@article{10389, abstract = {We perform numerical simulations to study self-assembly of nanoparticles mediated by an elastic planar surface. We show how the nontrivial elastic response to deformations of these surfaces leads to anisotropic interactions between the particles resulting in aggregates having different geometrical features. The morphology of the patterns can be controlled by the mechanical properties of the surface and the strength of the particle adhesion. We use simple scaling arguments to understand the formation of the different structures, and we show how the adhering particles can cause the underlying elastic substrate to wrinkle if two of its opposite edges are clamped. Finally, we discuss the implications of our results and suggest how elastic surfaces could be used in nanofabrication.}, author = {Šarić, Anđela and Cacciuto, Angelo}, issn = {1744-6848}, journal = {Soft Matter}, keywords = {condensed matter physics, general chemistry}, number = {18}, publisher = {Royal Society of Chemistry}, title = {{Soft elastic surfaces as a platform for particle self-assembly}}, doi = {10.1039/c1sm05773a}, volume = {7}, year = {2011}, } @article{1048, abstract = {We produce an ultracold and dense sample of rovibronic ground state Cs 2 molecules close to the regime of quantum degeneracy, in a single hyperfine level, in the presence of an optical lattice. The molecules are individually trapped, in the motional ground state of an optical lattice well, with a lifetime of 8 s. For preparation, we start with a zero-temperature atomic Mott-insulator state with optimized double-site occupancy and efficiently associate weakly-bound dimer molecules on a Feshbach resonance. Despite extremely weak Franck-Condon wavefunction overlap, the molecules are subsequently transferred with >50% efficiency to the rovibronic ground state by a stimulated four-photon process. Our results present a crucial step towards the generation of Bose-Einstein condensates of ground-state molecules and, when suitably generalized to polar heteronuclear molecules such as RbCs, the realization of dipolar many-body quantum-gas phases in periodic potentials.}, author = {Nägerl, Hanns and Mark, Manfred and Haller, Elmar and Gustavsson, Mattias and Hart, Russell and Danzl, Johann G}, journal = {Journal of Physics: Conference Series}, number = {1}, publisher = {IOP Publishing Ltd.}, title = {{Ultracold and dense samples of ground-state molecules in lattice potentials}}, doi = {10.1088/1742-6596/264/1/012015}, volume = {264}, year = {2011}, } @article{1050, abstract = {We present experimentally derived potential curves 1?and spin-orbit interaction functions for the strongly perturbed AΣu+ 3?and bΠu states of the cesium dimer. The results are based on data from several sources. Laser-induced fluorescence Fourier transform spectroscopy (LIF FTS) was used some time ago in the Laboratoire Aimé Cotton primarily to study the XΣg+ state. More recent work at Tsinghua University provides information from moderate 3?resolution spectroscopy on the lowest levels of the bΠ0u± state as well as additional high-resolution data. From Innsbruck University, we have precision data obtained with cold Cs2 molecules. Recent data from Temple University was obtained using the optical-optical double resonance polarization spectroscopy technique, and finally, a group at the University of Latvia has added additional LIF FTS data. In the Hamiltonian matrix, we have used analytic potentials (the expanded Morse oscillator form) with both finite-difference (FD) coupled-channel and discrete variable representation (DVR) calculations of the term values. Fitted diagonal and off-diagonal spin-orbit functions are obtained and compared with ab initio results from Temple and Moscow State universities.