the allelopathic effect of Microcystis aeruginosa on two common green algae ( Scenedesmus quadricauda , Chlorella pyrenoidosa ) and a diatom ( Cyclotella meneghiniana ) by adding exudates from different growth phases and in co-culture tests. Exudates of M. aeruginosa from the exponential growth phase and the stationary phase significantly inhibited the growth of S. quadricauda , C. pyrenoidosa and C. meneghiniana , whereas those from the decline phase increased their growth. The presence of M. aeruginosa extremely inhibited the growth of all tested species in co-cultures within 24 h. Our results indicate that under the tested environmental conditions (25 °C, light 80 μmol quanta m −2 s −1 , manual shaking twice a day), allelopathic effects of M. aeruginosa on other phytoplankton species can significantly contribute to their competitive success. [ABSTRACT FROM AUTHOR]

Tecomella undulata is an ecologically and economically important tree in arid areas of southwestern Asia. It has important ornamental and medicinal uses. In this study, aqueous extracts from roots, leaves, inner stem barks and flowers of T. undulata were studied for their allelopathic effects on seed germination and early seedling growth of four important monocotyledonous and dicotyledonous ornamental plants. The flower and root extracts of T. undulata significantly (P<0.05) inhibited germination of tall fescue ( Festuca arundinacea Schreb.) and perennial ryegrass ( Lolium perenne L.) seeds, but leaf and inner stem bark extracts had no significant effects on either of these turf grasses. The allelopathic inhibition was greater for root extracts than flower extracts, and increased with higher root extract concentrations. The germination of cocks comb ( Celosia argentea ) and rose moss ( Portulaca grandiflora ) seeds were not inhibited by the application of T. undulata extracts. The results showed that the extracts of T. undulata have allelopathic effects on seed germination and seedling growth of the two monocotyledonous plants tested but not with the two dicotyledonous plants tested. T. undulata extracts may have selective potential for natural weed control. [ABSTRACT FROM AUTHOR]

The genus Ostreopsis includes several toxic species that can develop blooms in benthic ecosystems, with potential harmful consequences for human health and marine invertebrates. Despite of this, little is known about the allelopathic interactions between these organisms and other co-occurring microalgae that exploit similar spatial and nutrient resources in benthic ecosystems. The aim of this study was to follow these interactions in cultures of two Ostreopsis ribotypes with different toxin profiles ( O . cf. ovata contained ovatoxins-a, b, c and e, while only ovatoxin-d was found in O . sp. “ Lanzarote-type”), mixed with species of three benthic dinoflagellate genera ( Coolia , Prorocentrum and Gambierdiscus ), isolated from the same area (North East Atlantic, Canary Islands). In a first experiment, the potential allelopathic effects on growth rates were followed, in mixed cultures of Coolia monotis (a non toxic species) exposed to the clarified medium and to cells of O . sp. “ Lanzarote-type” and O . cf. ovata . Growth delayed in C. monotis was observed specially in clarified medium, while the O. sp. “ Lanzarote-type” strain attained much lower densities in mixed cultures. In a second experiment, we examined the potential effects of clarified media from O. sp. “ Lanzarote-type” and O . cf. ovata on the adherence capacity in two toxic species ( Prorocentrum hoffmannianum and Gambierdiscus excentricus ). Contrasting effects were found: a significant increase of adherence capacity in P. hoffmannianum vs attachment decline in G. excentricus , that experienced also severe deleterious effects (cell lysis). Our results suggest the existence of weak to moderate allelopathic interactions between the studied organisms, although the outcome is dependent on the species involved. [ABSTRACT FROM AUTHOR]

In this study, we investigated the allelopathic interactions among five representative allelochemicals at different proportions using bloom-forming Microcystis aeruginosa as the test receptor. Binary or ternary mixtures of allelochemicals obtained three types of allelopathic interactions, i.e., synergistic, antagonistic, and additive effects. However, combinations of four or five allelochemicals only yielded antagonistic effects. Interestingly, the algal inhibition gradually increased with the tested period for all treatments. For instance, the synergistic interaction occurred with the mixture including coumarin + ρ-hydroxybenzoic acid at 80%:20%; the mixture on the 10th day showed 0.80 of algal inhibition. While the mixture comprised protocatechuic acid + stearic acid + ρ-aminobenzene-sulfonic acid at 33.3%:33.3%:33.3%, the additive interactions occurred and then the maximum algal inhibition (0.83) was acquired at the end of tested period. In conclusion, the joint effects of different allelochemicals depend on various factors such as the chemicals used, their respective proportions, the total concentration of the mixture, and the receptor species. Thus, it is necessary to consider the complexity of allelopathic interactions and the field conditions during the control and management of noxious cyanobacteria. [ABSTRACT FROM AUTHOR]

