Text | "China Science News" reporter Li Sihui
In 1994, a sensational article caused an uproar in the United States.
The article believes that with the increase in population and changes in consumption structure, as well as the advancement of urbanization and industrialization, China's food supply in 2030 will be 20% lower than that in 1994, facing a huge food shortage, and the world will not be able to feed China at that time, which will lead to a global food crisis.
The 141-page article, full of pessimism and bias about China, was headlined "Who Will Feed China." In 1995, the author of the article, Lester Brown, published the book "Who Will Feed China", which once again attracted the attention of the international community.
"How can China's vast land and water systems not feed the Chinese?!" a young Chinese who is visiting the University of California, San Diego, also paid attention to the relevant discussion. He took Brown's assertion for granted that it was completely irresponsible. The young man's name was Gui Jianfang, and he was an associate researcher at the Institute of Hydrobiology of the Chinese Academy of Sciences (hereinafter referred to as the Institute of Hydrobiology) at the time.
"Although China has a large population, we have both traditional wisdom and a lot of scientific and technological innovation in food production. In the case of freshwater fish, for example, there is almost no concept of freshwater aquaculture in the United States, and in Brown's calculations, aquatic products that can provide large amounts of protein are completely ignored. Gui Jianfang made up his mind that after returning to China, he would devote himself more actively to the research of freshwater fish genetics and breeding, and provide more adequate freshwater fish food for Chinese.
A unique way to breed
Crucian carp is delicious and nutritious, and has been a nourishing product for the Chinese since ancient times. However, wild crucian carp grow slowly and produce low yields, growing less than 0.1 kg a year on average. In the 70s of the last century, Jiang Yiqi, a researcher at the Institute of Aquatic Sciences, witnessed the situation that many patients and mothers could not buy crucian carp with "special fish tickets".
With the vigorous support of the Chinese Academy of Sciences and the Institute of Aquatic Biology, Jiang Yiqi led the scientific researchers of the crucian carp research group to travel all over the north and south of the Yangtze River in 1976, to eat and sleep in the open air, to study carefully, systematically investigate the resources of crucian carp on the mainland, consult a large number of domestic and foreign literature, and carry out experiments on the mating and breeding of crucian carp in different combinations. The idea of breeding a new species of crucian carp was hatched.
They found that the silver carp in Fangzheng County, Heilongjiang Province has the characteristics of unisexual female reproduction, so they developed a way to induce reproduction with heterologous sperm such as carp, and used the male carp of Xingguo in Jiangxi Province to "mate" with them, and created a unique way to breed "heterogenetic silver carp".
Tall physiognomy silver carp
The progeny of ordinary crucian carp reproduces after the egg is fertilized, and the sperm forms a spermatopronucleus in the egg plasm, which is fused by the spermatopronucleus and the egg pronucleus to develop into a small fish. The eggs of the silver carp also need to be "fertilized", but it does not fuse with the sperm nucleus of the red carp, and only needs sperm to stimulate the egg nucleus to develop into offspring on its own, and all of them are females.
This unique method of "heterospermous gynogenesis" was first discovered and elucidated by scientists from the Chinese Academy of Sciences in mainland China, and applied to fish genetics and breeding research. As an early pioneer, Jiang Yiqi deeply realized that the discovery of the gynogenous reproduction mode and the development of the application potential of the silver carp are unprecedented research, not something that can be completed by one generation. He began to pay attention to young people who were aspiring and had the potential to train them.
In 1984, Gui Jianfang, who was a graduate student at Wuhan University, participated in the graduation thesis defense according to the regulations. His supervisors, Professor Yu Xianjue and Professor Zhou Jun, specially invited Jiang Yiqi, who had made breakthroughs in the breeding of silver carp, to serve as a member of the defense committee. After listening to Gui Jianfang's defense, Jiang Yiqi was like a treasure and invited this simple young man to join the Institute of Aquatic Sciences to engage in the research of silver carp.
