Function of ceramide synthases on growth, ganoderic acid biosynthesis and sphingolipid homeostasis in Ganoderma lucidum

Ceramide synthases (CERSs) catalyse an N-acyltransferase reaction using long-chain base (LCB) and fatty acyl-coenzyme A (CoA) as substrates to synthesize ceramide (Cer), which is the backbone of all complex sphingolipids. In the present study, three CERSs (LAG1, LAG2 and LAG3) form Ganoderma lucidum were analysed. The silencing of lag1 by RNA interference reduced ganoderic acid biosynthesis and Cer and complex sphingolipids contents, which contain long-chain-fatty-acids (LCFAs, including C16 and C18). In contrast, the silencing of lag2 or lag3 did not result in obvious phenotypic and sphingolipid homeostasis changes, although the lag2/lag3 double-silenced mutants exhibited increased ganoderic acid biosynthesis as well as reduced growth, reduced Cer and complex sphingolipids contents, which contain very-long-chain fatty acids (VLCFAs, including C22, C24 and C26). The results of the present study indicate that the three assayed CERSs have distinct physiological functions and substrate specificities in G. lucidum.