Determining genetic markers and seed characteristics related to high test weight in Glycine max

Authors: SHEA, ZACHARY - Virginia Tech; SINGER, WILLIAM - Virginia Tech; RSSO, LUCIANA - Virginia Tech; Song, Qijian; ZHANG, BO - Virginia Tech

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2023
Publication Date: 8/19/2023
Citation: Shea, Z., Singer, W., Rsso, L., Song, Q., Zhang, B. 2023. Determining genetic markers and seed characteristics related to high test weight in Glycine max. Plants. 12(16). Article e2997. https://doi.org/10.3390/plants12162997.
DOI: https://doi.org/10.3390/plants12162997

Interpretive Summary: Soybean is the most important protein and oilseed crop due to its low production cost and wide variety of uses in feed, food and biofuel. Test weight is a measure of the number of kilograms in one hectoliter of soybean seeds, and is the most important indicator of soybean seed quality, because soybeans with higher bulk density have a longer storage time, higher seed integrity, and less moldy. Over the past 50 years, soybean growers have observed a downward trend in test weight and noticed lost profits. Despite the importance of test weight, very limited work has been done on this trait. Researchers at Virginia Tech and USDA-ARS evaluated a large number of diverse southern soybean germplasms for the trait variation and identified accessions with high test weights, they also identified molecular markers significantly associated with the trait. New germplasm and molecular markers from this research will help breeders efficiently select lines from breeding programs and develop soybean varieties with increased test weight to ensure long-term profitability for growers.

Technical Abstract: Test weight, one of the primary indicators of soybean seed quality, is measured as the amount of soybean seeds in kilograms that can fit into one hectoliter. The price that growers receive for their soybean is dependent on test weight. Over the past 50 years, growers have observed a decreasing trend in test weight. Therefore, it is imperative to better understand the relationship between soybean test weight and other traits to enable breeders to select parents with high test weight in breeding programs to ensure the grower’s profitability. The objectives of the study were to identify genetic markers associated with high test weight in soybean and to determine the correlation between high test weight and five important seed composition traits (protein, oil, sucrose, raffinose, and stachyose content). Maturity group IV and V germplasms from the USDA soybean germplasm collection were grown in Blacksburg and Warsaw Virginia from 2019 to 2021 and were measured for the traits. Results show that test weight values ranged from 62-77 kg/hL over the three years. Multiple single nucleotide polymorphisms (SNPs) significantly associated with high test weight were found on chromosome 15, and eight candidate genes were found near these SNPs. Test weight was found to be significantly negatively correlated with oil content, inconsistently correlated with protein content in all environments, and negatively correlated but not significantly with all three sugars except for raffinose in Blacksburg 2019. We concluded that the genes that underlying test weight might be on chromosome 15, and the validated associated SNPs might be used to assist breeding selection of test weight. Breeders should pay special attention to test weight while selecting high-oil soybean due to their negative correlation.