@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}, } @inbook{1806, abstract = {The generation of asymmetry, at both cellular and tissue level, is one of the most essential capabilities of all eukaryotic organisms. It mediates basically all multicellular development ranging from embryogenesis and de novo organ formation till responses to various environmental stimuli. In plants, the awe-inspiring number of such processes is regulated by phytohormone auxin and its directional, cell-to-cell transport. The mediators of this transport, PIN auxin transporters, are asymmetrically localized at the plasma membrane, and this polar localization determines the directionality of intercellular auxin flow. Thus, auxin transport contributes crucially to the generation of local auxin gradients or maxima, which instruct given cell to change its developmental program. Here, we introduce and discuss the molecular components and cellular mechanisms regulating the generation and maintenance of cellular PIN polarity, as the general hallmarks of cell polarity in plants.}, author = {Baster, Pawel and Friml, Jiří}, booktitle = {Auxin and Its Role in Plant Development}, editor = {Zažímalová, Eva and Petrášek, Jan and Benková, Eva}, pages = {143 -- 170}, publisher = {Springer}, title = {{Auxin on the road navigated by cellular PIN polarity}}, doi = {10.1007/978-3-7091-1526-8_8}, year = {2014}, } @article{2443, abstract = {The mode of action of auxin is based on its non-uniform distribution within tissues and organs. Despite the wide use of several auxin analogues in research and agriculture, little is known about the specificity of different auxin-related transport and signalling processes towards these compounds. Using seedlings of Arabidopsis thaliana and suspension-cultured cells of Nicotiana tabacum (BY-2), the physiological activity of several auxin analogues was investigated, together with their capacity to induce auxin-dependent gene expression, to inhibit endocytosis and to be transported across the plasma membrane. This study shows that the specificity criteria for different auxin-related processes vary widely. Notably, the special behaviour of some synthetic auxin analogues suggests that they might be useful tools in investigations of the molecular mechanism of auxin action. Thus, due to their differential stimulatory effects on DR5 expression, indole-3-propionic (IPA) and 2,4,5-trichlorophenoxy acetic (2,4,5-T) acids can serve in studies of TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALLING F-BOX (TIR1/AFB)-mediated auxin signalling, and 5-fluoroindole-3-acetic acid (5-F-IAA) can help to discriminate between transcriptional and non-transcriptional pathways of auxin signalling. The results demonstrate that the major determinants for the auxin-like physiological potential of a particular compound are very complex and involve its chemical and metabolic stability, its ability to distribute in tissues in a polar manner and its activity towards auxin signalling machinery.}, author = {Simon, Sibu and Kubeš, Martin and Baster, Pawel and Robert, Stéphanie and Dobrev, Petre and Friml, Jirí and Petrášek, Jan and Zažímalová, Eva}, journal = {New Phytologist}, number = {4}, pages = {1034 -- 1048}, publisher = {Wiley}, title = {{Defining the selectivity of processes along the auxin response chain: A study using auxin analogues}}, doi = {10.1111/nph.12437}, volume = {200}, year = {2013}, } @article{2448, abstract = {Cell-to-cell directional flow of the phytohormone auxin is primarily established by polar localization of the PIN auxin transporters, a process tightly regulated at multiple levels by auxin itself. We recently reported that, in the context of strong auxin flows, activity of the vacuolar ZIFL1.1 transporter is required for fine-tuning of polar auxin transport rates in the Arabidopsis root. In particular, ZIFL1.1 function protects plasma-membrane stability of the PIN2 carrier in epidermal root tip cells under conditions normally triggering PIN2 degradation. Here, we show that ZIFL1.1 activity at the root tip also promotes PIN1 plasma-membrane abundance in central cylinder cells, thus supporting the notion that ZIFL1.1 acts as a general positive modulator of polar auxin transport in roots.