LAUSR

To survive and sustain growth, sessile plants have developed sophisticated internal signalling networks that respond to various external and internal cues. Despite the central roles of nutrient and hormone signaling in plant growth and development, how hormone-driven processes coordinate with metabolic status remains largely enigmatic. Target of rapamycin (TOR) kinase is an evolutionarily conserved master regulator that integrates energy, nutrients, growth factors, hormones and stress signals to promote growth in all eukaryotes. Inspired by recent comprehensive systems, chemical, genetic and genomic studies on plant TOR, this review discusses a potential role of TOR as the global positioning system to both temporally and spatially direct plant growth and developmental programs by integrating dynamic information in the complex nutrient and hormonal signaling networks. We further evaluate and depict the possible functional and mechanistic models for how a single protein kinase TOR is able to recognize, integrate and even distinguish a plethora of positive and negative input signals to execute appropriate and distinct downstream biological processes via multiple partners and effectors.