Lipid characterization in vegetative tissues of high saturated fatty acid sunflower mutants.

Modifications of the fatty acid composition of plant vegetative tissues produce deficient plant growth. To determine the expression of the seed high-saturated sunflower (Helianthus annuus L.) mutant character during the vegetative cycle, five sunflower mutant lines (three high-stearic and two high-palmitic) have been studied during their germination and vegetative cycle. No significant variations with regard to the control lines were observed in the mutant vegetative tissue lipids; however, during seed germination important differences between lines were found. Although in the early steps of germination the palmitic and stearic acid levels in the respective mutants seedling cotyledons continued being higher than those of the control lines, they decreased and reached values similar to the controls, except in CAS-3. Variations in the cotyledon palmitic acid content with regard to the control line were also observed in high-stearic mutants, suggesting the expression of a modified acyl-ACP thioesterase or recycling of seed fatty acids during seedling development.

Characterization of polar and nonpolar seed lipid classes from highly saturated fatty acid sunflower mutants.

The seed lipids from five sunflower mutants, two with high palmitic acid contents, one of them in high oleic background, and three with high stearic acid contents, have been characterized. All lipid classes of these mutant seeds have increased saturated fatty acid content although triacylglycerols had the highest levels. The increase in saturated fatty acids was mainly at the expense of oleic acid while linoleic acid levels remained unchanged. No difference between mutants and standard sunflower lines used as controls was found in minor fatty acids: linolenic, arachidic, and behenic. In the high-palmitic mutants palmitoleic acid (16:1n-7) and some palmitolinoleic acid (16:2n-7, 16:2n-4) also appeared. Phosphatidylinositol, the lipid with the highest palmitic acid content in controls, also had the highest content of palmitic or stearic acids, depending on the mutant type, suggesting that saturated fatty acids are needed for its physiological function. Positional analysis showed that mutant oils have very low content of saturated fatty acids in the sn-2 position of triacylglycerols, between the content of olive oil and cocoa butter.