Reporter Wang Jiayi
As a rare nutrient, selenium is one of the essential trace elements of the human body, which has a variety of bioactive functions and plays a very key role in human health. A variety of diseases of human health are related to the lack of selenium, and the data show that the selenium intake of Chinese residents is seriously insufficient, and the problem of "hidden hunger" of selenium nutrients is very serious. The biosynthetic production of selenium-rich vegetables has expanded human access to organic selenium. At present, synthetic biology is booming and has become a hot track at home and abroad. How to grasp the major opportunities of a new round of scientific and technological revolution and industrial transformation, and promote the development of synthetic biology technology in the direction of practicality and industrialization?Wang Hanzhong, academician of the Chinese Academy of Engineering, said at the 2023 International Future Agri-Food Top 100 Conference in the Central Plains Agricultural Valley that biosynthesis has the three advantages of being fast, efficient and green, and the biosynthesis of rare nutrients is becoming a new track for agriculture in the future.
Selenium nutrient "hidden hunger" is a serious problem
A variety of diseases that affect human health are related to the deficiency of selenium, such as "Keshan disease" and "large bone joint disease", and major human health problems such as immunocompromise, cancer and cardiovascular and cerebrovascular diseases are also related to insufficient selenium intake. The data shows that the selenium intake of Chinese residents is seriously insufficient, only 0026—0.032 mg days, selenium nutrients "hidden hunger" problem is serious. As an essential nutrient for the human body, selenium has a biological half-life of only 11 days, and the body cannot synthesize it on its own, so it must be constantly replenished from the outside.
Selenium in nature exists in two forms: inorganic selenium and organic selenium. Inorganic selenium is generally selenite and selenite, which has low bioavailability and high toxicity, and is not suitable for direct consumption by the human body. Organic selenium is mainly a selenium amino acid, which participates in protein synthesis in the body, is easy to store and absorb in tissues, and can be quickly utilized after being absorbed by the human body, effectively improving the selenium deficiency in the human body. Among them, methylselenocysteine is a common form of organic selenium, and it is also the best form of selenium that has been reported to help fight cancer.
Currently, selenium-rich vegetables and grains are the safest and most effective for organic selenium**, but foods rich in methylselenocysteine are scarce. According to the data of the Institute of Geophysical Chemistry of the Chinese Academy of Geological Sciences, China's green selenium-rich land accounts for only 3About 5%. If exogenous inorganic selenium is applied during the planting process, it is also easy to cause secondary pollution.
Wang Hanzhong said that overall, the total amount of organic selenium in China is insufficient, but the demand potential is large, and it is urgent to open up new ways to obtain organic selenium, especially methyl selenium. "In recent years, my team and I have compared the total nutritional quality of more than 100 servings of rapeseed sprouts with 9 common vegetables (4-6 varieties of each vegetable) and found that rapeseed sprouts have a special enrichment function for selenium, and its selenium content is significantly higher than that of other measured vegetables. ”
Biosynthesis increases the selenium content of vegetables
As one of the common vegetables on the table of Chinese people, rapeseed sprout has the origin and evolution of edible origin and delicious taste.
In general, the selenium content is 001—0.1 mg kg of vegetables is considered selenium-rich vegetables. In the non-selenium-rich soil without the addition of exogenous selenium, the selenium content of rapeseed sprout was 0009—0.074 mg kg, indicating that there is great potential for improving selenium content in rapeseed varieties. This is found in non-selenium-rich soils (<04 mg kg) can efficiently enrich selenium and grow selenium-rich rapeseed, which is called the phenomenon of "selenium efficiency". "Based on the discovery of this phenomenon, the vegetable-type 'Super Rapeseed' has become the target of our team's cultivation of new selenium-rich vegetable varieties. Wang Hanzhong said.
In 2019, relying on excellent germplasm resources, Wang Hanzhong's team cultivated the world's first "selenium efficient" vegetable, a new hybrid rapeseed variety "Selenium Ziyuan No. 1", relying on excellent germplasm resources and using modern breeding methods such as polymeric hybridization, microspore cultivation, and molecular marker-assisted selection051 mg kg (Wuchang soil selenium content 0.)172 mg kg).
Wang Hanzhong introduced that this variety has a strong selenium enrichment ability, and the selenium content of rapeseed planted in many non-selenium-rich soils across the country is maintained at 001—0.07 mg kg, and has the characteristics of high calcium, high vitamin C, high amino acids and high zinc. It can be picked two months after sowing, and 3-4 stubbles can be picked at a time of planting, and the yield per mu can reach 600-800 kg, and the supporting dense planting cultivation measures can achieve higher yields.
Later, we cultivated 'Selenium Ziyuan No. 2', which has been widely promoted, and the total selenium content of this variety is 0213 mg kg fresh weight, of which methyl selenium accounted for 476%。Wang Hanzhong said that the use of ultra-high methyl selenium rape biosynthesis technology, methyl selenium efficient enrichment of rapeseed genotype as a bioreactor, supporting the use of facilities, soilless, automated cultivation technology and facilities, the future will further improve the content of rapeseed selenium, increase the proportion of methyl selenium.
A new track has been added to the future of agriculture
Wang Hanzhong said that the biosynthesis of rare nutrients represented by methyl selenium has expanded the way for human beings to obtain organic selenium, and also provided a new choice for the multifunctional development and utilization of rapeseed.
In addition to the biosynthesis of methyl selenium, there is also the biosynthesis of nutrients such as -carotene, vitamin E, ergothioneine, etc. Take ergothioneine as an example, it is a naturally rare amino acid, usually biosynthesized by bacteria and fungi, and was first isolated from ergot mushrooms in 1909, and the plant is mainly used in mushrooms, oyster mushrooms, cereals, and broccoli. Compared with traditional bioextraction or chemical synthesis, biosynthesis technology has increased the yield of ergothioneine by nearly 5 times, thereby achieving low-cost and large-scale production of ergothioneine. In recent years, biosynthesis has gradually affected the future development of human industry and has become the engine for the rapid development of the green biomanufacturing industry.
Wang Hanzhong introduced that the process and industry of artificial synthesis of organic compounds using new organisms designed and constructed is biosynthesis. Among them, the common biosynthesis reactors include microorganisms (such as yeast, E. coli, etc.) and plants (such as rice, rapeseed, etc.). The categories of compounds in biosynthesis include rare nutrients, bioenergy, biomedicine, etc. "Biosynthesis has the three advantages of being fast, efficient and green. It is greener and less expensive than chemical synthesis;Compared with traditional agriculture, it has the advantages of being able to be facility and large-scale, 24 hours uninterrupted, regardless of season, and not affected by the environment, and can truly realize industrial production. He said.
The 14th Five-Year Plan for the Development of the Bioeconomy clearly states that the bioeconomy, including synthetic biology, is a new driving force for China's economic transformation in the future. With the strong support of national policies, Beijing, Shanghai, Shenzhen, Tianjin and other places have successively listed synthetic biology as a key focus area in their development plans.
Therefore, I believe that the biosynthesis of rare nutrients should be a new track for agriculture in the future. Wang Hanzhong said.