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DELLA proteins restrain the cell proliferation and enlargement that characterizes the growth of plant organs. Gibberellin stimulates growth via 26S proteasome-dependent destruction of DELLAs, thus relieving DELLA-mediated growth restraint. Here, we show that the Arabidopsis thaliana sleepy1gar2-1 (sly1gar2-1) mutant allele encodes a mutant subunit (sly1gar2-1) of an SCF(SLY1) E3 ubiquitin ligase complex. SLY1 (the wild-type form) and sly1gar2-1 both confer substrate specificity on this complex via specific binding to the DELLA proteins. However, sly1gar2-1 interacts more strongly with the DELLA target than does SLY1. In addition, the strength of the SCFSLY1-DELLA interaction is increased by target phosphorylation. Growth-promoting DELLA destruction is dependent on SLY1 availability, on the strength of the interaction between SLY1 and the DELLA target, and on promotion of the SCFSLY1-DELLA interaction by DELLA phosphorylation.

Original publication




Journal article


Plant Cell

Publication Date





1406 - 1418


Alkyl and Aryl Transferases, Alleles, Arabidopsis, Arabidopsis Proteins, F-Box Proteins, Genes, Plant, Gibberellins, Macromolecular Substances, Mutation, Phenotype, Phosphorylation, Plant Proteins, Protein Binding, Substrate Specificity, Transcription Factors, Ubiquitin-Protein Ligases