Growing of the TOR world

Twenty years have passed since the identification of the target of rapamycin (TOR) protein kinase in Arabidopsis. Research has expanded from functional characterization of the TOR complex (TORC1) and development of specific chemical inhibitors, to mapping the diverse biological relationships upstream and downstream of TORC1. New insights have been obtained on the mechanisms linking environmental perception to TORC1-mediated growth responses under optimal and stress conditions. Furthermore, molecular connections have been established between TORC1 and several phytohormone and nutrient signalling pathways (e.g. brassinosteroids, ethylene, and nitrogen), which together reinforce this pathway as a major hub controlling growth responses from unicellular algae to flowering plants.