Wound wood formation in Eucalyptus globulus and Eucalyptus nitens: anatomy and chemistry

The wound-associated wood that developed 17 months following artificial xylem injury in Eucalyptus globulus (Labill) and Eucalyptus nitens (Maiden) was examined anatomically and chemically. This new tissue located immediately adjacent to the wound site and termed "wound wood" was highly variable consisting of callus, altered wood of increased parenchyma density, and dark extractives, visible to the naked eye. Subsequent chemical analysis of crude wound wood extracts by HPLC coupled to negative ion electrospray mass spectrometry revealed the presence of a diverse range of polyphenolic compounds including hydrolysable tannins, proanthocyanidins, flavanone glycosides, and formylated phloroglucinol compounds. A number of polyphenols were unequivocally identified including engelitin, pedunculagin, and tellimagrandin I. Other compounds present in wound wood include various hydroxystilbene glycosides and volatile terpenes. The importance of the diverse range of secondary metabolites detected in wound wood is discussed in relation to tree wound repair responses.