Switch for improving nitrogen use efficiency in rice has been found

Science and Technology Daily News (Reporter Zhang Ye, Correspondent Zhao Yeye) The research group of Professor Xu Guohua at Nanjing Agricultural University has recently discovered in rice a nitrate transport protein regulated by cellular pH. Overexpression of this gene can promote the uptake of more nitrogen from the soil by rice, improving rice yield and nitrogen use efficiency. The related research results were recently published in the Proceedings of the National Academy of Sciences (PNAS).

Rice is a major food crop, feeding nearly 50% of the world's population. High rice yields cannot be achieved without the application of nitrogen fertilizer, but at present the average nitrogen use efficiency of rice in China is only 35%. In order to increase rice yields, large amounts of nitrogen fertilizer have to be used, which not only wastes resources and energy, but also exacerbates a series of ecological and 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 itself at the source through breeding.

According to Xu Guohua, rice can grow in both flooded and dry cultivation environments. Flooded anaerobic conditions favor the accumulation of ammonium salts in the soil, while dry cultivation and the release of oxygen from rice roots can promote the utilization of nitrate. Soil ammonium and nitrate nutrition affect the acid-base balance of plant cytoplasm, thereby affecting cell metabolism and plant growth.

They discovered in rice a gene encoding a nitrate transport protein. After overexpression of this gene in plant cells, it can better buffer pH changes in the cells, thereby facilitating the uptake of more nitrogen as well as nutrients such as iron and phosphorus. Field trials showed that this method can increase rice (Nipponbare) yield by 20%-54% and improve nitrogen use efficiency by about 40%.

This research was led by Nanjing Agricultural University, with Dr. Fan Xiaorong as the first author and Xu Guohua and Tony Miller as co-corresponding authors. This research is of great significance for reducing nitrogen fertilizer input in rice and improving the ecological environment, and has already obtained patents in China and the United States, and has been licensed to relevant domestic institutions and international seed companies to breed new crop varieties with high nitrogen efficiency.