Urban green infrastructures (GI) are increasingly affected by environmental fluctuations which may impair photosynthetic performance and reduce ecosystem services. This study aimed to assess the health state of urban GI ecosystems in Florence, Italy, from May to October 2023, using different plant species (Arundo donax, Laurus nobilis and Artemisia verlotiorum) as bio-indicators monitored throughout their entire vegetative season. To this end, chlorophyll-a fluorescence (JIP-test), optical leaf traits, and meteorological indicators were integrated. Climate data showed frequent heat stress conditions, with 70–87

Global change is increasing the occurrence and extent of wildfires, with growing impacts on the environment and human health. As wildfires can alter soil microbial diversity and increase contaminant presence, bioremediation may support soil recovery. This study investigated the short-term direct and indirect effects of wildfire that occurred on July 24, 2022, in the village of Cinigiano (Tuscany, Italy). Three soil types were analyzed based on their fire exposure: a control soil not affected by the fire (CS), a soil located near the burned area but affected by ash and heat (NBS), and a soil within the burned area (BS). Soils were tested both in the solid phase and as elutriate, either untreated or treated for 15 days with effective microorganisms (EM), under short-term experimental conditions. Ecotoxicity assays were performed considering Lepidium sativum, Aliivibrio fischeri, Raphidocelis subcapitata and Daphnia magna; the quality index (TBI) was calculated for each condition (CS, NBS, BS, -EM/+EM). Biochemical stress responses in L. sativum were also assessed. Under the tested experimental conditions, the 15-day EM treatment was generally accompanied by a decrease in pH, while increased ecotoxicological hazard was observed in +EM-treated soils. Although long-term EM applications may support remediation over long time scales, these findings indicate that short-term EM application should also be carefully evaluated, given the potential increase in ecotoxicological hazard and the possible repercussions for organisms from different environmental compartments.

Although copper (Cu) is one of the essential micronutrients for plant metabolism, excess Cu induces oxidative stress and growth inhibition. In contrast, silicon (Si), despite not being considered an essential nutrient, plays a role in plant growth improvement and stress alleviation. This study aimed to assess the protective role of Si against Cu toxicity in olive shoots cv. Moraiolo cultured in vitro under different Cu and Si concentrations. Shoots were cultured on OM medium supplemented with 200 and 300 µM CuSO4, with or without 2 and 4 mM K2SiO3 for eight weeks. Cu stress significantly reduced the survival rate, biometric parameters, chlorophyll content, and macronutrient accumulation, while increasing Cu accumulation, oxidative stress markers, and antioxidant metabolites. Si supplementation alleviated these adverse effects, particularly at 2 mM under 200 µM Cu, by improving growth, chlorophyll content, nutrient balance, and antioxidant responses. Interestingly, Si alone promoted growth and physiological performance beyond control levels. However, the Si effect at 300 µM Cu was less pronounced, suggesting that Si-mediated amelioration depends on both Si dose and Cu concentration. These findings indicate that Si improves the physiological performance of olive microshoots under Cu stress. The protective effect of Si was dose-dependent, with 2 mM Si generally providing greater beneficial effects under moderate Cu stress.

To get further insights on the micro-nanoplastic (MNP) effects on plants, the aim of this study was to evaluate the response of hydroponically cultivated Arabidopsis thaliana to the presence of differentially colored polyethylene terephthalate (PET) particles. MNP impacts on the root organ were studied at a molecular level, with a special focus on the role of long non-coding RNAs (lncRNAS) in the regulation of gene expression after PET exposure. MNPs of transparent (Tr-PET) and blue (Bl-PET) material at environmentally realistic concentration caused a significant reduction in root length, while only Bl-PET significantly reduced rosette area. MNPs induced oxidative stress markers. Tr-PET upregulated genes involved in signaling of xenobiotics, whereas Bl-PET scarcely affected root transcriptomic profile, activating few gene categories for abiotic stresses. Regarding hormones, genes involved in ABA response were repressed, while brassinosteroid-related genes were differentially regulated by Tr-PET. Both MNPs, but especially Tr-PET, upregulated major latex protein-related genes. Plant molecular response to MNPs was linked to differential abundance of lncRNAs on both comparisons. Tr-PET affected the expression of much more lncRNAs than bl-PET (80 and 11 respectively). These lncRNAs were predicted to interact with several repressed protein-coding genes (i.e. glucosyltransferase UGT2, oxidative stress genes etc.), with possible effects on their regulation. A lncRNA (AT1G09297) interacted with CYP81D8, a key gene of cytochrome P450 gene family involved in xenobiotics detoxification. Two lncRNAs interacted with two members of repressed HSP (HSP90 and HSP17.4) family. Finally, genes involved in redox detoxification and stress responses were inhibited by the interaction with two microplastics-regulated lncRNAs. These data highlighted the need of investigating non-coding RNAs in the future in addition to the mostly studied protein coding transcriptome.

