@article{21490, abstract = {Auxin canalization is a self-organizing process that governs the flexible formation of vasculature by reinforcing the formation of auxin transport channels. A key prerequisite is the feedback between auxin signaling and directional auxin transport, mediated by PIN transporters. Despite the developmental importance of canalization, the molecular components linking auxin perception to the regulation of PIN auxin transporters remain poorly understood. Here, we identify TOW, a novel and essential component of auxin canalization that links intracellular auxin signaling with cell surface auxin perception. TOW is regulated downstream of TIR1/AFB-Aux/IAA-WRKY23 transcriptional auxin signaling. tow mutants exhibit defects in regeneration and de novo vasculature formation, along with impaired formation of polarized, PIN-expressing auxin channels. At the subcellular level, these mutants display disrupted auxin-induced PIN polarization and altered PIN endocytic trafficking dynamics. TOW localizes predominantly to the plasma membrane, where it interacts with receptor-like kinases involved in auxin canalization, including the TMK1 auxin co-receptor and the CAMEL-CANAR complex. TOW promotes PIN interaction with these kinases and stabilizes PINs at the cell surface. Together, our findings identify TOW as a molecular link between intracellular and cell surface auxin signaling mechanisms that converge on PIN trafficking and polarity, providing new insights into how auxin signaling regulates directional auxin transport for the self-organizing formation of vasculature during flexible plant development.}, author = {Li, Mingyue and Rydza, Nikola and Mazur, Ewa and Molnar, Gergely and Nodzyński, Tomasz and Friml, Jiří}, issn = {0960-9822}, journal = {Current Biology}, number = {6}, pages = {1468--1480.e6}, publisher = {Elsevier}, title = {{Receptor-like-kinase-interacting protein TOW stabilizes PIN transporters for auxin canalization}}, doi = {10.1016/j.cub.2026.02.023}, volume = {36}, year = {2026}, } @article{21483, abstract = {Embryogenesis in the model plant Arabidopsis thaliana provides a framework for understanding how cell polarity and patterning coordinate with hormonal signalling to establish the plant body plan. Following fertilisation, the zygote divides asymmetrically to generate apical and basal lineages, establishing the apical–basal axis that defines future shoot and root poles. Genetic and molecular analyses of classical mutants including gnom, monopteros (mp), bodenlos (bdl) and topless revealed that localised auxin biosynthesis, directional transport and downstream transcriptional responses are central to apical–basal axis establishment and organ initiation. The main components of this regulation are polarly localised PIN auxin transporters and downstream modules involving MONOPTEROS and WUSCHEL-RELATED HOMEOBOX transcription factors. Advances in microscopy have transformed the study of Arabidopsis embryogenesis: fluorescence-compatible clearing reagents and three-dimensional reconstructions now permit quantitative analyses of cell geometry, division orientation, and cytoskeletal dynamics. Live ovule imaging setups with confocal laser scanning and multiphoton microscopes enable real-time observation of embryo development, while laser-assisted cell ablation can be used to probe cell-to-cell communication and fate plasticity. Together, these methodological breakthroughs position Arabidopsis embryos as a prime model for dissecting the chemical and biophysical cues that shape plant development.