Transcription factor which acts as positive regulator of drought stress tolerance. Can transactivate CIPK3, NCED3 and ERECTA (PubMed:18451323). Transactivates several cell-wall-loosening protein genes by directly binding to HD motifs in their promoters. These target genes play important roles in coordinating cell-wall extensibility with root development and growth (PubMed:24821957). Transactivates CYP74A/AOS, AOC3, OPR3 and 4CLL5/OPCL1 genes by directly binding to HD motifs in their promoters. These target genes are involved in jasmonate (JA) biosynthesis, and JA signaling affects root architecture by activating auxin signaling, which promotes lateral root formation (PubMed:25752924). Acts as negative regulator of trichome branching (PubMed:16778018, PubMed:24824485). Required for the establishment of giant cell identity on the abaxial side of sepals (PubMed:23095885). Seems to promote cell differentiation (PubMed:25564655). May regulate cell differentiation and proliferation during root and shoot meristem development (PubMed:25564655). Interacts with BBM. Expressed in apical meristems and young epidermal tissue including trichomes and stipules. Expressed in lateral root tips, the L1 layer of apical inflorescence meristems and early flower primordia, carpel and petal epidermis, stigma papillae, ovule primordia, nucellus and embryo. During embryo development, expressed in all cells at the 4- and 16-cell embryo stages (PubMed:25564655). Expression is restricted to the protoderm from the globular stage onward (PubMed:25564655). In primary and lateral roots, observed in the epidermis, the outer layer of columella cells and lateral root cap (PubMed:25564655). Plants show excess branching of trichomes (PubMed:16778018, PubMed:24824485). In plants missing HDG3, HDG7, HDG11, PDF2 and ATML1, increased cell division leading to cell overproliferation (PubMed:25564655). The gain-of-function mutant edt1 (T-DNA tagging) exhibit enhanced drought tolerance, increased root system development, reduced leaf stomatal density, increased levels of abscisic acid and prolamine, increased resistance to oxidative stress and high levels of superoxide dismutase. Belongs to the HD-ZIP homeobox family. Class IV subfamily.