Date of Award
Doctor of Philosophy
Plant, Soil and Environmental Sciences
Carl E. Sams, Liesel Schneider, Dennis West
Soybean [Glycine max (L.) Merr.] is the world’s leading source of vegetable oil and high quality protein meal. However, soybean protein and oil and protein and yield are negatively genetically correlated. Agronomic and seed quality traits of soybean lines are important because they lead to increased soybean value. Molecular markers have played and will continue to play a major role in the genetic characterization and improvement of soybeans. Quantitative trait loci (QTL) are regions within a genome that contain genes that influence particular quantitative traits. Identification of QTLs through phenotypic evaluation only is not possible; therefore, to locate, identify, and characterize these regions within a genome, DNA or molecular markers are used. A major objective in soybean breeding is to develop high yielding cultivars. Unfortunately, soybean seed yield, as well as protein and oil content, are complex quantitative traits to characterize from the phenotypic and genotypic perspectives. The objectives of this study are to detect soybean genomic regions that increase protein content, while maintaining oil content and seed yield, and to successfully identify soybean QTL associated with these seed quality traits. To achieve these objectives, a population of 138 F8:10 [eighth filial generation advanced to the tenth filial generation] and 138 F8:11 [eighth filial generation advanced to the eleventh filial generation] recombinant inbred lines (RIL) of soybean were created from a cross between 5601T and U99-310255. These RILs were grown in a replicated six environment field trial across the state of Tennessee in the 2017 and 2018 field seasons. Data from the 138 RIL were used to perform QTL detection analyses in search of significant genomic regions affecting soybean seed protein, oil, and yield. A total of 21 QTL were successfully identified through QTL analysis of the population. Of these, there were three for yield, two for protein, five for oil, one for methionine, two for threonine, five for maturity, one for lodging, and two for meal. Knowledge of their locations and flanking markers will aid in marker assisted selection for plant breeders. This will lead to a more valuable soybean for farmers, processors, and animal nutritionists.
Cunicelli, Mia Justina, "Mapping and Identification of QTL Associated with Soybean Seed Protein, Oil, and Yield in 5601T × U99-310255 RIL Population Using SNP Genotyping. " PhD diss., University of Tennessee, 2020.