Epigenetic adaptation to drought and salinity in crop plants

The severe impact of drought and salinity on plant productivity presents a significant threat to worldwide food security. Plants exhibit the capacity to sense stimuli in their environment and adjust defense mechanisms through diverse regulatory networks to cope with abiotic stress. The complexities of drought and salinity tolerances can be deconstructed into contributing factors and mechanisms, classified under two categories: genetics and epigenetics. Epigenetic mechanisms play a role in partially attributing crop adaptation to the most formidable drought and salinity stresses. Plants respond to stress in part by undergoing stable alterations in gene expression, a process that involves the physical "marking" of DNA or its associated proteins, commonly called epigenetics. Plants utilize various epigenetic mechanisms to refine gene expression, vital for adaptation and phenotypic plasticity. These include DNA methylation, histone modifications, chromatin remodeling, epitranscriptomics, and gene silencing mediated by small RNAs. Notably, epigenetic modifications can be inherited or erased. Enhanced knowledge of epigenetics complements genetics and will aid in developing strategies to integrate them into crop improvement programs aimed at addressing adaptation to abiotic stress. This review highlights the latest and noteworthy findings regarding crop epigenetic responses to abiotic stress signals, particularly those pertinent to drought and salinity tolerance.