Meiotic recombination is an important phenomenon that results in genetic diversity and accurate segregation of homologous chromosomes. Mishaps in meiotic recombination can have severe consequences in humans, including pregnancy loss, congenital disorders, and other genetic diseases. In all eukaryotes, meiotic recombination is initiated by double-stranded breaks (DSBs) and is finished by the repair of those DSBs. There is evidence that transposable elements (TEs) can influence recombination genetically by inducing DSBs during transposition. The objective of this project was to determine if the DSBs caused by the transposition of Mutator (Mu) elements would increase recombination. Our hypothesis is that active TEs in maize would stimulate an increase in recombination. To test the hypothesis, we used two backcrossed (BC1) populations derived from parents with a large number of active and silenced Mu elements. This allowed us to compare recombination at a particular locus when Mu elements were active or silenced. We compared recombination frequency at the Les28 locus between the BC1 population derived from the plant carrying active Mu elements and the BC1 population derived from the plant carrying silenced Mu elements. Our data show that at the Les28 locus, genetic distance (18.3 centimorgans, cM) in the active Mu lines is much higher than that in the silenced Mu lines (12.7 cM), suggesting that active Mu TEs do increase recombination. Next, we will identify all the other Mu insertions in the active and silenced lines, and compare recombination frequency around them to determine the role of active and silenced TEs in meiotic recombination.
Author: Celine Thormann, Biology and Spanish Major
Advisor: Meixia Zhao, Biology
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