BEIJING, July 25 (Xinhua) -- Chinese researchers have achieved a major breakthrough in the cloning of hybrid rice, with the potential to fundamentally transform the conventional paradigm of annual seed production and provide new technological support for global food security.

After years of sustained efforts, a team led by researcher Wang Kejian from the China National Rice Research Institute successfully identified and characterized an endogenous rice gene, which they named "HUAXU." Their study, published in the journal Vita on Tuesday, shows that the HUAXU gene in the egg cells of hybrid rice can efficiently induce parthenogenesis and produce haploid progeny.

When combined with a cloned gamete strategy, multiple apomictic lines developed by the team achieved cloning efficiencies approaching 100 percent. Under various conditions -- including different hybrid rice varieties, across multiple generations, in diverse planting populations, and in large-scale field trials -- the cloning efficiency remained consistently above 99 percent, while yields were maintained at normal levels.

This marks the initial realization of the "from 1 to 100" target for the "one-line hybrid rice" system, representing a critical step toward the vision of "sustained propagation through generations."

Cloning efficiency refers to the percentage of seeds produced through artificially induced apomixis that are genetically identical to the maternal plant. It serves as a key metric for assessing the technical success of fixing heterosis and directly affects seed purity.

Wang said that the currently widely adopted three-line and two-line hybrid rice systems, due to genetic segregation in progeny, cannot preserve hybrid vigor in subsequent generations. As a result, they require annual artificial seed production between male sterile lines and restorer lines.

The core objective of the one-line system is to enable hybrid crops to produce clonal seeds through apomixis, thereby fixing heterosis and enabling "one hybridization, perpetuated through generations." In theory, this means that a single hybrid seed could be sufficient for continuous utilization, eliminating the need for annual reseeding.

Wang noted that the breakthrough addresses a long-recognized global challenge in crop breeding -- permanently fixing heterosis in hybrid rice through seeds. ■