Oxidative stress as DNA damage in different transgenic tobacco plants.

Abstract One of the important mechanisms by which plant cells are damaged during adverse environmental conditions is the excessive production of reactive oxygen species (ROS). Major enzymatic ROS scavenging mechanisms of plants include superoxide dismutase (SOD) and catalase (CAT). The aim of this work was to assess leaf cell sensitivity to oxidative stress by measuring DNA damage (Comet assay) in Nicotiana tabacum wild type plants and transgenic lines with deregulated levels of CAT and MnSOD; DNA migration, as DNA damage measure, and nuclei with completely disintegrated head region (hedgehogs), as toxicity parameter, were recorded. A general time dependent increase of DNA migration values was observed within 3 h after hydrogen peroxide treatment, followed by an increase of hedgehog percentage. We showed that hydrogen peroxide treatments trigger different degrees of both DNA migration and hedgehog induction in the transgenic lines. There was only weak difference between the transgenic lines with increased MnSOD levels and wild type plants; but within CATand MnSOD deficient plants, both levels of DNA migration and hedgehogs were significantly altered.