ABSTRACT
Sunfl ower is one of the four most important oilseed crops in the world, and the nutritional quality of its edible oil ranks among the best vegetable oils in cultivation. Typically up to 90% of the fatty acids in conventional sunfl ower oil are unsaturated. Information obtained in recent years regarding the enzymes involved in fatty acid synthesis can now be applied to develop novel sunfl ower lines by incorporating enzymes with specifi c characteristics into lines with a defi ned background. Serrano-Vega et al. (2005) generated three highly saturated mutant lines in this way and characterized their fatty acids content. The new high-palmitic, low-palmitoleic lines CAS-18 and CAS-25; the latter on a high-oleic background, were selected from the high-stearic mutant CAS-3 by introducing a defi cient stearic acid desaturase in a high-palmitic background from the previously developed mutant lines CAS-5 and CAS-12, respectively. As such, desaturation of palmitic acid and synthesis of palmitolic acid and its derivatives (asclepic and palmitolinoleic acids) were reduced in these high-palmitic lines, increasing the stearic acid content. Likewise, introducing a fatty acid thioesterase from a highpalmitic line (CAS-5) into the high-stearic CAS-3 increased stearic acid content from 27 to 31% in the new high-stearic line CAS-31. As previously described in high-palmitic lines, high growth temperatures did not reduce the linoleic acid content of the oil. Further, the fatty acid composition of triacylglycerol, diacylglycerol, and phospholipids was modifi ed in these lines. Besides a high degree of saturation, the triacylglycerol from these new
oils have a low content of saturated fatty acid in the sn-2 position. The alpha asymmetric coeffi cient obtained also indicates that the saturated fatty acids are asymmertrically distributed within the triacylglycerol molecules. The disaturated triacylglycerol content rose from 31.8 to 48.2%. These values of disaturated triacylglycerol are the highest in a temperate oilseed.
