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Self-perpetuating hybrid rice

Jiangdi Li , Xuehui Huang

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Vita > Cutting Edge > DOI: 10.15302/vita.2026.07.0051
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Self-perpetuating hybrid rice

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In a recent study published in Vita, Chen et al. identify a sperm-specific transcription factor-coding gene HUAXU/OsRKD8 and express it in egg cells under a fine-tuned attenuated promoter. This approach enables synthetic apomixis in hybrid rice, achieving > 99% clonal seed production while maintaining normal seed set.

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Heterosis, or hybrid vigor, refers to the superior performance of hybrids — offspring produced by crossing genetically divergent parents — in terms of growth rate, biomass, grain yield, and adaptability1. This phenomenon has been extensively applied in major food crops and horticultural species, including rice, maize, foxtail millet, rapeseed, and tomato, significantly boosting global agricultural productivity. Today, most commercialized plant varieties are hybrids. However, due to trait segregation in progeny and consequent loss of superior traits in subsequent generations, hybrid seeds must be regenerated each season. This process entails considerable technical challenges and high production risks, which collectively escalate the cost of hybrid seed production and substantially hinder the broader adoption of hybrid varieties.
Rice, the staple food for more than half of the world's population, serves not only as a major dietary component in Asia but also as a well-established model plant for basic research and heterosis breeding2. As a naturally self-pollinating species, rice requires elaborate male sterility systems — cytoplasmic male sterility for three-line hybrids, and photoperiod/thermo-sensitive genic male sterility for two-line systems. The male sterility systems were developed several decades ago, and have enabled large-scale hybrid seed production. Furthermore, the identification of heterosis-associated genes and the development of genomic breeding systems have facilitated parental line improvement, guided cross designs and accelerated hybrid breeding3,4. Many hybrid varieties with elite genotypic combinations have been developed and widely used in agricultural production.
Alongside the advances in male sterility and heterosis studies, to circumvent the high cost and labor-intensive nature of annual hybrid seed production, a promising strategy is to propagate hybrid rice clonally via seeds — a method that enables elite genotypes to be transmitted across generations without recurrent seed production5. Many wild plants naturally produce clonal seeds through a process called apomixis — asexual reproduction via seeds that fixes hybrid vigor by preventing segregation. Professor Longping Yuan, who pioneered the three-line and two-line hybrid rice systems and is hailed as the father of hybrid rice, proposed apomixis as one-line breeding strategy to fix heterosis6. In two landmark studies, Venkatesan Sundaresan and colleagues discovered that the rice gene Baby Boom 1 (BBM1), when ectopically expressed in egg cells, could induce parthenogenesis. Combined with the Mitosis instead of Meiosis (MiMe) system, they successfully obtained clonal seeds of rice7. Meanwhile, the team led by Kejian Wang at China National Rice Research Institute used multiplex genome editing to simultaneously disrupt four reproduction-related endogenous genes, successfully engineering synthetic apomixis in hybrid rice8. However, early systems suffered from either low clonal efficiency or significant seed set penalties, preventing their wide applications in agriculture production.
The present study by Kejian Wang and his colleagues takes this technology to an entirely new level9 (Fig. 1). Through integrated transcriptomic analyses, the team identified a sperm-specific transcription factor-coding gene, HUAXU/OsRKD8, which likely functions as a key initiator of embryogenesis. When ectopically expressed in egg cells under a newly identified promoter, HUAXU induces parthenogenesis with remarkable efficiency. Combined with the MiMe system for clonal gametogenesis, this approach achieves synthetic apomixis with clonal seed production rates of nearly 100% across all tested hybrid rice cultivars, independent transgenic lines, and successive generations. Critically, by fine-tuning HUAXU expression with the weaker EGG2 promoter, the team restored seed set to levels statistically indistinguishable from conventional F1 hybrids, breaking the long-standing trade-off between clonal efficiency and fertility. This system has met commonly-used seed purity standards, demonstrating genuine agricultural viability.
Unlike earlier synthetic apomixis systems that relied on strong egg-cell promoters — often causing a pronounced trade-off between clonal efficiency and fertility — this study introduces a conceptually elegant regulatory refinement. By systematically mining the egg-cell transcriptome, the authors identified a set of attenuated promoters and selected the EGG2 promoter to drive HUAXU expression. This simple but powerful substitution attenuates ectopic transgene activity just enough to retain full parthenogenetic potency while eliminating the pleiotropic fertility penalty. The resulting lines achieved > 99% clonal efficiency across hundreds of progeny, yet their seed-setting rates were generally normal — a feat not accomplished in previous systems, where highly clonal lines mostly suffered yield reductions. This promoter-tuning strategy demonstrates that the key to engineering practically deployable apomixis lies not solely in discovering potent inducers, but also in achieving precise spatiotemporal control over their expression10.
Looking ahead, the synthetic apomixis strategy holds immense promise for extension to other hybrid crops such as maize, where heterosis is equally pivotal. The sperm-specific expression pattern of HUAXU orthologs across species suggests potential broad applicability. Nevertheless, it remains not clear whether the system can perform robustly under diverse eco-agronomic environments, e.g., high-temperature stress during flowering and grain filling — an increasingly critical concern in the era of climate change11. Multi-environment and multi-genetic background field trials and comprehensive evaluations on cultivation and management will be essential before large-scale commercial deployments. Yet, with this study, the dream of self-perpetuating hybrid crops has moved from proof-of-concept to the brink of reality.

[1]

Liu, J., Li, M.J., Zhang, Q., Wei, X. & Huang, X.H. J. Integr. Plant Biol. 62, 287–298 (2020).

[2]

Huang, X.H. et al. Nature 537, 629–633 (2016).

[3]

Wei, X. et al. Nat. Genet. 53, 243–253 (2021).

[4]

Fang, Y. et al. Plant Biotechnol. J. 24, 523–525 (2026).

[5]

Marimuthu, M.P.A. et al. Science 331, 876 (2011).

[6]

Wang, K.J. Nat. Plants 7, 858–859 (2021).

[7]

Khanday, I., Skinner, D., Yang, B., Mercier, R. & Sundaresan, V. Nature 565, 91–95 (2019).

[8]

Wang, C. et al. Nat. Biotechnol. 37, 283–286 (2019).

[9]

Chen, W. et al. Vita https://doi.org/10.15302/vita.2026.07.0053 (2026).

[10]

Song, X.G. et al. Nat. Biotechnol. 40, 1403–1411 (2022).

[11]

Zhao, C. et al. Proc. Natl. Acad. Sci. USA 114, 9326–9331 (2017).

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The Author(s) 2026. Published by Higher Education Press. This is an Open Access article distributed under the terms of the CC BY license (https://creativecommons.org/licenses/by/4.0/).

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Li, J., Huang, X.  Self-perpetuating hybrid rice  Vita https://doi.org/10.15302/vita.2026.07.0051 ()
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