Expression and Regulation Of Duplicated Genes In Soybean

Soybean experienced two relatively recent duplication events for which the divergence times of paralogs have been esteemed to be ~55 and 13 MYA. Previously, we have shown that in any one tissue 40-50% of duplicated genes show evidence of transcriptional divergence, where one copy is more highly expressed than the other. Nearly all of these genes are under purifying selection. A number of processes could have led to transcriptional changes in duplicated genes (e.g. transposable elements or changes in promoters). We have been focussing on the possible contribution of epigenetic changes to differences in transcriptional differences between paralogs. We first established a baseline of DNA methylation in soybean across tissues from which to analyze sets of genes. From this, at a global level, we do see changes in methylation patterns such that differentially expressed paralogs have increased methylation in the promoter as compared to paralogs that are not differentially expressed. However, both the under and over expressed copies have increased methylation as compared to those that are not differentially expressed. Since the same evolutionary processes do not likely play similar role in all duplicated genes, we are investigating at level of subsets of genes the role of DNA methylation and/or transposable elements in establishing different transcriptional activities for paralogous genes.