The transient accumulation of phenylalanine ammonia-lyase (PAL) transcript was markedly induced in aged potato tuber slices 1 to 2hr after inoculation with an incompatible race of Phytophthora infestans, whereas the transcript in compatible interaction accumulated to lesser extent. A dramatic increase of PAL transcript accumulation occurred within 30min after treatment with hyphal wall components (HWC) of the pathogen, but the HWC-elicitor-stimulated increase was greatly suppressed by treatment with a suppressor from the compatible race. In contrast, treatment with HWC-elicitor in the presence of the suppressor from the incompatible race caused an acceleration of the accumulation of PAL mRNA compared with that with HWC-elicitor alone. These results for PAL transcript paralleled those based on the changes in PAL enzyme activity. Elicitation and suppression of induction of PAL transcript accumulation and PAL activity were discussed in relation to the race-cultivar specificity in potato late blight.