A model of differential growth-guided apical hook formation in plants

Petra Zadnikova1,2, Krzysztof Wabnik3, Anas Abuzeineh1,2, Marcal Gallemi3, Dominique Van Der Straeten4, Richard S. Smith5, Dirk Inze1,2, Jiri Friml3, Przemyslaw Prusinkiewicz4, and Eva Benkova3.

1 Department of Plant Systems Biology, Ghent University
2 Department of Plant Biotechnology and Bioinformatics, Ghent University
3 Institute of Science and Technology Austria
4 Laboratory of Functional Plant Biology, Ghent University
5 Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research
6 Department of Computer Science, University of Calgary

Abstract

Differential cell growth enables flexible organ bending in the presence of environmental signals such as light or gravity. A prominent example of the developmental processes based on differential cell growth is the formation of the apical hook that protects the fragile shoot apical meristem when it breaks through the soil during germination. Here, we combined in silico and in vivo approaches to identify a minimal mechanism producing auxin gradient-guided differential growth during the establishment of the apical hook in the model plant Arabidopsis thaliana. Computer simulation models based on experimental data demonstrate that asymmetric expression of the PIN-FORMED auxin efflux carrier at the concave (inner) versus convex (outer) side of the hook suffices to establish an auxin maximum in the epidermis at the concave side of the apical hook. Furthermore, we propose a mechanism that translates this maximum into differential growth, and thus curvature, of the apical hook. Through a combination of experimental and in silico computational approaches, we have identified the individual contributions of differential cell elongation and proliferation to defining the apical hook and reveal the role of auxin-ethylene crosstalk in balancing these two processes.

Reference

Petra Zadnikova, Krzysztof Wabnik, Anas Abuzeineh, Marcal Gallemi, Dominique Van Der Straeten, Richard S. Smith, Dirk Inze, Jiri Friml, Przemyslaw Prusinkiewicz, and Eva Benkova. A model of differential growth-guided apical hook formation in plants. The Plant Cell (2016): tpc-00569.

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