Seed source innovation "storing grain in technology"

Recently, at the Xinxiang Experimental Base in Henan Province of the Institute of Crop Science, Chinese Academy of Agricultural Sciences, wheat is about to mature, with beautiful yellowing and a bountiful harvest scene.

Pubingzi 300 is growing well in the fields.

Researcher Li Lihui (fourth from the right) from the Institute of Crop Science, Chinese Academy of Agricultural Sciences, and team members inspected the performance of field materials.

On May 24th, at the Xinxiang Experimental Base of the Crop Science Research Institute of the Chinese Academy of Agricultural Sciences in Henan Province, representatives from research institutions, seed industry enterprises and other breeding units observed the high-yield, stable and strong gluten new lines (varieties) of "wheat ice grass" distant hybridization on site.

The above pictures are provided by the Institute of Crop Science, Chinese Academy of Agricultural Sciences

The wheat harvest site in Laowangpo, Xiping County, Henan Province, covering 10000 acres of high standard farmland. Photo by Wei Baimin

At the end of May, in the experimental base of the Crop Science Research Institute of the Chinese Academy of Agricultural Sciences in Xinxiang, Henan, wheat was about to mature, with rolling waves and a golden color. Among the wheat varieties planted in this field, the team led by Li Lihui, a researcher at the Crop Science Research Institute of the Chinese Academy of Agricultural Sciences, created 90 "Xiaomai Bingcao" long-distance hybrid innovative germplasm, which were planted in a concentrated area of 0.5 acres for each species, creating a spectacular scene. This germplasm is considered an important genetic resource for opening up high-yield wheat breeding pathways in China, providing excellent germplasm resources for wheat breeding innovation and injecting innovative power into achieving technological self-reliance and controllable seed sources in the seed industry.

On May 24th, the field exhibition and effective utilization seminar of the "Wheat Ice Grass" distant hybrid new line (variety) jointly organized by the Crop Science Research Institute of the Chinese Academy of Agricultural Sciences and the Central Plains Research Center of the Chinese Academy of Agricultural Sciences was held in Xinxiang. Representatives from more than 40 research institutions, seed industry enterprises and other breeding units observed 90 high-yield, stable and strong gluten new lines (varieties) of the "Wheat Ice Grass" distant hybrid on site, including the 2023 national approved wheat variety "Pubing03" and 9 new lines currently participating in national regional trials.

Why is the marriage between wheat and ice grass so popular in the industry? "The germplasm of the 'wheat wheatgrass' distant hybridization series displayed this year has shown remarkable diversity after upgrading. These new materials not only maintain the characteristics of more flowers and more fruits, but also have compact plant types and upright leaves. It is worth mentioning that they have shown excellent resistance to current major diseases such as stem rot and scab, and also have the characteristics of high quality and strong tendons." Liu Xu, an academician of the CAE Member and a researcher of the Institute of Operations of the Chinese Academy of Agricultural Sciences, commented.

Overcoming the World Problem of Distant Hybridization

Ice grass plants are one of the closely related wild species of wheat, with extremely strong vitality and excellent drought resistance, cold resistance, and disease resistance. Its spikes are somewhat similar to wheat, but the spikes are large and have prominent characteristics of having a large number of spikelets and small flowers. In addition, it has strong cold and drought resistance, and exhibits high immunity to various wheat diseases. It is considered one of the best exogenous excellent gene donors for wheat improvement.

It is not easy to achieve distant hybridization between wheat and ice grass. Ice grass and wheat may look similar in appearance, but in reality, they have a distant genetic relationship, making hybridization very difficult, "said Li Lihui.

Starting from the 1930s, scholars from some countries hoped to solve this problem, but were not successful until the 1980s. The international wheat research community generally believes that "distant hybridization between wheat and the genus Agropyros" is a dead end.

In 1988, before entering the master's program, when Li Lihui proposed this topic to his supervisor and renowned expert in crop germplasm resources, Dong Yuchen, Mr. Dong kindly advised him to give up. I want to give it a try, and if I can't do it, I'll change the topic. "Li Lihui's persistence convinced the teacher, and then he led two assistants to start researching in the experimental field.

