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Sukhvinder Pal Singh and Zora Singh

· − ), hydrogen peroxide (H 2 O 2 ), nitric oxide (NO · ), and peroxynitrite (ONOO · ) are produced in plants under normal and stress conditions ( Apel and Hirt, 2004 ). If these are not removed or detoxified by the enzymatic and non-enzymatic antioxidants, they

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Samson Zeray Tesfay, Sakhile Mathe, Albert T. Modi, and Tafadzwanashe Mabhaudhi

stresses such as drought and heat stress. ELVs have long been recognized as abundant sources of nutritious essential nutrients ( Aletor et al., 2002 ; Shukla et al., 2006 ). They produce nutritious low molecular mass nonenzymatic, enzymatic antioxidants

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Safwan Shiyab

tolerant to Cr stress because its roots take up less Cr, which results in lesser transport to the shoots. In addition, it is more effective in establishing an enzymatic antioxidant system. Conclusion Accumulation of Cr in plant tissues induced

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Huifei Shen, Bing Zhao, Jingjing Xu, Xizi Zheng, and Wenmei Huang

of the Trizol reagent with H 2 O 2 and Coomassie brilliant blue (Jiancheng, Nanjing, China). The products were stored at 4 °C. Enzymatic antioxidant system. A crude enzyme was extracted from the homogenate of 0.1 g fresh leaf tissue in a 50 m m

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Clíssia Barboza da Silva, Julio Marcos-Filho, Pablo Jourdan, and Mark A. Bennett

Drum priming systems are among the most common methods of seed priming for commercial treatment. The supply of water to the seeds is controlled by physical means, and seeds are able to reach a desired moisture content without the use of osmotic solutions for hydration control. The brassinosteroid (BR), 24-epibrassinolide (24-EpiBL), has been shown previously to have a significant effect on seed performance. Therefore, the aim of this study was to verify the feasibility of drum priming associated with added 24-EpiBL on enhancement of bell pepper seed performance. Two bell pepper cultivars (AF-6 and AF-7) were tested, and each cultivar represented, respectively, by three and four seed lots with different initial physiological potentials. Seed performance was determined by evaluating standard germination, initial seedling growth, and changes on the antioxidant activity of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). Seed Vigor Imaging System (SVIS®) was used to assess the initial seedling growth. The nondenaturing polyacrylamide gel electrophoresis (PAGE) technique was used to evaluate possible changes in the enzymatic antioxidant system. Several advantages were verified in the drum priming technique with added 24-EpiBL compared with the traditional procedure (water alone). Germination time was reduced followed by a seedling growth increase. Concomitantly, seed enzymatic activity was improved. However, results showed different response for each enzyme. Drum priming with 24-EpiBL demonstrates viability for commercial treatment and enhancement of bell pepper seeds.

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Rosa Vilaplana, M. Carme Valentines, Peter Toivonen, and Christian Larrigaudière

In order to determine the effects that 1-methylcyclopropene (1-MCP) may have on antioxidant metabolism during cold storage, apples (Malus ×domestica Borkh. cv. Golden Smoothee) were treated with 625 nL·L−1 1-MCP immediately after harvest and stored in air for 3 months. Differences in total antioxidant activity and ascorbate levels were determined during storage and related to the activity of the antioxidant enzymes superoxide dismutase [SOD (EC 1.15.1.1)], catalase [CAT (EC 1.11.1.6)], and peroxidase [POX (EC 1.11.1.7)] in pulp. The level of oxidative stress in the pulp tissue was also established by determining changes in levels of hydrogen peroxide and in the content of peroxidative markers during storage. Controls and 1-MCP-treated fruit exhibited similar changes in total antioxidant activity and ascorbate levels. However, significant differences in oxidative stress levels were found between treated and untreated fruit. 1-MCP-treated fruit exhibited lower levels of hydrogen peroxide and significantly lower levels in peroxidative markers, especially at the end of the storage period. In line with this last result, 1-MCP-treated fruit also exhibited greater enzymatic antioxidant potential and, more specifically, a higher level of POX activity. Collectively, these results showed that 1-MCP did not detrimentally affect the antioxidant potential of the fruit and provided evidence to support the hypothesis that the beneficial effects of 1-MCP on ripening are not exclusively limited to its effect on ethylene, but also include direct effects on peroxidation and POX enzyme activity.

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Feng wang Ma and Lailiang Cheng*

About 80 days after full bloom, well-exposed fruit on the south part of the canopy of mature Liberty/M.9 apple trees were randomly assigned to one of the following two treatments. Some fruit were turned about 180 degrees to expose the original shaded side to full sun whereas the rest served as untreated controls. On day 0, 1, 2, 4, 7, and 10 after treatment, fruit peel samples were taken from the original shaded side of the treated fruit and both the sun-exposed side and the shaded side of the control fruit at midday to determine photosynthetic pigments and enzymatic and non-enzymatic antioxidants. Maximum photosystem II efficiency of the original shaded side decreased sharply after 1 day exposure to full sun, and then gradually recovered to a similar value of the sun-exposed side of the control fruit by day 10. The shaded side of the control fruit had much lower xanthophyll cycle pool size and conversion and antioxidant enzymes and soluble antioxidants of the ascorbate-glutathione cycle than the sun-exposed side. In response to full sun exposure, xanthophyll cycle pool size of the original shaded side increased, reaching a similar value of the sun-exposed side by day 10. Ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase and total pool size and reduction state of both ascorbate and glutathione of the original shaded side all increased to the corresponding values found in the sun-exposed side of the control fruit over a 10-day period. It is concluded that both xanthophyll cycle and the ascorbate-glutathione cycle in the original shaded side are up-regulated in response to fullsun exposure to minimize photo-oxidative damage and contributes to its re-acclimation to full sun.

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Mohamad-Hossein Sheikh-Mohamadi, Nematollah Etemadi, and Mostafa Arab

enzymatic antioxidant systems, APX and POD are essential enzymes in the cyclic activities of plants. APX and POD are necessary to transform H 2 O 2 to H 2 O and O 2 within the GSH–ascorbate cycle in chloroplasts ( Sheikh-Mohamadi et al., 2017c ). After 8

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

tolerance. We hypothesized that 1) AMF will increase growth and nutrient uptake of the affected heat-stressed asparagus plants, 2) the increased activity of enzymatic antioxidants in mycorrhizal asparagus imply that the AMF symbiosis can alleviate ROS damage

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Liyuan Huang, Jun Yuan, Hui Wang, Xiaofeng Tan, and Genhua Niu

radical (O 2 − ) ( Bartels and Sunkar, 2005 ), which may break the balance between generation and scavenging of the ROS. To detoxify Al-induced ROS, plants employ enzymatic antioxidants, such as POD, SOD, and CAT ( Boscolo et al., 2003 ; Inostroza