O-Glycosylation as a Key Regulator of Nutrient and Stress Signaling Pathways in Plants: New Insights and Future Directions

Plants continuously adjust their growth, metabolism, and stress responses under fluctuating nutrient availability and environmental conditions. Post-translational modifications (PTMs) play essential roles in coordinating these adaptive processes; however, the contribution of O-glycosylation to nutrient-responsive signaling in plants remains insufficiently understood. This review highlights the emerging roles of O-fucosylation and O-GlcNAcylation, mediated by the glycosyltransferases SPINDLY (SPY) and SECRET AGENT (SEC), as central regulators of nutrient and energy sensing networks in plants. This review discusses how these modifications integrate carbon, nitrogen, and sugar signaling with key regulatory pathways, including SnRK1, TOR, and hormone-associated signaling cascades, to modulate plant growth, development, and stress adaptation. Emphasis is placed on the dynamic crosstalk between O-glycosylation and other PTMs, such as phosphorylation and ubiquitination, in regulating protein stability, signaling specificity, and metabolic homeostasis under changing environmental conditions. Recent advances in glycoproteomic approaches, proximity-labeling proteomics, CRISPR-based genome editing, and multi-omics integration have significantly accelerated the identification and functional characterization of O-glycosylated proteins in plants. From an applied perspective, we further discuss the potential of targeting O-glycosylation pathways to improve nutrient-use efficiency, stress resilience, and sustainable crop productivity under climate change scenarios. Collectively, this review provides an updated framework for understanding the regulatory significance of O-glycosylation in plant nutrient signaling and highlights its emerging potential in future crop improvement strategies.