Seed oils of meadowfoam (Limnanthes douglasii,L. alba) contain very long-chain fatty acids of strategic importance for a number of industrial applications. These include the monoene 20 1?5 and the diene 22:2?5,?13. Engineering of meadowfoam-type oils in other oilseed crops is desirable for the production of these fatty acids as industrial feedstocks. Accordingly, we have targetedBrassica carinataand soybean (Glycine max) to trangenically engineer the biosynthesis of these unusual fatty acids. AnL. douglasiiseed-specific cDNA (designatedLim Des5) encoding a homolog of acyl-coenzyme A desaturases found in animals, fungi and cyanobacteria was expressed inB. carinata, which resulted in the accumulation of up to 10% 22:2?5,?13 in the seed oil. In soybean, co-expression ofLim Des5with a cDNA (Lim FAE1) encoding an FAEl (elongase complex condensing enzyme) homolog fromL. douglasiiresulted in the accumulation of 20:1?5 to approximately 10% of the total fatty acids of seeds. The content of C20 and C22 fatty acids was also increased from<0.5% in non-transformed soybean seeds to>25% in seeds co-expressing theLim. douglasii Des5andFAE1cDNAs. In contrast, expression of theLim Des5inArabidopsisdid not produce the expected 20:2?5,?11 in the seed oil. Cumulatively, these results demonstrate the utility of soybean andB. carinatafor the production of vegetable oils containing novel C20 and C22 fatty acids, and confirm that the preferred substrates of theLim Des5are 20:0 and 22:1?3, respectively. [ABSTRACT FROM AUTHOR]