In the traditional understanding, the growth rate of crucian carp is slow, the growth rate is not large, the yield is small, and the fishermen are not highly motivated to breed.
In order to expand the scope of experiments and promotion, researchers traveled non-stop from Heilongjiang in the north, Guangdong in the south, Sichuan in the west, and Fujian in the east. Due to the wide feeding habits, few diseases, and growth advantages of heterogeneous silver carp, it was soon regarded as a "cornucopia" by breeding units and farmers, and was praised as "the crown of crucian carp" by the masses.
In 1986, Hongshan District of Wuhan City adopted polyculture, stocking and other ways to breed heterogeneous silver carp, without affecting other fish breeding, without additional bait and fertilization, the output of heterogeneous silver carp reached 160,000 kilograms, a net increase of 500,000 yuan. Heterogeneous silver carp farmed in Guangdong grew to 1.25 kg at 18 months.
By the 90s of the last century, the heterogeneous silver carp has settled in 23 provinces and more than 1 million acres of aquaculture water surface. This scientific research achievement, which invested only 60,000 yuan, has created an annual output value of more than 100 million yuan after its transformation and application.
The production and application of heterogeneous silver carp and the theoretical research on gynogenetic reproduction are not only the first in China, but also the first in the world, and have been highly concerned and recognized by ichthyologists at home and abroad.
Create miracles of life
In 1991, Gui Jianfang's name appeared in the list of awards for young scientists of the Chinese Academy of Sciences. According to the regulations at that time, winning this award gave you the opportunity to study abroad. Gui Jianfang decided to go to the United States to seek cutting-edge knowledge and technology in fish breeding with a deeper theoretical foundation and more precise research methods. There, he met Fu Xiangdong, a former classmate at Wuhan University, and joined his newly established laboratory.
In two years, Gui Jianfang and Fu Xiangdong published two papers in Nature and the Proceedings of the National Academy of Sciences, mastering the systematic knowledge and research skills of cell biology and developmental genetics. When he was about to return to China, his peers advised him: "Why don't you stay here? The United States is the most qualified to make you a great scientist." "I'm going back to my home country, where there's a job that I have to do and that has significant R&D potential," he said.
In the summer of 1994, Gui Jianfang returned from the United States and returned to the Institute of Aquatic Sciences, just in time for the National Natural Science Foundation of China to launch the National Science Foundation for Distinguished Young Scholars. After the application and defense, he was funded by the first National Science Fund for Distinguished Young Scholars. With the support of the Institute of Aquatic Sciences, he established the Fish Cell Engineering and Developmental Genetics Group. Since then, he has devoted himself to further research on silver carp. In the following 30 years, he led the team to investigate more than 50 sample sites in major rivers, rivers and lakes across the country, taking nearly 5,000 samples and identifying and evaluating them with molecular genetic markers. They found that the reproductive methods of silver carp are extremely flexible and diverse, and it is completely possible to open up new breeding technology paths and breed new varieties of crucian carp with better quality based on the heterozygotic silver carp materials previously created by heterospermic female reproduction.
For many sleepless nights, researchers trawled nets in broodstock ponds, aphrodisiacized, artificially inseminated, and artificially debonded, and beside the hatchery loop, they carefully observed, cared for, and analyzed the reproduction of silver carp like nurses. The pearl-like fertilized eggs, with the flowing water of the hatching ring rotating and tumbling day and night, finally gave birth to a new life - the heterogeneous silver carp "Zhongke No. 3".
Allogeneous silver carp "Zhongke No. 3"
In 2013, the Chinese Academy of Sciences launched the "Molecular Module Design Breeding Innovation System" project, trying to use modern biotechnology such as "molecular modules" to create systematic solutions and new breeding technologies for cultivating a new generation of super varieties, providing core strategic support for ensuring food security in the mainland, and carrying out a subversive revolution on traditional breeding technology.
