Effect of flooding on the activities of some enzymes of activated oxygen metabolism, the levels of antioxidants, and lipid peroxidation in senescing tobacco leaves

Abstract

Effects of flooding on the activities of some enzymes of activated oxygen metabolism, the levels of antioxidants, and lipid peroxidation in senescing leaves of tobacco were investigated . As judged by the decrease in chlorophyll and protein levels, flooding accelerated the senescence of tobacco leaves . Total peroxide and the lipid peroxidation product, malondialdehyde, increased in both control and flooding-treated leaves with increasing duration of the experiment . Throughout the duration of the experiment, flooded leaves had higher levels of total peroxide and malondialdehyde than did control leaves . Flooding resulted in an increase in peroxidase and ascorbate peroxidase activities and a reduction of superoxide dismutase activity in the senescing leaves . Glycolate oxidase, catalase, and glutathione reductase activities were not affected by flooding . Flooding increased the levels of total ascorbate and dehydroascorbate . Total glutathione, reduced form glutathione, or oxidized glutathione levels in flooded leaves were lower than in control leaves during the first two days of the experiment, but were higher than in control leaves at the later stage of the experiment . Our work suggests that senescence of tobacco induced by flooding may be a consequence of lipid peroxidation possibly controlled by superoxide dismutase activity . Our results also suggest that increased rates of hydrogen peroxide in leaves of flooded plants could lead to increased capacities of the scavenging system of hydrogen peroxide .Abbreviations : GSH = reduced form glutathione ; GSSG = oxidized form glutathione ; GSSG reductase = glutathione reductase ; MDA = malondialdehyde; SOD = superoxide dismutase . 37

Comparative growth and physiological responses of tetraploid and hexaploid species of wheat to flooding stress

“…In a study, barley plants exposed to the flooding for 3 days showed a remarkable decrease in photosynthesis and dry matter accumulation (Yordanova and Popova, 2001). Flooding can generally accelerate leaf senescence due to the chlorophyll degradation by a peroxidase-mediated mechanism (Hurng and Kao, 1994).…”

Different Physiological Reactions at Vegetative and Generative Stage of Development of Field Bean Plants Exposed to Flooding and Undergoing Recovery

“…Root flooding causes a systemic reaction aimed at releasing a defensive reaction in plants, including the activation of antioxidative enzymes. ROS generation is also accompanied by leaf senescence, which also occurs during flooding (Hurng and Kao ). In turn, during recovery period, when plants are re‐exposed to the air and oxygen, oxidative stress is induced again.…”

“…Brownish colour of leaves indicates H 2 O 2 accumulation, but the lack of brown spots may be a consequence of enhanced activity of H 2 O 2 ‐scavenging enzymes such as CAT and peroxidases. Hurng and Kao () stated that increased rates of hydrogen peroxide in leaves of flooded tobacco plants could lead to increased capacities of the system scavenging the hydrogen peroxide. They suppose that accumulation of H 2 O 2 in flooded tobacco leaves is regulated by catalase and glycolate oxidase.…”

Hydrogen peroxide is necessary for abscisic acid-induced senescence of rice leaves

“…The enzyme assays in detail have been described previously (Hurng and Kao, 1994). CAT activity was assayed by measuring the initial rate of disappearance of H 2 O 2 (Kato and Shimizu, 1987).…”