Meta-Analyses of QTLs Associated with Protein and Oil Contents and Compositions in Soybean [Glycine max (L.) Merr.] Seed.

Kyujung Van,Leah K Mchale

doi:10.3390/ijms18061180

Abstract

Soybean [Glycine max (L.) Merr.] is a valuable and nutritious crop in part due to the high protein meal and vegetable oil produced from its seed. Soybean producers desire cultivars with both elevated seed protein and oil concentrations as well as specific amino acid and fatty acid profiles. Numerous studies have identified quantitative trait loci (QTLs) associated with seed composition traits, but validation of these QTLs has rarely been carried out. In this study, we have collected information, including genetic location and additive effects, on each QTL for seed contents of protein and oil, as well as amino acid and fatty acid compositions from over 80 studies. Using BioMercator V. 4.2, a meta-QTL analysis was performed with genetic information comprised of 175 QTLs for protein, 205 QTLs for oil, 156 QTLs for amino acids, and 113 QTLs for fatty acids. A total of 55 meta-QTL for seed composition were detected on 6 out of 20 chromosomes. Meta-QTL possessed narrower confidence intervals than the original QTL and candidate genes were identified within each meta-QTL. These candidate genes elucidate potential natural genetic variation in genes contributing to protein and oil biosynthesis and accumulation, providing meaningful information to further soybean breeding programs.

Highlights

Significant crop improvements have been made internationally, there is still demand for increased food supply and quality [1]
A total of 84 studies were identified (Table S1) which reported a total of 1320 quantitative trait loci (QTL) for protein, oil, amino acids and fatty acids, 648 QTLs with no R2 value and no genetic map information were excluded (Table S2)
A total of 672 QTLs (184 for protein, 212 for oil, 156 for amino acids and 120 for fatty acids) were used in our meta-analyses (Table S2). Of these QTLs, 23 had LOD scores below 2.0, as suggested by Qi et al [24] these were removed and separate meta-QTL analyses were conducted with only “high confidence” QTLs, which consisted of 649 QTLs (175 QTLs for protein, 205 QTLs for oil, 156 QTLs for amino acids and 113 QTLs for fatty acids) with LOD scores > 2.0 (Table S2)

Summary

Introduction

Significant crop improvements have been made internationally, there is still demand for increased food supply and quality [1]. Because soybean seed contains approximately 40% protein and 71% of the world’s meal consumption is reliant on soybean, a percentage which is increasing [4], total protein content has been one of the primary quality traits on which soybean breeding has focused. Both human and animal consumption of soybean is predicted to increase as the demand for plant and animal protein as well as the world population grows [5]. Soybean breeding programs have initiated development of new soybean cultivars which possess essential and balanced amino acid compositions, such as increased levels of cysteine (Cys), methionine (Met), lysine (Lys) and threonine (Thr) [5]

Results

Discussion

Conclusion