The promiscuity of DELLA proteins was acquired during early land plant evolution

Abstract

DELLA proteins are land-plant speci%c transcriptional regulators that transduce environmental information to multiple processes throughout a plant’s life. The molecular basis for this critical function in angiosperms has been linked to the regulation of DELLA stability by gibberellins and to the capacity of DELLA proteins to interact with hundreds of transcription factors (TFs). However, it is not clear whether this promiscuity is an ancestral property of DELLA proteins or it is associated with their role in gibberellin signaling. We have found that representative DELLAs from the main plant lineages display a conserved ability to interact with multiple TFs. However, we have detected an extensive diversi%cation in the output target genes and biological processes regulated by these interactions, by comparing the DELLA-dependent transcriptomes across different land-plant lineages. We propose that promiscuity was already encoded in the ancestral DELLA protein, and that this molecular property has been largely maintained, while the lineage-dependent diversi%cation of DELLA- dependent biological functions mostly re#ects the functional evolution of their interacting partners.