Characteristics of the highly pernicious weed ipomoea (Ipomoea carnea) were studied before and after its vermicomposting by the earthworm (Eisenia fetida). The studies, supported by UV-visible and Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) and differential scanning calorimetry (DSC), gas chromatography-mass spectrometry (GC-MS), and scanning electron microscopy (SEM) reveal a drastic change in the characteristics. There was a sharp reduction in the carbon-to-nitrogen ratio from 26.1 to 9.9, and in humification index from 7.7 to 1.9. By all accounts there was substantial mineralization of organic matter. Complex aromatics such as lignin and polyphenols were degraded into simpler carbohydrates and lipids. GC-MS analysis showed significant fragmentation, bio-oxidation and molecular rearrangements of chemical compounds in vermicompost in comparison to those in ipomoea. SEM micrographs of ipomoea vermicompost reflected strongly disaggregated material compared to ipomoea. The phenols and alkaloids which are specifically responsible for the toxicity and allelopathy of ipomoea, were significantly degraded in the course of the weed's vermicomposting, turning it into a plant-friendly organic fertilizer. These findings make it appear possible that millions of tons of ipomoea biomass, which is generated annually but goes to waste, can be transformed into organic fertilizer. [ABSTRACT FROM AUTHOR]

Seedling root and shoot growth in hydroponics and allelopathic activity using a bioassay have been studied in very diverse populations of winter wheat grown under either organic or conventional conditions for a number of generations and subjected only to natural selection. The study was conducted on seeds from generation 6 (F 6 ) and 11 (F 11 ) from three composite cross populations (CCPs) produced by the Organic Research Centre in the UK. Since the F 5 the populations were maintained under organic and conventional conditions in Germany. Two parallel populations were created from each CC, resulting in a total of six organic and six conventional CCPs. The sets of parallel populations showed similar evolutionary trends indicating that the observed changes are related to differences in management rather than chance. Seedling root length and seedling root and shoot weight in the F 11 of the organically-managed CCPs were significantly greater than in the organic F 6 CCPs. In the conventionally-managed CCPs no such differences were observed. Both organic and conventional CCPs produced for quality showed higher early root and shoot growth than those produced for yield pointing to genetic differences among population types and highlighting the importance of early vigour for NUE. There were no significant differences in the allelopathic activity of the populations and between generations. The Shannon-Weaver diversity indices were similar for the studied traits in organic and conventional CCPs and hence no major changes in diversity had occurred between F 6 to F 11 . As changes in plant height were small and weed pressure in the fields low it is concluded that the observed differences are more related to NUE, rather than intra-specific competition for light or the direct effect of increased weed pressure in the organic system. [ABSTRACT FROM AUTHOR]

A large survey of antimicrobial resistance of Helicobacter pylori was performed in France in 2014: 984 patients were enrolled by 75 gastroenterologists all over the country. Among the 783 patients who had never received eradication treatment before, 266 (33.9%) were H. pylori positive. The strains showed a high rate of clarithromycin resistance (22.2%), moderate rate of resistance to levofloxacin (15.4%) and high rate of resistance to metronidazole (45.9%). In all, 187 patients had received previous treatment, of which 115 were H. pylori positive with very high resistance to clarithromycin (73.9%) and metronidazole (78.3%). None of the patients receiving PYLERA (Bismuth salt-Tetracycline HCl-Metronidazole) proton-pump inhibitor developed resistance to tetracycline. A real-time PCR applied to gastric biopsy specimens detected all the cases that were positive by culture as well as 30 additional cases. A good correlation was found between the clarithromycin resistance detected by phenotypic methods and the associated mutations for clarithromycin resistance, which has continued to increase in the last decade but at a lower rate than previously observed. [ABSTRACT FROM AUTHOR]

