DETOXIFICANT ENZYMES IN PUMPKIN GROWN IN POLLUTED AMBIENT AIR

Pumpkin [Cucurbita pepo (L.) cv. Ambassador] plants were grown under e ither nonfiltered or filtered ambient air in open-top held chambers (O TCs) near the urban area of Milan, Northern Italy. The effects of ambi ent air pollution on the enzymatic detoxification system of the leaves , both in terms of activity and isoform pattern were investigated. The data on air quality showed that ozone was the main phytotoxic polluta nt present in ambient air, reaching a 7 h mean of 63 nL L(-1) and a ma ximum hourly peak of 104 nL L(-1). The peroxidase and catalase activit ies increased fourfold and twofold, respectively in the nonfiltered ai r plants in comparison to the filtered air ones. The peroxidase patter ns were very modified in the polluted plants. In contrast no significa nt changes were found in the activity and isoenzyme pattern of superox ide dismutase. The data reported here suggest that in held-grown pumpk in plants exposed to ambient levels of photooxidants, a stimulation of the peroxidase-catalase detoxification system takes place.