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The basic helix-loop-helix transcription factor BIS2 is essential for monoterpenoid indole alkaloid production in the medicinal plant Catharanthus roseus

Author:
  • Alex Van Moerkercke
  • Priscille Steensma
  • Ivo Gariboldi
  • Javiera Espoz
  • Purin C Purnama
  • Fabian Schweizer
  • Karel Miettinen
  • Robin Vanden Bossche
  • Rebecca De Clercq
  • Johan Memelink
  • Alain Goossens
Publishing year: 2016-10
Language: English
Pages: 3-12
Publication/Series: Plant Journal
Volume: 88
Issue: 1
Document type: Journal article
Publisher: Wiley-Blackwell

Abstract english

Monoterpenoid indole alkaloids (MIAs) are produced as plant defence compounds. In the medicinal plant Catharanthus roseus, they comprise the anticancer compounds vinblastine and vincristine. The iridoid (monoterpenoid) pathway forms one of the two branches that feed MIA biosynthesis and its activation is regulated by the transcription factor (TF) basic helix-loop-helix (bHLH) iridoid synthesis 1 (BIS1). Here, we describe the identification and characterisation of BIS2, a jasmonate (JA)-responsive bHLH TF expressed preferentially in internal phloem-associated parenchyma cells, which transactivates promoters of iridoid biosynthesis genes and can homodimerise or form heterodimers with BIS1. Stable overexpression of BIS2 in C. roseus suspension cells and transient ectopic expression of BIS2 in C. roseus petal limbs resulted in increased transcript accumulation of methylerythritol-4-phosphate and iridoid pathway genes, but not of other MIA genes or triterpenoid genes. Transcript profiling also indicated that BIS2 expression is part of an amplification loop, as it is induced by overexpression of either BIS1 or BIS2. Accordingly, silencing of BIS2 in C. roseus suspension cells completely abolished the JA-induced upregulation of the iridoid pathway genes and subsequent MIA accumulation, despite the presence of induced BIS1, indicating that BIS2 is essential for MIA production in C. roseus.

Keywords

  • Biochemistry and Molecular Biology
  • Basic Helix-Loop-Helix Transcription Factors
  • Catharanthus
  • Gene Expression Regulation, Plant
  • Indole Alkaloids
  • Plant Proteins
  • Plants, Medicinal
  • Journal Article

Other

Published
  • ISSN: 1365-313X
Alex Van Moerkercke
E-mail: alex [dot] van_moerkercke [at] biol [dot] lu [dot] se

Postdoctoral fellow

Molecular Cell Biology

+46 46 222 49 49

B-A308

Sölvegatan 35, Lund

4

Research group

Plant Biology

Projects

 

Postdoc host

Olivier Van Aken