Genotoxic endpoints in a Pb-accumulating pea cultivar: insights into Pb2+ contamination limits.

Abstract

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 Pb2+ (≤ 2000 mg L-1). Flow cytometry (FCM) revealed that 28 days after, Pb2+ arrested root cell cycle at G2 but no eu/aneuploidies were found. Comet assay and FCM-clastogenicity assays showed that Pb2+ increased DNA breaks in roots at concentrations as low as 20 mg L-1. Leaves showed no variation in DNA-ploidy or cell cycle progression but had increased DNA breaks at the highest Pb2+ 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 G2-checkpoint. Data will be relevant to better define Pb2+ ecogenotoxicological effects and their measuring tools and may contribute to a regulatory debate of this pollutant limits.