Copper can be found in two oxidation states in plants (Yruela, 2005).
The redox cycle between Cu2+ and Cu+,which is regulated through the
Fenton's reaction, catalyzes the production of hydroxyl radicals (OH−)
derived fromsuperoxide radicals (O2
−) and hydrogen peroxide (H2O2),
thus increasing the production of reactive oxygen species (ROS) (Briat
and Lebrun, 1999)