Resource conservation technologies (RCTs) offers pragmatic options to cut down fuel, labor and water resources. In Pakistan, the use of RCTs started in the form of a New Zealand imported zero tillage wheat (ZTW) drill in 1983, and now the ZTW plantation has reached to an area of 507,050 ha. However, initially, the widespread adoption of the ZTW plantation was hampered because of insufficient training and dissemination of information on the proper use of the machinery and planting techniques in Pakistan. In the past few years, rapid uptake of RCTs has been noted in rice-wheat cropping system (RWCS) in Punjab region of Pakistan, the main hub of RCTs, due to direct involvement of farmers during experimentation, and strong collaboration with local machinery manufacturers. In 1992, the inverted ‘T’ openers' technology, was introduced in locally manufactured ZT drills, which helped to make zero tillage (ZT), a user-friendly technology, acceptable at farm level. Now ZT drills equipped with inverted ‘T’ coulter technology are available at cheap and affordable rates. Still many farmers do not have access to RCTs machinery, which requires serious attention of policy makers. After the preliminary experiments on direct seeded aerobic rice (DSAR) in RWCS by rice-wheat consortium and Cereal System Initiative for South Asia, the technology has been widely spread on large area in RWCS in Pakistan in recent years. The other RCTs such as laser land levelling and bed planting of crops are also taking roots in various cropping zones of Pakistan, especially in RWCS. Although, RCTs resolves time and edaphic conflicts, reduces the production cost and save plenty of water; nonetheless weed problem has emerged as serious issues in the adoption of RCTs (especially ZTW, DSAR) in Pakistan. In ZT systems, no preparatory tillage is carried out, which favors the growth of many weeds (e.g., perennial weeds). Likewise, absence of flooding conditions in DSAR favors the growth of many weeds. Change in weed flora from annual to perennial weeds has been observed in ZT systems. However, pre-emergence application of pendimethalin, thiobencarb, butachlor, oxyfluorfen oxadiazon, and nitrofen followed by post-emergence herbicides such as ethoxysulfuron, bispyribac sodium, acetochlor and butachlor provides fair weed control in DSAR in Pakistan. Nonetheless repeated use of herbicides with similar mode of action for managing weeds in ZTW and DSAR in Pakistan may induce herbicide resistance in weeds as has been reported in various parts of the world. In this scenario, the integrated weed management strategies may be useful to control weeds in ZTW and DSAR. The strategies for weed management in DSAR may include the use of stale seedbed technique, use of mulches of allelopathic crops like sorghum, crop rotations with allelopathic crops, intercropping with allelopathic crops, use of allelopathic water extracts, and breeding of competitive crop cultivars. Moreover, strong socio-economic mobilization at farmer fields, extensive research, development, extension and training strategies are required for long term sustainability and tackling the problems of weeds in Pakistan for the rapid uptake of RCTs. [ABSTRACT FROM AUTHOR]

