Researchers have developed a new method for creating male sterility in rapeseed using CRISPR/Cas9 technology, increasing the production of hybrid seeds.

Heterosis, also known as hybrid vigor, is a phenomenon where the offspring obtained by crossing two inbred lines surpasses the productivity of the parental lines. In agricultural crops, especially in inbred species, heterosis can significantly increase yield by 20–50%.

Rapeseed is an oilseed crop grown for vegetable oil production and is an important agricultural crop plant. Hybrids have played a key role in increasing the productivity and overall production of rapeseed, especially in major production regions such as Canada, China, and Europe. The main approach to hybrid development in rapeseed is based on using male sterility, which allows the exploitation of the benefits of heterosis.

Male sterility is an anomaly in the development of anthers in higher plants during sexual reproduction. Its existence has been discovered in tobacco and other plants such as rice, maize, rapeseed, and soybeans.

Male sterility can be cytoplasmic (CMS) or genetic (GMS). CMS, usually controlled by mitochondrial genes and some nuclear genes, is used for producing hybrid seeds with a three-line system. CMS eliminates the need for anther removal and simplifies the process of hybrid seed production.

However, in rapeseed, there are some limitations and issues with the existing cytoplasmic male sterility systems. Some systems, like Pol, are unstable due to external factors, while the Ogu system struggles to find suitable restorers. Limited genetic diversity and increased susceptibility to diseases also restrict the application of cytoplasmic male sterility systems.

As a result, rapeseed breeding faces serious challenges due to the complexity and limitations of existing male sterility systems. Traditional methods require complicated processes and are sensitive to environmental conditions, leading to unstable and inefficient hybrid seed production.

Researchers from Zhejiang University and Jiangsu Academy of Agricultural Sciences have developed a new approach using CRISPR/Cas9 technology. They targeted the BnDAD1 gene, which plays a role in jasmonic acid biosynthesis, to induce male sterility in rapeseed, simplifying hybrid seed production. The research results have been published in the journal Horticulture Research.

The researchers successfully disrupted the BnDAD1 gene, which is expressed in the stamens of rapeseed flower buds, using CRISPR/Cas9 technology. This disruption resulted in male sterility due to defects in anther dehiscence and pollen maturation in rapeseed.

By using exogenous methyl jasmonate, researchers were able to restore fertility in male-sterile lines, allowing the production of F1 hybrid seeds.

The researchers stated: "We propose a novel method involving the disruption of the crucial gene BnDAD1 in the jasmonic acid biosynthesis pathway using CRISPR/Cas9 technology to induce male sterility in rapeseed. Disruption of BnDAD1 leads to reduced levels of α-linolenic acid and jasmonate in double mutant lines, resulting in defects in anther dehiscence and pollen maturation."

"By crossing male-sterile lines with male-fertile lines, we demonstrated the potential for F1 seed production using a two-line system. This breakthrough holds significant commercial potential and promises to improve the efficiency and resilience of rapeseed production. Our results represent a significant advancement in hybrid rapeseed production. The use of CRISPR/Cas9 to induce male sterility simplifies the selection process and opens up broad possibilities for increasing rapeseed yield and resilience," noted Dr. Lisi Jian, a lead researcher from Zhejiang University.

This new two-line system offers a simpler and more efficient method for hybrid seed production compared to traditional methods.

"Male sterility achieved through CRISPR/Cas9 is stable and complete, regardless of environmental conditions, making it a reliable solution for hybrid rapeseed production. This innovative approach has great commercial potential and promises to increase the efficiency and resilience of rapeseed production. Our results are a significant step in hybrid rapeseed production. Using CRISPR/Cas9 to induce male sterility simplifies the selection process and opens up possibilities for increasing rapeseed yield and resilience," emphasized Dr. Lisi Jian.