The widespread use of plastic agricultural films necessitates a thorough evaluation of environmental risks posed by soil microplastics (MPs). While the intestinal tract is a critical site for MP interactions in soil organisms, current research predominantly focuses on overall physiological responses, overlooking organ-specific toxic mechanisms. To address this gap, we exposed earthworms (Eisenia fetida) to polyethylene (PE) and biodegradable polylactic acid (PLA) MPs sourced from agricultural films at an environmentally realistic concentration of 1.0 g/kg. Incorporating natural earthworm mobility, we designed two exposure scenarios: migration from clean to contaminated soil (scenario A) and vice versa (scenario B). Machine learning-driven image analysis and phenotypic profiling revealed that PE induced more severe intestinal lesions than PLA, adversely affecting intestinal immune functions. Furthermore, PE resulted in greater oxidative damage and significantly activated immune proteins such as melanin and antimicrobial peptides through reprograming immune-related gene and protein pathways. Conversely, PLA predominantly disrupted intestinal digestive and absorptive functions, though the gut microbial community partially mitigated damage through structural and compositional adaptation. Compared with scenario A, earthworms in scenario B exhibited reduced tissue damage, enhanced digestive enzyme activity, and upregulated energy-related metabolites and cell proliferation genes, indicating partial recovery from MP-induced intestinal dysfunction. These findings elucidate the distinct toxicity mechanisms of conventional and biodegradable agricultural MPs on soil organisms, while the scenario-based approach advances risk assessment by aligning experimental design with real-world ecological behaviors.

Antimony (Sb) poses a significant ecological threat. This study combines biochemical, pathological, transcriptome, and metabolome analyses to assess the short-term (14-day) toxic impact of two Sb levels (25 mg/kg and 125 mg/kg) on earthworms (Eisenia fetida). Higher Sb concentration caused severe intestinal damage, elevated metallothionein (MT) levels, and reduced antioxidant capacity. Metabolome analysis identifies 404 and 1698 significantly differential metabolites in the two groups. Metabolites such as S(-)-cathinone, N-phenyl-1naphthylamine, serotonin, 4-hydroxymandelonitrile, and 5-fluoropentylindole contributed to the metabolic responses to Sb stress. Transcriptome analysis shows increased chitin synthesis as a protective response, impacting amino sugar and nucleotide sugar metabolism for cell wall synthesis and damage repair. Integrated analysis indicated that 5 metabolite-gene pairs were found in two Sb levels and 11 enriched pathways were related to signal transduction, carbohydrate metabolism, immune system, amino acid metabolism, digestive system, and nervous system. Therefore, the integration of multiomics approaches enhanced our comprehension of the molecular mechanisms underlying the toxicity of Sb in E. fetida.

The increasing salinization of soils and resulting degradation of irrigated lands have directly affected 2.6 billion hectares of dryland agriculture worldwide. This phenomenon has led to significant qualitative and quantitative losses in crop production. The absorption and accumulation of ions adversely affect plants by disrupting photosynthetic machinery, damaging tissues, disturbing the ionic balance of cells, and inducing oxidative stress. Rhizobacteria-induced salinity tolerance is a promising tool in crop plants that works by modulating the plant metabolism. Among rhizobacteria, halotolerant plant growth promoting rhizobacteria (PGPR) stand out as particularly significant because they can extend salinity tolerance in crop plants through various mechanisms, including secondary metabolite production, osmolyte accumulation, and modulation of plant metabolism via certain localized and systemic defense functions. Furthermore, the volatile organic compounds produced by PGPR play a vital role in salinity amelioration by regulating root ions uptake, promoting osmolyte related genes expression, reducing the level of oxidative stress markers such as electrolyte leakage, and maintaining endogenous hormonal levels. These novel salt-ameliorating mechanisms and their ability to improve plant fitness and enhance tolerance to salinized soils highlight halotolerant PGPR as eco-friendly and cost-effective tools for salt stress tolerance. This review focuses on elucidating the novel mechanisms used by halotolerant PGPR, their production of secondary metabolites under salinity stress, their application as bioinoculants for crop plants in salinized soils and the development of novel bioformulations for the bioremediation of agricultural soils facing salt stress-related challenges.