In olive micropropagation, Copper (Cu) promotes metabolic activity at optimal levels but exerts toxic effects and induces stress and cellular damage when present at excessive concentrations. The present study examined in vitro olive (cv. Moraiolo) shoot cultures under varying Cu concentrations to evaluate the impact of Cu-induced stress on shoot growth and development, as well as the associated physiological and biochemical tolerance mechanisms. Olive shoots were cultured on OM medium (as a control) supplemented with 50, 100, 200, or 300 mu M CuSO45H2O. Morphological and biochemical analyses showed that up to 50 mu M Cu did not cause visible stress symptoms or impair growth, while higher concentrations (100-300 mu M) significantly suppressed or inhibited vegetative growth, and caused a marked reduction in photosynthetic pigments. The contents of oxidative stress markers, hydrogen peroxide and malondialdehyde, increased with rising Cu concentrations, serving as reliable indicators of severe stress conditions. Non-enzymatic antioxidants, glutathione, ascorbic acid and proline, increased with higher Cu concentrations, playing a protective role against oxidative damage. These findings provide insight into the tolerance mechanisms of olive shoots under Cu stress, offering useful information for optimizing in vitro micropropagation and understanding Cu toxicity in plant tissue culture.

To unravel the complex interactions between microplastics (MPs), plants, and pathogens, Arabidopsis thaliana plants were grown for 3 weeks in soils containing polyethylene terephthalate (PET) or polyvinyl chloride (PVC) MPs (0.2% and 0.5% w/w), and leaves were then exposed to the PAMP (Pathogen-Associated Molecular Pattern) protein cerato-platanin (CP) or Botrytis cinerea conidia. PET caused a stimulation of stomatal conductance, and PVC decreased the aboveground biomass of A. thaliana plants. PVC (0.2%) triggered a primed state in A. thaliana, enhancing its response to B. cinerea infection and cerato-platanin. This was demonstrated by decreased lesion size, enhanced ROS generation, and elevated camalexin synthesis following PAMP elicitation, and increased levels of defensive isothiocyanate and phenylpropanoid metabolites. Our results indicate that MPs also affect soil structure, ionome balance, and specialised metabolite accumulation. However, MPs did not provide an unambiguous response, underscoring challenges in formulating a model of plant response to MPs when exposed to pathogens.

In the frame of bioeconomy and circular economy, wastewater sludge (WS) could be a good candidate for its use in agriculture as fertilizer, due to its high content of organic matter, N and P, but on the other hand, it is full of toxicants such as heavy metal, microplastics, detergent, antibiotics, and so on that can reach groundwater and water bodies in leachate form. In this study, we have investigated different sludge concentrations in the eluate form, combined and not with PVC on two different freshwater organisms Selenastrum capricornutum and Daphnia magna, using ecotoxicity tests. At the endpoint, we have evaluated inhibition growth rate, oxidative stress, and pigments production for S. capricornutum, while in case of D. magna, we have assessed organism immobilization and development. From our results, it emerged that at the higher WS concentration, there was not inhibition growth rate, while at oxidative stress, it was higher in algae treated with WS and PVC. Higher Chl-a production was shown for algae treated with 0.3 g/L of sludge coupled with PVC, where higher phaeopigments production were recorded for algae treated with 0.3 g/L of WS. D. magna has shown an opposite trend when compared with algae, where at the highest WS concentrations supplied was corresponding to an increased mortality explaned as the highest immobility percentage. Practitioner Points center dot Wastewater sludge is used in agriculture as fertilizer. center dot PVC microplastic presence and associate ecotoxicity was tested. center dot PVC presence increased oxidative stress in S. capricornutum. center dot D. magna was significantly affected by sludge concentrations supplied.

