SnRK1 as the Core Node Integrating Energy Homoeostasis, Stress Adaptation and Hormonal Crosstalk in Plants

The SnRK1 (sucrose nonfermenting 1-related protein kinase 1) plays a pivotal role in plant growth, development and stress responses. This review provides an overview of the structure, posttranslational regulation and diverse functions of SnRK1 in plants. SnRK1 is a heterotrimeric complex composed of α, β and βγ subunits, and its activity is regulated through phosphorylation, ubiquitination, SUMOylation, N-myristoylation and potentially acetylation. SnRK1 is expressed across various plant tissues and is involved in multiple cellular processes, including sugar signalling, energy homoeostasis and hormone regulation. It governs plant growth and development, ranging from seed germination to flowering and fruiting, by modulating gene expression, protein stability and metabolic pathways. Furthermore, SnRK1 plays a crucial role in the plant's response to abiotic and biotic stresses. SnRK1 also modulates plant hormone signals, thus coordinating growth and stress responses. Despite the established functional framework of SnRK1, questions regarding subunit interaction dynamics, subcellular localisation shifts and spatiotemporal specificity of posttranslational modifications remain. Future research should prioritise engineering SnRK1 signalling networks to develop stress-tolerant and energy-efficient crop germplasm. This would provide valuable insights into enhancing crop yield and stress tolerance.