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2014_8_11_Freewalt_Thesis.pdf (1.34 MB)

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Creation of a High Density Soybean Linkage Map, QTL Mapping and the Effects of Marker Number, Population Size and Significance Threshold on Characterization of Quantitative Trait Loci

Freewalt, Keith
http://rave.ohiolink.edu/etdc/view?acc_num=osu1402656287

Abstract Details

2014, Master of Science, Ohio State University, Horticulture and Crop Science.
QTL mapping is a very important method for plant breeders to identify economically important loci. QTL mapping, along with a few other alternative methods, can be considered a necessary first step in marker assisted selection (MAS). By identifying economically valuable loci via QTL mapping the loci can then be selected for in elite backgrounds. In improving elite cultivars, the method has been most often useful for disease resistances that are controlled by one or few loci with large effect on the resistance phenotype. However, the rapid reduction in the cost of genotyping and sequencing could make selection of a large number of markers feasible. With the realized and foreseen advances in genotyping it is important to assess how to best be prepared to take advantage of technological advances. In order to study the advantages that will be offered in the near future by advances in genotyping we created a high density linkage map in soybean consisting of 2545 SNP markers. The linkage map is one of the first of its kind published in soybean and was necessary for the study of genotyping advancements. The linkage map was created from 354 RIL. It was resampled randomly by line numbers of 95, 190 and 285. Markers were resampled randomly at 10, 25, 40 and 55 markers per chromosome. Significance threshold was defined at 0.05 and 0.25 by permutation test. The three traits tested were plant height, leaf height to width ratio and 100 seed weight which represent a range of quantitative traits with no direct correlation. We found that line number, the number of markers and significance threshold all play important roles during QTL mapping. Line number and significance threshold have the greatest effects followed by marker number. In addition, QTL mapping was conducted for seed projected area, 100 seed weight, seed width, seed length and seed width to length ratio. Two QTL for seed width and one QTL for seed roundness, representing two distinct loci, were newly detected in this study. One QTL x QTL interaction was newly detected in this study. An additional 13 QTL co-located with previously reported QTL for the same traits or for traits that are highly correlated to traits mapped in this study.
Leah McHale (Advisor)
83 p.
Agriculture; Genetics; Plant Sciences
QTL; Soybean; Resampling; Seed Trait;

Recommended Citations

Citations

  • Freewalt, K. (2014). Creation of a High Density Soybean Linkage Map, QTL Mapping and the Effects of Marker Number, Population Size and Significance Threshold on Characterization of Quantitative Trait Loci [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1402656287

    APA Style (7th edition)

  • Freewalt, Keith. Creation of a High Density Soybean Linkage Map, QTL Mapping and the Effects of Marker Number, Population Size and Significance Threshold on Characterization of Quantitative Trait Loci. 2014. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1402656287.

    MLA Style (8th edition)

  • Freewalt, Keith. "Creation of a High Density Soybean Linkage Map, QTL Mapping and the Effects of Marker Number, Population Size and Significance Threshold on Characterization of Quantitative Trait Loci." Master's thesis, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1402656287

    Chicago Manual of Style (17th edition)

osu1402656287
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This open access ETD is published by The Ohio State University and OhioLINK.
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