Origin of Epigenetic Variation in Plants: Relationship with Genetic Variation and Potential Contribution to Plant Memory

Plants are sessile organisms that must cope with various environmental cues. Mechanisms allowing learning and memory are, therefore, essential for the plant life cycle. Various studies suggest that epigenetic-related mechanisms could play a key role in plant learning and memory. The importance of epigenetics in these processes mainly relies on its correlation with environment and the possibility to more easily revert the resulting phenotypic changes compared to those associated with the direct DNA sequence alteration. Nevertheless, an obvious cross talk between genetic and epigenetic variation occurs. This review discusses about the nature and origin of epigenetic variation, thus allowing to better understand the contribution of epigenetic variation to plant memory.