Correlation of ATP/citrate lyase activity with lipid accumulation in developing seeds of Brassica napus L.

The temporal distribution of ATP/citrate lyase (ACL) activity in developing seeds of Brassica napus L. closely paralleled both that of acetyl-CoA carboxylase and the overall rate of lipid biosynthesis. Maximum ACL activities (250 nmol acetyl-CoA formed min-1.g fresh seed) were recorded between 35 to 42 d after pollination and, if the in vitro data could be extrapolated to the situation in vivo, could account for half of the acetyl-CoA required for the measured rate of fatty acid biosynthesis during seed development. The enzyme appeared to be localized in a subcellular compartment, which was clearly separated from mitochondria on a sucrose gradient and by differential centrifugation, and which corresponded to the chloroplast organelle.