Encapsulation of oligogalacturonides in chitosan-based nanocarriers enhances elicitor-induced plant immunity and disease resistance

Plant defense elicitors offer an environmentally friendly alternative to conventional crop protection strategies. Oligogalacturonides are pectin-derived damage-associated molecular patterns that activate plant defense responses and represent promising tools for sustainable crop protection. Despite their potential for crop protection, the practical use of oligogalacturonides remains limited by poor stability, low persistence, and suboptimal delivery to plant tissues. In this study, biodegradable chitosan-based nanoparticles were developed as carriers for the oligogalacturonides delivery. Optimization of the chitosan:oligogalacturonide ratio yielded a nanoparticle formulation combining high oligogalacturonide encapsulation efficiency with favourable physicochemical properties. In vitro assay revealed pH-dependent oligogalacturonide recovery, with greater recovery under mildly acidic conditions and a time-dependent enrichment of biologically relevant intermediate-chain oligomers. Biological assays in Arabidopsis thaliana demonstrated that oligogalacturonides encapsulation enhanced multiple defense responses, including defense-related gene expression, callose accumulation, and hydrogen peroxide production. Furthermore, chitosan-based oligogalacturonide nanoparticles pretreatment strengthened defense responses following Botrytis cinerea infection and significantly reduced disease symptoms. These findings highlight the potential of chitosan-based nanocarriers to enhance oligogalacturonides elicitor efficacy and improve protection against fungal pathogens, supporting their application in sustainable plant protection.