Genotoxic endpoints in a Pb-accumulating pea cultivar: insights into Pb contamination limits.

Lead (Pb) persists among the most hazardous contaminant metals. Pb-induced genotoxic effects remain a matter of debate as they are a major cause of plant growth impairment, but assessing Pb genotoxicity requires the selection of Pb-sensitive genotoxic biomarkers. Seedlings of the ecotoxicological model species Pisum sativum L. were exposed to Pb (≤ 2000 mg L). Flow cytometry (FCM) revealed that 28 days after, Pb arrested root cell cycle at G but no eu/aneuploidies were found. Comet assay and FCM-clastogenicity assays showed that Pb increased DNA breaks in roots at concentrations as low as 20 mg L. Leaves showed no variation in DNA-ploidy or cell cycle progression but had increased DNA breaks at the highest Pb dose. We conclude that both Comet assay and the full-peak coefficient of variation (FPCV) were the most relevant endpoints of Pb-phytogenotoxicity. Also, the Pb-induced DNA breaks may be related with the arrest at the G-checkpoint. Data will be relevant to better define Pb ecogenotoxicological effects and their measuring tools and may contribute to a regulatory debate of this pollutant limits.