The Genetics of Phenotypic Variation in Arabidopsis thaliana

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Title: The Genetics of Phenotypic Variation in Arabidopsis thaliana
Author: Ehrenreich, Ian Michael
Advisors: Michael D. Purugganan, Committee Chair
Stephanie E. Curtis, Committee Co-Chair
Greg C. Gibson, Committee Member
Robert G. Franks, Committee Member
Abstract: All organisms exhibit substantial quantitative trait variation within populations. Such variation is important because it can affect fitness and serve as the substrate for adaptive evolution. Identifying the quantitative trait genes (QTGs) responsible for phenotypic variation is necessary to understand the mechanisms that generate trait variation and to determine the historical action of natural selection on quantitative traits and QTGs. However, in most complex organisms, the genetic mapping of QTGs is difficult and presently not feasible to do systematically at a gene-level resolution. Model organisms that are both tractable in the laboratory and complex developmentally can serve as trial systems for developing broadly applicable methods for QTG mapping. Using the plant genetic model Arabidopsis thaliana, I have attempted to map QTGs for ecologically-significant quantitative traits – shoot branching and flowering time – through a combination of forward and reverse genetic methods. Three main research projects are reported here: i) candidate gene association mapping and linkage mapping of shoot branching; ii) regulatory network-wide candidate gene association mapping of flowering time; and iii) a survey of intra- and interspecific genetic variation at nearly half of the microRNAs (miRNAs) and their binding sites in the genome. These studies have identified strong candidate QTGs for traits that are determinants of A. thaliana fitness in the wild. I synthesize my results with those of other researchers in this area to highlight the achievements, future promise, and looming challenges for statistical genetics in terms of elucidating the genetic basis of trait variation.
Date: 2008-11-17
Degree: PhD
Discipline: Genetics

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