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Yong In Kuk, Jae Hong Lee, Han Yong Kim, Soon Ju Chung, Gap Chae Chung, Ja Ock Guh, Hee Jae Lee, and Nilda R. Burgos

To determine whether chilling tolerance is related to cold acclimation, changes in physiological responses and activity of antioxidative enzymes were investigated in leaves of cucumber (Cucumis sativus L.) grown in controlled environments. Plants were exposed to 15 °C (cold-acclimated) or 25 °C (nonacclimated) for 3 days, under 50 μmol·m-2·s-1 photosynthetic photon flux and 70% relative humidity. Plants were then exposed to 8 °C chilling temperature for 3 days, and allowed to recover in a growth chamber at 25 °C for 3 days. Measurements of leaf water content, cellular leakage, lipid peroxidation, chlorophyll a fluorescence, and quantum yield showed that cold-acclimated leaves were less affected by chilling compared to nonacclimated leaves. Cold-acclimated leaves recovered faster than nonacclimated leaves with regard to all variables examined. Catalase and ascorbate peroxidase activities were induced in cold-acclimated leaves, but not in nonacclimated leaves. These data indicate that cold acclimation increased chilling tolerance of cucumber in association with antioxidative enzymes.

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Zohar Shaham, Amnon Lers, and Susan Lurie

`Granny Smith' apples [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] were harvested in two seasons and stored at 0 °C air storage with no pretreatment (control), after heating for 4 d at 38 °C, or after treating for 16 hours at 20 °C with 1 μL·L-1 1-methylcyclopropene (1-MCP). The effects of the two treatments on superficial scald development were consistent over both seasons. Scald began to appear after 8 weeks in control fruit, after 16 weeks in heated fruit but not on 1-MCP treated fruit. α-Farnesene accumulation and oxidation were slower in the skin of heated than in control fruit, and almost entirely absent in 1-MCP treated fruit. The activities of five antioxidant enzymes, ascorbate peroxidase, catalase, glutathione reductase, peroxidase and superoxide dismutate, were measured at two-week intervals in the apple peel, quantitatively as total activity and qualitatively by isozyme analysis. Enzyme activities either increased or remained stable during 16 weeks of storage, except for superoxide dismutase activity, which decreased. Ascorbate oxidase activity was higher in heated than control apples and there was an additional peroxidase isozyme present in activity gels. The activities of antioxidant enzymes were lower in 1-MCP treated fruit except for catalase during the first month of storage. Lipid soluble antioxidant activity was higher in 1-MCP treated fruit than the fruit of the other treatments, and water soluble antioxidant activity was higher in both treatments than in control fruit during the time that scald was developing in control apples. Both free and total phenol contents in the peel fluctuated during storage but no consistent trend was detected. The differences in enzyme activity and antioxidant content of the peel of 1-MCP and heated apples may play a role in preventing or delaying the appearance of superficial scald.

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Rumana Yeasmin, Stephen P. Bonser, Satoru Motoki, and Eiji Nishihara

these ROS is one of the major damaging factors in plants ( Wahid et al., 2007 ). To limit oxidative damage under stress conditions, plants have developed a series of detoxification systems involving several antioxidative enzymes, such as superoxide

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Sukhvinder Pal Singh and Zora Singh

antioxidant enzymes. Enzyme extracts of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were prepared and assays were performed as previously described ( Singh et al., 2012 ). SOD assay involved the measurement of cytochrome c (Cyt c

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Safwan Shiyab

to remove the residual solvent and were stored at –20 °C for starch analysis. Determination of antioxidative enzyme activities. Leaf tissues from sour orange seedlings were homogenized separately in a prechilled mortar and pestle under ice

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Huiying Li, Hongji Luo, Deying Li, Tao Hu, and Jinmin Fu

superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), and other antioxidative enzymes were detected in both horse gram ( Macrotyloma uniflorum ) and bengal gram ( Cicer arietinum ) subjected to Pb, and the levels of enzymes were dependent

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Dawei Shi, Xiaodong Wei, Guoxiang Chen, and Yanli Xu

= 1 Jan. The changes in the activities of primary antioxidative enzymes (SOD, APX, CAT, and POD) are shown in Figure 7 . The activities of SOD, CAT, and APX increased, reaching their highest values at Day 266 and then decreasing significantly, which

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Yiwei Jiang, Eric Watkins, Shuwei Liu, Xiaoqing Yu, and Na Luo

studies. Antioxidant enzyme activity and lipid peroxidation. The collected leaf tissue was ground into powder in liquid N. Antioxidative enzymes were then extracted by mixing 0.1 g of leaf tissue power with 1.0 mL of extraction buffer [50 m m

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Jing Tian, Li-Ping Wang, Yan-Juan Yang, Jin Sun, and Shi-Rong Guo

degradation ( Wahid et al., 2007 ). In addition to tissue dehydration, heat stress may induce oxidative stress in plants, which causes lipid peroxidation and subsequent membrane injury, protein degradation, enzyme inactivation, pigment bleaching, and

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Lingyun Yuan, Yujie Yuan, Shan Liu, Jie Wang, Shidong Zhu, Guohu Chen, Jinfeng Hou, and Chenggang Wang

) . Activities of antioxidative enzymes in chloroplasts. Ascorbate peroxidase (APX) activity was measured by Nakano and Asada (1981) with slight modifications. Reaction buffer solution contained 50 m m K-P buffer (pH 7.0), 0.5 m m AsA, 0.1 m m H 2 O 2 , 0