Engineering synthetic apomixis in different hybrid rice varieties using the Fix strategy

Hybrid rice breeding has significantly increased the yield and stability of rice production. However, due to trait segregation in F2 progeny seeds, the F1 hybrid seeds must be renewed annually. Apomixis is a form of reproduction leading to clonal seeds, which has a revolutionary potential in fixing heterosis and realizing selfretention of hybrid rice seeds. Previously, we successfully engineered synthetic apomixis in rice by combining Mitosis instead of Meiosis (MiMe) with haploid induction (mutation of MATRILINEAL), a strategy known as Fix for Fixation of hybrids. However, only one hybrid rice variety has been tested for the Fix synthetic apomixis system. In this study, we expanded the application of the Fix strategy and achieved synthetic apomixis in multiple hybrid rice varieties. We observed significant variations in seed setting rate across diverse genetic backgrounds and witnessed a remarkable tenfold increase in clonal seed efficiency. Our findings will provide valuable insights into the application of the Fix strategy for synthetic apomixis in hybrid rice.