DELLArepressors

DELLArepressors are a group of plant transcriptional regulators that function as negative regulators of gibberellin (GA) signaling, thereby restricting plant growth. They are named for the conserved DELLA motif found in their N-terminal region, a key feature that mediates their GA-dependent control.

Mechanistically, DELLA repressors accumulate in conditions of low GA and inhibit growth by interacting with a range of transcription factors such as PIFs and BZR1, suppressing GA-responsive gene expression. When GA levels rise, the hormone binds to its receptor GID1, forming a GA-GID1-DELLA complex that targets the repressors for ubiquitination and proteasomal degradation via the SCFSLY1/GID2 E3 ligase. This degradation relieves repression and enables GA responses, including stem elongation and seed germination.

DELLArepressors belong to the GRAS family of transcription factors and typically contain an N-terminal DELLA motif and a TVHYNP motif, followed by a C-terminal GRAS domain essential for their function. The DELLA module is crucial for GA-induced degradation, while the GRAS domain mediates interactions with other proteins.

Biologically, DELLA repressors influence various growth processes such as seed germination, shoot and root growth, flowering time, and fertility. They also participate in hormonal cross-talk, integrating signals from auxin, brassinosteroids, and abscisic acid, as well as environmental cues, to modulate development and stress responses.

Evolutionarily, DELLA genes are present across land plants and often exist as a small gene family with species-specific numbers. In agriculture, manipulating DELArepressor activity has been explored to adjust plant height, improve lodging resistance, and tune stress tolerance, illustrating their importance in crop biology and breeding.