Ethylene and Sulfur Coordinately Modulate the Antioxidant System and ABA Accumulation in Mustard Plants under Salt Stress

Abstract

This study explored the interactive effect of ethephon (2-chloroethyl phosphonic acid; an ethylene source) and sulfur (S) in regulating the antioxidant system and ABA content and in maintaining stomatal responses, chloroplast structure, and photosynthetic performance of mustard plants (Brassica juncea L. Czern.) grown under 100 mM NaCl stress. The treatment of ethephon (200 µL L−1) and S (200 mg S kg−1 soil) together markedly improved the activity of enzymatic and non-enzymatic components of the ascorbate-glutathione (AsA-GSH) cycle, resulting in declined oxidative stress through lesser content of sodium (Na+) ion and hydrogen peroxide (H2O2) in salt-stressed plants. These changes promoted the development of chloroplast thylakoids and photosynthetic performance under salt stress. Ethephon + S also reduced abscisic acid (ABA) accumulation in guard cell, leading to maximal stomatal conductance under salt stress. The inhibition of ethylene action by norbornadiene (NBD) in salt- plus non-stressed treated plants increased ABA and H2O2 contents, and reduced stomatal opening, suggesting the involvement of ethephon and S in regulating stomatal conductance. These findings suggest that ethephon and S modulate antioxidant system and ABA accumulation in guard cells, controlling stomatal conductance, and the structure and efficiency of the photosynthetic apparatus in plants under salt stress.

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

“…It may be said that there is ethylene signaling in guard cells to induce changes in abscisic acid (ABA) level for stomatal movement in the presence of Glu under salt stress. Fatma et al 61 showed ethylene in the presence of sulphur induced ABA changes in guard cell, leading to increased stomatal conductance and structure and efficiency of photosynthetic apparatus in Brassica juncea under salt stress. The application of ethylene increased GSH content that led to cellular redox homeostasis and controlled stomatal movement.…”

Salicylic Acid Increases Photosynthesis of Drought Grown Mustard Plants Effectively with Sufficient-N via Regulation of Ethylene, ABA and Nitrogen-Use Efficiency

“…The content of ABA was estimated by adopting the method of Hung and Kao (2003) with small modi cations. The details are given in Fatma et al (2021) and provided in the Supplementary File 1.…”

“…Similarly, ethylene biosynthesis is stimulated under drought stress (Apelbaum and Yang 1981;Morgan and Drew 1997;Nazar et al 2015); however it is stress ethylene that has be brought to an optimum level to initiate maximum utilization of available resource. Ethylene has been found to play a role in the auxininduced opening of stomata in Vicia faba (Merrritt et al 2001) and in modulation of stomatal closure induced by ABA (Fatma et al 2021). It has been shown that using ethephon (an ethylene-releasing compound) enhanced stomatal conductance, resulting in an increase in photosynthesis (Iqbal et al 2012).…”

Involvement of Ethylene in Reversal of Salt Stress by Salicylic acid in Presence of Sulfur in Mustard (Brassica juncea L.)

“…Ethylene evolution in leaves was assessed using gas chromatograph by the process de ned previously by Fatma et al (2021).…”

“…Sulfur is a major constituent of methionine (Met) and cysteine (Cys), Fe-S clusters, sulfolipids, S-methylmethionine (SMM), S-adenosylmethionine (SAM), glucosinolates, vitamins (biotin and thiamine), coenzyme A, thioredoxin system and GSH, a major antioxidant metabolite and non-protein thiol (Fatma et al 2013;Anjum et al 2015). Applied S improved the photosynthetic capacity of the plants in salt stress by improving the cellular GSH level, modulating the major components of the ascorbate-glutathione (AsA-GSH) cycle, restricting ROS formation, and thus, minimizing oxidative stress and its consequences (Fatma et al 2021).…”