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possible pathways-a) membrane biosynthesis, b) pathway for cell growth and c) key pathway

for yielding biofuel precursors.TAG is also one of the biofuel precursors. The conversion of
acyl- CoA to TAG requires the provision of 1, 2 diacylglycerol and a DGAT to catalyze

transfer the acyl chain shown in the figure. 4 (Ruffing, 2013).
DGAT enzymes play a chief role in triacylglycerol biosynthesis. Diacylglycerol

acyltransferases (DGATs) catalyse the final step of triacylglycerol (TAG) biosynthesis in the
Kennedy pathway, and play a critical role during TAG accumulation in developing

oleaginous seeds (Hobbs et al., 1999). Kennedy pathway involves esterification of two acyl

chains from acyl CoA to glycerol 3- phosphate to form phosphatidic acid and subsequent
removal of phosphate to form Diacylglycerol (DAG). Further, diacyylglycerol acyltransferase

(DGAT) converts DAG to TAG. This enzyme is synthesized within the membranes of the

endoplasmic reticulum and then released into the cytoplasm in the form of oil bodies. The
surfaces of oil bodies are coated with a monolayer of phospholipid associated with oleosin,

the major protein of oil bodies. There are two different classes of DGAT identified in various
plant species which might be involved in the overall variation in triacylglycerols in the oil

among the plant species as it is a key enzyme in determining the levels of triacylglycerols in
seed. A detailed study of these genes is expected to resolve the much needed metabolic

engineering needs of biofuel crops.

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