“…The same tendency was found for SOD, CAT and POD activities in leaves of Hydrocharis dubia in response to 0.5, 1, 2, 3, 4 mM Ni treatments for 3 days (Papadopoulos 2007). Ni has also been shown to increase the plasma membrane (PM) NADPH oxidase, which was shown to be involved in Niinduced ROS generation in roots of 5-day-old wheat seedlings (Triticum durum) (Hao et al 2006). ROS have been shown to damage cell membrane, proteins, lipids and DNA (causing, inter alia, DNA base oxidation, DNA protein cross-links, DNA gaps and breaks), resulting in lipid peroxidation (Boominathan and Doran 2002;Baccouch et al 2001), developmental defects and genetic instability in plant species (Oller et al 1997;Bal and Kasprzak 2002;Papazoglou et al 2005).…”