Phytohormone auxin and its directional transport mediate much of the remarkably plastic development of higher plants. Positive feedback between auxin signaling and transport is a prerequisite for (1) self-organizing processes, including vascular tissue formation, and (2) directional growth responses such as gravitropism. Here, we identify a mechanism by which auxin signaling directly targets PIN auxin transporters. Via the cell-surface AUXIN-BINDING PROTEIN1 (ABP1)-TRANSMEMBRANE KINASE 1 (TMK1) receptor module, auxin rapidly induces phosphorylation and thus stabilization of PIN2. Following gravistimulation, initial auxin asymmetry activates autophosphorylation of the TMK1 kinase. This induces TMK1 interaction with and phosphorylation of PIN2, stabilizing PIN2 at the lower root side, thus reinforcing asymmetric auxin flow for root bending. Upstream of TMK1 in this regulation, ABP1 acts redundantly with the root-expressed ABP1-LIKE 3 (ABL3) auxin receptor. Such positive feedback between cell-surface auxin signaling and PIN-mediated polar auxin transport is fundamental for robust root gravitropism and presumably for other self-organizing developmental phenomena.

Institute of Science and Technology Austria Am Campus 1 3400 Klosterneuburg Austria

Institute of Science and Technology Austria Am Campus 1 3400 Klosterneuburg Austria; Laboratory of Growth Regulators The Czech Academy of Sciences Institute of Experimental Botany and Palacký University Šlechtitelů 27 77900 Olomouc Czech Republic

Institute of Science and Technology Austria Am Campus 1 3400 Klosterneuburg Austria; MOE Key Laboratory for Cellular Dynamics Center for Advanced Interdisciplinary Science and Biomedicine of IHM Hefei National Laboratory for Physical Sciences at the Microscale Division of Life Sciences and Medicine University of Science and Technology of China Hefei 230027 China

Laboratoire Reproduction et Développement des Plantes Université de Lyon ENS de Lyon UCB Lyon 1 CNRS INRAe 69342 Lyon France

MOE Key Laboratory for Cellular Dynamics Center for Advanced Interdisciplinary Science and Biomedicine of IHM Hefei National Laboratory for Physical Sciences at the Microscale Division of Life Sciences and Medicine University of Science and Technology of China Hefei 230027 China

Citace poskytuje Crossref.org

A novel mechanism of auxin habituation: upregulation of auxin receptor TRANSPORT INHIBITOR RESPONSE 1 allows cell proliferation independent of external auxin