Yuan Longping, a great world hunger fighter

Abstract

Yuan Longping, is known as ‘Father of Hybrid Rice’, was born into an intellectual family in Beijing on 13 August 1929 and passed away on 22 May 2021, in Changsha, Hunan Province, China. He was an academician of the Chinese Academy of Engineering, a foreign associate of the National Academy of Sciences of the United States and former director general of China National Hybrid Rice Research & Development Center. He was a person who had been more passionate about his job development of hybrid rice for food security in the world and was full of the sense of mission and responsibility. This builds up his prominent scientific spirit: persistent pursuit and innovating forever. When Yuan was a boy, his teacher once took the pupils to go on an excursion. In a horticulture garden, he saw green grass, fresh flowers, red peaches and bunches of grapes. The lively energy in the great nature gave him a deep impression in his young mind. At that time, an American comic movie ‘Modern Times’ described the countryside as a beautiful heaven and Yuan was attracted to the movie. The superposition of the above two motivated him to study agriculture. In 1949, Yuan completed his high school courses and enrolled at the Southwestern Agricultural College in Chongqing, majoring in agronomy. This marked the beginning of his lifelong work in agriculture. After his graduation from college in 1953, Yuan did a teaching job at An-jiang Agricultural School in An-jiang county in the western mountainous area of Hunan, China, and married Deng Ze in 1964. As a teacher, he taught botany, crop cultivation, breeding and genetics and even Russian language. Therefore, while teaching, he conducted scientific experiments to improve food crop production, involving asexual crosses between crops, using Michurin's theory. However, after 3 years of research, he found that the theory was incorrect, so he gave up asexual crossing experiments and recognized Mendel's modern genetics. Just at that time, he happened to discover a ‘Natural rice hybrid’. However, in the early 1960s, no one thought that hybrid vigour can be exploited in a self-pollinated crop such as rice and no solutions for seed production of high-yielding hybrid in self-pollinated crop. But Yuan believed that heterosis was a universal phenomenon, and rice was no exception. The ‘Natural rice hybrid’ enlightened his courage to challenge classical theory. He made up his mind to research hybrid rice and started to explore the mechanism of heterosis utilization in rice after the discovery of this extraordinary hybrid in 1964. As widely known, heterosis is best expressed in the first-generation hybrid of two genetically distinct parents. Rice is a self-pollinated crop. Its flower is tiny, and one flower can only produce one grain. These characteristics make it impossible to remove pollen-producing anthers manually and thus severely prevent the commercial application of hybrid in rice before the 1970s. Yuan discovered the male sterile rice plants in 1964 and 1965 and then published his first research paper on rice male sterility in the Chinese Science Bulletin, which initiated China's hybrid rice researches in 1966. In this landmark paper, he rightfully predicted that rice heterosis could be utilized to increase yield through the development of male sterile (or A) lines, maintainer (or B) lines and male restore (or R) lines and described the nice blueprint of utilizing rice heterosis successfully. Because Yuan insisted on his research on developing hybrid rice in the late 1960s, he moved to Hainan and Yunnan from Hunan in the winter like a migratory bird. It was on Hainan Island in 1970 that a male sterile plant in wild rice—‘WA’ was found. This nature wild male-abort rice provided a crucial genetic tool in the birth of China's commercial hybrid rice and confirmed Pasteur's famous aphorism ‘Chance favors the prepared mind only’. This led to the promising discovery progress in the development of hybrid rice. After 9 years of hard work, Yuan and his research team successfully developed the three genetic lines in 1973, that is, male sterile line, maintaining line and restore line or A, B and R line, which are essential for developing hybrid rice. In 1974, he selected the first hybrid variety Nanyou No.2, which showed very strong heterosis and high yield potential. In 1975, technology for commercial hybrid seeds production was completed. One year later, hybrid rice was released for commercial production. Thus, Yuan is considered as the first scientist to successfully alter the self-pollinated characteristics of rice and facilitate the large-scale production of hybrid rice, which has 20% more yield than elite inbred varieties. Dr. M.S. Swaminathan, the former director general of the International Rice Research Institute (IRRI) gave a speech at an international rice conference at IRRI in 1982: ‘Yuan Longping, we called him the father of hybrid rice, is well-deserved, and his success is not only the pride of China, but the pride of the world, his achievement has brought the gospel to the world’. He indicated in his message to Yuan on the occasion of Yuan's 80th birthday: ‘You took the unknown path into an area full of skepticism and made the impossible possible-achieve the