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

Abstract

AbstractIn contrast to the dominating unsaturated C18 fatty acid, medium‐chain fatty acids (MCFA) are nearly absent in the oil of common canola. Modification of canola oil towards higher contents of C8 to C14 fatty acids would create new possibilities for oleo‐chemical 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 seed oil. Two different single constructs involving the 3‐ketoacyl‐acyl carrier protein synthase (KAS)III from C. lanceolata were used, one harbouring the wild‐type gene, ClKASIIIbwt, and the other containing the point‐mutated gene, ClKASIIIbmut, along with two double constructs containing ClKASIIIbmut in combination with a medium‐chain thioesterase gene from C. lanceolata (ClFatB3) or C. hookeriana (ChFatB2). For both single‐gene constructs, a phenotype with an increased content of MCFA was not detected; however, the ClKASIIIbwt transformants produced up to 6.7% palmitic acid (C16). In T2 seeds bearing the ClKASIIIbmut/ClFatB3 double‐gene construct, contents of up to 2.9% capric (C10) and 11.4% palmitic acid were achieved. The best transformant with the gene construct ClKASIIIbmut/ChFatB2 contained 1.4% caprylic acid (C8) and 7.9% C10, and these results were confirmed in T3 seeds.