Planta Med 2007; 73(6): 605-610
DOI: 10.1055/s-2007-967199
Biochemistry and Molecular Biology
Original Paper
© Georg Thieme Verlag KG Stuttgart · New York

Enhancement of Cardenolide and Phytosterol Levels by Expression of an N-Terminally Truncated 3-Hydroxy-3-methylglutaryl CoA Reductase in Transgenic Digitalis minor

Ester Sales1 , Jesús Muñoz-Bertomeu2 , Isabel Arrillaga2 , Juan Segura2
  • 1Dpt. Agricultura y Economía Agraria, Escuela Politécnica Superior, Universidad de Zaragoza, Spain
  • 2Dpt. Biología Vegetal, Facultad de Farmacia, Universidad de Valencia, Spain
Further Information

Publication History

Received: February 14, 2007 Revised: March 28, 2007

Accepted: March 30, 2007

Publication Date:
22 May 2007 (online)

Abstract

Pathway engineering in medicinal plants attains a special significance in Digitalis species, the main industrial source of cardiac glycosides, steroidal metabolites derived from mevalonic acid via the triterpenoid pathway. In this work, the Arabidopsis thaliana HMG1 cDNA, coding the catalytic domain of 3-hydroxy-3-methylglutaryl CoA reductase (HMGR1S), a key enzyme of the MVA pathway, was expressed in the cardenolide-producing plant Digitalis minor. Transgenic plants were morphologically indistinguishable from control wild plants and displayed the same developmental pattern. Constitutive expression of HMG1 resulted in an increased sterol and cardenolide production in both in vitro- and greenhouse-grown plants. This work demonstrates that transgenic D. minor plants are a valuable system to study and achieve metabolic engineering of the cardenolide pathway and in consequence for the genetic improvement of Digitalis species.

Abbreviations

DMAPP: dimethylallyl diphosphate

HMG-CoA: 3-hydroxy-3-methyl glutaryl coenzyme A

HMGR: 3-hydroxy-3-methylglutaryl-CoA reductase

IPP: isopentenyl diphosphate

MVA: mevalonic acid

PCR: polymerase chain reaction

References

  • 1 Gershenzon J, Kreis W. Biochemistry of terpenoids: monoterpenes, sesquiterpenes, diterpenes, sterols, cardiac glycosides and steroid saponins. In: Wink M, editor Biochemistry of plant secondary metabolism. Sheffield; Sheffield Academic Press 1999: 222-9.
  • 2 Barkovich R, Liao J C. Metabolic engineering of isoprenoids.  Metab Eng. 2001;  3 27-39.
  • 3 Jørgensen K, Vinther-Rasmussen A, Morant M, Holm-Nielsen A, Bjarnholt N, Zagrobelny M. et al . Metabolon formation and metabolic channelling in the biosynthesis of plant natural products.  Curr Opin Plant Biol. 2005;  8 280-91.
  • 4 Wasserstrom J A, Aistrup J L. Digitalis: new actions for an old drug.  Am J Physiol Heart Circ Physiol. 2005;  289 H1781-93.
  • 5 Canter P H, Thomas H, Ernst E. Bringing medicinal plants into cultivation: opportunities and challenges for biotechnology.  Trends Biotechnol. 2005;  23 180-5.
  • 6 Kreis W, Hensel A, Stuhlemmer U. Cardenolide biosynthesis in foxglove.  Planta Med. 1998;  64 491-9.
  • 7 Herl V, Fischer G, Müller-Uri F, Kreis W. Molecular cloning and heterologous expression of progesterone 5β-reductase from Digitalis lanata Ehrh.  Phytochemistry. 2006;  67 225-31.
  • 8 Godoy-Hernández G C, Chappell J, Devarenne T P, García-Pineda E, Guevara-García A A, Lozoya-Gloria E. Antisense expression of HMG1 from Arabidopsis thaliana encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase, reduces isoprenoid production in transgenic tobacco plants.  J Plant Physiol. 1998;  153 415-24.
  • 9 Chappell J, Wolf F, Proulx J, Cuellar R, Saunders C. Is the reaction catalyzed by 3-hydroxy-3-methylglutaryl coenzyme A reductase a rate-limiting step for isoprenoid biosynthesis in plants?.  Plant Physiol. 1995;  109 1337-43.
  • 10 Schaller H, Grausem B, Benveniste P, Chye M L, Tan C T, Song Y H. et al . Expression of the Hevea brasiliensis (H.B.K.) Müll. Arg. 3-hydroxy-3-methylglutaryl-coenzyme A reductase 1 in tobacco results in sterol overproduction.  Plant Physiol. 1995;  109 761-70.
  • 11 Holmberg N, Harker M, Wallace A D, Clayton J C, Gibbard C L, Safford R. Co-expression of N-terminally truncated 3-hydroxy-3-methyl glutaryl CoA reductase and C24-sterol methyltransferase type 1 in transgenic tobacco enhances carbon flux towards end-product sterols.  Plant J. 2003;  36 12-20.
  • 12 Enfissi E MA, Fraser P D, Lois L M, Boronat A, Schuch W, Bramley P M. Metabolic engineering of the mevalonate and non-mevalonate isopentenyl diphosphate-forming pathways for the production of health-promoting isoprenoids in tomato.  Plant Biotechnol J. 2005;  3 17-27.
  • 13 Sales E, Segura J, Arrillaga I. Agrobacterium tumefaciens-mediated genetic transformation of the cardenolide-producing plant Digitalis minor .  Planta Med. 2003;  69 43-7.
  • 14 Lichius J J. Phytochemische Analyse seltener Digitalisarten (wie Digitalis subalpina Br.-Bl.) und reziproker Digitaliskreuzungen. Berlin; J. Cramer 1991.
  • 15 Lumbreras V, Campos N, Boronat A. The use of an alternative promoter in the Arabidopsis thaliana HMG1 gene generates an mRNA that encodes a novel 3-hydroxy-3-methylglutaryl coenzyme A reductase isoform with an extended N-terminally region.  Plant J. 1995;  8 541-9.
  • 16 Leivar P, González V M, Castel S, Trelease R N, López-Iglesias C, Arró M. et al . Subcellular localization of Arabidopsis 3-hydroxy-3-methylglutaryl-coenzyme A reductase.  Plant Physiol. 2005;  137 57-69Ž.
  • 17 Sales E, Nebauer S G, Arrillaga I, Segura J. Plant hormones and Agrobacterium tumefaciens strain 82.139 induce efficient plant regeneration in the cardenolide-producing plant Digitalis minor .  J Plant Physiol. 2002;  159 9-16.
  • 18 Tukey J W. Some selected quick and easy methods for statistical analysis.  Trans NY Acad Sci Ser II. 1953;  16 88-97.
  • 19 Bouvier F, Rahier A, Camara B. Biogenesis, molecular regulation and function of plant isoprenoids.  Prog Lipid Res. 2005;  44 357-429.
  • 20 Milek F, Reinhard E, Kreis W. Influence of precursors and inhibitors of the sterol pathway on sterol and cardenolide metabolism of Digitalis lanata EHRH.  Plant Physiol. 1997;  35 111-21.
  • 21 Kinney A J. Manipulating flux through plant metabolic pathways.  Curr Opin Plant Biol. 1998;  1 173-8.

Dr. Ester Sales

Dpt. Agricultura y Economía Agraria

Universidad de Zaragoza

Escuela Politécnica Superior

Ctra. Cuarte s/n

22071 Huesca

Spain

Phone: +34-974-239-325

Fax: +34-974-239-302

Email: esalesc@unizar.es