Microspore embryogenesis of high sn-2 erucic acid Brassica oleracea germplasm

Brassica oleracea accessions possess traits that would be useful in commerc ial Brassica crops. These traits can be studied more effectively through th e production of doubled haploid plants. Nineteen B. oleracea accessions fro m several subspecies possessing significant sn-2 erucic acid were screened for suitability for microspore culture using techniques well established fo r Brassica. Fifteen of the 19 accessions produced embryos. Genotypic differ ences were observed with embryogenesis ranging from 0 to 3000 embryos/100 b uds. Embryogenesis was improved for two of four accessions by initiating cu ltures in NLN medium with 17% sucrose, then reducing sucrose to 10% after 4 8 h. An increase in embryogenesis for the same two accessions was observed when microspores were cultured at a density of 100 000/ml rather than 50 00 0 microspores/ml. A culture temperature of 32 degrees C for 48 h was benefi cial for three of the four accessions when compared to a longer incubation period (72 h) or a higher temperature (35 degrees C). One accession line, B o-1, was found to produce microspore-derived embryos which contained triacy lglycerols with significant proportions of erucic acid at the sn-2 position .