CROWN GALL TUMORIGENESIS IN POTATO TUBER TISSUE

Abstract

Potato tuber discs were examined as a possible quantitative bioassay for studying tumor induction by Agrobacterium tumefaciens. Discs from two potato varieties, Pontiac and Russett Burbank, were inoculated and cultured on water agar plates. Tumors appeared within 10 days. Both the number and weight of tumors per disc increased linearly for inoculum concentration between 1 × 10⁷–1 × 10⁹ cells per ml. Polarity, position of the disc relative to tuber epidermis, potato variety and the light conditions did not influence the tumor formation. The simplicity of the procedure and the homogeneity of the tissue, together with the fact that it is a quantitative bioassay, makes the potato tuber disc an ideal system for the investigation of biochemical step(s) associated with the transformation process.