The pesticide thiamethoxam induced toxicity in Brassica juncea and its detoxification by Pseudomonas putida through biochemical and molecular modifications

Insights into the synergistic effects of exogenous glycine betaine on the multiphase metabolism of oxyfluorfen in Oryza sativa for reducing environmental risks

Glycine betaine (GB), a secondary metabolite that regulates plant responses to biotic and abiotic stresses, may help reduce pesticide phytotoxicity, but this fact remains unestablished. This study investigated the physiological response of rice (Oryza sativa) to six dosages of oxyfluorfen (OFF) (0-0.25 mg/L) and two concentrations of GB (0 and 175 mg/L). GB treatment counteracted the considerable decrease in rice seedling growth caused by OFF treatment at doses higher than 0.15 mg/L. The biochemical processes and catalytic events associated with OFF-triggered degradation in rice were investigated using RNA-Seq-LC-Q-TOF-HRMS/MS after six rice root and shoot libraries were created and subjected to either OFF or OFF-GB. Rice treated with both GB and an ecologically relevant dose of OFF showed a marked upregulation of 1039 root genes and 111 shoot genes compared with those treated with OFF alone. Multiple OFF-degradative enzymes implicated in molecular metabolism and xenobiotic tolerance to environmental stress were identified by gene enrichment analysis. In comparison to treated with 0.25 mg/L OFF alone, exogenous GB administration decreased OFF accumulation, with the OFF concentration in roots being 44.47 % and in shoots being 51.03 %. The production of essential enzymes involved in the OFF decay process was attributed to certain genes with variable expression, including cytochrome P450, methyltransferase, glycosyltransferases, and acetyltransferases. Using LC-Q-TOF-HRMS/MS, 3 metabolites and 16 conjugates were identified in metabolic pathways including hydrolysis, acetylation, glycosylation, and interaction with amino acids in order to enhance OFF-degradative metabolism. All things considered, by reducing phytotoxicity and OFF buildup, external GB treatment can increase rice's resistance to oxidative stress caused by OFF. This study offers valuable insights into the function of GB in enhancing OFF degradation, which may have ramifications for designing genotypes that maximize OFF accumulation in rice crops and promote OFF degradation in paddy crops.

Toxicological impact of Thiamethoxam on adult male rats: Histopathological, biochemical, and oxidative DNA damage assessment

Background

Thiamethoxam (TMX), a widely used second-generation neonicotinoid insecticide, has raised concerns due to its toxic effects on non-target species, including mammals. Its prolonged use is associated with hepatotoxicity, nephrotoxicity, and reproductive damage.

Objectives

This study evaluates the dose-dependent biochemical, histopathological, and genetic toxic effects of TMX in male albino rats, emphasizing its impact on the liver, kidney, and reproductive systems.

Materials and methods

Forty male Wistar albino rats were assigned to control and three experimental groups treated with TMX at 26, 39, and 78 mg/kg/day over eight weeks. Key biochemical markers such as Alanine transaminase (ALT), Aspartate transaminase (AST), urea, creatinine and oxidative stress indicators (Catalase (CAT), Glutathione (GSH), Malondialdehyde (MDA), and reproductive parameters (testosterone, sperm count, and motility) were analyzed. Histopathological examination of the liver, kidney, and testes was performed, alongside evaluation of Deoxyribonucleic Acid (DNA) damage in testicular tissue.

Results

TMX exposure caused significant dose-dependent increases in liver and kidney function markers and oxidative stress. Reproductive toxicity was evident, with reduced testosterone levels, impaired sperm parameters, and histopathological damage to testicular tissue. Notably, TMX induced oxidative DNA damage in testicular tissue, as indicated by increased levels of 8-hydroxy-2'-deoxyguanosine.

Conclusions

This study highlights TMX's systemic toxicity in a dose-dependent manner, with oxidative stress and DNA damage as key mechanisms. The findings underscore the need for stricter regulatory measures and further exploration of protective strategies to mitigate TMX-induced toxicity.

