Acts as negative regulator of root hair development redundantly with GIR1 (PubMed:28526410). GIR1 and GIR2 may function as adapter proteins that associate with GL2 and participate in the control of root hair formation (PubMed:28526410). GIR1 and GIR2 may function as adapter proteins that associate with TPL and participate in the repression of root gene expression (PubMed:28526412). Interacts with GL2 (PubMed:28526410). Interacts with TPL (PubMed:28526412). No visible phenotype under normal growth conditions, but the double mutant seedlings gir1 and gir2 exhibit excessive root hair formation.