Emerging warriors against salinity in plants: Nitric oxide and hydrogen sulphide

Abstract

The agriculture sector is vulnerable to various environmental stresses, which significantly affect plant growth, performance, and development. Abiotic stresses, such as salinity and drought, cause severe losses in crop productivity worldwide. Soil salinity is a major stress suppressing plant development through osmotic stress accompanied by ion toxicity, nutritional imbalance, and oxidative stress. Various defense mechanisms like osmolytes accumulations, activation of stress‐induced genes, and transcription factors, production of plant growth hormones, accumulation of antioxidants, and redox defense system in plants are responsible for combating salt stress. Nitric oxide (NO) and hydrogen sulphide (H2S) have emerged as novel bioactive gaseous signaling molecules that positively impact seed germination, homeostasis, plant metabolism, growth, and development, and are involved in several plant acclimation responses to impart stress tolerance in plants. NO and H2S trigger cell signaling by activating a cascade of biochemical events that result in plant tolerance to environmental stresses. NO‐ and H2S‐mediated signaling networks, interactions, and crosstalks facilitate stress tolerance in plants. Research on the roles and mechanisms of NO and H2S as challengers of salinity is entering an exponential exploration era. The present review focuses on the current knowledge of the mechanisms of stress tolerance in plants and the role of NO and H2S in adaptive plant responses to salt stress and provides an overview of the signaling mechanisms and interplay of NO and H2S in the regulation of growth and development as well as modulation of defense responses in plants and their long term priming effects for imparting salinity tolerance in plants.

Exogenous Nitric Oxide Reinforces Photosynthetic Efficiency, Osmolyte, Mineral Uptake, Antioxidant, Expression of Stress-Responsive Genes and Ameliorates the Effects of Salinity Stress in Wheat

“…Applied NO has been found to counteract the detrimental effects of osmotic stressors, i.e., drought [ 13 ] and salinity [ 85 , 86 ]. These effects may be due to enhancing the antioxidant capacity, osmotic potential, nutrient homeostasis, and gas exchange [ 13 , 86 ].…”

Hydrogen sulfide‐mediated mitigation and its integrated signaling crosstalk during salinity stress

“…Several studies have reported that salinity stress induces endogenous production of H 2 S in crop plants, which in turn enhances salinity tolerance by modulating the activity of antioxidant enzymes, increasing the osmolyte content, regulating cell signaling proteins, maintaining ionic homeostasis as well as regulating the expression of stress-linked genes (Shi et al, 2013;Zulfiqar & Hancock, 2020). Shi et al (2013) have reported a 2-to 4-fold increase in endogenous H 2 S production compared to control in response to salinity stress in Cynodon dactylon Evelin et al, 2019;Goyal et al, 2019Goyal et al, , 2021Hasanuzzaman et al, 2014;. Also, the impairment of biological processes, such as photosynthesis, nutrient uptake, and nutrient assimilation, was reported (Farooq et al, 2015).…”

“…Due to these immensely beneficial features, the contribution of H 2 S has also been observed in the mitigation of salinity‐induced adverse effects on plant growth and development, particularly in photosynthesis, oxidative stress, and productivity (Dar et al, 2021). Further, during salinity stress alleviation, the contribution of other signaling components such as H 2 O 2 (Liu et al, 2020), NO (Goyal et al, 2021; Jahan et al, 2020), and melatonin (Li et al, 2019) was also reported, suggesting the possibility of their crosstalk. During the H 2 S‐mediated amelioration of salinity stress, H 2 S interacts either upstream or downstream to these signaling components.…”

The Modus Operandi of Hydrogen Sulfide(H2S)-Dependent Protein Persulfidation in Higher Plants

“…However, research into its role in higher plant physiology has been increasing to a significant extent particularly over the last ten years. H 2 S is now reported to be involved in virtually all physiological processes, including seed germination, root development, senescence, fruit ripening and guard cell movements [5][6][7][8], and also in mechanisms of response to adverse environmental conditions, as well as to biotic and abiotic stresses [9][10][11][12][13][14][15][16][17][18][19]. Figure 1 shows a graphical summary of the key plant processes involving H 2 S. All these wide spectra of functions exerted by H 2 S are done usually in coordination with other molecules with regulatory properties such as nitric oxide, hydrogen peroxide, carbon monoxide, melatonin, abscisic acid, gibberellins, cytokinins, or ethylene.…”

“…However, research into its role in higher plant physiology has been increasing to a significant extent particularly over the last ten years. H 2 S is now reported to be involved in virtually all physiological processes, including seed germination, root development, senescence, fruit ripening and guard cell movements [ 5 , 6 , 7 , 8 ], and also in mechanisms of response to adverse environmental conditions, as well as to biotic and abiotic stresses [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Figure 1 shows a graphical summary of the key plant processes involving H 2 S.…”