rice hybrid miracle’. Yuan had a dream called the dream under the rice panicle. Once, he dreamed that the rice plants were as high as a sorghum plant; the panicles were as large as besoms; and the grains were as big as peanuts. Yuan and his assistants were enjoying the shade under the rice panicles. Actually, it is a dream of rice high yield. Indeed, Yuan was a person who was not satisfied with his past success. He continued dreaming of pursuing the dream of rice high yield. After achieving the success of the three-line (A, B and R) hybrid rice, he kept on exploring and had always been thinking about how to develop new approaches to enhance the heterosis level and simplify the methodology for hybrid rice breeding. In 1986, Yuan proposed the ‘three-step’ strategy of developing hybrid rice. He was a responsibility expert for the programme of developing two-line hybrid rice also. By composition of photo-thermo-sensitive genic male sterile (PTGMS) and restorer line (R), the two-line system (PTGMS, R) is simpler than the three-line system (A, B and R), that is, a system that would not require a maintainer line (B), or the PTGMS can plan as both the sterile line (A) and the maintainer line (B), because the PTGMS on one hand shows sterility under the condition of high temperature and long sunshine and on the other hand returns to normal fertility under the condition of flat temperature and short sunshine. So, people can use the PTGMS as sterile line (A) to produce the hybrid rice seeds in hot summer and reproduce PTGMS itself (as maintainer line, B) when the temperature is relatively low and the sunshine is relatively short in spring and autumn. Under Yuan's wise leadership and technical guidance, his research team succeeded in developing a whole package of two-line hybrid rice technology in 1995. Moreover, in the new 21st century, the world faces risks that rice production fails to meet the demand of population increase and planting area recession. Yuan assumed the responsibility to develop super hybrid rice. He laid out a road map: a combination of morphological improvement, inter-subspecies hybridization and foreign genes for high yield introduction with molecular biotechnology. Under the guidance of this road map, his team fulfilled the first, second, third and fourth stage yield goals in a large planting area in the year of 2000 (10.5 t/ha), 2004 (12 t/ha), 2012 (13.5 t/ha) and 2014 (15 t/ha), respectively. To exceed the target of 18 t/ha super hybrid rice programme, he put forward a new strategy again. That was to raise the height of the rice plant on the base of lodging tolerance. He considered that it would help increase rice yield potential. Yuan used to say ‘To pursue crops' high yield is an eternal subject’. The important progresses of new super hybrid rice varieties' demonstration have been made continuously because the above targets were achieved. A new hybrid, Xiangliangyou 900, yielded more than 16 t/ha in 2015, 2016 and 2017 at a 6.8 ha of demonstration in Gejiu, Yunnan. More excitingly, an average yield of 17.28 t/ha for large-scale rice cultivation was achieved at the same demonstration location in 2018. It was the highest yield level in large-scale cultivation in the world. In 2022, a new yield record has been created by variety Zhuoliangyou 1126 with the yield of 18 t/ha on hectare level in the Gejiu demonstration location again. Besides, Yuan's team launched the breeding research of saline-alkali-tolerant hybrid rice, aiming at the application in about 1 billion ha of saline-alkali land in China. The team also carried out the third-generation hybrid rice research, facilitating the integration of freedom of choice of parents for hybrids in two-line system with stable sterility of male sterile line to develop elite hybrids. The representative variety for the third-generation hybrid ‘Sanyou No.1’ has been planted as a late one for double rice a year in Hunan Province since 2019. Its growth period was 125 days, and the yield reached more than 13.5 t/ha. It has made good results in Hengnan County, Hunan Province, and the total yield of double-cropping rice within a year reached 22.96 t/ha in 2020. With Yuan's relentless pursuit and innovation, his research resulted in the realization of increasing rice yield potential. And also, the utilization of rice heterosis has offered an effective way for large-scale improvement in per unit output on current condition. Now, the planting area of hybrid rice expanded greatly, reaching around 1.67 × 107 hm2 in recent years and accounting more than 50% of a total one rice-growing area in China. In recent years, the average yield of rice is approximately 6.45 t/hm2, in which the average yield of hybrid rice is 7.5 t/hm2 and that of conventional rice is 6.15 t/hm2 in China. The two-line hybrid rice is planted 3 million ha annually in China and not only outyielded the three-line hybrids by about 10% but also is popular with good quality. Hybrid rice has saved thousands of lives in a heavily populous China with limited acreage of farming land in the last 30 years. This remarkable success has helped transform China from food deficiency to food security within three decades despite the significant increase in its population. The development of hybrid rice helps China solve food