Polar auxin transport and patterning: grow with the flow.

Particularly in the fall, plant leaves demand attention as examples of the beauty of nature. Around that time, anyone can pick them up and have a close look at the variety in venation patterns. For a considerable time, biologists and mathematicians went one step farther, trying to find regularities in these patterns and rules behind them. Vein organization can be classified in several general patterns characteristic of a particular plant (Fig. 1A–D), suggesting that genetic input into the patterning system can be responsible for predictable gross changes in venation networks. However, close inspection reveals that there is considerable variation in the venation pattern in individual leaves of many plants. This reveals a large stochastic element in the mechanism by which veins are formed. In this issue of Genes & Development, Scarpella et al. (2006) provide new insights into how genetic and stochastic vein patterning processes might be related, but also connect the initiation of venation patterns to recent models of other auxin-dependent patterning processes in shoots and roots.

[1]  A. Nakano,et al.  The Arabidopsis GNOM ARF-GEF Mediates Endosomal Recycling, Auxin Transport, and Auxin-Dependent Plant Growth , 2003, Cell.

[2]  Ben Scheres,et al.  Polar PIN Localization Directs Auxin Flow in Plants , 2006, Science.

[3]  A Plausible Model of Phyllotaxis - Supporting Text , 2007 .

[4]  Hans Meinhardt,et al.  Models of pattern formation applied to plant development , 2004 .

[5]  Pierre Barbier de Reuille,et al.  Computer simulations reveal novel properties of the cell-cell signaling network at the shoot apex in /Arabidopsis , 2005 .

[6]  J. Friml,et al.  Control of leaf vascular patterning by polar auxin transport. , 2006, Genes & development.

[7]  E. Meyerowitz,et al.  Patterns of Auxin Transport and Gene Expression during Primordium Development Revealed by Live Imaging of the Arabidopsis Inflorescence Meristem , 2005, Current Biology.

[8]  Klaus Palme,et al.  AtPIN4 Mediates Sink-Driven Auxin Gradients and Root Patterning in Arabidopsis , 2002, Cell.

[9]  T. Nelson,et al.  Genetic Regulation of Vascular Tissue Patterning in Arabidopsis , 1999, Plant Cell.

[10]  A. Turing,et al.  The chemical basis of morphogenesis. 1953. , 1990, Bulletin of mathematical biology.

[11]  K. Koizumi,et al.  A series of novel mutants of Arabidopsis thaliana that are defective in the formation of continuous vascular network: calling the auxin signal flow canalization hypothesis into question. , 2000, Development.

[12]  G. Mitchison.  A model for vein formation in higher plants , 1980, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[13]  G. Jürgens,et al.  Local, Efflux-Dependent Auxin Gradients as a Common Module for Plant Organ Formation , 2003, Cell.

[14]  B. Scheres,et al.  Dissection of Arabidopsis ADP-RIBOSYLATION FACTOR 1 Function in Epidermal Cell Polarityw⃞ , 2005, The Plant Cell Online.

[15]  C. Kuhlemeier,et al.  Auxin Regulates the Initiation and Radial Position of Plant Lateral Organs , 2000, Plant Cell.

[16]  L. Sieburth,et al.  The SCARFACE gene is required for cotyledon and leaf vein patterning. , 2000, Development.

[17]  Tom Beeckman,et al.  Functional redundancy of PIN proteins is accompanied by auxin-dependent cross-regulation of PIN expression , 2005, Development.

[18]  A. Turing.  The chemical basis of morphogenesis , 1952, Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences.

[19]  A. Nakano,et al.  VAN3 ARF–GAP-mediated vesicle transport is involved in leaf vascular network formation , 2005, Development.

[20]  Michael Sauer,et al.  A Molecular Framework for Plant Regeneration , 2006, Science.

[21]  Hans Meinhardt,et al.  Models and Hypotheses , 1976 .

[22]  T. Sachs.  The Control of the Patterned Differentiation of Vascular Tissues , 1981 .

[23]  T. Berleth,et al.  Responses of plant vascular systems to auxin transport inhibition. , 1999, Development.

[24]  E. Scarpella,et al.  Stage-specific markers define early steps of procambium development in Arabidopsis leaves and correlate termination of vein formation with mesophyll differentiation , 2004, Development.

[25]  R. Amasino,et al.  The PLETHORA Genes Mediate Patterning of the Arabidopsis Root Stem Cell Niche , 2004, Cell.

[26]  L. Sieburth,et al.  Auxin is required for leaf vein pattern in Arabidopsis. , 1999, Plant physiology.

[27]  B. Scheres,et al.  Root development: new meanings for root canals? , 1998, Current opinion in plant biology.

[28]  M. Bennett,et al.  Regulation of phyllotaxis by polar auxin transport , 2003, Nature.

[29]  Ottoline Leyser,et al.  An Auxin-Dependent Distal Organizer of Pattern and Polarity in the Arabidopsis Root , 1999, Cell.

[30]  T. Sachs,et al.  Cell polarity and tissue patterning in plants , 1991 .

[31]  E. Mjolsness,et al.  An auxin-driven polarized transport model for phyllotaxis , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[32]  Michael Sauer,et al.  Efflux-dependent auxin gradients establish the apical–basal axis of Arabidopsis , 2003, Nature.

[33]  Klaus Palme,et al.  A PINOID-Dependent Binary Switch in Apical-Basal PIN Polar Targeting Directs Auxin Efflux , 2004, Science.

[34]  P. Prusinkiewicz,et al.  Reviewing models of auxin canalization in the context of leaf vein pattern formation in Arabidopsis. , 2005, The Plant journal : for cell and molecular biology.

[35]  T. Berleth.  Plant development: Hidden networks , 2000, Current Biology.

[36]  A. Müller,et al.  Regulation of polar auxin transport by AtPIN1 in Arabidopsis vascular tissue. , 1998, Science.

[37]  Klaus Palme,et al.  The PIN auxin efflux facilitator network controls growth and patterning in Arabidopsis roots , 2005, Nature.

[38]  Markus Langhans,et al.  Gradual shifts in sites of free-auxin production during leaf-primordium development and their role in vascular differentiation and leaf morphogenesis in Arabidopsis , 2003, Planta.