@article{12543, abstract = {Treating sick group members is a hallmark of collective disease defence in vertebrates and invertebrates alike. Despite substantial effects on pathogen fitness and epidemiology, it is still largely unknown how pathogens react to the selection pressure imposed by care intervention. Using social insects and pathogenic fungi, we here performed a serial passage experiment in the presence or absence of colony members, which provide social immunity by grooming off infectious spores from exposed individuals. We found specific effects on pathogen diversity, virulence and transmission. Under selection of social immunity, pathogens invested into higher spore production, but spores were less virulent. Notably, they also elicited a lower grooming response in colony members, compared with spores from the individual host selection lines. Chemical spore analysis suggested that the spores from social selection lines escaped the caregivers’ detection by containing lower levels of ergosterol, a key fungal membrane component. Experimental application of chemically pure ergosterol indeed induced sanitary grooming, supporting its role as a microbe-associated cue triggering host social immunity against fungal pathogens. By reducing this detection cue, pathogens were able to evade the otherwise very effective collective disease defences of their social hosts.}, author = {Stock, Miriam and Milutinovic, Barbara and Hönigsberger, Michaela and Grasse, Anna V and Wiesenhofer, Florian and Kampleitner, Niklas and Narasimhan, Madhumitha and Schmitt, Thomas and Cremer, Sylvia}, issn = {2397-334X}, journal = {Nature Ecology and Evolution}, pages = {450--460}, publisher = {Springer Nature}, title = {{Pathogen evasion of social immunity}}, doi = {10.1038/s41559-023-01981-6}, volume = {7}, year = {2023}, } @article{14313, abstract = {To respond to auxin, the chief orchestrator of their multicellularity, plants evolved multiple receptor systems and signal transduction cascades. Despite decades of research, however, we are still lacking a satisfactory synthesis of various auxin signaling mechanisms. The chief discrepancy and historical controversy of the field is that of rapid and slow auxin effects on plant physiology and development. How is it possible that ions begin to trickle across the plasma membrane as soon as auxin enters the cell, even though the best-characterized transcriptional auxin pathway can take effect only after tens of minutes? Recently, unexpected progress has been made in understanding this and other unknowns of auxin signaling. We provide a perspective on these exciting developments and concepts whose general applicability might have ramifications beyond auxin signaling.}, author = {Fiedler, Lukas and Friml, Jiří}, issn = {1369-5266}, journal = {Current Opinion in Plant Biology}, number = {10}, publisher = {Elsevier}, title = {{Rapid auxin signaling: Unknowns old and new}}, doi = {10.1016/j.pbi.2023.102443}, volume = {75}, year = {2023}, } @unpublished{14591, abstract = {Clathrin-mediated endocytosis (CME) is vital for the regulation of plant growth and development by controlling plasma membrane protein composition and cargo uptake. CME relies on the precise recruitment of regulators for vesicle maturation and release. Homologues of components of mammalian vesicle scission are strong candidates to be part of the scissin machinery in plants, but the precise roles of these proteins in this process is not fully understood. Here, we characterised the roles of Plant Dynamin-Related Proteins 2 (DRP2s) and SH3-domain containing protein 2 (SH3P2), the plant homologue to Dynamins’ recruiters, like Endophilin and Amphiphysin, in the CME by combining high-resolution imaging of endocytic events in vivo and characterisation of the purified proteins in vitro. Although DRP2s and SH3P2 arrive similarly late during CME and physically interact, genetic analysis of the Dsh3p1,2,3 triple-mutant and complementation assays with non-SH3P2-interacting DRP2 variants suggests that SH3P2 does not directly recruit DRP2s to the site of endocytosis. These observations imply that despite the presence of many well-conserved endocytic components, plants have acquired a distinct mechanism for CME. One Sentence Summary In contrast to predictions based on mammalian systems, plant Dynamin-related proteins 2 are recruited to the site of Clathrin-mediated endocytosis independently of BAR-SH3 proteins.