Technology "One Step in Place" Hybrid Wheat Breeding Industrialization Makes Another Success

　　◎Our reporter Ma Aiping

　　Planting hybrid wheat is considered to be one of the preferred ways to substantially increase global wheat production in the future.

It is predicted that if the popularization and application of hybrid wheat reaches the same level as hybrid rice, my country can increase its annual wheat output by about 12 million tons (calculated based on China’s total annual wheat output of 120 million tons and a 10% increase in output), which will have a significant impact on ensuring national food security. Significantly.

However, wheat, which is also one of the three major food crops in the world, is limited by the complexity of its genome (heterohexaploid), and its hybrid breeding has been stagnant for a long time.

At the same time, the high cost of seed production also greatly restricts the industrialization of hybrid wheat.

　　The team of Lu Jian, a senior researcher at the Beijing Innovation Center of Syngenta Group, told the Science and Technology Daily reporter on January 11 that they cooperated with the team of Syngenta Seed Industry Scientist Tim Kelliher. Technology" published a research result: the team developed the first commercially available paternal haploid induction technology, which can greatly reduce three-line wheat (cytoplasmic male sterile line, male sterile maintainer line and male sterile line). Sterile restorer line) hybrid seed production cost.

　　The male parent haploid of Arabidopsis is induced to replicate on wheat

　　Three-line wheat hybrid seed production technology is widely used in hybrid wheat production.

When using three-line wheat hybrid seed production technology, it is necessary to convert materials that are not sterile lines into a cytoplasmic male sterile background. The essence is to replace the nucleus of the original male sterile material with the nucleus of the new material while maintaining the original Male sterile cytoplasm of sterile line materials.

But this operation keeps the cost of three-line wheat hybrid seed production high.

　　"This is very easy to achieve on animal cells. The nucleus of the original cell can be removed by micromanipulation, or the original nucleus can be destroyed by chemical treatment, and then the new nucleus can be transplanted into the original cytoplasm." Lu Jian explained, However, this method cannot be implemented on crops because the micromanipulation needs to destroy the cell wall of plant cells, and it is difficult to regenerate a complete plant from plant cells with cell walls removed.

　　The traditional method is to cross the cytoplasmic fertile variety (B material) with the existing cytoplasmic sterile line (A material) and backcross for 5-7 generations to ensure that most of the nucleus of the final material is from B The genome of the material.

Obviously, this method is time-consuming and a waste of resources.

　　Moreover, the final material obtained by the above-mentioned traditional methods is not 100% identical in genome to the original B material.

　　For this reason, Lu Jian’s team developed a one-step cytoplasmic sterile line transfer technology.

This is based on the paternal haploid technology, the sterile line is developed into the paternal haploid induction line, the material to be transformed is induced to the paternal haploid, and then the haploid doubling technology is used to achieve cytoplasmic sterility One step transfer.

　　However, there are few genes that can be used for paternal haploid induction, and the Arabidopsis CENH3 gene is recognized as a key gene for breakthroughs in paternal haploid induction technology.

However, many scientists have spent tremendous efforts trying to replicate the success of Arabidopsis CENH3 gene paternal haploid induction technology in other crops, and they all ended in failure, so that the scientific community once suspected the paternal haploid induction of CENH3 gene. Is it only possible on Arabidopsis?

　　Lu Jian firmly believes that the male parent haploid induction of CENH3 can be achieved in hybrid wheat.

He and the co-corresponding author of the paper, Kelleher, innovatively designed a pair of gRNAs, only introducing back-code mutations at the N-terminal of the CENH3 gene, without changing the carboxyl segment and promoter region, and finally achieved a 7% paternal single Ploidy induction rate.

　　Shorten the breeding time of hybrid wheat from 3 years to one year

　　Using this technology can shorten the original 3 years (7 generations) for hybrid wheat seed production to less than a year (2 generations).

Therefore, this technology is also known as the "one-step" technology for hybrid wheat seed production.

　　“It is very time-consuming and labor-intensive to select and match wheat sterile line materials. The traditional method requires many years of cross-breeding.

　　This kind of cost is very high.

This breeding technology accelerates the germplasm improvement and reduces the cost of seed production. It can quickly realize the creation of sterile lines, greatly accelerate the process of hybrid wheat variety selection, faster and easier, and can promote hybrid wheat in a wider range Utilize and promote.

"Lu Jian said.

　　Surprisingly, the researchers achieved a 7% paternal haploid induction rate, which is the first time in the world to achieve such a large rate of paternal haploid induction on real crops.

Previously, another gene that can be used for paternal haploid induction is ig1 in maize, but it can only produce 1% haploid induction rate in maize; the same gene has been confirmed to be unable to induce haplotype in wheat. body.

　　"The induction rate of 7% can be said to be a very good start. It is the first time that it has been successfully achieved in wheat. This efficiency is commercially feasible." said Zhang Bei, president of Syngenta Beijing Innovation Center. Line transfer technology can accelerate the basic research of wheat heterosis and the promotion of hybrid wheat.

　　This technology also paves the way for the application of CENH3-based haploid gene editing coupling technology (HI-EDIT) in a variety of crops.

The same method and design pattern may be extended to other crops that do not have a haploid induction system.

"We are exploring on soybeans and tomatoes." Lu Jian revealed.