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 (PubMed:24858935). Plays a role in the regulation of cell expansion, root meristem patterning and auxin transport (By similarity). Interacts with and inhibits PP2C-D subfamily of type 2C phosphatases such as PP2C67/PP2C-D1. Belongs to the ARG7 family.