FORMATION OF POLYPHENOLS IN TREES .4. POLYPHENOLS FORMED IN PINUS RADIATA AFTER SIREX ATTACK

The composition of the polyphenolic extractives of unattacked, damaged and Sirex-affected sapwood, heartwood and knotwood of Pinus radiata D. Don differ considerably. The sapwood contained vanillin, vanillic, protocatechuic, 4-hydroxybenzoic, salicylic and ferulic acids, hydroquinone, traces of pinosylvin monomethyl ether and unidentified compounds. The amounts of pinobanksin, pinocembrin, pinosylvin and its monomethyl ether are much greater in the knotwood than in the heartwood. Whereas only very small amounts of pinosylvin were found in heartwood, the amount in knotwood was larger than that of its ether. No flavonoids were found in Sirex-affected wood but the amount of pinosylvin was much larger than its ether. Damaged sapwood contained pinosylvin monomethyl ether and pinocembrin. A compound with the properties of a flavanolol C-glycoside was isolated from the heartwood and knotwood. It is concluded that wood extractives are formed in situ and that the conditions initiating their formation influence their composition. The restriction of the spread of the symbiotic fungus of Sirex in trees which resisted attack, appears to be due to the formation of stilbenes in the sapwood after infection. © 1968.