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Abstract
Soybean seed composition plays an important role in the utility of soybean, especially the use of high protein meal. Improving the seed composition of soybean without negatively affecting yield and oil content is one of important goals to soybean breeders. However, the negative relationships of protein content with yield, oil, and sucrose contents have complicated the genetic improvement of soybean seed composition. Studies have shown that it is possible to improve seed composition even though these negative effects. An RIL population was developed between an elite breeding line, G00-3213 and a plant introduction, PI 594458A with desirable seed composition profile. In 2016 and 2017, single rows were grown in Watkinsville, GA, while in 2018 the population was grown at two locations with two replications per location. The RIL population was phenotyped with NIR. The high and normal protein bulks were formed based on 2017 data and genotyped along with the parents with SoySNP50k iSelect BeadChip and the RIL population was genotyped using the SoySNP6k iSelect BeadChip to perform QTL analysis for important seed composition traits. Bulked segregant analysis (BSA) identified significant genomic regions on chromosomes 3, 5, 6, 10, 11, and 13 for elevated protein content, while regions for elevated sucrose contents were identified on chromosomes 9 and 13. QTL analysis of data using whole genome markers from 4 environments identified 21 QTLs for protein, 13 for oil, 9 for sucrose, 4 for cysteine, and 13 for methionine. QTLs identified on chromosome 5, 6, and 13 for protein and 9 for sucrose were consistent with the BSA results. QTLs for protein identified on chromosome 6, 13, and 15 were detected in two of four tested environments, and a segment on chromosome 10 for methionine content was detected in all but one environment. The results of this research can provide additional genomic resources for genetic improvement of seed composition and help us to better understand the impacts of environment on these QTLs.