title: The Thiamine Biosynthesis Gene THI1 Promotes Nodule Growth and Seed Maturation.
abstract: Thiamine (vitamin B1) is essential for living organisms. Unlike animals, plants can synthesize thiamine. In Lotus japonicus, the expression of two thiamine biosynthesis genes, THI1 and THIC, was enhanced by inoculation with rhizobia but not by inoculation with arbuscular mycorrhizal fungi. THIC and THI2 (a THI1 paralog) were expressed in uninoculated leaves. THI2-knockdown plants and the transposon insertion mutant thiC had chlorotic leaves. This typical phenotype of thiamine deficiency was rescued by an exogenous supply of thiamine. In wild-type plants, THI1 was expressed mainly in roots and nodules, and the thi1 mutant had green leaves even in the absence of exogenous thiamine. THI1 was highly expressed in actively dividing cells of nodule primordia. The thi1 mutant had small nodules, and this phenotype was rescued by exogenous thiamine and by THI1 complementation. Exogenous thiamine increased nodule diameter, but the level of arbuscular mycorrhizal colonization was unaffected in the thi1 mutant or by exogenous thiamine. Expression of symbiotic marker genes was induced normally, implying that mainly nodule growth was delayed in the thi1 mutant. Furthermore, this mutant formed many immature seeds with reduced seed weight. These results indicate that thiamine biosynthesis mediated by THI1 enhances nodule enlargement and is required for seed development in L. japonicus.
authors.affiliation: Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (M.N., M.K., N.T.).|Genetics, Faculty of Biology, University of Munich, 82152 Martinsried, Germany (M.P.); and.|Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (M.K., N.T.).
authors.forename: Miwa
authors.initials: M
authors.lastname: Nagae
authors.affiliation: Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (M.N., M.K., N.T.).|Genetics, Faculty of Biology, University of Munich, 82152 Martinsried, Germany (M.P.); and.|Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (M.K., N.T.).
authors.forename: Martin
authors.identifier: 0000-0001-8561-747X
authors.initials: M
authors.lastname: Parniske
authors.affiliation: Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (M.N., M.K., N.T.).|Genetics, Faculty of Biology, University of Munich, 82152 Martinsried, Germany (M.P.); and.|Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (M.K., N.T.).
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kawaguchi
authors.affiliation: Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (M.N., M.K., N.T.); takedan@nibb.ac.jp.|Genetics, Faculty of Biology, University of Munich, 82152 Martinsried, Germany (M.P.); and takedan@nibb.ac.jp.|Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (M.K., N.T.) takedan@nibb.ac.jp.
authors.forename: Naoya
authors.initials: N
authors.lastname: Takeda
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics*; D015169:Colony Count, Microbial; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D055785:Gene Knockdown Techniques; D017343:Genes, Plant; D000070116:Lotus / Q000235:genetics* / Q000382:microbiology; D009154:Mutation / Q000235:genetics; D038821:Mycorrhizae / Q000187:drug effects / Q000378:metabolism; D010641:Phenotype; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D018520:Plant Shoots / Q000033:anatomy & histology / Q000187:drug effects; D018087:Plastids / Q000378:metabolism; D012231:Rhizobium / Q000187:drug effects / Q000254:growth & development; D053204:Root Nodules, Plant / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D013347:Subcellular Fractions / Q000378:metabolism; D013559:Symbiosis; D013831:Thiamine / Q000096:biosynthesis* / Q000494:pharmacology
chemical_list: D010940:Plant Proteins; D013831:Thiamine