DNA damage and repair in Arabidopsis thaliana as measured by the comet assay after treatment with different classes of genotoxins

The three protocols of the comet assay A/N, A/A and N/N were for the first time applied to the plant species Arabidopsis thaliana. The purpose of the experiments was to establish conditions for genotoxic exposure causing DNA damage in Arabidopsis nuclei. This is required for comprehensive gene expre ssion profiling with the intention to screen for genes involved in response of Arabidopsis cells to,genotoxic stress. Five chemicals belonging to different classes of mutagens (the monofunction al alkylating agents N-methyl-N-nitrosourea and methyl methanesulfonate, th e polyfunctional alkylating agent mitomycin C, the radiomimetic bleomycin a nd the herbicide maleic hydrazide) were tested. Except for maleic hydrazide , dose-dependent increases in DNA damage were found using the A/N comet ass ay protocol. While a rapid repair of bleomycin-mediated SSBs and DSBs was f ound, no significant reduction of DNA migration was observed up to 48 h aft er treatment with the monofunctional alkylating agents. (C) 2001 Elsevier S cience B.V. All rights reserved.