@article{2761, abstract = {We consider N × N Hermitian random matrices with independent identically distributed entries (Wigner matrices). We assume that the distribution of the entries have a Gaussian component with variance N 3/4+β for some positive β > 0. We prove that the local eigenvalue statistics follows the universal Dyson sine kernel.}, author = {László Erdös and Ramírez, José A and Schlein, Benjamin and Yau, Horng-Tzer}, journal = {Electronic Journal of Probability}, number = {18}, pages = {526 -- 603}, publisher = {Institute of Mathematical Statistics}, title = {{Universality of sine-kernel for Wigner matrices with a small Gaussian perturbation}}, doi = {10.1214/EJP.v15-768}, volume = {15}, year = {2010}, } @article{2762, abstract = {We consider N ×N Hermitian Wigner random matrices H where the probabilitydensity for each matrix element is given by the density v(x)=e-U(x). We prove that the eigenvalue statistics in the bulk are given by the Dyson sine kernel provided that U ∈ C 6(R{double-struck}) with at most polynomially growing derivatives and v(x)≤C e-c(x) for x large. The proof is based upon an approximate time reversal of the Dyson Brownian motion combined with the convergence of the eigenvalue density to the Wigner semicircle law on short scales.}, author = {László Erdös and Ramírez, José A and Yau, Horng-Tzer and Péché, Sandrine and Schlein, Benjamin}, journal = {Communications on Pure and Applied Mathematics}, number = {7}, pages = {895 -- 925}, publisher = {Wiley-Blackwell}, title = {{Bulk universality for Wigner matrices}}, doi = {10.1002/cpa.20317}, volume = {63}, year = {2010}, } @article{2763, abstract = {In this paper, we consider the ensemble of n×n Wigner Hermitian matrices H = (hℓk)1≤ℓ,k≤n that generalize the Gaussian unitary ensemble (GUE). The matrix elements hℓk = h̄ℓk are given by hℓk = n ?1/2(xℓk + √?1yℓk), where xℓk, yℓk for 1 ≤ ℓ < k ≤ n are i.i.d. random variables with mean zero and variance 1/2, yℓ ℓ = 0 and xℓ ℓ have mean zero and variance 1. We assume the distribution of xℓk, yℓk to have subexponential decay. In [3], four of the authors recently established that the gap distribution and averaged k-point correlation of these matrices were universal (and in particular, agreed with those for GUE) assuming additional regularity hypotheses on the xℓk, yℓk. In [7], the other two authors, using a different method, established the same conclusion assuming instead some moment and support conditions on the xℓk, yℓk. In this short note we observe that the arguments of [3] and [7] can be combined to establish universality of the gap distribution and averaged k-point correlations for all Wigner matrices (with subexponentially decaying entries), with no extra assumptions.}, author = {László Erdös and Ramírez, José A and Schlein, Benjamin and Tao, Terence and Van, Vu and Yau, Horng-Tzer}, journal = {Mathematical Research Letters}, number = {4}, pages = {667 -- 674}, publisher = {International Press}, title = {{Bulk universality for Wigner Hermitian matrices with subexponential decay}}, volume = {17}, year = {2010}, } @article{2798, abstract = {Flows through pipes and channels are the most common means to transport fluids in practical applications and equally occur in numerous natural systems. In general, the transfer of fluids is energetically far more efficient if the motion is smooth and laminar because the friction losses are lower. However, even at moderate velocities pipe and channel flows are sensitive to minute disturbances, and in practice most flows are turbulent. Investigating the motion and spatial distribution of vortices, we uncovered an amplification mechanism that constantly feeds energy from the mean shear into turbulent eddies. At intermediate flow rates, a simple control mechanism suffices to intercept this energy transfer by reducing inflection points in the velocity profile. When activated, an immediate collapse of turbulence is observed, and the flow relaminarizes.