}, author = {Gnyliukh, Nataliia and Johnson, Alexander J and Nagel, Marie-Kristin and Monzer, Aline and Hlavata, Annamaria and Isono, Erika and Loose, Martin and Friml, Jiří}, booktitle = {bioRxiv}, title = {{Role of dynamin-related proteins 2 and SH3P2 in clathrin-mediated endocytosis in plants}}, doi = {10.1101/2023.10.09.561523}, year = {2023}, } @article{14339, abstract = {Lateral roots are typically maintained at non-vertical angles with respect to gravity. These gravitropic setpoint angles are intriguing because their maintenance requires that roots are able to effect growth response both with and against the gravity vector, a phenomenon previously attributed to gravitropism acting against an antigravitropic offset mechanism. Here we show how the components mediating gravitropism in the vertical primary root—PINs and phosphatases acting upon them—are reconfigured in their regulation such that lateral root growth at a range of angles can be maintained. We show that the ability of Arabidopsis lateral roots to bend both downward and upward requires the generation of auxin asymmetries and is driven by angle-dependent variation in downward gravitropic auxin flux acting against angle-independent upward, antigravitropic flux. Further, we demonstrate a symmetry in auxin distribution in lateral roots at gravitropic setpoint angle that can be traced back to a net, balanced polarization of PIN3 and PIN7 auxin transporters in the columella. These auxin fluxes are shifted by altering PIN protein phosphoregulation in the columella, either by introducing PIN3 phosphovariant versions or via manipulation of levels of the phosphatase subunit PP2A/RCN1. Finally, we show that auxin, in addition to driving lateral root directional growth, acts within the lateral root columella to induce more vertical growth by increasing RCN1 levels, causing a downward shift in PIN3 localization, thereby diminishing the magnitude of the upward, antigravitropic auxin flux.}, author = {Roychoudhry, S and Sageman-Furnas, K and Wolverton, C and Grones, Peter and Tan, Shutang and Molnar, Gergely and De Angelis, M and Goodman, HL and Capstaff, N and JPB, Lloyd and Mullen, J and Hangarter, R and Friml, Jiří and Kepinski, S}, issn = {2055-0278}, journal = {Nature Plants}, pages = {1500--1513}, publisher = {Springer Nature}, title = {{Antigravitropic PIN polarization maintains non-vertical growth in lateral roots}}, doi = {10.1038/s41477-023-01478-x}, volume = {9}, year = {2023}, } @article{14447, abstract = {Auxin belongs among major phytohormones and governs multiple aspects of plant growth and development. The establishment of auxin concentration gradients, determines, among other processes, plant organ positioning and growth responses to environmental stimuli. Herein we report the synthesis of new NBD- or DNS-labelled IAA derivatives and the elucidation of their biological activity, fluorescence properties and subcellular accumulation patterns in planta. These novel compounds did not show auxin-like activity, but instead antagonized physiological auxin effects. The DNS-labelled derivatives FL5 and FL6 showed strong anti-auxin activity in roots and hypocotyls, which also occurred at the level of gene transcription as confirmed by quantitative PCR analysis. The auxin antagonism of our derivatives was further demonstrated in vitro using an SPR-based binding assay. The NBD-labelled compound FL4 with the best fluorescence properties proved to be unsuitable to study auxin accumulation patterns in planta. On the other hand, the strongest anti-auxin activity possessing compounds FL5 and FL6 could be useful to study binding mechanisms to auxin receptors and for manipulations of auxin-regulated processes.