DET1 and COP1 Modulate the Coordination of Growth and Immunity in Response to Key Seasonal Signals in Arabidopsis

Plant growth and development and outcomes of plant-microbe interactions are defined by coordinated responses to seasonal signals. The mechanisms that control the coordinated regulation of growth and immunity are not well understood. Here, we show that a common signaling module integrates environmental signals, such as photoperiod and temperature, to regulate the growth-defense balance. Key light-signaling components De-Etiolated 1 (DET1) and Constitutive Photomorphogenic 1 (COP1) negatively regulate immunity and are essential for immune modulation by photoperiod and temperature. Our results show that this is regulated by the transcription factor Phytochrome Interacting Factor 4 (PIF4), suggesting that the DET1/COP1-PIF4 module acts as a central hub for the control of growth and immunity in response to seasonal signals. These findings provide a regulatory framework for environmental signal integration. In plants, adaptive traits such as growth and immunity are strongly influenced by the environment. How multiple seasonal signals are integrated is not well understood. Gangappa and Kumar show that a common signaling module comprising DET1, COP1, and PIF4 coordinates growth and immunity in response to key seasonal signals.