The role of microbial partners in heavy metal metabolism in plants: a review.

Heavy metal pollution threatens plant growth and development as well as ecological stability. Here, we synthesize current research on the interplay between plants and their microbial symbionts under heavy metal stress, highlighting the mechanisms employed by microbes to enhance plant tolerance and resilience. Several key strategies such as bioavailability alteration, chelation, detoxification, induced systemic tolerance, horizontal gene transfer, and methylation and demethylation, are examined, alongside the genetic and molecular basis governing these plant-microbe interactions. However, the complexity of plant-microbe interactions, coupled with our limited understanding of the associated mechanisms, presents challenges in their practical application. Thus, this review underscores the necessity of a more detailed understanding of how plants and microbes interact and the importance of using a combined approach from different scientific fields to maximize the benefits of these microbial processes. By advancing our knowledge of plant-microbe synergies in the metabolism of heavy metals, we can develop more effective bioremediation strategies to combat the contamination of soil by heavy metals.

The promoting effects of soil microplastics on alien plant invasion depend on microplastic shape and concentration.

Both alien plant invasions and soil microplastic pollution have become a concerning threat for terrestrial ecosystems, with consequences on the human well-being. However, our current knowledge of microplastic effects on the successful invasion of plants remains limited, despite numerous studies demonstrating the direct and indirect impacts of microplastics on plant performance. To address this knowledge gap, we conducted a greenhouse experiment involving the mixtures of soil and low-density polyethylene (LDPE) microplastic pellets and fragments at the concentrations of 0, 0.5 % and 2.0 %. Additionally, we included Solidago decurrens (native plant) and S. canadensis (alien invasive plant) as the target plants. Each pot contained an individual of either species, after six-month cultivation, plant biomass and antioxidant enzymes, as well as soil properties including soil moisture, pH, available nutrient, and microbial biomass were measured. Our results indicated that microplastic effects on soil properties and plant growth indices depended on the Solidago species, microplastic shapes and concentrations. For example, microplastics exerted positive effects on soil moisture of the soil with native species but negative effects with invasive species, which were impacted by microplastic shapes and concentrations, respectively. Microplastics significantly impacted catalase (P < 0.05) and superoxide dismutase (P < 0.01), aboveground biomass (P < 0.01), and belowground/aboveground biomass (P < 0.01) of the native species depending on microplastic shapes, but no significant effects on those of the invasive species. Furthermore, microplastics effects on soil properties, nutrient, nutrient ratio, and plant antioxidant enzyme activities contributed to plant biomass differently among these two species. These results suggested that the microplastics exerted a more pronounced impact on native Solidago plants than the invasive ones. This implies that the alien invasive species displays greater resistance to microplastic pollution, potentially promoting their invasion. Overall, our study contributes to a better understanding of the promoting effects of microplastic pollution on plant invasion.

Unraveling the ecological threads: How invasive alien plants influence soil carbon dynamics.

Invasive alien plants (IAPs) pose significant threats to native ecosystems and biodiversity worldwide. However, the understanding of their precise impact on soil carbon (C) dynamics in invaded ecosystems remains a crucial area of research. This review comprehensively explores the mechanisms through which IAPs influence soil C pools, fluxes, and C budgets, shedding light on their effects and broader consequences. Key mechanisms identified include changes in litter inputs, rates of organic matter decomposition, alterations in soil microbial communities, and shifts in nutrient cycling, all driving the impact of IAPs on soil C dynamics. These mechanisms affect soil C storage, turnover rates, and ecosystem functioning. Moreover, IAPs tend to increase gross primary productivity and net primary productivity leading to the alterations in fluxes and C budgets. The implications of IAP-induced alterations in soil C dynamics are significant and extend to plant-soil interactions, ecosystem structure, and biodiversity. Additionally, they have profound consequences for C sequestration, potentially impacting climate change mitigation. Restoring native plant communities, promoting soil health, and implementing species-specific management are essential measures to significantly mitigate the impacts of IAPs on soil C dynamics. Overall, understanding and mitigating the effects of IAPs on soil C storage, nutrient cycling, and related processes will contribute to the conservation of native biodiversity and complement global C neutrality efforts.