Composition and temporal variation of the microphytobenthos communities of the Conero Riviera (northern Adriatic Sea) were investigated in the course of an annual cycle, focusing on their relationships with blooms of the benthic dinoflagellate Ostreopsis cf. ovata . Sampling was carried out from March 2009 to March 2010 on undisturbed benthic substrata (macroalgae and pebbles). Samples for the study of microphytobenthos were collected with a monthly frequency, while those for the study of Ostreopsis bloom weekly. Benthic diatoms dominated the microphytobenthos communities for most of the annual cycle (except the summer), both in terms of abundance and biomass. In summer, cyanobacteria were dominant (54.04 ± 9.18 and 24.29 ± 11.11% of total abundance and biomass, respectively), while benthic dinoflagellates were an important component of the community in terms of biomass only at the peak of the Ostreopsis bloom in late summer (up to 91% of the total biomass). Among diatoms, the most abundant forms throughout the year were motile species (77.5 ± 3.71% of the population), while erect diatoms formed the majority of the biomass in winter and spring (48.66 ± 16.66 and 48.05 ± 5.56% of total population, respectively). Diatoms were mainly affected by DIN availability, while the patterns of biomass of O. cf. ovata and cyanobacteria were related to salinity and temperature. The biomass of Ostreopsis was also affected by the availability of phosphorus. The results of this study suggest that the proliferation of Ostreopsis affected the structure of the benthic diatom community: motile diatoms were significantly more abundant during the Ostreopsis bloom peak than during the rest of summer, probably because they benefited from the abundant mucilaginous mat covering the benthic substrata. In the course of the O . cf. ovata bloom the diversity of the microphytobenthos was significantly lower than during the rest of the year, suggesting an influence of both the shading produced by the mucous mat and allelopathic compounds possibly produced by O. cf. ovata . [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the phytochemical content and allelopathic potential of various organic extracts from seeds and pods of three Tunisian species of Acacia ( Acacia cyclops , Acacia mollissima and Acacia cyanophylla ) which was evaluated on lettuce germination and seedling growth. The total flavonoid contents in the organic extracts were closely ranged (3.1–24 mg RE/100 g DW), n -butanol extracts of Acacia pods were the richest ones in phenol and condensed tannin contents. For allelopathic activity, the EtOAc extract of seeds from A. cyanophylla inhibited the germination of the target seeds. The seedling growth was inhibited by all organic extracts with disproportion. The chromatographic separation methods led to isolation of a triterpenoid saponin named mollisside B from A . cyclops pods n -butanol extract. The allelopathic effect of this compound was evaluated on Lactuca sativa L. At a concentration of 200 μg/mL, the isolate has influenced on seedling growth with percentages of inhibition of 63.68% and 88.21% for shoot and root length, respectively. [ABSTRACT FROM AUTHOR]

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

The application of nanoparticulate molecularly imprinted polymers (NMIPs) as molecular recognition element in piezoelectric chemical sensors for the detection of penicillins is reported. Using NMIPs obtained via precipitation polymerization, a synthetic receptor layer was formed at the surface of a piezoelectric sensor in direct format and nanoparticles were used also as synthetic antibodies in a competitive pseudoimmunoanalysis format. Thus obtained calibration functions provide a linear range at a concentration of 0.1–0.5 μg mL −1 for penicillin G, and 0.1–1.0 μg mL −1 for ampicillin with limits of detection at 0.04 and 0.09 μg mL −1 , respectively. These analytical figures of merit are below the mandated maximum residue limits (MRL) for such antibiotics in meat, therefore rendering the developed device suitable for applications in food industries. The sensors were tested at the analysis of real objects. [ABSTRACT FROM AUTHOR]

The increase in anthropogenic nutrient loading affecting many freshwater ecosystems combined with global warming may lead to cyanobacterial blooms on an increasingly frequent basis. Among the various physicochemical and biological methods which have been proposed to rapidly control blue-green algae growth, the use of plant-derived substances such as allelochemicals has gained great interest as an environment-friendly approach. The primary aim of this work was to evaluate the efficiency of gallic and nonanoic acid application to preemptively inhibit cyanobacterial growth in lentic hydrosystems. In order to address the process feasibility under realistic exposure scenarios, thirteen outdoor freshwater mesocosms (unit volume: 3 m 3 ) were designed, each containing phytoplankton (including local blue-green algae species) and various non-target organisms from higher trophic levels ( Physa , Lymnaea , Gammarus , and Scardinius erythrophthalmus ). After an 8-week mesocosm stabilization period, a full factorial design based on the presence/absence of gallic acid (GA) and nonanoic acid (NA) (including a control group) was implemented into the exposure tanks. Regular monitoring of major phytoplankton taxa was conducted during a 28-day experiment using an on-line fluorometer. The main results suggested that gallic acid was more efficient than nonanoic acid at limiting cyanobacterial growth at concentrations as low as 1 mg L − 1 . Successive gallic acid applications (at 1, 2 and 4 mg L − 1 ) at the early stages of cyanobacterial growth did not allow the complete elimination of blue-green algae from the mesocosms. However, the specificity of the allelopathic effect of gallic acid towards cyanobacteria was compatible with the maintenance of a primary productivity in the treated tanks as indicated by the photoautotrophic growth of other algal taxa. Finally, no biomarker induction signal could be reported in non-target species. Further gallic acid application trials in lentic systems such as small freshwater ponds may help to design innovative allelopathy-based aquatic ecotechnologies. [ABSTRACT FROM AUTHOR]