}, author = {Bieleszová, Kristýna and Hladík, Pavel and Kubala, Martin and Napier, Richard and Brunoni, Federica and Gelová, Zuzana and Fiedler, Lukas and Kulich, Ivan and Strnad, Miroslav and Doležal, Karel and Novák, Ondřej and Friml, Jiří and Žukauskaitė, Asta}, issn = {1573-5087}, journal = {Plant Growth Regulation}, publisher = {Springer Nature}, title = {{New fluorescent auxin derivatives: anti-auxin activity and accumulation patterns in Arabidopsis thaliana}}, doi = {10.1007/s10725-023-01083-0}, year = {2023}, } @article{14709, abstract = {Amid the delays due to the global pandemic, in early October 2022, the auxin community gathered in the idyllic peninsula of Cavtat, Croatia. More than 170 scientists from across the world converged to discuss the latest advancements in fundamental and applied research in the field. The topics, from signalling and transport to plant architecture and response to the environment, show how auxin research must bridge from the molecular realm to macroscopic developmental responses. This is mirrored in this collection of reviews, contributed by participants of the Auxin 2022 meeting.}, author = {Del Bianco, Marta and Friml, Jiří and Strader, Lucia and Kepinski, Stefan}, issn = {1460-2431}, journal = {Journal of Experimental Botany}, number = {22}, pages = {6889--6892}, publisher = {Oxford University Press}, title = {{Auxin research: Creating tools for a greener future}}, doi = {10.1093/jxb/erad420}, volume = {74}, year = {2023}, } @article{14776, abstract = {Soluble chaperones residing in the endoplasmic reticulum (ER) play vitally important roles in folding and quality control of newly synthesized proteins that transiently pass through the ER en route to their final destinations. These soluble residents of the ER are themselves endowed with an ER retrieval signal that enables the cell to bring the escaped residents back from the Golgi. Here, by using purified proteins, we showed that Nicotiana tabacum phytaspase, a plant aspartate-specific protease, introduces two breaks at the C-terminus of the N. tabacum ER resident calreticulin-3. These cleavages resulted in removal of either a dipeptide or a hexapeptide from the C-terminus of calreticulin-3 encompassing part or all of the ER retrieval signal. Consistently, expression of the calreticulin-3 derivative mimicking the phytaspase cleavage product in Nicotiana benthamiana cells demonstrated loss of the ER accumulation of the protein. Notably, upon its escape from the ER, calreticulin-3 was further processed by an unknown protease(s) to generate the free N-terminal (N) domain of calreticulin-3, which was ultimately secreted into the apoplast. Our study thus identified a specific proteolytic enzyme capable of precise detachment of the ER retrieval signal from a plant ER resident protein, with implications for the further fate of the escaped resident.}, author = {Teplova, Anastasiia and Pigidanov, Artemii A. and Serebryakova, Marina V. and Golyshev, Sergei A. and Galiullina, Raisa A. and Chichkova, Nina V. and Vartapetian, Andrey B.}, issn = {1422-0067}, journal = {International Journal of Molecular Sciences}, keywords = {Inorganic Chemistry, Organic Chemistry, Physical and Theoretical Chemistry, Computer Science Applications, Spectroscopy, Molecular Biology, General Medicine, Catalysis}, number = {22}, publisher = {MDPI}, title = {{Phytaspase Is capable of detaching the endoplasmic reticulum retrieval signal from tobacco calreticulin-3}}, doi = {10.3390/ijms242216527}, volume = {24}, year = {2023}, } @article{13212, abstract = {Auxin is the major plant hormone regulating growth and development (Friml, 2022). Forward genetic approaches in the model plant Arabidopsis thaliana have identified major components of auxin signalling and established the canonical mechanism mediating transcriptional and thus developmental reprogramming. In this textbook view, TRANSPORT INHIBITOR RESPONSE 1 (TIR1)/AUXIN-SIGNALING F-BOX (AFBs) are auxin receptors, which act as F-box subunits determining the substrate specificity of the Skp1-Cullin1-F box protein (SCF) type E3 ubiquitin ligase complex. Auxin acts as a “molecular glue” increasing the affinity between TIR1/AFBs and the Aux/IAA repressors. Subsequently, Aux/IAAs are ubiquitinated and degraded, thus releasing auxin transcription factors from their repression making them free to mediate transcription of auxin response genes (Yu et al., 2022). Nonetheless, accumulating evidence suggests existence of