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The role of cytoskeleton in the auxin-regulated plant morphogenesis |
 Školitel |
RNDr. Jan Petrášek, Ph.D.
Katedra experimentální biologie rostlin PřF UK, ÚEB AV ČR, v.v.i. Praha
kontakt: petrasek@ueb.cas.cz
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General background, main objectives and methods:
 Plant hormone auxin is important for almost all aspects of plant development, ranging from the embryogenesis to the formation of fruits. It triggers a spectrum of downstream events that include both transcriptional and non-transcriptional regulatory pathways (for review see Vanneste and Friml, 2009). Besides auxin biosynthesis and metabolism, its cell-to-cell transport is crucial for the establishment of developmentally informative concentration gradients. There are numerous examples, where the coordinated interplay between several auxin influx and efflux carriers regulates the fate of individual cells triggering specific developmental programme (reviewed in Petrášek and Friml, 2009). The nature of auxin activity could be in principle understood as "morphogenic", where both actual auxin concentration and sensitivity of downstream signal transduction pathways are decisive for setting up specific developmental cues.
This Ph.D. project is generally focused on the role of cytoskeleton-mediated deposition of membrane vesicles containing auxin transporters. It will concentrate primarily on the in vivo analysis of the intracellular distribution and dynamics of fluorescent protein fusions of auxin influx carriers (AUX1/LAX family) and auxin efflux carriers (PIN and ABCB families) using laser scanning and spinning disc confocal microscopy. In particular, two processes that are known to be regulated both by auxin transport across plasma membrane and interplay between actin and microtubular cytoskeleton will be studied in Arabidopsis thaliana. Firstly, we will focus on the early formation of individual leaf epidermal cells during the development of leaf primordium and the morphogenesis of epidermal and sub/epidermal cells of mature leaf during the early phases of auxin canalization (for review see Scarpella et al., 2010). The role of regulated auxin transport and auxin transporters in leaf epidermis has been suggested only recently and is not fully understood (Li et al., 2011, Nagawa et al., 2012, Xu et al., 2010). Secondly, we will focus on the early phases of gravitropic bending of the root tip. In both these processes, detailed analysis of the distribution of auxin influx and efflux carriers will be performed using both in vivo approaches and immunostainings using specific antibodies. Arabidopsis thaliana plants carrying mutation in cytoskeleton or cytoskeleton-associated proteins (tubulins, actins, their associated partners and actin nucleating complexes) will be crossed with marker lines carrying fluorescent auxin transporters and auxin sensitive promoter elements (DR5::GFP, DR5::GUS, DII-VENUS). Comparative analysis of crossed lines with corresponding wild type situation will contribute greatly for the identification of new cytoskeletal determinants of auxin carrier deposition in the above mentioned auxin-driven processes.
Grant support:
This work will be supported by research grant of the supervisor, Czech Science Foundation project GAP305/11/2476, Auxin transport and cytoskeleton in the morphogenesis of plant cells (Jan Petrášek, 2011-2014).
References:
Li, H. J., Lin, D.S., Dhonukshe, P., Nagawa, S., Chen, D.D, Friml, J., Scheres, B., Guo, H.W., Yang, Z.B. Phosphorylation switch modulates the interdigitated pattern of PIN1 localization and cell expansion in Arabidopsis leaf epidermis. Cell Research, 21, 970-978, 2011.
Nagawa, S., Xu, T., Lin, D., Dhonukshe, P., Zhang, X., Friml, J., Scheres, B., Fu, Y., Yang, Z. ROP GTPase-Dependent Actin Microfilaments Promote PIN1 Polarization by Localized Inhibition of Clathrin-Dependent Endocytosis. PLoS Biol. 10(4):e1001299, 2012.
Petrášek, J., Friml, J. Auxin transport routes in plant development. Development, 136, 2675-2688, 2009.
Scarpella, E., Barkoulas, M., Tsiantis, M. Control of leaf and vein development by auxin. Cold Spring Harb Perspect Biol 2: a001511, 2010.
Vanneste, S., and Friml, J. Auxin: A Trigger for Change in Plant Development. Cell 136, 1005-1016, 2009.
Xu, T.D., Wen, M.Z., Nagawa, S., Fu, Y., Chen, J.G., Wu. M.J., Perrot-Rechenmann, C., Friml, J., Jones, A.M., Yang, Z.B. Cell Surface- and Rho GTPase-Based Auxin Signaling Controls Cellular Interdigitation in Arabidopsis. Cell 143: 99-110, 2010.
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