Uranium exposure induced reactive oxygen species and nitric oxide generation in Arabidopsis thaliana

The objective of this work was to look at the role of reactive oxygen species (ROS) and nitric oxide (NO) in the uranium induced stress response. Exposing Arabidopsis thaliana roots to uranium, resulted in a significant induction of cell death. Considering the ability of NO to form complexes with metals and alleviation of heavy metal toxicity, we examined the induction of NO following exposure to uranium. Arabidopsis roots and leaves exposed to uranium showed an increase in nitrite concentration indicating the generation of NO. We further confirmed NO production in the roots by DAF-2DA staining in the presence and absence of NO scavenger (methylene blue) and NO synthase inhibitor (L-NAME). DAF fluorescence was weakened in the presence of methylene blue and L-NAME. In addition to NO, the production of hydrogen peroxide in uranium exposed roots was indicated by an increase in DCF fluorescence and measurement as H2O2:TiCl4 complex as well. To further examine the induction of ROS by uranium, the expressions of different genes (LOX and RBOH ) involved in ROS generation in Arabidopsis thaliana are being followed. Our observations suggest that uranium induced ROS and NO generation possibly leading to observed root cell death.