title: Interaction between the moss Physcomitrella patens and Phytophthora: a novel pathosystem for live-cell imaging of subcellular defence.
abstract: Live-cell imaging of plant-pathogen interactions is often hampered by the tissue complexity and multicell layered nature of the host. Here, we established a novel pathosystem with the moss Physcomitrella patens as host for Phytophthora. The tip-growing protonema cells of this moss are ideal for visualizing interactions with the pathogen over time using high-resolution microscopy. We tested four Phytophthora species for their ability to infect P. patens and showed that P. sojae and P. palmivora were only rarely capable to infect P. patens. In contrast, P. infestans and P. capsici frequently and successfully penetrated moss protonemal cells, showed intracellular hyphal growth and formed sporangia. Next to these successful invasions, many penetration attempts failed. Here the pathogen was blocked by a barrier of cell wall material deposited in papilla-like structures, a defence response that is common in higher plants. Another common response is the upregulation of defence-related genes upon infection and also in moss we observed this upregulation in tissues infected with Phytophthora. For more advanced analyses of the novel pathosystem we developed a special set-up that allowed live-cell imaging of subcellular defence processes by high-resolution microscopy. With this set-up, we revealed that Phytophthora infection of moss induces repositioning of the nucleus, accumulation of cytoplasm and rearrangement of the actin cytoskeleton, but not of microtubules.
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands.|Laboratory of Cell Biology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Elysa J R
authors.initials: EJ
authors.lastname: Overdijk
authors.affiliation: Laboratory of Cell Biology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: DE Keijzer
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Deborah
authors.initials: D
authors.lastname: DE Groot
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Charikleia
authors.initials: C
authors.lastname: Schoina
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands.|Plant-Microbe Interactions, Utrecht University, Utrecht, The Netherlands.
authors.forename: Klaas
authors.initials: K
authors.lastname: Bouwmeester
authors.affiliation: Laboratory of Cell Biology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Tijs
authors.initials: T
authors.lastname: Ketelaar
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Francine
authors.initials: F
authors.lastname: Govers
mesh_terms: D000199:Actins / Q000378:metabolism; D019068:Bryopsida / Q000166:cytology* / Q000469:parasitology*; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival; D002473:Cell Wall / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D042541:Intracellular Space; D008853:Microscopy / Q000379:methods*; D010838:Phytophthora / Q000472:pathogenicity* / Q000502:physiology; D010935:Plant Diseases / Q000469:parasitology*
chemical_list: D000199:Actins
keywords: Live-cell imaging; Physcomitrella patens; Phytophthora capsici; Phytophthora infestans; plant-pathogen interaction; subcellular defence