article published yes K Kurtović author S Vosolsobě author D Nedvěd author K Müller author PI Dobrev author V Schmidt author P Piszczek author A Kuhn author Adrijana Smoljan author cced8a85-223e-11ed-af04-b0596c55053b TJ Fisher author D Weijers author Jiří Friml author 4159519E-F248-11E8-B48F-1D18A9856A870000-0002-8302-7596 JL Bowman author J Petrášek author JiFr department Peptide receptors for auxin canalization in Arabidopsis project Auxin, indole-3-acetic acid (IAA), is a key phytohormone with diverse morphogenic roles in land plants, but its function and transport mechanisms in algae remain poorly understood. We therefore aimed to explore the role of IAA in a complex, streptophyte algae Chara braunii. Here, we described novel responses of C. braunii to IAA and characterized two homologs of PIN auxin efflux carriers: CbPINa and CbPINc. We determined their localization in C. braunii using epitope-specific antibodies and tested their function in heterologous land plant models. Further, using phosphoproteomic analysis, we identified IAA-induced phosphorylation events. The thallus regeneration assay showed that IAA promotes thallus elongation and side branch development. Immunolocalization of CbPINa and CbPINc confirmed their presence on the plasma membrane of vegetative and generative cells of C. braunii. However, functional assays in tobacco BY-2 cells demonstrated that CbPINa affects auxin transport, whereas CbPINc does not. The IAA is effective in the acceleration of cytoplasmic streaming and the phosphorylation of evolutionary conserved targets such as homolog of RAF-like kinase. These findings suggest that, although canonical PIN-mediated auxin transport mechanisms might not be fully conserved in Chara, IAA is involved in morphogenesis and fast signaling processes. https://research-explorer.ista.ac.at/download/19423/19571/2025_NewPhytologist_Kurtovic.pdf application/pdfno Wiley2025 eng 1469-8137 40047465 00143871160000110.1111/nph.70019 24631066-1083 Kurtović, K., Vosolsobě, S., Nedvěd, D., Müller, K., Dobrev, P., Schmidt, V., … Petrášek, J. (2025). The role of indole-3-acetic acid and characterization of PIN transporters in complex streptophyte alga Chara braunii. <i>New Phytologist</i>. Wiley. <a href="https://doi.org/10.1111/nph.70019">https://doi.org/10.1111/nph.70019</a> K. Kurtović <i>et al.</i>, “The role of indole-3-acetic acid and characterization of PIN transporters in complex streptophyte alga Chara braunii,” <i>New Phytologist</i>, vol. 246, no. 3. Wiley, pp. 1066–1083, 2025. Kurtović K, Vosolsobě S, Nedvěd D, et al. The role of indole-3-acetic acid and characterization of PIN transporters in complex streptophyte alga Chara braunii. <i>New Phytologist</i>. 2025;246(3):1066-1083. doi:<a href="https://doi.org/10.1111/nph.70019">10.1111/nph.70019</a> Kurtović, K., et al. “The Role of Indole-3-Acetic Acid and Characterization of PIN Transporters in Complex Streptophyte Alga Chara Braunii.” <i>New Phytologist</i>, vol. 246, no. 3, Wiley, 2025, pp. 1066–83, doi:<a href="https://doi.org/10.1111/nph.70019">10.1111/nph.70019</a>. Kurtović, K, S Vosolsobě, D Nedvěd, K Müller, PI Dobrev, V Schmidt, P Piszczek, et al. “The Role of Indole-3-Acetic Acid and Characterization of PIN Transporters in Complex Streptophyte Alga Chara Braunii.” <i>New Phytologist</i>. Wiley, 2025. <a href="https://doi.org/10.1111/nph.70019">https://doi.org/10.1111/nph.70019</a>. K. Kurtović, S. Vosolsobě, D. Nedvěd, K. Müller, P. Dobrev, V. Schmidt, P. Piszczek, A. Kuhn, A. Smoljan, T. Fisher, D. Weijers, J. Friml, J. Bowman, J. Petrášek, New Phytologist 246 (2025) 1066–1083. Kurtović K, Vosolsobě S, Nedvěd D, Müller K, Dobrev P, Schmidt V, Piszczek P, Kuhn A, Smoljan A, Fisher T, Weijers D, Friml J, Bowman J, Petrášek J. 2025. The role of indole-3-acetic acid and characterization of PIN transporters in complex streptophyte alga Chara braunii. New Phytologist. 246(3), 1066–1083. 194232025-03-19T09:45:11Z2025-09-30T11:11:18Z