Soil erosion is a major drive for nano & micro-plastics to enter riverine systems from cultivated land.

Nano and micro-plastics (NMPs, particles diameter <5 mm), as emerging contaminants, have become a major concern in the aquatic environment because of their adverse consequences to aquatic life and potentially human health. Implementing mitigation strategies requires quantifying NMPs mass emissions and understanding their sources and transport pathways from land to riverine systems. Herein, to access NMPs mass input from agricultural soil to riverine system via water-driven soil erosion, we have collected soil samples from 120 cultivated land in nine drainage basins across China in 2021 and quantified the residues of six common types of plastic, including polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), polypropylene (PP), polyethylene (PE), polycarbonate (PC), and polystyrene (PS). NMPs (Σ6plastics) were detected in all samples at concentrations between 3.6 and 816.6 µg/g dry weight (median, 63.3 µg/g) by thermal desorption/pyrolysis-gas chromatography-mass spectrometry. Then, based on the Revised Universal Soil Loss Equation model, we estimated that about 22,700 tonnes of NMPs may enter the Chinese riverine system in 2020 due to agricultural water-driven soil erosion, which occurs primarily from May to September. Our result suggested that over 90% of the riverine NMPs related to agricultural soil erosion in China are attributed to 36.5% of the country's total cultivated land, mainly distributed in the Yangtze River Basin, Southwest Basin, and Pearl River Basin. The migration of NMPs due to water-driven soil erosion cannot be ignored, and erosion management strategies may contribute to alleviating plastic pollution issues in aquatic systems.

The phosphorylation of the movement protein TGBp1 regulates the accumulation of the Bamboo mosaic virus.

Phosphorylation and dephosphorylation of viral movement proteins plays a crucial role in regulating virus movement. Our study focused on investigating the movement protein TGBp1 of Bamboo mosaic virus (BaMV), which is a single-stranded positive-sense RNA virus. Specifically, we examined four potential phosphorylation sites (S15, S18, T58, and S247) within the TGBp1 protein. To study the impact of phosphorylation, we introduced amino acid substitutions at the selected sites. Alanine substitutions were used to prevent phosphorylation, while aspartate substitutions were employed to mimic phosphorylation. Our findings suggest that mimicking phosphorylation at S15, S18 and T58 of TGBp1 might be linked to silencing suppressor activities. The phosphorylated form at these sites exhibits a loss of silencing suppressor activity, leading to reduced viral accumulation in the inoculated leaves. Furthermore, mimicking phosphorylation at residues S15 and S18 could diminish viral accumulation at the single-cell level, while doing so at residue T58 could influence virus movement. However, mimicking phosphorylation at residue S247 does not appear to be relevant to both functions of TGBp1. Overall, our study provides insights into the functional significance of specific phosphorylation sites in BaMV TGBp1, illuminating the regulatory mechanisms involved in virus movement and silencing suppression.

Depth distribution of nano- and microplastics and their contribution to carbon storage in Chinese agricultural soils.

The extensive and prolonged utilization of plastic materials in agriculture has primarily led to the accumulation of nano- and microplastics (NMPs, ≤5 mm) in farmland soils. The spatial-vertical distribution of NMPs mass concentrations and their impact on the national agricultural soil carbon reservoir remain unexamined. In this study, we quantified the residual mass concentrations of six prevalent plastic types in farmland soils around China using the double-shot model of thermal desorption/pyrolysis-gas chromatography-mass spectrometry (TD/Py-GC-MS). The results showed that median NMPs concentrations were 79.81 µg/g in the topsoil layer (0-15 cm), 57.17 µg/g in the middle soil layer (15-30 cm), and 32.90 µg/g in the bottom soil layer (30-45 cm). Overall, agricultural soil NMPs levels declined from the surface to deeper soil layers; however, some regions exhibit an opposite trend. Furthermore, our estimations indicate that carbon sourced from NMPs contributes to the agricultural soil carbon pool within a range from 0.004 % to 5.606 %, depending on the soil depth. As a hallmark of sustainable agricultural soil management, it is noteworthy that the concealed and continuously expanding carbon contribution of NMPs has an impact on soil carbon storage, albeit at a relatively low level. Our data serves as a foundational reference point and enables a precise evaluation of future contributions of NMPs to the storage of carbon in agricultural soils within China.