As the chloroplasts of plants are maternally inherited, the transgenes are not spread by pollen thus achieving biological containment. In other words, the cell nucleus contains no transgenes, and the pollen contains no chloroplasts and thus no transgenes.[1] Two important research projects on co-existence are and Co-Extra. With the end of the de facto moratorium on genetically modified plants in Europe, several research programmes (e.g. SIGMEA, Co-Extra, and Transcontainer) have begun investigating biological containment strategies for GMOs.