Nitric Oxide and Hydrogen Sulfide Coordinately Reduce Glucose Sensitivity and Decrease Oxidative Stress via Ascorbate-Glutathione Cycle in Heat-Stressed Wheat (Triticum aestivum L.) Plants

Abstract

The involvement of nitric oxide (NO) and hydrogen sulfide (H2S) in countermanding heat-inhibited photosynthetic features were studied in wheat (Triticum aestivum L.). Heat stress (HS) was employed at 40 °C after establishment for 6 h daily, and then plants were allowed to recover at 25 °C and grown for 30 days. Glucose (Glc) content increased under HS and repressed plant photosynthetic ability, but the application of sodium nitroprusside (SNP, as NO donor) either alone or with sodium hydrosulfide (NaHS, as H2S donor) reduced Glc-mediated photosynthetic suppression by enhancing ascorbate-glutathione (AsA-GSH) metabolism and antioxidant system, which reduced oxidative stress with decreased H2O2 and TBARS content. Oxidative stress reduction or inhibiting Glc repression was maximum with combined SNP and NaHS treatment, which was substantiated by 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) and hypotaurine (HT), scavengers for NO and H2S, respectively. The scavenge of H2S reduced NO-mediated alleviation of HS suggesting of its downstream action in NO-mediated heat-tolerance. However, a simultaneous decrease of both (NO and H2S) led to higher Glc-mediated repression of photosynthesis and oxidative stress in terms of increased H2O2 content that was comparable to HS plants. Thus, NO and H2S cooperate to enhance photosynthesis under HS by reducing H2O2-induced oxidative stress and excess Glc-mediated photosynthetic suppression.

Exogenous Potassium (K+) Positively Regulates Na+/H+ Antiport System, Carbohydrate Metabolism, and Ascorbate–Glutathione Cycle in H2S-Dependent Manner in NaCl-Stressed Tomato Seedling Roots

“…The present findings are in good agreement with the role of H 2 S in the modulation of antioxidant enzymes and regulation of the AsA–GSH cycle [ 3 , 17 , 19 , 38 ]. Although ABA signaling in guard cells promotes H 2 S-mediated persulfidation of NADPH oxidases and a subsequent increase in ROS generation [ 39 ], H 2 S is also known to reduce oxidative stress by increasing the enzyme activities of the AsA–GSH pathway [ 39 , 40 ].…”

The Crosstalk of Melatonin and Hydrogen Sulfide Determines Photosynthetic Performance by Regulation of Carbohydrate Metabolism in Wheat under Heat Stress

“…The present investigation was executed on wheat (Triticum aestivum L. cultivar WH 542). The method followed by Iqbal et al [4] was adopted to carry out the experiment.…”

“…The expansion in the world's temperature because of anthropogenic activities is the significant worry for mankind [2], as this will lead to major losses in crop production worldwide [3]. The photosynthetic ability of plants gets disturbed by the enhanced production of reactive oxygen species (ROS) under high temperature [4]. ROS adversely affect enzyme activity and membrane fluidity, resulting in altered growth and development of plants and yield loss [1].…”

“…Hydrogen sulfide is the third important gasotransmitter that regulates various physiological responses under stress and play an important role in the damaging effect of heat stress [4]. It directs germination, development, senescence and plays protective role in plants [26].…”

“…Plants remobilize starch to afford carbon and energy under abiotic stress to reduce photosynthesis, but sugar released by starch degradation derived metabolites to support plant development, in addition to functioning as an osmoprotectant to mitigate stress adversities [36]. Exogenous NO and H2S enhanced photosynthesis and reduced the glucose-arbitrated photosynthetic repression in wheat under heat stress [4]. The work of Dawood and ElAwadi [37] on Vicia faba, and Wei et al [11] on soybean elaborated that melatonin supplementation increased carbohydrates accumulation that helped in salt tolerance.…”