title: Into the Root: How Cytokinin Controls Rhizobial Infection.
abstract: Leguminous plants selectively initiate primary responses to rhizobial nodulation factors (NF) that ultimately lead to symbiotic root nodule formation. Functioning downstream, cytokinin has emerged as the key endogenous plant signal for nodule differentiation, but its role in mediating rhizobial entry into the root remains obscure. Nonetheless, such a role is suggested by aberrant infection phenotypes of plant mutants with defects in cytokinin signaling. We postulate that cytokinin participates in orchestrating signaling events that promote rhizobial colonization of the root cortex and limit the extent of subsequent infection at the root epidermis, thus maintaining homeostasis of the symbiotic interaction. We further argue that cytokinin signaling must have been crucial during the evolution of plant cell predisposition for rhizobial colonization.
authors.affiliation: Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, London, ONT, NV5 4T3, Canada; Department of Biology, University of Western Ontario, London, ONT, N6A 5BF, Canada.
authors.forename: Mandana
authors.initials: M
authors.lastname: Miri
authors.affiliation: Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, London, ONT, NV5 4T3, Canada.
authors.forename: Preetam
authors.initials: P
authors.lastname: Janakirama
authors.affiliation: Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, London, ONT, NV5 4T3, Canada; Current address: Intrexon Corporation, 329 Oyster Pt. Blvd., South San Francisco, CA 94080, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Held
authors.affiliation: Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, London, ONT, NV5 4T3, Canada.
authors.forename: Loretta
authors.initials: L
authors.lastname: Ross
authors.affiliation: Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, London, ONT, NV5 4T3, Canada; Department of Biology, University of Western Ontario, London, ONT, N6A 5BF, Canada. Electronic address: Krzysztof.Szczyglowski@agr.gc.ca.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Szczyglowski
mesh_terms: D003583:Cytokinins / Q000378:metabolism*; D005030:Ethylenes / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism* / Q000382:microbiology*; D012231:Rhizobium / Q000502:physiology*; D015398:Signal Transduction; D013559:Symbiosis
chemical_list: D003583:Cytokinins; D005030:Ethylenes; C036216:ethylene
keywords: Legumes; cytokinin; ethylene; infection; symbiosis