ACTINOMYCIN D INDUCTION OF TERPENE STRESS METABOLITES IN POTATO TUBER SLICES

Relatively large amounts of rishitin and lubimin accumulate in potato tuber slices following treatment with actinomycin D (AD). Optimum elicitation of these terpenes occurred at an (AD) concentration of μM. Terpene accumulation was evident within 24 h after treatment and progressed for up to 96 h at which time rishitin levels exceeded 100 μg/g fresh weight, discs. Slices prepared from tubers previously held at 25°C were less responsive to (AD) induction of terpenes than those from tubers previously stored at 4°C. Treatment of discs with 50 μM cycloheximide following (AD) treatment blocked further accumulation of terpenes indicating a requirement for continual protein synthesis. (AD) (20 μM) treatment caused a slight reduction in protein synthesis for the first 48 h following treatment after which it caused an increase in protein synthesis compared to controls. (AD) also affected respiration of discs in a manner which paralleled its effect on protein synthesis. Cyanide resistant respiration was more pronounced in (AD) treated discs than control discs. The data are discussed with reference to the mechanism by which (AD) elicits terpene biosynthesis in potato tubers discs.