}, author = {Babic, David and Zupunski, Milan and Friml, Jiří}, issn = {1469-8137}, journal = {New Phytologist}, publisher = {Wiley}, title = {{Imaging and genetic toolbox to study Arabidopsis embryogenesis}}, doi = {10.1111/nph.71072}, year = {2026}, } @phdthesis{20964, author = {Vladimirtsev, Dmitrii}, issn = {2791-4585}, pages = {22}, publisher = {Institute of Science and Technology Austria}, title = {{Armadillo repeat only proteins are master regulators of plant cyclic-nucleotide gated channels}}, doi = {10.15479/AT-ISTA-20964}, year = {2026}, } @article{21763, abstract = {Reactive oxygen species (ROS) have been implicated in multiple signaling processes in plants, but the underlying mechanisms and roles remain enigmatic. In this study, we developed a method of live imaging of apoplastic ROS at the root surface. Distinct signals, including auxin, extracellular adenosine triphosphate, and rapid alkalinization factor 1 peptide, induce cytosolic calcium transients and apoplastic ROS bursts. Genetic and optogenetic manipulations of Arabidopsis identified calcium transients as necessary and sufficient for ROS bursts through activation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidases RBOHC and RBOHF. Apoplastic ROS bursts are not required, but they do limit gravity-induced root bending. Root bending is sensed by the stretch-activated calcium channel MCA1, leading to NADPH oxidase activation. The resulting ROS production stiffens cell walls to facilitate soil penetration. Apoplastic ROS thus provides a means to balance tissue flexibility and stiffness to navigate soil.}, author = {Kulich, Ivan and Vladimirtsev, Dmitrii and Randuch, Marek and Gao, Shiqiang and Citterico, Matteo and Konrad, Kai R. and Nagel, Georg and Wrzaczek, Michael and Cascaro, Léa and Vinet, Pauline and Durand, Pauline and Asnacios, Atef and Verma, Lokesh and Bennett, Malcolm J. and Pandey, Bipin K. and Friml, Jiří}, issn = {1095-9203}, journal = {Science}, number = {6795}, pages = {296--300}, publisher = {AAAS}, title = {{Calcium-triggered apoplastic ROS bursts balance gravity and mechanical signals for soil navigation}}, doi = {10.1126/science.adu8197}, volume = {392}, year = {2026}, } @article{18619, abstract = {Brassinosteroids (BRs) are steroidal phytohormones indispensable for plant growth, development, and responses to environmental stresses. The export of bioactive BRs to the apoplast is essential for BR signalling initiation, which requires binding of BR molecule to the extracellular domains of the plasma membrane-localized receptor complex. We have previously shown that the Arabidopsis thaliana ATP-binding cassette (ABC) transporter, ABCB19, functions as a BR exporter, and together with its close homologue, ABCB1, positively regulate BR signalling. Here, we demonstrate that ABCB1 is another BR transporter. The ATP hydrolysis activity of ABCB1 was stimulated by bioactive BRs, and its transport activity was confirmed in proteoliposomes and protoplasts. Structures of ABCB1 in substrate-unbound (apo), brassinolide (BL)-bound, and ATP plus BL-bound states were determined. In the BL-bound structure, BL was bound to the hydrophobic cavity formed by the transmembrane domain, and triggered local conformational changes. Together, our data provide additional insights into the ABC transporter-mediated BR export.}, author = {Wei, H and Zhu, H and Ying, W and Janssens, H and Kvasnica, M and Winne, JM and Gao, Y and Friml, Jiří and Ma, Q and Tan, S and Liu, X and Russinova, E and Sun, L}, issn = {2590-3462}, journal = {Plant Communications}, number = {1}, publisher = {Elsevier}, title = {{Structural insights into brassinosteroid export mediated by the Arabidopsis ABC transporter ABCB1}}, doi = {10.1016/j.xplc.2024.101181}, volume = {6}, year = {2025}, } @article{20029, abstract = {Vacuolar acidification is crucial for the homeostasis of intracellular pH and the recycling of proteins and nutrients in cells, thereby playing important roles in various physiological processes related to vacuolar function. The key factors regulating vacuolar acidification and underlying mechanisms remain unclear. Here, we report that Arabidopsis phospholipase Dζ2 (PLDζ2) promotes the acidification of the vacuolar lumen to stimulate autophagic degradation under phosphorus deficiency. The pldζ2 mutant massively accumulates autophagic structures while exhibiting premature leaf senescence under nutrient starvation. Impaired autophagic flux, lytic vacuole morphology, and lytic degradation in pldζ2 indicate that PLDζ2 regulates autophagy by affecting the vacuolar function. PLDζ2 locates in both tonoplast and cytoplasm. Genetic, structural, and biochemical studies demonstrate that PLDζ2 directly interacts with vacuolar-type ATPase (V-ATPase) subunit D (VATD) to promote vacuolar acidification and autophagy under phosphorus starvation. These findings reveal the importance of V-ATPase and vacuolar pH in autophagic activity and provide clues in elucidating the regulatory mechanism of vacuolar acidification.