Correction: Biogenic synthesis of silver nanoparticles using Rubus fruticosus extract and their antibacterial efficacy against Erwinia caratovora and Ralstonia solanacearum phytopathogens.

[This corrects the article DOI: 10.1039/D3RA06723H.].

Biogenic synthesis of silver nanoparticles using Rubus fruticosus extract and their antibacterial efficacy against Erwinia caratovora and Ralstonia solanacearum phytopathogens.

In the current research, we produced green, cost-effective, eco-friendly silver nanoparticles using a single-step approach. Plants are considered highly desirable systems for nanoparticle synthesis because they possess a variety of secondary metabolites with significant reduction potential. In the current research, the dried leaf extract of Rubus fruticosus was utilized as a capping and reducing agent for the fabrication of silver nanoparticles, to prepare reliable biogenic silver nanoparticles and subsequently to investigate their potential against some common phytopathogens. The prepared silver nanoparticles were exploited to quantify the total flavonoid content (TFC), total phenolic content (TPC) and DPPH-based antioxidant activity. Different concentrations of aqueous extracts of plant leaves and silver nitrate (AgNO3) were reacted, and the color change of the reactant mixture confirmed the formation of Rubus fruticosus leaf-mediated silver nanoparticles (RFL-AgNPs). A series of characterization techniques such as UV-vis spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis and X-ray diffraction revealed the successful synthesis of silver nanoparticles. The surface plasmon resonance peak appeared at 449 nm. XRD analysis demonstrated the crystalline nature, EDX confirmed the purity, and TEM demonstrated that the nanoparticles are mostly spherical in form. Furthermore, the biosynthesized nanoparticles were screened for in vitro antibacterial activity, antioxidant activity, and total phenolic and flavonoid content. The nanoparticles were used in different concentrations alone and in combination with plant extracts to inhibit Erwinia caratovora and Ralstonia solanacearum. In high-throughput assays used to inhibit these plant pathogens, the nanoparticles were highly toxic against bacterial pathogens. This study can be exploited for planta assays against phytopathogens utilizing the same formulations for nanoparticle synthesis and to develop potent antibacterial agents to combat plant diseases.

Microplastic contamination in the agricultural soil-mitigation strategies, heavy metals contamination, and impact on human health: a review.

Microplastic pollution has emerged as a critical global environmental issue due to its widespread distribution, persistence, and potential adverse effects on ecosystems and human health. Although research on microplastic pollution in aquatic environments has gained significant attention. However, a limited literature has summarized the impacts of microplastic pollution the agricultural land and human health. Therefore, In the current review, we have discussed how microplastic(s) affect the microorganisms by ingesting the microplastic present in the soil, alternatively affecting the belowground biotic and abiotic components, which further elucidates the negative effects on the above-ground properties of the crops. In addition, the consumption of these crops in the food chain revealed a potential risk to human health throughout the food chain. Moreover, microplastic pollution has the potential to induce a negative impact on agricultural production and food security by altering the physiochemical properties of the soil, microbial population, nutrient cycling, and plant growth and development. Therefore, we discussed in detail the potential hazards caused by microplastic contamination in the soil and through the consumption of food and water by humans in daily intake. Furthermore, further study is urgently required to comprehend how microplastic pollution negatively affects terrestrial ecosystems, particularly agroecosystems which drastically reduces the productivity of the crops. Our review highlights the urgent need for greater awareness, policy interventions, and technological solutions to address the emerging threat of microplastic pollution in soil and plant systems and mitigation strategies to overcome its potential impacts on human health. Based on existing studies, we have pointed out the research gaps and proposed different directions for future research.

Biochar and saline soil: mitigation strategy by incapacitating the ecological threats to agricultural land.

