Silicon is dependent on hydrogen sulphide to improve boron toxicity tolerance in pepper plants by regulating the AsA-GSH cycle and glyoxalase system

• Published in: Chemosphere (Oxford) 2020-10, Vol.257, p.127241-127241, Article 127241
• Main Authors: Kaya, Cengiz, Ashraf, Muhammad, Al-Huqail, Asma A., Alqahtani, Moneerah A., Ahmad, Parvaiz
• Format: Article
• Language: English
• Subjects: Antioxidant defence system; Boron toxicity; Hydrogen sulphide; Oxidative stress; Pepper; Silicon
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.127241

The role of endogenous hydrogen sulphide (H2S) in silicon-induced improvement in boron toxicity (BT) tolerance in pepper plants was studied. Two-week old seedlings were subjected to control (0.05 mM B) or 2.0 mM BT in a nutrient solution. These two treatments were combined with 2.0 mM Si. BT caused considerable reduction in biomass, chlorophyll a &b, photosystem II maximum quantum efficiency (Fv/Fm), glutathione and ascorbate in the pepper seedlings. However, it enhanced malondialdehyde (MDA) and hydrogen peroxide, electrolyte leakage, proline, H2S, and activities of catalase, superoxide dismutase, peroxidase, and L-DES. Silicon stimulated growth, proline content and activities of various antioxidant biomolecules and enzymes, leaf Ca2+, K+ and N, endogenous H2S and L-DES activity, but reduced H2O2 and MDA contents, membrane leakage and leaf B. Silicon-induced B tolerance was further enhanced by 0.2 mM NaHS, a H2S donor. A scavenger of H2S, hypotaurine (0.1 mM HT), was supplied together with Si and Si + NaHS to assess the involvement of H2S in Si-induced BT tolerance of pepper plants. Hypotaurine inverted the positive role of Si on the antioxidant defence system by reducing endogenous H2S, but NaHS supply along with Si + HT reversed the negative effects of HT, showing that H2S participated in Si-induced BT tolerance of pepper plants. •Boron toxicity (BT) decreased plant growth and increased oxidative stress.•Silicon (Si) reversed the oxidative stress and BT-induced growth inhibition.•Si activated l-cysteine desulfhydrase (L-DES) and enhanced hydrogen sulphide (H2S).•Si enhanced antioxidants, K+ and Ca2+ contents and reduced B in the pepper plants.•H2S scavenger, hypotaurine (HT) reversed the H2S synthesis and antioxidant defence systems, and aggravated oxidative stress.