Overexpressing Sesamum indicum L.'s DGAT1 increases the seed oil content of transgenic soybean

Soybean (Glycine max) is an important oilseed crop that provides similar to 30% of the vegetable oil used for food, feed and industrial applications. Genetic engineering can produce precise changes in plants in a short period of time and complements conventional plant breeding methods. However, soybean has the lower transformation efficiency and more genotypic limitations than other species, which makes it more difficult to transform. In this study, we introduced diacylglycerolacyl transferase (DGAT) isolated from sesame (Sesamum indicum L.) into the soybean cultivar Dongnong 47, using Agrobacterium-mediated transformation to produce high-oil transgenic lines that are more suitable for breeding. After a 2-year single-location field trial, the transgenic soybean overexpressing SiDGAT1 had increase seed oil content, by an average of over 1.0 percentage point, compared with wild-type plants. Additionally, the transgenic plants expressing SiDGAT1 had significantly reduced protein and soluble sugar contents in mature seeds. SiDGAT1-overexpressing soybean exhibited an altered fatty acid composition, with increases in palmitic (C16:0) and linoleic (C18:2) acid contents and decreases in stearic (C18:0) and oleic (18:1) acid contents, but no major yield change. Thus, engineering the SiDGAT1 enzyme is an effective strategy to improve the oil content and value of soybean.