Soil salinity caused a widespread detrimental issue that hinders productivity in agriculture and ecological sustainability, while waste-derived soil amendments like biochar have drawn attention for their capacity to act as a mitigating agent, by enhancing the physical and chemical features of soil, and contributing to the recovery of agricultural waste resources. However, the information concerning biochar and salinity which affect the physicochemical characteristics of soils, crop physiology, and growth is limited. To investigate whether biochar mitigates the salinity stress on wheat crop seedlings, we grow them with salinity stress (120 mM), and biochar (20 tons ha-1), and its interactive effects. The soil properties of soil organic carbon (SOC), soil organic matter (SOM), dissolved organic carbon (DOC), and soil available phosphorus (SAP) decreased in the saline soil by 36.71%, 46.97%, 26.31%, and 15.00%, while biochar treatment increased SOC, DOC, and SAP contents by 7.42%, 31.57%, and 15.00%, respectively. On the other hand, dissolved organic nitrogen (DON) contents decreased in all the treatments compared to the control. The root growth traits, SPAD values, leaf nitrogen, photosynthetic parameters, antioxidant enzymes, and reactive oxygen species decreased in the saline treatment while increasing in the biochar and interactive treatment. Thus, these activities resulted in higher leaves and root biomass in the biochar treatment alone and interactive treatment of salinity and biochar. According to principal component analysis, redundancy analysis, and the mantel test, using biochar in conjunction with salinity treatment was found to be more effective than salinity treatment alone. The results of this study suggest that biochar can be used as a sustainable agricultural technique and a means of mitigation agent by lowering soil salinity while increasing the biomass of crops.

Biochar improves the physical and nutritional quality of soil and plant function.Salinity stress declined the physiological activities and biomass of the crop.Biochar mitigates the salinity stress in soil and enhances the plant functioning.Exposure to both treatments enhances the antioxidant enzyme activity and biomass.

The detrimental effects of heavy metals on tributaries exert pressure on water quality, Crossocheilus aplocheilus, and the well-being of human health.

The escalating presence of heavy metals (HMs) in the Panjkora River water and their impact on fish pose a significant challenge to both the ecological community and human health. Consequently, a study was conducted with the primary aim of elucidating their influence on human health-related issues. To address this, the concentrations of heavy metals, including arsenic (As), cadmium (Cd), iron (Fe), manganese (Mn), lead (Pb), and zinc (Zn), in both water and the fish species Crossocheilus diplocheilus were investigated across various locations within the study area. The quantification of HMs concentration was carried out utilizing an atomic absorption spectrophotometer. The highest concentration in water was found as 0.060 mg/L for Pb and lowest for Fe, whereas the highest concentration in fish was 2.028 mg/kg for Pb and lowest for As. Human health risk associated with fish eating was evaluated by using health risk indices (HRI) for non-carcinogenic health risks and targeted cancer risk (TR) for carcinogenic health risks. The values of the health risk index (HRI) were found greater than 1 except Fe (0.0792), Zn (0.782), and Mn (0.541). The highest mean HRI > 1 was recorded for As (62.99), Cd (26.85), and Pb (10.56). This implies that fish consumption from river Panjkora is not safe up to some extent. Similarly, the TR value for As, Cd, and Pb was found 2.8 [Formula: see text], 1.6 [Formula: see text], 2.8 ×[Formula: see text] which showed cancer risk. There is a detected risk to human health associated with the consumption of fish from the Panjkora River. The government must implement adaptive measures to address this significant issue of water pollution in the study area. Additionally, there is a need for further extensive and prolonged research studies in this context.

Glucose input profit soil organic carbon mineralization and nitrogen dynamics in relation to nitrogen amended soils.

Exogenous carbon (C) inputs stimulate soil organic carbon (SOC) decomposition, strongly influencing atmospheric concentrations and climate dynamics. The direction and magnitude of C decomposition depend on the C and nitrogen (N) addition, types and pattern. Despite the importance of decomposition, it remains unclear whether organic C input affects the SOC decomposition under different N-types (Ammonium Nitrate; AN, Urea; U and Ammonium Sulfate; AS). Therefore, we conducted an incubation experiment to assess glucose impact on N-treated soils at various levels (High N; HN: 50 mg/m2, Low N; LN: 05 mg/m2). The glucose input increased SOC mineralization by 38% and 35% under HN and LN, respectively. Moreover, it suppressed the concentration of NO3--N by 35% and NH4+-N by 15% in response to HN and LN soils, respectively. Results indicated higher respiration in Urea-treated soils and elevated net total nitrogen content (TN) in AS-treated soils. AN-amended soil exhibited no notable rise in C mineralization and TN content compared to other N-type soils. Microbial biomass carbon (MBC) was higher in glucose treated soils under LN conditions than control. This could result that high N suppressed microbial N mining and enhancing SOM stability by directing microbes towards accessible C sources. Our results suggest that glucose accelerated SOC mineralization in urea-added soils and TN contents in AS-amended soils, while HN levels suppressed C release and increased TN contents in all soil types except glucose-treated soils. Thus, different N-types and levels play a key role in modulating the stability of SOC over C input.