}, author = {Björn Hof and de Lózar, Alberto and Avila, Marc and Xiaoyun Tu and Schneider, Tobias M}, journal = {Science}, number = {5972}, pages = {1491 -- 1494}, publisher = {American Association for the Advancement of Science}, title = {{Eliminating turbulence in spatially intermittent flows}}, doi = {10.1126/science.1186091}, volume = {327}, year = {2010}, } @article{2870, abstract = {Dark-grown dicotyledonous seedlings form a hook-like structure at the top of the hypocotyl, which is controlled by the hormones auxin and ethylene. Hook formation is dependent on an auxin signal gradient, whereas hook exaggeration is part of the triple response provoked by ethylene in dark-grown Arabidopsis seedlings. Several other hormones and light are also known to be involved in hook development, but the molecular mechanisms that lead to the initial installation of an auxin gradient are still poorly understood. In this study, we aimed to unravel the cross-talk between auxin and ethylene in the apical hook. Auxin measurements, the expression pattern of the auxin reporter DR5::GUS and the localization of auxin biosynthesis enzymes and influx carriers collectively indicate the necessity for auxin biosynthesis and efficient auxin translocation from the cotyledons and meristem into the hypocotyl in order to support proper hook development. Auxin accumulation in the meristem and cotyledons and in the hypocotyl is increased ∼2-fold upon treatment with ethylene. In addition, a strong ethylene signal leads to enhanced auxin biosynthesis at the inner side of the hook. Finally, mutant analysis demonstrates that the auxin influx carrier LAX3 is indispensable for proper hook formation, whereas the auxin influx carrier AUX1 is involved in the hook exaggeration phenotype induced by ethylene.}, author = {Vandenbussche, Filip and Petrášek, Jan and Žádníková, Petra and Hoyerová, Klára and Pešek, Bedřich and Raz, Vered and Swarup, Ranjan and Bennett, Malcolm and Zažímalová, Eva and Eva Benková and Van Der Straeten, Dominique}, journal = {Development}, number = {4}, pages = {597 -- 606}, publisher = {Company of Biologists}, title = {{The auxin influx carriers AUX1 and LAX3 are involved in auxin-ethylene interactions during apical hook development in Arabidopsis thaliana seedlings}}, doi = {10.1242/dev.040790}, volume = {137}, year = {2010}, } @article{2872, abstract = {Unlike locomotive organisms capable of actively approaching essential resources, sessile plants must efficiently exploit their habitat for water and nutrients. This involves root-mediated underground interactions allowing plants to adapt to soils of diverse qualities. The root system of plants is a dynamic structure that modulates primary root growth and root branching by continuous integration of environmental inputs, such as nutrition availability, soil aeration, humidity, or salinity. Root branching is an extremely flexible means to rapidly adjust the overall surface of the root system and plants have evolved efficient control mechanisms, including, firstly initiation, when and where to start lateral root formation; secondly lateral root primordia organogenesis, during which the development of primordia can be arrested for a certain time; and thirdly lateral root emergence. Our review will focus on the most recent advances in understanding the molecular mechanisms involved in the regulation of lateral root initiation and organogenesis with the main focus on root system of the model plant Arabidopsis thaliana.}, author = {Eva Benková and Bielach, Agnieszka}, journal = {Current Opinion in Plant Biology}, number = {6}, pages = {677 -- 683}, publisher = {Elsevier}, title = {{Lateral root organogenesis - from cell to organ}}, doi = {10.1016/j.pbi.2010.09.006}, volume = {13}, year = {2010}, } @article{2873, abstract = {Nitrate is both a nitrogen source for higher plants and a signal molecule regulating their development. In Arabidopsis, the NRT1.1 nitrate transporter is crucial for nitrate signaling governing root growth, and has been proposed to act as a nitrate sensor. However, the sensing mechanism is unknown. Herein we show that NRT1.1 not only transports nitrate but also facilitates uptake of the phytohormone auxin. Moreover, nitrate inhibits NRT1.1-dependent auxin uptake, suggesting that transduction of nitrate signal by NRT1.1 is associated with a modification of auxin transport. Among other effects, auxin stimulates lateral root development. Mutation of NRT1.1 enhances both auxin accumulation in lateral roots and growth of these roots at low, but not high, nitrate concentration. Thus, we propose that NRT1.1 represses lateral root growth at low nitrate availability by promoting basipetal auxin transport out of these roots. This defines a mechanism connecting nutrient and hormone signaling during organ development.