GmSWEET46 Regulates Seed Oil and Protein Content in Soybean

Seed oil and protein contents are critical agronomic traits that determine soybean quality. However, the key loci and corresponding genes controlling these quality traits remain to be elucidated. Here, we performed bulked segregant analysis by sequencing (BSA-seq) using an F4 population derived from a cross between the cultivars Heinong 35 (HN35) and Dengke 3 (DK3). A major soybean oil and protein quantitative trait locus (QTL) designated as q-OP18 was identified on chromosome 18, and the sugar transporter gene GmSWEET46 was further cloned. Haplotype analysis revealed that a single-nucleotide polymorphism (SNP) in the sixth exon of GmSWEET46 results in an amino acid change between HN35 and DK3 and is associated with seed oil and protein content, suggesting its important role in determining seed quality in soybean. GmSWEET46 is expressed during the early stages of seed and pod development and localizes to the plasma membrane, indicating its potential function as a sugar transporter. Further studies demonstrated that GmSWEET46 can regulate seed protein content, oil content, and seed size in Arabidopsis and soybean. Collectively, this study provides a novel locus and gene for regulating soybean seed traits and offers valuable resources for the breeding of high-quality and high-yielding soybean cultivars.