rapid, non-transcriptional responses downstream of TIR1/AFBs such as auxin-induced cytosolic calcium (Ca2+) transients, plasma membrane depolarization and apoplast alkalinisation, all converging on the process of root growth inhibition and root gravitropism (Li et al., 2022). Particularly, these rapid responses are mostly contributed by predominantly cytosolic AFB1, while the long-term growth responses are mediated by mainly nuclear TIR1 and AFB2-AFB5 (Li et al., 2021; Prigge et al., 2020; Serre et al., 2021). How AFB1 conducts auxin-triggered rapid responses and how it is different from TIR1 and AFB2-AFB5 remains elusive. Here, we compare the roles of TIR1 and AFB1 in transcriptional and rapid responses by modulating their subcellular localization in Arabidopsis and by testing their ability to mediate transcriptional responses when part of the minimal auxin circuit reconstituted in yeast.}, author = {Chen, Huihuang and Li, Lanxin and Zou, Minxia and Qi, Linlin and Friml, Jiří}, issn = {1674-2052}, journal = {Molecular Plant}, number = {7}, pages = {1117--1119}, publisher = {Elsevier }, title = {{Distinct functions of TIR1 and AFB1 receptors in auxin signalling.}}, doi = {10.1016/j.molp.2023.06.007}, volume = {16}, year = {2023}, } @article{13266, abstract = {The 3′,5′-cyclic adenosine monophosphate (cAMP) is a versatile second messenger in many mammalian signaling pathways. However, its role in plants remains not well-recognized. Recent discovery of adenylate cyclase (AC) activity for transport inhibitor response 1/auxin-signaling F-box proteins (TIR1/AFB) auxin receptors and the demonstration of its importance for canonical auxin signaling put plant cAMP research back into spotlight. This insight briefly summarizes the well-established cAMP signaling pathways in mammalian cells and describes the turbulent and controversial history of plant cAMP research highlighting the major progress and the unresolved points. We also briefly review the current paradigm of auxin signaling to provide a background for the discussion on the AC activity of TIR1/AFB auxin receptors and its potential role in transcriptional auxin signaling as well as impact of these discoveries on plant cAMP research in general.}, author = {Qi, Linlin and Friml, Jiří}, issn = {1469-8137}, journal = {New Phytologist}, number = {2}, pages = {489--495}, publisher = {Wiley}, title = {{Tale of cAMP as a second messenger in auxin signaling and beyond}}, doi = {10.1111/nph.19123}, volume = {240}, year = {2023}, } @article{13209, abstract = {The phytohormone auxin plays central roles in many growth and developmental processes in plants. Development of chemical tools targeting the auxin pathway is useful for both plant biology and agriculture. Here we reveal that naproxen, a synthetic compound with anti-inflammatory activity in humans, acts as an auxin transport inhibitor targeting PIN-FORMED (PIN) transporters in plants. Physiological experiments indicate that exogenous naproxen treatment affects pleiotropic auxin-regulated developmental processes. Additional cellular and biochemical evidence indicates that naproxen suppresses auxin transport, specifically PIN-mediated auxin efflux. Moreover, biochemical and structural analyses confirm that naproxen binds directly to PIN1 protein via the same binding cavity as the indole-3-acetic acid substrate. Thus, by combining cellular, biochemical, and structural approaches, this study clearly establishes that naproxen is a PIN inhibitor and elucidates the underlying mechanisms. Further use of this compound may advance our understanding of the molecular mechanisms of PIN-mediated auxin transport and expand our toolkit in auxin biology and agriculture.