Modulation of aluminum-induced genotoxicity and oxidative stress in Allium cepa L. by Ramalina pollinaria (Westr.) Ach. extract

Aluminum toxicity leads to oxidative stress and genetic instability in organisms, impairing growth and cellular function. This study investigated the protective potential of an aqueous extract obtained from the lichen species Ramalina pollinaria against aluminum-induced toxicity in Allium cepa, a widely used biological indicator in environmental monitoring. Onion bulbs were treated with aluminum chloride (50 mg L^-1), two concentrations (0.5 g L^-1 and 1.0 g L^-1) of lichen extract and lichen extracts together with aluminum chloride. Physiological, cytogenetic, biochemical, and anatomical responses were evaluated following exposure. Aluminum exposure significantly reduced germination, root elongation, and weight gain, while increasing lipid peroxidation, proline accumulation, antioxidant enzyme activities, chromosomal abnormalities, and DNA fragmentation. Co-application of the lichen extract alleviated these effects in a dose-dependent manner. Higher concentrations of the extract led to greater improvements in growth, restoration of mitotic activity, stabilization of chlorophyll levels, and reduction in cellular and genetic damage. Cross-sectional analysis of root meristems confirmed a reduction in tissue injury when the extract was administered. Chemical analysis of the extract revealed a phenolic-rich composition, with compounds likely contributing to its antioxidant and protective efficacy. The findings suggest that R. pollinaria extract may mitigate aluminum toxicity in plants and could have potential applications in environmental protection and phytoremediation, although further studies are required.