The cell system that detoxificates organic xenobiotics comprises three stages. Each of them involves a number of enzymes that, depending on the character of the degraded organic compound, lead to its transformations. The enzymes of the first stage – bioactivation – are generally polysubstrate mono- oxygenases, flavine-containing monooxygenases (FMO), and the enzymes showing hydrolytic and oxido- reductive activity. Induction of the enzymes influenced by xenobiotic has been confirmed by the SAGE studies (Serial Analysis of Gene Expression).

All organisms are exposed to reactive oxygen species such as hydrogen peroxide (H2O2), superoxide anion (O2· –) and hydroxyl radical (·OH) as unavoidable products of oxidative metabolism. Many biotic and abiotic factors such as: pathogens, air pollutants, salts, xenobiotic, heavy metals, UV radiation initiate ROS formation. The main sites of ROS formation in plant cells are chloroplasts, peroxisomes and mitochondria. ROS can cause wide-ranging damage to many macromolecules including proteins, lipids and nucleic acids, eventually leading to cell death.

Almost all soils has seen a steady increase in the content of heavy metals, mainly due to anthropogenic activities . The presence of elevated concentrations of metals has a number of adverse changes in the functioning of the plant cell.