Involvement of l-Cysteine Desulfhydrase and Hydrogen Sulfide in Glutathione-Induced Tolerance to Salinity by Accelerating Ascorbate-Glutathione Cycle and Glyoxalase System in Capsicum

Abstract

<jats:p>The aim of this study is to assess the role of L-cysteine desulfhydrase (L-DES) and endogenous hydrogen sulfide (H2S) in glutathione (GSH)-induced tolerance to salinity stress (SS) in sweet pepper (Capsicum annuum L.). Two weeks after germination, before initiating SS, half of the pepper seedlings were retained for 12 h in a liquid solution containing H2S scavenger, hypotaurine (HT), or the L-DES inhibitor DL-propargylglycine (PAG). The seedlings were then exposed for three weeks to control or SS (100 mmol L−1 NaCl) and supplemented with or without GSH or GSH+NaHS (sodium hydrosulfide, H2S donor). Salinity suppressed dry biomass, leaf water potential, chlorophyll contents, maximum quantum efficiency, ascorbate, and the activities of dehydroascorbate reductase, monodehydroascorbate reductase, and glyoxalase II in plants. Contrarily, it enhanced the accumulation of hydrogen peroxide, malondialdehyde, methylglyoxal, electrolyte leakage, proline, GSH, the activities of glutathione reductase, peroxidase, catalase, superoxide dismutase, ascorbate peroxidase, glyoxalase I, and L-DES, as well as endogenous H2S content. Salinity enhanced leaf Na+ but reduced K+; however, the reverse was true with GSH application. Overall, the treatments, GSH and GSH+NaHS, effectively reversed the oxidative stress and upregulated salt tolerance in pepper plants by controlling the activities of the AsA-GSH and glyoxalase-system-related enzymes as well as the levels of osmolytes.</jats:p>

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 maintenance of the GSH pool under K + supplementation is indicative of normal functioning of the AsA–GSH cycle which invariably maintains a higher AsA:DHA and GSH:GSSG ratio ( Figure 5 A–C and Figure 6 A–C), thus facilitating the maintenance of redox homeostasis [ 19 , 33 ]. Increased levels of LCD/DCD activity and H 2 S content during K + supplementation indicate their possible role in glutathione-mediated antioxidative defense [ 32 , 34 ]. K + -induced elevation in the AsA:DHA and GSH:GSSG ratio aligns well with the increase in the activity of antioxidant enzymes, namely APX, GR, SOD, POX, and CAT ( Figure 7 A,B and Figure 8 A–C).…”

“…K + -induced elevation in the AsA:DHA and GSH:GSSG ratio aligns well with the increase in the activity of antioxidant enzymes, namely APX, GR, SOD, POX, and CAT ( Figure 7 A,B and Figure 8 A–C). GSH and H 2 S are likely to exert a synergistic role in imparting NaCl stress tolerance [ 34 ]. Here, we report that exogenous K + -mediated endogenous H 2 S levels and GR activity under NaCl stress cause modulation of GSH content.…”

“…Here, we report that exogenous K + -mediated endogenous H 2 S levels and GR activity under NaCl stress cause modulation of GSH content. Earlier evidence suggests the positive effect of GSH in upregulating LCD activity and H 2 S biosynthesis in salt-stressed pepper plants [ 34 ]. In the present work, a K + -induced surge in GSH levels is in good agreement with enhanced LCD/DCD activity and higher accumulation of H 2 S in tomato seedling roots under NaCl stress.…”

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

“…lycopericum L. (MT and MT‐Well, respectively) exposed to salinity stress. Likewise, the endogenous production of H 2 S increased by >50% compared to control in response to salinity stress in Capsicum annum L., which improved salinity tolerance (Kaya et al, 2020a). Therefore, salinity stimulates l ‐DES activity in several plants, which in turn enhances the endogenous production of H 2 S that subsequently assists plants in reducing salinity‐induced negative features, thus boosting salt tolerance.…”

Hydrogen sulfide: an emerging component against abiotic stress in plants

“…H 2 S and Ca 2+ act synergistically and induce H + -ATPase activity that creates a H + gradient and induces the Na + /H + antiport system in Vigna radiata seedlings under NaCl stress (Khan et al 2021b). Kaya et al (2020d) explored the role of H 2 S and L-Cys desulfhydrase (LDES) in glutathione-induced resilience to salinity stress (NaCl, 100 mmol l À1 ) in Capsicum annuum L. (sweet pepper). Before applying salt stress, 2-week-old plantlets were treated with the H 2 S scavenger hypotaurine (HT) and the LDES inhibitor DL-propargylglycine (PAG).…”