}, author = {Guan, Bin and Xie, Ke Xuan and Du, Xin Qiao and Bai, Yu Xuan and Hao, Peng Chao and Lin, Wen Hui and Friml, Jiří and Xue, Hong Wei}, issn = {2211-1247}, journal = {Cell Reports}, number = {7}, publisher = {Elsevier}, title = {{Arabidopsis phospholipase Dζ2 facilitates vacuolar acidification and autophagy under phosphorus starvation by interacting with VATD}}, doi = {10.1016/j.celrep.2025.116024}, volume = {44}, year = {2025}, } @article{20031, abstract = {The central vacuole is a multifunctional organelle with the most significant occupancy in a differentiated plant cell. Plants depend on the function of the vacuole for critical development, growth, and environmental responses. As the cell expands, the vacuole changes shape and size, increasing its membrane and luminal content. The set of these events is called the vacuolar configuration process, which has not been well described. Our research highlights the impact of plasma membrane internalization on vacuole morphology during the vacuolar configuration process. We observed a direct correlation between differential endocytosis rates and the enrichment of vacuolar membranous structures. Chemical and genetic interference with clathrin-mediated endocytosis (CME) revealed that it is required for the vacuolar configuration of growing root cells. The contribution of CME to the vacuole configuration process co-occurs with the induction of post-trans-Golgi network (TGN)/early endosome (EE) trafficking with the participation of the Rab GTPases ARA6 and ARA7. Our results show that the CME plays an active role during vacuole configuration, most probably carrying the material that allows the establishment of the vacuole in elongating cells. Since membrane trafficking through the EE/TGN is required to reach the vacuole, additional players must be defined.}, author = {Osorio-Navarro, Claudio and Neira-Valenzuela, Gabriel and Sierra, Paula and Adamowski, Maciek and Toledo, Jorge and Norambuena, Lorena}, issn = {1460-2431}, journal = {Journal of Experimental Botany}, number = {10}, pages = {2700--2714}, publisher = {Oxford University Press}, title = {{The configuration of the vacuole is driven by clathrin-mediated trafficking in root cells of Arabidopsis thaliana}}, doi = {10.1093/jxb/eraf084}, volume = {76}, year = {2025}, } @article{20116, abstract = {Auxin regulates various aspects of plant growth and development by modulating the transcription of target genes through the degradation of auxin/indole-3-acetic acid (Aux/IAA) repressors via the 26S proteasome. Proteasome regulator 1 (PTRE1), a positive regulator of proteasome activity, has been implicated in auxin-mediated proteasome suppression; however, the mechanism by which auxin modulates PTRE1 function remains unclear. Here, we demonstrate that auxin promotes the interaction between germin-like protein 1 (GLP1) and PTRE1, facilitating PTRE1 retention at the plasma membrane. The relocation of PTRE1 results in reduced nuclear 26S proteasome activity, and thus the attenuated Aux/IAA degradation and altered Aux/IAA homeostasis, ultimately resulting in suppressed auxin-mediated transcriptional regulation. Our findings uncover a previously uncharacterized regulatory axis in auxin signaling that controls Aux/IAA protein stability, functioning alongside the TIR1- and TRANSMEMBRANE KINASE 1 (TMK1)-mediated pathways, and highlight the coordination of auxin signaling from the cell surface to the nucleus via auxin-induced PTRE1 relocation, which fine-tunes Aux/IAA protein homeostasis and auxin responses.