Allium cepa L. as a bioindicator: A comprehensive review of genotoxicity and cytotoxicity assessment methods

Allium cepa L., commonly known as the bulb onion, is widely cultivated and used globally for its culinary and medicinal purposes. It plays a significant role in genotoxicity and cytotoxicity testing. Onion (Allium cepa L.), a perennial herb from the Amaryllidaceae family, is recognized for its high dietary fiber content. It is a biennial plant with fibrous, adventitious roots, 3–8 distichous, glaucous leaves, and a bulb made up of concentric, enlarged, fleshy leaf bases. The outer leaf bases dry out, becoming thin and varying in color to form a protective layer, while the inner bases thicken as the bulb matures. Allium cepa L. is widely used as a flavoring agent in the food industry and is known for its antimicrobial properties. This review discusses the Allium cepa L. assay (AT) as an effective and economical method for evaluating genotoxic effects through the analysis of chromosomal aberrations and DNA damage. This assay provides an alternative to animal testing and includes various methods for genotoxicity assessment, such as the comet assay and micronucleus assay, as well as techniques for cytotoxicity evaluation like the MTT assay and root growth inhibition assay. It emphasizes the sensitivity of Allium cepa L. to environmental pollutants and heavy metals that disrupt physiological processes. The article also reviews the health benefits of bioactive compounds in onions, such as sulfur compounds, saponins, and fructans, highlighting the importance of Allium cepa L. in environmental monitoring. Additionally, the review examines the impact of fungicides like mancozeb and benodanil on environmental and human health, using Allium cepa L. as a bioindicator to detect chromosomal and mitotic disturbances. This comprehensive review underscores the value of Allium cepa L. in environmental monitoring, its wide range of applications in toxicity assessment and research, as well as its historical and modern uses in medicine. The aim is to compile current evidence on the phytochemistry, genotoxicity, and cytotoxicity of Allium cepa L., emphasizing its role as a standard bioindicator in environmental and toxicological studies. Looking ahead, integrating Allium cepa L. assays with molecular and omics-based approaches could further enhance their utility in modern environmental monitoring and pharmaceutical toxicology.