A molecular framework for light and gibberellin control of cell elongation Light and gibberellins (GAs) antagonistically regulate cell elongation during seedling development. Light induces photomorphogenesis, inhibiting hypocotyl growth, while GAs promote etiolated growth, characterized by increased hypocotyl elongation. The transcription factor PIF4 plays a central role in promoting cell elongation genes and is negatively regulated by the light photoreceptor phyB and DELLA proteins, which repress GA signaling. PIF4 is destabilized by phyB in the light and its transcriptional activity is blocked by DELLA proteins through DNA-binding domain interaction. GAs promote DELLA destabilization, leading to increased free PIF4 in the nucleus and activation of PIF4-regulated genes. Transgenic plants over-accumulating both DELLA and PIF4 exhibit intermediate hypocotyl lengths. PIF4 interacts with DELLA proteins, and DELLA repressors block PIF4 DNA-binding ability. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is destabilized by phyB in the light and by DELLA proteins in the dark. PIF4 and DELLA proteins interact through their bHLH domains, and this interaction is crucial for integrating light and GA signals to regulate hypocotyl growth. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteinsA molecular framework for light and gibberellin control of cell elongation Light and gibberellins (GAs) antagonistically regulate cell elongation during seedling development. Light induces photomorphogenesis, inhibiting hypocotyl growth, while GAs promote etiolated growth, characterized by increased hypocotyl elongation. The transcription factor PIF4 plays a central role in promoting cell elongation genes and is negatively regulated by the light photoreceptor phyB and DELLA proteins, which repress GA signaling. PIF4 is destabilized by phyB in the light and its transcriptional activity is blocked by DELLA proteins through DNA-binding domain interaction. GAs promote DELLA destabilization, leading to increased free PIF4 in the nucleus and activation of PIF4-regulated genes. Transgenic plants over-accumulating both DELLA and PIF4 exhibit intermediate hypocotyl lengths. PIF4 interacts with DELLA proteins, and DELLA repressors block PIF4 DNA-binding ability. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is destabilized by phyB in the light and by DELLA proteins in the dark. PIF4 and DELLA proteins interact through their bHLH domains, and this interaction is crucial for integrating light and GA signals to regulate hypocotyl growth. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins. PIF4 is a key transcription factor in the integration of light and GA signals, and its activity is regulated by phyB and DELLA proteins. PIF4 is a positive regulator of cell elongation, and its activity is inhibited by DELLA proteins