Multifaceted investigation of esfenvalerate-induced toxicity on Allium cepa L

The objective of this study was to assess the toxicity of the insecticide esfenvalerate in Allium cepa, employing a multifaceted methodology. For this purpose, A. cepa bulbs were organized into four groups, one of which served as the control. The control group was exposed to tap water, while the remaining three groups were exposed to esfenvalerate at concentrations of 0.33 mg/L, 0.64 mg/L and 0.98 mg/L, respectively. The application of the highest dose of 0.98 mg/L esfenvalerate resulted in a significant decrease in physiological parameters, including a 51% reduction in rooting percentage, an 85.3% decrease in root elongation, and a 54.3% decrease in weight gain (p < 0.05). In the esfenvalerate-treated group (0.98 mg/L), a 45.7% decrease in mitotic index was observed, while a significant increase in chromosomal aberrations and micronucleus formation was observed compared to the control group (p < 0.05). The most frequently observed chromosomal abnormalities due to esfenvalerate were sticky chromosome, vagrant chromosome, fragment, unequal distribution of chromatin, bridge, vacuolated nucleus, reverse polarization and multipolar anaphase. Insecticide application could significantly increase the percentage of DNA tails up to 48.3%, as determined by the Comet test (p < 0.05). Exposure to 0.98 mg/L esfenvalerate increased malondialdehyde level (2.75-fold), proline level (1.96-fold), superoxide dismutase activity (1.35-fold), and catalase activity (1.69-fold) while reducing chlorophyll a level (58.18%) and chlorophyll b level (70.35%) (p < 0.05). Molecular docking analysis revealed that esfenvalerate can interact with tubulins, DNA topoisomerases, glutamate-1-semialdehyde aminotransferase, protochlorophyllide reductase and DNA molecules. Epidermis and cortex cell damages, cortex cell wall thickening, material accumulation in cortex cells and flattened cell nucleus were recorded as meristematic cell damages due to esfenvalerate. The toxicological profile of esfenvalerate on A. cepa exhibited dose dependence. While esfenvalerate-induced oxidative stress is the most probable cause of toxicity, direct interaction with DNA and other molecules that play a crucial role in maintaining cell integrity may also be among the mechanisms of toxicity. The study's findings emphasize that esfenvalerate poses a risk to non-target organisms, underscoring the need for a reassessment of its regulations and further research into its toxicity.

Integrated transcriptomic and physio-molecular studies unveil the melatonin and PGPR induced protection to photosynthetic attributes in Brassica juncea L. under cadmium toxicity

Cd is highly mobile, non-essential trace element, that has become serious environmental issue due to its elevated concentration in soil. The present study was taken up to work out salutary effect of melatonin (Mlt) and PGPR ((Pseudomonas putida (Pp), Pseudomonas fluorescens (Pf) in 10 days old Cd stressed (0.3 mM) Brassica juncea L. seedlings. The present work investigated growth characteristics, photosynthetic pigments, secondary metabolites in melatonin-PGPR inoculated B. juncea seedlings. It was backed by molecular studies entailing RT-PCR and transcriptomic analyses. Our results revealed, substantial increase in photosynthetic pigments and secondary metabolites, after treatment with melatonin, P.putida, P. fluorescens in Cd stressed B. juncea seedlings, further validated with transcriptome analysis. Comparative transcriptome analyses identified 455, 5953, 3368, 2238 upregulated and 4921, 430, 137, 27 down regulated DEGs, Cn-vs-Cd, Cd-vs-Mlt, Cd-vs-Mlt-Pp-Pf, Cd-vs-Mlt-Pp-Pf-Cd comparative groups respectively. In depth exploration of genome analyses (Gene ontology, Kyoto encyclopaedia of genes), revealed that Cd modifies the expression patterns of most DEGs mainly associated to photosystem and chlorophyll synthesis. Also, gene expression studies for key photosynthetic genes (psb A, psb B, CHS, PAL, and PSY) suggested enhanced expression in melatonin-rhizobacteria treated Cd stressed B. juncea seedlings. Overall, results provide new insights into probable mechanism of Mlt-PGPR induced protection to photosynthesis in Cd stressed B. juncea plants.

