HYDROPEROXIDES IN PLANTS EXPOSED TO OZONE MEDIATE AIR-POLLUTION DAMAGE TO ALKENE EMITTERS

OZONE is phytotoxic: it is damaging to cell integrity and photosynthesis1,2, causing leaf necrosis3 and reducing crop yield4. It has been implicated in forest decline5, perhaps through interactions with stress ethene6. Here we show that organic hydroperoxides (ROOH), which are products of ozone-alkene reactions 7-9, are present in the leaves of isoprene-emitting plants after exposure to ozone, but are not found in control plants grown in clean air. On the basis of earlier studies6,7,10, we suggest that this reaction of ozone with biogenic alkenes to produce toxic ROOH could be one of the mechanisms by which damage to plants occurs. This could be particularly important in areas experiencing acidic deposition, where the stability of ROOH will be enhanced. This model may explain in part the die-back of tree species producing reactive alkenes, such as the red spruce, which emits isoprene11-15 and monoterpenes16, and the Norway spruce and silver fir, which are both prolific monoterpene emitters17. © 1990 Nature Publishing Group.