Structural requirements of strigolactones for shoot branching inhibition in rice and arabidopsis

Mikihisa Umehara, Mengmeng Cao, Kohki Akiyama, Tomoki Akatsu, Yoshiya Seto, Atsushi Hanada, Weiqiang Li, Noriko Takeda-Kamiya, Yu Morimoto, Shinjiro Yamaguchi

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    51 Citations (Scopus)

    Abstract

    The structural requirements of strigolactones (SLs) involved in germination induction of root parasitic plants and hyphal branching in arbuscular mycorrhizal (AM) fungi have been extensively studied. However, our knowledge of the requirements of SLs involved in shoot branching inhibition in plants is still limited. To address this question, we investigated the structure-activity relationships of SLs in shoot branching inhibition in rice and Arabidopsis. SLs possess a four-ring structure, with a tricyclic lactone (ABC-rings) connected to a methylbutenolide part (D-ring) via an enol ether bridge. Here, we show that the the (R) configuration at C-2', which determines the steric position of the D-ring relative to the enol ether olefin bond, is critical for the hormonal activity in rice. Replacement of the enol ether moiety by an alkoxy or imino ether resulted in a severe reduction in biological activity in rice. Moreover, yeast two-hybrid experiments using a possible SL receptor, DWARF14 (D14), and a repressor in the SL signaling pathway, DWARF53 (D53), showed that D14 can interact with D53 in the presence of (2'R) stereoisomers of SLs, but not (2'S) stereoisomers, suggesting that the stereostructure of SLs is crucial for the interaction of these proteins. When GR5, an AB-ring-truncated analog, was applied to the hydroponic culture medium, strong inhibition of shoot branching was observed both in rice and in Arabidopsis. However, GR5 was only weakly active when directly applied to the axillary buds of Arabidopsis. Our results indicate that the difference in plant species and application methods greatly influences the apparent SL biological activity.

    Original languageEnglish
    Pages (from-to)1059-1072
    Number of pages14
    JournalPlant and Cell Physiology
    Volume56
    Issue number6
    DOIs
    Publication statusPublished - 2014 Dec 22

    Keywords

    • Arabidopsis thaliana
    • Oryza sativa
    • Stereoisomer
    • Strigolactone

    ASJC Scopus subject areas

    • Physiology
    • Plant Science
    • Cell Biology

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  • Cite this

    Umehara, M., Cao, M., Akiyama, K., Akatsu, T., Seto, Y., Hanada, A., Li, W., Takeda-Kamiya, N., Morimoto, Y., & Yamaguchi, S. (2014). Structural requirements of strigolactones for shoot branching inhibition in rice and arabidopsis. Plant and Cell Physiology, 56(6), 1059-1072. https://doi.org/10.1093/pcp/pcv028