}, author = {Bai, Jianmei and Ahmed, Ergin and Beser, Bediha and Guan, Yafei and Kotochigova, Svetlana and Lyyra, Marjatta and Ashman, Seth and Wolfe, Christopher and Huennekens, John and Xie, Feng and Li, Dan and Li, Li and Tamanis, Maris and Ferber, Ruvin and Drozdova, Anastasia and Pazyuk, Elena and Stolyarov, Andrey and Danzl, Johann G and Nägerl, Hanns and Bouloufa, Nadia and Dulieu, Olivier and Amiot, Claude and Salami, Houssam and Bergeman, Thomas}, journal = { Physical Review A - Atomic, Molecular, and Optical Physics}, number = {3}, publisher = {American Physical Society}, title = {{Global analysis of data on the spin-orbit-coupled A 1Σu+ and b 3Πu inf states of Cs2}}, doi = {10.1103/PhysRevA.83.032514}, volume = {83}, year = {2011}, } @article{1051, abstract = {We demonstrate the temporal Talbot effect for trapped matter waves using ultracold atoms in an optical lattice. We investigate the phase evolution of an array of essentially non-interacting matter waves and observe matter-wave collapse and revival in the form of a Talbot interference pattern. By using long expansion times, we image momentum space with sub-recoil resolution, allowing us to observe fractional Talbot fringes up to tenth order.}, author = {Mark, Manfred and Haller, Elmar and Danzl, Johann G and Lauber, Katharina and Gustavsson, Mattias and Nägerl, Hanns}, journal = {New Journal of Physics}, publisher = {IOP Publishing Ltd.}, title = {{Demonstration of the temporal matter-wave Talbot effect for trapped matter waves}}, doi = {10.1088/1367-2630/13/8/085008}, volume = {13}, year = {2011}, } @article{1052, abstract = {The present paper aims at finding optimal parameters for trapping of Cs 2 molecules in optical lattices, with the perspective of creating a quantum degenerate gas of ground-state molecules. We have calculated dynamic polarizabilities of Cs 2 molecules subject to an oscillating electric field, using accurate potential curves and electronic transition dipole moments. We show that for some particular wavelengths of the optical lattice, called "magic wavelengths", the polarizability of the ground-state molecules is equal to the one of a Feshbach molecule. As the creation of the sample of ground-state molecules relies on an adiabatic population transfer from weakly-bound molecules created on a Feshbach resonance, such a coincidence ensures that both the initial and final states are favorably trapped by the lattice light, allowing optimized transfer in agreement with the experimental observation.}, author = {Vexiau, Romain and Bouloufa, Nadia and Aymar, Mireille and Danzl, Johann G and Mark, Manfred and Nägerl, Hanns and Dulieu, Olivier}, journal = {European Physical Journal D}, number = {1-2}, pages = {243 -- 250}, publisher = {Springer}, title = {{Optimal trapping wavelengths of Cs 2 molecules in an optical lattice}}, doi = {10.1140/epjd/e2011-20085-4}, volume = {65}, year = {2011}, } @article{1053, abstract = {We perform precision measurements on a Mott-insulator quantum state of ultracold atoms with tunable interactions. We probe the dependence of the superfluid-to-Mott-insulator transition on the interaction strength and explore the limits of the standard Bose-Hubbard model description. By tuning the on-site interaction energies to values comparable to the interband separation, we are able to quantitatively measure number-dependent shifts in the excitation spectrum caused by effective multibody interactions.}, author = {Mark, Manfred and Haller, Elmar and Lauber, Katharina and Danzl, Johann G and Daley, Andrew and Nägerl, Hanns}, journal = {Physical Review Letters}, number = {17}, publisher = {American Physical Society}, title = {{Precision measurements on a tunable Mott insulator of ultracold atoms}}, doi = {10.1103/PhysRevLett.107.175301}, volume = {107}, year = {2011}, } @article{1054, abstract = {We investigate local three-body correlations for bosonic particles in three dimensions and one dimension as a function of the interaction strength. The three-body correlation function g(3) is determined by measuring the three-body recombination rate in an ultracold gas of Cs atoms. In three dimensions, we measure the dependence of g(3) on the gas parameter in a BEC, finding good agreement with the theoretical prediction accounting for beyond-mean-field effects. In one dimension, we observe a reduction of g( 3) by several orders of magnitude upon increasing interactions from the weakly interacting BEC to the strongly interacting Tonks-Girardeau regime, in good agreement with predictions from the Lieb-Liniger model for all strengths of interaction.