The effects of polyethylene terephthalate micro-nanoplastics (PET-MNPs) were tested on the model freshwater species Spirodela polyrhiza (L.) Schleid., with focus on possible particle-induced epigenetic effects (i.e. alteration of DNA methylation status). MNPs (size ∼ 200-300 nm) were produced as water dispersions from PET bottles through repeated cycles of homogenization and used to prepare N-medium at two environmentally relevant concentrations (∼0.05 g L-1 and ∼0.1 g L-1 of MNPs). After 10 days of exposure, a reduction in fresh and dry weight was observed in treated plants, even if the average specific growth rate for both frond number and area was not altered. Impaired growth was coupled with a MNP-induced decrease of chlorophyll fluorescence parameters (i.e. ΨETo and Piabs, indicators of photochemical efficiency) and starch concentration, as well as with alterations in plant ionomic profile and oxidative status. The methylation-sensitive amplification polymorphism (MSAP) technique was used to assess possible changes in DNA methylation levels induced by plastic particles. The analysis showed unusual hypermethylation in 5'-CCGG sites that could be implicated in DNA protection from dangerous agents (i.e. reactive oxygen species) or in the formation of new epialleles. This work represents the first evidence of MNP-induced epigenetic modifications in the plant world.

Sewage sludge has fertilizer properties and can supply a large amount of necessary nutrients to the crops, because it is full of organic matter, carbon, nitrogen and other nutrients, but on the other hand, it also contains a lot of toxic compounds, derived from its origin, such as heavy metals, antibiotics and microplastics. Effective microorganisms are a collection of naturally occurring beneficial microorganisms that are able to coexist and are commonly used in agriculture and gardening to improve plant performance and production. In this study, increasing concentrations of sewage sludge alone and added with effective microorganisms were evaluated in a short exposure on Lepidium sativum L. Parameters that were evaluated are: (i) percentage inhibition of germination, (ii) root length, (iii) biomass, (iv) soil pH, (v) total organic carbon and nitrogen both at soil and at root level. Results carried out from our experiment highlighted that effective microorganisms when coupled with sludge are able to restore biometric parameters by resetting seeds germinability inhibition and improving root elongation more than 50% when compared with plants added only with sludge, restoring the values almost of those to the control plants, as well as for soil pH values. Total organic carbon and total nitrogen are boosted at soil level almost at 50% when compared with the same concentrations added only with sludge, while at root level they appear decreased only in plants directly added with sludge treated with effective microorganisms.Clinical Trial Registration This research does not have a Clinical Trial Registration because no humans are been involved.

Solanum lycopersicum L., a crop grown worldwide with a high nutritional value for the human diet, was used to test the impact of microplastics on plant growth, productivity, and fruit quality. Two of the most represented microplastics in soils, polyethylene terephthalate (PET) and polyvinyl chloride (PVC), were tested. Plants were grown in pots with an environmentally realistic concentration of microplastics and, during the whole crop life cycle, photosynthetic parameters, number of flowers and fruits were monitored. At the end of the cultivation, plant biometry and ionome were evaluated, along with fruit production and quality. Both pollutants had negligible effects on shoot traits, with only PVC causing a significant reduction in shoot fresh weight. Despite an apparent low or no toxicity during the vegetative stage, both microplastics decreased the number of fruits and, in the case of PVC, also their fresh weights. The plastic polymer-induced decline in fruit production was coupled with wide variations in fruit ionome, with marked increases in Ni and Cd. By contrast there was a decline in the nutritionally valuable lycopene, total soluble solids, and total phenols. Altogether, our results reveal that microplastics can not only limit crop productivity but also negatively impact fruit quality and enhance the concentration of food safety hazards, thus raising concerns for their potential health risks for humans.

