ACYLTRANSFERASES FROM BASIC SCIENCE TO MODIFIED SEED OILS

Different discrete acyltransferases are involved in glycerolipid biosy nthesis, which occurs in plastids, mitochondria and endomembranes, mai nly in the endoplasmic reticulum of plant cells. In each compartment a glycerol-3-phosphate and 1-acylglycerol-3-phosphate acyltransferase c atalyze the stepwise acylation of glycerol-3-phosphate to 1,2-diacylgl ycerol-3-phosphate, the key intermediate in the biosynthesis of the va rious glycerolipids. These acyltansferases play an important role in e stablishing the typical fatty acid patterns of the major polar membran e lipids. This also holds true for the microsomal acyltransferases inv olved in triacylglycerol synthesis where a 1,2-diacylglycerol acyl tra nsferase catalyzes the third acylation reaction. Consequently, the act ivities of plant acyltransferases are indispensable for the formation of both membrane and storage lipids, and their properties can be decis ive determinants of certain plant traits. Recently, the importance of acyltransferases, especially of 1-acylglycerol-3-phosphate acyltransfe rases, in determining oil quality and usability for specific markets h as been confirmed by genetic engineering. Chimeric 1-acylglycerol-3-ph osphate acyltransferase genes have been successfully utilized to achie ve the synthesis of rapeseed oil with homogeneous fatty acid distribut ions, such as trierucin and trilaurin, desired for industrial applicat ions. Moreover, evidence has been provided that expression of acyltran sferase genes in transgenic rapeseed plants can improve not only oil q uality but also oil yield.