}, author = {Xu, Faqing and Yu, Yongqiang and Guan, Bin and Xu, Tongda and Xu, Zhihong and Xue, Hongwei}, issn = {2211-1247}, journal = {Cell Reports}, number = {8}, publisher = {Elsevier}, title = {{Germin-like protein 1 interacts with proteasome regulator 1 to regulate auxin signaling by controlling Aux/IAA homeostasis}}, doi = {10.1016/j.celrep.2025.116056}, volume = {44}, year = {2025}, } @article{20635, abstract = {Plants have evolved sophisticated mechanisms to adapt to environmental changes, with root gravitropism playing a pivotal role in nutrient and water acquisition. Our study reveals that SnRK2 kinases (SnRK2.2 and SnRK2.3) are critical regulators of root gravitropism through their direct phosphorylation of the auxin transporter PIN2 at S259. We demonstrate that SnRK2s-mediated phosphorylation modulates both the polar localization and transport activity of PIN2. Importantly, SnRK2s function antagonistically to the AGCVIII kinase PID, which phosphorylates PIN2 at a distinct site (S258), establishing a regulatory balance essential for adaptive root growth. Structural modeling and phosphorylation assays further suggest that SnRK2s-mediated phosphorylation at S259 sterically hinders access of PID to S258, providing a mechanistic basis for their antagonistic relationship. These findings uncover a novel regulatory mechanism, by which plants fine-tune root developmental programs to adapt to environmental stimuli, highlighting the evolutionary significance of multilayered kinase-mediated regulation in plant adaptation.}, author = {Sheng, F and Gao, Y and Wang, Y and Li, Y and Zhang, JA and Zhang, Z and Qin, X and Zhang, S and Song, W and Li, J and Guo, Y and Friml, Jiří and Gong, Z and Zhang, Q and Zhang, J}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences}, number = {39}, pages = {e2512274122}, publisher = {National Academy of Sciences}, title = {{Antagonistic SnRK2 and PID kinases' action on auxin transport-mediated root gravitropism}}, doi = {10.1073/pnas.2512274122}, volume = {122}, year = {2025}, } @article{20636, abstract = {The versatile and pivotal roles of the phytohormone auxin in regulating plant growth and development are typically linked to its directional transport, relying on the polarized PIN-FORMED (PIN) auxin exporters at the plasma membrane (PM). For decades, auxin has been proposed to promote PIN polarization, generating self-regulatory feedback mediating much of plant development, but mechanistic insight into this regulation is lacking. Here, we uncover an auxin-induced protein complex at the PM, containing auxin co-receptors transmembrane kinases (TMKs) and PIN1 auxin exporter, as the core machinery that underlies this feedback regulation. Auxin promotes PIN1 phosphorylation by TMKs, modulating PIN1 polarization and transport activity. We also provide evidence that PIN1-exported extracellular auxin is crucial for TMK activation and cell elongation, thus forming the simplest two-element self-regulatory feedback circuit. Thus, these findings offer direct mechanistic insights into a potential self-organizing circuit for auxin signaling and transport to ensure proper plant development in Arabidopsis.}, author = {Huang, R and Wang, J and Chang, M and Tang, W and Yu, Y and Zhang, Y and Peng, Y and Wang, Y and Guo, Y and Lu, T and Cao, Y and Zhou, Y and Zhang, Q and Huang, Y and Wu, A and Ren, L and Gallei, Michelle C and Dong, J and Chen, H and He, J and Wen, M and Friml, Jiří and Sun, L and Xiong, Y and Yang, Z and Xu, T}, issn = {1878-1551}, journal = {Developmental Cell}, pages = {S1534--5807(25)00569--6}, publisher = {Elsevier}, title = {{TMK-PIN1 drives a short self-organizing circuit for auxin export and signaling in Arabidopsis}}, doi = {10.1016/j.devcel.2025.09.009}, year = {2025}, } @article{20656, abstract = {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.