}, author = {Haller, Elmar and Rabie, Mahmoud and Mark, Manfred and Danzl, Johann G and Hart, Russell and Lauber, Katharina and Pupillo, Guido and Nägerl, Hanns}, journal = {Physical Review Letters}, number = {23}, publisher = {American Physical Society}, title = {{Three-body correlation functions and recombination rates for bosons in three dimensions and one dimension}}, doi = {10.1103/PhysRevLett.107.230404}, volume = {107}, year = {2011}, } @article{3086, abstract = {PIN-FORMED (PIN)-dependent auxin transport is essential for plant development and its modulation in response to the environment or endogenous signals. A NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3)-like protein, MACCHI-BOU 4 (MAB4), has been shown to control PIN1 localization during organ formation, but its contribution is limited. The Arabidopsis genome contains four genes, MAB4/ENP/NPY1-LIKE1 (MEL1), MEL2, MEL3 and MEL4, highly homologous to MAB4. Genetic analysis disclosed functional redundancy between MAB4 and MEL genes in regulation of not only organ formation but also of root gravitropism, revealing that NPH3 family proteins have a wider range of functions than previously suspected. Multiple mutants showed severe reduction in PIN abundance and PIN polar localization, leading to defective expression of an auxin responsive marker DR5rev::GFP. Pharmacological analyses and fluorescence recovery after photo-bleaching experiments showed that mel mutations increase PIN2 internalization from the plasma membrane, but affect neither intracellular PIN2 trafficking nor PIN2 lateral diffusion at the plasma membrane. Notably, all MAB4 subfamily proteins show polar localization at the cell periphery in plants. The MAB4 polarity was almost identical to PIN polarity. Our results suggest that the MAB4 subfamily proteins specifically retain PIN proteins in a polarized manner at the plasma membrane, thus controlling directional auxin transport and plant development.}, author = {Furutani, Masahiko and Sakamoto, Norihito and Yoshida, Shuhei and Kajiwara, Takahito and Robert, Hélène S and Jirí Friml and Tasaka, Masao}, journal = {Development}, number = {10}, pages = {2069 -- 2078}, publisher = {Company of Biologists}, title = {{Polar localized NPH3-like proteins regulate polarity and endocytosis of PIN-FORMED auxin efflux carriers}}, doi = {10.1242/dev.057745}, volume = {138}, year = {2011}, } @article{3087, abstract = {Endocytosis is a crucial mechanism by which eukaryotic cells internalize extracellular and plasma membrane material, and it is required for a multitude of cellular and developmental processes in unicellular and multicellular organisms. In animals and yeast, the best characterized pathway for endocytosis depends on the function of the vesicle coat protein clathrin. Clathrinmediated endocytosis has recently been demonstrated also in plant cells, but its physiological and developmental roles remain unclear. Here, we assessed the roles of the clathrin-mediated mechanism of endocytosis in plants by genetic means. We interfered with clathrin heavy chain (CHC) function through mutants and dominant-negative approaches in Arabidopsis thaliana and established tools to manipulate clathrin function in a cell type-specific manner. The chc2 single mutants and dominant-negative CHC1 (HUB) transgenic lines were defective in bulk endocytosis as well as in internalization of prominent plasma membrane proteins. Interference with clathrin-mediated endocytosis led to defects in constitutive endocytic recycling of PIN auxin transporters and their polar distribution in embryos and roots. Consistent with this, these lines had altered auxin distribution patterns and associated auxin transport-related phenotypes, such as aberrant embryo patterning, imperfect cotyledon specification, agravitropic growth, and impaired lateral root organogenesis. Together, these data demonstrate a fundamental role for clathrin function in cell polarity, growth, patterning, and organogenesis in plants.