Hydrogen sulfide: a promising gasotransmitter for alleviating heavy metal toxicity and promoting growth in plants

Since the advent of industrialization, there has been a significant increase in the accumulation of heavy metals (HMs) in the soil, which further pose a major threat to plant growth and productivity. To address this issue and meet the global demand for food and energy, it is crucial to develop strategies that mitigate the toxicity induced by increased levels of HMs. One viable option is the supplementation of various phytohormones and gasotransmitters. Gasotransmitters are well-known for their ability to counteract a plethora of stresses in plants, with multifunctional hydrogen sulfide (H2S) being a promising candidate for reducing HM- induced oxidative stress. Furthermore, H2S has also been reported to regulate various physiological processes, such as seed germination, senescence and ageing in plants both under normal and stressed conditions. This review concurrently underscores the significance of H2S in plants subjected to HM stress. It also elucidates H2S's role as both a standalone stress mitigator as well as a synergistic component when combined with other stress-alleviating agents, resulting in the mitigation of HM toxicity, enhanced plant growth, stabilization of physiological processes and the upregulation of antioxidative metabolic activities. Overall, this review accentuates the necessity for sustainable and eco-friendly approaches to manage HM stress and emphasizes the potential of H2S as a promising solution to alleviate HM-related damage to plants.