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This article in NSE

  1. Vol. 36 No. 1, p. 6-10
    Received: July 31, 2006

    * Corresponding author(s): ted.helms@ndsu.edu
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Educational Software for Mapping Quantitative Trait Loci (QTL)

  1. T. C. Helms *a and
  2. C. Doetkottb
  1. a Dep. of Plant Sciences, North Dakota State Univ., Fargo, ND 58105-5051
    b Information Technology Services, North Dakota State Univ., Fargo, ND 58105


This educational software was developed to aid teachers and students in their understanding of how the process of identifying the most likely quantitative trait loci (QTL) position is determined between two flanking DNA markers. The objective of the software that we developed was to: (1) show how a QTL is mapped to a position on a chromosome using a hands-on approach; (2) show how varying the guessed position of the QTL changes the mixture of QTL genotypes within each marker class. A least squares approach was used to determine the F statistic associated with each guessed QTL position between the flanking DNA markers. When the F statistic reaches a maximum value, the correct position of the QTL has been identified. The instructor identifies the true position of the QTL, while the students enter a guess as to the QTL position between flanking markers. The histograms generated by the software show the discrepancy between the true and guessed mixture of QTL genotypes within each of the nine marker classes. The output also shows how the design matrix and test statistic change as the guessed QTL position is altered. This software will aid the instructor in explaining how a QTL is mapped. Students will learn to associate the degree of recombination between markers and the QTL with resulting magnitude of the F statistic.

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