Phytoremediation by Eremanthus crotonoides and Inga striata decay atrazine and clomazone residues in the soil

Clomazone exposure-driven photosynthetic responses plasticity of Pontederia crassipes

Clomazone is known to contaminate aquatic environments and have a negative impact on macrophytes. However, recent reports suggests that Pontederia crassipes Mart. can withstand clomazone exposure while maintaining growth rates. We hypothesized that this maintenance of growth is supported by photosynthetic plasticity of old leaves (developed before herbicide application), while new leaves (developed after application) exhibit phytotoxic symptoms. To investigate, two experiments were conducted with doses ranging from 0.1 mg L-1 to 0.5 mg L-1 plus untreated controls. Various parameters were measured in old and new leaves over 7, 12, and 15 d post-application, including visual symptoms, chlorophyll index, photosynthetic pigments, chlorophyll fluorescence, gas exchange, glycolate oxidase activity, carbohydrate content, leaf epidermis anatomy, and growth parameters. Clomazone exposure induced chlorosis, particularly in new leaves across all doses. These visual symptoms were accompanied by stomatal closure, restricting gas exchange and CO2 fixation, leading to reduced photosynthetic rates and carbohydrate synthesis. However, clomazone did not affect old leaves, which maintained photosynthetic activity, sustaining essential metabolic processes of the plant, including reproductive functions. By ensuring high reproductive rates and metabolic continuity, old leaves supported the species' persistence despite clomazone presence.

Sensitivity and antioxidant response of forest species seedlings to the atrazine under simulated conditions of subsurface water contamination

Atrazine is an herbicide with a high soil leaching capacity, contaminating subsurface water sources. Once the water table is contaminated, riparian species can be exposed to atrazine. In this way, understanding the impacts of this exposure must be evaluated for planning strategies that minimize the effects of this herbicide on native forest species. We aimed to evaluate forest species' sensitivity and antioxidant response to exposure to subsurface waters contaminated with atrazine, as well the dissipation this herbicide. The experiment was conducted in a greenhouse in a completely randomized design, with three replications and one plant per experimental unit. The treatments were arranged in a 2 × 10 factorial. The first factor corresponded to the presence or absence (control) of the atrazine in the subsurface water. The second factor comprised 10 forest species: Amburana cearensis, Anadenanthera macrocarpa, Bauhinia cheilantha, Enterolobium contortisiliquum, Hymenaea courbaril, Libidibia ferrea, Mimosa caesalpiniifolia, Mimosa tenuiflora, Myracrodruon urundeuva, and Tabebuia aurea. The forest species studied showed different sensitivity levels to atrazine in subsurface water. A. cearensis and B. cheilantha species do not have efficient antioxidant systems to prevent severe oxidative damage. The species A. macrocarpa, E. contortisiliquum, L. ferrea, and M. caesalpiniifolia are moderately affected by atrazine. H. courbaril, M. urundeuva, and T. aurea showed greater tolerance to atrazine due to the action of the antioxidant system of these species, avoiding membrane degradation events linked to the production of reactive oxygen species (ROS). Among the forest species, H. courbaril has the most significant remedial potential due to its greater tolerance and reduced atrazine concentrations in the soil.

Investigation of the Persistence, Toxicological Effects, and Ecological Issues of S-Triazine Herbicides and Their Biodegradation Using Emerging Technologies: A Review

S-triazines are a group of herbicides that are extensively applied to control broadleaf weeds and grasses in agricultural production. They are mainly taken up through plant roots and are transformed by xylem tissues throughout the plant system. They are highly persistent and have a long half-life in the environment. Due to imprudent use, their toxic residues have enormously increased in the last few years and are frequently detected in food commodities, which causes chronic diseases in humans and mammals. However, for the safety of the environment and the diversity of living organisms, the removal of s-triazine herbicides has received widespread attention. In this review, the degradation of s-triazine herbicides and their intermediates by indigenous microbial species, genes, enzymes, plants, and nanoparticles are systematically investigated. The hydrolytic degradation of substituents on the s-triazine ring is catalyzed by enzymes from the amidohydrolase superfamily and yields cyanuric acid as an intermediate. Cyanuric acid is further metabolized into ammonia and carbon dioxide. Microbial-free cells efficiently degrade s-triazine herbicides in laboratory as well as field trials. Additionally, the combinatorial approach of nanomaterials with indigenous microbes has vast potential and considered sustainable for removing toxic residues in the agroecosystem. Due to their smaller size and unique properties, they are equally distributed in sediments, soil, water bodies, and even small crevices. Finally, this paper highlights the implementation of bioinformatics and molecular tools, which provide a myriad of new methods to monitor the biodegradation of s-triazine herbicides and help to identify the diverse number of microbial communities that actively participate in the biodegradation process.