}, author = {Krouk, Gabriel and Lacombe, Benoît and Bielach, Agnieszka and Perrine-Walker, Francine and Malínská, Kateřina and Mounier, Emmanuelle and Hoyerová, Klára and Tillard, Pascal and Leon, Sarah and Ljung, Karin and Zažímalová, Eva and Eva Benková and Nacry, Philippe and Gojon, Alain}, journal = {Developmental Cell}, number = {6}, pages = {927 -- 937}, publisher = {Cell Press}, title = {{Nitrate-regulated auxin transport by NRT1.1 defines a mechanism for nutrient sensing in plants}}, doi = {10.1016/j.devcel.2010.05.008}, volume = {18}, year = {2010}, } @article{2899, abstract = {Toxin–antitoxin (TA) systems are commonly found on bacterial plasmids. The antitoxin inhibits toxin activity unless the system is lost from the cell. Then the shorter lived antitoxin degrades and the cell becomes susceptible to the toxin. Selection for plasmid-encoded TA systems was initially thought to result from their reducing the number of plasmid-free cells arising during growth in monoculture. However, modelling and experiments have shown that this mechanism can only explain the success of plasmid TA systems under a restricted set of conditions. Previously, we have proposed and tested an alternative model explaining the success of plasmid TA systems as a consequence of competition occurring between plasmids during co-infection of bacterial hosts. Here, we test a further prediction of this model, that competition between plasmids will lead to the biased accumulation of TA systems on plasmids relative to chromosomes. Transposon-encoded TA systems were added to populations of plasmid-containing cells, such that TA systems could insert into either plasmids or chromosomes. These populations were enriched for transposon-containing cells and then incubated in environments that did, or did not, allow effective within-host plasmid competition to occur. Changes in the ratio of plasmid- to chromosome-encoded TA systems were monitored. In agreement with our model, we found that plasmid-encoded TA systems had a competitive advantage, but only when host cells were sensitive to the effect of TA systems. This result demonstrates that within-host competition between plasmids can select for TA systems.}, author = {Cooper, Tim F and Tiago Paixao and Heinemann, Jack A}, journal = {Proc R Soc B}, number = {1697}, pages = {3149 -- 3155}, publisher = {Wiley-Blackwell}, title = {{Within host competition selects for plasmid encoded toxin–antitoxin systems}}, doi = {10.1098/rspb.2010.0831}, volume = {277}, year = {2010}, } @inproceedings{2934, author = {Vladimir Kolmogorov}, publisher = {Neural Information Processing Systems}, title = {{Generalized roof duality and bisubmodular functions}}, year = {2010}, } @inproceedings{2978, abstract = {Efficient zero-knowledge proofs of knowledge for group homomorphisms are essential for numerous systems in applied cryptography. Especially, Σ-protocols for proving knowledge of discrete logarithms in known and hidden order groups are of prime importance. Yet, while these proofs can be performed very efficiently within groups of known order, for hidden order groups the respective proofs are far less efficient. This paper shows strong evidence that this efficiency gap cannot be bridged. Namely, while there are efficient protocols allowing a prover to cheat only with negligibly small probability in the case of known order groups, we provide strong evidence that for hidden order groups this probability is bounded below by 1/2 for all efficient Σ-protocols not using common reference strings or the like. We prove our results for a comprehensive class of Σ-protocols in the generic group model, and further strengthen them by investigating certain instantiations in the plain model.