Arsenic (As) contamination in soil represents a major challenge to global agriculture, threatening crop productivity and food security, making the development of effective mitigation strategies essential for sustainable farming. Synthetic bacterial communities (SynCom) improve host plants ability to withstand As stress by several mechanisms. It is well known that polyamines (PAs) strengthen the antioxidant defence system, prevent ethylene formation, preserve cell pH, and shield plant cells from the damaging effects of As, and so forth; nevertheless, it is still unknown how SynCom modify PA metabolism to improve plant resistance to As. Pot experiment was carried out to evaluate how SynCom affects root PA homeostasis, hydrogen peroxide (metabolite associated with PA), genes encoding antioxidant system and expression and activities of PA- associated degrading and synthesizing enzymes in rice subjected to As. SynCom inoculated plants exhibited maximum growth attributes, gene expression of two plasma membrane intrinsic protein, leaf water potential, and chlorophyll contents than non-inoculated plants exposed to As stress. With increased activity of PA catabolic enzymes (copper-containing diamine oxidase, CuAO; polyamine oxidase, PAO) and putrescine synthases (ornithine decarboxylase; arginine decarboxylase, ADC), SynCom inoculated plants resulted in higher putrescine and cadaverine concentrations but lower spermidine and spermine contents. Under As stress, the SynCom inoculated plants resulted in up-regulation of spermine synthase gene, OsSPMS, and down-regulation of PA catabolic enzyme genes (OsCuAO6, OsCuAO8, OsCuAO1 and OsCuAO2) and PA synthase genes (OsADC2 and OsADC1). As stressed plants inoculated with SynCom had higher level of expression in OsPAO1, OsPAO2, OsPAO3 as compared to non-inoculated plants, stimulating reactive oxygen species-associated stress responsiveness signaling through low H2O2 levels by enhancing the genes encoding antioxidant defence system (OsCu/Zn-SOD, OsCAT1 and OsMn-SOD). The results of this study showed that SynCom can alter PA metabolism to improve plants' resistance to heavy metals like As. The inoculation of SynCom emerges as a promising strategy to enhance plant resilience against As toxicity by promoting positive interactions and regulatory stress-responsive pathways. Furthermore, the inoculation of SynCom is a viable approach capable of ameliorating heavy metal stress and improving the productivity of crops in the contaminated soil by fostering positive interactions and stress responsive regulatory mechanisms. (c) 2025 SAAB. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Microplastics (MPs), which are widely dispersed in terrestrial environments, threaten crop growth and human food security. However, plant accumulation and phytotoxicity related to the size effects of MPs remain insufficiently explored. This study investigated the accumulation and toxicity of two sizes of MPs on Capsicum annuum Linn. (C. annuum) through fluorescence tracing and antioxidant defense system assessment. The results revealed that the size of MPs significantly impacts their accumulation characteristics in C. annuum roots, leading to variations in toxic mechanisms, including oxidative stress and damage. Smaller MPs and higher exposure concentrations result in more pronounced growth inhibition. C. annuum roots have a critical size threshold for the absorption of MPs of approximately 1.2 mu m. MPs that enter the root tissue exhibit an aggregated form, with smaller-sized MPs displaying a greater degree of aggregation. MP exposure induces oxidative stress in root tissues, with high concentrations of smaller MPs causing lipid peroxidation. Analysis of the IBR values revealed that C. annuum roots utilize ascorbic acid (ASA) to prevent oxidative damage caused by larger MPs. Conversely, smaller MPs primarily induce superoxide dismutase (SOD) and glutathione (GSH). These results emphasize the significant impact of MP size on plant antioxidant defense response mechanisms, laying the foundation for further investigating the implications for human health.

