Date of Graduation

12-2020

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Mozzoni, Leandro A.

Committee Member

Hettiarachchy, Navam S.

Second Committee Member

Chen, Pengyin

Third Committee Member

Brye, Kristofor R.

Keywords

Association; Genetics; Mapping; Oil; Protein; Soybean

Abstract

Soybean [Glycine Max (L.) Merrill] is an important economic crop because of its high content of seed protein and oil. Seed oil and protein content are quantitative inherited traits. The genetics of seed protein and oil levels have been extensively studied, with 367 QTL reported for protein and 475 QTL reported for oil to date. Validation of such QTLs, and identification of easily-automatable molecular markers around these QTL will aid the progression of breeding for such traits. The focus of this research was to discover novel and verify previously reported QTL related to protein and/or oil content via Genome-Wide Association Study (GWAS). A total of 391 Plant Introduction (PI) lines from the Germplasm Resource Information Network (GRIN) database were used, representing contrasting seed protein and oil content. A single-row plot with one replication was grown in 3-meter rows in Fayetteville, AR in 2015, and with two replications in Fayetteville, AR, Stuttgart, AR, and Raleigh, NC in 2016 in a randomized-complete block design. Seed samples were assessed for protein and oil concentration using the Perten DA 7250™ NIR analyzer. To perform the GWAS and detect QTL controlling both protein and oil content in soybean, the resulting seed content phenotypic data was utilized in conjunction with publicly available SoySNP50k iSelect BeadChip database from the USDA-ARS Soybean Germplasm Collection. We detected significant markers previously reported for seed protein content on chromosome 5, 7, 9, 18, and 20, and on chromosomes 7, 8, 13, 15, 19, and 20 for seed oil content. In addition, we reported new QTL for seed protein on chromosomes 8, 10, 15, 16, and 20, and for oil on chromosomes 5, 7, 8, and 18. Future QTL mapping via use of bi-parental populations will be necessary to confirm QTL and validate the genes identified as novel in this study.

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