Monoallelic gene expression and its mechanisms

Although the majority of genes are expressed equally from both alleles, some genes are differentially expressed. Monoallelic gene expression, the differential gene expression of the alleles such as genomic imprinting, is reported in several organisms and plays significant roles in proper development and diversity in gene expression and phenotypic variation. Recent studies in flowering plants have greatly increased our understanding of the underlying mechanisms of monoallelic gene expression. They indicate that machineries of gene silencing such as DNA methylation, histone modifications, and noncoding RNAs function in monoallelic gene expression. A combination of genetics and high-throughput technologies expands the scope of study on monoallelic gene expression in flowering plants.

► A number of genes are predominantly expressed from only one of the alleles.
► Machineries for gene silencing act in the monoallelic gene expression in plants.
► Genomic imprinting is regulated by DNA methylation and/or histone modifications.
► A case of dominance relationships is regulated by small RNA mediated DNA methylation.