}, author = {Bangerter, Endre and Camenisch, Jan and Stephan Krenn}, editor = {Micciancio, Daniele}, pages = {553 -- 571}, publisher = {Springer}, title = {{Efficiency Limitations for Σ-Protocols for Group Homomorphisms}}, doi = {10.1007/978-3-642-11799-2}, volume = {5978}, year = {2010}, } @inproceedings{2979, abstract = {Zero-knowledge proofs of knowledge (ZK-PoK) are important building blocks for numerous cryptographic applications. Although ZK-PoK have a high potential impact, their real world deployment is typically hindered by their significant complexity compared to other (non-interactive) crypto primitives. Moreover, their design and implementation are time-consuming and error-prone. We contribute to overcoming these challenges as follows: We present a comprehensive specification language and a compiler for ZK-PoK protocols based on Σ-protocols. The compiler allows the fully automatic translation of an abstract description of a proof goal into an executable implementation. Moreover, the compiler overcomes various restrictions of previous approaches, e.g., it supports the important class of exponentiation homomorphisms with hidden-order co-domain, needed for privacy-preserving applications such as DAA. Finally, our compiler is certifying, in the sense that it automatically produces a formal proof of the soundness of the compiled protocol for a large class of protocols using the Isabelle/HOL theorem prover. }, author = {Almeida, José Bacelar and Bangerter, Endre and Barbosa, Manuel and Stephan Krenn and Sadeghi, Ahmad-Reza and Schneider, Thomas}, editor = {Gritzalis, Dimitris and Preneel, Bart and Theoharidou, Marianthi}, pages = {151 -- 167}, publisher = {Springer}, title = {{A Certifying Compiler for Zero-Knowledge Proofs of Knowledge Based on Sigma-Protocols}}, doi = {10.1007/978-3-642-15497-3}, volume = {6345}, year = {2010}, } @inproceedings{2980, abstract = {Efficient zero-knowledge proofs of knowledge (ZK-PoK) are basic building blocks of many practical cryptographic applications such as identification schemes, group signatures, and secure multi-party computation (SMPC). Currently, first applications that essentially rely on ZK-PoKs are being deployed in the real world. The most prominent example is the Direct Anonymous Attestation (DAA) protocol, which was adopted by the Trusted Computing Group (TCG) and implemented as one of the functionalities of the cryptographic chip Trusted Platform Module (TPM). Implementing systems using ZK-PoK turns out to be challenging, since ZK-PoK are significantly more complex than standard crypto primitives (e.g., encryption and signature schemes). As a result, the design-implementation cycles of ZK-PoK are time-consuming and error-prone. To overcome this, we present a compiler with corresponding languages for the automatic generation of sound and efficient ZK-PoK based on Σ-protocols. The protocol designer using our compiler formulates the goal of a ZK-PoK proof in a high-level protocol specification language, which abstracts away unnecessary technicalities from the designer. The compiler then automatically generates the protocol implementation in Java code; alternatively, the compiler can output a description of the protocol in LaTeX which can be used for documentation or verification.}, author = {Bangerter, Endre and Briner, Thomas and Henecka, Wilko and Stephan Krenn and Sadeghi, Ahmad-Reza and Schneider, Thomas}, editor = {Martinelli, Fabio and Preneel, Bart}, pages = {67 -- 82}, publisher = {Springer}, title = {{Automatic Generation of Sigma-Protocols}}, doi = {10.1007/978-3-642-16441-5}, volume = {6391}, year = {2010}, } @article{3062, abstract = {Development in multicellular organisms depends on the ability of individual cells to coordinate their behavior by means of small signaling molecules to form correctly patterned tissues. In plants, a unique mechanism of directional transport of the signaling molecule auxin between cells connects cell polarity and tissue patterning and thus is required for many aspects of plant development. Direction of auxin flow is determined by polar subcellular localization of PIN auxin efflux transporters. Dynamic PIN polar localization results from the constitutive endocytic cycling to and from the plasma membrane, but it is not well understood how this mechanism connects to regulators of cell polarity. The Rho family small GTPases ROPs/RACs are master regulators of cell polarity, however their role in regulating polar protein trafficking and polar auxin transport has not been established. Here, by analysis of mutants and transgenic plants, we show that the ROP interactor and polarity regulator scaffold protein ICR1 is required for recruitment of PIN proteins to the polar domains at the plasma membrane. icr1 mutant