Plant Molecular Biology

, Volume 37, Issue 5, pp 763–772 | Cite as

Conserved structure and function of the Arabidopsis flowering time gene CONSTANS in Brassica napus

  • Laurian S. Robert
  • Frances Robson
  • Andrew Sharpe
  • Derek Lydiate
  • George Coupland


The Arabidopsis thaliana CONSTANS (CO) gene which promotes flowering in long days was recently isolated by chromosome walking. The mapping of QTLs controlling flowering time in Brassica species has identified genomic regions that contain homologues of the CO gene. Four genes homologous to the Arabidopsis CO gene were isolated from a pair of homoeologous loci in each of two doubled-haploid Brassica napus lines displaying different flowering times, N-o-1 and N-o-9. The four genes, BnCOa1, BnCOa9, BnCOb1 and BnCOb9, are located on linkage groups N10 and N19, and are highly similar to each other and to the Arabidopsis CO gene. Two regions of the proteins are particularly well conserved, a N-terminal region with two putative zinc fingers and a C-terminal region which may contain a nuclear localization signal. All four genes appear to be expressed in B. napus. The BnCOa1 allele was shown to complement the co-2 mutation in Arabidopsis in a dosage-dependent manner causing earlier flowering than in wild type under both long- and short-day conditions.

Arabidopsis thaliana Brassica napus constans flowering zinc finger 


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Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • Laurian S. Robert
    • 1
  • Frances Robson
    • 2
  • Andrew Sharpe
    • 3
  • Derek Lydiate
    • 3
  • George Coupland
    • 2
  1. 1.Eastern Cereal and Oilseed Research Centre, Central Experimental FarmOttawaCanada
  2. 2.Molecular Genetics Department, John Innes Centre, Colney LaneNorwichUK
  3. 3.Brassica and Oilseeds Research Department, John Innes Centre, Colney LaneNorwichUK

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