The social network of target of rapamycin complex 1 in plants

The target of rapamycin complex 1 (TORC1) is a highly conserved
serine–threonine protein kinase crucial for coordinating growth according
to nutrient availability in eukaryotes. It works as a central integrator
of multiple nutrient inputs such as sugar, nitrogen, and phosphate and
promotes growth and biomass accumulation in response to nutrient
sufficiency. Studies, especially in the past decade, have identified the
central role of TORC1 in regulating growth through interaction with
hormones, photoreceptors, and stress-signaling machinery in plants. In
this review, we comprehensively analyse the interactome and
phosphoproteome of the Arabidopsis TORC1 signaling network. Our analysis
highlights the role of TORC1 as a central hub kinase communicating with
the transcriptional and translational apparatus, ribosomes, chaperones,
protein kinases, metabolic enzymes, and autophagy and stress response
machinery to orchestrate growth in response to nutrient signals. This
analysis also suggests that along with the conserved downstream components
shared with other eukaryotic lineages, plant TORC1 signaling underwent
several evolutionary innovations and co-opted many lineage-specific
components. Based on the protein–protein interaction and phosphoproteome
data, we also discuss several uncharacterized and unexplored components of
the TORC1 signaling network, highlighting potential links for future
studies.