Effects of Cytokinins and Antioxidants on the Susceptibility of Membranes to Ozone Damage

Treatment of microsomal membranes isolated from bean cotyledons with ozone induces a lateral phase separation of lipids into discrete liquid-crystalline and gel phase domains. This effect is accompanied by production of malondialdehyde and extensive dismantling of the membranes. All of these deleterious effects of ozone were attenuated by the addition of cytokinins (benzyladenine or zeatin) or antioxidants (sodium benzoate or propyl gallate) to the reaction mixture. The results support previous proposals that the toxic effects of ozone are mediated by the products of its breakdown in water, and that cytokinins may act as radical scavengers to protect plant tissue against the effects of ozone or senescence.