Keep China's rice bowl secure! Chinese scientists have made important discoveries

"High yield " and " early maturity " are contradictory words in traditional agricultural production.

Because the prerequisite for achieving high yield is to have a certain biomass, and a certain biomass must have a certain growth cycle. A short growth cycle means a small biomass. Therefore, under normal conditions, high yield and growth period are negatively correlated. Crops with short growth periods and early maturity have low yields, while crops with long growth periods have high yields.

In July 2022, Chinese scientists published a study in the international academic journal Science that discovered the high-yield rice gene OsDREB1C, which broke this contradiction . So, why can the gene OsDREB1C break the traditional agricultural production of "high yield but not early maturity, early maturity but not high yield" and allow rice to achieve both high yield and early maturity?

01

Factors affecting rice yield

To uncover the secret of how the gene OsDREB1C enables high rice yield, we might as well first understand the factors that affect rice yield.

The main source of rice yield is photosynthetic products, which absorb light energy through chlorophyll in the leaves, synthesize carbon dioxide and water into organic matter, and then transport it to other parts of the plant . In the early stage of plant growth, photosynthetic products mainly provide protein and energy required for plant growth. After flowering, the plant enters the reproductive growth stage, and the photosynthetic products synthesized in the leaves and stored in the stems are transported to the grains.

Therefore, the formation of yield is inseparable from the organic matter synthesized by photosynthesis, which goes through a series of transportation and is finally stored in the grains.

Image source: provided by the author

Crop yields involve various factors that affect the synthesis, transportation, distribution, and storage of photosynthetic products. Therefore, various factors that affect these processes may cause changes in yield. The newly discovered rice high-yield gene OsDREB1C can affect factors such as photosynthetic product synthesis, which is manifested in improving photosynthesis efficiency and nitrogen utilization efficiency , significantly increasing rice yield.

02

How to achieve high rice yield

Nitrogen is indispensable to plants and is closely related to photosynthesis, affecting its efficiency. At the same time, nitrogen is the main component of protein and plays an important role in the growth of stems and leaves.

If there is not enough nitrogen fertilizer in the soil, or if the plant does not absorb enough nitrogen, its photosynthesis and growth in all aspects will be affected. The gene OsDREB1C is a nitrogen-efficient gene that can make full use of even a small amount of nitrogen in the soil.

In addition, if the utilization efficiency of nitrogen is not high, the large-scale use of nitrogen fertilizers is likely to cause waste, which not only increases farmers' planting costs but also causes environmental pollution. Breeders are committed to exploring nitrogen-efficient genes in breeding to achieve "reducing nitrogen without reducing yields", thereby reducing farmers' planting costs and providing a guarantee for achieving "eco-friendly" high-yield rice.

Image source: provided by the author

03

How to achieve early maturity of rice

The reproductive growth period of rice includes the booting stage, heading and flowering stage, and grain filling and fruiting stage.

The heading and flowering period refers to the period from when the rice ear emerges from the top sword-leaf stem sheath to when it blooms and forms a head, which is generally 5-7 days. The early or late flowering of rice is affected by the gene responsible for regulating florigen , which is a substance equivalent to inducing flowering. The higher its content, the earlier the heading and flowering. The gene OsDREB1C discovered this time is also a florigen regulating gene, which can increase the content of florigen , causing the rice to show early heading, shorten the growth period, and lead to early maturity, thus breaking the contradiction between "high yield" and "early maturity", allowing rice to achieve both high yield and early maturity.

Image source: provided by the author

04

Why is the rice high-yield gene so powerful?

The traits of a plant are formed by the interaction of many genes. One trait has a gene lineup, like a system pathway.

The newly discovered high-yield rice gene OsDREB1C is a transcription factor , which is like a "molecular switch". At the top of this pathway, there are many genes that control photosynthesis, nitrogen absorption and utilization, and flowering. When the expression level of this gene increases, the downstream photosynthesis genes, nitrogen absorption and efficient utilization genes, and genes affecting the heading period are activated through the gene regulation network , thereby coordinately regulating the photosynthetic efficiency, nitrogen utilization efficiency and heading period of rice.

Image source: provided by the author

05

How to promote the application?

The discovery of high-yield genes is a prerequisite for high-yield breeding, but whether the gene OsDREB1C can finally be used in high-yield breeding still requires overcoming many difficulties.

Breeding requires the creation of parental materials. Rice with this gene can be used as a donor through hybridization with the main varieties in different regions . Introducing the OsDREB1C gene into different variety backgrounds can, on the one hand, verify its yield-increasing effect in different variety backgrounds, and on the other hand, create high-yield materials that are suitable for different ecological zones.

Or it can be achieved through gene editing. If gene editing is successful, it may be the closest to application. If the expression of this gene is increased by gene editing, even if it is half the effect, the help it will generate in breeding will be considerable.

The discovery of the high-yield rice gene has broken the long-standing contradiction between "high yield" and "early maturity" in agricultural production. At the same time, it also has great application prospects in different crops, which will provide support for the revitalization of the seed industry and contribute to ensuring national food security and protecting the environment.

"Every meal should be appreciated as it is not easy to come by." Yesterday was World Food Day . Let us thank the scientists who have worked hard for our country's food security. Let us also always remember to save food and avoid waste .

Produced by | Science Popularization China

Author｜Guo Rongyu Yuqing Beijing Keying Art Forest Team

Review | Xu Jianlong, Second-level Researcher, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences

Producer｜China Science Expo

Submitted by: Computer Information Network Center, Chinese Academy of Sciences

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