Arsenic (As) is a highly toxic metalloid adversely affecting the environment, human health, and crop productivity. The present study assessed the synergistic effects of salinity and As on photosynthetic attributes, stomatal regulations, and metabolomics responses of the xero-halophyte Salvadora persica to decipher the As-salinity cross-tolerance mechanisms and to identify the potential metabolites/metabolic pathways involved in cross-tolerance of As with salinity. Salinity and As stress-induced significant stomatal closure in S. persica suggests an adaptive response to decrease water loss through transpiration. NaCl supplementation improved the net photosynthetic rate (by +39%), stomatal conductance (by +190%), water use efficiency (by +55%), photochemical quenching (by +37%), and electron transfer rate (54%) under As stress as compared to solitary As treatment. Our results imply that both stomatal and non-stomatal factors account for a reduction in photosynthesis under high salinity and As stress conditions. A total of 64 metabolites were identified in S. persica under salinity and/or As stress, and up-regulation of various metabolites support early As-salinity stress tolerance in S. persica by improving antioxidative defense and ROS detoxification. The primary metabolites such as polyphenols (caffeic acid, catechin, gallic acid, coumaric acid, rosmarinic acid, and cinnamic acid), amino acids (glutamic acid, cysteine, glycine, lysine, phenylalanine, and tyrosine), citrate cycle intermediates (malic acid, oxalic acid, and α-ketoglutaric acid), and most of the phytohormones accumulated at higher levels under combined treatment of As + NaCl compared to solitary treatment of As. Moreover, exogenous salinity increased glutamate, glycine, and cysteine, which may induce higher synthesis of GSH-PCs in S. persica. The metabolic pathways that were significantly affected in response to salinity and/or As include inositol phosphate metabolism, citrate cycle, glyoxylate and dicarboxylate metabolism, amino acid metabolism, and glutathione metabolism. Our findings indicate that inflections of various metabolites and metabolic pathways facilitate S. persica to withstand and grow optimally even under high salinity and As conditions. Moreover, the addition of salt enhanced the arsenic tolerance proficiency of this halophyte.

The present study reports on the synthesis of Cu-bismuth oxide (CuBi₂O₄)–based nanorods by using a simple co-precipitation method for the photocatalytic degradation of caffeic acid (CA). The incorporation of Cu metal ions during the synthesis of CuBi₂O₄ nanorods might be advantageous to avoid the aggregation and control the leach out of metal ions. The calculated bandgap values of ~ 1.04, 1.02, and 0.94 eV were observed for CuBi₂O₄ with different amounts of Cu 1.0, 0.50, and 0.25 g, respectively. Varying the quantity of Cu metal ions easily tuned the bandgap value within the CuBi₂O₄-based nanorods. However, a further decrease in the bandgap value increased the recombination rate, and the less photocatalyst performance was observed. The CA degradation could be explained based on the species distribution. The CA pKa was mainly located between pKa₁ and pKa₂ of 4.43 and 8.6, respectively. The Cu within the CuBi₂O₄-based nanorods changed the electronic properties and the antibacterial ability. Therefore, the synthesized CuBi₂O₄-based nanorod cluster might be a promising material for the photocatalytic degradation of CA.

Use of herbicides is one of the most preferred options for crop protection against weeds. Imazamox is an imidazolinone (IMI)-group herbicide, and even low concentrations of imazamox might exhibit high biological activities on soil and plants. Therefore, in contrast to the conventional types of sunflowers that are sensitive to IMI-group herbicides, sunflowers that are resistive to IMI-group herbicides were also developed in recent years. In this study, the effect of imazamox on some physiological and genetic parameters of two types of sunflowers that are sensitive and resistant to IMI-group herbicides is comparatively investigated. For this purpose, three concentrations of imazamox (0.82, 1.64 and 2.45 mM, respectively) were applied on the two types of sunflower (i.e. SN:8 as IMI-sensitive type and SN:9 as IMI-resistant type, respectively). In addition, the physiological and molecular effects of IMI on antioxidant enzymes (such as superoxide dismutase (SOD), catalase, glutathione S-transferase (GST)), heat shock proteins (such as HSP26, HSP60, HSP70), phenolic contents (coumaric acid, caffeic acid, ferulic acid), phytohormone levels (indole-3-acetic acid, jasmonic acid (JA), salicylic acid (SA)) and accumulation of pesticides in the leaf tissue of sunflowers were analysed by qRT-PCR and LC MS/MS analysis. In this study, the pesticide concentration of resistant-type SN9 was significantly greater than that of SN8 with the application of 1.64–2.45 mM of imazamox, and the total pesticide amounts were 1.6 and 1.8 times significantly higher in leaf tissues, respectively. This pesticide accumulation led to an imbalance in the phytohormone and phenolic levels, increased levels of unfolded or misfolded proteins, and selective reduction of the GST, SA and JA levels in the two types of sunflowers. However, SN9 significantly responded to the pesticide accumulation via the overexpression of mitochondrial chaperone HSP60 (16.15-fold) and stress-specific HSP70 (54.46-fold), as well as higher SOD expression and SA and JA levels. In particular, by the application of high-dose IMI, our data revealed strong protein chaperone response, a high level of SOD expression, and finally the crosstalk of SA and JA, and these physiological and molecular phenomena can be indicative of pesticide-induced stress in SN9. The study suggested that high-concentration imazamox treatment induces some physiological and genetic changes at the phytotoxic level on not only IMI sensitive type but also resistant type.

