Chapter 4 - Regulation of metal stress toxicity in plants by the hydrogen sulfide

Abstract

Hydrogen sulfide (H2S) is a gaseous signal molecule. Initially it was considered to be a toxic gaseous molecule, but recent studies have revealed its various roles in the control of plant growth and developmental. H2S exerts a positive impact on plant growth, development, and on plant tolerance against stress. It efficiently induces production of cellular enzymatic and nonenzymatic antioxidants. Pollution from heavy metals in soil, air, and water is a global problem that is causing a great loss to crop yields and exerts hazardous effects on human health when these metals enter the food chain. The heavy metals are widely used as industrial chemicals and their discharged effluents contaminate soil, water increasing their availability to plants. All stages of plant life are affected by metals. Metal stress activates endogenous H2S production and H2S alleviates metal toxicity in plants. To understand the role of H2S in alleviating metal toxicity it is necessary to review the physiological and molecular mechanisms behind the functions of H2S. In this chapter, we aim to highlight the possible role of H2S as an emerging signaling molecule involved in the regulation of several physiological processes in plants under metal stress.