Molecular Genetics and Genomics

, Volume 268, Issue 1, pp 122–129

QTL analyses reveal clustered loci for accumulation of major provitamin A carotenes and lycopene in carrot roots

  •  C. Santos
  •  P. Simon
Original Paper

DOI: 10.1007/s00438-002-0735-9

Cite this article as:
Santos, C. & Simon, P. Mol Gen Genomics (2002) 268: 122. doi:10.1007/s00438-002-0735-9

Abstract.

QTLs associated with products of the carotenoid pathway, including lycopene and the provitamin A carotenes α- and β-carotene, were investigated in two unrelated F2 carrot populations, derived from crosses between orange cultivated B493 and white wild QAL (Population 1), and orange cultivated Brasilia and dark-orange cultivated HCM (Population 2). The mapping populations of 160 and 180 individuals, respectively, were analyzed with single-marker and interval-mapping statistical approaches, using coupling linkage maps for each parent. Single markers were selected for further analysis based on the Wilcoxon sum-rank non-parametric test. Interval mapping performed with Population 2 detected four, eight, three, one and five putative QTLs associated with accumulation of ξ-carotene, α-carotene, β-carotene, lycopene and phytoene, respectively. Among these, the major QTLs explained 13.0%, 10.2%, 13.0%, 7.2% and 10.2% of total phenotypic variation. In Population 1 single-marker analysis identified loci explaining up to 13.8%, 6.8%, 19.3%, 5.7%, and 17.5%, respectively, of total phenotypic variation for these same carotenoids. Overall analysis demonstrated clustering of these QTLs associated with the carotenoid pathway: the AFLP loci AACCAT178-Q and AAGCAG233-Q, on linkage group 5, explained 17.8%, 22.8% and 23.5% of total phenotypic variation for ζ-carotene, phytoene and β-carotene in Population 1. Two major clusters of QTLs, with LOD scores greater than 1.8, mapped to intervals no larger than 2 cM for ζ-carotene, β-carotene, α-carotene and lycopene on linkage group 3, and for ζ-carotene and phytoene on linkage group 9, and these explained 3.7% to 13.0% of variation for each carotenoid product. Thus, these results suggest that clustering of related pathway loci is favored during evolution, since closely linked "pathway mates" are not easily separated by recombination.

Biochemical pathway Daucus carota L. Linked pathway genes Wilcoxon sum-rank test 

Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  •  C. Santos
    • 1
  •  P. Simon
    • 2
  1. 1.Plant Breeding and Plant Genetics Program, University of Wisconsin, 1575 Linden Drive, Madison, WI 53706, USA
  2. 2.USDA-Agricultural Research Service, Vegetable Crops Research Unit Department of Horticulture, 1575 Linden Drive, University of Wisconsin, Madison, WI 53706
  3. 3.Present address: Embrapa (Brazilian Agricultural Research Corporation) Semi-Arido, Caixa Postal 23.56300-970, Petrolina PE, Brazil