TOR Regulation of Plant Growth

The Target of Rapamycin (TOR) kinase, a highly conserved master regulator of growth, integrates nutrient and energy signals to coordinate developmental processes. However, the mechanisms by which TOR senses and responds to specific nutrient signals remain largely unexplored. In collaboration with Dr. Hatem Rouached (MSU PRI), our research investigates how plants adapt their growth to nutrient deficiencies, with a particular focus on root responses to phosphorus (P), an essential yet non-renewable macronutrient. P scarcity triggers early and significant changes in root system architecture, making it vital to understand the molecular mechanisms underlying these adaptations. Using the model plant Arabidopsis thaliana, the study aims to elucidate the regulatory networks that connect P sensing with growth control mechanisms exerted by TOR, particularly through a newly identified signaling pathway. Central to this pathway is Arabidopsis Root-Specific Kinase 1 (ARSK1), a key regulator of early root growth under P-limited conditions. Our recent findings reveal that ARSK1 directly interacts with and regulates the TOR complex. The research focuses on unraveling the transcriptional regulation of ARSK1 by specific transcription factors and how its protein levels are modulated by a P-induced ubiquitin E3 ligase. Additionally, the team is investigating how ARSK1 modulates TOR signaling to fine-tune root growth in response to P availability. Through a combination of computational, biochemical, and molecular physiology approaches, the project seeks to uncover how ARSK1 and its downstream components mediate nutrient-responsive growth. By dissecting this pathway, the research aims to map the signaling cascade that connects P availability to TOR activity, ultimately linking nutrient sensing with the control of organ growth.