Molecular basis of the high nitrogen use efficiency of a wheat variety

A research team led by Prof. Ling Hongqing from the Institute of Genetics and Developmental Biology (IGDB) of the Chinese Academy of Sciences (CAS), together with collaborators from Ludong University and the Computer Network Information Center of the CAS, obtained a high-quality genome from Kenong 9204 (KN9204), a high nitrogen use efficiency (NUE) wheat cultivar bred at IGDB, and illustrated its possible molecular mechanisms driving the high NUE through comparative genomic analysis. The results were published on molecular plant on July 21st.

Nitrogen (N) deficiency is one of the most limiting factors in crop production, and about 60% of fertilizer used in agriculture each year is nitrogen fertilizer. The increasing use of N-fertilizers in agriculture has improved yields but also caused serious environmental problems such as water eutrophication and soil acidification. Common wheat (Triticum aestivum L.) is a global staple crop grown on more land than any other food crop. Therefore, improving the N utilization efficiency of wheat is very important for sustaining agriculture and protecting the environment.

In this study, researchers sequenced and assembled the genome of KN9204 and compared it to other known grass genomes. They found that the high-affinity nitrate transporter (NRT2) gene family expanded during wheat evolution. Further analysis confirmed that some of the extended family members acquired new functions, such as B. Response to high salt stress.

Furthermore, they found that nitrate efflux transporter genes, which function in nitrate efflux in the root pericycle and loading of nitrate into the xylem sap, expanded during wildemmer formation. These results could provide a genetic basis for the broad adaptability of wheat to nitrogen deficiency in different geographic and soil environments.

Using transcriptome and gene coexpression network analysis, the researchers identified additional key developmental stages and associated key metabolic pathways of wheat in response to nitrogen deficiency. They found that nitrogen deficiency significantly suppressed the expression of cell division-related genes in young ears of low-NUE wheat cultivar Jing 411, but had a very weak effect on these genes in KN9204.

Combining gene expression with nitrogen accumulation data, they showed that KN9204 had a higher NUE than common wheat varieties, particularly at the stage of reproductive development. Finally, the researchers concluded that the high NUE of KN9204 is an integrated effect that is controlled at different levels, such as: B. Robust and large root systems, high expression of genes related to root development, nitrate uptake and transport.

This study provides new insights into the molecular mechanisms underlying high NUE in wheat and valuable genomic resources for the creation of high NUE wheat cultivars. In addition, the short arm of rye 1RS chromosome carried by KN9204 is an important material for studying wheat diseases and stress resistance.