EXOGENOUS H2O2 PARTIALLY PREVENTS THE PARAQUAT INDUCED OXIDATIVE STRESS IN THYLAKOID MEMBRANES

In this work we probe the hypothetically protective role of hydrogen peroxide for paraquat induced oxidative damage of thylakoid membranes by means of 77 K fluorescence. We compare the emission and excitation spectra of pea thylakoid membranes isolated after 5 h pretreatment with 2.5 mM hydrogen peroxide or 0.2 mM paraquat and their combination. Paraquat exposure influenced the energy distribution between the two photosystems and reduced their absorption cross section. Hydrogen peroxide pretreatment partially alleviated these effects, thus the potential role of hydrogen peroxide being revealed as a protector against herbicide damages on the level of thylakoid membranes.