Regulates an ATP-dependent metal transporter (e.g. manganese transporter). Probably involved in the metabolism of auxin conjugates such as indole-3-acetic acid-leucine (IAA-Leu) and IAA-Phe. Required for root development. Recessive resistance to auxin conjugates indole-3-acetic acid-leucine (IAA-Leu) and IAA-Phe, but normal sensitivity to free IAA. Defective in lateral root formation and primary root elongation. Resistant to manganese- and cobalt-mediated inhibition of root elongation probably due to an enhanced ATP-dependent manganese transport.