Mechanistic Insights into PTM-Mediated Architectural Rewiring of the Leaf Senescence Program

Leaf senescence is a highly coordinated developmental program essential for nutrient remobilization and plant fitness. While the underlying transcriptional and epigenetic landscapes have been extensively mapped, emerging evidence identifies post-translational modifications (PTMs) as the primary regulatory hubs providing the requisite sensitivity and precision for senescence signaling. This review systematically delineates the mechanistic contributions of diverse PTMs-including phosphorylation, ubiquitination, acetylation, methylation, glycosylation, lipidation, hydroxylation, S-nitrosylation, and oxidative PTMs-to the architectural rewiring of the senescence program. Rather than functioning merely as downstream effectors, PTMs operate as integrated "execution" and "decision-making" layers that bridge environmental inputs, hormonal fluxes, and metabolic status. By dynamically modulating key senescence-associated transcription factors (e.g., ORE1, WRKY53), kinase cascades, and autophagy-related networks, PTM registries facilitate the initiation, amplification, and irreversible commitment of leaf cells to senescence. Furthermore, we discuss how the interplay and crosstalk among distinct modification types establish a sophisticated combinatorial logic for sensing physiological thresholds. By integrating recent advances in single-cell proteomics and spatial omics, this synthesis highlights the paradigm shift toward cell-type-specific PTM atlases. Ultimately, these molecular insights provide a robust theoretical framework for the precision engineering of crop senescence to enhance resilience and yield.