title: Dynamic F-actin movement is essential for fertilization in Arabidopsis thaliana.
abstract: 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.
authors.affiliation: Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.
authors.forename: Tomokazu
authors.identifier: http://orcid.org/0000-0003-3803-3070
authors.initials: T
authors.lastname: Kawashima
authors.affiliation: Nagoya Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Maruyama
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
authors.forename: Murat
authors.initials: M
authors.lastname: Shagirov
authors.affiliation: Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.
authors.forename: Jing
authors.identifier: http://orcid.org/0000-0002-0989-7622
authors.initials: J
authors.lastname: Li
authors.affiliation: Division of Biological Sciences, Nagoya University Graduate School of Science, Nagoya, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hamamura
authors.affiliation: Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Yelagandula
authors.affiliation: Mechanobiology Institute, National University of Singapore, Singapore, Singapore.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Toyama
authors.affiliation: Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Berger
mesh_terms: D000199:Actins / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D005306:Fertilization; D008870:Microtubules / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D056771:Ovule / Q000378:metabolism; D011058:Pollen / Q000378:metabolism; D021381:Protein Transport; D059008:Time-Lapse Imaging; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000199:Actins; D029681:Arabidopsis Proteins; D009218:Myosins; D020741:rho GTP-Binding Proteins
keywords: F-actin; Rho-GTPase; arabidopsis; cytoskeleton; fertilization; gamete nuclear migration; plant biology; reproduction