Arundo donax has been recognized as a promising crop for biomass production on marginal lands due to its superior productivity and stress tolerance. However, salt stress negatively impacts A. donax growth and photosynthesis. In this study, we tested whether the tolerance of A. donax to salinity stress can be enhanced by the addition of 5-aminolevulinic acid (ALA), a known promoter of plant growth and abiotic stress tolerance. Our results indicated that root exposure to ALA increased the ALA levels in leaves along the A. donax plant profile. ALA enhanced Na+ accumulation in the roots of salt-stressed plants and, at the same time, lowered Na+ concentration in leaves, while a reduced callose amount was found in the root tissue. ALA also improved the photosynthetic performance of salt-stressed apical leaves by stimulating stomatal opening and preventing an increase in the ratio between abscisic acid (ABA) and indol-3-acetic acid (IAA), without affecting leaf methanol emission and plant growth. Supply of ALA to the roots reduced isoprene fluxes from leaves of non-stressed plants, while it sustained isoprene fluxes along the profile of salt-stressed A. donax. Thus, ALA likely interacted with the methylerythritol 4-phosphate (MEP) pathway and modulate the synthesis of either ABA or isoprene under stressful conditions. Overall, our study highlights the effectiveness of ALA supply through soil fertirrigation in preserving the young apical developing leaves from the detrimental effects of salt stress, thus helping of A. donax to cope with salinity and favoring the recovery of the whole plant once the stress is removed.

Arundo donax L. is an invasive species that has been recently employed for biomass production due to its wellknown ability to colonize harsh environment. Based on previous observations, the present study investigated the potential role of phenylpropanoids and class III peroxidases to confer adaptation through biochemical and transcriptomic analysis in A. donax after Na+ and P excess supply, both in single stress and in combination, and after growth at low P level. The levels of hydrogen peroxide, flavonoids (i.e., quercetin, apigenin and kaempferol derivatives) and the activity of class III peroxidases, as well as the expression of several genes encoding for their enzymes involved in their biosynthesis, increased when Na+ was supplied in combination with P. These results suggest that those biomolecules are involved in the response of A. donax, to the presence of +Na and P in the soil. Moreover, even though at the sampling time no significant accumulation of lignin has been determined, the trend of accumulation of such metabolite and most of all the increase of several transcripts involved in its synthesis was found. This work for the first time indicates the need for further investigation devoted to elucidating whether the strengthening of cell walls via lignin synthesis is one of the mechanisms used by A. donax to adapt to harsh environments.

Microplastics (MPs) are ubiquitous pollutants that have also been detected in the aquatic ecosystems at high concentrations. The use of shellfish as bioindicators is widespread for assessing and monitoring the environmental quality in both freshwater and marine environments. On this path, biomarkers represent an effective tool in monitoring programs. This minireview would broaden the existing knowledge on biomarkers of MPs in the Mediterranean mussel Mytilus galloprovincialis. This species was selected as it is widely distributed across the Mediterranean Sea and used as a bioindicator to monitor the presence of MPs in the marine environment. The literature search returned only 11 studies, mainly related to oxidative stress biomarkers. Although certain biomarkers were explored to estimate the effects of MPs on M. galloprovincialis, a battery of standardized and validated biomarkers as well as the inclusion of new ones are needed in future studies to obtain more comparable and robust findings across the Mediterranean Sea.

In this study, Cucurbita pepo L., one of the most cultivated, consumed and economically important crop worldwide, was used as model plant to test the toxic effects of the four most abundant microplastics identified in contaminated soils, i.e. polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC), and polyethyleneterephthalate (PET). Cucurbita plants were grown in pots with increasing concentrations of the microplastics, then plant biometry, photosynthetic parameters and ionome of treated vs. untreated samples were compared to evaluate the toxicity of each plastic. All the pollutants impaired root and, especially, shoot growth. Specific and concentration-dependant effects of the different microplastics were found, including reduction in leaf size, chlorophyll content and photosynthetic efficiency, as well as changes in the micro- and macro-elemental profile. Among all the microplastics, PVC was identified as the most toxic and PE as the less toxic material. PVC decreased the dimensions of the leaf lamina, the values of the photosynthetic performance index and the plant iron concentration to a higher extent in respect to the other treatments. Microplastic toxicity exerted on the growth of C. pepo raises concerns about possible yield and economic loss, as well as for risks of a possible transfer into the food chain.

One of the main impacts of climate change on agriculture production is the dramatic increase of saline (Na + ) content in substrate, that will impair crop performance and productivity. Here we demonstrate how the application of smart technologies such as an in vivo sensor, termed bioristor, allows to continuously monitor in real-time the dynamic changes of ion concentration in the sap of Arundo donax L. (common name giant reed or giant cane), when exposed to a progressive salinity stress. Data collected in vivo by bioristor sensors inserted at two different heights into A. donax stems enabled us to detect the early phases of stress response upon increasing salinity. Indeed, the continuous time-series of data recorded by the bioristor returned a specific signal which correlated with Na + content in leaves of Na-stressed plants, opening a new perspective for its application as a tool for in vivo plant phenotyping and selection of genotypes more suitable for the exploitation of saline soils.

