Induction of Rishitin and Lubimin Synthesis in Potato Tuber Slices by Non-Specific Elicitors - Role of Gene Derepression.

The stress metabolites rishitin and lubimin accumulate at relatively low concentrations (5-20 ppm) in potato tuber slices subjected to various cell-disruptive treatments including heavy metal salts, sulfhydryl reagents, metabolic inhibitors, detergents, ultraviolet light and lysosomal enzymes. Cold-stored (4 C) tubers are more disposed to terpene accumulation than freshly harvested, 25-C stored and conditioned potatoes. Various inhibitors of DNA transcription and mRNA translation block terpene induction by non-specific elicitors when applied at sufficiently high concentration. However. various protein synthesis inhibitors were shown to be potent elicitors of terpene accumulation when applied at lower concentration. Actinomycin D (25 μg/ml) treatment of discs for 30 min elicits higher levels of rishitin than results from Phytophthora infestans interaction with potato (> 100 ppm). A mechanism for terpene induction based on derepression of "stress metabolite DNA" is proposed to explain the experimental data.