Low-molecular-weight precursors for defense-related cell wall hydroxycinnamoyl esters in elicited parsley suspension cultures

Cell walls from suspension cultures of parsley (Petroselinum crispum L.) induced with a fungal elicitor contained hydroxycinnamoyl ester groups presumably not bound to pectic polysaccharides. Extracts from these cells were separated into a range of low-molecular-weight compounds containing esterified ferulic and p-coumaric acid as well as glucose and some arabinose. Similar compounds also accumulated extracellularly in elicited cultures but only in the presence of the peroxidase inhibitor ascorbate, suggesting that they may represent the exported precursors for cell wall hydroxycinnamic acids. From cultures elicited in the presence of ascorbate, alkali released from the cell walls more ferulic, p-coumaric and p-hydroxybenzoic acid, as well as p-hydroxybenzaldehyde and vanillin, indicating that the corresponding wall phenolics can all become further cross-linked.