Apoplastic Barrier Remodelling Is Associated With Genotype-Dependent Microplastic Accumulation in Tomato Roots

Microplastics (MPs) pollution has become an emerging environmental issue in agricultural soils, raising concerns about its accumulation in crops and potential transfer through the food chain. However, the mechanisms by which crop genotypes associated MPs uptake and accumulation remain largely unclear. Most previous studies have focused on single cultivars, overlooking intraspecific variability in MPs accumulation. Here, two tomato cultivars, 'AC' (high-accumulation) and 'M82' (low-accumulation), were used to investigate the uptake and accumulation of polystyrene (PS). After 14 days of exposure, the two cultivars showed similar biomass. However, 'AC' accumulated more PS in roots than 'M82' (≈ 19%), as quantified by Eu content (mg/kg, representing the amount of Eu-PS tracer labelling and indicating PS content), indicating genotype-dependent accumulation capacity. Spatial imaging revealed no significant cultivar difference in MPs uptake in the undifferentiated root tip; slight divergence appeared from the meristematic-to-elongation transition zone onward, whereas significant differences were observed in the maturation zone. Multi-omics analyses indicated that 'M82' exhibited enhanced accumulation of cellulose, hemicellulose, pectin, and lignin, which were associated with apoplastic barrier remodelling in the maturation zone and may be related to its lower PS accumulation. Collectively, these findings suggest that genotype-dependent apoplastic barrier traits are correlated with differential MPs accumulation in tomato roots, highlighting potential traits for future efforts to develop crop genotypes with reduced MPs uptake.