Key messageBoron is essential for plants, but excess can induce toxicity.AbstractBoron (B) is a vital micronutrient for plants, but excess B can induce toxicity symptoms and reduce crop yields. B bioavailability depends on soil properties, including clay type, pH, and organic matter content. Symptoms of B toxicity include reduced shoot and root growth, leaf chlorosis and necrosis, impaired photosynthesis, and disrupted pollen development. This review paper examines the current knowledge on B toxicity mechanisms, tolerance strategies, and management approaches in plants. This review covers (1) factors affecting B bioavailability; (2) toxicity symptoms in plants; (3) uptake, transport, and detoxification mechanisms; and (4) strategies. To mitigate toxicity, plants reduce B uptake, activate efflux transporters, compartmentalize B, and enhance antioxidant systems. On the basis of this review, future research should focus on identifying novel tolerance mechanisms, exploring genetic strategies for improved B management, and developing innovative agronomic interventions. These insights will facilitate the breeding and management of crops for enhanced productivity under B toxicity stress.

Root-knot nematodes (RKNs) are a vital pest that causes significant yield losses and economic damage to potato plants. The use of chemical pesticides to control these nematodes has led to environmental concerns and the development of resistance in the nematode populations. Endophytic fungi offer an eco-friendly alternative to control these pests and produce secondary metabolites that have nematicidal activity against RKNs. The objective of this study is to assess the efficacy of Aspergillus flavus (ON146363), an entophyte fungus isolated from Trigonella foenum-graecum seeds, against Meloidogyne incognita in filtered culture broth using GC-MS analysis. Among them, various nematicidal secondary metabolites were produced: Gadoleic acid, Oleic acid di-ethanolamide, Oleic acid, and Palmitic acid. In addition, biochemical compounds such as Gallic acid, Catechin, Protocatechuic acid, Esculatin, Vanillic acid, Pyrocatechol, Coumarine, Cinnamic acid, 4, 3-indol butyl acetic acid and Naphthyl acetic acid by HPLC. The fungus was identified through morphological and molecular analysis, including ITS 1-4 regions of ribosomal DNA. In vitro experiments showed that culture filtrate of A. flavus had a variable effect on reducing the number of egg hatchings and larval mortality, with higher concentrations showing greater efficacy than Abamectin. The fungus inhibited the development and multiplication of M. incognita in potato plants, reducing the number of galls and eggs by 90% and 89%, respectively. A. flavus increased the activity of defense-related enzymes Chitinas, Catalyse, and Peroxidase after 15, 45, and 60 days. Leaching of the concentrated culture significantly reduced the second juveniles' stage to 97% /250 g soil and decreased the penetration of nematodes into the roots. A. flavus cultural filtrates via soil spraying improved seedling growth and reduced nematode propagation, resulting in systemic resistance to nematode infection. Therefore, A. flavus can be an effective biological control agent for root-knot nematodes in potato plants. This approach provides a sustainable solution for farmers and minimizes the environmental impact.

Melatonin (MT) and reduced glutathione (GSH) roles in mitigating chromium (Cr) toxicity in sweetpotato were explored. Plants, pre-treated with varying MT and GSH doses, were exposed to Cr (40 mu M). Cr severely hampered growth by disrupting leaf photosynthesis, root system, and oxidative processes and increased Cr absorption. However, the exogenous application of 1 mu M of MT and 2 mM of GSH substantially improved growth parameters by enhancing chlorophyll content, gas exchange (Pn, Tr, Gs, and Ci), and chlorophyll fluorescence (Fv/Fm, ETR, qP, and Y(II)). Furthermore, malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide ion (O-2(center dot-)), electrolyte leakage (EL), and Cr uptake by roots (21.6 and 27.3%) and its translocation to shoots were markedly reduced by MT and GSH application, protecting the cell membrane from oxidative damage of Cr-toxicity. Microscopic analysis demonstrated that MT and GSH maintained chloroplast structure and integrity of mesophyll cells; they also enhanced stomatal length, width, and density, strengthening the photosynthetic system and plant growth and biomass. MT and GSH improved osmo-protectants (proline and soluble sugars), gene expression, and enzymatic and non-enzymatic antioxidant activities, mitigating osmotic stress and strengthening plant defenses under Cr stress. Importantly, the efficiency of GSH pre-treatment in reducing Cr-toxicity surpassed that of MT. The findings indicate that MT and GSH alleviate Cr detrimental effects by enhancing photosynthetic organ stability, component accumulation, and resistance to oxidative stress. This study is a valuable resource for plants confronting Cr stress in contaminated soils, but further field validation and detailed molecular exploration are necessary.