Transcriptional factor interaction: a central step in DELLA function.

Gibberellins (GAs) affect several growth and developmental responses during the plant life cycle. Components essential for GA perception and GA signaling have been identified in rice and Arabidopsis and are conserved among vascular plants but not in Physcomitrella patens. The recent observation that DELLAs bind in nuclei to different members of the phytochrome interacting factor family, to block their transcriptional activity, is an important breakthrough to the understanding of the functional mechanism of these repressors. Beyond its role in GA-signaling repression, DELLAs were found to regulate GA homeostasis and to represent a convergence point for other hormone-signaling pathways. These repressors impose a growth restraint under environmental adverse conditions, allowing land plants to adapt their life cycle to the changing environment.