}, author = {Remy, Estelle and Baster, Pawel and Friml, Jirí and Duque, Paula}, journal = {Plant Signaling & Behavior}, number = {10}, publisher = {Taylor & Francis}, title = {{ZIFL1.1 transporter modulates polar auxin transport by stabilizing membrane abundance of multiple PINs in Arabidopsis root tip}}, doi = {10.4161/psb.25688}, volume = {8}, year = {2013}, } @article{2821, abstract = {Many key aspects of plant development are regulated by the polarized transport of the phytohormone auxin. Cellular auxin efflux, the rate-limiting step in this process, has been shown to rely on the coordinated action of PIN-formed (PIN) and B-type ATP binding cassette (ABCB) carriers. Here, we report that polar auxin transport in the Arabidopsis thaliana root also requires the action of a Major Facilitator Superfamily (MFS) transporter, Zinc-Induced Facilitator-Like 1 (ZIFL1). Sequencing, promoter-reporter, and fluorescent protein fusion experiments indicate that the full-length ZIFL1.1 protein and a truncated splice isoform, ZIFL1.3, localize to the tonoplast of root cells and the plasma membrane of leaf stomatal guard cells, respectively. Using reverse genetics, we show that the ZIFL1.1 transporter regulates various root auxin-related processes, while the ZIFL1.3 isoform mediates drought tolerance by regulating stomatal closure. Auxin transport and immunolocalization assays demonstrate that ZIFL1.1 indirectly modulates cellular auxin efflux during shootward auxin transport at the root tip, likely by regulating plasma membrane PIN2 abundance. Finally, heterologous expression in yeast revealed that ZIFL1.1 and ZIFL1.3 share H+-coupled K+ transport activity. Thus, by determining the subcellular and tissue distribution of two isoforms, alternative splicing dictates a dual function for the ZIFL1 transporter. We propose that this MFS carrier regulates stomatal movements and polar auxin transport by modulating potassium and proton fluxes in Arabidopsis cells.}, author = {Remy, Estelle and Cabrito, Tânia and Baster, Pawel and Batista, Rita and Teixeira, Miguel and Friml, Jirí and Sá Correia, Isabel and Duque, Paula}, journal = {Plant Cell}, number = {3}, pages = {901 -- 926}, publisher = {American Society of Plant Biologists}, title = {{A major facilitator superfamily transporter plays a dual role in polar auxin transport and drought stress tolerance in Arabidopsis}}, doi = {10.1105/tpc.113.110353}, volume = {25}, year = {2013}, } @article{2919, abstract = {The distribution of the phytohormone auxin regulates many aspects of plant development including growth response to gravity. Gravitropic root curvature involves coordinated and asymmetric cell elongation between the lower and upper side of the root, mediated by differential cellular auxin levels. The asymmetry in the auxin distribution is established and maintained by a spatio-temporal regulation of the PIN-FORMED (PIN) auxin transporter activity. We provide novel insights into the complex regulation of PIN abundance and activity during root gravitropism. We show that PIN2 turnover is differentially regulated on the upper and lower side of gravistimulated roots by distinct but partially overlapping auxin feedback mechanisms. In addition to regulating transcription and clathrin-mediated internalization, auxin also controls PIN abundance at the plasma membrane by promoting their vacuolar targeting and degradation. This effect of elevated auxin levels requires the activity of SKP-Cullin-F-box TIR1/AFB (SCF TIR1/AFB)-dependent pathway. Importantly, also suboptimal auxin levels mediate PIN degradation utilizing the same signalling pathway. These feedback mechanisms are functionally important during gravitropic response and ensure fine-tuning of auxin fluxes for maintaining as well as terminating asymmetric growth.