RESUMEN
DNA methylation is an epigenetic modification of the genome involved in the regulation of gene expression and modulation of chromatin structure. Plant genomes are widely methylated, and the methylation generally occurs on the cytosine bases through the activity of specific enzymes called DNA methyltransferases. On the other hand, methylated DNA can also undergo demethylation through the action of demethylases. The methylation landscape is finely tuned and assumes a pivotal role in plant development and evolution. This review illustrates different molecular aspects of DNA methylation and some plant physiological processes influenced by this epigenetic modification in model species, crops, and ornamental plants such as orchids. In addition, this review aims to describe the relationship between the changes in plant DNA methylation levels and the response to biotic and abiotic stress. Finally, we discuss the possible evolutionary implications and biotechnological applications of DNA methylation.
Asunto(s)
Metilación de ADN , Regulación de la Expresión Génica de las Plantas , ADN de Plantas/genética , ADN de Plantas/metabolismo , Epigénesis Genética , Genoma de Planta , Plantas/genética , Plantas/metabolismoRESUMEN
Genomic imprinting refers to the unequal expression of maternal and paternal alleles according to the parent of origin. This phenomenon is regulated by epigenetic controls and has been reported in placental mammals and flowering plants. Although conserved characteristics can be identified across a wide variety of taxa, it is believed that genomic imprinting evolved independently in animal and plant lineages. Plant genomic imprinting occurs most obviously in the endosperm, a terminally differentiated embryo-nourishing tissue that is required for seed development. Recent studies have demonstrated a close relationship between genomic imprinting and the development of elaborate defense mechanisms against parasitic elements during plant sexual reproduction. In this chapter, we provide an introductory description of genomic imprinting in plants, and focus on recent advances in our understanding of its role in endosperm development, the frontline of maternal and paternal epigenomes.