Production of steroidal alkaloids by hairy roots of Solanum aviculare and the effect of gibberellic acid |
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Authors: | M Ahkam Subroto Pauline M Doran |
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Institution: | (1) Department of Biotechnology, University of New South Wales, 2052 Sydney, NSW, Australia |
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Abstract: | Cultures of Solanum aviculare hairy roots were established after transformation with Agrobacterium rhizogenes A4. High levels of steroidal alkaloids measured as solasodine equivalents were produced in shake-flasks and bioreactor, even though relatively low concentrations are found 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 mg g-1. These yields represent a 5-fold increase over previous reports for in vitro production, and are comparable with levels found in the aerial parts of intact S. aviculare plants. Production of steroidal alkaloids was growth-associated. High sugar levels at stationary phase and insensitivity to increased levels of medium components suggest that root cultures were limited by oxygen mass-transfer. In Petri-dish culture with and without exogenous gibberellic acid, root length and number of root tips increased exponentially; growth proceeded with a constant length per root tip of about 35 mm. Addition of gibberellic acid enhanced growth but reduced the specific steroidal-alkaloid level. Taking into account both growth and alkaloid yield, accumulation of steroidal alkaloids was improved by about 40% at gibberellic-acid concentrations of 10 and 100 g l-1. |
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Keywords: | Agrobacterium rhizogenes gibberellic acid hairy root Solanum aviculare solasodine steroidal alkaloids |
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