Benzoic acid accumulation in the Pinus thunbergii callus inoculated with the pine wood nematode, Bursaphelenchus xylophilus.

Phenylacetic acid (PA), a phytotoxic product of the bacteria accompanying the virulent nematode isolate OKD-3 was detected in the callus of Pinus thunbergii after inoculation with the nematode. The amount of PA detected was large enough to induced the formation and accumulation of benzoic acid (BA) and its conjugates in the callus. These results further support the hypotheses that PA is the pathogenic toxin and that the PA-producing bacterial strains accompanying the pathogenic nematode are the genuine pathogens of the pine wilt disease.