Provide a mechanistic link between auxin and plasma membrane H(+)-ATPases (PM H(+)-ATPases, e.g. AHA1 and AHA2), and triggers PM H(+)-ATPases activity by promoting phosphorylation of their C-terminal autoinhibitory domain as a result of PP2C-D subfamily of type 2C phosphatases inhibition, thus leading to the acidification of the apoplast and the facilitation of solutes and water uptake to drive cell expansion (By similarity). Triggers plant growth probably by promoting cell elongation (By similarity). Regulates branch angles and bending (By similarity). Effector of hormonal and environmental signals in plant growth (Probable). Interacts with BZR1. Expressed in cotyledons, leaves, flowers and siliques. In flowers, present in stamen, petals and stigma. Up-regulated by brassinosteroids and gibberellins (PubMed:23020777, PubMed:29258424). Up-regulated by auxin (PubMed:16901781, PubMed:16371470, PubMed:29258424). Up-regulated by phototropism and gravitropism in the region of the hypocotyl farthest form the incident stimulation (PubMed:16371470). Transcriptionally regulated by ARF7 (PubMed:16371470). Down-regulated by abscisic acid and methyl jasmonate (PubMed:23020777). Induced by zeatin (PubMed:29258424). Belongs to the ARG7 family.