Aluminium-induced DNA damage and adaptive response to genotoxic stress in plant cells are mediated through reactive oxygen intermediates

• Published in: Mutagenesis 2010-03, Vol.25 (2), p.201-209
• Main Authors: Murali Achary, V. Mohan, Panda, Brahma B.
• Format: Article
• Language: English
• Subjects: 1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt - pharmacology; Adaptations; Allium cepa; Aluminum; Aluminum Compounds - toxicity; Astringents - toxicity; Biological and medical sciences; Cell death; Cell Death - drug effects; Chlorides - toxicity; Chromosome Aberrations; Comet Assay; DNA damage; DNA Damage - drug effects; Ethyl methanesulfonate; Ethyl Methanesulfonate - toxicity; Free Radical Scavengers - pharmacology; Fundamental and applied biological sciences. Psychology; genomics; Genotoxicity; Hydrogen peroxide; Hydrogen Peroxide - metabolism; Indicators and Reagents - pharmacology; Manganese; Mercuric chloride; Methylmercury Compounds - toxicity; Molecular and cellular biology; Molecular genetics; Mutagenesis; Mutagenesis. Repair; Mutagens - toxicity; Onions - drug effects; Onions - growth & development; Oxidative Stress - drug effects; Plant cells; Plant Roots - drug effects; Plant Roots - growth & development; Reactive oxygen species; Reactive Oxygen Species - metabolism; Roots; Spindles; Superoxides - metabolism; Thiourea - analogs & derivatives; Thiourea - pharmacology
• ISSN: 0267-8357; 1464-3804
• DOI: 10.1093/mutage/gep063

Experiments employing growing root cells of Allium cepa were conducted with a view to elucidate the role of reactive oxygen intermediates (ROI) in aluminium (Al)-induced DNA damage, cell death and adaptive response to genotoxic challenge imposed by ethyl methanesulphonate (EMS) or methyl mercuric chloride (MMCl). In a first set of experiments, root cells in planta were treated with Al at high concentrations (200–800 μM) for 3 h without or with pre-treatments of dihydroxybenzene disulphonic acid (Tiron) and dimethylthiourea (DMTU) for 2 h that trap O2·−and hydrogen peroxide (H2O2), respectively. At the end of treatments, generation of O2·− and H2O2, cell death and DNA damage were determined. In a second set of experiments, root cells in planta were conditioned by Al at low concentrations (5 or 10 μM) for 2 h and after a 2 h intertreatment interval challenged by MMCl or EMS for 3 h without or with a pre-treatment of Tiron or DMTU. Conditioning treatments, in addition, included two oxidative agents viz rose bengal and H2O2 for comparison. Following treatments, root cells in planta were allowed to recover in tap water. Genotoxicity and DNA damage were evaluated by micronucleus (MN), chromosome aberration (CA) or spindle aberration (SA) and comet assays at different hours (0–30 h) of recovery. The results demonstrated that whereas Al at high concentrations induced DNA damage and cell death, in low concentrations induced adaptive response conferring genomic protection from genotoxic challenge imposed by MMCl, EMS and Al. Pre-treatments of Tiron and DMTU prevented Al-induced DNA damage, cell death, as well as genotoxic adaptation to MMCl and EMS, significantly. The findings underscored the biphasic (hormetic) mode of action of Al that at high doses induced DNA damage and at low non-toxic doses conferred genomic protection, both of which were mediated through ROI but perhaps involving different networks.