title: The relationship between thiamine and two symbioses: Root nodule symbiosis and arbuscular mycorrhiza.
abstract: Lotus japonicus THIC is expressed in all organs, and the encoded protein catalyzes thiamine biosynthesis. Loss of function produces chlorosis, a typical thiamine-deficiency phenotype, and mortality. To investigate thiamine's role in symbiosis, we focused on THI1, a thiamine-biosynthesis gene expressed in roots, nodules, and seeds. The thi1 mutant had green leaves, but formed small nodules and immature seeds. These phenotypes were rescued by THI1 complementation and by exogenous thiamine. Thus, THI1 is required for nodule enlargement and seed maturation. On the other hand, colonization by arbuscular mycorrhiza (AM) fungus Rhizophagus irregularis was not affected in the thi1 mutant or by exogenous thiamine. However, spores of R. irregularis stored more thiamine than the source (host plants), despite lacking thiamine biosynthesis genes. Therefore, disturbance of the thiamine supply would affect progeny phenotypes such as spore formation and hyphal growth. Further investigation will be required to elucidate thiamine's effect on AM.
authors.affiliation: a Division of Symbiotic Systems, National Institute for Basic Biology , Myodaiji, Okazaki , Aichi , Japan.
authors.forename: Miwa
authors.initials: M
authors.lastname: Nagae
authors.affiliation: b Genetics, Faculty of Biology, University of Munich (LMU) , Martinsried , Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Parniske
authors.affiliation: a Division of Symbiotic Systems, National Institute for Basic Biology , Myodaiji, Okazaki , Aichi , Japan.|c Department of Basic Biology , School of Life Science, Graduate University for Advanced Studies (SOKENDAI) , Myodaiji, Okazaki , Aichi , Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kawaguchi
authors.affiliation: a Division of Symbiotic Systems, National Institute for Basic Biology , Myodaiji, Okazaki , Aichi , Japan.|c Department of Basic Biology , School of Life Science, Graduate University for Advanced Studies (SOKENDAI) , Myodaiji, Okazaki , Aichi , Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Takeda
mesh_terms: D000070116:Lotus / Q000378:metabolism / Q000382:microbiology; D038821:Mycorrhizae / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism* / Q000382:microbiology*; D053204:Root Nodules, Plant / Q000378:metabolism / Q000382:microbiology; D013559:Symbiosis / Q000502:physiology*; D013831:Thiamine / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D013831:Thiamine
keywords: Arbuscular mycorrhiza; Lotus japonicus; root nodule symbiosis; thiamine