A Comparison of Sterol and Long Chain Fatty Alcohol Biosynthesis in Sorghum Bicolor

There are two major lipid pathways which operate in crop plants viz., the isopentenoid and fatty acid pathways. To our knowledge, no previous investigation has attempted a comparative study of the composition, biosynthesis and function of the major end products of these pathways. However, in order to assess the physiological importance of having a select lipid profile to, for instance, proceed from one developmental stage into another, the lipid composition in toto-subcellular and surface wax, must be defined. As discussed in what follows, we have observed in this and our other work on sorghum1–5 that the lipid profile changes dramatically during its development (Table 1). Thus, lipids essentially absent, i.e., pentacyclic triterpenoids, in the seedlings become quantitatively important bulk constituents of the blade’s membrane and wax architectures as the plant enters into the flowering stage. Other membrane components have been identified by GLC-MS and ‘HNMR eg., fatty acids (myristate, palmitate, oleate, linoleate and linolinate), long chain fatty alcohols (C22-C32-Table 2) and alkanes in the blades.