Physiological role of hydrogen sulfide in seed germination and seedling development under stress conditions

Seed germination is one of the key processes in nature, with several studies focused on improving this process. One successful strategy is to expose seeds to hydrogen sulfide (H2S), a cytotoxic reactive molecule at high concentrations, but a signaling molecule with positive physiological effects at low concentrations. This review describes and discusses (1) the signaling and physiological effects of H2S over the seeds' up-regulated antioxidant activities, to diminish the damage caused by reactive oxygen species, (2) the antagonism of H2S towards ethylene via the down-regulation and persulfidation of enzymes involved in ethylene synthase production, and also by decreasing the sensitivity of ethylene receptors, (3) the impacts of persulfidation in mitochondria and their implication in the electron transport chain, and (4) the enzymes that are affected by H2S, its interaction with abscisic acid, drought, heat, and salinity, as well as its influence on biological nitrogen fixation. H2S regulates abiotic stress tolerance by affecting stress-related genes. This review further provides an overview of the biological role of H2S in seed germination and its potential use to improve the establishment of plants. The use of H2S to establish biotechnological strategies to minimize stress factors is a promising approach to improve crop productivity.