SEMINAR: Transposons as sources of genetic and epigenetic variation in crop genomes

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Date/Time:Thursday, 14 Sep 2017 from 4:10 pm to 5:10 pm
Location:2050 Agronomy Hall
Channel:Agronomy Department
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Nathan M. Springer, McKnight Presidential Endowed Professor University of Minnesota.

Refreshments at 3:30PM in the Agronomy Hall common areas and after the seminar

Transposons account for the majority of the genome in most crop species. We often think of these transposons as either "junk" or insertional mutagens. However, there are also examples of transposon insertions that can influence gene expression through genetic or epigenetic mechanisms. I will describe several on-going studies that seek to understand how transposons influence the methylome and transcriptome in maize. The maize methylome is heavily shaped by patterns of DNA methylation surrounding genes and transposons. Many transposons are methylated at very high levels. A comparison of the methylome of different inbred lines of maize has identified thousands of regions with variable methylation in different genotypes. We have found that about half of these differentially methylated regions can be attributed to methylation that is influenced by nearby transposons. Only a subset of transposon families are associated with the potential for spreading of DNA methylation to nearby regions and these transposon families are often associated with silencing of nearby genes when they are inserted in promoter regions. We have also been studying the expression of transposons and genes. A subset of transposon families are expressed and many of these exhibit tissue-specific patterns of expression. We also have documented several transposon families that may provide novel regulatory elements that could influence the response of nearby genes to environmental conditions. These studies highlight the diverse ways in which transposons are shaping crop genomes and providing important sources of natural variation.