Ichthyotoxic algal blooms cause economic losses throughout the world. However, the mechanisms and molecules proposed so far fail to explain the massiveness of these events. In this research, the allelopathic effect of two bloom-forming species (the raphidophyte Heterosigma akashiwo and dinoflagellate Alexandrium catenella) was evaluated between them and with Rhodomonas salina bioassay. Mono- and co-cultures were carried out with the aim of providing evidence of the relation between allelopathy and ichthyotoxicity. The allelopathic inhibitory effect of the A. catenella's supernatant was significantly enhanced when supernatants were obtained from co-cultures with direct contact between these species. We could not observe any allelopathic response provoked by H. akashiwo. On the other hand, A. catenella was able to decrease the cell concentration of H. akashiwo and R. salina. Besides, allelopathy and ichthyotoxicity were found for A. catenella's supernant, being the allelopathic effect not related to saxitoxin. These results reinforce the hypothesis that the allelopathic effect being regulated by the presence of other microalgae and could be responsible for ichthyotoxicity. • Allelopathic compounds exuded appear to correlate with ichthyotoxicity in Alexandrium catenella. • Competition (co-cultivation) generates an increase in the production of allelochemicals. • Saxitoxin did not inhibit competing microalga nor produce in vitro ichthyotoxicity. [ABSTRACT FROM AUTHOR]

The occurrence of antibiotics in subsurface environments is increasingly reported recently in addition to the widespread distribution in surface waters. However, the mechanisms governing the transport of antibiotics from surface into subsurface are not well understood. In this study, the transport of tetracycline in saturated sand columns were investigated in the presence and absence of humic acid (HA) at different ionic strengths and cationic types. NaCl (0–0.1 M) and CaCl 2 (0–0.1 M) were used as representatives of mono- and divalent cations in subsurface. The presence of HA moderately facilitated the transport of tetracycline in sand columns. The presence of Na + inhibited the transport of tetracycline and HA through increasing the deposition of HA aggregates on the sands. The inhibition increased slightly with the increase in Na + concentration from 0 to 0.1 M. In contrast, the presence of Ca 2+ dramatically inhibited the transport of tetracycline and HA even at a low concentration of 0.001 M, which was attributed to the increased aggregation of HA and the greater electrostatic attractive interactions. Results from this study improve our understanding on the penetration of antibiotics from surface into subsurface waters and the transport of antibiotics in saturated aquifers at environmentally relevant conditions. [ABSTRACT FROM AUTHOR]

Marine sessile organisms often inhabit rocky substrata, which are crowded by other sessile organisms. They acquire living space via growth interactions and/or by allelopathy. They are known to secrete toxic compounds having multiple roles. These compounds have been explored for their possible applications in cancer chemotherapy, because of their ability to kill rapidly dividing cells of competitor organisms. As compared to the therapeutic applications of these compounds, their possible ecological role in competition for space has received little attention. To select the potential candidate organisms for the isolation of lead cytotoxic molecules, it is important to understand their chemical ecology with special emphasis on their allelopathic interactions with their competitors. Knowledge of the ecological role of allelopathic compounds will contribute significantly to an understanding of their natural variability and help us to plan effective and sustainable wild harvests to obtain novel cytotoxic chemicals. This review highlights the significance of studying allelopathic interactions of marine invertebrates in the discovery of cytotoxic compounds, by selecting sponge as a model organism. [ABSTRACT FROM AUTHOR]

