Production of γ-Linolenic Acid and Stearidonic Acid in Seeds of Marker-Free Transgenic Soybean

Abstract

and black currents (Ribes nigrum L.) (Goffman and Galletti, 2001). The yield potential of these herbs is Through a single desaturation step, the Borago officinalis L. ⌬ 6 rather limited and levels of GLA and STA in the seed desaturase can convert linoleic acid and ␣-linolenic acid to ␥-linolenic acid (GLA) and stearidonic acid (STA), respectively. Both GLA and storage lipids constitute Ͻ16 and 5%, respectively. STA are of interest to the pharmaceutical and nutraceutical industries.In plants, GLA is produced by the desaturation of Production of these fatty acids is costly. One potential strategy to linoleic acid via a ⌬ 6 desaturase (Sayanova et al., 1997). reduce production cost would be to generate them in a major oilseed A cDNA clone of a ⌬ 6 desaturase from borage excrop. To this end, a cDNA of the B. officinalis ⌬ 6 -desaturase gene pressed in tobacco was capable of generating both GLA was cloned downstream of the embryo-specific promoter ␤-conglyciand STA in the transgenic plants at 12.9 and 8.5%, nin. The resultant cassette was assembled into a two T-DNA binary respectively, in young leaves (Sayanova et al., 1997). vector, in which the second T-DNA element harbored a selectable Accumulation of the novel fatty acids in the transgenic marker cassette. The final plasmid was subsequently used to transform tobacco lines varied across tissue, with the highest levels soybean [Glycine max (L.) Merr.]. The simultaneous delivery of two of 27.2% GLA and 8.7% STA being observed in stem T-DNA elements was used as a strategy to derive soybean progeny transgenic for the ⌬ 6 desaturase T-DNA and free of the marker gene tissue (Sayanova et al., 1999). Introduction of a fungal T-DNA. Twenty-nine transgenic soybean lines were recovered that (Mortierella alpina Peyronel) ⌬ 6 desaturase into canola harbored both T-DNA elements, of which 17 produced GLA and (Brassica napus L.) resulted in accumulation of GLA STA in the seed storage lipids. Average GLA levels ranged from 3.4 in the seed to approximately 13%, while dual expression up to 28.7%, while STA levels varied from just under 0.6 to 4.2% in of the fungal ⌬ 12 -and ⌬ 6 -desaturase genes resulted in the T 1 generation. Among the 17 lines that produced GLA and STA, elevated levels of GLA in seeds, 43%, and production four lines were identified that were free of the selectable marker of STA levels of ≈2% (Liu et al., 2001). The combination T-DNA element.of ⌬ 12 -and ⌬ 6 -desaturase genes was required to enhance GLA levels in canola since the predominate fatty acid in B. napus seed is oleic. Expression of the ⌬ 12 desaturase Univ. of Nebraska, Lincoln, NE 68583; B. Schweiger and A. Kinney, DuPont Exp. Stn., Wilmington, DE 19880. This publication is a contri-nology by implementing the identical marker gene for

Oleaginous crops as integrated production platforms for food, feed, fuel and renewable industrial feedstock

“…Overexpression of Ostreococcus tauri Δ6-desaturase (Domergue et al, 2005) in transgenic camelina resulted in the accumulation of high levels of Δ6-desaturated fatty acids with 18% γ-linolenic acid (18:3 n-6, GLA) and 12% stearidonic acid (18:4 n-3, SDA) (Sayanova et al, 2011). The total level of non-native Δ6-desaturated fatty acids (30% of seed oil) was about twice that achieved using the same construct in Arabidopsis and compared well with previous attempts to synthesize these fatty acids in transgenic soybean (Sato et al, 2004;Eckert et al, 2006) and Brassica juncea (Hong et al, 2002) using phospholipid-dependent Δ6-desaturase activities. The potential of using acyl-CoA-dependent desaturases to enhance LC-PUFA production in camelina seeds was subsequently demonstrated.…”

Enhancing Plant Seed Oils for Human Nutrition

“…Delta-6 desaturase genes from borage, Pythium irregulare, and Saprolegnia diclina have been seed specifically expressed in soybean, Brassicca juncea, and safflower (Carthamus tinctorius), with resulting GLA contents in the seed oil as high as 70% of total fatty acids Qiu et al, 2002;Sato et al, 2004;Knauf et al, 2006). Because most oilseed crops are predominantly omega-6 fatty acid-containing plants, it is necessary to express an omega-3 desaturase gene along with the delta-6 gene to produce SDA.…”

Generation and characterization of herbicide-resistant soybean plants expressing novel phosphinothricin N-acetyltransferase genes

“…The addition of antioxidant reagents such as L-cysteine and dithiothreitol has thus been shown to increase substantially the efficiency of transformation by this approach Somers 2001, Olhoft et al 2003). The bar gene has been widely applied as a selective marker in combination with glufosinate for the transformation of soybean cotyledonary node tissue (Zhang et al 1999, Paz et al 2004, Sato et al 2004, Zeng et al 2004, Paz et al 2006. Yun et al (2009) demonstrated the utility of the mat gene as a selective marker in Arabidopsis transformation and the PPT resistance in transformed rice calli harboring mat.…”