36 years later, in the experimental fields of Xinxiang, Henan, dozens of wheat and ice grass hybrid wheat materials are about to mature. 15 new varieties have been developed using these materials, and there are also 39 reserve new varieties.

What are the challenges of distant hybridization between wheat and ice grass?

There are three major obstacles to distant hybridization: hybridization incompatibility, hybrid sterility, and offspring 'crazy separation'. These problems have never been solved, "said Zhang Jinpeng, a researcher at the Institute of Crop Science, Chinese Academy of Agricultural Sciences. For example, wheat usually matures in late May, while ice grass grows in high latitude areas and has just bloomed. To crossbreed the two, the first step is to adjust the flowering period to the same period. Secondly, it is necessary to address the issue of reproductive isolation in pollination and fertilization of wheat ice grass. Even if pollination is successful, the embryo cannot develop normally, and a set of embryo rescue techniques needs to be developed to obtain hybrid plants.

The conventional breeding technology route is not feasible, so researchers have taken a different approach. Through innovative cultivation of germplasm resources, they have finally broken through the "reproductive isolation" between wheat and ice grass. Under the leadership of Li Lihui, the innovation and utilization team of wheat germplasm resources at the Institute of Crop Science, Chinese Academy of Agricultural Sciences, has created a new technology system for wheat distant hybridization through unremitting efforts. Through a series of innovations such as young pollination, embryo rescue, young ear cell culture, high-frequency induction of heterologous translocation, and development of specific molecular markers, the problem of distant hybridization between wheat and ice grass has been overcome, achieving an important breakthrough in wheat breeding by utilizing excellent exogenous genes of the ice grass genus from "0" to "1".

The team has also completed genome sequencing and resequencing of wild donor species of ice grass, continuously promoting the effective utilization of innovative germplasm and the breeding of new varieties. Using the parent material of the "wheat ice grass" multi grain introgression line, the significantly increased yield of Pubingzi 300, the high-efficiency utilization of nitrogen nutrients of Pubingzi 301, and the high-quality strong gluten new line Pubingzi 4696 with stable performance in multiple ecological areas have been selected and bred. These lines are currently participating in the national wheat variety approval test.

There is great potential for the utilization of innovative germplasm

In the past, improving wheat varieties and increasing yields mainly relied on hybridization between existing promoted varieties. However, long-term hybridization between varieties and extensive application of a few backbone parents have led to a narrowing of genetic variation range, increasingly single variety antigens, and wheat breeding entering the bottle neck stage. Therefore, introducing excellent genes of ice grass into wheat through distant hybridization is a significant task. Among the wild relatives of wheat, ice grass species have many excellent target traits for wheat breeding. By introducing key excellent genes that are currently lacking in cultivated wheat through distant hybridization, not only can yield be increased, but also the ability to resist stress and diseases can be enhanced

The most direct benefit of combining wheat and ice grass is high yield. Li Lihui introduced that in traditional breeding, the number of spikes per acre, the number of grains per spike, and the thousand grain weight are the three factors that affect yield. However, these three factors are negatively correlated with each other, meaning that an increase in one factor often leads to a decrease in the other two factors, making it difficult to increase them simultaneously. The innovative germplasm of "wheat ice grass" has solved this problem, with high yield characteristics of multiple flowers and fruits, and can increase yield by more than 10% compared to the main wheat varieties. It has solved the problem of breakthrough high-yield wheat germplasm shortage in China, especially by discovering the excellent gene cluster of "multiple grains high thousand grain weight effective tillering", which significantly improves the number of grains per spike and thousand grain weight.