embryos and plants display an a array of severe developmental aberrations that are caused by compromised differential auxin distribution. ICR1 functions at the plasma membrane where it is required for exocytosis but does not recycle together with PINs. ICR1 expression is quickly induced by auxin but is suppressed at the positions of stable auxin maxima in the hypophysis and later in the embryonic and mature root meristems. Our results imply that ICR1 is part of an auxin regulated positive feedback loop realized by a unique integration of auxin-dependent transcriptional regulation into ROP-mediated modulation of cell polarity. Thus, ICR1 forms an auxin-modulated link between cell polarity, exocytosis, and auxin transport-dependent tissue patterning.}, author = {Hazak, Ora and Bloch, Daria and Poraty, Limor and Sternberg, Hasana and Zhang, Jing and Jirí Friml and Yalovsky, Shaul}, journal = {PLoS Biology}, number = {1}, publisher = {Public Library of Science}, title = {{A Rho scaffold integrates the secretory system with feedback mechanisms in regulation of auxin distribution}}, doi = {10.1371/journal.pbio.1000282}, volume = {8}, year = {2010}, } @article{3063, abstract = {The directional transport of the plant hormone auxin is a unique process mediating a wide variety of developmental processes. Auxin movement between cells depends on AUX1/LAX, PGP and PIN protein families that mediate auxin transport across the plasma membrane. The directionality of auxin flow within tissues is largely determined by polar, subcellular localization of PIN auxin efflux carriers. PIN proteins undergo rapid subcellular dynamics that is important for the process of auxin transport and its directionality. Furthermore, various environmental and endogenous signals can modulate trafficking and polarity of PIN proteins and by this mechanism change auxin distribution. Thus, the subcellular dynamics of auxin transport proteins represents an important interface between cellular processes and development of the whole plant. This review summarizes our recent contributions to the field of PIN trafficking and auxin transport regulation. © 2009 Elsevier GmbH.}, author = {Jirí Friml}, journal = {European Journal of Cell Biology}, number = {2-3}, pages = {231 -- 235}, publisher = {Elsevier}, title = {{Subcellular trafficking of PIN auxin efflux carriers in auxin transport}}, doi = {10.1016/j.ejcb.2009.11.003}, volume = {89}, year = {2010}, } @article{3064, abstract = {The plant hormone auxin plays a crucial role in regulating plant development and plant architecture. The directional auxin distribution within tissues depends on PIN transporters that are polarly localized on the plasmamembrane. The PINpolarity and the resulting auxin flow directionality aremediated by the antagonistic actions of PINOID kinase and protein phosphatase 2A. However, the contributionof the PINphosphorylationto the polar PINsortingis still unclear. Here, we identified an evolutionarily conserved phosphorylation site within the central hydrophilic loop of PIN proteins that is important for the apical and basal polar PIN localizations. Inactivation of the phosphorylation site in PIN1(Ala) resulted in a predominantly basal targeting and increased the auxinflowto the root tip. In contrast, the outcome of the phosphomimic PIN1(Asp) manipulation was a constitutive, PINOID-independent apical targeting of PIN1 and an increased auxin flow in the opposite direction. Furthermore, the PIN1(Asp) functionally replaced PIN2 in its endogenous expression domain, revealing that the phosphorylation-dependent polarity regulation contributes to functional diversification within the PIN family. Our data suggest that PINOID-independent PIN phosphorylation at one single site is adequate to change the PIN polarity and, consequently, to redirect auxin fluxes between cells and provide the conceptual possibility and means to manipulate auxin-dependent plant development and architecture.