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Auxin Transport

The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform

Jiři Friml – 1st expert on this subject based on the ideXlab platform

  • subcellular trafficking of pin Auxin efflux carriers in Auxin Transport
    European Journal of Cell Biology, 2010
    Co-Authors: Jiři Friml

    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.

  • Auxin Transport — shaping the plant
    Current Opinion in Plant Biology, 2003
    Co-Authors: Jiři Friml

    Abstract:

    Plant growth is marked by its adaptability to continuous changes in environment. A regulated, differential distribution of Auxin underlies many adaptation processes including organogenesis, meristem patterning and tropisms. In executing its multiple roles, Auxin displays some characteristics of both a hormone and a morphogen. Studies on Auxin Transport, as well as tracing the intracellular movement of its molecular components, have suggested a possible scenario to explain how growth plasticity is conferred at the cellular and molecular level. The plant perceives stimuli and changes the subcellular position of AuxinTransport components accordingly. These changes modulate Auxin fluxes, and the newly established Auxin distribution triggers the corresponding developmental response.

  • Auxin Transport – Shaping the plant
    Current Opinion in Plant Biology, 2003
    Co-Authors: Jiři Friml

    Abstract:

    Plant growth is marked by its adaptability to continuous changes in environment. A regulated, differential distribution of Auxin underlies many adaptation processes including organogenesis, meristem patterning and tropisms. In executing its multiple roles, Auxin displays some characteristics of both a hormone and a morphogen. Studies on Auxin Transport, as well as tracing the intracellular movement of its molecular components, have suggested a possible scenario to explain how growth plasticity is conferred at the cellular and molecular level. The plant perceives stimuli and changes the subcellular position of AuxinTransport components accordingly. These changes modulate Auxin fluxes, and the newly established Auxin distribution triggers the corresponding developmental response.

Gloria K Muday – 2nd expert on this subject based on the ideXlab platform

  • Interactions Between the Actin Cytoskeleton and an Auxin Transport Protein
    Actin: A Dynamic Framework for Multiple Plant Cell Functions, 2020
    Co-Authors: Gloria K Muday

    Abstract:

    In shoots, polar Auxin Transport is basipetal (i.e., from the shoot apex toward the base), and is driven by the basal localization of the Auxin efflux carrier complex. One mechanism by which this efflux carrier complex could be localized to the basal membrane is through attachment to the actin cytoskeleton. The efflux carrier protein complex is believed to consist of several polypeptides, including a regulatory subunit that binds Auxin Transport inhibitors such as naphthylphthalamic acid (NPA). Several lines of experimentation have been used to determine whether the NPA-binding protein interacts with actin filaments. The NPA-binding protein has been shown to partition with the actin cytoskeleton during detergent extraction. Agents that specifically alter the polymerization state of the actin cytoskeleton also change the amount of NPA-binding protein and actin recovered in these cytoskeletal pellets. Actin affinity columns were prepared with polymers of actin purified from zucchini hypocotyl tissue. NPA-binding activity was eluted in a single peak from the actin filament column. Cytochalasin D, which fragments the actin cytoskeleton, was shown to reduce polar Auxin Transport in zucchini hypocotyls. The interaction of the NPA-binding protein with the actin cytoskeleton may localize it in one plane of the plasma membrane, and thereby control the polarity of Auxin Transport.

  • Control of Auxin Transport by Reactive Oxygen and Nitrogen Species
    Polar Auxin Transport, 2013
    Co-Authors: María Fernández-marcos, Gloria K Muday, Luis Sanz, Daniel R. Lewis, Oscar Lorenzo

    Abstract:

    Auxin Transport is a central process in plant growth and development and as a result is highly regulated. The amount and direction of Auxin Transport is defined by a set of Auxin influx and efflux carriers with precise localization that lead to long-distance polar Auxin Transport. These Auxin Transport proteins are regulated by transcriptional and posttranslational mechanisms and through protein-targeting machinery that directs them to the appropriate plasma membrane location. A variety of signals initiate regulatory changes in the abundance, activity, or localization of these proteins, with plant hormones, light, and other environmental signaling implicated in this process. Recent evidence indicates that changing levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) may also fine-tune the activity or synthesis of these proteins. This insight has been obtained by using mutants or treatments that alter the levels of ROS or RNS and demonstration of changing Auxin Transport and abundance of Transport proteins. The molecular mechanisms by which ROS and RNS lead to changes in Auxin Transport are not yet clear but likely include changes in protein synthesis and abundance. This chapter briefly introduces the key proteins and antioxidant molecules that control the levels of ROS and RNS and focuses on the evidence linking these changes to altered Auxin Transport.

