ISHS Acta Horticulturae 579: II Balkan Symposium on Vegetables and Potatoes
CHLOROPHYLL PHOTOOXIDATION AND CHANGES IN THE ANTIOXIDANT PROTECTIVE ENZYMES IN LEAVES OF CAPSICUM ANNUUM AND CUCUMIS SATIVUS SEEDLINGS SUBJECTED TO CHILLING AT HIGH LIGHT INTENSITY |
| Authors: | A.S. Saropulos, D.S.H. Drennan |
| Keywords: | Cucumber, pepper, superoxide dismutase, ascorbate peroxidase, glutathione reductase. |
| Abstract:
The extent of chlorophyll photooxidation and the extractable activities of three active-oxygen scavenging enzymes were examined in the youngest fully expanded leaves of cucumber (Cucumis sativus L.) and pepper (Capsicum annuum L.) seedlings after exposure for two days to 9°C at PPFD = 1550 μmol m-2 s-1 with 12 h photoperiod, followed by a recovery period of another two days at 22°C and PPFD=180 µmol m-2 s-1 with 12 h photoperiod. Pepper leaves were resistant to chlorophyll photodestruction, while cucumber leaves suffered great losses (53% of pre-chilling levels), especially during the recovery period. Photobleached cucumber leaves had a lower chlorophyll a/b ratio than unchilled leaves. Soluble proteins were also decreased in cucumber leaves as a result of the treatment. Unchilled pepper leaves had the highest extractable activity of superoxide dismutase per unit protein or dry weight and there was an increase in ascorbate peroxidase extractable activity per unit protein or dry weight in pepper leaves during the chilling period. The chilling treatment decreased significantly both the superoxide dismutase and the ascorbate peroxidase activities on a dry weight basis in cucumber leaves and further losses of ascorbate peroxidase and glutathione reductase activity per dry weight were observed in the recovery period. | |
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