Micro/nanoplastics: Critical review of their impacts on plants, interactions with other contaminants (antibiotics, heavy metals, and polycyclic aromatic hydrocarbons), and management strategies.

Microplastic/nanoplastics (MPs/NPs) contamination is not only emerging threat to the agricultural system but also constitute global hazard to the environment worldwide. Recent review articles have addressed the environmental distribution of MPs/NPs and their single-exposure phytotoxicity in various plant species. However, the mechanisms of MPs/NPs-induced phytotoxicity in conjunction with that of other contaminants remain unknown, and there is a need for strategies to ameliorate such phytotoxicity. To address this, we comprehensively review the sources of MPs/NPs, their uptake by and effects on various plant species, and their phytotoxicity in conjunction with antibiotics, heavy metals, polycyclic aromatic hydrocarbons (PAHs), and other toxicants. We examine mechanisms to ameliorate MP/NP-induced phytotoxicity, including the use of phytohormones, biochar, and other plant-growth regulators. We discuss the effects of MPs/NPs -induced phytotoxicity in terms of its ability to inhibit plant growth and photosynthesis, disrupt nutrient metabolism, inhibit seed germination, promote oxidative stress, alter the antioxidant defense system, and induce genotoxicity. This review summarizes the novel strategies for mitigating MPs/NPs phytotoxicity, presents recent advances, and highlights research gaps, providing a foundation for future studies aimed at overcoming the emerging problem of MPs/NPs phytotoxicity in edible crops.

Soil nutrient levels regulate the effect of soil microplastic contamination on microbial element metabolism and carbon use efficiency.

Microplastics (MPs) are emerging environmental contaminants in soil ecosystems that disrupt the soil carbon (C) pool. Therefore, the response of microbial metabolism to MP-contaminated soil is crucial for soil-C stabilization. We undertook factorial experiments in a greenhouse with three types of soil microplastics with three levels of soil nutrients and undertook soil physiochemical analyses after 60 days. The present study revealed how the presence of degradable polylactic acid (PLA) and non-degradable polyethylene (PE) MPs affects soil microbial nutrient limitation and C use efficiency (CUE) at varying nutrient concentrations. The presence of PLA in soil with low nutrient levels led to a significant increase (29%) in the activities of nitrogen (N)-acquiring enzymes. In contrast, the presence of MPs had no effect on C- and N-acquiring enzymes. The occurrence of PE caused a 41% reduction in microbial C limitation in high-nutrient soils, and microbial nutrient metabolism was limited by the occurrence of MPs in soils amended with nutrients. A strong positive correlation between microbial C and nutrient limitation in the soil indicates that addressing C limitation followed by amendment of soil with MPs could potentially intensify microbial N limitation in soils with varying nutrients. In comparison, the microbial CUE increased by 10% with the application of degradable MPs (PLA) to soils with a low nutrient status. These findings highlight the significant influence of both degradable PLA and non-degradable PE MPs on soil microbial processes and C dynamics. In conclusion, PLA enhances metabolic efficiency in nutrient-rich soils, potentially aiding C utilization, whereas PE reduces microbial C limitation, offering promise for soil C sequestration strategies. Our findings underscore the importance of considering MPs in soil ecosystem studies and in broader sustainability efforts.

The toxicological effect on pak choi of co-exposure to degradable and non-degradable microplastics with oxytetracycline in the soil.

