Ethylene reduces glucose sensitivity and reverses photosynthetic repression through optimization of glutathione production in salt-stressed wheat (Triticum aestivum L.)

Abstract

Ethylene plays a crucial role throughout the life cycle of plants under optimal and stressful environments. The present study reports the involvement of exogenously sourced ethylene (as ethephon; 2-chloroethyl phosphonic acid) in the protection of the photosynthetic activity from glucose (Glu) sensitivity through its influence on the antioxidant system for adaptation of wheat (Triticum aestivum L.) plants under salt stress. Ten-day-old plants were subjected to control and 100 mM NaCl and treated with 200 µl L−1 ethephon on foliage at 20 days after seed sowing individually or in combination with 6% Glu. Plants receiving ethylene exhibited higher growth and photosynthesis through reduced Glu sensitivity in the presence of salt stress. Moreover, ethylene-induced reduced glutathione (GSH) production resulted in increased psbA and psbB expression to protect PSII activity and photosynthesis under salt stress. The use of buthionine sulfoximine (BSO), GSH biosynthesis inhibitor, substantiated the involvement of ethylene-induced GSH in the reversal of Glu-mediated photosynthetic repression in salt-stressed plants. It was suggested that ethylene increased the utilization of Glu under salt stress through its influence on photosynthetic potential and sink strength and reduced the Glu-mediated repression of photosynthesis.

Exogenously-Sourced Ethylene Positively Modulates Photosynthesis, Carbohydrate Metabolism, and Antioxidant Defense to Enhance Heat Tolerance in Rice

“…Notably, maximum ethylene generation was achieved in heat-stressed plants; this was stress ethylene, and adversely affected plant growth. Several prior studies have described stress-induced ethylene formation and the importance of optimal ethylene levels [43,46]. The observed stress ethylene was reduced by ethephon application, which brought ethylene levels to an optimum and influenced the physiological and metabolic changes associated with high-temperature stress.…”

“…Through transcriptomic analysis studies, Smet and colleagues [94] determined that the expression of photosynthetic genes was altered in ethylene-treated Arabidopsis plants exposed to high CO 2 concentrations. Salt stress in wheat plants was found to suppress genes encoding PSII proteins; however, pretreatment with ethylene caused those same genes to beup-regulated instead [46]. Here, the effect of ethylene on genes encoding core PSII proteins in rice plants subjected to high-temperature stress was investigated.…”

“…The exogenous application of ethylene is known to influence the photosynthetic efficiency of PSII proteins and the expression of their encoding genes [46]. Here, the expression of two genes involved in the photosynthetic system, psbA and psbB, encoding D1 protein and CP47, respectively, were analyzed to further investigate the protective function of ethylene against high-temperature stress.…”

“…It is involved in defense by suppressing ROS formation via the activation of flavonol production in guard cells, and consequently reduces abscisic acid (ABA)-induced stomatal closure [45]. In addition, ethylene regulates carbohydrate partitioning [44], and cross-talk between glucose and ethylene has been explored [46]. In Hevea brasiliensis, ethylene increased latex production, enhanced the transcript abundance of sucrose transporters [47], and altered TREHALOSE-6-PHOSPHATE SYNTHASE expression [48].…”

Ethylene Supplementation Combined with Split Application of Nitrogen and Sulfur Protects Salt-Inhibited Photosynthesis through Optimization of Proline Metabolism and Antioxidant System in Mustard (Brassica juncea L.)

“…Ethylene signaling has been found to increase the accumulation of proline for osmotic adjustment [ 22 ]. It was reported that enhanced activity of ascorbate–glutathione cycle enzymes produced higher concentrations of GSH that reduced salt and excess glucose-induced oxidative stress in Triticum aestivum [ 23 ]. Salt tolerance was associated with increased relative water content, lower lipid peroxidation, and increased proline and polyamine accumulation accompanied by increased ethylene [ 24 ].…”