The first step of gibberellin biosynthesis in pumpkin is catalyzed by at least two copalyl diphosphate synthases encoded by differentially regulated genes

Maria W. Smith, Shinjiro Yamaguchi, Tahar Ait-Ali, Yuji Kamiya

    Research output: Contribution to journalArticlepeer-review

    49 Citations (Scopus)

    Abstract

    The first step in gibberellin biosynthesis is catalyzed by copalyl diphosphate synthase (CPS) and enf-kaurene synthase. We have cloned from pumpkin (Cucurbita maxima L.) two cDNAs, CmCPS1 and CmCPS2, that each encode a CPS. Both recombinant fusion CmCPS proteins were active in vitro. CPS are translocated into plastids and processed by cleavage of transit peptides. For CmCPS1 and CmCPS2, the putative transit peptides cannot exceed the first 99 and 107 amino acids, respectively, because longer N-terminal deletions abolished activity. Levels of both CmCPS transcripts were strictly regulated in an organ-specific and developmental manner. Both transcripts were almost undetectable in leaves and were abundant in petioles. CmCPS1 transcript levels were high in young cotyledons and low in roots. In contrast, CmCPS2 transcripts were undetectable in cotyledons but present at significant levels in roots. In hypocotyls, apices, and petioles, CmCPS1 transcript levels decreased with age much more rapidly than those of CmCPS2. We speculate that CmCPS1 expression is correlated with the early stages of organ development, whereas CmCPS2 expression is correlated with subsequent growth. In contrast, C. maxima enf-kaurene synthase transcripts were detected in every organ at almost constant levels. Thus, enf-kaurene biosynthesis may be regulated through control of CPS expression.

    Original languageEnglish
    Pages (from-to)1411-1419
    Number of pages9
    JournalPlant physiology
    Volume118
    Issue number4
    DOIs
    Publication statusPublished - 1998

    ASJC Scopus subject areas

    • Physiology
    • Genetics
    • Plant Science

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