SUMMARY. Gaseous signaling molecules, originally identified in animal systems as gasotransmitters, are currently a focal point of intensive research in plant biology. In recent years, evidence for the stress-protective properties of hydrogen sulfide (H2S) has accumulated rapidly. However, the precise functional interactions between H2S-mediated post-translational modifications (PTMs) and the signaling pathways governing specific adaptive responses remain insufficiently characterized. This review consolidates current knowledge on both the primary and minor pathways of H2S biosynthesis. We analyze data concerning the PTMs of key proteins (including antioxidant enzymes, ion channels, and signaling components such as protein kinases) involved in orchestrating plant adaptation to environmental stressors. Furthermore, the interplay between H2S and other signaling intermediates, such as calcium ions (Ca2+), reactive oxygen species (ROS), and nitric oxide (NO), is discussed, particularly with regard to their shared capacity to modify target proteins. Special attention is given to the role of H2S in modulating the antioxidant defense system, activating the synthesis of stress-related metabolites, and regulating stomatal dynamics. We examine emerging data on H2S-induced PTMs of proteins that trigger shifts in ion homeostasis within guard cells. Finally, the review highlights the critical need to identify the full spectrum of cysteine persulfidation sites and to elucidate the regulatory mechanisms of PTMs in specific proteins during stress adaptation. The importance of further deciphering the functional crosstalk between H2S and stress-related phytohormones is also emphasized.
Keywords: hydrogen sulfide, signaling mediators, reactive oxygen species, calcium, nitric oxide, stress-protective systems, post-translational protein modifications
