Apomixis technology and the paradox of sex

Most plant species produce genetically variable seeds by the fusion of meio tically reduced egg cells and pollen grains. However, a small proportion of seed plants produces clonal, asexual seeds by the process of apomixis. The fixation of heterosis by apomixis is of great interest for plant breeding. The prospect of changing sexual crop species into apomictic crop species-b y genetic engineering - apomixis technology - has recently caused a boom in apomixis research. According to evolutionary biological theories, a domina nt apomixis gene will rapidly become fixed in an outcrossing sexual populat ion. Therefore, in theory, apomixis transgenes could have unconditional adv antages that could result in the uncontrollable spread of the transgenes. B y contrast, 'classic' transgenes might only have conditional advantages. Pa radoxically, sexual reproduction and not apomixis is common in nature. Howe ver, this is no guarantee that apomixis transgenes will be ecologically saf e because there could be essential differences between natural and transgen ic apomicts.