title: Medicago truncatula IPD3 is a member of the common symbiotic signaling pathway required for rhizobial and mycorrhizal symbioses.
abstract: Legumes form endosymbiotic associations with nitrogen-fixing bacteria and arbuscular mycorrhizal (AM) fungi which facilitate nutrient uptake. Both symbiotic interactions require a molecular signal exchange between the plant and the symbiont, and this involves a conserved symbiosis (Sym) signaling pathway. In order to identify plant genes required for intracellular accommodation of nitrogen-fixing bacteria and AM fungi, we characterized Medicago truncatula symbiotic mutants defective for rhizobial infection of nodule cells and colonization of root cells by AM hyphae. Here, we describe mutants impaired in the interacting protein of DMI3 (IPD3) gene, which has been identified earlier as an interacting partner of the calcium/calmodulin-dependent protein, a member of the Sym pathway. The ipd3 mutants are impaired in both rhizobial and mycorrhizal colonization and we show that IPD3 is necessary for appropriate Nod-factor-induced gene expression. This indicates that IPD3 is a member of the common Sym pathway. We observed differences in the severity of ipd3 mutants that appear to be the result of the genetic background. This supports the hypothesis that IPD3 function is partially redundant and, thus, additional genetic components must exist that have analogous functions to IPD3. This explains why mutations in an essential component of the Sym pathway have defects at late stages of the symbiotic interactions.
authors.affiliation: Agricultural Biotechnology Center, Hungary.
authors.forename: Beatrix
authors.initials: B
authors.lastname: Horváth
authors.forename: Li Huey
authors.initials: LH
authors.lastname: Yeun
authors.forename: Agota
authors.initials: A
authors.lastname: Domonkos
authors.forename: Gábor
authors.initials: G
authors.lastname: Halász
authors.forename: Enrico
authors.initials: E
authors.lastname: Gobbato
authors.forename: Ferhan
authors.initials: F
authors.lastname: Ayaydin
authors.forename: Krisztina
authors.initials: K
authors.lastname: Miró
authors.forename: Sibylle
authors.initials: S
authors.lastname: Hirsch
authors.forename: Jongho
authors.initials: J
authors.lastname: Sun
authors.forename: Million
authors.initials: M
authors.lastname: Tadege
authors.forename: Pascal
authors.initials: P
authors.lastname: Ratet
authors.forename: Kirankumar S
authors.initials: KS
authors.lastname: Mysore
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Ané
authors.forename: Giles E D
authors.initials: GE
authors.lastname: Oldroyd
authors.forename: Péter
authors.initials: P
authors.lastname: Kaló
mesh_terms: D000483:Alleles; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D017343:Genes, Plant; D005816:Genetic Complementation Test; D046913:Medicago truncatula / Q000235:genetics* / Q000382:microbiology / Q000502:physiology; D038821:Mycorrhizae / Q000502:physiology*; D009586:Nitrogen Fixation; D060888:Real-Time Polymerase Chain Reaction; D012231:Rhizobium / Q000502:physiology*; D015398:Signal Transduction; D013559:Symbiosis; D020798:Two-Hybrid System Techniques