title: Hemoglobin LjGlb1-1 is involved in nodulation and regulates the level of nitric oxide in the Lotus japonicus-Mesorhizobium loti symbiosis.
abstract: Leghemoglobins transport and deliver O2 to the symbiosomes inside legume nodules and are essential for nitrogen fixation. However, the roles of other hemoglobins (Hbs) in the rhizobia-legume symbiosis are unclear. Several Lotus japonicus mutants affecting LjGlb1-1, a non-symbiotic class 1 Hb, have been used to study the function of this protein in symbiosis. Two TILLING alleles with single amino acid substitutions (A102V and E127K) and a LORE1 null allele with a retrotransposon insertion in the 5'-untranslated region (96642) were selected for phenotyping nodulation. Plants of all three mutant lines showed a decrease in long infection threads and nodules, and an increase in incipient infection threads. About 4h after inoculation, the roots of mutant plants exhibited a greater transient accumulation of nitric oxide (NO) than did the wild-type roots; nevertheless, in vitro NO dioxygenase activities of the wild-type, A102V, and E127K proteins were similar, suggesting that the mutated proteins are not fully functional in vivo The expression of LjGlb1-1, but not of the other class 1 Hb of L. japonicus (LjGlb1-2), was affected during infection of wild-type roots, further supporting a specific role for LjGlb1-1. In conclusion, the LjGlb1-1 mutants reveal that this protein is required during rhizobial infection and regulates NO levels.
authors.affiliation: Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Fukudome
authors.affiliation: Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, Apartado 13034, 50080 Zaragoza, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Calvo-Begueria
authors.affiliation: Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kado
authors.affiliation: Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Osuki
authors.affiliation: Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, Apartado 13034, 50080 Zaragoza, Spain.
authors.forename: Maria Carmen
authors.initials: MC
authors.lastname: Rubio
authors.affiliation: Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan Centre for Carbohydrate Recognition and Signalling, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, 8000 Aarhus C, Denmark.
authors.forename: Ei-Ichi
authors.initials: E
authors.lastname: Murakami
authors.affiliation: Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Nagata
authors.affiliation: Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Kucho
authors.affiliation: Centre for Carbohydrate Recognition and Signalling, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, 8000 Aarhus C, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Sandal
authors.affiliation: Centre for Carbohydrate Recognition and Signalling, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, 8000 Aarhus C, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Stougaard
authors.affiliation: Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, Apartado 13034, 50080 Zaragoza, Spain becana@eead.csic.es uttan@sci.kagoshima-u.ac.jp.
authors.forename: Manuel
authors.initials: M
authors.lastname: Becana
authors.affiliation: Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan becana@eead.csic.es uttan@sci.kagoshima-u.ac.jp.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Uchiumi
mesh_terms: D006454:Hemoglobins / Q000378:metabolism / Q000502:physiology*; D000070116:Lotus / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology / Q000502:physiology*; D059128:Mesorhizobium / Q000378:metabolism / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism / Q000502:physiology*; D055170:Plant Root Nodulation / Q000502:physiology*; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction; D013559:Symbiosis / Q000502:physiology
chemical_list: D006454:Hemoglobins; D010940:Plant Proteins; D009569:Nitric Oxide
keywords: Hemoglobin; Lotus japonicus; Mesorhizobium loti; nitric oxide; nitrogen fixation; nodulation mutants; symbiosis.