A Critical Guide for Studies on Epigenetic Inheritance in Plants.

Studies on "epigenetic inheritance" or "transgenerational epigenetic inheritance" have emerged at ever-increasing numbers in the last years, in plant as well as animal systems and in diverse contexts ranging from stress adaptation to behavioral studies. Despite the very different organisms and biological processes investigated, the overarching question has been if and how an organism's epigenome registers and records external cues and relays this information to its progeny. Very often, these experiments are based on the hypothesis that epigenetic memorization of events or conditions could be the basis of an altered response of the progeny upon encountering the same or a similar condition. If confirming the hypothesis, such studies challenge our fundamental understanding of evolution by natural selection; therefore they require particular rigor in design and great care in data analysis. Here, we want to provide general guidelines on how to design studies on epigenetic inheritance in plants and to consider critical points during data analysis and interpretation. While we cannot provide a step-by-step guide that fits all experimental setups and questions addressed, we explain frequent misconceptions and often overlooked pitfalls. Our aim is to provide researchers with conceptual tools to sensibly design their studies and to interpret their results in the admissible framework.