Plants unusual fatty acids production

Napier JA. The production of unusual fatty acids in transgenic plants. Annu. Rev. Plant Biol. 2007 58 295-319. 

The endoplasmic reticulum (ER) has traditionally been viewed as the primary source of phospholipids in plant cells. With the exception of cardiolipin, all of the common phospholipids can be produced by microsomal fractions. The ER also serves as the major site of fatty acid diversification. Although plastids do have the ability to synthesize polyunsaturated fatty acids, they are formed on acyl lipid substrates and are not typically exported. Thus, the ER desaturation pathways are of particular importance for developing seeds that store large quantities of 18 2 and 18 3. Pathways for the production of unusual fatty acids found primarily in seed oils have likewise been described in microsomes. Not surprisingly, the ER also appears to be instrumental in the formation of TGs and the lipid bodies in which they are stored (Section 7). 

Unusual Fatty Acids in Microorganisms and Their Production in Plants... 

Until recently the fatty acid composition of rapeseed oil was quite different from that of other edible vegetable oils from 40 to 60% of the fatty acid components of rapeseed oil consisted of the long chain fatty acids, erucic and eicosenoic. This unusual fatty acid composition has been the subject of numerous nutritional studies. Detrimental effects attributed to the long chain fatty acid components of rapeseed oil stimulated plant breeders to search for genetically controlled variation in these components. Rape plants which produce seed oil essentially without erucic acid were isolated (Ste-fansson et al., 1961) and this characteristic was incorporated into cultivars suitable for commercial production. The new "low erucic acid" rapeseed oils contain only the fatty acid components found in other edible vegetable oils traditionally used as food in the Western World. 

The fatty acid components constitute a unique and, from several aspects, very interesting characteristic of RJ. About 80-90% (on dry weight) of the fatty fraction of RJ is constituted by free fatty acids with exceptionally rare and unusual structures (Fig. 1). CrMitraiy to carboxylic acids with 14—20 carbon atoms that are usually found in animal or plant materials, RJ contains mainly small chain (8 up to 12 carbon atoms) hydroxy fatty acids (Table 1), dicarbox-ylic acids (Fig. 2), mmiohydroxyacids, and derivatives (Fig. 3) and dihydrox-yacids (Fig. 4). The main fatty acid of RJ is trans-lO-hydroxy-2-decenoic acid (1) and is followed by the saturated derivative 10-hydroxydecanoic acid (2) (Fig. 1). It is noteworthy that fatty acid 1 has never been detected in any other natural raw material or even in other bee products [9,10,16—24]. 

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