Cadmium- and copper-induced DNA damage in Pisum sativum roots and leaves as determined by the Comet assay

Alkaline single-cell gel electrophoresis (Comet assay) enables sensitive detection of DNA damage in eukaryotic cells induced by genotoxic agents. The present work aims to study the genotoxic effects of cadmium or copper in pea (Pisum sativum L.) roots and leaves. We performed the Comet assay on cells exposed to cadmium chloride (0.35 mg kg(-1), 0.7 mg kg(-1), 1.4 mg kg(-1), 7.0 mg kg(-1)) or copper chloride (35 mg kg(-1), 70 mg kg(-1), 140 mg kg(-1), 700 mg kg(-1)) for 30 days. The tail moment in migrated DNA was regarded as an indication of DNA damage. The genotoxic test revealed a pronounced DNA alteration in roots of plants exposed to cadmium, and less in those exposed to copper. However, DNA damage in leaves was only significant in plants treated with the higher cadmium concentrations. Analysis of cadmium accumulation showed that roots accumulated almost 50-fold more cadmium than above-ground parts of the plant. This may explain the low genotoxic effects observed in leaves of cadmium-treated plants.