Novel role of isosorbide as a biostimulant in enhancing plant growth and development in Arabidopsis thaliana

Sustainable agriculture faces growing challenges in boosting food production while minimizing environmental impact, highlighting the need for innovative solutions. The "plastics to fertilizers" concept, which converts poly(isosorbide carbonate) (PIC) derived from plastic waste into urea and isosorbide, presents a promising approach, as we have previously reported (Abe in Green Chem 23:9030-9037, 2021). While urea's role in plant nutrition is well established, the effect of isosorbide on plant growth and development remains largely unexplored. This study evaluates the impact of exogenous isosorbide treatment on Arabidopsis thaliana, aiming to unveil its potential as a biostimulant. Plants were grown in media with varying concentrations (0-10 mM) of isosorbide. Based on the optimal dose, determined by enhancements in shoot biomass and primary root length, we further analysed several parameters, including carbon and nitrogen content, carbon-to-nitrogen (C/N) ratio, nitrogen use efficiency (NUE), ionomic profiles, transcriptomic changes, and stress tolerance. Our results demonstrate that isosorbide treatment significantly promotes plant growth, with a significant increase in shoot biomass, improved C/N ratio, and enhanced NUE. Ionome analysis revealed altered distributions of essential elements in shoots and roots, indicating that isosorbide influence nutrient uptake and allocation. In addition, isosorbide enhanced plant growth under nitrogen deficiency and salt stress conditions. Transcriptomic analysis identified 447 differentially expressed genes in shoots and 327 in the roots, with significant enriched in pathways related to stress adaptation, metabolism, and hormonal regulation. Together, these findings provide novel insights into the biostimulant potential of isosorbide, highlighting its robust impact on plant growth and stress resilience while offering an innovative link between polymer recycling and sustainable agriculture.