Alkaloid Production by Transformed Root Cultures of Cinchona ledgeriana

Abstract

Transformed root cultures of Cinchona ledgeriana have been generated by infecting shoots cultured in vitro with Agrobacterium rhizogenes LBA9402. These root cultures grow axenically in the absence of antibiotics or exogenous plant growth regulators in media containing Gamborg B5 salts at half or full strength with 3% (w/v) sucrose as the carbon source. They show a 6- to 8-fold increase in fresh weight in 28 days. Transformation has been confirmed by Southern blotting using [³² P]-labelled fragments from both the T _L - and T _R -DNA of the Ri plasmid. The cultures are shown to synthesise a range of quinoline alkaloids, of which quinine, cinchonidine, and quinidine are the major components. The level of these alkaloids changes with the age of the cultures, reaching a maximum at about 50 µg/g fresh weight after 45 days. In addition, the roots contain quinamine and a number of other, unidentified, indole alkaloids, one of which is the major alkaloid present. Only about 1% of the total alkaloid present is released to the medium.