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

Summary: 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. Keywords: Arabidopsis, immunity, photoperiod, temperature, DET1, COP1, PIF4, environmental signal integratio