Passing down a healthy genome is a critical part of creating viable offspring. But what happens when you have harmful modifications in your genome that you don't want to pass down? Baby plants have evolved a method to wipe the slate clean and reinstall only the modifications that they need to grow and develop. Cold Spring Harbor Laboratory (CSHL) Professor & HHMI Investigator Rob Martienssen (photo), PhD, and his collaborators, Jean-Sébastien Parent, PhD, and Institut de Recherche pour le Développement Université de Montpellier scientist Daniel Grimanelli, PhD, discovered one of the genes responsible for reinstalling modifications in a baby plant's genome. A plant's genomic modifications--called epigenetic modifications--help turn off genes at the right times. Epigenetic changes accumulate with age. Martienssen explains. "If you think about a tree, the flowers that arise a hundred years after it germinated, they're obviously a long way from the original acorn, and an awful lot of epigenetic changes could happen in that period. And so, these are important resets for development so that you don't inherit this epigenetic collateral damage." Dr. Martienssen's team discovered that after baby plants remove the epigenetic modifications, the SUVH9 protein puts back the ones they need to survive. Without SUVH9, plants develop poorly because the wrong genes turn on at the wrong time.