SELECTION FOR FATTY-ACID COMPOSITION IN MICROSPORE-DERIVED EMBRYOIDS (MDE) OF RAPESEED, BRASSICA-NAPUS (L.)

Embryoids derived from microspores of oilseed rape are used today to attain rapid production of homozygous lines as well as to study the accumulation of storage products (proteins, lipids). Microspore-derived embryoids (MDE) from cultivars both low and high in erucic acid, respectively, can be induced to accumulate triacylglycerols with a fatty acid composition similar to that in seed of the same genotype. By means of this method the influence on fatty acid composition (FAC) of culture condition and ploidy level of MDEs were analysed in the Brassica napus cvs. <Duplo> (low erucic acid) and <Janetzki> (high erucic acid). Single cotyledons with a dry weight of 2-15 mg were reliably analysed for their FAC and the remaining embryoids were regenerated to plants. Single embryoids of the cv. <Duplo> showed a FAC identical to that of the seeds, e.g. C18:167%, C18:213%, C18:37%. For the cv. <Janetzki>, an addition of 15 mu M ABA to the incubation medium and cultivation at a temperature of 15 degrees C on a shaker did raise the content of erucic acid from 25% to 38.6% (cf. 45% in the seed oil). Culture of the MDEs in continuous darkness (at 15 degrees C + 15 mu M ABA) further improved the erucic acid content to 40.3%. On the other hand, ploidy level of the embryoids did not influence fatty acid composition.