}, author = {Rodriguez Solovey, Lesia and Fiedler, Lukas and Zou, Minxia and Giannini, Caterina and Monzer, Aline and Vladimirtsev, Dmitrii and Randuch, Marek and Yu, Yongfan and Gelová, Zuzana and Verstraeten, Inge and Hajny, Jakub and Chen, Meng and Tan, Shutang and Hörmayer, Lukas and Li, Lanxin and Marques-Bueno, Maria Mar and Quddoos, Zainab and Molnar, Gergely and Kulich, Ivan and Jaillais, Yvon and Friml, Jiří}, issn = {0092-8674}, journal = {Cell}, number = {22}, pages = {6138--6150.e17}, publisher = {Elsevier}, title = {{ABP1/ABL3-TMK1 cell-surface auxin signaling targets PIN2-mediated auxin fluxes for root gravitropism}}, doi = {10.1016/j.cell.2025.08.026}, volume = {188}, year = {2025}, } @article{20663, abstract = {Gravitropism, the patterning of postembryonic growth in relation to the gravity vector, allows plants to optimize the use of limited and nonhomogenous resources in their immediate environment. Since the current model of root gravitropism has not been able to integrate all aspects of the response (perception, response, and behavior), research on gravitropism has been dominated by different theories attempting to conceptualize each aspect individually. In this work, we sought to reevaluate all the main components of the root graviresponse through the lens of angle dependence. We show angle dependence in Cholodny–Went-based auxin asymmetry and growth response, which we tracked back to angle-dependent variation in PIN asymmetry and statolith sedimentation in the columella. Thanks to this approach, we were able to suggest distinct roles for PINs and columella cell tiers, and a potential function for auxin vertical flux through the columella. Our findings provide a unifying framework to further explore the mechanisms that regulate angle-dependent gravitropic response, with major implications of time-dependent features of root graviresponse.}, author = {Roychoudhry, Suruchi and Sageman-Furnas, Katelyn and Taylor, Harry J. and Showpnil, Iftekhar and Wolverton, Chris and Friml, Jiří and Bianco, Marta Del and Kepinski, Stefan}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences}, number = {46}, pages = {e2506400122}, publisher = {National Academy of Sciences}, title = {{Angle dependence as a unifying feature of root graviresponse modules}}, doi = {10.1073/pnas.2506400122}, volume = {122}, year = {2025}, } @article{20725, abstract = {The canonical mechanism by which the phytohormone auxin regulates transcription has been one of the cornerstones of plant signaling. The recent unexpected discovery of cyclic AMP (cAMP) as a second messenger in this pathway has revised its foundations while leaving many open questions and gaps in our understanding; these will be discussed in this forum article.}, author = {Friml, Jiří}, issn = {1878-4372}, journal = {Trends in Plant Science}, pages = {S1360--1385(25)00300--0}, publisher = {Elsevier}, title = {{Role of cAMP in TIR1/AFB auxin signaling: Open issues}}, doi = {10.1016/j.tplants.2025.10.018}, year = {2025}, } @article{20818, abstract = {This study demonstrates that Marchantia non-canonical PINs are predominantly localized to the plasma membrane, with MpPINX and MpPINW exhibiting asymmetric distribution. A newly identified miniW domain within the MpPINW hydrophilic loop governs subcellular trafficking and asymmetric PM localization of non-canonical PINs in Marchantia.}, author = {Tang, Han and Smoljan, Adrijana and Zou, Minxia and Zhang, Yuzhou and Lu, Kuan Ju and Friml, Jiří}, issn = {1365-3040}, journal = {Plant Cell and Environment}, publisher = {Wiley}, title = {{The miniW domain directs polarized membrane localization of non-canonical PINs in Marchantia polymorpha}}, doi = {10.1111/pce.70295}, year = {2025}, } @article{19003, abstract = {Super-resolution methods provide far better spatial resolution than the optical diffraction limit of about half the wavelength of light (∼200-300 nm). Nevertheless, they have yet to attain widespread use in plants, largely due to plants’ challenging optical properties. Expansion microscopy improves effective resolution by isotropically increasing the physical distances between sample structures while preserving relative spatial arrangements and clearing the sample. However, its application to plants has been hindered by the rigid, mechanically cohesive structure of plant tissues. Here, we report on whole-mount expansion microscopy of thale cress (Arabidopsis thaliana) root tissues (PlantEx), achieving a four-fold resolution increase