Exogenous Hydrogen Sulfide Supplementation Alleviates the Salinity-Stress-Mediated Growth Decline in Wheat (Triticum aestivum L.) by Modulating Tolerance Mechanisms

Abstract

The impact of the exogenous supplementation of hydrogen sulfide (20 and 50 µM HS) on growth, enzyme activity, chlorophyll pigments, and tolerance mechanisms was studied in salinity-stressed (100 mM NaCl) wheat. Salinity significantly reduced height, fresh and dry weight, chlorophyll, and carotenoids. However, the supplementation of HS (at both concentrations) increased these attributes and also mitigated the decline to a considerable extent. The exogenous supplementation of HS reduced the accumulation of hydrogen peroxide (H2O2) and methylglyoxal (MG), thereby reducing lipid peroxidation and increasing the membrane stability index (MSI). Salinity stress increased H2O2, MG, and lipid peroxidation while reducing the MSI. The activity of nitrate reductase was reduced due to NaCl. However, the supplementation of HS alleviated the decline with obvious effects being seen due to 50 µM HS. The activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) was assayed and the content of reduced glutathione (GSH) increased due to salt stress and the supplementation of HS further enhanced their activity. A decline in ascorbic acid due to salinity stress was alleviated due to HS treatment. HS treatment increased the endogenous concentration of HS and nitric oxide (NO) under normal conditions. However, under salinity stress, HS supplementation resulted in a reduction in HS and NO as compared to NaCl-treated plants. In addition, proline and glycine betaine increased due to HS supplementation. HS treatment reduced sodium levels, while the increase in potassium justified the beneficial role of applied HS in improving salt tolerance in wheat.

Hydrogen sulfide-mitigated salinity stress impact in sunflower seedlings was associated with improved photosynthesis performance and osmoregulation

“…The H 2 S priming alleviated these cellular aberrations of the mesophyll cells by H 2 S role in biomembrane repairing [ 34 ], ROS scavenging, Na + , and Cl − uptake restriction as well as K + and Ca 2+ content elevation [ 35 ], resulting in membrane integrity and osmotic balance maintenance reflected in the elevated value of MSI found in this work. Alamer [ 84 ] also reported a similar alleviating impact on the MSI by H 2 S supply under salinity stress in wheat.…”

“…The Rubisco small subunit is indicated to be a potential engineering target to improve the performance of Rubisco [ 19 ], and based on our findings, we recommend it for engineering biology approaches to modulate Rubisco catalysis activating the photosynthesis and hence crop performance under saline conditions. In addition, the accumulation of different osmolytes (soluble sugars, soluble proteins, and carotenoids) in the sunflower seedlings in response to H 2 S priming in the current study, is suggestive of their role in protecting the architecture and functions of the chloroplast membranes, enzymes, and other cell structures against ROS damage and the toxicity of greater concentrations of intracellular toxic ions, as well as acting as osmotic regulators [ 18 , 34 , 81 – 84 ], which resulted in enhanced photosynthesis, stabilized subcellular structures, and osmotic adjustment, and ultimately the adaptability of sunflower seedlings to NaCl stress. Moreover, NaCl-enhanced burst of proline in sunflower seedlings (more so in roots) might be associated with salinity-induced ABA content observed in this research as ABA has been reported to elevate proline production in various stressed plants under saline conditions [ 85 , 86 ].…”