PI: Nathan M. Springer (University of Minnesota - Twin Cities)

CoPI: Matthew W. Vaughn (Cold Spring Harbor Laboratory)

Collaborator: Irina Makarevitch (Hamline University)

There is a growing interest in understanding how epigenetic variation might contribute to phenotypic variation. Epigenetic variation, heritable variation that is not due to sequence changes, has been observed in a number of biological phenomena. However, the prevalence and heritable behavior of epigenetic variation is not well understood. This project will study the prevalence, heritability and potential consequences of epigenetic variation in maize. Whole genome profiling of DNA methylation, histone H3 lysine 9 dimethylation and histone H3 lysine 27 trimethylation will be performed on several tissues of the maize inbred line B73 and on a set of 26 inbred lines that capture much of the diversity of maize. By focusing on this population it is possible to add epigenomic data to a wealth of existing data on genetic and phenotypic information. This will provide the potential to identify examples of epigenetic variation that contribute to phenotypic variation within a species. The project will also study how epigenetic differences are inherited in hybrids and recombinant inbred lines to assess the stability of epigenetic variation over multiple generations, which is critical to understanding the heritability of epigenetic variation and how it might be relevant to heritable phenotypic variation. In addition, relatively little is known about the role of epigenetics in natural variation. In order to provide a more detailed understanding of the role of epigenetics, it is critical to understand how this behavior is inherited and how this variation arises within a species. This project will develop tools that will enable epigenomic research in maize and will provide a framework for considering the frequency and stability of epigenetic variation among maize inbred lines and may provide a framework for integrating both genetic and epigenetic variation into plant breeding and improvement projects.

The research project will provide a set of excellent training opportunities for scientists at various stages of their careers. Undergraduate students from the University of Minnesota and Hamline University will be involved with the primary research and will receive mentoring from post-doctoral scientists and principal investigators. Postdoctoral scientists and a graduate student will perform hypothesis-based research that will provide experience with genomics and bioinformatics. In addition, the principal investigators have both shown a commitment to general outreach. Outreach efforts will include public education and K-12 teacher training. All data produced by this project will be made publicly available through established databases such as GEO (www.ncbi.nlm.nih.gov/geo/), Gramene (www.gramene.org) and MaizeGDB (www.maizegdb.org) as well as through a project website. The proposed project will also have broader impacts on other research. The information obtained in this project will influence studies of breeding and evolution. A greater understanding of the sources of variation within a species will influence the view of many fields.

Project Report

" was to define the sources of epigenomic variation in maize and to understand how this epigenomic variation may influence important plant traits. There is widespread interest in understanding how epigenetics contributes to phenotypic variation. Epigenetics describes heritable variation that is not solely attributable to genetic changes in DNA sequence. Epigenetic inheritance often involves chromatin modifications such as DNA methylation or histone modifications. In this project the genome-wide distribution of DNA methylation and two histone modifications (methylation of lysine 9 or 27 or histone H3) was profiled in different tissues and genotypes of maize. By documenting the distribution of these chromatin modifications at multiple developments time points and in multiple genotypes it was possible to examine the role of epigenetics in natural variation and in development. We found that methylation of H3K27 changes during development while DNA methylation tends to have more limited developmental differences. The profiling of DNA methylation in 50 diverse maize genotypes revealed numerous loci with natural variation for DNA methylation. These include examples of pure epigenetic variation as well as regions that have altered DNA methylation levels due to alterations in the genetic sequence. In particular, we discovered that a substantial portion of the natural variation in DNA methylation patterns may be attributable to the effects on transposable elements. The discovery of regions with variable levels of DNA methylation provided an opportunity to study the stability of inheritance for DNA methylation and the segregation patterns for DNA methylation. We found that DNA methylation is often inherited quite stably and often exhibits Mendelian segregation patterns. The successful completion of this project has provided insights into the dynamics of the maize epigenome. These results have been widely disseminated to the community via organism specific databases and the raw data generated by this project has been deposited at NCBI. The findings from this project have been broadly disseminated via a number of invited presentations and have led to 11 peer-reviewed publications.

Agency
National Science Foundation (NSF)
Institute
Division of Integrative Organismal Systems (IOS)
Application #
0922095
Program Officer
Diane Jofuku Okamuro
Project Start
Project End
Budget Start
2010-03-15
Budget End
2014-02-28
Support Year
Fiscal Year
2009
Total Cost
$1,678,620
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Type
DUNS #
City
Minneapolis
State
MN
Country
United States
Zip Code
55455