The ability to resist stress and diseases has also been greatly enhanced. Research has found that the innovative germplasm of "wheat ice grass" has broad-spectrum resistance to diseases such as powdery mildew, stripe rust, and leaf rust, providing strong support for the cultivation of new varieties with persistent resistance and multiple disease resistance. As of now, the "wheat ice grass" derivative line has been distributed to breeding units nationwide, and 21 new varieties carrying exogenous target genes of ice grass have been cultivated, and 39 new lines have participated in national and provincial trials, covering the main wheat producing areas in China. Among them, the newly approved wheat variety Pubing151 in Gansu and Shaanxi provinces has become the main variety for local diseases such as stripe rust and dryland wheat areas, achieving a new breakthrough in multi resistance breeding.

In the future, an innovative germplasm utilization consortium of 'wheat ice grass' will be established to greatly improve utilization efficiency and strengthen the functional analysis of important genes such as high yield, high quality, and multi resistance from the P genome of ice grass in the innovative germplasm, "said Li Lihui.

The "Wheat Ice Grass" distant hybrid series germplasm materials showcased this year also have the characteristics of high-quality and strong gluten.

Whether noodles are chewy or not is related to the quality of wheat. Medium gluten wheat is mainly used for making traditional pasta such as noodles and Mantou, while weak gluten wheat is mostly used for industrial production such as wine making, while strong gluten wheat is mostly used for making bread, dumplings, Lamian Noodles and other foods. In the past, China had insufficient production of weak gluten and strong gluten wheat, resulting in poor varieties. With the development of agricultural technology, China's own weak and strong gluten varieties have generally caught up with the international advanced level.

From germplasm innovation to effective utilization, although the time is usually long, the impact is far-reaching. We look forward to the research on the distant hybridization of 'wheat ice grass' to promote new breakthroughs in wheat breeding, "said Li Lihui

"This shows that the use of 'wheat wheatgrass' has reached a new level." Sun Qixin, academician of the CAE Member and president of China Agricultural University, said that from germplasm materials to new varieties, from more flowers and more fruits to more resistance, these lines (varieties) have great potential, and should be transformed into production advantages for the benefit of wheat breeding.

Kang Zhensheng, an academician of the CAE Member and professor of the Northwest University of Agriculture and Forestry Science and Technology, has recently been focusing on how to improve the comprehensive disease resistance of wheat varieties.

At this seminar, the new distant hybrid lines and varieties of "wheat ice grass" showcased, commonly known as "Pu Bing", have a genetic difference of over 60% compared to the wheat varieties currently promoted for cultivation in production. These strains (species) have 20-40 sister strains, which will try to meet the different requirements of the promotion area as much as possible. Representatives from the company highly praised the high-yield potential, disease resistance, lodging resistance, resistance to sprouting stress, and strong gluten quality characteristics of the new wheat ice grass line, and expressed strong willingness for the next step of cooperative development and promotion.

I followed the Pubing series for 3 years and tried planting for 2 years, especially during the 'rotten field rain' last year. We saw that the Pubing 300 variety is very resistant to sprouting and can reach a thousand grain weight of 42 to 43 grams, "said Li Songke, Chairman of Henan Kelin Seed Industry Co., Ltd." I noticed that the ear layer of Pubing series wheat is relatively thick, with three layers of ears, especially the bottom spikelet, which I counted to be around 15 grains, and its maturity period is very close to that of the top spikelet. This means that the spikelet can also produce grain, which can increase yield and has great production potential. We are planting in the base for the second year this year, every year. After planting one acre of land, the number of grains per ear is still very high. Therefore, from a market perspective, we believe that this variety is worth expanding

Give full play to the leading role of the national breeding team

The modernization of agriculture relies on seeds as its foundation. This year is a crucial year for the revitalization of the seed industry, shifting from "laying the foundation in three years" to "seeing results in five years". The Huanghuai wheat production functional zone is the core area of national grain production. Since the revitalization of the seed industry, accelerating the cultivation of breakthrough new sources with original innovation has become a top priority in seed industry technological innovation.

China's wheat breeding began as early as the first half of the 20th century, thanks to the unremitting exploration of generations of breeders, gradually reaching the forefront of the world. Seeds are the "chip" of agriculture, and the advancement of seed industry technology is the foundation of agricultural development and an important prerequisite for ensuring food security.

