FATTY-ACID COMPOSITION IN MICROSPORE-DERIVED SECONDARY EMBRYOS OF BRASSICA-NAPUS L

Fatty acid (FA) composition was determined in secondary embryos (SeEs) of Brassica napus L. of the cv. 'Topas' and 'Janetzki', and compared with the FA composition in microspore-derived embryos (MDEs) and seeds . SeEs of 'Topas', a rapeseed cultivar with low erucic acid, revealed the same FA composition as observed in the MDEs. The FA pattern was, i n most of the cases, independent of the procedures used for induction of SeEs e.g. low density cultures, transversal wounding, auxin treatme nt, and light conditions. However, non-embryogenic calli, as well as l eaves from greenhouse- and in vitro-grown material had a FA compositio n distinctly different from the MDEs or SeEs. SeEs with an abnormal ph enotype revealed differences in FA composition compared to MDEs or SeE s, but was distinct from the composition of non-embryogenic tissues. V irtually no erucic acid (22:1) or eicosaenoic acid (20:1) could be det ected in SeEs of 'Topas'. However, its presence in SeEs of 'Janetzki', a high erucic acid rapeseed cultivar, demonstrates that SeEs contain embryo-specific FAs. Under standard culture conditions, the levels of 22:1 and 20:1 were the same as observed in MDEs, which was approximate ly half the content observed in the seeds. The similarity in FA compos ition between SeEs and MDEs, of both low and high erucic acid rapeseed cultivars, is a unique characteristic which differs from most other s omatic embryogenic systems.