Expanding roles of cross-talk between hydrogen sulfide and nitric oxide under abiotic stress in plants

Abiotic stress such as salt, heavy metals, drought, temperature, and others can affect plants from seed germination to seedling growth to reproductive maturity. Abiotic stress increases reactive oxygen species and lowers antioxidant enzymes in plants resulted the plant tolerance ability against stress conditions decrease. Hydrogen sulfide (H₂S) and nitric oxide (NO) are important gasotransmitters involved in seed germination, photosynthesis, growth and development, metabolism, different physiological processes and functions in plants. In plants, various enzymes are responsible for the biosynthesis of both H₂S and NO via both enzymatic and non-enzymatic pathways. They also mediate post-translation modification, such as persulfidation, and nitrosylation, which are protective mechanisms against oxidative damage. They also regulate some cellular signalling pathways in response to various abiotic stress. H₂S and NO also stimulate biochemical reactions in plants, including cytosolic osmoprotectant accumulation, reactive oxygen species regulation, antioxidant system activation, K⁺ uptake, and Na⁺ cell extrusion or vacuolar compartmentation. In this review, we summarize how H₂S and NO interact with each other, the function of both H₂S and NO, the mechanism of biosynthesis, and post-translational modification under different abiotic stress. Our main emphasis was to find the cross-talk between NO and H₂S and how they regulate genes in plants under abiotic stress.