Profiling seed soluble sugar compositions in 1164 Chinese soybean accessions from major growing ecoregions

Soluble sugar is a key quality trait of soybean seeds. We developed rapid and economic extraction and quantification methods for seed soluble sugars using an ultra-high performance liquid chromatography system with a refractive index detector. We evaluated the soluble sugar compositions of 1164 soybean accessions collected from diverse ecoregions and grown in multiple locations and years. Total soluble sugar (TSS) content was influenced by accession type, year of cultivation, and ecoregion. The mean contents of fructose, glucose, sucrose, raffinose, stachyose and TSS were 3.31, 5.21, 55.60, 6.60, 35.47, and 106.19 mg g⁻¹, respectively. The highest mean TSS content (108.71 mg g⁻¹) was observed in accessions from Northern Region of China. Cultivars contained higher contents of sucrose, raffinose, and TSS, whereas landraces had a higher content of stachyose. Fourteen accessions with mean TSS contents > 130 mg g⁻¹ were identified as elite soybean resources. TSS was correlated with sucrose, raffinose, stachyose, protein, oil and total tocopherol. The main soluble sugar components were correlated with latitude and longitude, indicating that the geographical origin of the accessions affected their seed soluble sugar compositions. The developed methods and elite identified accessions can be used in the food and feed industry and in soybean breeding programs aimed at improving soybean seed nutrition.