Lysine acetylation drives metabolic reprogramming for desiccation tolerance in the desert moss <i>Syntrichia caninervis</i>

Lysine acetylation represents a pivotal regulatory layer in plant stress responses, yet its functional significance in desiccation-tolerant (DT) species remains uncharacterized. Here, we report a comprehensive lysine acetylome of the extremophyte Syntrichia caninervis (S. caninervis) through dehydration-rehydration cycles, identifying 11,474 acetylation sites on 4,171 proteins and representing a large dataset of lysine acetylome in plants. Acetylation dynamics coordinated a metabolic reprogramming crucial for survival: during dehydration, acetylated proteins were enriched in carbon fixation, glutathione metabolism, and nucleotide sugar biosynthesis, facilitating structural reinforcement and redox homeostasis. Upon rehydration, acetylation rapidly targeted core metabolic pathways, including glycolysis and the proteasome, to power recovery. Notably, the extensive acetylation of glycolytic enzymes likely facilitates the rapid recovery of S. caninervis from dehydration. Functional validation established that acetylation at lysine 513 (K513) of pyruvate kinase (cPK5) is essential for its catalytic activity and required for desiccation tolerance. Our study provides an in vivo acetylome landscape of a DT plant, delineating the dynamic regulatory network that coordinates metabolic adaptation to water stress and offering a key resource for engineering drought resilience.