The role of jasmonates (JAs) in root growth and development and plants response to external stimuli is already known. However, its role in lateral root (LR) development remains perplexing. Our work identifies methyl jasmonate (MeJA) as a crucial phytohormone in determining the branching angle of Arabidopsis LRs. MeJA inclines the LRs to a more vertical orientation which was dependent on JAR1-COI1-MYC2,3,4 signalling. Our work highlights the dual role of light acting with MeJA in governing the LR angle. Glucose (Glc), produced by light mediated photosynthesis induces wider branching angles. Combining physiological and molecular assays, we reveal that Glc antagonizes the MeJA response via HEXOKINASE1 (HXK1) mediated signalling and by stabilizing JAZ9. Moreover, physiological assays using auxin mutants; binding of MYC2 on the promoters of auxin biosynthetic gene CYP79B2 and LAZY2 and asymmetric distribution of DR5::GFP and PIN2::GFP pinpoints the role of an intact auxin machinery required by MeJA for vertical growth of LRs. We also demonstrate that light perception through PHYTOCHROMES (PHYA and PHYB) and LONG HYPOCOTYL5 (HY5) are indispensable for inducing vertical angles by MeJA. Thus, our investigation highlights antagonism between light and Glc signalling and how they interact with JA-auxin signals to optimize the branching angle of LRs.

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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. TORC1 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 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 analyzed the interactome and phosphoproteome of the Arabidopsis TORC1 signaling network. Our analysis highlights the role of TORC1 as a central hub kinase communicating with transcriptional and translational apparatus, ribosomes, chaperones, protein kinases, metabolic enzymes, and autophagy and stress response machinery to orchestrate growth in response to the nutrient signals. This analysis also suggests that along with the conserved downstream components shared with other eukaryotic lineages, the plant TORC1 signaling underwent several evolutionary innovations and coopted many lineage-specific components during the plant evolution. 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.