Transgenic seed

Fig. 16.1 The terminator technology which can be used to prevent the growth of volunteer plants from dispersed transgenic seed.

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.

A cDNA encoding such a thioesterase was isolated from seeds of the California Bay tree and transformed into rapeseed. As shown in Fig. 11, the introduction of this specialized thioesterase resulted in transgenic seeds that produced up to 60 mol% lauric acid. The plants grow normally and oil yields are very similar to those of the untransformed cultivars. Commercial production of high lauric rapeseed oil began in 1995. Although this crop has the potential to provide a new, non-tropical source of lauric oils for... 

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.

In 2005, 80 million pounds, about one pound per acre, of pesticides were applied to soybean crops in the United States. The most common pesticide (79%) was glypho-sate isopropylamine salt (Fig. 5.14). The popularity of glyphosate is due to the fact that 91% of the U.S. soybean crop utilizes transgenic seed specifically resistant to the herbicide. This allows farmers the ability to spray their fields once for weeds without killing the soybeans. It is estimated that 77 million pounds of herbicide were ap-... 

Ricinoleic acid is only one of four HFAs produced in transgenic seeds, which also accumulate densipolic, lesquerolic and a small amount of auricolic acid. This suggests that Arabidopsis and related Lesquerella species metabolize ricinoleic acid in a similar way. 

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

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