Deciphering the role of nitric oxide in mitigation of systemic fungicide induced growth inhibition and oxidative damage in wheat

Consento (CON) poses a significant environmental hazard as a systemic fungicide, adversely affecting the health of non-target organisms. Nitric oxide (NO), a signaling molecule, is known to play a crucial role in plant physiology and abiotic stress tolerance. However, whether NO plays any role to enhance fungicide CON tolerance in wheat seedlings is yet unclear. Therefore, we conducted a hydroponic experiment i) to investigate the morpho-physio-biochemical changes of wheat seedlings to fungicide CON stress, and ii) to examine the effects of NO and fungicide CON treatments on oxidative damage, antioxidant system, secondary metabolism and detoxification of systemic fungicide in wheat seedlings. The results showed that CON fungicide at the highest (4X) concentration significantly decreased wheat seedlings fresh weight (46.89%), shoot length (40.26%), root length (56.11%) and total chlorophyll contents (67.44%) in a dose response relationship. Moreover, CON significantly increased hydrogen peroxide, malondialdehyde, catalase, ascorbate peroxidase, glutathione-S-transferase, and peroxidase activities while decreased reduced glutathione (GSH) content. This ultimately impaired the redox homeostasis of cells, leading to oxidative damage in cell membrane. Under fungicide treatment, the addition of NO reduced the fungicide phytotoxicity, with an increase of over 60% in seedling growth. The NO application mitigated CON phytotoxicity as reflected by significantly increased chlorophyll pigments (69.88%) and decreased oxidative damage in wheat leaves. Indeed, the NO alleviatory effect was able to increase the tolerance of seedlings to fungicide, which resulted increments in antioxidant and detoxification enzymes activity, with the enhanced GSH level (78.54%). Interestingly, NO alleviated CON phytotoxicity through the phenylpropanoid pathway by enhancing the activity of secondary metabolism enzymes such as phenylalanine ammonia-lyase (47.28%), polyphenol oxidase (9%), and associated metabolites such as phenolic acids (77.62%), flavonoids (34.33%) in wheat leaves. Our study has provided evidence that NO plays a key role in the metabolism and detoxification of systemic fungicide in wheat through enhanced activity of antioxidants, detoxifications and secondary metabolic enzymes.

Enhancing spinach (Spinacia oleracea L.) resilience in pesticide-contaminated soil: Role of pesticide-tolerant Ciceribacter azotifigens and Serratia marcescens in root architecture, leaf gas exchange attributes and antioxidant response restoration

This study unveils the detoxification potential of insecticide-tolerant plant beneficial bacteria (PBB), i.e., Ciceribacter azotifigens SF1 and Serratia marcescens SRB1, in spinach treated with fipronil (FIP), profenofos (PF) and chlorantraniliprole (CLP) insecticides. Increasing insecticide doses (25-400 μg kg-1 soil) significantly curtailed germination attributes and growth of spinach cultivated at both bench-scale and in greenhouse experiments. Profenofos at 400 μg kg-1 exhibited maximum inhibitory effects and reduced germination by 55%; root and shoot length by 78% and 81%, respectively; dry matter accumulation in roots and shoots by 79% and 62%, respectively; leaf number by 87% and leaf area by 56%. Insecticide application caused morphological distortion in root tips/surfaces, increased levels of oxidative stress, and cell death in spinach. Application of insecticide-tolerant SF1 and SRB1 strains relieved insecticide pressure resulting in overall improvement in growth and physiology of spinach grown under insecticide stress. Ciceribacter azotifigens improved germination rate (10%); root biomass (53%); shoot biomass (25%); leaf area (10%); Chl-a (45%), Chl-b (36%) and carotenoid (48%) contents of spinach at 25 μg CLP kg-1 soil. PBB inoculation reinvigorated the stressed spinach and modulated the synthesis of phytochemicals, proline, malondialdehyde (MDA), superoxide anions (O2•-), and hydrogen peroxide (H2O2). Scanning electron microscopy (SEM) revealed recovery in root tip morphology and stomatal openings on abaxial leaf surfaces of PBB-inoculated spinach grown with insecticides. Ciceribacter azotifigens inoculation significantly increased intrinsic water use efficiency, transpiration rate, vapor pressure deficit, intracellular CO2 concentration, photosynthetic rate, and stomatal conductance in spinach exposed to 25 μg FIP kg-1. Also, C. azotifigens and S. marcescens modulated the antioxidant defense systems of insecticide-treated spinach. Bacterial strains were strongly colonized to root surfaces of insecticide-stressed spinach seedlings as revealed under SEM. The identification of insecticide-tolerant PBBs such as C. azotifigens and S. marcescens hold the potential for alleviating abiotic stress to spinach, thereby fostering enhanced and safe production within polluted agroecosystems.

