Elemental sulfur concentration can be used as a rapid, reliable, and cost-effective predictor of sulfur amino acid content of soybean seeds

Authors: KIM, WONSEOK - University Of Missouri; KIM, SUNHYUNG - University Of Missouri; MAWHINNEY, THOMAS - University Of Missouri; Krishnan, Hari

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2024
Publication Date: 2/7/2024
Citation: Kim, W., Kim, S., Mawhinney, T.P., Krishnan, H.B. 2024. Elemental sulfur concentration can be used as a rapid, reliable, and cost-effective predictor of sulfur amino acid content of soybean seeds. Scientific Reports. 14. Article 3093. https://doi.org/10.1038/s41598-024-53590-3.
DOI: https://doi.org/10.1038/s41598-024-53590-3

Interpretive Summary: Soybean is an excellent source of protein for both humans and livestock. However, the nutritional quality of soybean protein remains suboptimal due to lower concentrations of sulfur-containing amino acids cysteine and methionine. Increasing the sulfur amino acid content in soybean has been a critical goal for breeders to achieve. Currently, methods used to quantify these amino acids in soybean are time-consuming and cost-prohibitive. In this study, we have examined if the elemental sulfur content can be used as an alternative for rapid and reliable method to predict the sulfur amino acid content of soybean seed. Our results indicate that elemental sulfur content of soybean seed can be used as a proxy to rapidly identify soybean lines with relatively higher sulfur amino acid content. This trait is important for improving the nutritional quality and health benefits of US soybean products. Our procedure can be exploited by soybean breeders to develop elite’s soybean lines with desirable amino acid composition.

Technical Abstract: In this study, we have examined the feasibility of using elemental sulfur content of soybean seeds as a proxy for the overall sulfur amino acid content of soybean seeds. Earlier, we have identified by high throughput ionomic phenotyping several high and low sulfur containing soybean lines from the USDA Soybean Germplasm Collection. Here, we measured the cysteine and methionine content of select soybean lines by high-performance liquid chromatography (HPLC). Our results demonstrate that those soybean lines which had high elemental sulfur content also had a higher cysteine and methionine content when compared to soybean lines with low elemental sulfur. SDS-PAGE and immunoblot analysis revealed that the accumulation of Bowman Birk protease inhibitor and lunasin in soybean seeds may only be marginally correlated with the elemental sulfur levels. However, we found a positive correlation between the levels of trypsin and chymotrypsin inhibitor activities and elemental sulfur and sulfur amino acid content of the seeds. Thus, elemental sulfur content and/or protease inhibitor activity measurement can be utilized as a rapid and cost-effective method to predict the overall sulfur amino acid content of soybean seeds. Our findings will benefit breeders in their endeavors to develop soybean cultivars with enhanced sulfur amino acid content.