Microplastics and antibiotics are emerging as ubiquitous contaminants in farmland soil, harming crop quality and yield, and thus threatening global food security and human health. However, few studies have examined the individual and joint effects of degradable and/or non-degradable microplastics and antibiotics on crop plants. This study examined the individual and joint effects of polyethylene (PE) and polylactic acid (PLA) microplastics and the antibiotic oxytetracycline (OTC) on pak choi by measuring its growth, photosynthesis, antioxidant enzyme activity, and metabolite levels. Microplastics and/or oxytetracycline adversely affected root weight, photosynthesis, and antioxidant enzyme (superoxide dismutase, catalase, and ascorbate peroxidase) activities. The levels of leaf metabolites were significantly altered, causing physiological changes. Biosynthesis of plant secondary metabolites and amino acids was altered, and plant hormones pathways were disrupted. Separately and together, OTC, PE, and PLA exerted phytotoxic and antagonistic effects on pak choi. Separately and together with OTC, degradable microplastics altered the soil properties, thus causing more severe impacts on plant performance than non-degradable microplastics. This study elucidates the effects on crop plants of toxicity caused by co-exposure to degradable or non-degradable microplastic and antibiotics contamination and suggests mechanisms.

Utilizing hydrothermal time models to assess the effects of temperature and osmotic stress on maize (Zea mays L.) germination and physiological responses.

The application of germination models in economic crop management makes them extremely useful for predicting seed germination. Hence, we examined the effect of varying water potentials (Ψs; 0. - 0.3, - 0.6, - 0.9, - 1.2 MPa) and temperatures (Ts; 20, 25, 30, 35, 40 °C) on maize germination and enzymatic antioxidant mechanism. We observed that varying Ts and Ψs significantly influenced germination percentage (GP) and germination rate (GR), and other germination parameters, including germination rate index (GRI), germination index (GI), mean germination index (MGI), mean germination time (MGT), coefficient of the velocity of germination (CVG), and germination energy (GE) (p ≤ 0.01). Maximum (87.60) and minimum (55.20) hydro-time constant (θH) were reported at 35 °C and 20 °C, respectively. In addition, base water potential at 50 percentiles was highest at 30 °C (15.84 MPa) and lowest at 20 °C (15.46 MPa). Furthermore, the optimal, low, and ceiling T (To, Tb and Tc, respectively) were determined as 30 °C, 20 °C and 40 °C, respectively. The highest θT1 and θT2 were reported at 40 °C (0 MPa) and 20 °C (- 0.9 MPa), respectively. HTT has a higher value (R2 = 0.43 at 40 °C) at sub-optimal than supra-optimal temperatures (R2 = 0.41 at 40 °C). Antioxidant enzymes, including peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione peroxidase (GPX), increased with decreasing Ψs. In contrast, CAT and POD were higher at 20 °C and 40 °C but declined at 25, 30, and 35 °C. The APX and GPX remained unchanged at 20, 25, 30, and 40 °C but declined at 35 °C. Thus, maintaining enzymatic activity is a protective mechanism against oxidative stress. A decline in germination characteristics may result from energy diverting to anti-stress tools (antioxidant enzymes) necessary for eliminating reactive oxygen species (ROS) to reduce salinity-induced oxidative damage. The parameters examined in this study are easily applicable to simulation models of Z. mays L. germination under extreme environmental conditions characterized by water deficits and temperature fluctuations.

Physiology of gamma-aminobutyric acid treated Capsicum annuum L. (Sweet pepper) under induced drought stress.

