Planta

, Volume 212, Issue 5, pp 864–871

In vivo evidence that Ids3 from Hordeum vulgare encodes a dioxygenase that converts 2′-deoxymugineic acid to mugineic acid in transgenic rice

Authors

  • Takanori Kobayashi
    • Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
  • Hiromi Nakanishi
    • Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
  • Michiko Takahashi
    • Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, 2-1-6 Sengen, Tsukuba 305-0047, Japan
  • Shinji Kawasaki
    • National Institute of Agrobiological Resources, 2-1-2 Kan'non-dai, Tsukuba 305-8602, Japan
  • Naoko-Kishi Nishizawa
    • Laboratory of Plant Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
  • Satoshi Mori
    • Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan

DOI: 10.1007/s004250000453

Cite this article as:
Kobayashi, T., Nakanishi, H., Takahashi, M. et al. Planta (2001) 212: 864. doi:10.1007/s004250000453

Abstract.

We proposed that an Fe-deficiency-induced gene, Ids3 (Iron deficiency specific clone no. 3), from barley (Hordeum vulgare L.) roots encodes a dioxygenase that catalyzes the hydroxylation step from 2′-deoxymugineic acid (DMA) to mugineic acid (MA). To prove this hypothesis, we introduced the Ids3 gene into rice (Oryza sativa L.), which lacks Ids3 homologues and secretes DMA, but not MA. Transgenic rice plants, carrying either Ids3 cDNA or a barley genomic DNA fragment (20 kb) containing Ids3, were obtained using Agrobacterium-mediated transformation. Ids3 cDNA under the control of the cauliflower mosaic virus 35S promoter was constitutively expressed in both the roots and the leaves of the transgenic rice, regardless of Fe nutrition status. In contrast, in the roots of transformants carrying a barley genomic fragment, transcripts of Ids3 were markedly increased in response to Fe deficiency. Slight expression of Ids3 was also observed in the leaves of the Fe-deficient plants. Western blot analysis confirmed the induction of Ids3 in response to Fe deficiency in the roots of the transformants carrying a genomic fragment. These expression patterns indicate that the 5′-flanking region of Ids3 works as a strong Fe-deficiency-inducible promoter in rice, as well as in barley. Both kinds of transgenic rice secreted MA in addition to DMA under Fe-deficient conditions, but wild-type rice secreted only DMA. This is in vivo evidence that IDS3 is the “MA synthase” that converts DMA to MA.

Key words: DioxygenaseIron deficiencyMugineic acid family phytosiderophoresMugineic acid synthaseOryza (transgenic)Transgenic rice

Copyright information

© Springer-Verlag Berlin Heidelberg 2001