Genome-wide association study identified novel genetic loci controlling internode lengths and plant height in common wheat under different nitrogen treatments

Nitrogen is an important nutrient for crop growth and development. Plant height-related traits can be affected by nitrogen supplementation. In this study, we performed a genome-wide association study (GWAS) on plant height, spike length, length of different internodes, and lodging resistance strength at the grain-filling stage based on wheat local varieties subjected to low nitrogen and normal (CK) treatments. GWAS analysis showed that a total of 86 quantitative trait locus (QTLs) were detected, including 13 QTLs for plant height, 10 QTLs for spike length, 19 QTLs for the length of the first internode from the top of the plant, 6 QTLs for the second internode length, 11 QTLs for the third internode length, 13 QTLs for the fourth internode length, and 14 QTLs for the fifth internode length. Compared to the CK treatment, the plant height, spike length, and fourth and fifth internode lengths were significantly affected by the low nitrogen treatment. A total of 18 QTLs responding to low nitrogen level were detected, including three QTLs for the fourth internode length detected on 3A, 6A, and 6D chromosomes, eleven QTLs for the fifth internode length on 1A, 1B, 1D, 2A, 2B, 3A, 3B, 4A, 5B and 7B chromosomes, one QTL for spike length on 3A chromosome, and one QTL for plant height on 5B chromosome. These QTLs will enhance our understanding of the genetic basis of plant height responses to nitrogen deficiency and will benefit genetic reactions to nitrogen fertilization.