Phytoremediation: A green and low-cost technology to remediate herbicides in the environment

Pesticide dependence is one of the main disadvantages of agriculture. Despite the advances in biological control and integrated management of plant pests and diseases in recent years, herbicides are still essential for weed control and constitute the main class of pesticides worldwide. Herbicide residues in water, soil, air, and non-target organisms are among the biggest agricultural and environmental sustainability obstacles. Therefore, we suggest an environmentally viable alternative to reduce the harmful effects of herbicide residues, a technology called phytoremediation. Remediating plants were grouped into herbaceous, arboreal, and aquatic macrophytes. Phytoremediation can reduce the loss of at least 50% of all herbicide residues to the environment. Among the herbaceous species reported as phytoremediators of herbicides, the Fabaceae family was mentioned in more than 50% of reports. This family is also among the main species of trees reported. Regarding the most reported groups of herbicides, it is observed that most of them, regardless of the group of plants, are triazines. Processes such as extraction or accumulation are the best known and reported for most herbicides. The phytoremediation may be effective against chronic or unknown herbicide toxicity. This tool can be included in proposals for management plans and specific legislation in countries, guaranteeing public policies to maintain environmental quality.

Rapid and sensitive detection of clomazone in potato and pumpkin samples using a gold nanoparticle-based lateral-flow strip

In this study, an ultrasensitive monoclonal antibody (mAb) was produced and used to develop a gold nanoparticle-based lateral flow immunochromatographic (ICA) strip for screening of clomazone (CLO) in potato and pumpkin samples. With assayed by indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) method, the mAb belonging of IgG2 subclass showed a half-maximal inhibitory concentration (IC50) of 3.47 ng/mL and a linear range of detection of 0.43-28.09 ng/mL. A cross-reactivity test revealed that the mAb had good specificity for CLO. The strip assay had a visual limit of detection (LOD) of 5 µg/kg and a cut-off value of 50 µg/kg for CLO pumpkin samples (potato samples was 100 µg/kg) when evaluated with the naked eye. The results were consistent with ic-ELISA and high performance liquid chromatography tandem mass spectrometry (HPLC-MS). Thus, this ICA strip assay represents a potentially tool for on-site and rapid initial detection of CLO in potato and pumpkin samples.

Water contamination with atrazine: is nitric oxide able to improve Pistia stratiotes phytoremediation capacity?

Atrazine is an herbicide commonly used in several countries. Due to its long half-life, associated with its use in large scales, atrazine residues remain as environmental pollutants in water bodies. Phytoremediation is often pointed out as an interesting approach to remove atrazine from the aquatic environment, but its practical application is limited by the high toxicity of this herbicide. Here, we characterize the damages triggered by atrazine in Pistia stratiotes, evaluating the role of nitric oxide (NO), a cell-signaling molecule, in increasing the tolerance to the pollutant and the phytoremediation potential of this species. Pistia stratiotes plants were exposed to four treatments: Control; Sodium nitroprusside (SNP) (0.05 mg L^-1); Atrazine (ATZ) (150 μg L^-1) and ATZ + SNP. The plants remained under those conditions for 24 h for biochemical and physiological analysis and 3 days for the evaluation of relative growth rate. The presence of atrazine in plant cells triggered a series of biochemical and physiological damages, such as the increase in the generation of reactive oxygen species, damages to cell membranes, photosynthesis impairment, and negative carbon balance. Despite this, the plants maintained greater growth rates than other aquatic macrophytes exposed to atrazine and showed high bioconcentration and translocation factors. The addition of SNP, a NO donor, decreased the herbicide toxicity, with an increase of over 60% in the IC₅₀ value (Inhibitor Concentration). Indeed, the NO signaling action was able to increase the tolerance of plants to atrazine, which resulted in increments in pollutant uptake and translocation, with the maintenance of overall cell (e.g. membranes) and organs (root system) structure, and the functioning of central physiological processes (e.g. photosynthesis). These factors allowed for more quickly and efficient removal of the pollutant from the environment, reducing costs, and increasing the viability of the phytoremediation process.