Exogenously-Sourced Ethylene Positively Modulates Photosynthesis,Carbohydrate Metabolism,and Antioxidant Defense to Enhance Heat Tolerance in Rice |
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Authors: | Harsha Gautam Mehar Fatma Zebus Sehar Noushina Iqbal Mohammed Albaqami Nafees A. Khan |
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Affiliation: | 1.Plant Physiology and Biochemistry Laboratory, Department of Botany, Aligarh Muslim University, Aligarh 202002, India; (H.G.); (M.F.); (Z.S.);2.Department of Botany, Jamia Hamdard, New Delhi 110062, India;3.Department of Biology, Faculty of Applied Science, Umm Al-Qura University, Makkah 21955, Saudi Arabia |
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Abstract: | The effect of exogenously-applied ethylene sourced from ethephon (2-chloroethyl phosphonic acid)was studied on photosynthesis, carbohydrate metabolism, and high-temperature stress tolerance in Taipei-309 and Rasi cultivars of rice (Oryza sativa L.). Heat stress increased the content of H2O2 and thiobarbituric acid reactive substances (TBARS)more in Rasi than Taipei-309. Further, a significant decline in sucrose, starch, and carbohydrate metabolism enzyme activity and photosynthesis was also observed in response to heat stress. The application of ethephon reduced H2O2 and TBARS content by enhancing the enzymatic antioxidant defense system and improved carbohydrate metabolism, photosynthesis, and growth more conspicuously in Taipei-309 under heat stress. The ethephon application enhanced photosynthesis by up-regulating the psbA and psbB genes of photosystem II in heat-stressed plants. Interestingly, foliar application of ethephoneffectively down-regulated high-temperature-stress-induced elevated ethylene biosynthesis gene expression. Overall, ethephon application optimized ethylene levels under high-temperature stress to regulate the antioxidant enzymatic system and carbohydrate metabolism, reducing the adverse effects on photosynthesis. These findings suggest that ethylene regulates photosynthesis via carbohydrate metabolism and the antioxidant system, thereby influencing high-temperature stress tolerance in rice. |
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Keywords: | antioxidant ethephon carbohydrate high-temperature stress photosynthesis |
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