Wound-induced traumatic resin duct development in stems of Norway spruce (Pinaceae): Anatomy and cytochemical traits

Wounding of Norway spruce by inoculation with sterile agar, or agar contain ing the pathogenic fungus Ceratocystis polonica, induced traumatic resin du ct formation in the stem. Visible anatomical responses occurred in the camb ium 6-9 d post-inoculation. Near the inoculation site cellular proliferatio n, polyphenolic accumulation, and Lignification were induced as a wound rea ction to seal the damaged area. Five centimetres from the inoculation site cells in the cambial zone swelled and divided to form clusters. By 18 d pos t-inoculation, these cells began to differentiate into resin duct epithelia l cells surrounding incipient schizogenous lumens. Mature axial traumatic d ucts appeared by 36 d as a row of ducts in the xylem centripetal to the cam bium. The ducts formed an interconnected network continuous with radial res in ducts. Parenchyma cells surrounding the ducts accumulated polyphenols th at disappeared as the cells differentiated into tracheids. These polyphenol s appeared to contain fewer sugar residues compared to those accumulating i n the secondary phloem, as indicated by the periodic acid-Schiff's staining . The epithelial cells did not accumulate polyphenols but contained immunol ogically detectable phenylalanine ammonia lyase (EC 4.3.1.5), indicating sy nthesis of phenolics as a possible resin component. These findings may repr esent a defense mechanism in Norway spruce against the pathogenic fungus Ce ratocystis polonica.