Cardenolides inDigitalis lanataCells Transformed with Ti-Plasmids

Abstract

Crown galls were induced by transformation of leaves, leaf discs, and shoots of the plant Digitalis lanata with the Agrobacterium tumefaciens strains C58 pTi C58, B6S3 pTi B6S3, and A136 pTi A6NCtmr-338::Tn5. Integration of plasmid DNA in the genome of D. lanata was demonstrated by hybridization experiments. The transformed cells synthesized opines and showed hormone-autotrophic growth. The crown galls formed on leaves of D. lanata plants contained digitoxigenin derivatives (up to 0.8 μimol digitoxin equivalents g^-1 dry weight). Transformed cell lines derived from the crown galls built cardenolides in vitro (ca. 0.03 μmol digitoxin equivalents g^-1 dry weight). The rate of cardenolide biosynthesis in vitro did not decrease during a cultivation period of 12 months.