}, author = {Kitakura, Saeko and Vanneste, Steffen and Robert, Stéphanie and Löfke, Christian and Teichmann, Thomas and Tanaka, Hirokazu and Jirí Friml}, journal = {Plant Cell}, number = {5}, pages = {1920 -- 1931}, publisher = {American Society of Plant Biologists}, title = {{Clathrin mediates endocytosis and polar distribution of PIN auxin transporters in Arabidopsis}}, doi = {10.1105/tpc.111.083030}, volume = {23}, year = {2011}, } @article{3088, abstract = {Background: Whereas the majority of animals develop toward a predetermined body plan, plants show iterative growth and continually produce new organs and structures from actively dividing meristems. This raises an intriguing question: How are these newly developed organs patterned? In Arabidopsis embryos, radial symmetry is broken by the bisymmetric specification of the cotyledons in the apical domain. Subsequently, this bisymmetry is propagated to the root promeristem. Results: Here we present a mutually inhibitory feedback loop between auxin and cytokinin that sets distinct boundaries of hormonal output. Cytokinins promote the bisymmetric distribution of the PIN-FORMED (PIN) auxin efflux proteins, which channel auxin toward a central domain. High auxin promotes transcription of the cytokinin signaling inhibitor AHP6, which closes the interaction loop. This bisymmetric auxin response domain specifies the differentiation of protoxylem in a bisymmetric pattern. In embryonic roots, cytokinin is required to translate a bisymmetric auxin response in the cotyledons to a bisymmetric vascular pattern in the root promeristem. Conclusions: Our results present an interactive feedback loop between hormonal signaling and transport by which small biases in hormonal input are propagated into distinct signaling domains to specify the vascular pattern in the root meristem. It is an intriguing possibility that such a mechanism could transform radial patterns and allow continuous vascular connections between other newly emerging organs.}, author = {Bishopp, Anthony and Help, Hanna and El-Showk, Sedeer and Weijers, Dolf and Scheres, Ben and Jirí Friml and Eva Benková and Mähönen, Ari Pekka and Helariutta, Ykä}, journal = {Current Biology}, number = {11}, pages = {917 -- 926}, publisher = {Cell Press}, title = {{A mutually inhibitory interaction between auxin and cytokinin specifies vascular pattern in roots}}, doi = {10.1016/j.cub.2011.04.017}, volume = {21}, year = {2011}, } @article{3089, abstract = {The phytohormone auxin is an important determinant of plant development. Directional auxin flow within tissues depends on polar localization of PIN auxin transporters. To explore regulation of PIN-mediated auxin transport, we screened for suppressors of PIN1 overexpression (supo) and identified an inositol polyphosphate 1-phosphatase mutant (supo1), with elevated inositol trisphosphate (InsP 3) and cytosolic Ca 2+ levels. Pharmacological and genetic increases in InsP 3 or Ca 2+ levels also suppressed the PIN1 gain-of-function phenotypes and caused defects in basal PIN localization, auxin transport and auxin-mediated development. In contrast, the reductions in InsP 3 levels and Ca 2+ signaling antagonized the effects of the supo1 mutation and disrupted preferentially apical PIN localization. InsP 3 and Ca 2+ are evolutionarily conserved second messengers involved in various cellular functions, particularly stress responses. Our findings implicate them as modifiers of cell polarity and polar auxin transport, and highlight a potential integration point through which Ca 2+ signaling-related stimuli could influence auxin-mediated development.}, author = {Zhang, Jing and Vanneste, Steffen and Brewer, Philip B and Michniewicz, Marta and Peter Grones and Kleine-Vehn, Jürgen and Löfke, Christian and Teichmann, Thomas and Bielach, Agnieszka and Cannoot, Bernard and Hoyerová, Klára and Xu Chen and Xue, Hong-Wei and Eva Benková and Zažímalová, Eva and Jirí Friml}, journal = {Developmental Cell}, number = {6}, pages = {855 -- 866}, publisher = {Cell Press}, title = {{Inositol trisphosphate-induced ca^2+ signaling modulates auxin transport and pin polarity}}, doi = {10.1016/j.devcel.2011.05.013}, volume = {20}, year = {2011}, } @article{3090, abstract = {The polarized transport of the phytohormone auxin [1], which is crucial for the regulation of different stages of plant development [2, 3], depends on the asymmetric plasma membrane distribution of the PIN-FORMED (PIN) auxin efflux carriers [4, 5]. The PIN polar localization results from clathrin-mediated endocytosis (CME) from the plasma membrane and subsequent polar recycling [6]. The Arabidopsis genome encodes two groups of dynamin-related proteins (DRPs) that show homology to mammalian dynamin - a protein required for fission of endocytic vesicles during CME [7, 8]. Here we show by coimmunoprecipitation (coIP), bimolecular fluorescence complementation (BiFC), and Förster resonance energy transfer (FRET) that members of the DRP1 group closely associate with PIN proteins at the cell plate. Localization and phenotypic analysis of novel drp1 mutants revealed a requirement for DRP1 function in correct PIN distribution and in auxin-mediated development. We propose that rapid and specific internalization of PIN proteins mediated by the DRP1 proteins and the associated CME machinery from the cell plate membranes during cytokinesis is an important mechanism for proper polar PIN positioning in interphase cells.