title: Filamentous actin accumulates during plant cell penetration and cell wall plug formation in Phytophthora infestans.
abstract: The oomycete Phytophthora infestans is the cause of late blight in potato and tomato. It is a devastating pathogen and there is an urgent need to design alternative strategies to control the disease. To find novel potential drug targets, we used Lifeact-eGFP expressing P. infestans for high resolution live cell imaging of the actin cytoskeleton in various developmental stages. Previously, we identified actin plaques as structures that are unique for oomycetes. Here we describe two additional novel actin configurations; one associated with plug deposition in germ tubes and the other with appressoria, infection structures formed prior to host cell penetration. Plugs are composed of cell wall material that is deposited in hyphae emerging from cysts to seal off the cytoplasm-depleted base after cytoplasm retraction towards the growing tip. Preceding plug formation there was a typical local actin accumulation and during plug deposition actin remained associated with the leading edge. In appressoria, formed either on an artificial surface or upon contact with plant cells, we observed a novel aster-like actin configuration that was localized at the contact point with the surface. Our findings strongly suggest a role for the actin cytoskeleton in plug formation and plant cell penetration.
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.|Laboratory of Cell Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
authors.forename: Kiki
authors.identifier: 0000-0001-9387-2243
authors.initials: K
authors.lastname: Kots
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.|Business Unit Biointeractions and Plant Health, Wageningen University and Research, Wageningen Plant Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
authors.forename: Harold J G
authors.identifier: 0000-0002-0883-219X
authors.initials: HJ
authors.lastname: Meijer
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.|Plant-Microbe Interactions, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
authors.forename: Klaas
authors.identifier: 0000-0002-8141-3880
authors.initials: K
authors.lastname: Bouwmeester
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
authors.forename: Francine
authors.identifier: 0000-0001-5311-929X
authors.initials: F
authors.lastname: Govers
authors.affiliation: Laboratory of Cell Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. tijs.ketelaar@wur.nl.
authors.forename: Tijs
authors.identifier: 0000-0001-9506-7264
authors.initials: T
authors.lastname: Ketelaar
mesh_terms: D000199:Actins / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism; D003470:Culture Media; D025301:Hyphae / Q000166:cytology / Q000378:metabolism; D018551:Solanum lycopersicum / Q000166:cytology / Q000382:microbiology; D055750:Phytophthora infestans / Q000166:cytology* / Q000378:metabolism*; D059828:Plant Cells / Q000378:metabolism*; D021381:Protein Transport
chemical_list: D000199:Actins; D003470:Culture Media; D002482:Cellulose
keywords: Actin cytoskeleton; Appressorium; Late blight; Lifeact; Oomycete; Plant pathogen