Soil pollution is a worldwide issue and has a strong impact on ecosystems. Metal(loid)s have toxic effects on plants and affect various plant life traits. That is why metal(loid) polluted soils need to be remediated. As a remediation solution, phytoremediation, which uses plants to reduce the toxicity and risk of polluted soils, has been proposed. Moreover, flax (Linum usitatissimum L.) has been suggested as a potential phytoremediation plant, due to its antioxidant systems, which can lower the production of reactive oxygen species and can also chelate metal(loid)s. However, the high metal(loid) toxicity associated with the low fertility of the polluted soils render vegetation difficult to establish. Therefore, amendments, such as biochar, need to be applied to improve soil conditions and immobilize metal(loid)s. Here, we analyzed the growth parameters and oxidative stress biomarkers (ROS production, membrane lipid peroxidation, protein carbonylation and 8-oxoGuanine formation) of five different flax cultivars when grown on a real contaminated soil condition, and in the presence of a biochar amendment. Significant correlations were observed between plant growth, tolerance to oxidative stress, and reprogramming of phytochemical accumulation. A clear genotype-dependent response to metal(loid) stress was observed. It was demonstrated that some phenylpropanoids such as benzoic acid, caffeic acid, lariciresinol, and kaempferol played a key role in the tolerance to the metal(loid)-induced oxidative stress. According to these results, it appeared that some flax genotypes, i.e., Angora and Baikal, could be well adapted for the phytoremediation of metal(loid) polluted soils as a consequence of their adaptation to oxidative stress.

This study proposed the optimization of a laccase-mediator system to reduce pesticide levels (bentazone, carbofuran, diuron, clomazone, tebuconazole, and pyraclostrobin) on aqueous medium. Firstly, the mediator concentration of 1 mM was established (average removal of 36%). After that, seven redox-mediating compounds, namely, 2,20-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, caffeic acid, chlorogenic acid, p-coumaric acid, ferulic acid, gallic acid, protocatechuic acid, and vanillin, were compared regarding their removal efficiency. The highest removal (77%) was achieved with the laccase-vanillin system. After this screening, the optimization was carried out by a 2² full factorial design. Variables under study were the enzyme (laccase) activity and vanillin concentration. Maximum removal (53–85%) was achieved with 0.95 U/mL laccase and 1.8 mM vanillin. Pesticide removal in reaction media was fitted to the first-order kinetics equation with an average half-time life of 2.2 h. This is the first study of the use of this natural compound as a mediator in the degradation of the pesticides under investigation. The results of this study contribute, with alternative methods, to decrease pesticide levels since they are highly persistent in aqueous samples and, as a result, mitigate the environmental impact.

In this work, the potential of activated carbon to remove caffeic and chlorogenic acids in aqueous solution was investigated. The study focused on evaluating the single and binary adsorption equilibrium, as well as investigating the mass transfer resistances present during the process by applying diffusional models for a future scale-up of the process. For both compounds, the single adsorption equilibrium was studied at pH values of 3, 5, and 7. The experimental adsorption isotherms were interpreted using the Langmuir and Freundlich models, obtaining maximum adsorption capacities of 1.33 and 1.62 mmol/g for caffeic and chlorogenic acid, respectively. It was found that the adsorption mechanisms for both compounds were derived from π-π, electrostatic, and H-bonding interactions. Also, the binary adsorption equilibrium was performed, and the experimental data were interpreted using the extended multicomponent Langmuir model. The results evidenced that the binary adsorption of caffeic acid and chlorogenic acid is antagonistic in nature. Finally, the experimental adsorption rate data were interpreted by an external mass transport model and a diffusional model, finding that the overall adsorption rate is governed by intraparticle diffusion. Moreover, the surface and pore volume diffusion mechanisms were meaningful.

