Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
Daisuke Maruyama
Nagoya Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, Japan; Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
Murat Shagirov
Department of Biological Sciences, National University of Singapore, Singapore, Singapore
Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
Yuki Hamamura
Division of Biological Sciences, Nagoya University Graduate School of Science, Nagoya, Japan
Ramesh Yelagandula
Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
Yusuke Toyama
Mechanobiology Institute, National University of Singapore, Singapore, Singapore; Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore, Singapore
Frédéric Berger
Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore, Singapore
In animals, microtubules and centrosomes direct the migration of gamete pronuclei for fertilization. By contrast, flowering plants have lost essential components of the centrosome, raising the question of how flowering plants control gamete nuclei migration during fertilization. Here, we use Arabidopsis thaliana to document a novel mechanism that regulates F-actin dynamics in the female gametes and is essential for fertilization. Live imaging shows that F-actin structures assist the male nucleus during its migration towards the female nucleus. We identify a female gamete-specific Rho-GTPase that regulates F-actin dynamics and further show that actin–myosin interactions are also involved in male gamete nucleus migration. Genetic analyses and imaging indicate that microtubules are dispensable for migration and fusion of male and female gamete nuclei. The innovation of a novel actin-based mechanism of fertilization during plant evolution might account for the complete loss of the centrosome in flowering plants.
