Characterization of the glycerolipid composition of a high‐palmitoleic acid sunflower mutant

Abstract

The glycerolipid composition of a high-palmitoleic acid sunflower (Helianthus annuus L.) mutant accumulating up to 20% of n-7 fatty acids was studied. This line produces oil with a complex triacylglycerol (TAG) composition, containing species that have not been previously identified in sunflower. In this regard, palmitoleic acid was esterified in an unexpected way in the three positions of the TAG molecules. The polar glycerolipid composition of the mutant was also studied, in order to identify and quantify the changes in membrane lipids imposed by the sunflower enzymatic machinery during the accumulation of the unusual n-7 fatty acids. The high-palmitoleic mutant accumulated important quantities of n-7 fatty acids in the polar lipid fraction, especially in the phosphatidylcholine lipid class. However, the total polar lipid content of these lines was not affected. On the other hand, the mutations responsible for the n-7 lipid accumulation induced an important decrease in the oil yield of the new mutant.

Effect of different environmental stresses on the expression of oleate desaturase genes and fatty acid composition in olive fruit

“…In agreement with this idea, palmitolinoleic acid is not detected in olive fruit mesocarp during the ripening process, where olive FAD2-2 but not FAD2-1 gene is highly expressed especially in the Arbequina variety (Hernández et al, 2009). Regarding the metabolic origin of the palmitoleic acid in the ER, palmitic acid could be desaturated in the plastid by the action of the D9 stearoyl-ACP desaturase to palmitoleic acid, which could be exported to the cytosol and incorporated into phospholipids for further desaturation by the FAD2, as it has been described in a high-palmitoleic acid sunflower mutant (Salas et al, 2007). Supporting this hypothesis, the induction of the D9 stearoyl-ACP desaturase gene in wounded olive leaves has been reported (Benítez et al, 2005), which is in agreement with the increase of palmitoleic and oleic acid detected in olive fruit mesocarp after wounding ( Fig.…”

Vegetable oil basestocks for lubricants

“…In the past years genes coding for desaturases responsible for the synthesis of this fatty acid have been isolated and are ready to use for the production of oil crops enriched in palmitoleic acid (Cahoon et al, 2004). In this regard, a sunflower line producing up to 15% palmitoleic acid has been reported (Salas et al 2007) to be produced by techniques of breeding and mutagenesis. However, the use of these mutants for lubricant production is hampered by their still high levels of linoleic and palmitic acids.…”

Acyl-ACP thioesterases from macadamia (Macadamia tetraphylla) nuts: Cloning, characterization and their impact on oil composition

“…Thus, the desaturase cloned from that species did not show unusual substrate specificity. In addition, the CAS-37 sunflower (Helianthus annuus) mutant is reported to accumulate n-7 fatty acids in seeds at similar levels to those found in macadamia nuts [12,15]. As stated above, the biochemical characterization of this mutant did not show altered substrate specificity from the endogenous acyl-ACP desaturase activity but rather, the high n-7 phenotype was due to a reduction in the activity of the FAS II complex, which is the responsible for most palmitoyl-ACP elongation [16].…”