Probable transcriptional regulator that acts as a repressor of the gibberellin (GA) signaling pathway (By similarity). Probably acts by participating in large multiprotein complexes that repress transcription of GA-inducible genes (By similarity). Upon GA application, it is degraded by the proteasome, allowing the GA signaling pathway (By similarity). Together with DELLA2, required to enable arbuscule development during arbuscular mycorrhizal (AM) symbiosis with AM fungi (e.g. Glomus versiforme) via the regulation of RAM1 which, in turn, regulates various AM genes (e.g. NSP1, NSP2, PT4, LEC5, RAM2, EXO70I, STR and RAD1) (PubMed:26511916, PubMed:24297892). May be a homodimer. Strongly expressed in the vascular tissue and endodermis but barely in the inner cortical cells where arbuscule are formed during arbuscular mycorrhizal (AM) symbiosis. Accumulates upon phosphate (Pi) deprivation (PubMed:24297892). Expressed during arbuscular mycorrhizal (AM) symbiosis with AM fungi (e.g. Glomus versiforme) (PubMed:24297892). The DELLA motif is required for its GA-induced degradation. Ubiquitinated. Upon GA application it is ubiquitinated, leading to its subsequent degradation. The double mutant della1/della2 exhibit slender shoots, early flowering and reduced root fresh weight (PubMed:24297892). Impaired arbuscule formation during arbuscular mycorrhizal (AM) symbiosis with AM fungi (e.g. Glomus versiforme) in plant missing both DELLA1 and DELLA2 associated with a reduced expression of AM genes (e.g. NSP1, NSP2, PT4 and LEC5); these phenotypes are phenocopied by treatment with gibberellic acid (GA) (PubMed:24297892). Belongs to the GRAS family. DELLA subfamily. Truncated N-terminus.