China News Service, Beijing, December 5th (Reporter Sun Zifa and Zheng Yingying) The reporter learned from the Chinese Academy of Sciences (Chinese Academy of Sciences) on December 5th that the research team of the Center for Excellence in Molecular Plant Sciences of the Chinese Academy of Sciences has completed rice and Arabidopsis breeding experiments on the Chinese Space Station. For the first time in the world, the whole life cycle cultivation of rice from seed to seed has been realized in orbit, and rice seeds in space have been successfully harvested.

Pictures of native rice and ratooning rice in space rice, showing the phenotype of open panicles and glumes in space rice.

Photo courtesy of Center for Excellence in Molecular Plant Science, Chinese Academy of Sciences

The experiment lasted 120 days and collected 3 samples

　　The third batch of space science experiment samples of the China Space Station returned to the ground with the return capsule of the Shenzhou 14 spacecraft on the evening of December 4, and were delivered to the China Manned Space Engineering Space Application System led by the Chinese Academy of Sciences at the landing site.

This batch of samples includes rice and Arabidopsis seeds that have experienced a full life cycle of 120 days. They arrived in Beijing on the 5th and were confirmed to be in good condition before being delivered to relevant experimental scientists.

　　The Center for Excellence in Molecular Plant Science of the Chinese Academy of Sciences said that Zheng Huiqiong's research team undertook the life science project of "Molecular Mechanisms of Flowering Regulation of Higher Plants under Microgravity Conditions" on the Chinese Space Station, and it was the first time in the world to carry out the whole life cycle cultivation of rice from seed to seed in orbit. experiment.

At the same time, based on the premise that flowering is the premise of seed formation, the research team also used the model plant Arabidopsis to systematically study the impact of space microgravity on plant flowering.

　　The on-orbit experiment lasted a total of 120 days, starting from the injection of nutrient solution on July 29, 2022, and ending on November 25, 2022. The entire life cycle of Arabidopsis and rice seed germination, seedling growth, flowering and seeding was completed.

During the experiment, the astronauts carried out three sample collections in orbit, including the collection of rice samples at the booting stage on September 21, the collection of samples at the flowering stage of Arabidopsis thaliana on October 12, and the collection of samples at the maturity stage of rice and Arabidopsis seeds on November 25. .

　　After the samples were collected, the samples at the flowering or booting stage were stored in a low-temperature storage cabinet at -80°C, and the samples at the seed maturity stage were stored in a low-temperature storage cabinet at 4°C.

According to the plan, after returning to the ground with Shenzhou 14 to complete the handover, these samples will be transferred to a laboratory in Shanghai for further testing and analysis.

The image of the process of regenerating rice in space, the time in the figure is the number of days after cutting the plants.

Photo courtesy of Center for Excellence in Molecular Plant Science, Chinese Academy of Sciences

Complete the three major experimental contents and compare with the ground control

　　Researcher Zheng Huiqiong pointed out that this space project mainly completed three experimental contents:

　　One is to complete the cultivation experiment of the whole life cycle of rice from seed germination, seedling growth, earing and seed setting in orbit and analyze it by acquiring images;

　　The second is that the space ratooning rice was successfully cultivated and matured seeds (second stubble) were produced after the pruning was completed.

　　The third is to complete on-orbit image observation and analysis of Arabidopsis seed germination, seedling growth, and flowering key genes regulated by three different biological clocks in response to space microgravity, and collect samples on-orbit.

　　By analyzing the images acquired in space and comparing them with those on the ground, the research team found that space microgravity can affect various agronomic traits of rice, including plant height, tiller number, growth rate, water regulation, light response, flowering time, and seed development. The process and seed setting rate have many influences.

The space application center of the Chinese Academy of Sciences successfully handed over the returned samples to relevant experimental scientists.

Photo courtesy of Space Application Center, Chinese Academy of Sciences

　Space breeding experiment yields series of preliminary discoveries

　　Zheng Huiqiong said that the breeding experiment carried out on the Chinese space station has made many preliminary important discoveries, mainly including the following four aspects:

　　One is that the plant type of rice becomes looser in space, mainly because the angle between stems and leaves becomes larger; dwarf rice becomes shorter, and the height of tall rice is not significantly affected.

In addition, the spiral upward movement of rice leaf growth controlled by the circadian clock is more prominent in space.

　　The second is that the flowering time of rice space is slightly earlier than that of the ground, but the filling time is extended by more than 10 days, and most of the glumes cannot be closed.

Both flowering time and glume closure are important agronomic traits of rice. Both of them play an important role in ensuring sufficient reproductive growth of plants and obtaining high-yield and high-quality seeds. This process is regulated by gene expression, and the returned samples will be used for further analysis.

Researcher Zheng Huiqiong from the Molecular Plant Excellence Center of the Chinese Academy of Sciences decomposed and solidified the returned experimental samples.

Photo courtesy of Space Application Center, Chinese Academy of Sciences

　　The third is to conduct ratooning rice experiments in space and obtain the seeds of ratooning rice.

Two spikes of rice can be regenerated 20 days after cutting the plant, which shows that regeneration rice is feasible in a closed environment with a small space, and it also provides new ideas and experimental evidence for the efficient production of space crops.

This technology can greatly increase the yield of rice per unit volume, and it is also the first regenerative rice technology tried in space in the world.

　　Fourth, it is the first time to study the key genes of the spatial circadian clock regulating photoperiod flowering.

Using gene mutation and transgenic methods, three kinds of Arabidopsis with different flowering times were constructed, namely early flowering, delayed flowering and normal flowering (wild type). Through the observation and analysis of the growth and development of Arabidopsis in space, It was found that the response of key flowering genes to microgravity was significantly different from that on the ground, and the flowering time of Arabidopsis that bloomed earlier on the ground was also greatly prolonged under microgravity conditions.

　　In addition, after the circadian clock gene mutation, the hypocotyl of Arabidopsis thaliana was excessively elongated, indicating that the expression of the circadian clock gene is very important for maintaining the normal shape of Arabidopsis thaliana in space and adapting to the space environment. Adapting to the microgravity environment of space provides a new direction.

The research team will further use the returned materials to further analyze the molecular basis of Arabidopsis adaptation to the space environment.

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