Competition between phenylpropanoid and antrhaquinone pathways in Rubia tinctorum cell suspensions

PARSONS, JULIANA; HOSCHT, CRISTIAN; ZON, JERZY; GIULIETTI, ANA M. AND RODRIGUEZ TALOU, JULIÁN.

Santiago de Chile, chile

Congreso; 12th International Biotechnology Symposium; 2004

It has been demonstrated that the addition of  proline or its analogue azetidine-2-carboxilate (A2C) deregulate proline synthesis in plants. This deregulated biosynthetic proline pathway leads to an overexpressed  pentose phosphate pathway (PPP) which results in a increasing carbon flux through the shikimate pathway via erythrose-4-phosphate. The stimulation of shikimate pathway produced an increase in phenylpropanoid related secondary metabolites (phenolics) in several plant in vitro cultures [1] Chorismate, which is the end product of the shikimate pathway, becomes the branch point for the synthesis of phenylpropanoid and anthraquinones (AQs) in Rubia tinctorum secondary metabolism. In this preliminary work we tested the effect of proline addition in plant suspension cultures of R. tinctorum in order to study the competition between the two above mentioned secondary metabolic pathways. Plant suspension cultures were treated with  proline at different concentrations, 0.25, 5 and 25 mM. An slightly increase of AQs was observed at 0.25 mM, while higher amounts of proline ( 5 and 25 mM) showed a significant decrease of 35 % an 50 % on AQs accumulation and an increase in phenolics concentration. The addition of the phenylalanine ammonia liase inhibitor [2], 2-aminoindan-2-phosphonic acid (AIP), at 40 and 100 mM resulted in an increase of AQs concentration in suspension cultures of 18 and 40 % respectively. These results show that is possible to increase AQs production at expense of the phenylpropanoid pathway in Rubia tinctorum suspension cultures. [1] Shetty, K. (2003) Process Biochemistry, 39:789-804. [2] Appert, C. et al. (2003) Phytochemistry 62:415-422.