32 Glycerolipids

Abstract

The membranes of a typical plant cell collectively contain several hundred chemically distinct lipids. The functional significance of this chemical complexity and the mechanisms that regulate the amount of each constituent are not known. These problems may be subdivided into a wide range of more specific questions that direct much of the current research on plant and animal lipids. Most research on lipids in Arabidopsis has been focused on problems in three major areas: the biosynthesis of membrane glycerolipids, the roles of these lipids in the structure and function of membranes, and the synthesis of storage lipids (triacylglycerols) in seeds. Relatively little work has been published concerning the role of lipid derivatives, such as jasmonate (Farmer and Ryan 1990) and phosphoinositides (Blatt et al. 1990; Cote and Crain 1993), as components of signal transduction pathways. Similarly, in Arabidopsis, there appears to have been very little work on sterols (Patterson et al. 1993), sphingolipids, or chlorophylls, which are all important membrane components (Somerville 1986). The various functions of acyl lipids — involving fatty acids, which are produced from the 2-carbon precursor acetate — and the roles of isoprene lipids, produced from a 5-carbon precursor which itself is derived from acetate, are listed in Table 1 along with references to appropriate reviews. The role of fatty acid derivatives in the formation of cutin and wax are described elsewhere in this volume.

Although Arabidopsis contains only a small subset of the fatty acids found in various plant species (Hilditch and Williams 1964; Harwood 1980), the...