Find the switch to improve the nitrogen use efficiency of rice

Science and Technology Daily (Reporter Zhang Ye correspondent Zhao Ye) Professor Xu Guohua of Nanjing Agricultural University recently found a nitrate transport protein regulated by cellular pH in rice. Overexpression of this gene can promote rice to absorb more nitrogen from the soil and improve rice yield and nitrogen use efficiency. The results were published in the Proceedings of the National Academy of Sciences.

Rice is a major food crop, feeding nearly 50% of the world's population. The high yield of rice is inseparable from the application of nitrogen fertilizer, but at present, the average nitrogen use efficiency of rice in China is only 35%. In order to improve rice yield, a large number of nitrogen fertilizers have to be used, which not only wastes resources and energy, but also aggravates a series of eco-environmental problems, such as soil acidification, water eutrophication and agricultural greenhouse gas emissions. Therefore, there is an urgent need to improve the nitrogen use efficiency of rice from the source of breeding.

According to Xu Guohua, rice can grow in both flooded and dry farming environments. Flooding and anaerobic conditions are beneficial to the accumulation of ammonium salt in soil, while dry farming and oxygen secretion from rice roots can promote the utilization of nitrate. Soil ammonium nitrate nutrition affects the pH balance of plant cytoplasm, which in turn affects cell metabolism and plant growth.

They found a gene that encodes a nitrate transporter in rice. Overexpression of this gene in plant cells can better buffer the changes of pH in plant cells, which is conducive to the absorption of more nitrogen, iron and phosphorus and other nutrient elements. Field experiments show that the yield of rice (Nipponia) can be increased by 20%, 54%, and nitrogen use efficiency can be increased by about 40%.

The study was led by Nanjing Agricultural University, with Dr. Fan Xiaorong as the lead author and Xu Guohua and Tony Miller as the co-authors. This study is of great significance to reduce the input of nitrogen fertilizer in rice and improve the ecological environment, and has obtained patents in China and the United States, and granted permission to relevant domestic units and international seed companies to cultivate new crop varieties with high nitrogen efficiency.