PRODUCTION OF STEROIDAL ALKALOIDS BY HAIRY ROOTS OF SOLANUM AVICULAREAND THE EFFECT OF GIBBERELLIC-ACID

Cultures of Solanum aviculare hairy roots were established after trans formation with Agrobacterium rhizogenes A4. High levels of steroidal a lkaloids measured as solasodine equivalents were produced in shake-fla sks and bioreactor, even though relatively low concentrations are foun d in roots in vivo. In shake flasks the maximum alkaloid yield was 32 mg g(-1) dry weight; in a 3-1 air-driven bioreactor the yield was 29 m g g(-1). These yields represent a 5-fold increase over previous report s for in vitro production, and are comparable with levels found in the aerial parts of intact S. aviculare plants. Production of steroidal a lkaloids was growth-associated. High sugar levels at stationary phase and insensitivity to increased levels of medium components suggest tha t root cultures were limited by oxygen mass-transfer. In Petri-dish cu lture with and without exogenous gibberellic acid, root length and num ber of root tips increased exponentially; growth proceeded with a cons tant length per root tip of about 35 mm. Addition of gibberellic acid enhanced growth but reduced the specific steroidal-alkaloid level. Tak ing into account both growth and alkaloid yield, accumulation of stero idal alkaloids was improved by about 40% at gibberellic-acid concentra tions of 10 and 100 mu g l(-1).