title: IPD3 controls the formation of nitrogen-fixing symbiosomes in pea and Medicago Spp.
abstract: A successful nitrogen-fixing symbiosis requires the accommodation of rhizobial bacteria as new organelle-like structures, called symbiosomes, inside the cells of their legume hosts. Two legume mutants that are most strongly impaired in their ability to form symbiosomes are sym1/TE7 in Medicago truncatula and sym33 in Pisum sativum. We have cloned both MtSYM1 and PsSYM33 and show that both encode the recently identified interacting protein of DMI3 (IPD3), an ortholog of Lotus japonicus (Lotus) CYCLOPS. IPD3 and CYCLOPS were shown to interact with DMI3/CCaMK, which encodes a calcium- and calmodulin-dependent kinase that is an essential component of the common symbiotic signaling pathway for both rhizobial and mycorrhizal symbioses. Our data reveal a novel, key role for IPD3 in symbiosome formation and development. We show that MtIPD3 participates in but is not essential for infection thread formation and that MtIPD3 also affects DMI3-induced spontaneous nodule formation upstream of cytokinin signaling. Further, MtIPD3 appears to be required for the expression of a nodule-specific remorin, which controls proper infection thread growth and is essential for symbiosome formation.
authors.affiliation: Department of Molecular Biology, Wageningen University, Wageningen, the Netherlands.
authors.forename: Evgenia
authors.initials: E
authors.lastname: Ovchinnikova
authors.forename: Etienne-Pascal
authors.initials: EP
authors.lastname: Journet
authors.forename: Mireille
authors.initials: M
authors.lastname: Chabaud
authors.forename: Viviane
authors.initials: V
authors.lastname: Cosson
authors.forename: Pascal
authors.initials: P
authors.lastname: Ratet
authors.forename: Gerard
authors.initials: G
authors.lastname: Duc
authors.forename: Elena
authors.initials: E
authors.lastname: Fedorova
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Rik Op
authors.initials: RO
authors.lastname: den Camp
authors.forename: Vladimir
authors.initials: V
authors.lastname: Zhukov
authors.forename: Igor
authors.initials: I
authors.lastname: Tikhonovich
authors.forename: Alexey
authors.initials: A
authors.lastname: Borisov
authors.forename: Ton
authors.initials: T
authors.lastname: Bisseling
authors.forename: Erik
authors.initials: E
authors.lastname: Limpens
mesh_terms: D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers; D017343:Genes, Plant; D029902:Medicago / Q000235:genetics / Q000382:microbiology* / Q000502:physiology; D018613:Microscopy, Confocal; D038821:Mycorrhizae / Q000502:physiology; D009586:Nitrogen Fixation; D018532:Pisum sativum / Q000235:genetics / Q000382:microbiology* / Q000502:physiology; D030821:Plants, Genetically Modified; D016133:Polymerase Chain Reaction; D013559:Symbiosis
chemical_list: D017931:DNA Primers