A Genome-Wide Association Study of Nitrogen Use Efficiency in Rapeseed (Brassica napus)

Nitrogen (N) is the most important mineral nutrient for plant growth. However, production of N fertilizers is energy intensive. Furthermore, there is serious concern regarding nitrogen loss in the field, giving rise to soil and water pollution. Rapeseed (Brassica. napus) is fond of nitrogen while with low N use efficiency (NUE), and a lot of N fertilizer is generally applied in rapeseed production. Therefore, development of rapeseed cultivars with high NUE  is needed. In our previous study, we have analyzed 600 rapeseed lines by a 60 K SNP array, and have proved that the genome-wide association study (GWAS) is an available and rapid approach for fine mapping of complex traits. In this study, we selected 300 lines out of the above-mentioned lines, and investigated their leaf area and biomass of root and shoot under high and low N supply at seedling stage, followed by performing GWAS. As results, four genomic regions were detected to be associated with the dry shoot weight under low nitrogen supply in this study, and some genes involved in N assimilation were identified close to these regions.