Universitaet Bern Institute of Plant Sciences swissuniversity.ch  

Systems biology of phyllotaxis; a unique problem in development

Two M.Sc. studentships

In the majority of higher plants, leaves are arranged around the stem in spirals, with the divergence angle between successive leaves close to 137.5° (1). This is the golden angle, related to the Fibonacci series (1, 1, 2, 3, 8, 13, 21,…). Over the years, work in Bern has unraveled the molecular mechanism of phyllotaxis. We have shown that phyllotaxis is controlled by a novel mechanism that involves active transport of the plant hormone auxin (1-4). In 2008 the Swiss government funded an ambitious systems biology project to study the molecular, mathematical and mechanical aspects of phyllotaxis (5).

The M.Sc. students’ projects aim to characterize upstream and downstream components of the regulatory mechanism, in particular auxin transporters and proteins that modify the mechanical properties of the cell walls. The data will be used to construct computer simulations. The projects involve collaborations with physicists and mathematicians in Canada, France and Israel.

Classical and molecular genetics
Confocal and scanning microscopy
Micromanipulation of meristems
Analysis of tissue mechanics
Computer modeling


  1. Kuhlemeier, C. Phyllotaxis. Trends in Plant Science 12: 143-1150 (2007)
  2. Reinhardt, D., Pesce, E.-R., Stieger, P., Mandel, T., Baltensperger, K., Bennett, M., Traas, J., Friml, J. and Kuhlemeier, C. Regulation of phyllotaxis by polar auxin transport. Nature 426: 255-260 (2003)
  3. Smith, R., Guyomarc’h, S., Mandel, T., Reinhardt, D., Kuhlemeier, C. and Prusinkiewicz, P. A plausible model of phyllotaxis. Proc. Natl. Acad. Sci. USA 103: 1301-1306 (2006)
  4. Bayer, E.M., Smith, R.S., Mandel, T., Nakayama, N., Sauer, M., Prusinkiewicz, P. and Kuhlemeier, C. Integration of transport-based models for phyllotaxis and midvein formation. Genes Devel. 23: 373-384 (2009).
  5. SystemsX: Plant Growth in a Changing Environment


 Prof. Cris Kuhlemeier

 Institute of Plant Sciences

 Prof. Richard Smith

 Institute of Plant Sciences
 031-631 5223

Arabidopsis shoot meristem with spiral organ arrangement