}, author = {Mravec, Jozef and Petrášek, Jan and Li, Na and Boeren, Sjef and Karlova, Rumyana and Kitakura, Saeko and Pařezová, Markéta and Naramoto, Satoshi and Nodzyński, Thomasz and Dhonukshe, Pankaj and Bednarek, Sebastian Y and Zažímalová, Eva and De Vries, Sacco and Jirí Friml}, journal = {Current Biology}, number = {12}, pages = {1055 -- 1060}, publisher = {Cell Press}, title = {{Cell plate restricted association of DRP1A and PIN proteins is required for cell polarity establishment in arabidopsis}}, doi = {10.1016/j.cub.2011.05.018}, volume = {21}, year = {2011}, } @article{3091, author = {Sauer, Michael and Friml, Jirí}, journal = {Molecular Systems Biology}, publisher = {Nature Publishing Group}, title = {{Fleeting hormone cues get stabilized for plant organogenesis}}, doi = {10.1038/msb.2011.45}, volume = {7}, year = {2011}, } @article{3092, abstract = {The phytohormone auxin is vital to plant growth and development. A unique property of auxin among all other plant hormones is its cell-to-cell polar transport that requires activity of polarly localized PIN-FORMED (PIN) auxin efflux transporters. Despite the substantial molecular insight into the cellular PIN polarization, the mechanistic understanding for developmentally and environmentally regulated PIN polarization is scarce. The long-standing belief that auxin modulates its own transport by means of a positive feedback mechanism has inspired both experimentalists and theoreticians for more than two decades. Recently, theoretical models for auxin-dependent patterning in plants include the feedback between auxin transport and the PIN protein localization. These computer models aid to assess the complexity of plant development by testing and predicting plausible scenarios for various developmental processes that occur in planta. Although the majority of these models rely on purely heuristic principles, the most recent mechanistic models tentatively integrate biologically testable components into known cellular processes that underlie the PIN polarity regulation. The existing and emerging computational approaches to describe PIN polarization are presented and discussed in the light of recent experimental data on the PIN polar targeting.}, author = {Wabnik, Krzysztof T and Govaerts, Willy and Friml, Jirí and Kleine Vehn, Jürgen}, journal = {Molecular BioSystems}, number = {8}, pages = {2352 -- 2359}, publisher = {Royal Society of Chemistry}, title = {{Feedback models for polarized auxin transport: An emerging trend}}, doi = {10.1039/c1mb05109a}, volume = {7}, year = {2011}, } @article{3093, abstract = { Plants take up iron from the soil using the IRON-REGULATED TRANSPORTER 1 (IRT1) high-affinity iron transporter at the root surface. Sophisticated regulatory mechanisms allow plants to tightly control the levels of IRT1, ensuring optimal absorption of essential but toxic iron. Here, we demonstrate that overexpression of Arabidopsis thaliana IRT1 leads to constitutive IRT1 protein accumulation, metal overload, and oxidative stress. IRT1 is unexpectedly found in trans-Golgi network/early endosomes of root hair cells, and its levels and localization are unaffected by iron nutrition. Using pharmacological approaches, we show that IRT1 cycles to the plasma membrane to perform iron and metal uptake at the cell surface and is sent to the vacuole for proper turnover. We also prove that IRT1 is monoubiquitinated on several cytosol-exposed residues in vivo and that mutation of two putative monoubiquitination target residues in IRT1 triggers stabilization at the plasma membrane and leads to extreme lethality. Together, these data suggest a model in which monoubiquitin-dependent internalization/sorting and turnover keep the plasma membrane pool of IRT1 low to ensure proper iron uptake and to prevent metal toxicity. More generally, our work demonstrates the existence of monoubiquitin-dependent trafficking to lytic vacuoles in plants and points to proteasome-independent turnover of plasma membrane proteins.