Transgenic Research

, Volume 17, Issue 4, pp 573–585 | Cite as

Enhancing the carotenoid content of Brassica napus seeds by downregulating lycopene epsilon cyclase

  • Bianyun Yu
  • Derek J. Lydiate
  • Lester W. Young
  • Ulrike A. Schäfer
  • Abdelali HannoufaEmail author
Original Paper


The accumulation of carotenoids in higher plants is regulated by the environment, tissue type and developmental stage. In Brassica napus leaves, β-carotene and lutein were the main carotenoids present while petals primarily accumulated lutein and violaxanthin. Carotenoid accumulation in seeds was developmentally regulated with the highest levels detected at 35–40 days post anthesis. The carotenoid biosynthesis pathway branches after the formation of lycopene. One branch forms carotenoids with two β rings such as β-carotene, zeaxanthin and violaxanthin, while the other introduces both β- and ε-rings in lycopene to form α-carotene and lutein. By reducing the expression of lycopene ε-cyclase (ε-CYC) using RNAi, we investigated altering carotenoid accumulation in seeds of B. napus. Transgenic seeds expressing this construct had increased levels of β-carotene, zeaxanthin, violaxanthin and, unexpectedly, lutein. The higher total carotenoid content resulting from reduction of ε-CYC expression in seeds suggests that this gene is a rate-limiting step in the carotenoid biosynthesis pathway. ε-CYC activity and carotenoid production may also be related to fatty acid biosynthesis in seeds as transgenic seeds showed an overall decrease in total fatty acid content and minor changes in the proportions of various fatty acids.


Carotenoids Lycopene ε-cyclase Brassica napus Seeds RNAi silencing 



We are grateful to Mr. Delwin Epp for technical assistance with B. napus tissue culture and Dr. Branimir Gjetvaj for assistance with the microarray analysis. We thank Drs. Kevin Falk, Kevin Rozwadowski and Bhinu V.S. for critical reading of the manuscript, and for helpful suggestions. Funding for this project was provided by the Saskatchewan Agriculture Development Fund.


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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Bianyun Yu
    • 1
  • Derek J. Lydiate
    • 1
  • Lester W. Young
    • 1
    • 2
  • Ulrike A. Schäfer
    • 1
  • Abdelali Hannoufa
    • 1
    Email author
  1. 1.Agriculture and Agri-Food CanadaSaskatoon Research CentreSaskatoonCanada
  2. 2.Department of Plant SciencesUniversity of SaskatchewanSaskatoonCanada

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