Manipulating desaturase activities in transgenic crop plants.

The properties of edible vegetable oils are determined to a large extent by the relative content of the triacylglycerol fatty acids. The degree of saturation of these fatty acids can determine the functional, sensory and nutritional value of the oil. One method of altering the unsaturated fatty acid content of oilseeds is by manipulating the expression of desaturase genes of these plants. Manipulating the expression of desaturase genes in transgenic crops such as soybean, maize and canola (oilseed rape) has led to oils with improved functionality and nutrition. We have also been successful in manipulating the fatty acid content of domesticated oilseed plants by expressing heterologous desaturase and desaturase-related genes from exotic plants that produce unusual fatty acids. We have discovered that metabolic regulation, the number of genetic alleles that encode fatty acid biosynthetic enzymes, and the movement of fatty acids between complex lipids in the cell, all have a role in determining the effect of a transgene on the phenotype of the crop plant and the fatty acid composition of its seed oil.