Epigenome and Abiotic Stress Tolerance in Plants

Epigenome refers to the genomic content of a cell layered with all the covalent/noncovalent modifications on the DNA and histones. Remodeling of the chromatin is induced by these changes in response to environmental or developmental signals without any change in the underlying nucleotide sequence. These modifications are stably inherited through mitotic and meiotic divisions. Every differentiated cell type possesses a characteristic epigenome that is dynamic and differs from the epigenome of neighboring cell type, while the genotype of the cells remains constant. DNA methylation, histone modifications, inclusion of histone variants in the nucleosomes, small RNAs and their effector molecules all contribute towards changing the landscape of the epigenomes. Valuable insights into genomic distribution of methyl groups has been obtained by employing various high throughput technologies. Orchestered changes in the epigenetic landscape also occurs in response to abiotic stress. Plants respond to these stresses by modulating the expression of stress-regulated genes through covalent/noncovalent modifications of chromatin. This chapter highlights the contribution of epigenetic modifications in shaping the epigenome and mediating gene regulation in response to abiotic stress.