As global demand for plant protein and edible oil surges, increasing soybean yield has become a top priority in agricultural science. While heterosis utilization is a key pathway for yield improvement, traditional "three-line" hybrid systems face significant bottlenecks, including limited genetic resources and low seed production efficiency. A new study from China offers a promising solution by targeting nuclear male sterility genes. The research team, led by Professor Meina Li from Guangzhou University and Professor Chunbao Zhang from the Jilin Academy of Agricultural Sciences, have successfully created completely male sterile soybean lines by knocking out GmDYT1a and GmDYT1c , paving the way for more efficient third-generation hybrid breeding.
The researchers identified a unique "two-gene" regulatory mechanism involving GmDYT1 . Using CRISPR/Cas9 gene editing, they precisely knocked out two functionally redundant genes, GmDYT1a and GmDYT1c , to create stable male sterile lines.
Hybrid soybeans have shown significant yield advantages, with some varieties exceeding conventional checks by over 20%. However, the widespread commercialization of these crops has been hindered by the limitations of current breeding methods. Third-generation hybrid breeding technology, centered on nuclear male sterility genes, has proven successful in rice and maize and offers a new direction for soybeans. The key to scaling this technology lies in identifying genes that not only confer sterility but also maintain high outcrossing rates for efficient seed production.
Previous work by the team had characterized other male sterility genes like MS1 ( GmNACK2a ), MS2 ( GmAMS1 ), and MS6 ( GmTDF1 ). Noting that ms2 and ms6 mutants had superior outcrossing rates, the researchers hypothesized that targeting the upstream DYT1 gene in the conserved DYT1-TDF1-AMS regulatory pathway could yield similar benefits. Through genomic analysis, they identified three homologs: GmDYT1a , GmDYT1b , and GmDYT1c . GmDYT1b proved non-functional in fertility regulation, whereas GmDYT1a and GmDYT1c showed marked functional divergence.
The current study revealed that single knockouts of either GmDYT1a or GmDYT1c did not affect fertility. Only the simultaneous knockout of both genes resulted in complete male sterility. This confirms a core characteristic of functional redundancy between the two genes. Further experiments showed that while GmDYT1a localizes to the cytoplasm and GmDYT1c to the nucleus, both are required to activate the downstream fertility gene GmTDF1 .
Crucially for breeders, the gmdyt1a gmdyt1c double mutant exhibited an outcrossing rate comparable to the high-performing ms6 mutant and significantly higher than ms1 . This suggests excellent potential for large-scale seed production.
“Based on these findings, we propose an innovative "two-gene" regulation strategy for hybrid soybean breeding,” says Li. “In this system, the restorer line carries functional copies of both genes, ensuring stable fertility restoration in the F 1 generation. This approach significantly reduces the risk of restoration failure caused by natural variations, addressing a major pain point in current hybrid systems.”
"The gmdyt1a gmdyt1c– based system holds great potential for yielding hybrid seeds with strong fertility restoration and a high outcrossing rate, which are critical for the commercial application of third-generation hybrid breeding technologies in soybean adds Zhang.
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Contact the author:
Name: Xiaolong Fang
Email address: fangxiaolong1215@163.com
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The Crop Journal
Experimental study
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Knockout of functionally redundant GmDYT1 genes confers complete male sterility in soybean