Epimutations Define a Fast-Ticking Molecular Clock in Plants
The discovery that epimutations spontaneous,heritable changes in DNA methylation act as a fast-ticking molecular clock in plants represents a profound shift in our understanding of evolutionary timescales and inheritance. This "epimutation-clock" provides an unprecedented tool for studying evolutionary divergence over remarkably short periods, a scale largely inaccessible to traditional genetic methods. The core finding is that stochastic changes in DNA methylation at certain cytosine sites, particularly in CG dinucleotides, accumulate at a rate orders of magnitude faster than genetic mutations, yet remain sufficiently stable and neutral to serve as a reliable temporal marker. How Epigenetics Affects the Molecular Clock Epigenetics refers to heritable changes in gene function that occur without a change in the DNA sequence itself. The key epigenetic mechanism in the plant clock is DNA methylation, the addition of a methyl group to a cytosine base. Specifically, th...