Improved oil quality in transgenic soybean seeds by RNAi-mediated knockdown of GmFAD2-1B
Soybean oil contains approximately 20% oleic acid and 63% polyunsaturated fatty acids, which limits its uses in food products and industrial applications because of its poor oxidative stability. Increasing the oleic acid content in soybean seeds provides improved oxidative stability and is also beneficial to human health. Endoplasmic reticulum-associated delta-12 fatty acid desaturase 2 (FAD2) is the key enzyme responsible for converting oleic acid (18:1) precursors to linoleic acid (18:2) in the lipid biosynthetic pathway. In this study, a 390-bp conserved sequence of GmFAD2-1B was used to trigger a fragment of RNAi-mediated gene knockdown, and a seed-specific promoter of the β-conglycinin alpha subunit gene was employed to downregulate the expression of this gene in soybean seeds to increase the oleic acid content. PCR and Southern blot analysis showed that the T-DNA had inserted into the soybean genome and was stably inherited by the progeny. In addition, the expression analysis indicated that GmFAD2-1B was significantly downregulated in the seeds by RNAi-mediated post-transcription gene knockdown driven by the seed-specific promoter. The oleic acid content significantly increased from 20 to ~ 80% in the transgenic seeds, and the linoleic and linolenic acid content decreased concomitantly in the transgenic lines compared with that in the wild types. The fatty acid profiles also exhibited steady changes in three consecutive generations. However, the total protein and oil contents and agronomic traits of the transgenic lines did not show a significant difference compared with the wild types.
KeywordsSoybean RNAi-mediated gene knockdown Fatty acid profile Oleic acid
This work was supported by grants from the China National Novel Transgenic Organisms Breeding Project (2016ZX08004-003), National Natural Science Foundation of China (31671764), and Jilin Provincial Agricultural Science and Technology Innovation Project in China (CXGC2017JQ013).
JY performed the PCR, Southern blot and fatty acid profile analysis; GX performed the soybean transformation; LN and HH constructed the RNAi vector and analyzed the expression pattern and protein and fat contents; DG and QD designed the primers for PCR and analyzed the agronomic traits of the transgenic and control plants; XQ and YY performed the LibertyLink strip test; HL checked the manuscript. XZ and XY are co-corresponding authors. All authors have read and approved the final version of the manuscript.
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