Plant Molecular Biology 39: 1299–1310, 1999.
© 1999 Kluwer Academic Publishers. Printed in the Netherlands.
The promoter of the strictosidine synthase gene from periwinkle confers
elicitor-inducible expression in transgenic tobacco and binds nuclear
factors GT-1 and GBF
, Alexandra S.W. Erven, Pieter B.F. Ouwerkerk, Frank L.H. Menke and
Institute of Molecular Plant Sciences, Clusius Laboratory, Wassenaarseweg 64, 2333 AL Leiden, Netherlands
author for correspondence);
present address: Centro de Biotecnologia do Estado do Rio Grande do Sul,
Universidade Federal do Rio Grande do Sul, P.O.Box 15005, CEP 91501-970, Porto Alegre, RS, Brazil
Received 8 September 1998; accepted in revised form 2 December 1998
Key words: Catharanthus roseus, DNA-binding protein, fungal elicitor, plant promoter, secondary metabolism,
terpenoid indole alkaloid
Strictosidine synthase (STR) is a key enzyme in the biosynthesis of terpenoid indole alkaloids. This class of
secondary metabolites harbours several pharmaceutically important compounds used, among other applications,
in cancer treatment. Terpenoid indole alkaloid biosynthesis and expression of biosynthetic genes including Str1is
induced by fungal elicitors. To identify elicitor-responsive regulatory promoter elements and trans-acting factors,
the single-copy Str1 gene was isolated from the subtropical plant species Catharanthus roseus (Madagascar peri-
winkle). Str1 upstream sequences conferred elicitor-responsive expression to the β-glucuronidase (gusA) reporter
gene in transgenic tobacco plants. Main enhancer sequences within the Str1 promoter region studied were shown
to be located between −339 and −145. This region and two other regions of the promoter bound the tobacco
nuclear protein factor GT-1. A G-box located around position −105 bound nuclear and cloned G-box-binding
factors (GBFs). A mutation that knocked out GBF binding had no measurable effect on expression, which indicates
that the G-box is not essential for the elicitor responsiveness of the Str1 promoter. No obvious homologies with
promoter elements identiﬁed in other elicitor-responsive genes were observed, suggesting that the Str1 gene may
depend on novel regulatory mechanisms.
Several plant secondary metabolite biosynthetic path-
ways were shown to be induced by stress conditions
[7, 17]. These responses are thought to reﬂect de-
fensive roles of the compounds synthesized, although
protective properties have only been demonstrated for
few secondary metabolites . Signals that evoke a de-
fence response are collectively referred to as elicitors.
Mechanisms of elicitor perception have received much
scientiﬁc attention [2, 7, 16]. Besides potential appli-
The nucleotide sequence data reported will appear in the
EMBL, GenBank and DDBJ Nucleotide Sequence Databases under
the accession number Y10182.
cations in disease resistance, knowledge of elicitor-
induced responses may open the way to increase the
production of secondary metabolites in plants or plant
cell cultures to commercially exploitable levels .
The terpenoid indole alkaloids form a class of sec-
ondary metabolites found in a limited number of plant
species. Several of these compounds have important
pharmaceutical applications, such as the anti-cancer
agents vincristine and vinblastine produced by the
subtropical plant Catharanthus roseus [17, 20].
Strictosidine synthase is a central enzyme in the
biosynthesis of terpenoid indole alkaloids. It cataly-
ses the condensation of tryptamine and secologanin
to form strictosidine, the precursor of all terpenoid