Sugar sensors in plants: Orchestrators of growth, stress tolerance, and hormonal crosstalk

Sugars, vital metabolites for cellular health, play a central role in regulating diverse intracellular pathways that control plant growth and development. They also enhance stress responses, enabling plants to endure adverse conditions. A few intracellular molecules involved in sensing the intracellular sugar content and concomitantly facilitating appropriate response (growth or survivability) are known as sugar sensors. Among the numerous sugar sensors identified in plants, this review focuses on four extensively studied sugar sensors, namely hexokinase (HXK), Sucrose non-fermenting 1-related kinase-1 (Snf1-related kinase-1 or SnRK1), Target of rapamycin (TOR), and trehalose 6-phosphate (T6P). This review explores the multifaceted functions of these sugar sensors, highlighting their critical role in balancing energy metabolism and coordinating physiological processes under optimal and adverse conditions. By analyzing their involvement in plant growth, development, and stress response, this review underscores the significance of these sensors throughout the plant life cycle. Furthermore, this review highlights the intricate interplay among these sugar sensors, demonstrating how their activities are finely tuned and interdependent. We also examined the crosstalk between these sugar sensors and phytohormones, fine-tuning plant responses to environmental stimuli. Altogether, this review elucidates the significance of sugar sensors as integrators of metabolic and hormonal signals, providing a comprehensive understanding of their pivotal roles in plant biology. This knowledge paves the way for potential agricultural innovations to enhance crop productivity and resilience in the face of climate change.