OZONE-INDUCED ALTERATIONS IN THYLAKOID PROTEIN-PATTERNS IN PUMPKIN LEAVES OF DIFFERENT AGE

Photosynthetic electron transport activities, two-dimensional electrop horesis and immunoblot analyses were carried out on thylakoid membrane s of ozone-treated pumpkin leaves of different age. Mature symptomatic leaves showed a decline in PSI, PSII and whole chain activities and a reduced PSII protein content. In young asymptomatic leaves the PSII a ctivity remained unchanged and the content of the PSII reaction center Dl protein increased. Our data show that O3-derived toxic molecular s pecies act on photosynthetic performance, inducing alterations on thyl akoid proteins. The different behaviour between young and mature leave s, may be due to the different physiological and metabolic characteris tics of the different aged tissues.