Abstract
The effect of chilling temperatures combined with elevated light (5 °C, PPFD 360 δmol m−2 sec−1) on the activity of six antioxidant enzymes and on glutathione peroxidase (GPx) protein accumulation were studied in tobacco Nicotiana tabacum c.v. Petit Havana SRl. At these conditions, transient wilting but no photooxidative damage was observed. As a control, only elevated light treatment was applied (25 °C, PPFD 360 δmol m−2 sec−1). Catalase (EC 1.11.1.6) showed the most dramatic reduction (five-fold) in activity after 4 days of chilling. Dehydroascorbate reductase (DHAR, EC 1.8.5.1) showed 30% reduction in activity while Superoxide dismutase (SOD, EC 1.15.1.1) , ascorbate peroxidase (APx, EC 1.11.1.11), glutathione reductase (GR, EC 1.6.4.2), and monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) were not affected by the chilling treatment. These results indicate that catalase and DHAR are affected by the chilling treatment.
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