LjMOT1, a high-affinity molybdate transporter from Lotus japonicus, is essential for molybdate uptake, but not for the delivery to nodules

Guilan Duan, Tsuneo Hakoyama, Takehiro Kamiya, Hiroki Miwa, Fabien Lombardo, Shusei Sato, Satoshi Tabata, Zheng Chen, Toshihiro Watanabe, Takuro Shinano, Toru Fujiwara

    Research output: Contribution to journalArticlepeer-review

    9 Citations (Scopus)

    Abstract

    Molybdenum (Mo) is an essential nutrient for plants, and is required for nitrogenase activity of legumes. However, the pathways of Mo uptake from soils and then delivery to the nodules have not been characterized in legumes. In this study, we characterized a high-affinity Mo transporter (LjMOT1) from Lotus japonicus. Mo concentrations in an ethyl methanesulfonate–mutagenized line (ljmot1) decreased by 70–95% compared with wild-type (WT). By comparing the DNA sequences of four AtMOT1 homologs between mutant and WT lines, one point mutation was found in LjMOT1, which altered Trp292 to a stop codon; no mutation was found in the other homologous genes. The phenotype of Mo concentrations in F2 progeny from ljmot1 and WT crosses were associated with genotypes of LjMOT1. Introduction of endogenous LjMOT1 to ljmot1 restored Mo accumulation to approximately 60–70% of the WT. Yeast expressing LjMOT1 exhibited high Mo uptake activity, and the Km was 182 nm. LjMOT1 was expressed mainly in roots, and its expression was not affected by Mo supply or rhizobium inoculation. Although Mo accumulation in the nodules of ljmot1 was significantly lower than that of WT, it was still high enough for normal nodulation and nitrogenase activity, even for cotyledons-removed ljmot1 plants grown under low Mo conditions, in this case the plant growth was significantly inhibited by Mo deficiency. Our results suggest that LjMOT1 is an essential Mo transporter in L. japonicus for Mo uptake from the soil and growth, but is not for Mo delivery to the nodules.

    Original languageEnglish
    Pages (from-to)1108-1119
    Number of pages12
    JournalPlant Journal
    Volume90
    Issue number6
    DOIs
    Publication statusPublished - 2017 Jun

    Keywords

    • Lotus japonicus
    • molybdate transporter
    • molybdenum
    • nitrogen fixation
    • nodule

    ASJC Scopus subject areas

    • Genetics
    • Plant Science
    • Cell Biology

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