Increased Production of α-Linolenic Acid in Soybean Seeds by Overexpression of Lesquerella

Soybean is a major crop that is used as a source of vegetable oil for human use. To develop transgenic soybean with high α-linolenic acid (ALA; 18:3) content, the gene isolated from lesquerella () was used to construct vectors with two different seed-specific promoters, soybean β-conglycinin (Pβ-con) and kidney bean phaseolin (Pphas), and one constitutive cauliflower mosaic virus 35S promoter (P35S). The corresponding vectors were used for -mediated transformation of imbibed mature half seeds. The transformation efficiency was approximately 2%, 1%, and 3% and 21, 7, and 17 transgenic plants were produced, respectively. T-DNA insertion and expression of the transgene were confirmed from most of the transgenic plants by polymerase chain reaction (PCR), quantitative real-time PCR (qPCR), reverse transcription PCR (RT-PCR), and Southern blot analysis. The fatty acid composition of soybean seeds was analyzed by gas chromatography. The 18:3 content in the transgenic generation T seeds was increased 7-fold in Pβ-con:, 4-fold in Pphas : , and 1.6-fold in P35S: compared to the 18:3 content in soybean "Kwangankong". The increased content of 18:3 in the Pβ-con: soybean (T) resulted in a 52.6% increase in total fatty acids, with a larger decrease in 18:1 content than 18:2 content. The increase in 18:3 content was also maintained and reached 42% in the Pphas : transgenic generation T. Investigations of the agronomic traits of 12 Pβ-con: transgenic lines (T) revealed that plant height, number of branches, nodes, pods, total seeds, and total seed weight were significantly higher in several transgenic lines than those in non-transgenic soybean. Especially, an increase in seed size was observed upon expression of the gene with the β-conglycinin promoter, and 6%-14% higher seed lengths were measured from the transgenic lines.