Tety Maryenti (currently an assistant professor at the University of Indonesia) of the Graduate School of Tokyo Metropolitan University, together with researchers from Tottori University and the National Institute of Genetics, conducted genome analysis of a wheat and rice hybrid plant (rice wheat) (announced in October 2021) created in previous research, and revealed that rice wheat is a cytoplasmic hybrid wheat that contains rice mitochondria.
Wheat, rice, and corn account for approximately 9% of the world's grain production. Although they are all grasses, they belong to different subfamilies, making it extremely difficult to crossbreed them and preventing them from utilizing each other's excellent genetic resources.
In this study, gametes (egg cells and sperm cells) isolated from wheat and rice flowers were fused in any combination using in vitro fertilization to produce a rice-wheat hybrid plant, Oryzawheat, and the genome sequences and compositions of the plants were determined.
As a result, it was found that rice-wheat is a cybrid wheat that has the wheat genome as its nuclear genome and the rice genome in addition to the wheat genome as its mitochondrial genome. In addition, in one individual whose genome was analyzed, it was confirmed that the rice-wheat had a portion of the rice nuclear genome remaining within the wheat nuclear genome. However, because this rice-wheat was a "chimera" in which cells with different genetic information were mixed in the same individual, the transmission of the rice genome to the next generation could not be confirmed.
Mitochondria function as sensors to detect environmental changes and stress, such as dryness, low temperatures, and pathogen infection. As it is highly likely that rice-wheat has acquired novel characteristics not found in wheat, evaluation of these characteristics is currently underway. This is the first time in the world that rice genetic resources have been introduced into wheat. It is said that the method of producing hybrid plants using ICSI is expected to become a new breeding technique.
