Formation of trierucoylglycerol (trierucin) from 1,2‐Dierucoylglycerol by a homogenate of microspore‐derived embryos ofBrassica napus L

Homogenates of microspore‐derived embryos of rape (Brassica napus L.) incubated with [1‐14C]erucoyl‐CoA and 1,2‐dierucoylglycerol are able to assemble trierucoyl‐glycerol (trierucin). In addition, radioactive triacylglycerols are formed by transferring [1‐14C]‐erucoyl moieties to endogenous lipid precursors. Stereospecific analysis of radioactive triacylglycerols revealed that labeled erucoyl moieties had been incorporated exclusively into thesn‐1,3 positions with more than 95% of radioactivity in thesn‐3 position. No incorporation of labeled erucic acid into thesn‐2 position has been observed. All data agree with the involvement of 1,2‐diacylglycerol acyltransferase (E.C. 2.3.1.20), which utilized 1,2‐dierucoylglycerol as well as endogenous 1,2‐diacylglycerols as acceptors of erucoyl moieties. This result is of particular interest for the genetic modification of rape and other Cruciferae for producing trierucin in their seed oils.