Plant seed oils, fatty acid composition

Medium chain fatty acids (C,-Ci4) are unusual fetty adds found in the seed oils of several plant species such as Cuphea and California bay [1]. Medium chain fetty acids are produced by premature chain termination of fetty acid synthesis, mediated by a medium chain acyl-ACP thioesterase (MCTE) [2,3]. Since medium chain fetty acids are a valuable renewable resource, one goal of researchers has been to develop a medium chain-producing annual crop plant using genetic transformation [4]. Workers at Calgene transformed Brassica napus with California bay medium chain acyl-ACP thioesterase cDNA, testing the ability of a seed specific napin promote or the constitutive CaMV 35S promoter to alter seed oil fatty acid composition. We have used these transformants to evaluate possible roles for acyl-ACP chain length termination in the control of fatty acid synthesis. 

Engelter, C. and Wehmeyer, A. S. (1970). Fatty acid composition of oils of some edible seeds of wild plants. /. Agric. Food Chem. 18, 25-26. 

Robertson, J. A., Morrison, W. H., Ill, and Wilson R. L., Effects of Planting Location and Temperature on the Oil Content and Fatty Acid Composition of Sunflower Seeds, USDA Agric. Results ARR-S-3, U.S. Dept. Agriculture, Washington, DC, 1979. 

Seedfats are characterized by low contents of saturated fatty acids. They contain palmitic, oleic, linoleic, and linolenic acids. Sometimes unusual fatty acids may be present, such as erucic acid in rapeseed oil. Recent developments in plant breeding have made it possible to change the fatty acid composition of seed oils dramatically. Rapeseed oil in which the erucic acid has been replaced by oleic acid is known as canola oil. Low linolenic acid soybean oil can be obtained, as... 

Buffalo gourd (Cucurbita foetidissima). The buffalo gourd is a vine-Uke plant that grows in semiarid regions of the United States, Mexico, Lebanon, and India. The seed contains good quality oil (32-39%) and protein. The oil is very variable in fatty acid composition, thus lending itself to seed breeding. A typical sample contains 16 0 (9%), 18 0 (2%), 18 1 (25%), and 18 2 (62%) (88). 

Lipids with high levels of polyunsaturated fatty acids are considered desirable by many nutritionists because these lipids help to maintain low levels of blood cholesterol and favorable levels of serum high density lipoproteins. Many efforts are now directed at modification of the fatty acid composition in plants, especially the composition of seed oils (5). Genetic improvement of soybean oil is an especially desirable goal since the small amount of a-linolenic acid present in the oil causes flavor instability. 

Safflower oil is the seed oil of the thistle-like safflower plant, thriving in the west of the USA, Mexico, North Africa and India. The plant can be grown under fairly arid conditions. The seeds resemble small sunflower seed kernels and can be harvested mechanically. Like corn oil the fatty acid composition is similar to that of sunflower oil. Safflower oil has a high oxidative stability and is being used increasingly in salad oils and dietetic margarines because of its high content of linoleic acid. 

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. 

Vereshchagin, AG. Biochemistry of triglycerides. M Nauka, 1972, 1-308. (In Russian) Graham, I. Seed storage oil mobilization. Annu. Rev. Plant Biol, 2008, 59,115-142. Berezhnaya, GA Ozerinina, OV Yeliseev, IP Tsydendambaev, VD Vereshchagin, AG. Developmental changes in the absolute content and fatty acid composition of acyl lipids of sea buckthorn fruits. Plant Physiol, Biochem., 1993, 31, 323-332. 

Seed oils vary widely in fatty acid composition (Section 3.3). One fatty acid often predominates, is sometimes of unusual structure and is characteristic of a particular plant family (Gurr, 1980). The... 

To detennine whedier die same genes control fatty acid composition in die seed oil and in polar lipids of different tissues, we compared die overall fatty acid composition of seeds, roots and leaves (Table 1, Table 2). Deficiencies in C18 2 and C18 3 desaturation were not restricted to (he seeds. The mutations were also expressed in roots and leaves. Modifications of leave lipids were low in comparison to roots indicating changes in extrachlorplast lipids. A substantial reduction of C18 3 and concomitant increase of C18 2 was observed in die roots of all low C18 3 mutants. For membrane function diis substitution of C18 3 by C18 2 seems to be tolerated Goe 9 and cv. Apollo have no deficiencies in plant development and they are high yielding. 

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