over conventional microscopy. Our results highlight the microtubule cytoskeleton organization and interaction between molecularly defined cellular constituents. Combining PlantEx with stimulated emission depletion (STED) microscopy, we increase nanoscale resolution and visualize the complex organization of subcellular organelles from intact tissues by example of the densely packed COPI-coated vesicles associated with the Golgi apparatus and put these into a cellular structural context. Our results show that expansion microscopy can be applied to increase effective imaging resolution in Arabidopsis root specimens. }, author = {Gallei, Michelle C and Truckenbrodt, Sven M and Kreuzinger, Caroline and Inumella, Syamala and Vistunou, Vitali and Sommer, Christoph M and Tavakoli, Mojtaba and Agudelo Duenas, Nathalie and Vorlaufer, Jakob and Jahr, Wiebke and Randuch, Marek and Johnson, Alexander J and Benková, Eva and Friml, Jiří and Danzl, Johann G}, issn = {1532-298X}, journal = {The Plant Cell}, number = {4}, publisher = {Oxford University Press}, title = {{Super-resolution expansion microscopy in plant roots}}, doi = {10.1093/plcell/koaf006}, volume = {37}, year = {2025}, } @article{19420, abstract = {Auxin and its PIN-FORMED (PIN) exporters are essential for tissue repair and regeneration in flowering plants. To gain insight into the evolution of this mechanism, we investigated their roles in leaves excised from Physcomitrium patens, a bryophyte known for its remarkable cell reprogramming capacity. We used various approaches to manipulate auxin levels, including exogenous application, pharmacological manipulations, and auxin biosynthesis mutants. We observed no significant effect on the rate of cell reprogramming. Rather, our analysis of auxin dynamics revealed a decrease in auxin levels upon excision, which was followed by a local increase before the reprogramming process began. Mutant analysis revealed that PpPINs are required for effective cell reprogramming, and endogenously expressed PpPINA-GFP accumulates polarly at sites that will develop into future filamentous stem cells. In addition, hyperpolarized PpPINA variants carrying mutated phosphorylation sites showed a marked delay in reprogramming, whereas endogenous or nonpolar versions do not have this effect. These results underscore that both the levels and the polarity of PpPINA are important for efficient cell reprogramming. Overall, these findings highlight the pivotal role of PIN polarity in plant regeneration. Furthermore, they suggest that understanding polarity mechanisms could have broader implications for improving regenerative processes across various plant species.}, author = {Tang, Han and Chen, L and Friml, Jiří}, issn = {1471-9053}, journal = {Plant and Cell Physiology}, publisher = {Oxford University Press}, title = {{Auxin fluctuation and PIN polarization in moss leaf cell reprogramming.}}, doi = {10.1093/pcp/pcaf008}, year = {2025}, } @article{19422, abstract = {Nitrogen (N) is an essential macronutrient for plant development and, ultimately, yield. Identifying the genetic components and mechanisms underlying N use efficiency in maize (Zea mays L.) is thus of great importance. Nitrate (NO3−) is the preferred inorganic N source in maize. Here we performed a genome-wide association study of shoot NO3− accumulation in maize seedlings grown under low-NO3− conditions, identifying the ferredoxin family gene ZmFd4 as a major contributor to this trait. ZmFd4 interacts and co-localizes with nitrite reductases (ZmNiRs) in chloroplasts to promote their enzymatic activity. Furthermore, ZmFd4 forms a high-affinity heterodimer with its closest paralogue, ZmFd9, in a NO3−-sensitive manner. Although ZmFd4 exerts similar biochemical functions as ZmFd9, ZmFd4 and ZmFd9 interaction limits their ability to associate with ZmNiRs and stimulate their activity. Knockout lines for ZmFd4 with decreased NO3− contents exhibit more efficient NO3− assimilation, and field experiments show consistently improved N utilization and grain yield under N-deficient conditions. Our work thus provides molecular and mechanistic insights into the natural variation in N utilization, instrumental for genetic improvement of yield in maize and, potentially, in other crops.