Speaker: Meixia Zhao, assistant professor in the University of Florida Department of Microbiology and Cell Science

Title: "Epigenetic silencing of transposable elements and the effects of transposon silencing on meiotic recombination in maize"

Abstract: Transposable elements (TEs) are ubiquitous DNA components in almost all eukaryotes. Although TEs are abundant, most of them are silenced by epigenetic pathways that involve small interfering RNAs, DNA methylation, and histone modifications. Our lab is interested in understanding how the epigenetic silencing of TEs is initiated at the first place, and how such silencing is maintained to next generations using maize hybrids of two mutants mop1 (mediator of paramutation1) and lbl1 (leafbladeless1), the wild type of which are involved in the small RNA biogenesis pathways. Because of the activity to move and the silencing effects of TEs, they have important impact on genome evolution, gene regulation, and chromatin structures. Our lab showed evidence that TEs can influence meiotic recombination genetically by inducing double-strand breaks when they are active, and epigenetically by introducing new methylated sequences near genes once they are silenced. Additionally, we are also examining whether meiotic recombination differs between males and females at both global and local scales, and whether local DNA sequences and chromatin structures play important roles in the distinction between male and female recombination. In addition to mop1 mutants, my group has been using several maize lines including the 25 parental inbreds of the maize nested association mapping (NAM) population to compare recombination frequency during male and female meiosis. Our data show that meiotic recombination differs substantially in different maize genetic backgrounds. Together, we aim to understand how active and silenced TEs affect meiotic recombination, and why recombination differs between sexes in maize.

Host: Sarah Anderson, Department of Genetics, Development and Cell Biology assistant professor

Sept. 13, 2022, GDCB Seminar flyer: Meixia Zhao