}, author = {Xia, Jing and Kong, Mengjuan and Yang, Zhisen and Sun, Lianghanxiao and Peng, Yakun and Mao, Yanbo and Wei, Hong and Ying, Wei and Gao, Yongxiao and Friml, Jiří and Weng, Jianping and Liu, Xin and Sun, Linfeng and Tan, Shutang}, issn = {2590-3462}, journal = {Plant Communications}, number = {6}, publisher = {Elsevier }, title = {{Chemical inhibition of Arabidopsis PIN-FORMED auxin transporters by the anti-inflammatory drug naproxen}}, doi = {10.1016/j.xplc.2023.100632}, volume = {4}, year = {2023}, } @article{13201, abstract = {As a crucial nitrogen source, nitrate (NO3−) is a key nutrient for plants. Accordingly, root systems adapt to maximize NO3− availability, a developmental regulation also involving the phytohormone auxin. Nonetheless, the molecular mechanisms underlying this regulation remain poorly understood. Here, we identify low-nitrate-resistant mutant (lonr) in Arabidopsis (Arabidopsis thaliana), whose root growth fails to adapt to low-NO3− conditions. lonr2 is defective in the high-affinity NO3− transporter NRT2.1. lonr2 (nrt2.1) mutants exhibit defects in polar auxin transport, and their low-NO3−-induced root phenotype depends on the PIN7 auxin exporter activity. NRT2.1 directly associates with PIN7 and antagonizes PIN7-mediated auxin efflux depending on NO3− levels. These results reveal a mechanism by which NRT2.1 in response to NO3− limitation directly regulates auxin transport activity and, thus, root growth. This adaptive mechanism contributes to the root developmental plasticity to help plants cope with changes in NO3− availability.}, author = {Wang, Yalu and Yuan, Zhi and Wang, Jinyi and Xiao, Huixin and Wan, Lu and Li, Lanxin and Guo, Yan and Gong, Zhizhong and Friml, Jiří and Zhang, Jing}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {25}, publisher = {National Academy of Sciences}, title = {{The nitrate transporter NRT2.1 directly antagonizes PIN7-mediated auxin transport for root growth adaptation}}, doi = {10.1073/pnas.2221313120}, volume = {120}, year = {2023}, } @phdthesis{14510, author = {Gnyliukh, Nataliia}, isbn = {978-3-99078-037-4}, issn = {2663-337X}, keywords = {Clathrin-Mediated Endocytosis, vesicle scission, Dynamin-Related Protein 2, SH3P2, TPLATE complex, Total internal reflection fluorescence microscopy, Arabidopsis thaliana}, pages = {180}, publisher = {Institute of Science and Technology Austria}, title = {{Mechanism of clathrin-coated vesicle formation during endocytosis in plants}}, doi = {10.15479/at:ista:14510}, year = {2023}, } @article{10016, abstract = {Auxin has always been at the forefront of research in plant physiology and development. Since the earliest contemplations by Julius von Sachs and Charles Darwin, more than a century-long struggle has been waged to understand its function. This largely reflects the failures, successes, and inevitable progress in the entire field of plant signaling and development. Here I present 14 stations on our long and sometimes mystical journey to understand auxin. These highlights were selected to give a flavor of the field and to show the scope and limits of our current knowledge. A special focus is put on features that make auxin unique among phytohormones, such as its dynamic, directional transport network, which integrates external and internal signals, including self-organizing feedback. Accented are persistent mysteries and controversies. The unexpected discoveries related to rapid auxin responses and growth regulation recently disturbed our contentment regarding understanding of the auxin signaling mechanism. These new revelations, along with advances in technology, usher us into a new, exciting era in auxin research. }, author = {Friml, Jiří}, issn = {1943-0264}, journal = {Cold Spring Harbor Perspectives in Biology}, number = {5}, publisher = {Cold Spring Harbor Laboratory}, title = {{Fourteen stations of auxin}}, doi = {10.1101/cshperspect.a039859 }, volume = {14}, year = {2022}, } @article{10583, abstract = {The synthetic strigolactone (SL) analog, rac-GR24, has been instrumental in studying the role of SLs as well as karrikins because it activates the receptors DWARF14 (D14) and KARRIKIN INSENSITIVE 2 (KAI2) of their signaling pathways, respectively. Treatment with rac-GR24 modifies the root architecture at different levels, such as decreasing the lateral root density (LRD), while promoting root hair elongation or flavonol accumulation. Previously, we have shown that the flavonol biosynthesis is transcriptionally activated in the root by rac-GR24 treatment, but, thus far, the molecular players involved in that response have remained unknown. To get an in-depth insight into the changes that occur after the compound is perceived by the roots, we compared the