China’s new hybrid rice can be passed down through generations, retaining its high-yielding characteristics, potentially allowing farmers to replant seeds without having to buy new seeds every year
China’s new hybrid rice can be passed down from generation to generation, maintaining its high-yielding characteristics, allowing farmers to replant seeds without having to buy new seeds every year.Scientists at the China Rice Research Institute in Hangzhou have developed a self-cloning hybrid rice system that maintains excellent crop yields while achieving cloning efficiency of over 99%. The study, led by researcher Wang Kejian, was published in the academic journal “Vita” on July 21, with more details reported by the Global Times.This breakthrough targets a long-standing obstacle in modern agriculture, hybrid vigor. The yield of hybrid rice is 10 to 30% higher than that of standard varieties. However, when farmers harvest and replant seeds from traditional two- or three-line hybrid crops, the genetic traits segregate in the next generation, causing the yield advantage to disappear.
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As a result, growers are forced to buy fresh hybrid seeds every season.
How Huaxu Gene Unlocks Seed Cloning
Wang’s research team began tackling this problem in 2013, focusing on synthetic apomixis, a natural plant process in which seeds are formed without fertilization, creating an exact genetic copy of the parent plant.The breakthrough relies on an endogenous rice gene called “HUAXU.” When expressed in hybrid rice egg cells, HUAXU triggers parthenogenesis, causing the egg cells to grow into embryos without male fertilization. By combining this mechanism with a cloning gamete strategy, the team created an improved rice line called Fix8.Unlike earlier gene editing methods that required the introduction of foreign genes, HUAXU is a naturally occurring gene in rice. This distinction simplifies regulatory review and commercial deployment.In large-scale field trials with different rice varieties, multiple generations and different weather conditions, the Fix8 line maintained cloning efficiency of more than 99% while maintaining normal fertility and crop yields. In theory, having access to a single hybrid seed would allow farmers to continuously grow high-yielding rice without having to purchase new stock every year.Early experiments conducted by the team in 2017 achieved only 5% cloning efficiency, while rival research groups later achieved approximately 95% cloning efficiency using complex genetic mutations. Reaching the 99% standard meets the threshold required for commercial application and achieves a long-sought goal in the field of plant breeding, often referred to as the “monoline hybrid rice” concept.
Chinese scientists have made a major breakthrough in hybrid rice breeding and developed “clonal hybrid rice” (Photo: provided by Wang Kejian)
Seed cost cuts to aid global farms
High production costs have historically limited the promotion of hybrid crops. Currently, hybrid rice accounts for about 50% of China’s rice fields, but only 5% of the global rice planting area.Producing hybrid seeds through conventional cross-breeding is labor-intensive and costs 10 to 20 times more than conventional seeds, even without processing, storage and transportation costs.“The cost of producing hybrid seeds is 10 to 20 times that of traditional seeds, which makes high-yield hybrid rice unaffordable for many developing regions, especially African countries that need higher yields the most,” Wang told the Global Times.New cloning technology significantly reduces these costs. According to data provided by Wang’s team, the seed price of the Fix8 strain may drop to between 2 and 5 yuan per half kilogram. Currently, standard hybrid seeds in China are sold for 20 to 100 yuan per kilogram.Expanding the global hybrid rice cultivation area from 5% to 25% will significantly increase the world’s food supply. Eliminating the need for annual seed production also gives plant breeders greater freedom to introduce genetic diversity to help crops withstand climate stress, disease and extreme weather.
Support national and global food security
This development has significant implications for Chinese agricultural policy and global grain markets. China uses less than 9% of the world’s arable land to feed nearly one-fifth of the world’s population, and hybrid rice is the main driver of agricultural output.Official statistics show that China’s total grain output has stabilized at more than 700 billion kilograms for two consecutive years. This figure is much higher than the internationally recognized safe baseline of 400 kilograms per capita.By eliminating the need to produce hybrid seeds every year, the new monoline system provides a permanent way to lock in high yields, reducing production costs for farmers while enhancing long-term food self-sufficiency.
Advances in seed propagation technology
Traditional hybrid rice cultivation relies heavily on multi-line breeding systems, mainly three-line and two-line methods. These techniques require specialized cross-breeding between male-sterile and restorer lines to produce viable hybrid seeds. Since this labor-intensive process must be repeated each season, seed purity and quality control remain ongoing challenges for commercial producers.The development of synthetic apomixis using HUAXU genes has fundamentally changed this dynamic. By inducing parthenogenesis directly within unfertilized egg cells, plants produce haploid offspring that carry exactly the same genetic material as the parent plant.Clonal efficiency is the primary benchmark for measuring how reliably a crop maintains its hybrid vigor. While early efforts struggled to maintain high success rates without compromising overall plant fertility, crossing the 99% threshold in field trials confirmed that cloned seeds can be propagated for multiple generations without loss of productivity or crop resilience.
