Pc. Evensen et al., Induced resistance of Norway spruce, variation of phenolic compounds and their effects on fungal pathogens, FOREST PATH, 30(2), 2000, pp. 97-108
Three clones of Norway spruce (Picea abies) were studied for their response
to mass-inoculation with the blue-stain fungus Ceratocystis polonica. The
effect of different pretreatments (fungal inoculation and wounding) before
mass-inoculation was investigated for their possible role in an acquired re
sistance reaction. Pretreated trees showed enhanced resistance to the subse
quent mass-inoculation relative to control trees that received no pretreatm
ent. Furthermore, the fungal colonization of inoculated trees was less than
that of wounded trees. The phenolic content of the bark, analysed by RP-HP
LC, was compared in trees receiving different treatments. Trees inoculated
with C. polonica had higher average concentration of (+)-catechin, taxifoli
n and trans-resveratrol than wounded trees. Both inoculated and wounded tre
es had higher average concentrations of these compounds than control trees.
The effect of the phenolic extract of Norway spruce bark on the growth of
the root rot fungus Heterobasidion annosum and the blue-stain fungi C, polo
nica and Ophiostoma penicillatum were investigated in vitro. Heterobasidion
annosum was not negatively affected, and the extracts had fungistatic effe
cts on the blue-stain fungi. The growth of O. penicillatum was more inhibit
ed than the growth of the more aggressive C. polonica.