From growth inhibition to ultrastructural changes: Toxicological assessment of lambda cyhalothrin and fosetyl aluminium against Bacillus subtilis and Pseudomonas aeruginosa

In modern agricultural practices, agrochemicals and pesticides play an important role in protecting the crops from pests and elevating agricultural productivity. This strategic utilization is essential to meet global food demand due to the relentless growth of the world's population. However, the indiscriminate application of these substances may result in environmental hazards and directly affect the soil microorganisms and crop production. Considering this, an in vitro study was carried out to evaluate the pesticides' effects i.e. lambda cyhalothrin (insecticide) and fosetyl aluminum (fungicide) at lower, recommended, and higher doses on growth behavior, enzymatic profile, total soluble protein production, and lipid peroxidation of bacterial specimens (Pseudomonas aeruginosa and Bacillus subtilis). The experimental findings demonstrated a concentration-dependent decrease in growth of both tested bacteria, when exposed to fosetyl aluminium concentrations exceeding the recommended dose. This decline was statistically significant (p < 0.000). However, lambda cyhalothrin at three times of recommended dose induces 10% increase in growth of Pseudomonas aeruginosa (P. aeruginosa) and 76.8% decrease in growth of Bacillus subtilis (B. subtilis) respectively as compared to control. These results showed the stimulatory effect of lambda cyhalothrin on P. aeruginosa and inhibitory effect on B. subtilis. Pesticides induced notable alterations in biomarker enzymatic assays and other parameters related to oxidative stress among bacterial strains, resulting in increased oxidative stress and membrane permeability. Generally, the maximum toxicity of both (P. aeruginosa and B. subtilis) was shown by fosetyl aluminium, at three times of recommended dose. Fosetyl aluminium induced morphological changes like cellular cracking, reduced viability, aberrant margins and more damage in both bacterial strains as compared to lambda cyhalothrin when observed under scanning electron microscope (SEM). Conclusively the, present study provide an insights into a mechanistic approach of pyrethroid insecticide and phosphonite fungicide induced cellular toxicity towards bacteria.

Ecotoxicological effects of tungsten on celery (Apium graveolens L) and pepper (Capsicum spp.)

Background

Tungsten (W) is an emerging heavy metal pollutant, yet research remains scarce on the biomonitor and sensitive biomarkers for W contamination.

Methods

In this study, celery and pepper were chosen as study subjects and subjected to exposure cultivation in solutions with five different levels of W. The physiological and biochemical toxicities of W on these two plants were systematically analyzed. The feasibility of utilizing celery and pepper as biomonitor organisms for W contamination was explored and indicative biomarkers were screened.

Results

The results indicated that W could inhibit plants' root length, shoot height, and fresh weight while concurrently promoting membrane lipid peroxidation. Additionally, W enhanced the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and total antioxidant capacity (TAOC) to counteract oxidative damage. From a physiological perspective, pepper exhibited potential as a biomonitor for W contamination. Biochemical indicators suggested that SOD could serve as a sensitive biomarker for W in celery, while TAOC and POD were more suitable for the roots and leaves of pepper. In conclusion, our study investigated the toxic effects of W on celery and pepper, contributing to the understanding of W's environmental toxicity. Furthermore, it provided insights for selecting biomonitor organisms and sensitive biomarkers for W contamination.