Plant Biol (Stuttg) 2006; 8(3): 360-370
DOI: 10.1055/s-2006-923969
Review Article

Georg Thieme Verlag Stuttgart KG · New York

Noise Yields Order - Auxin, Actin, and Polar Patterning

P. Nick1
  • 1Institut of Botany 1, University of Karlsruhe, Kaiserstraße 2, 76128 Karlsruhe, Germany
Further Information

Publication History

Received: December 16, 2005

Accepted: January 26, 2006

Publication Date:
15 May 2006 (online)

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Abstract

Plant patterns have to integrate environmental cues and to cope with a high level of noise in the sensory outputs of individual cells. In the first part of this review, we demonstrate that local self-amplification linked to lateral inhibition can meet this requirement. In the second part, we describe the search for candidates for such self-amplification loops in the context of auxin-dependent cell growth using Graminean coleoptiles as a model. Auxin-dependent reorganization of actin microfilaments interfered with the auxin sensitivity of growth. Auxin might control the intracellular transport of factors important for auxin sensing via the actomyosin system. By means of a rice mutant with elevated auxin responsiveness, we identified an auxin response factor (OsARF1), whose expression is upregulated by auxin as a second candidate for a self-amplification loop. We studied the cross-talk between auxin signalling and environmental cues in the rice mutant hebiba, where the photoinhibition of growth is impaired. We found that jasmonate plays a central role in this cross-talk correlated to a downregulation of auxin responsiveness. To obtain an insight into auxin-dependent coordination, we analyzed a tobacco cell line with axial cell divisions. By a combination of modelling and physiological manipulation, we could demonstrate that auxin synchronizes the divisions of adjacent cells on the background of strong heterogeneity of individual cells. We conclude that self-amplification of auxin signalling coupled to mutual competition for available auxin provides a versatile tool to fulfill the special requirements posed by patterning in plants.

References

P. Nick

Institut of Botany 1
University of Karlsruhe

Kaiserstraße 2

76128 Karlsruhe

Germany

Email: peter.nick@bio.uni-karlsruhe.de

Guest Editor: R. Reski