Written by Yu Feifei and Shen Zhengwei (China Agricultural University).
Recently, Chinese scientists have discovered saline-alkali tolerance genes, and related breeding technologies can significantly improve the yield of sorghum, rice, wheat, corn, millet and other crops in saline-alkali land, so that saline-alkali land can also "rice fragrance"!Let's find out the mystery together!
Crop killer – saline land.
See! This piece of white flowers, is there a feeling of "suspected that it has not been sold through the winter snow"? It's not snow, it's salt from the saline ground. Farmers often say: "If you grow crops in saline-alkali land, you will not harvest them for nine out of ten years." "Saline land is a crop killer.
Saline-alkali land refers to land where the soil contains more soluble salt, which is not conducive to the growth of crops. Specifically, when 100 grams of soluble salt in the soil contains soda salts (sodium carbonate and sodium bicarbonate) at 0More than 5 mg, pH value greater than 9, salt content greater than 03 hours, it belongs to saline-alkali land.
Crop growth needs a relatively stable and suitable external environment, and the high pH value and high permeability soil environment in saline-alkali land will lead to crop yield reduction and even death. This is because a high pH will inhibit the absorption of nutrients such as potassium, phosphorus, and iron by crops, resulting in "malnutrition" of crops; High permeability in the soil causes crops to be unable to absorb water from the soil.
According to the Food and Agriculture Organization of the United Nations, as of 2015, there were more than 1 billion hectares of saline land in the world, and this number is set to grow. The situation of land salinization in China is also severe, and in the past 60 years, the area of saline-alkali land in China has increased from about 240,000 square kilometers has increased to about 40,000 square kilometers, and the degree of salinization is still deepening.
The problem of land salinization has seriously endangered China's food security, and it is urgent to breed saline-alkali tolerant crops, improve the utilization rate of salinized land, and protect national food security.
Locking on "key genes."
Excavation of crop saline-alkali tolerance genes is the key to salinity-alkali tolerance breeding.
We know that the traits of crops are controlled by genes in the body. In the process of adapting to the environment, the genes of crops will be different, and crops will evolve with them.
Sorghum originated in Africa and is one of the earliest grasses cultivated by humans, and it has a stronger salt tolerance than rice and wheat.
We collected more than 300 raw sorghum materials from different regions, planted them in highly salinity soils, and divided them into salinity-tolerant varieties and non-salinity-tolerant varieties according to their growth conditions. Through calculations, it is possible to correlate the genetic differences of different varieties with their tolerance to salinity. From this, we can determine which genes of different traits have been altered, and finally "lock" the AT1 (alkaline tolerance 1) gene.
So, how does the AT1 gene work?
It turns out that when crops are damaged by salinity, cells produce reactive oxygen species (ROS). Reactive oxygen species is a general term for substances composed of oxygen, oxygen-containing and active in the body or natural environment, which can be used as a signal molecule to regulate metabolic reactions such as stomatal closure and disease defense in plants, and play a positive role in crop growth.
However, the biological activity of reactive oxygen species is very strong, and excessive accumulation will destroy the reactive oxygen species balance of crop cells (under normal conditions, the content of reactive oxygen species in plants is not more or less, and it is in a balanced and stable state), affecting the growth and development of crops and reducing crop yields. If you want crops to be more tolerant to salinity, you must maintain the balance of reactive oxygen species in crop cells.
This is where aquaporins come in. Aquaporins are a class of channel proteins on biological membranes with selective, efficient water transport functions and special spatial structures. It can "pump" excess reactive oxygen species from inside the cell to the outside of the cell. However, not all aquaporins have this function, only those that are phosphorylated (a protein modified).
We found that the AT1 gene inhibits phosphorylation of aquaporins. In other words, using gene editing to knock out the AT1 gene can give crops the "ability" to "tolerate" salinity.
Saline-alkali land becomes a high-yield field.
Practice is the only criterion for testing truth, and any experimental results must be tested in production practice. GS3 is a homologous gene of AT1 in rice, and we conducted a two-year GS3 improved rice field production experiment in Da'an saline-alkali land in Northeast Jilin Province, with an annual yield increase of 241%～27.8%。At the same time, in the yield measurement experiments of sorghum, millet, corn and other crops, the yield of sorghum and millet and the survival rate of corn have been greatly improved.
If 20% of the world's saline-alkali land could use this technology, it could increase production by at least about 2500 million tons of grain, saline-alkali land will be turned into a high-yield crop field!
A strong country must first strengthen agriculture, and only when agriculture is strong can the country be strong. "Cultivating saline-tolerant food crops is the top priority to effectively improve the productivity of salinized land and solve the problem of food security. In the near future, the rice, steamed bread, and corn on our tables may come from crops in saline-alkali fields.
Using your knowledge of chemistry and biology, what other ways can you think of to improve saline-alkali soil?
Knowledge LinksWhat are channel proteins?
Ions and some small organic molecules such as glucose, amino acids, etc., cannot freely pass through the cell membrane. Some special proteins embedded in the cell membrane that facilitate the transport of these substances along the concentration gradient across the membrane are called transporters.
Transporters are divided into two types: carrier proteins and channel proteins. Channel proteins include aquaporins and ion channel proteins, among others.
Carrier proteins allow only molecules or ions that are compatible with their binding site to pass through, and they change themselves with each transport.
Channel proteins allow only molecules or ions that are appropriate for the diameter and shape of their channels, and that are appropriate for their size and charge. When a molecule or ion passes through a channel protein, it does not need to bind to the channel protein.
Knowledge is Power" magazine, the original title is "Saline-alkali Tolerance Gene: Let the "Rice Fragrance" in the Saline-alkali Land", the author Yu Feifei and Shen Zhengwei, with deletion and correction, original work**Please indicate**.