Composition of callus resin of Norway spruce, Scots pine, European larch and Douglas fir

Abstract

Abstract On damage of conifer trees, oleoresin is exuded onto the tree stem. The oleoresin is typically composed of monoterpenes and resin acids. It serves to protect the tree from dehydration and microbial attack. Callus resin, in the traditional German term “Überwallungsharz”, is a resin exuded from the callus tissue formed as the wound is closed by annual growth. These resins can usually be found as nodules or lumps on the rim of the closing wound. Both types of resin, collected from Picea abies, Pinus sylvestris, Larix decidua and Pseudotsuga menziesii, were analyzed separately by GC/GC-MS. Expectedly, the oleoresin samples were composed of resin acids. However, the callus resins were of a completely different composition as they are composed primarily of lignans and hydroxycinnamic acid derivatives. In addition, the L. decidua sample contained significant amounts of abietol and abietadiene. The P. abies and L. decidua callus resins were found to be essentially resin acid-free. The components identified in the callus resin samples have previously been identified as minor components in oleoresin and bark samples. The potential for the inadvertent inclusion of callus resin in previously analyzed samples of oleoresin, bark and ingrown (dead) knots is highlighted.