thesis published Aline Monzer author 2DB5D88C-D7B3-11E9-B8FD-7907E6697425 Jiří Friml supervisor GradSch department JiFr department Plant growth and development rely significantly on phytohormones, with auxin serving as a master regulator, orchestrating processes from embryogenesis to organogenesis, vascular patterning, and environmental adaptation. Since its conceptual proposition by Charles Darwin in 1880 as an endogenous chemical signal influencing phototropism in grass, auxin has captivated scientists seeking to understand how such a small molecule exerts a profound influence on plant development. One particularly fascinating aspect of auxin function is its ability to self-organize its transport. Through a feedback mechanism between auxin perception and directional transport—primarily mediated by PIN auxin transporters—auxin establishes narrow transport channels. This phenomenon, known as auxin canalization, is fundamental to vascular formation, regeneration, and other key developmental processes. Despite advances in our understanding, driven by experimental studies and computational models, auxin canalization remains an enigma, with many unanswered questions. Like other hormones, auxin functions through intricate signaling pathways. It operates through at least two distinct signaling mechanisms: the well-characterized canonical pathway and the less understood non-canonical pathway. While significant progress has been made in elucidating the canonical pathway, the non-canonical mechanisms remain less defined and require further investigation. In this study, we revisit the non-canonical auxin signaling pathway mediated by the cell-surface complex Auxin Binding Protein 1-Transmembrane Kinase 1 (ABP1-TMK1), with a particular focus on its downstream phosphorylation events. We reveal that this auxin-mediated phosphorylation is conserved across the green lineage, underscoring its fundamental role in plant development. We explore key phosphorylation targets, particularly PIN2, which is essential for root gravitropism. To further understand TMK1’s role in diverse developmental processes, we identified and investigated its interactors as potential co-receptors or regulatory components within its signaling network. Given the previously established role of ABP1-TMK1 in auxin canalization, we sought to further investigate this process and identified several TMK1 interactors also involved in this intricate mechanism. These findings provide new insights into the complex regulation of auxin canalization, highlighting a broader and more interconnected signaling framework than previously understood. https://research-explorer.ista.ac.at/download/19395/19396/Final Thesis Aline Monzer.pdf application/pdfno https://research-explorer.ista.ac.at/download/19395/19397/Thesis Aline.docx application/vnd.openxmlformats-officedocument.wordprocessingml.document Institute of Science and Technology Austria2025 eng 2663-337X10.15479/AT-ISTA-19395 160 https://research-explorer.ista.ac.at/record/12291 https://research-explorer.ista.ac.at/record/14826 https://research-explorer.ista.ac.at/record/19399 https://research-explorer.ista.ac.at/record/19398 A. Monzer, Cell-Surface Auxin Signaling: Linking Molecular Pathways to Plant Development, Institute of Science and Technology Austria, 2025. A. Monzer, “Cell-Surface Auxin Signaling: Linking molecular pathways to plant development,” Institute of Science and Technology Austria, 2025. Monzer A. Cell-Surface Auxin Signaling: Linking molecular pathways to plant development. 2025. doi:<a href="https://doi.org/10.15479/AT-ISTA-19395">10.15479/AT-ISTA-19395</a> Monzer A. 2025. Cell-Surface Auxin Signaling: Linking molecular pathways to plant development. Institute of Science and Technology Austria. Monzer, Aline. “Cell-Surface Auxin Signaling: Linking Molecular Pathways to Plant Development.” Institute of Science and Technology Austria, 2025. <a href="https://doi.org/10.15479/AT-ISTA-19395">https://doi.org/10.15479/AT-ISTA-19395</a>. Monzer, A. (2025). <i>Cell-Surface Auxin Signaling: Linking molecular pathways to plant development</i>. Institute of Science and Technology Austria. <a href="https://doi.org/10.15479/AT-ISTA-19395">https://doi.org/10.15479/AT-ISTA-19395</a> Monzer, Aline. <i>Cell-Surface Auxin Signaling: Linking Molecular Pathways to Plant Development</i>. Institute of Science and Technology Austria, 2025, doi:<a href="https://doi.org/10.15479/AT-ISTA-19395">10.15479/AT-ISTA-19395</a>. 193952025-03-12T14:25:42Z2026-07-06T12:52:09Z