There is now widespread agreement that global warming is the source of climate variability and is a global danger that poses a significant challenge for the 21st century. Climate crisis has exacerbated water deficit stress and restricts plant's growth and output by limiting nutrient absorption and raising osmotic strains. Worldwide, Sweet pepper is among the most important vegetable crops due to its medicinal and nutritional benefits. Drought stress poses negative impacts on sweet pepper (Capsicum annuum L.) growth and production. Although, γ aminobutyric acid (GABA) being an endogenous signaling molecule and metabolite has high physio-molecular activity in plant's cells and could induce tolerance to water stress regimes, but little is known about its influence on sweet pepper development when applied exogenously. The current study sought to comprehend the effects of foliar GABA application on vegetative development, as well as physiological and biochemical constituents of Capsicum annuum L. A Field experiment was carried out during the 2021 pepper growing season and GABA (0, 2, and 4mM) concentrated solutions were sprayed on two Capsicum annuum L. genotypes including Scope F1 and Mercury, under drought stress of 50% and 30% field capacity. Results of the study showed that exogenous GABA supplementation significantly improved vegetative growth attributes such as, shoot and root length, fresh and dry weight, as well as root shoot ratio (RSR), and relative water content (RWC) while decreasing electrolyte leakage (EL). Furthermore, a positive and significant effect on chlorophyll a, b, a/b ratio and total chlorophyll content (TCC), carotenoids content (CC), soluble protein content (SPC), soluble sugars content (SSC), total proline content (TPC), catalase (CAT), and ascorbate peroxidase (APX) activity was observed. The application of GABA at 2mM yielded the highest values for these variables. In both genotypes, peroxidase (POD) and superoxide dismutase (SOD) content increased with growing activity of those antioxidant enzymes in treated plants compared to non-treated plants. In comparison with the rest of GABA treatments, 2mM GABA solution had the highest improvement in morphological traits, and biochemical composition. In conclusion, GABA application can improve development and productivity of Capsicum annuum L. under drought stress regimes. In addition, foliar applied GABA ameliorated the levels of osmolytes and the activities of antioxidant enzymes involved in defense mechanism.

Virosome: An engineered virus for vaccine delivery.

The purpose of immunization is the effective cellular and humoral immune response against antigens. Several studies on novel vaccine delivery approaches such as micro-particles, liposomes & nanoparticles, etc. against infectious diseases have been investigated so far. In contrast to the conventional approaches in vaccine development, a virosomes-based vaccine represents the next generation in the field of immunization because of its balance between efficacy and tolerability by virtue of its mechanism of immune instigation. The versatility of virosomes as a vaccine adjuvant, and delivery vehicle of molecules of different nature, such as peptides, nucleic acids, and proteins, as well as provide an insight into the prospect of drug targeting using virosomes. This article focuses on the basics of virosomes, structure, composition formulation and development, advantages, interplay with the immune system, current clinical status, different patents highlighting the applications of virosomes and their status, recent advances, and research associated with virosomes, the efficacy, safety, and tolerability of virosomes based vaccines and the future prospective.

Unraveling the functional characterization of a jasmonate-induced flavonoid biosynthetic CYP45082G24 gene in Carthamus tinctorius.

The cytochrome P450 superfamily of monooxygenases plays a major role in the evolution and diversification of plant natural products. The function of cytochrome P450s in physiological adaptability, secondary metabolism, and xenobiotic detoxification has been studied extensively in numerous plant species. However, their underlying regulatory mechanism in safflower still remained unclear. In this study, we aimed to elucidate the functional role of a putative CtCYP82G24-encoding gene in safflower, which suggests crucial insights into the regulation of methyl jasmonate-induced flavonoid accumulation in transgenic plants. The results showed that methyl jasmonate (MeJA) was associated with a progressive upregulation of CtCYP82G24 expression in safflower among other treatment conditions including light, dark, and polyethylene glycol (PEG). In addition, transgenic plants overexpressing CtCYP82G24 demonstrated increased expression level of other key flavonoid biosynthetic genes, such as AtDFR, AtANS, and AtFLS, and higher content of flavonoid and anthocyanin accumulation when compared with wild-type and mutant plants. Under exogenous MeJA treatment, the CtCYP82G24 transgenic overexpressed lines showed a significant spike in flavonoid and anthocyanin content compared with wild-type and mutant plants. Moreover, the virus-induced gene silencing (VIGS) assay of CtCYP82G24 in safflower leaves exhibited decreased flavonoid and anthocyanin accumulation and reduced expression of key flavonoid biosynthetic genes, suggesting a possible coordination between transcriptional regulation of CtCYP82G24 and flavonoid accumulation. Together, our findings confirmed the likely role of CtCYP82G24 during MeJA-induced flavonoid accumulation in safflower.

Soil pollution and the invasion of congener Sphagneticola in crop lands.

