The role of Delta6-desaturase acyl-carrier specificity in the efficient synthesis of long-chain polyunsaturated fatty acids in transgenic plants.

摘要

The role of acyl-CoA-dependent Delta6-desaturation in the heterologous synthesis of omega-3 long-chain polyunsaturated fatty acids was systematically evaluated in transgenic yeast and Arabidopsis thaliana. The acyl-CoA Delta6-desaturase from the picoalga Ostreococcus tauri and orthologous activities from mouse (Mus musculus) and salmon (Salmo salar) were shown to generate substantial levels of Delta6-desaturated acyl-CoAs, in contrast to the phospholipid-dependent Delta6-desaturases from higher plants that failed to modify this metabolic pool. Transgenic plants expressing the acyl-CoA Delta6-desaturases from either O. tauri or salmon, in conjunction with the two additional activities required for the synthesis of C20 polyunsaturated fatty acids, contained higher levels of eicosapentaenoic acid compared with plants expressing the borage phospholipid-dependent Delta6-desaturase. The use of acyl-CoA-dependent Delta6-desaturases almost completely abolished the accumulation of unwanted biosynthetic intermediates such as gamma-linolenic acid in total seed lipids. Expression of acyl-CoA Delta6-desaturases resulted in increased distribution of long-chain polyunsaturated fatty acids in the polar lipids of transgenic plants, reflecting the larger substrate pool available for acylation by enzymes of the Kennedy pathway. Expression of the O. tauri Delta6-desaturase in transgenic Camelina sativa plants also resulted in the accumulation of high levels of Delta6-desaturated fatty acids. This study provides evidence for the efficacy of using acyl-CoA-dependent Delta6-desaturases in the efficient metabolic engineering of transgenic plants with high value traits such as the synthesis of omega-3 LC-PUFAs. copyright 2011 The Authors. Plant Biotechnology Journal copyright 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.