This study evaluated the chronic toxicity (30 days) of different sizes of polyethylene terephthalate (PET) microplastics (60-3000 mu m) provided alone or in combination with acid rain, on garden cress (Lepidium sativum). Both biometrical and physiological traits have been evaluated: i) percentage inhibition of seed germination, plant height, leaf number and fresh biomass production; ii) oxidative stress responses (hydrogen peroxide; ascorbic acid and glutathione production); iii) impairment in photosynthetic machinery in term of pigments production; iv) aminolevulinic acid and proline production. Results highlighted that different sizes of PET, alone or in combination with acid rain, are able to negatively affect both biometrical and physiological plant traits. In particular, the lower size of microplastics is able to negatively affect growth and development, as well as to trigger the oxidative burst. Regarding the pigments production, PET coupled with acid rain, induced a higher production of Chl-b, and an inhibition of aminolevulinic acid. (C) 2021 Elsevier Ltd. All rights reserved.

In this study, for the first time, acute and chronic toxicity caused by four different kinds of microplastics: polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC), and a commercial mixture (PE + PVC) on Lepidium sativum were evaluated. Parameters considered were: i) biometric parameters (e.g. percentage inhibition of seed germination, plant height, leaf number and fresh biomass productions); and ii) oxidative stress (e.g. levels of hydrogen peroxide, glutathione, and ascorbic acid). On plants exposed to chronic stress chlorophylls, carotenoids, aminolaevulinic acid, and proline productions were, also, evaluated. PVC resulted the most toxic than other plastic materials tested. This study represents the first paper highlighting microplastics are able to produce oxidative burst in tested plants and could represent an important starting point for future researches on biochemical effects of microplastic in terrestrial environments such as agroecosystems.

Arundo donax L. is an invasive grass species with high tolerance to a wide range of environmental stresses. The response of potted A. donax plants to soil stress characterized by prolonged exposure (43 days) to salinity (+Na), to high concentration of phosphorus (+P), and to the combination of high Na and P (+NaP) followed by 14 days of recovery under optimal nutrient solution, was investigated along the entire time-course of the experiment. After an exposure of 43 days, salinity induced a progressive decline in stomatal conductance that hampered A. donax growth through diffusional limitations to photosynthesis and, when combined with high P, reduced the electron transport rate. Isoprene emission from A. donax leaves was stimulated as Na+ concentration raised in leaves. Prolonged growth in P-enriched substrate did not significantly affect A. donax performance, but decreased isoprene emission from leaves. Prolonged exposure of A. donax to + NaP increased the leaf level of H2O2, stimulated the production of carbohydrates, phenylpropanoids, zeaxanthin and increased the de-epoxidation state of the xanthophylls. This might have resulted in a higher stress tolerance that allowed a fast and full recovery following stress relief. Moreover, the high amount of ABA-glucose ester accumulated in leaves of A. donax exposed to + NaP might have favored stomata re-opening further sustaining the observed prompt recovery of photosynthesis. Therefore, prolonged exposure to high P exacerbated the negative effects of salt stress in A. donax plants photosynthetic performances, but enhanced activation of physiological mechanisms that allowed a prompt and full recovery after stress.

Plastics enter in terrestrial natural system primarily by agricultural purposes, while acid rain is the result of anthropogenic activities. The synergistic effects of microplastics and acid rain on plant growth are not known. In this study, different sizes of polyethylene terephthalate (PET) and acid rain are tested on Lepidium sativum, in two separate experimental sets. In the first one we treated plants only with PET, in the second one we used PET and acid rain together. In both experimentations we analyzed: i) plant biometrical parameters (shoot height, leaf number, percentage inhibition of seed germination, fresh biomass), and ii) oxidative stress responses (hydrogen peroxide; ascorbic acid and glutathione). Results carried out from our experiments highlighted that different sizes of polyethylene terephthalate are able to affect plant growth and physiological responses, with or without acid rain supplied during acute toxicity (6 days). Short description: This study showed that different sizes of PET microplastics affect physiological and biometrical responses of Lepidum sativum seedlings, with or without acid rain; roots and leaves responded differently.