title: NENA, a Lotus japonicus homolog of Sec13, is required for rhizodermal infection by arbuscular mycorrhiza fungi and rhizobia but dispensable for cortical endosymbiotic development.
abstract: Legumes form symbioses with arbuscular mycorrhiza (AM) fungi and nitrogen fixing root nodule bacteria. Intracellular root infection by either endosymbiont is controlled by the activation of the calcium and calmodulin-dependent kinase (CCaMK), a central regulatory component of the plant's common symbiosis signaling network. We performed a microscopy screen for Lotus japonicus mutants defective in AM development and isolated a mutant, nena, that aborted fungal infection in the rhizodermis. NENA encodes a WD40 repeat protein related to the nucleoporins Sec13 and Seh1. Localization of NENA to the nuclear rim and yeast two-hybrid experiments indicated a role for NENA in a conserved subcomplex of the nuclear pore scaffold. Although nena mutants were able to form pink nodules in symbiosis with Mesorhizobium loti, root hair infection was not observed. Moreover, Nod factor induction of the symbiotic genes NIN, SbtM4, and SbtS, as well as perinuclear calcium spiking, were impaired. Detailed phenotypic analyses of nena mutants revealed a rhizobial infection mode that overcame the lack of rhizodermal responsiveness and carried the hallmarks of crack entry, including a requirement for ethylene. CCaMK-dependent processes were only abolished in the rhizodermis but not in the cortex of nena mutants. These data support the concept of tissue-specific components for the activation of CCaMK.
authors.affiliation: Biocenter University of Munich, Genetics, 82152 Martinsried, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Groth
authors.forename: Naoya
authors.initials: N
authors.lastname: Takeda
authors.forename: Jillian
authors.initials: J
authors.lastname: Perry
authors.forename: Hisaki
authors.initials: H
authors.lastname: Uchida
authors.forename: Stephan
authors.initials: S
authors.lastname: Dräxl
authors.forename: Andreas
authors.initials: A
authors.lastname: Brachmann
authors.forename: Shusei
authors.initials: S
authors.lastname: Sato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Trevor L
authors.initials: TL
authors.lastname: Wang
authors.forename: Martin
authors.initials: M
authors.lastname: Parniske
mesh_terms: D003001:Cloning, Molecular; D005816:Genetic Complementation Test; D000070116:Lotus / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D038821:Mycorrhizae / Q000472:pathogenicity*; D010940:Plant Proteins / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012231:Rhizobium / Q000472:pathogenicity*; D013559:Symbiosis; D020798:Two-Hybrid System Techniques
chemical_list: D010940:Plant Proteins