Seed specifically overexpressing SiDGAT1 enhances seed oil contents in soybean

Diacylglycerol acyltransferase (DGAT) is a rate-limiting enzyme in the Kennedy pathway that catalyzes the final committed step of triacylglycerol (TAG) biosynthesis, making it a pivotal target for improving seed oil content in oilseed crops. A transgenic soybean line, KNPROE1, was developed by seed-specific overexpression of the SiDGAT1 gene driven by the soybean GmOLE8 promoter. This transformation was achieved via Agrobacterium-mediated methods, using the cultivar 'KenNong 18' (KN18) as the recipient. Molecular analyses including PCR, Southern blot, Western blot, and flanking genomic sequencing confirmed that KNPROE1 harbors a stable, single-copy T-DNA insertion located in a non-coding intergenic region on chromosome 13, ensuring no disruption of endogenous genes. Event-specific PCR further validated the unique insertion site. RT-qPCR and enzyme-linked immunosorbent assay (ELISA) demonstrated preferential expression of SiDGAT1 in seeds, peaking at full maturity (R8 stage). The expression of the transgenes and the efficacy of glyphosate tolerance were stable. Moreover, a two-year field evaluations demonstrated that KNPROE1 consistently increased seed oil content by 1.71% to 4.48% across T₃ and T₄ generations without compromising seed protein content. While slight variations in plant height, main stem node number, and 100-seed weight were noted, major yield-related traits, including pod number and seed number per plant were not significantly affected. These findings establish that KNPROE1 is a genetically stable and agronomically viable germplasm resource for breeding high-oil soybean cultivars.

The online version contains supplementary material available at https://doi.org/10.1007/s11032-026-01738-6.