Epigenetic Concepts and Relationships with Polyploidy
Dilek GÖGEN*, Esin Oluk
Polyploidy or whole genome duplication (WGD) has been an important genomic feature for all eukaryotes, especially many plants and some animals. It is produced by duplication of a single genome (autopolyploid) or a combination of two or more different genomes (allopolyploid). Available data from the study of synthetic (nascent or man-made) plant allopolyploids have documented dynamic and stochastic changes in genomic organization and gene expression, including sequence elimination, interchromosomal exchanges, cytosine methylation, gene repression, new activation. The co-occurrence of polyploidy demonstrated an evolutionary advantage to having more than one set of genetic materialfor adaptive evolution. Thus, new allopolyploids were required to establish a harmonious relationship between foreign cytoplasm and nuclei and between two different genomes, resulting in rapid changes in genome structure, gene expression and developmental traits such as fertility, inbreeding, apomixis, flowering time and hybrid vigor. Convincing evidence has been found that changes in DNA sequence, cisand trans-acting effects, chromatin modifications, RNA-mediated pathways and regulatory networks modulate differential expression of homologous genes and phenotypic variation, which may facilitate adaptive evolution in polyploid plants and domestication in crops.