}, author = {Zhang, Jing and Nodzyński, Thomasz and Pěnčík, Aleš and Rolčík, Jakub and Jirí Friml}, journal = {PNAS}, number = {2}, pages = {918 -- 922}, publisher = {National Academy of Sciences}, title = {{PIN phosphorylation is sufficient to mediate PIN polarity and direct auxin transport}}, doi = {10.1073/pnas.0909460107}, volume = {107}, year = {2010}, } @article{3065, abstract = {The apical hook of dark-grown Arabidopsis seedlings is a simple structure that develops soon after germination to protect the meristem tissues during emergence through the soil and that opens upon exposure to light. Differential growth at the apical hook proceeds in three sequential steps that are regulated by multiple hormones, principally auxin and ethylene. We show that the progress of the apical hook through these developmental phases depends on the dynamic, asymmetric distribution of auxin, which is regulated by auxin efflux carriers of the PIN family. Several PIN proteins exhibited specific, partially overlapping spatial and temporal expression patterns, and their subcellular localization suggested auxin fluxes during hook development. Genetic manipulation of individual PIN activities interfered with different stages of hook development, implying that specific combinations of PIN genes are required for progress of the apical hook through the developmental phases. Furthermore, ethylene might modulate apical hook development by prolonging the formation phase and strongly suppressing the maintenance phase. This ethylene effect is in part mediated by regulation of PIN-dependent auxin efflux and auxin signaling.}, author = {Žádníková, Petra and Petrášek, Jan and Peter Marhavy and Raz, Vered and Vandenbussche, Filip and Ding, Zhaojun and Schwarzerová, Kateřina and Morita, Miyo T and Tasaka, Masao and Hejátko, Jan and Van Der Straeten, Dominique and Jirí Friml and Eva Benková}, journal = {Development}, number = {4}, pages = {607 -- 617}, publisher = {Company of Biologists}, title = {{Role of PIN-mediated auxin efflux in apical hook development of Arabidopsis thaliana}}, doi = {10.1242/dev.041277}, volume = {137}, year = {2010}, } @article{3066, abstract = {In animals, the interface between organism and environment is constituted by the epithelium [1]. In plants, the exchange of nutrients and signals between root and soil is crucial for their survival, but the cellular mechanisms underlying the epithelium-like function and specific localization of proteins to the root surface have not been identified [2]. Here we analyze the mechanism of polar delivery to the root-soil interface of the proteins BOR4, ABCG37, and PEN3, which transport nutrients [2], transport plant hormones, and are required for pathogen defense [3], respectively. The simultaneous visualization of these proteins and the apical and basal cargos in a single cell demonstrates that the outermost cell side represents an additional polar domain. Delivery to this outer polar domain depends on ARF GEF [4] and actin [5-8] function but does not require known molecular components of the apical or basal targeting. The outer polar delivery is, in contrast to known basal and apical cargos [9, 10], mediated by the polar secretion. Our findings show that the outermost cell membranes of roots define an additional polar domain in plant cells along with a specific, previously uncharacterized, polar targeting mechanism that is important for defining the functional, epithelium-like root-soil interface.}, author = {Łangowski, Łukasz and Růžička, Kamil and Naramoto, Satoshi and Kleine-Vehn, Jürgen and Jirí Friml}, journal = {Current Biology}, number = {10}, pages = {904 -- 908}, publisher = {Cell Press}, title = {{Trafficking to the outer polar domain defines the root soil interface}}, doi = {10.1016/j.cub.2010.03.059}, volume = {20}, year = {2010}, } @article{3067, abstract = {Remarkable progress in various techniques of in vivo fluorescence microscopy has brought an urgent need for reliable markers for tracking cellular structures and processes. The goal of this manuscript is to describe unexplored effects of the FM (Fei Mao) styryl dyes, which are widely used probes that label processes of endocytosis and vesicle trafficking in eukaryotic cells. Although there are few reports on the effect of styryl dyes on membrane fluidity and the activity of mammalian receptors, FM dyes have been considered as reliable tools for tracking of plant endocytosis. Using plasma membrane-localized transporters for the plant hormone auxin in tobacco BY-2 and Arabidopsis thaliana cell suspensions, we show that routinely used concentrations of FM 4-64 and FM 5-95 trigger transient re-localization of these proteins, and FM 1-43 affects their activity. The active process of re-localization is blocked neither by inhibitors of endocytosis nor by cytoskeletal drugs. It does not occur in A. thaliana roots and depends on the degree of hydrophobicity (lipophilicity) of a particular FM dye. Our results emphasize the need for circumspection during in vivo studies of membrane proteins performed using simultaneous labelling with FM dyes.