Knockout of KASIII regulation changes fatty acid composition in canola (Brassica napus)

In contrast to the dominating unsaturated C-18 fatty acid, medium-chain fatty acids (MCFA) are nearly absent in the oil of common canola. Modification of canola oil towards higher contents of C-8 to C-14 fatty acids would create new possibilities for oleochemical usages, in both the nutritional and the non-food sectors. For this purpose, spring oilseed rape (cv. 'Drakkar') was genetically modified by introduction of MCFA-encoding genes from Cuphea species containing approximately 90% MCFA in their Two different single constructs involving the 3-ketoacyl-acyl carrier protein seed oil. synthase (KAS)III from C. lanceolata were used, one harbouring the wild-type gene, C/KASIIIbwt, and the other containing the point-mutated gene, C/KASIIIbmut, along with two double constructs containing C/KASIIIbmut in combination with a medium-chain thioesterase gene from C. lanceolata (C/FatB3) or C. hookeriana (ChFatB2). For both single-gene constructs, a phenotype with an increased content of MCFA was not detected; however, the C/KASIIIbwt transformants produced up to 6.7% palmitic acid (C-16). In T2 seeds bearing the C/KASIIIbmut/C/FatB3 double-gene construct, contents of up to 2.9% capric (C-10) and 11.4% palmitic acid were achieved. The best transformant with the gene construct C1KASIIIbmut/ChFatB2 contained 1.4% caprylic acid (C-8) and 7.9% C-10, and these results were confirmed in T3 seeds.