Planta

, Volume 222, Issue 3, pp 458–471

Comparative macroarray analysis of morphine containing Papaver somniferum and eight morphine free Papaver species identifies an O-methyltransferase involved in benzylisoquinoline biosynthesis

  • Jörg Ziegler
  • María Luisa Diaz-Chávez
  • Robert Kramell
  • Christian Ammer
  • Toni M. Kutchan
Original Article

DOI: 10.1007/s00425-005-1550-4

Cite this article as:
Ziegler, J., Diaz-Chávez, M.L., Kramell, R. et al. Planta (2005) 222: 458. doi:10.1007/s00425-005-1550-4

Abstract

Benzylisoquinoline alkaloids constitute a group of about 2,500 structures and are mainly produced by plants of the order Ranunculales. But only the opium poppy, Papaver somniferum, and Papaver setigerum are able to produce morphine. In this study, we started to investigate by gene expression analysis the molecular basis for this exceptional biosynthetic ability. A sequencing project from P. somniferum seedlings was initiated using a method based on the amplified fragment length polymorphism technique that resulted in 849 UniGenes. These cDNAs were analysed on macroarrays for differential expression between morphine-containing P. somniferum plants and eight other Papaver species, which accumulate other benzylisoquinolines instead of morphine. Three cDNAs showing increased expression in P. somniferum compared to all the other Papaver species were identified. Whereas two showed no significant homology to any known protein, one putatively encoded an O-methyltransferase. Analysis of substrate specificity of the heterologously expressed protein and mass spectrometric identification of the enzymatic products identified this protein as S-adenosyl-L-methionine:(R,S)-3′-hydroxy-N-methylcoclaurine 4′-O-methyltransferase (EC 2.1.1.116). Unlike other O-methyltransferases of different positional specificities implicated in benzylisoquinoline metabolism, the enzyme only accepted tetrahydroxylated tetrahydrobenzylisoquinolines as substrates; methylation was tolerated only at the 6-hydroxy position.

Keywords

(R, S)-3′-hydroxy-N-methylcoclaurine 4′-O-methyltransferase Alkaloid biosynthesis Opium poppy Papaver somniferum Macroarray Expressed sequence tags 

Abbreviations

4′-OMT

(R,S)-3′-Hydroxy-N-methylcoclaurine 4′-O-methyltransferase

6-OMT

Norcoclaurine 6-O-methyltransferase

7-OMT

Reticuline 7-O-methyltransferase

AdoMet

S-adenosyl-L-methionine

AFLP

Amplified fragment length polymorphism

BBE

Berberine bridge enzyme

COR

Codeinone reductase

Cyp80b1

(S)-N-Methylcoclaurine 3′-hydroxylase

EST

Expressed sequence tag

ESI-MS

Electrospray ionization-mass spectrometry

RACE

Rapid amplification of cDNA ends

SalAT

Salutaridinol 7-O-acetyltransferase

TOF

Time of flight

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Jörg Ziegler
    • 1
  • María Luisa Diaz-Chávez
    • 1
  • Robert Kramell
    • 1
  • Christian Ammer
    • 1
  • Toni M. Kutchan
    • 1
  1. 1.Leibniz-Institut für PflanzenbiochemieHalle/SaaleGermany

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