Carlactone is an endogenous biosynthetic precursor for strigolactones

Yoshiya Seto, Aika Sado, Kei Asami, Atsushi Hanada, Mikihisa Umehara, Kohki Akiyama, Shinjiro Yamaguchi

    Research output: Contribution to journalArticlepeer-review

    167 Citations (Scopus)

    Abstract

    Strigolactones (SLs) are a class of terpenoid plant hormones that regulate shoot branching as well as being known as root-derived signals for symbiosis and parasitism. SL has tricyclic-lactone (ABCring) and methyl butenolide (D-ring), and they are connected through an enol ether bridge. Recently, a putative biosynthetic intermediate called carlactone (CL), of which carbon skeleton is in part similar to those of SLs, was identified by biochemical analysis of three biosynthetic enzymes, DWARF27, CAROTENOID CLEAVAGE DIOXYGENASE 7 (CCD7), and CCD8 in vitro. However, CL has never been identified from plant tissues, and the conversion of CL to SLs has not been proven in vivo. To address these questions, we chemically synthesized 13C-labeled CL. We show that 13C-labeled CL is converted to (-)-[13C]-2′-epi-5- deoxystrigol ((-)-2′-epi-5DS) and [13C]-orobanchol, endogenous SLs in rice, in the dwarf10 mutant, which is defective in CCD8. In addition, we successfully identified endogenous CL by using liquid chromatography-quadrupole/ time-of-flight tandem mass spectrometry in rice and Arabidopsis. Furthermore, we determined the absolute stereochemistry of endogenous CL to be (11R)-configuration, which is the same as that of (-)-2′-epi-5DS at the corresponding position. Feeding experiments showed that only the (11R)-isomer of CL, but not the (11S)-isomer, was converted to (-)-2′-epi-5DS in vivo. Taken together, our data provide conclusive evidence that CL is an endogenous SL precursor that is stereospecifically recognized in the biosynthesis pathway.

    Original languageEnglish
    Pages (from-to)1640-1645
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Volume111
    Issue number4
    DOIs
    Publication statusPublished - 2014 Jan 28

    Keywords

    • Cytochrome P450
    • Phosphate deficiency

    ASJC Scopus subject areas

    • General

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