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Theoretical and Applied Genetics

, Volume 94, Issue 6–7, pp 810–820 | Cite as

Multiple marker mapping of quantitative trait loci in an outbred pedigree of loblolly pine

  • S. A. Knott
  • D. B. Neale
  • M. M. Sewell
  • C. S. Haley

Abstract

 A multiple marker least squares approach is presented for the analysis of a single three-generation pedigree for quantitative trait locus (QTL) characterisation. It is an extension of the approach by Haley et al. (1994) to the situation where grandparents cannot be assumed to be homozygous at QTLs for the trait of interest. The method is applied to the analysis of wood specific gravity in loblolly pine (Pinus taeda L.). Within a similar framework, a series of preliminary analyses are carried out, followed by a more detailed search of the genome for one or more QTLs. The preliminary analyses provide information about whether the contribution from each linkage group appears to be polygenic, localised to a small region (e.g. a single QTL) or oligogenic (i.e. several QTLs). Significance levels are obtained using a permutation test that uses the observed phenotypes and marker genotypes. The conclusion of these analyses is that in this pedigree single QTLs with very large effect on wood specific gravity do not appear to be segregating, although there is evidence for QTLs with small effect. Finally, in order to assess the potential power of this pedigree, we simulated QTLs within the framework of the actual marker data. As expected, QTL effects would need to be large to be reliably detected in this study, and the power to detect QTLs varies at different positions in the genome depending on the level of information in the local markers.

Key words Quantitative trait loci Outcrossing Pinus taeda L. 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • S. A. Knott
    • 1
  • D. B. Neale
    • 2
  • M. M. Sewell
    • 2
  • C. S. Haley
    • 3
  1. 1.Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JT, UKGB
  2. 2.USDA Forest Service, Pacific Southwest Research Station, Institute of Forest Genetics, Albany, California 94710, USAUS
  3. 3.Roslin Institute (Edinburgh), Midlothian, EH25 9PS, UKGB

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