Posttranslational regulation of TOR kinase activity controls resource allocation between plant growth and immunity in...

The resource trade-off between growth and immunity is common in plants, but the underlying molecular mechanisms remain unclear. In this study, we demonstrate that the posttranslational regulation of the Target of Rapamycin (TOR) kinase is a key determinant in maintaining this balance. Inhibiting TOR activity, either pharmacologically or genetically, enhanced root immunity and mitigated pathogen-induced root growth suppression. TOR inactivation preceded resource depletion during the early stage of infection, indicating an active resource reallocation mechanism that prioritizes defense activation over growth maintenance. Mechanistic studies uncovered a phosphorylation circuit where pathogen recognition activates the lectin receptor-like kinase LORE, which stimulates the phosphatase LOPP to directly dephosphorylate and inactivate TOR. Subsequently, LOPP is degraded via a proteasomal pathway, restoring TOR activity. This phosphorylation circuit enables plants to prioritize immune responses while maintaining growth flexibility. Our findings establish TOR as a key regulator of resource allocation during host-microbe interactions and offer a mechanistic framework for understanding growth-immunity trade-offs in plants.