}, author = {Baster, Pawel and Robert, Stéphanie and Kleine Vehn, Jürgen and Vanneste, Steffen and Kania, Urszula and Grunewald, Wim and De Rybel, Bert and Beeckman, Tom and Friml, Jirí}, journal = {EMBO Journal}, number = {2}, pages = {260 -- 274}, publisher = {Wiley-Blackwell}, title = {{SCF^TIR1 AFB-auxin signalling regulates PIN vacuolar trafficking and auxin fluxes during root gravitropism}}, doi = {10.1038/emboj.2012.310}, volume = {32}, year = {2013}, } @article{3105, abstract = {Growth and development are coordinated by an array of intercellular communications. Known plant signaling molecules include phytohormones and hormone peptides. Although both classes can be implicated in the same developmental processes, little is known about the interplay between phytohormone action and peptide signaling within the cellular microenvironment. We show that genes coding for small secretory peptides, designated GOLVEN (GLV), modulate the distribution of the phytohormone auxin. The deregulation of the GLV function impairs the formation of auxin gradients and alters the reorientation of shoots and roots after a gravity stimulus. Specifically, the GLV signal modulates the trafficking dynamics of the auxin efflux carrier PIN-FORMED2 involved in root tropic responses and meristem organization. Our work links the local action of secretory peptides with phytohormone transport. Root growth factor (RGF) or GOLVEN (GLV) secreted peptides have previously been implicated in meristem regulation. Whitford et al. now show that RGF/GLV peptides induce rapid relocalization of the auxin efflux regulator PIN2, regulate auxin gradients, and modulate auxin-dependent root responses to specific stimuli.}, author = {Whitford, Ryan and Fernandez, Ana and Tejos, Ricardo and Pérez, Amparo Cuéllar and Kleine-Vehn, Jürgen and Vanneste, Steffen and Drozdzecki, Andrzej and Leitner, Johannes and Abas, Lindy and Aerts, Maarten and Hoogewijs, Kurt and Pawel Baster and De Groodt, Ruth and Lin, Yao-Cheng and Storme, Véronique and Van de Peer, Yves and Beeckman, Tom and Madder, Annemieke and Devreese, Bart and Luschnig, Christian and Jirí Friml and Hilson, Pierre}, journal = {Developmental Cell}, number = {3}, pages = {678 -- 685}, publisher = {Cell Press}, title = {{GOLVEN secretory peptides regulate auxin carrier turnover during plant gravitropic responses}}, doi = {10.1016/j.devcel.2012.02.002}, volume = {22}, year = {2012}, } @article{3075, abstract = { Spatial distribution of the plant hormone auxin regulates multiple aspects of plant development. These self-regulating auxin gradients are established by the action of PIN auxin transporters, whose activity is regulated by their constitutive cycling between the plasma membrane and endosomes. Here, we show that auxin signaling by the auxin receptor AUXIN-BINDING PROTEIN 1 (ABP1) inhibits the clathrin-mediated internalization of PIN proteins. ABP1 acts as a positive factor in clathrin recruitment to the plasma membrane, thereby promoting endocytosis. Auxin binding to ABP1 interferes with this action and leads to the inhibition of clathrin-mediated endocytosis. Our study demonstrates that ABP1 mediates a nontranscriptional auxin signaling that regulates the evolutionarily conserved process of clathrin-mediated endocytosis and suggests that this signaling may be essential for the developmentally important feedback of auxin on its own transport.}, author = {Robert, Stéphanie and Kleine-Vehn, Jürgen and Barbez, Elke and Sauer, Michael and Paciorek, Tomasz and Pawel Baster and Vanneste, Steffen and Zhang, Jing and Sibu Simon and Čovanová, Milada and Hayashi, Kenichiro and Dhonukshe, Pankaj and Yang, Zhenbiao and Bednarek, Sebastian Y and Jones, Alan M and Luschnig, Christian and Aniento, Fernando and Zažímalová, Eva and Jirí Friml}, journal = {Cell}, number = {1}, pages = {111 -- 121}, publisher = {Cell Press}, title = {{ABP1 mediates auxin inhibition of clathrin-dependent endocytosis in Arabidopsis}}, doi = {10.1016/j.cell.2010.09.027}, volume = {143}, year = {2010}, }