Epimutations and Metastable Epialleles: Exploring a Mine of Hidden Variation in Crops

For many years, the focus of plant breeders and researchers striving to enhance crop yield, resilience, and quality has revolved around genetic diversity at the DNA sequence level. This approach, rooted in traditional genetics, has yielded invaluable insights and improvements. However, in recent years, we have discovered hidden additional layers of epigenetic diversity, underscoring the importance of understanding variation from a holistic view. Epigenetic diversity comes in the form of epimutations and metastable epialleles that offer a new dimension to explore. These epigenetic modifications can exert a significant effect on gene expression and the resulting phenotypes, making them targetable for crop improvement. Even more important is the fact that epigenetic marks are generally not static, which means they can be reversibly influenced by environmental factors, stressors, and developmental cues. Epialleles can be meiotically heritable, passing from one generation to the next through the germline, and even revert to their original state over a few generations. This dynamic nature becomes vital for crops to thrive under fluctuating environmental conditions.