Symbiotic rhizobium and nitric oxide induce gene expression of non-symbiotic hemoglobin in Lotus japonicus

Yoshikazu Shimoda, Maki Nagata, Akihiro Suzuki, Mikiko Abe, Shusei Sato, Tomohiko Kato, Satoshi Tabata, Shiro Higashi, Toshiki Uchiumi

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103 Citations (Scopus)


We characterized the expression profiles of LjHb1 and LjHb2, non-symbiotic hemoglobin (non-sym-Hb) genes of Lotus japonicus. Although LjHb1 and LjHb2 showed 77% homology in their cDNA sequences, LjHb2 is located in a unique position in the phylogenetic tree of plant Hbs. The 5′-upstream regions of both genes contain the motif AAAGGG at a position similar to that in promoters of other non-sym-Hb genes. Expression profiles obtained by using quantitative RT-PCR showed that LjHb1 and LjHb2 were expressed in all tissues of mature plants, and expression was enhanced in mature root nodules. LjHb1 was strongly induced under both hypoxic and cold conditions, and by the application of nitric oxide (NO) donor, whereas LjHb2 was induced only by the application of sucrose. LjHb1 was also induced transiently by the inoculation with the symbiotic rhizobium Mesorhizobium loti MAFF303099. Observations using fluorescence microscopy revealed the induction of LjHb1 expression corresponded to the generation of NO. These results suggest that non-sym-Hb and NO have important roles in stress adaptation and in the early stage of legume-rhizobium symbiosis. JSPP

Original languageEnglish
Pages (from-to)99-107
Number of pages9
JournalPlant and Cell Physiology
Issue number1
Publication statusPublished - 2005 Jan


  • Hypoxia
  • Lotus japonicus
  • Nitric oxide
  • Non-symbiotic hemoglobin
  • Plant hormone
  • Rhizobium


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