Effects of Different Treatments of Salicylic Acid on Heat Tolerance, Chlorophyll Fluorescence, and Antioxidant Enzyme Activity in Seedlings of Cucumis sativa L. |
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Authors: | Qinghua Shi Zhiyi Bao Zhujun Zhu Quansheng Ying Qiongqiu Qian |
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Institution: | (1) Department of Horticulture, Zhejiang University, Hangzhou, 310029, PR China;(2) Key Laboratory of Horticultural Plant Development and Biotechnology, Ministry of Agriculture, Zhejiang University, Hangzhou, 310029, PR China;(3) College of Horticultural Science and Engineering, Shandong Agricultural University, Taian, 271018, PR China |
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Abstract: | The effects of different treatments of salicylic acid (SA) on lipid peroxidation, chlorophyll fluorescence and antioxidant
enzyme activity in seedlings of Cucumis sativa L. were studied before heat stress treatment, 36 h after heat stress and 24 h after recovery. Compared with the controls
(foliar spray of distilled water), a foliar spray of 1 mM SA (SSA treatment) decreased electrolyte leakage and the concentration
of H2O2 and thiobarbituric acid reactive substances (TBARS). SSA treatment also enhanced maximum yield of photosystem II photochemical
reactions (Fv/Fm) and the quantum yield of the photosystem II electron transport (ΦPSII) after both heat stress and recovery;
however, adding 1 mM SA to the nutrient solution (ASA treatment) or both adding 1 mM SA to the nutrient solution and foliar
spray of 1 mM SA as well (SSA + ASA treatment) had the opposite effects. SOD activity was stimulated by all SA treatments.
CAT activity was stimulated by SSA treatment and inhibited by ASA and SSA + ASA treatments after heat stress and recovery.
This suggest that SSA treatment can efficiently remove H2O2 and decrease heat stress, and CAT plays a key role in removing H2O2 in cucumber seedlings under heat stress, while more H2O2 accumulates in ASA and SSA + ASA treatments and therefore induces serious oxidative stress. GPX, APX and GR showed higher
activities in all SA treatments under heat stress, however, it appears that they were not key enzymes in removing H2O2 in cucumber subject to heat stress. |
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Keywords: | Ascorbate peroxidase Catalase Cucumber Dehydroascorbate reductase Electrolyte leakage Fv/Fm Glutathione reductase Superoxide dimutase Thermotolerance Φ PSII |
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