Major facilitator superfamily (MFS) transporter probably involved in 2,4-dichlorophenoxyacetic acid (2,4-D) export (PubMed:19440702). K(+) may be the physiological substrate of the transporter (PubMed:23524662). Modulates root auxin-related processes. Involved in auxin efflux and acts as a positive regulator of shootward transport at the root apex. May mediate proton efflux from the vacuolar compartment. Mediates drought stress tolerance by regulating stomatal closure. Predominantly expressed in roots and stomatal guard cells. Detected in anther stamen filaments and shoot apical meristem. In the mature portion of roots, restricted to the cortex. At the root tip, highly expressed in both the cortical and epidermal cell layers of the apical meristem and the transition zone, while absent from the quiescent center or the columella cells. Not detected in lateral root primordia. Expressed throughout development. By 2,4-D treatment. No visible phenotype when grown under normal conditions (PubMed:23524662). No visible phenotype when grown in presence of zinc (PubMed:17277087). Hypersensitivity to drought stress and auxin-related defects (PubMed:23524662). Heterologous expression of ZIFL1 in yeast leads to increased resistance to 2,4-dichlorophenoxyacetic acid (2,4-D), indole-3-acetic acid (IAA), aluminum and thallium. Not involved in zinc stress resistance. Belongs to the major facilitator superfamily. Truncated N-terminus.