}, author = {Barberon, Marie and Zelazny, Enric and Robert, Stéphanie and Conéjéro, Geneviève and Curie, Cathy and Jirí Friml and Vert, Grégory}, journal = {PNAS}, number = {32}, pages = {E450 -- E458}, publisher = {National Academy of Sciences}, title = {{Monoubiquitin dependent endocytosis of the Iron Regulated Transporter 1 IRT1 transporter controls iron uptake in plants}}, doi = {10.1073/pnas.1100659108}, volume = {108}, year = {2011}, } @article{3094, abstract = {Summary Gravitropism aligns plant growth with gravity. It involves gravity perception and the asymmetric distribution of the phytohormone auxin. Here we provide insights into the mechanism for hypocotyl gravitropic growth. We show that the Arabidopsis thaliana PIN3 auxin transporter is required for the asymmetric auxin distribution for the gravitropic response. Gravistimulation polarizes PIN3 to the bottom side of hypocotyl endodermal cells, which correlates with an increased auxin response at the lower hypocotyl side. Both PIN3 polarization and hypocotyl bending require the activity of the trafficking regulator GNOM and the protein kinase PINOID. Our data suggest that gravity-induced PIN3 polarization diverts the auxin flow to mediate the asymmetric distribution of auxin for gravitropic shoot bending.}, author = {Rakusová, Hana and Gallego-Bartolomé, Javier and Vanstraelen, Marleen and Robert, Hélène S and Alabadí, David and Blázquez, Miguel A and Eva Benková and Jirí Friml}, journal = {Plant Journal}, number = {5}, pages = {817 -- 826}, publisher = {Wiley-Blackwell}, title = {{Polarization of PIN3 dependent auxin transport for hypocotyl gravitropic response in Arabidopsis thaliana}}, doi = {10.1111/j.1365-313X.2011.04636.x}, volume = {67}, year = {2011}, } @article{3095, abstract = {Root system architecture depends on lateral root (LR) initiation that takes place in a relatively narrow developmental window (DW). Here, we analyzed the role of auxin gradients established along the parent root in defining this DW for LR initiation. Correlations between auxin distribution and response, and spatiotemporal control of LR initiation were analyzed in Arabidopsis thaliana and tomato (Solanum lycopersicum). In both Arabidopsis and tomato roots, a well defined zone, where auxin content and response are minimal, demarcates the position of a DW for founder cell specification and LR initiation. We show that in the zone of auxin minimum pericycle cells have highest probability to become founder cells and that auxin perception via the TIR1/AFB pathway, and polar auxin transport, are essential for the establishment of this zone. Altogether, this study reveals that the same morphogen-like molecule, auxin, can act simultaneously as a morphogenetic trigger of LR founder cell identity and as a gradient-dependent signal defining positioning of the founder cell specification. This auxin minimum zone might represent an important control mechanism ensuring the LR initiation steadiness and the acropetal LR initiation pattern. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.}, author = {Dubrovsky, Joseph G and Napsucialy-Mendivil, Selene and Duclercq, Jérôme and Cheng, Yan and Shishkova, Svetlana O and Ivanchenko, Maria G and Jirí Friml and Murphy, Angus S and Eva Benková}, journal = {New Phytologist}, number = {4}, pages = {970 -- 983}, publisher = {Wiley-Blackwell}, title = {{Auxin minimum defines a developmental window for lateral root initiation}}, doi = { 10.1111/j.1469-8137.2011.03757.x}, volume = {191}, year = {2011}, } @article{3096, abstract = {Carrier-dependent, intercellular auxin transport is central to the developmental patterning of higher plants (tracheophytes). The evolution of this polar auxin transport might be linked to the translocation of some PIN auxin efflux carriers from their presumably ancestral localization at the endoplasmic reticulum (ER) to the polar domains at the plasma membrane. Here we propose an eventually ancient mechanism of intercellular auxin distribution by ER-localized auxin transporters involving intracellular auxin retention and switch-like release from the ER. The proposed model integrates feedback circuits utilizing the conserved nuclear auxin signaling for the regulation of PIN transcription and a hypothetical ER-based signaling for the regulation of PIN-dependent transport activity at the ER. Computer simulations of the model revealed its plausibility for generating auxin channels and localized auxin maxima highlighting the possibility of this alternative mechanism for polar auxin transport.