What is the secret of space breeding?

At dawn on November 1, the Shenzhou 8 spacecraft that performed the first space rendezvous and docking mission in China successfully took off. The match of "God 8" is the first space breeding platform in China - Tiangong 1.

Space breeding, also known as space mutation breeding and space breeding, refers to the use of return spacecraft and ground-simulating space environment devices to induce mutagenic effects on plants through space environment, resulting in variation of seeds, and then through a strict ground breeding process. Get excellent crop varieties.

Crop seeds, as one of mystery visitors to explore space in China, all appeared in the missions of the previous Shenzhou series of spacecraft. In the situation where traditional genetic resources for breeding are still insufficient and breeding methods are relatively single, aerospace breeding has become an important strategic choice for ensuring national food security. What is the mutagenic mechanism of space breeding? Why can't the ground simulation be replaced? What aspects of modern molecular biology can't reach? So far, scientists have not fully understood the mechanism of space mutagenesis.

After the “God 8” launches, it will be equipped with a mutagenesis device to dock Tiangong 1, verifying the conjectures of scientists.

Space Mutagenesis Several heavy poplar tree species have been mutagenized and returned to the ground to develop excellent salt-alkali resistance. As a result, scientists suspected that the mutagenesis mechanism may be caused by the influence of the space environment on the cell membrane protein channels of the tree species so that they no longer absorb sodium ions.

This is a typical example of space-induced breeding - "accidentally" to obtain a desired trait, does not rule out the appearance of the opposite trait. However, what puzzles scientists is that, regardless of the outcome is good or bad, this mutagenesis mechanism is still full of mystery.

In the past, crop seeds that were lifted off through spacecraft were cultivated on the ground and showed different traits: some became larger, some became smaller, and some even changed to “zero”.

According to Dr. Pang Xin, a space breeding expert at the China Academy of Space Technology, "the mutation rate is generally a few percent or even several thousandths, and the beneficial genetic variation is only about three-thousandths."

In the space mutagenesis mechanism research, Chinese scientists have conducted a lot of research work. Some experts believe that the space environment can cause changes in the bases of biological genomic DNA, resulting in DNA fragmentation and reorganization, and thus induce mutations.

At the 2011 “Aerospace Engineering Breeding Forum” held recently, Liu Min, the chief Chinese scientist of the Chinese-Russian space program, emphasized that the cause of seed mutagenesis may be related to the transposon in the plant genome. Transposons are a type of mobile genetic factor.

"What factors in the space environment can activate transposons and which parts of transposons are easily activated? These issues have yet to be explored," Liu Min said in an interview.

Although there are many unsolved mysteries in space mutation, its unique advantages in breeding cannot be replaced. Space-borne experiments have shown that the mutation rate of the seed gene is 5 times higher than that of the ground. This also means that the ground simulation can only meet part of the space mutagenesis conditions.

"The near-neighbor space area with a height of less than 500 kilometers is an important activity area for space breeding." Yu Futong, director of the Plant Nutrition Department of the College of Resources and Environment, China Agricultural University, told reporters.

Cai Zhenbo, a researcher at the China Academy of Space Technology, pointed out at the aforementioned meeting that there are environmental elements in this region that are quite different from the Earth's environment. Among them, vacuum, Earth's magnetic field, particle radiation, and microgravity are key space environments that can be used in space breeding. Resources.

Space Breeding "Trilogy"

It is different from the return satellites and spacecrafts. Because of the ever-changing space environment, every space travel has "randomness", which limits the repetition of experiments.

This time, “God Eight” and “Heaven” will meet and establish a space laboratory, which will provide a long-term space environment and a stable experimental platform for China’s space breeding, so as to obtain accurate spatial mutagenesis data.

In the "roadmap" for space breeding described by Liu Xiangxiang, chief expert of the National Space Breeding Project, space breeding is divided into the "trilogy" of carrying, entering the palace, and hanging outside.

“Whether in the cabin or in the seeds of a space experiment station, many particles of the universe have been shielded, but it is expected that in the near future, it would be a reality to hunt the seeds outside the space station and fully accept the cosmic rays. "Liu Luxiang said.

So far, China has successively used 15 return satellites and 7 Shenzhou spacecrafts, equipped with thousands of crop seeds, test-tube seedlings, biological strains and materials, and obtained a large number of varieties with new traits.

At present, China has a total of 393 strains of 9 major categories of crops that have been carried by space, and more than 70 new varieties have been bred and passed national or provincial accreditation.

Sufficient conditions for future development Our country is the third country in the world following the Soviet Union and the United States to master satellite recycling technology. The success rate of satellite recycling has reached the international advanced level, which lays the foundation for China's aerospace engineering breeding.

Academician of the Chinese Academy of Engineering, China Academy of Space Technology Technical Consultant and chief designer of the Shenzhou-5 manned spaceship Qi Fazhao said in an interview with reporters recently that with the gradual completion of China's space station, aerospace engineering breeding will have more launch opportunities. China's aerospace engineering breeding mechanism research and application development platform to create conditions.

At the beginning of this year, the aerospace engineering breeding technology and industry were included in China's "12th Five-Year Plan" strategic emerging industries planning. National support policies have been introduced one after another. The core contents are to strengthen the research and development of aerospace engineering breeding technology and to promote its industrialization process; to form a space-laden long-term effective mechanism; to promote space breeding services to modern crop seed industry systems.

At present, the varieties of crops selected and cultivated in China for space breeding involve grain crops, vegetables, flowers, forest trees, economic crops, and oil crops. Most of these varieties have passed the examination and approval of national varieties and have achieved good social and economic benefits. Among them, carrying rice DH-7 compared with the control group earlier earing, maturity earlier than the conventional control group 20 to 25 days.

The reporter learned that during the "12th Five-Year Plan" period, China Aerospace Science and Technology Corporation will undertake the mission of launching hundreds of satellites (spacecrafts, detectors). This also means that in the future China will have unique conditions for space breeding, and will make new breakthroughs in the research, development and application of aerospace engineering breeding.