Based on the new technology of heterospermic gynogenetic reproduction, the research team of the Chinese Academy of Sciences identified the molecular modules that play a key role in the excellent quality of Wuchang fish, and used these molecular modules to screen and identify the breeding parents. Finally, a new heterogeneous silver crucian carp variety "Zhongke No. 5", which was cultivated by the combination of parthenogenesis and molecular modules, was born.
The juvenile fish of "Zhongke No. 5" that has just come out of the membrane
At present, in the mainland crucian carp farming, "Zhongke No. 3" and "Zhongke No. 5" account for about 70% of the output of the main crucian carp breeding area. This means that for every 10 crucian carp eaten by Chinese, 7 originate from a Chinese Academy of Sciences research team.
Heterogeneous silver carp "Zhongke No. 5"
In the past 30 years, the achievements of heterogeneous silver carp cultivation, natural gynonuclear reproductive mechanism and the cracking of the genetic basis of reproductive mysteries have won one second prize of the National Science and Technology Progress Award (1985) and two second prizes of the National Natural Science Award (1995 and 2011).
After the successful cultivation of the new variety of heterogeneous silver carp "Zhongke No. 3", it coincided with the launch of the construction of the bulk freshwater fish industry technology system by the former Ministry of Agriculture. With the support of system post experts and system station managers, scientists from the Chinese Academy of Sciences donated new varieties such as "Zhongke No. 3" to seedling breeding farms in Hubei, Guangdong, Jiangsu and other places, and also provided door-to-door technical guidance on seedling breeding. Taking Gui Jianfang as an example, he goes to all parts of the country every year to carry out more than 100 aquaculture technology trainings and train more than 5,000 fishermen.
The research team is also promoting the heterogeneous silver crucian carp series on a large scale across the country to accelerate the development of the crucian carp industry – the production of crucian carp in mainland China has increased from 48,000 tons in 1983 to 2.85 million tons in 2022.
With the joint efforts of many scientists in the field of aquaculture and the proof of the market, people have gradually realized that aquaculture can bring huge economic benefits and greatly meet people's nutritional needs. At present, China's aquaculture production accounts for about 60% of the world's total, providing nearly one-third of animal protein for Chinese consumers, and is an important food source for Chinese.
In 2008, Lester Brown went on a field trip to China and saw a completely different situation than he had predicted back then. Chinese not only have a continuous bumper harvest of grain, solving the problem of filling their stomachs, but freshwater aquaculture is also booming, which greatly fills people's demand for animal protein intake.
Lester Brown could not help but lament the good performance of freshwater aquaculture in China, and believed that aquaculture, as the most efficient way of producing animal protein, has made an important contribution to ensuring food security in China and the world.
Facts speak louder than words, and time will tell. From the question of "who will feed China" to the admiration that "China's aquaculture industry is a major contribution to the world", it took Chinese more than a decade to disprove the fallacy of some Western experts. This embodies the courage and wisdom of the mainland's economic policymakers, the diligent cultivation and hard-working efforts of the vast number of farmers and fishermen, and the painstaking efforts and efforts of scientists in the fields of grain crops, poultry and animal husbandry, and aquaculture.
In June 2022, the Food and Agriculture Organization of the United Nations (FAO) released the State of World Fisheries and Aquaculture (FIF) study, which proposes to strive for a blue transformation that contributes to the realization of the 2030 Agenda for Sustainable Development and conserves natural resources while addressing food security. This means that China's aquaculture experience is being advocated and promoted around the world.
Knock out the small intermuscular spines
In the past two years, scientists from the Chinese Academy of Sciences have been working to solve a "long-standing and difficult" problem that restricts the promotion of crucian carp - there are many small intermuscular spines. For a long time, many elderly people and children do not like to eat crucian carp because they are "afraid of thorns", and people in some Western countries do not eat all freshwater fish because of this.
