Changes in the acyl lipid composition of maturing embryos of oilseed r
ape (Brassica napus cv Shiralee) were quantified in plants cultivated
in growth rooms. Rapid deposition of storage triacylglycerols began ar
ound 16 days after pollination (DAP) and continued till about 40 DAP a
fter which seed desiccation proceeded. Diacylglycerols were present in
significant amounts during the rapid phase of oil accumulation, which
may suggest a rate limitation in carbon flux at the level of diacylgl
ycerol acyltransferase. Analysis of the fatty acid moieties of differe
nt lipid classes revealed that the pattern for triacylglycerols rapidl
y assumed that of the mature seed oil. The polar lipid fraction, in co
ntrast to storage triacylglycerols, contained much less oleate (especi
ally in immature seeds) reflecting the role of such lipids in membrane
function. The acyl composition of the diacylglycerol fraction was int
ermediate between those of the triacylglycerol and the polar lipids ex
cept for mature seeds. Overall, for seeds raised in growth rooms, the
final lipid composition and its detailed acyl quality agreed excellent
ly with field-grown material.