}, author = {Jelínková, Adriana and Malínská, Kateřina and Sibu Simon and Kleine-Vehn, Jürgen and Pařezová, Markéta and Pejchar, Přemysl and Kubeš, Martin and Martinec, Jan and Jirí Friml and Zažímalová, Eva and Petrášek, Jan}, journal = {Plant Journal}, number = {5}, pages = {883 -- 892}, publisher = {Wiley-Blackwell}, title = {{Probing plant membranes with FM dyes: Tracking dragging or blocking?}}, doi = {10.1111/j.1365-313X.2009.04102.x}, volume = {61}, year = {2010}, } @article{3068, abstract = {Differential distribution of the plant hormone auxin within tissues mediates a variety of developmental processes. Cellular auxin levels are determined by metabolic processes including synthesis, degradation, and (de)conjugation, as well as by auxin transport across the plasma membrane. Whereas transport of free auxins such as naturally occurring indole-3-acetic acid (IAA) is well characterized, little is known about the transport of auxin precursors and metabolites. Here, we identify amutation in the ABCG37 gene of Arabidopsis that causes the polar auxin transport inhibitor sensitive1 (pis1) phenotype manifested by hypersensitivity to auxinic compounds. ABCG37 encodes the pleiotropic drug resistance transporter that transports a range of synthetic auxinic compounds as well as the endogenous auxin precursor indole-3-butyric acid (IBA), but not free IAA. ABCG37 and its homolog ABCG36 act redundantly at outermost root plasma membranes and,unlike established IAA transporters from the PIN and ABCB families, transport IBA out of the cells. Our findings explore possible novel modes of regulating auxin homeostasis and plant development by means of directional transport of the auxin precursor IBA and presumably also other auxin metabolites.}, author = {Růžička, Kamil and Strader, Lucia C and Bailly, Aurélien and Yang, Haibing and Blakeslee, Joshua and Łangowski, Łukasz and Nejedlá, Eliška and Fujita, Hironori and Itoh, Hironori and Syōno, Kunihiko and Hejátko, Jan and Gray, William M and Martinoia, Enrico and Geisler, Markus and Bartel, Bonnie and Murphy, Angus S and Jirí Friml}, journal = {PNAS}, number = {23}, pages = {10749 -- 10753}, publisher = {National Academy of Sciences}, title = {{Arabidopsis PIS1 encodes the ABCG37 transporter of auxinic compounds including the auxin precursor indole 3 butyric acid}}, doi = {10.1073/pnas.1005878107}, volume = {107}, year = {2010}, } @article{3069, abstract = {The stem cell niche in the root meristem is critical for the development of the plant root system. The plant hormone auxin acts as a versatile trigger in many developmental processes, including the regulation of root growth, but its role in the control of the stem cell activity remains largely unclear. Here we show that local auxin levels, determined by biosynthesis and intercellular transport, mediate maintenance or differentiation of distal stem cells in the Arabidopsis thaliana roots. Genetic analysis shows that auxin acts upstream of the major regulators of the stem cell activity, the homeodomain transcription factor WOX5, and the AP-2 transcription factor PLETHORA. Auxin signaling for differentiation of distal stem cells requires the transcriptional repressor IAA17/AXR3 as well as the ARF10 and ARF16 auxin response factors. ARF10 and ARF16 activities repress the WOX5 transcription and restrict it to the quiescent center, where WOX5, in turn, is needed for the activity of PLETHORA. Our investigations reveal that long-distance auxin signals act upstream of the short-range network of transcriptional factors to mediate the differentiation of distal stem cells in roots.}, author = {Ding, Zhaojun and Jirí Friml}, journal = {PNAS}, number = {26}, pages = {12046 -- 12051}, publisher = {National Academy of Sciences}, title = {{Auxin regulates distal stem cell differentiation in Arabidopsis roots}}, doi = {10.1073/pnas.1000672107}, volume = {107}, year = {2010}, }