root transcriptomes of the wild type and the more axillary growth2 (max2) mutant, affected in both SL and karrikin signaling pathways, with and without rac-GR24 treatment. Quantitative reverse transcription (qRT)-PCR, reporter line analysis and mutant phenotyping indicated that the flavonol response and the root hair elongation are controlled by the ELONGATED HYPOCOTYL 5 (HY5) and MYB12 transcription factors, but HY5, in contrast to MYB12, affects the LRD as well. Furthermore, we identified the transcription factors TARGET OF MONOPTEROS 5 (TMO5) and TMO5 LIKE1 as negative and the Mediator complex as positive regulators of the rac-GR24 effect on LRD. Altogether, hereby, we get closer toward understanding the molecular mechanisms that underlay the rac-GR24 responses in the root.}, author = {Struk, Sylwia and Braem, Lukas and Matthys, Cedrick and Walton, Alan and Vangheluwe, Nick and Van Praet, Stan and Jiang, Lingxiang and Baster, Pawel and De Cuyper, Carolien and Boyer, Francois-Didier and Stes, Elisabeth and Beeckman, Tom and Friml, Jiří and Gevaert, Kris and Goormachtig, Sofie}, issn = {1471-9053}, journal = {Plant & Cell Physiology}, keywords = {flavonols, MAX2, rac-Gr24, RNA-seq, root development, transcriptional regulation}, number = {1}, pages = {104--119}, publisher = {Oxford University Press}, title = {{Transcriptional analysis in the Arabidopsis roots reveals new regulators that link rac-GR24 treatment with changes in flavonol accumulation, root hair elongation and lateral root density}}, doi = {10.1093/pcp/pcab149}, volume = {63}, year = {2022}, } @article{10717, abstract = {Much of what we know about the role of auxin in plant development derives from exogenous manipulations of auxin distribution and signaling, using inhibitors, auxins and auxin analogs. In this context, synthetic auxin analogs, such as 1-Naphtalene Acetic Acid (1-NAA), are often favored over the endogenous auxin indole-3-acetic acid (IAA), in part due to their higher stability. While such auxin analogs have proven to be instrumental to reveal the various faces of auxin, they display in some cases distinct bioactivities compared to IAA. Here, we focused on the effect of auxin analogs on the accumulation of PIN proteins in Brefeldin A-sensitive endosomal aggregations (BFA bodies), and the correlation with the ability to elicit Ca 2+ responses. For a set of commonly used auxin analogs, we evaluated if auxin-analog induced Ca 2+ signaling inhibits PIN accumulation. Not all auxin analogs elicited a Ca 2+ response, and their differential ability to elicit Ca 2+ responses correlated partially with their ability to inhibit BFA-body formation. However, in tir1/afb and cngc14, 1-NAA-induced Ca 2+ signaling was strongly impaired, yet 1-NAA still could inhibit PIN accumulation in BFA bodies. This demonstrates that TIR1/AFB-CNGC14-dependent Ca 2+ signaling does not inhibit BFA body formation in Arabidopsis roots.}, author = {Wang, R and Himschoot, E and Grenzi, M and Chen, J and Safi, A and Krebs, M and Schumacher, K and Nowack, MK and Moeder, W and Yoshioka, K and Van Damme, D and De Smet, I and Geelen, D and Beeckman, T and Friml, Jiří and Costa, A and Vanneste, S}, issn = {1460-2431}, journal = {Journal of Experimental Botany}, number = {8}, publisher = {Oxford Academic}, title = {{Auxin analog-induced Ca2+ signaling is independent of inhibition of endosomal aggregation in Arabidopsis roots}}, doi = {10.1093/jxb/erac019}, volume = {73}, year = {2022}, } @article{10719, abstract = {Auxin, one of the first identified and most widely studied phytohormones, has been and will remain a hot topic in plant biology. After more than a century of passionate exploration, the mysteries of its synthesis, transport, signaling, and metabolism have largely been unlocked. Due to the rapid development of new technologies, new methods, and new genetic materials, the study of auxin has entered the fast lane over the past 30 years. Here, we highlight advances in understanding auxin signaling, including auxin perception, rapid auxin responses, TRANSPORT INHIBITOR RESPONSE 1 and AUXIN SIGNALING F-boxes (TIR1/AFBs)-mediated transcriptional and non-transcriptional branches, and the epigenetic regulation of auxin signaling. We also focus on feedback inhibition mechanisms that prevent the over-amplification of auxin signals. In addition, we cover the TRANSMEMBRANE KINASEs (TMKs)-mediated non-canonical signaling, which converges with TIR1/AFBs-mediated transcriptional regulation to coordinate plant growth and development. The identification of additional auxin signaling components and their regulation will continue to open new avenues of research in this field, leading to an increasingly deeper, more comprehensive understanding of how auxin signals are interpreted at the cellular level to regulate plant growth and development.