Durum wheat under plastic pressure: genotype-specific adaptation to polystyrene nanoplastics

An emerging and underestimated threat to crop productivity and food safety stems from the increasing presence of nanoplastics, particularly polystyrene nanoplastics (PSNPs), in agricultural soils, a challenge further intensified by climate change. Although the phytotoxicity of NPs has been examined in several crop species, their impact on Triticum turgidum ssp. durum, a crop of significant nutritional importance and widespread in the semi-arid region, remains largely unexplored. In this study, we assessed the systemic effects of PSNP exposure (10 mg/L) on two durum wheat genotypes, Kronos (wild type) and MRP3 (a low-phytate mutant with altered root traits and micronutrient uptake), following plant development from seedling to grain filling. Through a combined phenotypic, physiological, ionomic, and transcriptomic approach, we identified clear genotype-dependent responses to PSNP-induced stress. Kronos showed a higher tolerance, maintaining nutrient homeostasis and sustaining photosynthetic activity, accompanied by a moderate transcriptional adjustment. In contrast, MRP3 exhibited substantial disruptions in ion balance, alongside intensified oxidative stress and extensive transcriptomic remodeling. Enrichment analyses revealed distinct molecular pathways underpinning each genotype's response, with Kronos activating photosynthesis- and defense-related pathways, while MRP3 triggered responses associated with nutrient deprivation, detoxification, and cell wall biosynthesis. Our findings demonstrate that PSNPs act as a significant abiotic stressor in durum wheat, eliciting genotype-dependent adaptive capacities. The contrasting responses highlight the critical role of transporter-mediated detoxification and nutrient homeostasis in shaping plant resilience to nanoplastic exposure. This study provides the first integrated molecular framework describing PSNP-induced stress responses in durum wheat and underscores the importance of genetic background in determining plant adaptive strategies to emerging environmental contaminants.