title: Trafficking to the outer polar domain defines the root-soil interface.
abstract: In animals, the interface between organism and environment is constituted by the epithelium. In plants, the exchange of nutrients and signals between root and soil is crucial for their survival, but the cellular mechanisms underlying the epithelium-like function and specific localization of proteins to the root surface have not been identified. Here we analyze the mechanism of polar delivery to the root-soil interface of the proteins BOR4, ABCG37, and PEN3, which transport nutrients, transport plant hormones, and are required for pathogen defense, respectively. The simultaneous visualization of these proteins and the apical and basal cargos in a single cell demonstrates that the outermost cell side represents an additional polar domain. Delivery to this outer polar domain depends on ARF GEF and actin function but does not require known molecular components of the apical or basal targeting. The outer polar delivery is, in contrast to known basal and apical cargos, mediated by the polar secretion. Our findings show that the outermost cell membranes of roots define an additional polar domain in plant cells along with a specific, previously uncharacterized, polar targeting mechanism that is important for defining the functional, epithelium-like root-soil interface.
authors.affiliation: Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052 Gent, Belgium.
authors.forename: Lukasz
authors.initials: L
authors.lastname: Langowski
authors.forename: Kamil
authors.initials: K
authors.lastname: Růzicka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Naramoto
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kleine-Vehn
authors.forename: Jirí
authors.initials: J
authors.lastname: Friml
mesh_terms: D000070996:ATP Binding Cassette Transporter, Subfamily G; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017920:Antiporters / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000033:anatomy & histology / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D012987:Soil
chemical_list: D000070996:ATP Binding Cassette Transporter, Subfamily G; D018528:ATP-Binding Cassette Transporters; D017920:Antiporters; D029681:Arabidopsis Proteins; C524889:BOR4 protein, Arabidopsis; C510424:PDR8 protein, Arabidopsis; C515019:PDR9 protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D012987:Soil