TRIACYLGLYCEROL BIOSYNTHESIS AND GENE-EXPRESSION IN MICROSPORE-DERIVED CELL-SUSPENSION CULTURES OF OILSEED RAPE

The effect of sucrose concentration on triacylglycerol biosynthesis an d associated gene expression was examined in a microspore-derived cell suspension culture of oilseed rape (Brassica napus L. cv. Jet Neuf), The triacylglycerol content of the cells increased about 5-fold on a f resh weight basis when the sucrose concentration in the growth medium was raised from 2% to 22% (w/v), The specific activity of microsomal d iacylglycerol acyltransferase (EC 2.3.1.20) and its activity per unit fresh weight increased about 2.5-fold and 6-fold, respectively, when s ucrose concentration was increased from 2% to 14%, mRNA encoding the m ajor oleosin also appeared to increase in abundance over the 2-14% suc rose concentration range when RNA fractions were analysed by the rever se transcription-polymerase chain reaction, The sucrose-mediated incre ases in diacylglycerol acyltransferase activity and oleosin mRNA indic ated that the cell suspension could be a useful research tool for the identification of cDNAs encoding triacylglycerol biosynthetic enzymes and associated proteins.