Increased Production of α-Linolenic Acid in Soybean Seeds by Overexpression of Lesquerella FAD3-1

Wan Woo Yeom; Hye Jeong Kim; Kyeong-Ryeol Lee; Hyun Suk Cho; Jin-Young Kim; Ho Won Jung; Seon-Woo Oh; Sang Eun Jun; Hyun Uk Kim; Young-Soo Chung

doi:10.3389/fpls.2019.01812

Increased Production of α-Linolenic Acid in Soybean Seeds by Overexpression of Lesquerella FAD3-1

Front Plant Sci. 2020 Jan 31:10:1812. doi: 10.3389/fpls.2019.01812. eCollection 2019.

Authors

Affiliations

¹ Department of Molecular Genetics, College of Natural Resources and Life Science, Dong-A University, Busan, South Korea.
² Department of Agricultural Biotechnology, National Institute of Agricultural Science, Rural Development Administration, Jeonju, South Korea.
³ Biosafety Division, National Institute of Agricultural Science, Rural Development Administration, Jeonju, South Korea.
⁴ Department of Bioindustry and Bioresource Engineering, Plant Engineering Research Institute, Sejong University, Seoul, South Korea.

Abstract

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 FAD3-1 gene isolated from lesquerella (Physaria fendleri) 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 Agrobacterium-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 T₁ seeds was increased 7-fold in Pβ-con:PfFAD3-1, 4-fold in Pphas : PfFAD3-1, and 1.6-fold in P35S:PfFAD3-1 compared to the 18:3 content in soybean "Kwangankong". The increased content of 18:3 in the Pβ-con:PfFAD3-1 soybean (T₁) 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 : PfFAD3-1 transgenic generation T₂. Investigations of the agronomic traits of 12 Pβ-con:PfFAD3-1 transgenic lines (T₁) 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 PfFAD3-1 gene with the β-conglycinin promoter, and 6%-14% higher seed lengths were measured from the transgenic lines.

Keywords: ALA: alpha-linolenic acid; FAME: fatty acid methyl ester; NT: non-transgenic; Pphas: phaseolin promoter; Pβ: β-conglycinin promoter.