THE FORMATION OF PINOSYLVIN AND ITS MONOMETHYL ETHER IN THE SAPWOOD OF PINUS RESINOSA AIT.

Abstract

Mechanical damage to bark and cambium of red pine (Pinus resinosa Ait.), as well as fungal penetration of sapwood in the interior of roots and stems, induces the formation of heartwood substances in the affected parts of the sapwood. Paper chromatography disclosed the occurrence of pinosylvin (trans-3,5-dihydroxy-stilbene) and its monomethyl ether (3-hydroxy-5-methoxy-stilbene) in affected sapwood. Normal undamaged sapwood does not contain these substances, which were found to be restricted to the heartwood, except for pinosylvin monomethyl ether, which was found to occur also in the pith of branches.Field and laboratory experiments were carried out on the local formation of pinosylvins in the sapwood of live branches of red pine following wounding of the cambium. It was found that the pinosylvins are formed in the late part of the growing season and during the dormant season. Cross sections through the wound on branches showed the pinosylvins in a triangular pattern with the wounded cambium as a base line and the other two sides of the triangle extending along the rays to the pith.Cells killed rapidly did not form pinosylvins. However, cells dying slowly, and in the laboratory experiments under the influence of desiccation, produced both pinosylvin and its monomethyl ether. The optimum production of the pinosylvins occurred in the laboratory at approximately 25 °C, while no production was found at 35 °C and higher temperatures.It is concluded that the pinosylvins are formed by living cells in the sapwood under the influence of desiccation and/or aeration and that their formation is a defense reaction against attack by pathogens.The term "protection wood" is preferred as an alternative term for "pathological heartwood" or "mineral stain", which has been used by many authors.