Genetic material contains the intricate blueprints for life, and its transmission represents a fundamental and tightly controlled biological process. In plants, the genetic information is stored in the nucleus and the cytoplasmic organelles: plastids and mitochondria. Both the nuclear and cytoplasmic genomes are essential for plant survival. Intriguingly, the inheritance of these genomes is subject to different sets of rules. While the nuclear genome is a mix inherited from from both parents, in most flowering plants the cytoplasmic genomes are almost exclusively transmitted by the mother1. This non-Mendelian inheritance was identified over a century ago, yet the molecular mechanisms and biological significance of maternal inheritance remains elusive.
In this work, we have established an experimental system allowing the systematic study of plastid inheritance in Nicotiana tabacum. We have identified an environmental factor and a genetic factor that regulate plastid inheritance2. By manipulating the growth temperature and/or genetic background of the paternal plant, we have demonstrated an elevated rate of paternal plastid transmission, shifting the inheritance mode from maternal to biparental2.
In sum, we revealed two independently acting mechanisms that ensure maternal inheritance of the plastids. Our findings reported here can be extended to mitochondrial inheritance, challenging the prevailing notion that mitochondria function as an asexual genetic system.