Root Apical Meristem Pattern Hormone Circuitry and Transcriptional Networks

M.B. Bitonti and A. Chiappetta

Contents

1 Introduction 38

2 An Overview of RAM Organization in Plants 38

3 Environmental Cues and RAM Patterning 41

4 Arabidopsis thaliana 43

4.1 Morphogenetic Establishment of the RAM During Embryogenesis 43

4.2 RAM Pattern 44

4.3 Positional Signaling and Genetic Network Operating in Root Patterning 45

5 Hormonal Circuitry in Determining RAM Size and Pattern 55

5.1 Auxin/Cytokinin Interplay 55

5.2 Ethylene, Gibberellin, Abscisic Acid, and Brassinosteroids 58

6 Stem-Cell State and Chromatin Remodelers 60

7 Conclusions and Perspectives 62

References 63

Abstract In higher plants, growth and development relies on the spatiotemporal regulation of gene expression, which is under the control of both endogenous signals and external stimuli. In this chapter, recent advances in defining signaling machinery and genetic frameworks that underlie RAM patterning and maintenance are reviewed, with a focus on the interplay between different hormone classes. The evidence for an epigenetic control of the root developmental program is also briefly considered. Conceivably, many other aspects are still to be elucidated. Future challenges deal with, on the one hand, understanding how signaling and genetic programs are modulated to achieve adaptative traits under environmental pressure and, on the other, how cell fate is reprogrammed in vivo and in vitro. We conclude that knowledge from the plant model, Arabidopsis thaliana, could enhance our understanding of more complex species encountered in crop

Department of Ecology, University of Calabria, Arcavacata Rende (CS), Italy e-mail: [email protected]; [email protected]

DOI 10.1007/978-3-642-13145-5_2, © Springer-Verlag Berlin Heidelberg 2011

Sl systems and could provide relevant perspectives for both crop improvement and plant biotechnology.

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