Transcriptional repressor involved in the regulation of gibberrelin (GA) signaling. Binds to the 5'-GATC-3' motif of HD16/EL1 promoter. Functions as a positive regulator of GA signaling by suppressing the expression of HD16/EL1, a negative regulator of GA signaling. Expressed in roots, leaves, stems, panicle and seeds. Expressed in the outer layers of globular embryos. Induced by gibberellin. Plants over-expressing HAZ1 show increased length of the uppermost internode and panicle, due to enhanced gibberellin signaling. Belongs to the PHD-associated homeobox family.