Planta

, Volume 232, Issue 3, pp 691–699

Overexpression of the rice carotenoid cleavage dioxygenase 1 gene in Golden Rice endosperm suggests apocarotenoids as substrates in planta

  • Andrea Ilg
  • Qiuju Yu
  • Patrick Schaub
  • Peter Beyer
  • Salim Al-Babili
Original Article

Abstract

Carotenoids are converted by carotenoid cleavage dioxygenases that catalyze oxidative cleavage reactions leading to apocarotenoids. However, apocarotenoids can also be further truncated by some members of this enzyme family. The plant carotenoid cleavage dioxygenase 1 (CCD1) subfamily is known to degrade both carotenoids and apocarotenoids in vitro, leading to different volatile compounds. In this study, we investigated the impact of the rice CCD1 (OsCCD1) on the pigmentation of Golden Rice 2 (GR2), a genetically modified rice variety accumulating carotenoids in the endosperm. For this purpose, the corresponding cDNA was introduced into the rice genome under the control of an endosperm-specific promoter in sense and anti-sense orientations. Despite high expression levels of OsCCD1 in sense plants, pigment analysis revealed carotenoid levels and patterns comparable to those of GR2, pleading against carotenoids as substrates in rice endosperm. In support, similar carotenoid contents were determined in anti-sense plants. To check whether OsCCD1 overexpressed in GR2 endosperm is active, in vitro assays were performed with apocarotenoid substrates. HPLC analysis confirmed the cleavage activity of introduced OsCCD1. Our data indicate that apocarotenoids rather than carotenoids are the substrates of OsCCD1 in planta.

Keywords

Apocarotenoids Carotenoids Carotenoid cleavage dioxygenase Golden Rice Endosperm 

Abbreviations

CCD1

Carotenoid cleavage dioxygenase 1

GR

Golden Rice

Gt1

Glutelin 1 promoter

Supplementary material

425_2010_1205_MOESM1_ESM.pdf (15 kb)
Supplementary material 1 (PDF 14 kb)

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Andrea Ilg
    • 1
  • Qiuju Yu
    • 1
  • Patrick Schaub
    • 1
  • Peter Beyer
    • 1
  • Salim Al-Babili
    • 1
  1. 1.Faculty of Biology, Institute of Biology IIAlbert-Ludwigs University of FreiburgFreiburgGermany

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