Expression of the Arabidopsis WRINKLED 1 transcription factor leads to higher accumulation of palmitate in soybean seed

Abstract

Summary Soybean ( Glycine max [L.] Merr.) is a commodity crop highly valued for its protein and oil content. The high percentage of polyunsaturated fatty acids in soybean oil results in low oxidative stability, which is a key parameter for usage in baking, high temperature frying applications, and affects shelf life of packaged products containing soybean oil. Introduction of a seed‐specific expression cassette carrying the Arabidopsis transcription factor WRINKLED 1 (At WRI 1) into soybean, led to seed oil with levels of palmitate up to approximately 20%. Stacking of the At WRI 1 transgenic allele with a transgenic locus harbouring the mangosteen steroyl‐ ACP thioesterase (GmFatA) resulted in oil with total saturates up to 30%. The creation of a triple stack in soybean, wherein the At WRI 1 and GmFatA alleles were combined with a FAD 2‐1 silencing allele led to the synthesis of an oil with 28% saturates and approximately 60% oleate. Constructs were then assembled that carry a dual FAD 2‐1 silencing element/GmFatA expression cassette, alone or combined with an At WRI 1 cassette. These plasmids are designated pPTN 1289 and pPTN 1301, respectively. Transgenic events carrying the T‐ DNA of pPTN 1289 displayed an oil with stearate levels between 18% and 25%, and oleate in the upper 60%, with reduced palmitate (<5%). While soybean events harboring transgenic alleles of pPTN 1301 had similar levels of stearic and oleate levels as that of the pPTRN 1289 events, but with levels of palmitate closer to wild type. The modified fatty acid composition results in an oil with higher oxidative stability, and functionality attributes for end use in baking applications.

Soybean AP2-Domain Transcription Factor GmWRI4 Optimize Ratio of Oleic Acid to Linoleic Acid in Seed

“…WRINKLED1 (WRI1), an APETALA2 (AP2)-type transcription factor, has been shown to be required for the regulation of carbon partitioning into fatty acid synthesis in plant seeds (Cernac and Benning, 2004). In 2018, the introduction of Arabidopsis transcription factor WRINKLED1 (AtWRI1) into soybean plant, led to seed oil with levels of palmitate up to approximately 20% (Vogel et al, 2019). In another study consider that the close correlation between WRI1 and Stearoy-Acyl-Carrier-Protein Desaturase (SAD) expression suggests the regulatory role of WRI1 in oleic acid accumulation (An and Suh, 2015).…”

“…For example, overexpression of the maize ZmWRI1 expressed under the embryo preferred OLE promoter increased fatty acid content in maize kernels (X. . In addition, Introduction of a seedspeci c expression cassette carrying the Arabidopsis transcription factor WRINKLED1 (AtWRI1) into soybean, led to seed oil with levels of palmitic acid up to approximately 20% (Vogel et al, 2019). Clearly WRI1 acts as a key regulator of oil biosynthesis, which when expression is perturbed, translates to changes in different kinds of fatty acids accumulation (Chen et al, 2018;Kong and Ma, 2018).…”

Lipid metabolism and accumulation in oilseed crops

“…Approximate fatty acid composition of TAGs from selected oilseeds. The values are presented as % of total fatty acids (TFAs) and the given ranges represent the data from diverse literature sources (soybean: Kanai et al, 2019;Vogel et al, 2019;rapeseed: Baud and Lepiniec, 2010;Lu et al, 2020;Arabidopsis: Li et al, 2006;Kelly, 2018;Camelina: Ciurescu et al, 2016;Ozseyhan et al, 2018) Jojoba oil accounts for approximately 60% of the seed weight and contains WEs composed of very long-chain (C20, C22, and C24) monounsaturated FAs and alcohols (Miwa, 1971;Ohlrogge et al, 1978). WEs are synthesised in developing embryos by a three-step pathway, which involves the activity of fatty acid elongase (FAE), fatty acyl reductase (FAR) and wax synthase (WS).…”

“…The Arabidopsis wri1 mutant produced wrinkled seeds with reduced oil content by up to 80% when compared to wild type plants (Focks and Benning, 1998;Cernac and Benning, 2004). In turn, overexpression of AtWRI1 or other WRI1 orthologs elevated oil content in transgenic seeds (Cernac and Benning, 2004;Liu et al, 2010;An and Suh, 2015;Vogel et al, 2019). AtWRI1 regulates the transcription of multiple genes directly involved in glycolytic and FAs biosynthesis pathways such as ACP3, KASI or FAD2.…”

Genome-Wide Association Study Identifies Candidate Genes Related to the Linoleic Acid Content in Soybean Seeds

“…For example, the overexpression of the maize ZmWRI1 expressed under the embryo-preferred OLE promoter increased the fatty acid content of maize kernels [ 27 ]. In addition, the introduction of a seed-specific expression cassette carrying the Arabidopsis transcription factor AtWRI1 into soybean led to seed oil with levels of palmitic acid of up to approximately 20% [ 28 ]. Clearly, WRI1 acts as a key regulator of oil biosynthesis, which, when expression is perturbed, translates to changes in the accumulation of different kinds of fatty acids [ 29 , 30 ].…”