To meet the world food needs in the future, it is necessary to increase the grain production of world major crops. I have studied about the improvement of rice using closely related rice species. Especially, I have been using African rice species that is not well known in Japan. During the research, I have found that hybrids between African and Asian rice species show vigorous growth. However, these inter-specific hybrids do not produce seeds, and, therefore, we cannot use the inter-specific hybrids for food production. Both the vigorous growth and seed sterility seen in inter-specific hybrids are thought to be due to an interaction between genomes from the two species. In the present project, I will try to understand the effect of such genomic interactions on the performance of inter-specific hybrids using recently progressed omics and genome editing technologies.