shortage problem successfully and provides additional income to thousands of farmers today. Because of its great success, hybrid rice is honoured as the second ‘Green Revolution’. Yuan's lifelong pursuit was ‘Developing hybrid rice for the welfare of the people all over the world’. Acting on his belief that science should have no boundaries between countries, he shared his knowledge, experience, ideas and valuable breeding materials with scientists outside China to enthusiastically extend hybrid rice technology to other countries. In early 1980s, he donated the indispensable and unique cytoplasmic male sterile (CMS) line to the IRRI; many countries obtained this precious resource through IRRI to develop new male sterile lines and hybrid varieties. Those hybrid rice varieties are now widely planted in many Asian countries. From then on, Yuan visited IRRI cooperative research and technology exchange for more than 30 times. In 1980, China's hybrid rice was transferred to the United States as the first agricultural patent technology. Yuan's research institute had established cooperation relations with the RiceTec Inc., an American seed company, since 1992. Yuan had been to the United States for more than 10 times to guide the research and production of hybrid rice there. He was appointed as the chief consultant of the Food and Agriculture Organization (FAO) of the United Nations and travelled to India, Vietnam, Bangladesh and the Philippines many times. He believed that by taking advantage of China's world leading expertise on technologies and successful experience on hybrid rice research and application, more experts would be able to be trained for the promotion and application of hybrid rice technologies. Up to now, Yuan's research institute and teams already trained over 14,000 scientists or breeders from more than 80 countries. Through such training, Yuan not only imparted his knowledge and wisdom to the trainees but also played as an envoy and erected the bridge of better consolidation of the friendship among all of the trainees and external development of hybrid rice in Asian, African and South American countries. Yuan's concerns went beyond China's food supply and extended to the enormous problem of world hunger. As a result, through Yuan's efforts to extend hybrid rice technology to other countries, hybrid rice have been commercialized spreading throughout Asia and Africa and the Americas including India, Vietnam, Bangladesh, Pakistan, Philippines, Brazil, Madagascar and the United States, where hybrid rice occupied over 8 million ha in 2020. Farmers in more than 10 other countries besides China have thus benefited from his excellent work. The famous American Economist Professor Don Paarlberg commented on his book of Toward a Well-fed World: ‘It illustrates the utility of agricultural science, the caprice of chance, and the accomplishment of a dedicated man … Yuan Longping has bought China valuable time with which to bring down the rate of population growth. As agricultural science advances, the threat of famine retreats. Yuan led toward a well-fed world’. In 2019, for the celebration of the 70th anniversary of the founding of the People's Republic of China, the ‘Medals of the Republic’ were awarded to eight people, including Yuan Longping, in grand recognition of exemplary meritorious figures who have made outstanding contributions to the construction and development of New China and in the promotion of the national spirit and the spirit of the times. In recognition of Yuan's work, he had been bestowed a number of awards and honours also, which includes four of the top prizes in China: the Special-class National Invention Prize in 1981, which was the first of the country; the first National Supreme Scientific and Technology Award in 2001; the Special-class National Science and Technology Award in 2014; and about 20 awards in the world, including the 1987 UNESCO Science Prize, the 1995 FAO World Food Security and Sustainability Medal, the 2004 World Food Prize in the United States and the 2004 Wolf Prize in Israel, and also in 2006, he was elected as a foreign associate of the National Academy of Sciences of the United States. Yuan published more than 70 articles and six monographs on hybrid rice research and development. The book Hybrid Rice Breeding and Cultivation has been recognized as an authoritative reference on hybrid rice technology within China, and two others, A Concise Course on Hybrid Rice and Technology of Hybrid Rice Production, are considered to be primers for hybrid rice technology both within and outside China. Especially, the book, Technology of Hybrid Rice Production, was published by FAO in 1995 and has been translated into other languages. It is considered as the best instruction book in international training of hybrid rice. In 1999, the International Commission on Asteroid Nomenclature named the 8117 asteroid as Yuan Longping Asteroid. Now, Yuan Longping has really been transformed into Yuan Longping Asteroid, hanging high in the sky, overlooking the earth. Yuan Longping's lifelong commitment to putting an end to world hunger has brought mankind one step closer to the full realization of his inborn rights. Along the road, our world has become more peaceful and human beings more humane and decent.