Photorespiration is a cellular conversion process in which plants release carbon dioxide and consume oxygen when exposed to light. Until now, it has been considered an especially wasteful by-product of photosynthesis. Yet according to the latest studies by researchers from Helmholtz Munich, the Technical University of Munich, and Heidelberg University, this process in fact plays an important role in the preservation of the plant epigenome, which controls which genes are turned on or off in response to environmental influences.