Genetic and DNA-methylation changes induced by potassium dichromate in Brassica napus L.

This study evaluated genetic and DNA methylation alteration induced by potassium dichromate in Brassica napus L.plants. Amplified fragment length polymorphism (AFLP) and selective amplification of polymorphic loci (SAMPL)tests revealed dose-related increases in sequence alterations in plantlets exposed to 10–200 mg/l potassium dichromate.Individual plantlets exposed to chromium under similar conditions showed different AFLP and SAMPL DNA profiles.These observations suggest random DNA mutation in response to potassium dichromate and argue against preferentialsites for mutation. DNA methylation changes in response to chromium treatment were also evaluated. Two complementaryapproaches were applied: (i) immunolabelling, using a monoclonal antibody against 5-methylcytosine; and (ii)methylation-sensitive amplified polymorphism (MSAP). Immunolabelling showed cytosine-hypermethylation in theBrassica napus L. genome when plants were treated with potassium dichromate. MSAP analysis showed extensivemethylation changes in CCGG-sequences, with the net result being genome-wide hypermethylation. These resultsshowed a clear DNA alteration in plants as a response to chromium exposure and the effect was dose-dependent. DNApolymorphism detected by different markers supports the effectiveness of the use of these tools for the investigation ofenvironmental toxicology and for evaluating the concentration of pollutants by DNA analysis in plants.