The allelopathic effect of the raphidophyte Chattonella marina var. marina on the dinoflagellate Gymnodinium catenatum was determined. Both species are harmful algal bloom forming algae, produce toxic metabolites, and can co-exist in the environment. In general, raphidophytes tend to dominate over dinoflagellates, which may indicate an allelopathic effect of the former algae. Strains of C. marina var. marina and G. catenatum isolated from Bahía de La Paz were cultured in bi-algal cultures with and without cell contact. Additionally, cultures of G. catenatum were exposed to cell-free culture filtrates of the raphidophyte to test whether soluble allelopathic molecules are active. During late stationary phase, both species were cultivated in mixed cultures for 72 h using the following cell abundance proportions: 20 × 10 3 cells L −1 : 20 × 10 3 cells L −1 (1:1; G. catenatum : C . marina ); 10 × 10 3 cells L −1 : 20 × 10 3 cells L −1 (1:2), and 20 × 10 3 cells L −1 : 10 × 10 3 cells L −1 (2:1). Cells of G. catenatum were also exposed to different volumes of cell filtrates of C. marina (10, 20, and 50 mL) using the same cell abundance proportions for 24 h. Samples were taken daily for cell counts and microscopic observations. Growth inhibition was higher when there was cell contact between both species, however mortality of G. catenatum was also observed without direct cell contact, indicating that toxic metabolites are liberated to the culture medium. Changes in cell morphology of G. catenatum occurred in the presence of cells and filtrates of C. marina , such as loss of flagella and motility, swelling, loss of girdle and sulci, prominent nucleus, rupture of cell membrane, and cell lysis. Induction of temporary cysts was also observed. These results suggest that toxic metabolites are liberated to the medium by C. marina , affecting G. catenatum by inhibiting its growth and causing changes in its life history, providing new insights of interactions between raphidophytes and dinoflagellates that could happen in the natural environment when both species are present. [ABSTRACT FROM AUTHOR]

Açaí ( Euterpe oleracea ) is a very popular fruit in the Brazilian Amazon consumed as a nourishing and tasty food. Studies suggest that E. oleracea has therapeutic effects on problems like cancer, hypocholesterolemia, fatty liver, malaria, and neurodegeneration. The supercritical fluid extractions were performed with supercritical CO 2 at densities of 700, 800, and 900 kg/m 3 while varying three and eight nominal values of temperature and pressure, respectively. The extracts were analyzed for total fatty acid contents and allelopathic effects. In addition, lyophilized açaí berry pulp was analyzed before and after supercritical CO 2 extraction to determine phenolic compounds and anthocyanin contents. The açaí extract isotherm of 70 °C showed the highest yields at the pressures applied while the isotherm of 60 °C showed the lowest yields. Thus, the fatty acids profile analysis of açaí extract indicates a low saturated/unsaturated ratio and the amount of MUFA is greater than of PUFA. The extracts had phytotoxic effect for the species Mimosa pudica and some extracts had stimulatory effects on Senna obtusifolia germination. Radicle and hypocotyl growths were shorter for the species M. pudica than for S. obtusifolia . The phenolic compounds and anthocyanin contents in the lyophilized açaí berry pulp after CO 2 -SE shows potential applications for nutraceutical purposes. [ABSTRACT FROM AUTHOR]

The present study describes chemical composition, antioxidant, antibacterial, allelopathic and insecticidal properties of essential oil of Thymus algeriensis (Lamiaceae), a North African endemic species. The essential oil from all organs of T. algeriensis were extracted by hydrodistillation and analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS). A high variation among organs for the majority of compounds was shown. Caryophyllene oxide (21.1%) and veridiflorol (17.2%) were the main constituents in roots, while elemol (10.2%) and caryophyllene oxide (17.8%) were identified as the main constituents for stems. Leaves were characterized by high levels of α - pinene (19.5%), 1,8-cineole (11.6%) and camphor (10.4%). Based on the determination of the diameter of inhibition and the determination of the minimum inhibitory concentration, a moderate to high antibacterial activity according to oils was revealed against five bacteria strains. However, oils from Dj. Jdidi locality showed higher bactericidal effect (MICs = 1–3.25 μl/ml) than those from other samples. The level of antioxidant activity estimated by DPPH (IC 50 = 4.31–9.23 mg/ml) and ABTS (11.69–28.23 μgTE/mg DW) test was moderate. The obtained results also showed that the leaf oils inhibited the shoot and root growth of Medicago sativa and Triticum æstivum seedlings. Thus, the T. algeriensis oils may be used as a natural herbicide. Furthermore, these oils were found to possess strong insecticidal activity (LC 50 = 44.25–112.75 μl/l air) against cotton leafworm larvae. Thus, the essential oil of this plant could be used as a potential source of natural antioxidants and bioactive molecules in pharmaceutical as well as in food industries. [ABSTRACT FROM AUTHOR]