}, author = {Yu, Z and Zhang, F and Friml, Jiří and Ding, Z}, issn = {1744-7909}, journal = {Journal of Integrative Plant Biology}, number = {2}, pages = {371--392}, publisher = {Wiley}, title = {{Auxin signaling: Research advances over the past 30 years}}, doi = {10.1111/jipb.13225}, volume = {64}, year = {2022}, } @article{10768, abstract = {Among the most fascinated properties of the plant hormone auxin is its ability to promote formation of its own directional transport routes. These gradually narrowing auxin channels form from the auxin source toward the sink and involve coordinated, collective polarization of individual cells. Once established, the channels provide positional information, along which new vascular strands form, for example, during organogenesis, regeneration, or leave venation. The main prerequisite of this still mysterious auxin canalization mechanism is a feedback between auxin signaling and its directional transport. This is manifested by auxin-induced re-arrangements of polar, subcellular localization of PIN-FORMED (PIN) auxin exporters. Immanent open questions relate to how position of auxin source and sink as well as tissue context are sensed and translated into tissue polarization and how cells communicate to polarize coordinately. Recently, identification of the first molecular players opens new avenues into molecular studies of this intriguing example of self-organizing plant development.}, author = {Hajny, Jakub and Tan, Shutang and Friml, Jiří}, issn = {1369-5266}, journal = {Current Opinion in Plant Biology}, number = {2}, publisher = {Elsevier}, title = {{Auxin canalization: From speculative models toward molecular players}}, doi = {10.1016/j.pbi.2022.102174}, volume = {65}, year = {2022}, } @article{10841, abstract = {In eukaryotes, clathrin-coated vesicles (CCVs) facilitate the internalization of material from the cell surface as well as the movement of cargo in post-Golgi trafficking pathways. This diversity of functions is partially provided by multiple monomeric and multimeric clathrin adaptor complexes that provide compartment and cargo selectivity. The adaptor-protein assembly polypeptide-1 (AP-1) complex operates as part of the secretory pathway at the trans-Golgi network (TGN), while the AP-2 complex and the TPLATE complex jointly operate at the plasma membrane to execute clathrin-mediated endocytosis. Key to our further understanding of clathrin-mediated trafficking in plants will be the comprehensive identification and characterization of the network of evolutionarily conserved and plant-specific core and accessory machinery involved in the formation and targeting of CCVs. To facilitate these studies, we have analyzed the proteome of enriched TGN/early endosome-derived and endocytic CCVs isolated from dividing and expanding suspension-cultured Arabidopsis (Arabidopsis thaliana) cells. Tandem mass spectrometry analysis results were validated by differential chemical labeling experiments to identify proteins co-enriching with CCVs. Proteins enriched in CCVs included previously characterized CCV components and cargos such as the vacuolar sorting receptors in addition to conserved and plant-specific components whose function in clathrin-mediated trafficking has not been previously defined. Notably, in addition to AP-1 and AP-2, all subunits of the AP-4 complex, but not AP-3 or AP-5, were found to be in high abundance in the CCV proteome. The association of AP-4 with suspension-cultured Arabidopsis CCVs is further supported via additional biochemical data.