}, author = {Wabnik, Krzysztof T and Kleine Vehn, Jürgen and Govaerts, Willy and Friml, Jirí}, journal = {Trends in Plant Science}, number = {9}, pages = {468 -- 475}, publisher = {Cell Press}, title = {{Prototype cell-to-cell auxin transport mechanism by intracellular auxin compartmentalization}}, doi = {10.1016/j.tplants.2011.05.002}, volume = {16}, year = {2011}, } @article{3097, abstract = {Cytokinin is an important regulator of plant growth and development. In Arabidopsis thaliana, the two-component phosphorelay mediated through a family of histidine kinases and response regulators is recognized as the principal cytokinin signal transduction mechanism activating the complex transcriptional response to control various developmental processes. Here, we identified an alternative mode of cytokinin action that uses endocytic trafficking as a means to direct plant organogenesis. This activity occurs downstream of known cytokinin receptors but through a branch of the cytokinin signaling pathway that does not involve transcriptional regulation. We show that cytokinin regulates endocytic recycling of the auxin efflux carrier PINFORMED1 (PIN1) by redirecting it for lytic degradation in vacuoles. Stimulation of the lytic PIN1 degradation is not a default effect for general downregulation of proteins from plasma membranes, but a specific mechanism to rapidly modulate the auxin distribution in cytokinin-mediated developmental processes.}, author = {Peter Marhavy and Bielach, Agnieszka and Abas, Lindy and Abuzeineh, Anas and Duclercq, Jérôme and Tanaka, Hirokazu and Pařezová, Markéta and Petrášek, Jan and Jirí Friml and Kleine-Vehn, Jürgen and Eva Benková}, journal = {Developmental Cell}, number = {4}, pages = {796 -- 804}, publisher = {Cell Press}, title = {{Cytokinin modulates endocytic trafficking of PIN1 auxin efflux carrier to control plant organogenesis}}, doi = {10.1016/j.devcel.2011.08.014}, volume = {21}, year = {2011}, } @article{3098, abstract = {Cell polarity reflected by asymmetric distribution of proteins at the plasma membrane is a fundamental feature of unicellular and multicellular organisms. It remains conceptually unclear how cell polarity is kept in cell wall-encapsulated plant cells. We have used super-resolution and semi-quantitative live-cell imaging in combination with pharmacological, genetic, and computational approaches to reveal insights into the mechanism of cell polarity maintenance in Arabidopsis thaliana. We show that polar-competent PIN transporters for the phytohormone auxin are delivered to the center of polar domains by super-polar recycling. Within the plasma membrane, PINs are recruited into non-mobile membrane clusters and their lateral diffusion is dramatically reduced, which ensures longer polar retention. At the circumventing edges of the polar domain, spatially defined internalization of escaped cargos occurs by clathrin-dependent endocytosis. Computer simulations confirm that the combination of these processes provides a robust mechanism for polarity maintenance in plant cells. Moreover, our study suggests that the regulation of lateral diffusion and spatially defined endocytosis, but not super-polar exocytosis have primary importance for PIN polarity maintenance.}, author = {Kleine-Vehn, Jürgen and Krzysztof Wabnik and Martinière, Alexandre and Łangowski, Łukasz and Willig, Katrin and Naramoto, Satoshi and Leitner, Johannes and Tanaka, Hirokazu and Jakobs, Stefan and Robert, Stéphanie and Luschnig, Christian and Govaerts, Willy J and Hell, Stefan W and Runions, John and Jirí Friml}, journal = {Molecular Systems Biology}, publisher = {Nature Publishing Group}, title = {{Recycling, clustering and endocytosis jointly maintain PIN auxin carrier polarity at the plasma membrane}}, doi = {10.1038/msb.2011.72}, volume = {7}, year = {2011}, }