Orizalin-induced polyploidy in Capsicum annuum L.: stress-responsive proteins and breeding potential

Artificial polyploidization using β-tubulin depolymerizing agents like oryzalin represents a promising strategy for increasing genetic diversity in plant breeding programs. This study investigates the efficacy of oryzalin in inducing polyploidy in ornamental Capsicum annuum L., focusing on morphological, anatomical, cytogenetic, and molecular changes that support plant survival under toxic stress. Seeds from three genotypes (UFPB-001, UFPB-004, and Floribela) were subjected to varying oryzalin concentrations and exposure durations. While higher concentrations reduced survival rates, no lethal dose was observed, indicating lower phytotoxicity compared to colchicine. Molecular docking simulations revealed interactions between oryzalin and stress-related proteins 5YJS and 1SM4, suggesting the activation of defense mechanisms. Cytogenetic analysis confirmed polyploid induction in three plants, with rates of 25.0%, 33.3%, and 50.0% in UFPB-001, Floribela, and UFPB-004, respectively. Polyploid plants exhibited larger, thicker leaves, altered stomatal density, and increased chloroplasts per guard cell. These findings establish oryzalin as a potent polyploidy inducer, with potential applications in Capsicum breeding programs.