Functions and interactions of important sulfur-containing metabolites in plant development and stress responses

Sulfur (S), an essential macroelement, plays important roles in plant numerous physiological processes. Through sulfur assimilation pathways, plants biosynthesize various S-containing compounds, including the gasotransimitter hydrogen sulfide (H2S), the primary organic S-containing amino acid cysteine (Cys), the master antioxidant glutathione (GSH), and the characteristic secondary metabolites such as glucosinolates (GSLs). Current studies have established the wide involvement of S-containing metabolites in orchestrating plant development and stimuli responses, however, the interplay and crosstalk among these molecules in coordinating these processes remain limited. This review systematically synthesizes current knowledge on sulfur assimilation and the multifaceted functions of S-containing metabolites in plants, encompassing their roles in ROS and intracellular sulfur homeostasis, protein redox modifications, and their function as signaling molecules that interact with plant hormones and other growth regulators. We also specifically delineate the functional interactions and crosstalk among some metabolites, with a focus on the paired relationships between H2S and Cys, H2S and GSH, H2S and GSLs, Cys and GSLs, and GSH and GSLs, during plant development and stress adaptation. We expect that this review will establish a comprehensive framework for understanding the regulation of sulfur metabolism and elucidate the mechanistic basis of S-containing metabolites in physiological processes. By integrating recent advances in this field, we aim to provide not only fundamental insights into sulfur nutrient utilization efficiency, but also valuable theoretical support for developing innovative strategies in crop improvement and sustainable agriculture.