Hybridization plays a decisive role in the evolution and diversification of angiosperms. However, the mechanisms of wide hybridization remain open because pre- and post- fertilization barriers limit the production and development of inter-subfamily/intergeneric zygotes, respectively. To bypass these barriers, hybridization between wheat and rice using in vitro fertilization (IVF) system was examined in the study. Several gamete combinations of allopolyploid wheat-rice hybrid zygotes were successfully produced, and the developmental profiles of hybrid zygotes were analyzed. Hybrid zygotes derived from one rice egg and one wheat sperm cells ceased at the multicellular embryo-like structure stage. This developmental barrier was overcome by adding one wheat egg cell to the wheat-rice hybrid zygote. In the reciprocal combination, one wheat egg and one rice sperm cells, the resulting hybrid zygotes failed to divide and degenerated. However, doubling the dosage of rice sperm cell allowed the hybrid zygotes to continuously develop into plantlets. Although the regenerated plants derived from wheat-rice hybrid zygotes were successfully obtained, rice chromosomes appeared to be progressively eliminated during early developmental stage of hybrid embryos. The elimination of rice chromosomes gave rise to the hybrid plants displaying wheat plant morphology and approximately 20% of regenerated plants showed abnormal morphology. These results suggest that hybrid breakdown can be overcome through optimization of gamete combinations, and the present hybrid will provide a new horizon for utilization of inter-subfamily genetic resources.