Lipid Characterization of a High-Stearic Sunflower Mutant Displaying a Seed Stearic Acid Gradient

摘要

In the seeds of the high-stearic sunflower mutant CAS-14 a gradient of increasing stearic acid exists from the embryo to the terminal extreme of the cotyledon.This gradient modifies the fatty acid composition of the total lipids,triglycerides,and phospholipids,which can best be appreciated in the triglycerides that pass from 16% stearic acid content in the embryo to 37.1% in the other extreme.This increase in the triglycerides occurs principally at the cost of the oleic acid content.The stearic content at position sn-2 of triglycerides is low,rising from 1.3% in the embryo to 3.4%,whereas at positions sn-1 +3 the stearic content is high and augments from 25.2% in the embryo to 41.0% at the other extreme.The molecular species of triglycerides are also modified;the disaturated triglycerides increase from 15.5 to 51.7%.Furthermore,for the first time in sunflower seeds,it is demonstrated that trisaturated triglycerides are present,arising probably due to a modification in the acyltransferase system that synthesizes the triglycerides.