Chapter 18 - Role of sulfhydryl bioregulator thiourea in mitigating drought stress in crops

Abstract

Drought stress in agriculture is a global problem, as over 80% of the global cropland is under rainfed cultivation often affected by water scarcity and drought stress. The problem of drought stress has become more frequent and severe due to the continuing climate change phenomena worldwide. So far, plant breeding and biotechnology schemes have not been successful in developing drought-resilient varieties of crops in a large measure to benefit the farmers. Hence, bioregulatory molecules appear to hold promise for imparting drought tolerance to crop plants by way of modulating metabolic reprogramming and plant signaling, enabling their acclimation to drought stress conditions. Thiourea (TU), a sulfhydryl compound, has been found to alleviate drought stress in crops and improve yields as well. TU has shown efficacy in improving phloem transport, source–sink communication and maintaining redox homeostasis in crops. TU has also been found to improve thiol metabolism, and thus possibly activates glutaredoxin and thioredoxin systems, thereby maintaining thiol redox homeostasis under oxidative stress conditions. Recent investigations have revealed that TU possesses the property of releasing H2S, which has a signaling role, enabling plants for adaptation to adverse environmental conditions. In this process, TU regulates the expression of water channel protein aquaporin and improves phloem water transport in plants, thus maintaining cellular water homeostasis and facilitating plant acclimation to drought stress. An attempt has been made in this article to highlight the role of TU in H2S signaling, thiol redox homeostasis and aquaporin regulation for mitigating drought stress in crops. Taken together, the pharmacological approach of using sulfhydryl bioregulator TU offers great opportunities for mitigating drought stress and enhancing yield of crops under the present scenario of climate change and global warming.