Use of transgenic plants and mutants to study the regulation and function of lipid composition

Mutants and transgenic plants with altered expression of genes implicated in lipid metabolism are providing fresh insights into the regulation and function of lipid composition. To date, several genes encoding fatty acid desaturases, acyltransferases, a thioesterase, a lipid transfer protein and an isoform of acyl-carrier protein have been introduced into transgenic plants. Despite the fact that some of these transgenic plants had large alterations in lipid composition, they showed surprisingly little phenotypic variation from wild-type plants. Although detailed analyses of these plants are just beginning, several theories regarding the roles of particular genes in various plant processes, such as cold tolerance and transfer of lipids between membranes, have been either substantiated or discarded on the basis of the data already obtained. In addition, constructs that contain the promoter regions of genes implicated in lipid metabolism fused to reporter genes have been introduced into transgenic plants and are providing some clues as to how lipid composition is regulated.