In 2021, Gui Jianfang's team collaborated with the team of Gao Zexia, a professor at Huazhong Agricultural University who has identified the main gene that regulates the development of intermuscular spines, in an attempt to create a heterogeneous silver carp without intermuscular spines. Thanks to the revelation of double triploidy, Gui Jianfang's team quickly identified the corresponding two partial homologous genes in the silver carp, and tracked the occurrence and ossification of the intermuscular spine of the silver carp.
The researchers found that if only one partial homologous gene was knocked out, the development of intermuscular spine was not affected, and only by knocking out two partial homologous genes and their six alleles at the same time could a mutant of the silver carp with complete absence of intermuscular spines be created, that is, a heterogeneous silver carp with no small spines at all. These mutants have been bred for several generations, laying the foundation for the development of new lines of allogeneic silver carp without intermuscular spines. Looking at these "new silver crucian carp" that had been knocked out of the intermuscular thorns swimming smartly in the water, Gui Jianfang showed a gratifying smile.
"Gene editing is like revising an article, editing one or two bases of the main gene that controls the growth of the intermuscular spines of the silver carp, so that it doesn't work, and the spines can't grow. Gui Jianfang said, "Aiming at such a trait that is annoying to eaters, our breeding goals are more precise, more targeted and more effective, which is a qualitative improvement." ”
Do a good job of silver carp big article
Why can a small silver carp make so many "articles"?
Wang Zhongwei, a researcher at the Institute of Aquatic Sciences, said: "The reason why the silver carp is versatile is that it has a unique genetic basis of double triploid, which makes it an inexhaustible 'treasure house'. As we continue to discover its evolutionary mechanism, we can continue to open up the path of breeding technology, continue to create miracles of life, and meet the needs of aquaculture. ”
In 2012, the team of the Institute of Aquatic Sciences discovered the double tetraploid silver carp and found that ploidy changes can drive the transformation of silver carp from unisexual gynogenesis to sexual reproduction of both sexes, and from sexual to parthenogenesis, which leads to the evolution mechanism of clonal diversity and genetic diversity, and opens up a technical path for multi-genome reconstruction to synthesize gynogenetic heteropolyploidy, which is expected to breed a new line of "Zhongke 6". This new strain grows faster and is more resistant to disease.
Candidate line of heterogeneous silver carp "Zhongke 6".
Lu Meng, an associate researcher at the Institute of Aquatic Sciences, introduced that in 2023, under the leadership of Gui Jianfang, the team will further develop a technical route for the efficient creation of sterile heteropolyploidy in the synthesis of new double triploid silver carp based on the reproductive discovery of "non-meiotic fusion", which is expected to be transformed into a precision breeding route of "controllable fertility" in the future.
"From the perspective of application prospects, this technology can help to create new germplasm very efficiently, so that new varieties can grow faster, have stronger disease resistance, and be more suitable for large-scale farming. He said.
Sterile heteroploid silver carp Courtesy of the Institute of Aquatic Biology
In the early days of the founding of New China, Chinese people could only eat an average of one kilogram of aquatic products a year, but today the average person can eat nearly two kilograms a week. The major transformation of the aquaculture model has contributed the Chinese wisdom of aquaculture to the world. China's aquaculture technology has gone abroad and has been successfully applied in Africa, Southeast Asia, the Middle East and other regions.
In this process, in order to cultivate heterogeneous silver crucian carp and let every Chinese eat delicious crucian carp, three generations of scientists from Jiang Yiju to Gui Jianfang to Wang Zhongwei and Lu Meng have worked hard for decades.
"Scientists of the past generation have often taught us that those who do aquatic breeding must really write their papers in the big rivers and fish ponds of the motherland, and truly solve some practical problems in China's aquatic seed industry. Rumon said.
Today, Gui Jianfang, who has been dealing with silver carp for nearly 40 years, is pleased to see that a new generation of young people is thriving into the backbone of scientific and technological innovation. He firmly believes that with the joint efforts of generations of researchers, China will cultivate more high-quality varieties, and aquaculture technology will be promoted to more places, so that more people will be "mouthful".