Lipidomic analysis reveals differential defense responses of Taxus cuspidata cells to two elicitors, methyl jasmonate and cerium (Ce 4+)

Abstract

Methyl jasmonate (MeJA) and cerium (Ce 4+) elicitation share common features of increasing taxol accumulation of Taxus cuspidata cells. Interestingly, Ce 4+ induces programmed cell death (PCD), but this phenomenon is not observed with MeJA elicitation. Here, using a lipidomic approach to measure more than 100 membrane glycerophospholipids of T. cuspidata cells quantitatively, we discovered that lysophosphatidylcholine (LysoPC), phosphatidic acid (PA) and phosphatidylcholine were three potential lipid markers that were responsible for the differences between Ce 4+-induced cells and MeJA-induced cells. Compared with MeJA elicitation, marked increase of phospholipase D (PLD) activity was observed following Ce 4+ elicitation, suggesting that the PLD activation and high concentrations of PA production might mediate the PCD. Rapid increase of phospholipase A 2 (PLA 2) activity caused the release of fatty acids and LysoPC following Ce 4+ elicitation, which enhanced endogenous jasmonic acid (JA) accumulation. In contrast, PLA 2 activity was poorly induced following MeJA elicitation. PLA 2 inhibitor suppressed not only JA accumulation but also taxol production, suggesting that the PLA 2 activation mediated Ce 4+-induced taxol production partially through a JA-dependent signaling pathway. These results demonstrate that differential alternation of glycerolphospholipids caused by phospholipases constitutes an important step in cell death response to Ce 4+ and increasing taxol production.