Ecophysiological and antioxidant traits were evaluated in sage (Salvia officinalis) plants exposed to 120 ppb of ozone for 90 consecutive days (5 h day⁻¹). At the end of fumigation, plants showed slight leaf yellowing that could be considered the first visual symptom of leaf senescence. Ozone-stressed leaves showed (1) reduced photosynthetic activity (−70 % at the end of exposure), (2) chlorophyll loss (−59 and −56 % of chlorophyll a and b concentrations, starting from 30 days from the beginning of exposure), and (3) cellular water deficit (−12 % of the relative water content at the end of the fumigation). These phenomena are indicative of oxidative stress in the chloroplasts (as confirmed by the strong degradation of β-carotene) despite the photoprotection conferred by xanthophyll cycle [as demonstrated by the significant rise of de-epoxidation index, reaching the maximum value at the end of the treatment (+69 %)], antioxidant compounds [as confirmed by the increase of phenols (in particular caffeic acid and rosmarinic acid)], and water-soluble carbohydrates (especially monosaccharides). By means of combined ecophysiological and biochemical approaches, this study demonstrates that S. officinalis is able to activate an adaptive survival mechanism allowing the plant to complete its life cycle even under oxidative stressful conditions.

Liriodendron tulipifera (known as the tulip tree) is a woody species that has been previously classified as sensitive to ozone (O₃) in terms of visible leaf injuries and photosynthetic primary reactions. The objective of this work is to give a thorough description of the detoxification mechanisms that are at the basis of O₃ sensitivity. Biochemical and molecular markers were used to characterize the response of 1-year-old saplings exposed to O₃ (120 ppb, 5 h day⁻¹, for 45 consecutive days) under controlled conditions. O₃ effects resulted in a less efficient metabolism of Halliwell-Asada cycle as confirmed by the diminished capacity to convert the oxidized forms of ascorbate and glutathione in the reduced ones (AsA and GSH, respectively). The reduced activity of AsA and GSH regenerating enzymes indicates that de novo AsA biosynthesis occurred. This compound could be a cofactor of several plant-specific enzymes that are involved in the early part of the phenylpropanoid and flavonoid biosynthesis pathway, as confirmed by the significant rise of PAL activity (+75%). The induction of the defence-related secondary metabolites (in particular, rutin and caffeic acid were about threefold higher) and the concomitant increase in transcript levels of PAL and CHS genes (+120 and 30%, respectively) suggest that L. tulipifera utilized this route in order to partially counteract the O₃-induced oxidative damage.

Plants in Brassica genus have been found to possess strong allelopathic potential. They may inhibit seed germination and emergence of subsequent crops following them in a rotation system. Series of laboratory and greenhouse experiments were conducted to determine the allelopathic impacts of Brassica napus L. against mung bean. We studied (1) the effects of aqueous extract (5%) of different plant parts (root, stem, leaf, flower, and whole plant) of B. napus, (2) the effects of leaf and flower extracts of B. napus at 0, 1, 2, 3, and 4% concentrations, and (3) the effect of residues of different B. napus plant parts and decomposition periods (0, 7, 14, and 21 days) on germination and seedling growth of mung bean. Various types of phenolics including quercitin, chlorogenic acid, p-coumeric acid, m-coumaric acid, benzoic acid, caffeic acid, syringic acid, vanillic acid, ferulic acid, cinamic acid, and gallic acid were identified in plant parts of B. napus. Among aqueous extracts of various plant parts, leaf and flower were found to have stronger inhibitory effects on germination and seedling growth traits of mung bean, higher concentrations were more toxic. The decomposition period changed the phtotoxic effect of residues, more inhibitory effect was shown at 14 days decomposition while decomposition for 21 days reduced inhibitory effect. The more total water-soluble phenolic was found in 5% (w/v) aqueous extract and 5% (w/w) residues of B. napus flowers at 14 days of decomposition (89.80 and 10.47 mg L⁻¹), respectively. The strong inhibitory effects of B. napus should be managed when followed in rotation.

Olive mill wastewater (OMWW) is claimed to be one of the most polluting effluents produced by agro-food industries, providing high contaminants load that encase cytotoxic agents such as phenolic and polyphenolic compounds. Therefore, a significant and continuous stress episode is induced once the mixed liquor of the wastewater treatment plants (WWTP’s) is being exposed to OMWW. The use of bio-augmentation treatment procedures can be useful to eliminate or reduce such stress episodes. In this study, we have estimated the use of autochthonous biomass implementation within small bioreactor platform (SBP) particles as a bio-augmentation method to challenge against WWTPs stress episodes. Our results showed that SBP particles significantly reduced the presence of various phenolics: tannic, gallic and caffeic acid in a synthetic medium and in crude OMWW matrix. Moreover, the SBP particles succeeded to biodegrade a very high concentration of phenol blend (3000 mg L⁻¹). Our findings indicated that the presence of the SBP microfiltration membrane has reduced the phenol biodegradation rate by 50 % compared to the same suspended culture. Despite the observed reduction in biodegradation rate, encapsulation in a confined environment can offer significant values such as overcoming the grazing forcers and dilution, thus achieving a long-term sufficient biomass. The potential for reducing stress episodes caused by cytotoxic agents through bio-augmentation treatment procedure using the SBP technology is discussed.