AN INDUCED PAPILLA RESPONSE IN PRIMARY ROOTS OF SCOTS PINE CHALLENGED INVITRO WITH CYLINDROCARPON-DESTRUCTANS

Cell wall appositions (papillae) were formed in the cortical and occasionally rhizodermal cells of primary roots of Pinus sylvestris L. that had been challenged in vitro with the root pathogen Cylindrocarpon destructans (Zins.) Scholt. Histochemical studies indicated that these papillae were composed predominantly of a matrix of pectic substances which was usually impregnated with polyphenolic or lignin-like materials. Proteins were also detected in the papillae. Elemental analysis of the papillae, using proton induced X-ray emission, indicated a higher concentration of calcium relative to normal cell walls. This result may reflect the high content of pectic materials in the papillae. In contrast to certain other plant species, no evidence was found for elevated silicon levels in pine papillae. Papillae appear to be involved in the resistance of pine primary roots to C. destructans. © 1991.