Taurine, a sulfur-containing β-amino acid abundant in animals, was long considered irrelevant to plants - a view now challenged by recent studies. This review examines its emerging roles in plants, potential applications, and underlying mechanisms. Although endogenous taurine levels are extremely low (typically μmol·kg −1 range), exogenous application promotes seed germination, root development, and photosynthesis across multiple crops. Under abiotic stresses (heavy metals, salinity, drought), taurine activates H₂S/NO signaling, upregulates antioxidant enzymes and the ascorbate-glutathione cycle, reduces lipid peroxidation, accumulates osmolytes, and remodels root architecture, thereby enhancing stress tolerance. A key controversy is critically examined: given that plants lack taurine synthesis, do these effects reflect genuine signaling or non-specific interactions? Current research is limited to a few species and single concentrations, with systematic studies on dose responses, species specificity, and molecular causality still lacking. Future directions include elucidating crosstalk with phytohormones, exploring synergy with nanocarriers or beneficial microbes, and extending research to field trials and postharvest applications. This review redefines the role of non-proteinogenic amino acids in plants and provides a foundation for developing taurine as a novel green biostimulant.
Zhang et al. (Mon,) studied this question.