Abstract
Spectrophotometer, paper chromatography, and liquid chromatography were used to isolate and characterize the substances associated with tissue browning of Japanese red pine, (Pinus densiflora) and Japanese black pine (P. thunbergii) inoculated withBursaphelenchus xylophilus or B. mucronatus. Discoloration, as determined by optical density, and numbers of B. xylophilus was highest near the inoculation site and decreased with increasing distance from that point. Absorption spectra of water extracts from pines infected with B. xylophilus had a distinct peak at 278 nm. The absorption at 278 nm decreased when the extract was oxidized and shifted to 287 nm when 1N NaOH was added, suggesting that the extract contained polyphenolic substances. The increase in browning with increase in nematode population indicates that these substances were related to the nematode infection. B. xylophilus-inoculated seedlings contained much greater amounts of phenolics than B. mucronatus-inoculated and control seedlings. A catechin-like substance was the most abundant polyphenolic associated with large numbers of B. xylophilus. Changes in the amount of condensed tannin, the polymer of catechin, were surveyed in relation to the numbers of nematodes in pine seedlings. Jpn. J. Nematol. 33 (2), 45-56 (2003).
