title: Expression of a class 1 hemoglobin gene and production of nitric oxide in response to symbiotic and pathogenic bacteria in Lotus japonicus.
abstract: Symbiotic nitrogen fixation by the collaboration between leguminous plants and rhizobia is an important system in the global nitrogen cycle, and some molecular aspects during the early stage of host-symbiont recognition have been revealed. To understand the responses of a host plant against various bacteria, we examined expression of hemoglobin (Hb) genes and production of nitric oxide (NO) in Lotus japonicus after inoculation with rhizobia or plant pathogens. When the symbiotic rhizobium Mesorhizobium loti was inoculated, expression of LjHb1 and NO production were induced transiently in the roots at 4 h after inoculation. In contrast, inoculation with the nonsymbiotic rhizobia Sinorhizobium meliloti and Bradyrhizobium japonicum induced neither expression of LjHb1 nor NO production. When L. japonicus was inoculated with plant pathogens (Ralstonia solanacearum or Pseudomonas syringae), continuous NO production was observed in roots but induction of LjHb1 did not occur. These results suggest that modulation of NO levels and expression of class 1 Hb are involved in the establishment of the symbiosis.
authors.affiliation: Graduate School of Science and Technology, Kagoshima University, Kagoshima, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Nagata
authors.forename: Ei-ichi
authors.initials: E
authors.lastname: Murakami
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Shimoda
authors.forename: Fuyuko
authors.initials: F
authors.lastname: Shimoda-Sasakura
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Kucho
authors.forename: Akihiro
authors.initials: A
authors.lastname: Suzuki
authors.forename: Mikiko
authors.initials: M
authors.lastname: Abe
authors.forename: Shiro
authors.initials: S
authors.lastname: Higashi
authors.forename: Toshiki
authors.initials: T
authors.lastname: Uchiumi
mesh_terms: D020561:Alphaproteobacteria / Q000502:physiology; D020369:Bradyrhizobium / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D006454:Hemoglobins / Q000235:genetics*; D054884:Host-Pathogen Interactions; D000070116:Lotus / Q000235:genetics* / Q000378:metabolism* / Q000382:microbiology; D008856:Microscopy, Fluorescence; D009569:Nitric Oxide / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016962:Sinorhizobium meliloti / Q000502:physiology*; D013559:Symbiosis / Q000235:genetics / Q000502:physiology
chemical_list: D006454:Hemoglobins; D009569:Nitric Oxide