CHANGES IN PHENOLIC METABOLITES OF SCOTS-PINE PHLOEM INDUCED BY OPHIOSTOMA-BRUNNEO-CILIATUM, A BARK-BEETLE-ASSOCIATED FUNGUS

Changes in soluble phenol contents of Scots-pine (Pinus sylvestris) ph loem were studied after inoculation with Ophiostoma brunneo-cilatum, a fungus associated with Ips sexdentatus. They were compared to the len gth of the fungus-induced reaction zone of the phloem, taken as an est imation for the trees' response efficiency against aggression. Five cl ones consisting of 14 trees were studied, and eight soluble phenolic m etabolites were analysed in detail in reaction zones and in unwounded phloem sampled 3 weeks after inoculation. The stilbenes pinosylvin and pinosylvin monomethylether, and the flavonoid pinocembrin, were detec ted in reaction zones only. Concentrations of two p-coumaric-acid este rs and an acetophenone glycoside decreased after inoculation. Variatio ns of the flavonoids taxifolin and 3' taxifolin glucoside were inconsi stent. One tree had longer reaction zones and a phenolic content diffe rent from the others. In unwounded phloem, concentrations of some phen olic compounds and in particular the ratio between the two p-coumaric- acid esters could be markers for trees response efficiency. In the rea ction zone, markers could be the ratios between concentrations of cert ain preformed compounds and concentrations of newly synthesized pinosy lvin and pinocembrin.