Manipulation of lipid metabolism in transgenic plants: biotechnological goals and biochemical realities.

Introduction One of the major objectives of modern plant biotechnology is to manipulate the amount and quality of seed storage lipids, particularly for medium to high-value industrial applications. In biochemical terms, this involves the manipulation of the biosynthetic pathways involved in storage triacylglycerol formation. The conventional approach to doing this has been to clone genes that are believed to be involved in the biosynthesis of novel seed oils from donor plant species and to transfer these genes into existing successful oilseed crop species that are readily transformable, such as rapeseed or soybean. 1 lowever, it is becoming increasingly evident that our expertise in molecular genetic manipulation sometimes considerably outstrips our knowledge of lipid biosynthetic pathways in plants. Although some modest successes have been achieved in altering seed oil content, particularly in rapeseed and soybean, it is now apparent that some aspects of the metabolic pathways of storage triacylglycerol formation and their reglation are much more complex than was suspected hitherto. This has stimulated an increased emphasis on the use of transgenic plants for the study of lipid biochemistry, a process which has been facilitated by the recent isolation of numerous genes involved in plant fatty acid biosynthesis and modification 111. In this article, recent progress in the use of transgenic plants in the study of plant lipid metabolism and its manipulation will be briefly surveyed.