At present, China's wheat yield level ranks among the top in the world, with obvious advantages in self-sufficiency of independent varieties. However, it also faces problems such as the bottleneck period of yield improvement and insufficient supply of high-quality green and multi resistant varieties. Looking back at the development process of seed industry technology innovation, every large-scale improvement in yield and quality is due to the emergence of breakthrough new germplasm and the derivation of a large number of breakthrough major new varieties. "Ye Yujiang, Vice President of the Chinese Academy of Agricultural Sciences, said that for example, researcher Li Lihui led a team to create a batch of breeders who can use, use and want to use these breakthrough major new varieties based on solving the problem of distant hybridization between wheat and ice grass through more than 30 years of hard work. A new germplasm of wheat with multiple grains per spike, green disease resistance, and high-quality strong gluten, Further expanding the new gene sources for wheat breeding has enhanced the competitiveness of China's wheat seed industry.

Seeds are the foundation of agriculture, while germplasm resources are the cornerstone of the seed industry. The National Crop Germplasm Bank located in Beijing preserves over 50000 wheat germplasm resources in temperatures as low as minus 18 degrees Celsius. These well preserved rich genes are the hope for crop breeding and seed industry revitalization in China. Crop germplasm resources play a significant role in genetic breeding. Chinese agricultural scientists have cultivated many new varieties using crop germplasm resources. After these new varieties are cultivated, farmers plant them, increasing the original yield by 4 to 5 times, or even 8 to 9 times, "said Liu Xu.

In the base of the Crop Research Institute of the Chinese Academy of Agricultural Sciences in Xinxiang, Henan, more than 20 research groups conduct over 60 scientific research tasks here every year, cultivating new varieties for the Huang Huai Hai and surrounding areas, and providing breeding materials for numerous research institutions.

This 1100 acre Xinxiang base has been under construction since 1993 and officially settled in 2003. It is the only comprehensive experimental base in the main wheat producing area of the Huang Huai Hai region, playing an important role in supporting scientific and technological innovation and promoting the transformation of achievements. The base has developed multiple series of new varieties of food crops. "Zhang Jinpeng introduced that" the creation and application of dwarf wheat and its efficient breeding methods "won the first prize of National Science and Technology Progress Award, and" the technology of distant hybridization between wheat and ice grass genus and the creation of new germplasm "won the second prize of National Technical Invention Award. 386 varieties including Zhongmai, Hangmai, Lunxuan, and Pubing series wheat, Zhongdan and Zhongyu series corn, and Zhonghuang series soybeans have been approved by the national and provincial governments, with a cumulative promotion area of over 400 million acres.

The Institute of Crop Science has played a leading role in the national breeding team, "said Zhou Wenbin, director of the Crop Science Research Institute of the Chinese Academy of Agricultural Sciences. The Institute focuses on crops such as wheat, corn, soybeans, rice, and miscellaneous grains, aiming at the forefront of world crop science and technology, facing the needs of modern agricultural development in the country, based on resource research, gene mining as the core, variety cultivation as the goal, and cultivation as the guarantee. It carries out basic and applied research on crop science, providing scientific and technological support for national food security and high-quality agricultural development.

We still need to continue to make efforts in the identification of germplasm resources and promote their transformation and application. We need to strengthen cooperation between science and enterprises, solve the 'last mile' problem from new germplasm to new varieties, continuously accelerate the release and utilization of innovative germplasm, and contribute to the stable production and supply of wheat, "said Zhou Wenbin.

Liu Lihua, Director of the Seed Industry Management Department of the Ministry of Agriculture and Rural Affairs, believes that based on the timely completion of the third national survey of crop germplasm resources, the protection and utilization of germplasm resources should be accelerated through precise identification of resources, improvement and breakthroughs in resource mining and creation, and innovative mechanisms for resource sharing and utilization. Resource advantages should be transformed into innovative and industrial advantages, so that resources can be used effectively and truly play their role.