QTL Mapping and Primary Screening of Candidate Genes for Shoot Ureide and Nitrogen Concentration in a Soybean (Glycine Max).

Many studies have reported that shoot ureide and N were highly associated with the sensitivity of N₂ fixation under water-deficit. A 97 F5-derived population from KS4895 x Jackson was used. Shoot ureide and N were measured from R4 to early R5 under irrigated conditions in 3-year field trials. Heritability for shoot ureide and N was 0.73 and 0.60, respectively. Both traits were closely associated (r = 0.72). For shoot ureide, 5 QTLs were identified using composite interval mapping (CIM) on LGs, C2 (1), K (1), F (1), and L (2) with R² values ranging from 0.11 to 0.31 and additive effects ranging from 2.32 to 5.98 uM/g. In multiple interval mapping (MIM), 2 QTLs were coincidently positioned on LGs, F and L. For shoot N, 4 QTLs were detected using CIM on LGs, F (3) and J (1) with R² values ranging from 0.11 to 0.25 and additive effects ranging from 0.085 to 0.156 %. In MIM, one QTL had the same position on LG F as that identified with CIM. All QTLs except for one on LG L would be stable over the years. The QTL on LG F for shoot ureide and N appeared to be pleiotropic considering their overlapping LOD intervals. Identified QTLs for shoot ureide and N were related with traits which were involved in plant growth, seed or yield components and biotic or abiotic stress based on previous QTL information provided by SoyBase. A GO analysis was initially used to search for metabolic-related genes in QTL regions on LGs, F and L in which QTLs were identified with both CIM and MIM analyses. Two notable predicted genes from the Glyma 1.0 gene set were found for shoot N (carbonic anhydrase) and ureide (inosine-uridine nucleoside hydrolase) on LGs, F and L, respectively.