Biochemical defence responses in primary roots of Scots pine challenged in vitro with Cylindrocarpon destructans

The occurrence of constitutive and induced antifungal compounds in primary roots of Pinus sylvestris seedlings was investigated, and total soluble phenols and lignification estimated, following challenge with the root pathogen Cylindrocarpon destructans. No reliably detectable phytoalexins were found, but the mean content of constitutive, antifungal diterpenic resin acids of the abietic acid group increased in the roots following infection. No diffuse lignitication was detected, but the content of cell-wall-bound phenolics increased with a concurrent decrease in the content of soluble phenols, although these changes were not statistically significant. The inhibitory effect of a commercial preparation of abietic acid on the germination of C. destructans spores was evaluated, and the significance of this class of compounds to defence in Scots pine seedlings is discussed.