}, author = {Dahhan, DA and Reynolds, GD and Cárdenas, JJ and Eeckhout, D and Johnson, Alexander J and Yperman, K and Kaufmann, Walter and Vang, N and Yan, X and Hwang, I and Heese, A and De Jaeger, G and Friml, Jiří and Van Damme, D and Pan, J and Bednarek, SY}, issn = {1532-298x}, journal = {Plant Cell}, number = {6}, pages = {2150--2173}, publisher = {Oxford Academic}, title = {{Proteomic characterization of isolated Arabidopsis clathrin-coated vesicles reveals evolutionarily conserved and plant-specific components}}, doi = {10.1093/plcell/koac071}, volume = {34}, year = {2022}, } @article{10888, abstract = {Despite the growing interest in using chemical genetics in plant research, small molecule target identification remains a major challenge. The cellular thermal shift assay coupled with high-resolution mass spectrometry (CETSA MS) that monitors changes in the thermal stability of proteins caused by their interactions with small molecules, other proteins, or posttranslational modifications, allows the discovery of drug targets or the study of protein–metabolite and protein–protein interactions mainly in mammalian cells. To showcase the applicability of this method in plants, we applied CETSA MS to intact Arabidopsis thaliana cells and identified the thermal proteome of the plant-specific glycogen synthase kinase 3 (GSK3) inhibitor, bikinin. A comparison between the thermal and the phosphoproteomes of bikinin revealed the auxin efflux carrier PIN-FORMED1 (PIN1) as a substrate of the Arabidopsis GSK3s that negatively regulate the brassinosteroid signaling. We established that PIN1 phosphorylation by the GSK3s is essential for maintaining its intracellular polarity that is required for auxin-mediated regulation of vascular patterning in the leaf, thus revealing cross-talk between brassinosteroid and auxin signaling.}, author = {Lu, Qing and Zhang, Yonghong and Hellner, Joakim and Giannini, Caterina and Xu, Xiangyu and Pauwels, Jarne and Ma, Qian and Dejonghe, Wim and Han, Huibin and Van De Cotte, Brigitte and Impens, Francis and Gevaert, Kris and De Smet, Ive and Friml, Jiří and Molina, Daniel Martinez and Russinova, Eugenia}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {11}, publisher = {Proceedings of the National Academy of Sciences}, title = {{Proteome-wide cellular thermal shift assay reveals unexpected cross-talk between brassinosteroid and auxin signaling}}, doi = {10.1073/pnas.2118220119}, volume = {119}, year = {2022}, } @article{11589, abstract = {Calcium-dependent protein kinases (CPK) are key components of a wide array of signaling pathways, translating stress and nutrient signaling into the modulation of cellular processes such as ion transport and transcription. However, not much is known about CPKs in endomembrane trafficking. Here, we screened for CPKs that impact on root growth and gravitropism, by overexpressing constitutively active forms of CPKs under the control of an inducible promoter in Arabidopsis thaliana. We found that inducible overexpression of an constitutive active CPK30 (CA-CPK30) resulted in a loss of root gravitropism and ectopic auxin accumulation in the root tip. Immunolocalization revealed that CA-CPK30 roots have reduced PIN protein levels, PIN1 polarity defects and impaired Brefeldin A (BFA)-sensitive trafficking. Moreover, FM4-64 uptake was reduced, indicative of a defect in endocytosis. The effects on BFA-sensitive trafficking were not specific to PINs, as BFA could not induce aggregation of ARF1- and CHC-labeled endosomes in CA-CPK30. Interestingly, the interference with BFA-body formation, could be reverted by increasing the extracellular pH, indicating a pH-dependence of this CA-CPK30 effect. Altogether, our data reveal an important role for CPK30 in root growth regulation and endomembrane trafficking in Arabidopsis thaliana.}, author = {Wang, Ren and Himschoot, Ellie and Chen, Jian and Boudsocq, Marie and Geelen, Danny and Friml, Jiří and Beeckman, Tom and Vanneste, Steffen}, issn = {1664-462X}, journal = {Frontiers in Plant Science}, publisher = {Frontiers}, title = {{Constitutive active CPK30 interferes with root growth and endomembrane trafficking in Arabidopsis thaliana}}, doi = {10.3389/fpls.2022.862398}, volume = {13}, year = {2022}, }