Project Number: 3625-21220-004-33
Project Type: Specific Cooperative Agreement

Start Date: Dec 19, 2011
End Date: Sep 30, 2014

Objective:
1. Epigenetic analysis in the form of methylation data and histone modification data will be collected on one subset of a NAM population. This will be the same population from which RNA-Seq gene expression data will be collected; 2. Loci identified for which epigenetic changes appear to be correlated to agronomic traits will be verified in other NAM populations.

Approach:
Seventy lines will be sequenced to 20x coverage for the determination of methyl cytosines. DNA from the 70 lines will be treated using sodium bisulfate conversion kits that will then be sequenced using an Illumina HiSeq, 1 line per sample (70 lines of sequencing). This will be done in two replicates to reduce sample variation and provide more confidence in ‘epialleles’ (the epigenetic variants of the same gene). Seventy lines will be sequenced to 5x using ChIP pulldowns for H3K9-methylation. Commercial antibodies for H3K9 methylation will be used to pull down DNA associated with this epigenetic mark. DNA will be sequenced to 5x per accession, four accessions per lane. Seventy lines sequenced to 5x using ChIP pulldowns for H3K27-methylation. Commercial antibodies for H3K27 methylation will be used to pull down DNA associated with this epigenetic mark. DNA will be sequenced to 5x per accession, four accessions per lane. Informatic analysis of data to identify the epialleles correlated with agronomic traits. Collaboration with University of Delaware will allow the public access of all the data generated. In addition, the informaticists and postdoc on this project will analyze the data to find epigenetic marks, epialleles, that appear to be correlated with specific agronomic traits as identified by ARS. We will confirm the association of putative epialleles with agronomic traits. The putative epialleles are not really useful until they are validated and the NAM populations provide a unique opportunity for validation. Validation will be done using PCR to amplify the putative alleles. We will then sequence those amplicons in an indexed format. We will first focus on replicates of the initial population we targeted, then expand to other NAM subpopulations to determine how robust these epialleles are.