Fatty acids transgenic oils

Facciotti, D. Metz, J.G. Lassner, M. (1998) Polyketide synthesis graes of marine microbe and production of polyunsaturated fatty acids and PUFA-containing plant oils with transgenic plants. PCT Int. Appl. 10 Dec. to Calgene LLC Co) Chem. Abstr., 1999,130, 62050. 

Figure 25.1. Proposed biosynthetic pathway of castor oil. Heavy arrows show the key enzyme steps driving ricinoleate into acylglycerols. Two arrows with solid bars show a complete block. Two dashed arrows show the phospholipase C hydrolysis which can be targeted to block the incorporation of non-hydroxyl fatty acids into triacylglycerols to increase presumably the content of ricinoleate in transgenic seed oils.

Fig. 11. Genetic engineering of rapeseed oil. A high level of lauric acid was achieved by expressing a medium-chain acyl-ACP thioesterase (MCTE) from California Bay in the transgenic seeds. This enzyme intercepts the fatty acid synthesis pathway at 12 carbons and hydrolyzes the fatty acid from its ACP carrier. MoI% of major fatty acids in a typical canola cultivar are compared to the composition achieved through genetic engineering.

Gaboon, E.B. T.J. Carlson K.G. Ripp B.J. Schweiger G.A. Cook S.E. Hall A.J. Kinney. Biosynthetic origin of conjugated double bonds Production of fatty acid components of high-value drying oils in transgenic soybean embryos. P. Natl Acad. Sci. USA 1999, 96, 12935—12940. 

Comparison of Novel Fatty Acid Content in Seed Oils of Native Species and Transgenic Species Expressing Primary Biosynthetic Genes from Native Species... 

Lu, C., Fulda, M., Wallis, J.G., and Browse, J. A high-throughput screen for genes from castor that boost hydroxy fatty acid accumulation in seed oils of transgenic Arabidopsis thaliana. Plant Journal 45, 847-856, 2006. 

Ricinoleate (R) has many industrial uses. Its only commercial source is castor oil, in which ricinoleate constitutes 90% of the fatty acids (FA) (1). Castor beans contain toxic substances and are hazardous to grow, harvest, and process. Therefore, it is desirable to produce ricinoleate from a transgenic plant lacking these toxic substances. To develop a transgenic plant capable of producing a high level of ricinoleate in its seed oil, it is essential to understand the biosynthesis of castor oil. We previously established the biosynthetic pathway of castor oil and identified the key enzymatic steps of the pathway, which drive the ricinoleate into castor oil (2,3). We report here the identification and quantification of the molecular species of triacylglycerols (TAG, end products), phosphatidylcholines (PC, intermediate) and phosphatidylethanolamines (PE, intermediate) on the pathway incorporated from various [ C]-labeled FA and the comparison of the levels of their incorporation. 

We have elucidated the biochemistry of castor oil biosynthesis, an essential step in generating effective transgenic sources of a high ricinoleate oil. Because this aspect of our research has been described recently (6), and is discussed further in this volume (7), this paper will focus mainly on our other fatty acid of interest, cw-vaccenate. 

TABLE 1. Fatty acid composition of intact TAG and at sn-2 position of control and transgenic seed oil extracted from pooled seed samples. 

A. thaliana SLC1-1 Transformant Seed Lipid Analyses T2 seed from a large number of A. thaliana SLCl-1 transgenic lines (21 of 48) showed significantly increased oil contents (11- 49% increase in pg total fatty acids / 50 seeds) compared to non-transformed controls (n-WT), and pBI121 controls (without SLCl-1 insert, but with KAN selectable marker). Several lines exhibited dramatic increases in total VLCFA content, especially 20 1 and 22 1, and elevated proportions of VLCFAs. 

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