Regulation and modification of the epigenome for enhanced salinity tolerance in crop plants

Abstract

Histone modifications (acetylation, méthylation, phosphorylation, etc.), histone variants, regulatory RNAs, and DNA methylation represent the functional elements of epigenetics. They serve as a basis for regulating biological processes such as flowering and germination, as well as environmental stress responses in plants. Chromatin modifications can also function to prime plants to respond to adverse environmental conditions and act as short-term or long-term (transgenera- tional) stress memory, enabling to be preadapted to the prevailing environment. Recognition of the importance of epigenetic regulation in biological processes is increasing, including its role in salinity stress response, although many details are still lacking. To date, only a few studies in crop plants have provided evidence for epigenetic changes that occur in response to salinity and that result in increasing tolerance to salinity stress. In the current review, we discuss insights into the involve- ment of epigenetic regulatory elements, such as histone modifications, histone vari- ants, regulatory RNAs, and DNA methylation, in salinity stress response based on studies in the model plant, Arabidopsis. In particular, knowledge of the involvement of histone acetylation in salt-stress response has increased, and various chemical compounds capable of regulating levels of histone acetylation have been identified. Based on the available evidence, we provide a perspective on the potential use of chemical epigenetic modifiers, which function as histone deacetylase (HDAC) inhibitors, for enhancing stress tolerance in crops such as cassava.