Scientists at the Max Planck Institute of Molecular Plant Physiology in Potsdam (Germany) analyzed for the first time the inheritance of chloroplasts under a wide range of environmental conditions. Contrary to the prevailing view that chloroplasts are only passed on by the mother plant, paternal chloroplasts can also be transmitted to the offspring under cold conditions. Maternal and paternal chloroplasts thus meet in the offspring and may be able to exchange genetic material with each other. The new findings may allow plant breeders for the first time to selectively use traits from the genetic material of chloroplasts.