preprint draft Lesia Rodriguez Solovey author 3922B506-F248-11E8-B48F-1D18A9856A870000-0002-7244-7237 Lukas Fiedler author 7c417475-8972-11ed-ae7b-8b674ca26986 Minxia Zou author 5c243f41-03f3-11ec-841c-96faf48a7ef9 Caterina Giannini author e3fdddd5-f6e0-11ea-865d-ca99ee6367f4 Aline Monzer author 2DB5D88C-D7B3-11E9-B8FD-7907E6697425 Dmitrii Vladimirtsev author 60466724-5355-11ee-ae5a-fa55e8f99c3d Marek Randuch author 6ac4636d-15b2-11ec-abd3-fb8df79972ae Yongfan Yu author Zuzana Gelová author 0AE74790-0E0B-11E9-ABC7-1ACFE56974250000-0003-4783-1752 Inge Verstraeten author 362BF7FE-F248-11E8-B48F-1D18A9856A870000-0001-7241-2328 Jakub Hajny author 4800CC20-F248-11E8-B48F-1D18A9856A870000-0003-2140-7195 Meng Chen author Shutang Tan author 2DE75584-F248-11E8-B48F-1D18A9856A870000-0002-0471-8285 Lukas Hörmayer author 2EEE7A2A-F248-11E8-B48F-1D18A9856A870000-0001-8295-2926 Lanxin Li author 367EF8FA-F248-11E8-B48F-1D18A9856A870000-0002-5607-272X Maria Mar Marques-Bueno author Zainab Quddoos author 32ff3c64-04a0-11f0-a50f-d0c45bfac466 Gergely Molnar author 34F1AF46-F248-11E8-B48F-1D18A9856A87 Tongda Xu author Ivan Kulich author 57a1567c-8314-11eb-9063-c9ddc3451a54 Yvon Jaillais author Jiří Friml author 4159519E-F248-11E8-B48F-1D18A9856A870000-0002-8302-7596 JiFr department XiFe department Tracing Evolution of Auxin Transport and Polarity in Plants project Molecular mechanisms of endocytic cargo recognition in plants project International IST Postdoc Fellowship Programme project Cell surface receptor complexes for auxin signaling in plants project 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 key prerequisite for (i) self-organizing processes including vascular tissue formation and (ii) directional growth responses such as gravitropism. Here we identify a mechanism, by which auxin signaling directly targets PIN auxin transporters. Via the cell-surface ABP1-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 auxin receptor ABL3. Such positive feedback between cell-surface auxin signaling and PIN-mediated polar auxin transport is fundamental for robust root gravitropism and presumably also for other self-organizing developmental phenomena. 2025 eng 10.1101/2022.11.30.518503 https://research-explorer.ista.ac.at/record/20656 https://research-explorer.ista.ac.at/record/19395 https://research-explorer.ista.ac.at/record/20364 Rodriguez Solovey, Lesia, et al. “ABP1/ABL3-TMK1 Cell-Surface Auxin Signaling Directly Targets PIN2-Mediated Auxin Fluxes for Root Gravitropism.” <i>BioRxiv</i>, doi:<a href="https://doi.org/10.1101/2022.11.30.518503">10.1101/2022.11.30.518503</a>. Rodriguez Solovey, L., Fiedler, L., Zou, M., Giannini, C., Monzer, A., Vladimirtsev, D., … Friml, J. (n.d.). ABP1/ABL3-TMK1 cell-surface auxin signaling directly targets PIN2-mediated auxin fluxes for root gravitropism. <i>bioRxiv</i>. <a href="https://doi.org/10.1101/2022.11.30.518503">https://doi.org/10.1101/2022.11.30.518503</a> Rodriguez Solovey L, Fiedler L, Zou M, Giannini C, Monzer A, Vladimirtsev D, Randuch M, Yu Y, Gelová Z, Verstraeten I, Hajny J, Chen M, Tan S, Hörmayer L, Li L, Marques-Bueno MM, Quddoos Z, Molnar G, Xu T, Kulich I, Jaillais Y, Friml J. ABP1/ABL3-TMK1 cell-surface auxin signaling directly targets PIN2-mediated auxin fluxes for root gravitropism. bioRxiv, <a href="https://doi.org/10.1101/2022.11.30.518503">10.1101/2022.11.30.518503</a>. L. Rodriguez Solovey <i>et al.</i>, “ABP1/ABL3-TMK1 cell-surface auxin signaling directly targets PIN2-mediated auxin fluxes for root gravitropism,” <i>bioRxiv</i>. . Rodriguez Solovey, Lesia, Lukas Fiedler, Minxia Zou, Caterina Giannini, Aline Monzer, Dmitrii Vladimirtsev, Marek Randuch, et al. “ABP1/ABL3-TMK1 Cell-Surface Auxin Signaling Directly Targets PIN2-Mediated Auxin Fluxes for Root Gravitropism.” <i>BioRxiv</i>, n.d. <a href="https://doi.org/10.1101/2022.11.30.518503">https://doi.org/10.1101/2022.11.30.518503</a>. Rodriguez Solovey L, Fiedler L, Zou M, et al. ABP1/ABL3-TMK1 cell-surface auxin signaling directly targets PIN2-mediated auxin fluxes for root gravitropism. <i>bioRxiv</i>. doi:<a href="https://doi.org/10.1101/2022.11.30.518503">10.1101/2022.11.30.518503</a> L. Rodriguez Solovey, L. Fiedler, M. Zou, C. Giannini, A. Monzer, D. Vladimirtsev, M. Randuch, Y. Yu, Z. Gelová, I. Verstraeten, J. Hajny, M. Chen, S. Tan, L. Hörmayer, L. Li, M.M. Marques-Bueno, Z. Quddoos, G. Molnar, T. Xu, I. Kulich, Y. Jaillais, J. Friml, BioRxiv (n.d.). 193992025-03-13T08:36:48Z2026-10-16T22:31:29Z