  • Role for apyrases in polar Auxin Transport in Arabidopsis.
    Plant Physiology, 2012
    Co-Authors: Jian Wu, Gloria K Muday, Greg Clark, Stacey R. Lundy, David Arnold, Jing Chan, Wenqiang Tang, Gary Gardner

    Abstract:

    Recent evidence indicates that extracellular nucleotides regulate plant growth. Exogenous ATP has been shown to block Auxin Transport and gravitropic growth in primary roots of Arabidopsis (Arabidopsis thaliana). Cells limit the concentration of extracellular ATP in part through the activity of ectoapyrases (ectonucleoside triphosphate diphosphohydrolases), and two nearly identical Arabidopsis apyrases, APY1 and APY2, appear to share this function. These findings, plus the fact that suppression of APY1 and APY2 blocks growth in Arabidopsis, suggested that the expression of these apyrases could influence Auxin Transport. This report tests that hypothesis. The polar movement of [3H]indole-3-acetic acid in both hypocotyl sections and primary roots of Arabidopsis seedlings was measured. In both tissues, polar Auxin Transport was significantly reduced in apy2 null mutants when they were induced by estradiol to suppress the expression of APY1 by RNA interference. In the hypocotyl assays, the basal halves of APY-suppressed hypocotyls contained considerably lower free indole-3-acetic acid levels when compared with wild-type plants, and disrupted Auxin Transport in the APY-suppressed roots was reflected by their significant morphological abnormalities. When a green fluorescent protein fluorescence signal encoded by a DR5:green fluorescent protein construct was measured in primary roots whose apyrase expression was suppressed either genetically or chemically, the roots showed no signal asymmetry following gravistimulation, and both their growth and gravitropic curvature were inhibited. Chemicals that suppress apyrase activity also inhibit gravitropic curvature and, to a lesser extent, growth. Taken together, these results indicate that a critical step connecting apyrase suppression to growth suppression is the inhibition of polar Auxin Transport.

Enrico Scarpella – 3rd expert on this subject based on the ideXlab platform

  • Vein patterning by tissue-specific Auxin Transport
    Development, 2020
    Co-Authors: Priyanka Govindaraju, Carla Verna, Enrico Scarpella

    Abstract:

    Unlike in animals, in plants vein patterning does not rely on direct cell-cell interaction and cell migration; instead, it depends on the Transport of the plant hormone Auxin, which in turn depends on the activity of the PIN-FORMED1 (PIN1) Auxin Transporter. The current hypotheses of vein patterning by Auxin Transport propose that in the epidermis of the developing leaf PIN1-mediated Auxin Transport converges to peaks of Auxin level. From those convergence points of epidermal PIN1 polarity, Auxin would be Transported in the inner tissues where it would give rise to major veins. Here we tested predictions of this hypothesis and found them unsupported: epidermal PIN1 expression is neither required nor sufficient for AuxinTransport-dependent vein patterning, whereas inner-tissue PIN1 expression turns out to be both required and sufficient for AuxinTransport-dependent vein patterning. Our results refute all vein patterning hypotheses based on Auxin Transport from the epidermis and suggest alternatives for future tests.

  • Vein Patterning by Tissue-Specific Auxin Transport
    bioRxiv, 2019
    Co-Authors: Priyanka Govindaraju, Carla Verna, Enrico Scarpella

    Abstract:

    Unlike in animals, in plants vein patterning does not rely on direct cell-cell interaction and cell migration; instead, it depends on the Transport of the plant signal Auxin, which in turn depends on the activity of the PIN-FORMED1 (PIN1) Auxin Transporter. The current hypotheses of vein patterning by Auxin Transport propose that in the epidermis of the developing leaf PIN1-mediated Auxin Transport converges to peaks of Auxin level. From those convergence points of epidermal PIN1 polarity, Auxin would be Transported in the inner tissues where it would give rise to major veins. Here we tested predictions of this hypothesis and found them unsupported: epidermal PIN1 expression is neither required nor sufficient for AuxinTransport-dependent vein patterning, whereas inner-tissue PIN1 expression turns out to be both required and sufficient for AuxinTransport-dependent vein patterning. Our results refute all vein patterning hypotheses based on Auxin Transport from the epidermis and suggest alternatives for future tests.

  • coordination of tissue cell polarity by Auxin Transport and signaling
    eLife, 2019
    Co-Authors: Carla Verna, Megan G. Sawchuk, Sree Janani Ravichandran, Nguyen Manh Linh, Enrico Scarpella

    Abstract:

    Plants coordinate the polarity of hundreds of cells during vein formation, but how they do so is unclear. The prevailing hypothesis proposes that GNOM, a regulator of membrane trafficking, positions PIN-FORMED Auxin Transporters to the correct side of the plasma membrane; the resulting cell-to-cell, polar Transport of Auxin would coordinate tissue cell polarity and induce vein formation. Contrary to predictions of the hypothesis, we find that vein formation occurs in the absence of PIN-FORMED or any other intercellular AuxinTransporter; that the residual AuxinTransport-independent vein-patterning activity relies on Auxin signaling; and that a GNOM-dependent signal acts upstream of both Auxin Transport and signaling to coordinate tissue cell polarity and induce vein formation. Our results reveal synergism between Auxin Transport and signaling, and their unsuspected control by GNOM in the coordination of tissue cell polarity during vein patterning, one of the most informative expressions of tissue cell polarization in plants.