The input of agro-pollutants, such as microplastics and nanopesticides, on farmlands is widespread and may facilitate biological invasions in agroecosystems. Here, the effects of agro-pollutants that promote invasion of congener species is studied by examining the growth performance of native Sphagneticola calendulacea and its invasive congener, S. trilobata, when grown in a native only, invasive only and mixed community. Sphagneticola calendulacea naturally occurs in croplands in southern China, while S. trilobata was introduced to this region and has since naturalized, encroaching onto farmland. In our study, each plant community was subjected to the following treatments: control, microplastics only, nanopesticides only, and both microplastics and nanopesticides. The effects of the treatments on soils of each plant community were also examined. We found that aboveground, belowground, and photosynthetic traits of S. calendulacea were significantly inhibited by the combined microplastics and nanopesticides treatment in the native and mixed communities. The relative advantage index of S. trilobata was 69.90% and 74.73% higher under the microplastics only and nanopesticides only treatments respectively compared to S. calendulacea. Soil microbial biomass, enzyme activity, gas emission rates, and chemicals in each community were reduced when treated with both microplastics and nanopesticides. Yet, soil microbial biomass of carbon and nitrogen, CO2 emission rates and nitrous oxide rates were significantly higher (56.08%, 58.33%, 36.84% and 49.95% respectively) in the invasive species community than in the native species community under microplastics and nanopesticides. Our results suggest that the addition of agro-pollutants to soils favors the more resistant S. trilobata and suppresses the less tolerant S. calendulacea. Soil properties from the native species community are also more impacted by agro-pollutants than substrates supporting the invasive species. Future studies should explore the effects of agro-pollutants by comparing other invasive and native species and considering human activities, industry, and the soil environment.

Impact of polystyrene microplastics with combined contamination of norfloxacin and sulfadiazine on Chrysanthemum coronarium L.

Antibiotics and microplastics including nanoplastics are emerging contaminants which have become global environmental issues. The application of antibiotics along with microplastics in soil and their entrance in food chain may pose a major threat to human health. The single and combined exposure of polystyrene microplastic (MPS), norfloxacin (NF) and sulfadiazine (SFD) on Chrysanthemum coronarium L. a medicinal food crop, were investigated. Accumulation of nutrient element contents (Fe, Mn, Mg, Zn, K) differentially responded to the single or combined treatments compared to the control. Scanning electron microscopy and transmission electron microscopy analysis indicated that MPS, NF and SFD accumulated in roots, shoots, and leaves and affected their ultrastructure. Compared with that of the single contamination, the co-contamination of microplastics and antibiotics had a greater effect on leaf metabolites due to combination of multiple abiotic stresses. MPS, NF and SFD accumulated from roots and transported to shoots and leaves which ultimately impacts plant metabolites and, nutritional value. They subsequently impact agricultural sustainability and food safety of medicinal food plants. This investigation suggests the possible ecological risks of microplastics to medicinal food plants, especially in co-exposure with organic pollutants like antibiotics and help to reveal potential mechanisms of phytotoxicity of different antibiotics with polyethylene microplastic.

Canada Goldenrod Invasion Regulates the Effects of Soil Moisture on Soil Respiration.

Canada goldenrod (Solidago canadensis L.) is considered one of the most deleterious and invasive species worldwide, and invasion of riparian wetlands by S. canadensis can reduce vegetation diversity and alter soil nutrient cycling. However, little is known about how S. canadensis invasion affects soil carbon cycle processes, such as soil respiration, in a riparian wetland. This study was conducted to investigate the effects of different degrees of S. canadensis invasion on soil respiration under different moisture conditions. Soil respiration rate (heterotrophic and autotrophic respiration) was measured using a closed-chamber method. S. canadensis invasion considerably reduced soil respiration under all moisture conditions. The inhibition effect on autotrophic respiration was higher than that on heterotrophic respiration. The water level gradient affects the soil autotrophic respiration, thereby affecting the soil respiration rate. The changes in soil respiration may be related to the alteration in the effective substrate of the soil substrate induced by the invasion of S. canadensis. While the effects of S. canadensis invasion were regulated by the fluctuation in moisture conditions. Our results implied that S. canadensis invasion could reduce the soil respiration, which further potentially affect the carbon sequestration in the riparian wetlands. Thus, the present study provided a reference for predicting the dynamics of carbon cycling during S. canadensis invasion and constituted a scientific basis for the sustainable development and management of riparian wetlands invaded by alien plants.