| Popis: |
Following whole genome duplication, one subgenome of maize retains more ancestral genes (dominant genome) than the other subgenome (recessive subgenome), and the genes in the dominant genome are expressed at a higher level than those in the recessive genome. I characterized evolutionary rates, transcriptional levels, methylation levels, histone modifications, and chromatin accessibility between the two maize subgenomes in different genomic locations. I identified stronger purifying selection and higher transcriptional levels for genes in the dominant subgenome than those in the recessive subgenome in chromosomal arms, but not in pericentromeric regions. This trend is alsoreflected in TE densities, CHH methylation levels, silencing histone marks (H3K9me2),active histone marks (H3Kac), and accessible chromatin regions (ACRs) in chromosomal arms. Finally, the retention and deletion of conserved ACRs are associated with the higher transcriptional levels of their potential target genes in the dominant subgenome. These results demonstrate that DNA methylation level, histone modification and regulatory elements contribute to the evolutionary and transcriptional differentiation of the two subgenomes in chromosomal arms of maize. |