}, author = {Jia, G and Chen, G and Zhang, Z and Tian, C and Wang, Y and Luo, J and Zhang, K and Zhao, X and Zhao, X and Li, Z and Sun, L and Yang, W and Guo, Y and Friml, Jiří and Gong, Z and Zhang, J}, issn = {2055-0278}, journal = {Nature Plants}, publisher = {Springer Nature}, title = {{Ferredoxin-mediated mechanism for efficient nitrogen utilization in maize}}, doi = {10.1038/s41477-025-01934-w}, volume = {11}, year = {2025}, } @article{19423, abstract = {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.}, author = {Kurtović, K and Vosolsobě, S and Nedvěd, D and Müller, K and Dobrev, PI and Schmidt, V and Piszczek, P and Kuhn, A and Smoljan, Adrijana and Fisher, TJ and Weijers, D and Friml, Jiří and Bowman, JL and Petrášek, J}, issn = {1469-8137}, journal = {New Phytologist}, number = {3}, pages = {1066--1083}, publisher = {Wiley}, title = {{The role of indole-3-acetic acid and characterization of PIN transporters in complex streptophyte alga Chara braunii}}, doi = {10.1111/nph.70019}, volume = {246}, year = {2025}, } @article{19601, abstract = {In land plants, the signalling molecule auxin profoundly controls growth and development, chiefly through a transcriptional response system. The auxin response is mediated by modulating the activity of DNA-binding auxin response factor (ARF) proteins. The concentrations and stoichiometry of the competing A- and B-class ARFs define cells’ capacity for auxin response. In the minimal auxin response system of the liverwort Marchantia polymorpha, both A- and B-ARFs are unstable, but the underlying mechanisms, developmental relevance and evolutionary history of this instability are unknown. Here we identify a minimal motif that is necessary for MpARF2 (B-class) degradation and show that it is critical for development and the auxin response. Through comparative analysis and motif swaps among all ARF classes in extant algae and land plants, we infer that the emergence of ARF instability probably occurred in the ancestor of the A- and B-ARF clades and, therefore, preceded or coincided with the origin of the auxin response system.}, author = {De Roij, Martijn and Hernández García, Jorge and Das, Shubhajit and Borst, Jan Willem and Weijers, Dolf}, issn = {2055-0278}, journal = {Nature Plants}, pages = {717--724}, publisher = {Springer Nature}, title = {{ARF degradation defines a deeply conserved step in auxin response}}, doi = {10.1038/s41477-025-01975-1}, volume = {11}, year = {2025}, } @article{19736, abstract = {The phytohormone auxin is a major signal coordinating growth and development in plants. The variety of its effects arises from its ability to form local auxin maxima and gradients within tissues, generated through directional cell-to-cell transport and elaborate metabolic control. These auxin distribution patterns instruct cells in a context-dependent manner to undergo predefined developmental transitions. In this Review, we discuss advances in auxin action at the level of homeostasis and signalling. We highlight key insights into the structural basis of PIN-mediated intercellular auxin transport and explore two novel non-transcriptional auxin signalling mechanisms: one involving intracellular Ca2+ transients and another involving cell-surface auxin perception that mediates global, ultrafast phosphorylation. Furthermore, we examine emerging evidence indicating the involvement of cyclic adenosine monophosphate as a second messenger in the transcriptional auxin response. Together, these recent developments in auxin research have profoundly deepened our understanding of the complex and diverse activities of auxin in plant growth and development.}, author = {Vanneste, Steffen and Pei, Yuanrong and Friml, Jiří}, issn = {1471-0080}, journal = {Nature Reviews Molecular Cell Biology}, publisher = {Springer Nature}, title = {{Mechanisms of auxin action in plant growth and development}}, doi = {10.1038/s41580-025-00851-2}, year = {2025}, }