Our opportunity is to develop the basis for a new method for hybrid plant production in rice using our proprietary FLP/FRT site-specific recombination system. We have previously demonstrated this system in Arabidopsis (Luo et al. 2000). Our phase I objective is to extend this work to rice and evaluate the efficacy of the FLP site-specific recombinase for excising FRT-flanked male sterility constructs. APPROACH: Transgenic T0 rice plants containing an FRT-flanked expression cassette comprised of either a tapetum-specific promoter driving the cytotoxic gene barnase, or a tapetum cell specific antisense gene, RTS are currently being generated in our lab and are expected to be male sterile. We have generated T0 plants expressing the FLP recombinase in a project funded through a USDA Seed Grant, which we plan to use for testing the restoring function. When male sterile plants containing the FRT-flanked expression cassettes are crossed with plants expressing the recombinase, FLP should excise the sterility gene, restoring fertility and producing a hybrid. If this FLP/FRT system functions at sufficient efficiencies, it will confirm the feasibility that it can be used as a new method for making hybrid plants in crop species. Phase II will implement this system in elite cultivars. NON-TECHNICAL SUMMARY: Based on previous work we anticipate that this project will provide a proof of principle for hybrid rice production as an attractive alternative to the use of CMS in rice. We expect that this technology will become standard to the rice industry and integrated into worldwide breeding programs. We also anticipate that this technology will be used in a wide array of other cereal crop species, which like rice, are not architecturally predisposed to simple mechanical sterilization. It is highly likely that this same system would be extended to other crops of economic importance such as corn, wheat, etc.
Keywords: male sterility; flp/frt; recombinase; hybrid; rice
