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An assessment of the transcript abundance of several fatty acid and lipid biosynthetic genes has been made. Total RNA was extracted from embryos at different stages of development and mRNA was analysed by quantitative Northern blots and used to probe cDNA arrays. Central fatty acid synthase components were present at different steady-state levels, but at constant ratios throughout development; ancillary components were generally expressed at higher levels, but at constant ratios over the period of maximum fatty acid biosynthesis.

Plants with an antisense construct to β-ketoacyl-acyl carrier protein reductase have reduced seed and leaf fatty acid contents and show distinct phenotypes, including leaf curl, stunted growth and wrinkled seeds. The carbon resource allocation is altered in both of these tissues. In leaves there is an inability to synthesize transient starch and in seeds embryogenesis is foreshortened and storage proteins accumulate prematurely.

We have generated antisense plants of Brassica napus, targeting either the cytoplasmic Type I acetyl-CoA carboxylase or the β-ketoacyl-acyl carrier protein reductase of the Type II dissociable fatty acid synthase, in order to investigate the importance of these components in regulating lipid metabolism in plants. Using a range of down-regulated plants, it has become clear that down-regulation of these genes also causes down-regulation of other components of lipid metabolism, at the activity, translational and transcriptional levels. These plants exhibit effects, not immediately predicted, on oil yield and carbon resource allocation in seeds.