Effects of sodium orthovanadate on benzophenanthridine alkaloid formation and distribution in cell suspension cultures of Eschscholtzia californica

Cell suspension cultures of Eschscholtzia californica produce relatively la rge amounts of benzophenanthridine alkaloids upon elicitation. Sodium ortho vanadate is used as an abiotic elicitor to induce alkaloid biosynthesis in cultures of E. californica. The response of the cell culture to this abioti c elicitor is very similar to that observed after elicitation with a biotic elicitor (a carbohydrate fraction from yeast extract). Treatment with orth ovanadate leads to alkalinization of the growth medium, a 20-fold induction of the key enzyme tyrosine decarboxylase and increased alkaloid formation (up to 40 mg.L-1). Cells treated with the yeast elicitor excrete a large po rtion of alkaloids produced into the growth medium (up to 50% of total alka loids) while cells treated with orthovanadate release very small amounts of alkaloids into the medium (less than 10% of total alkaloids). These result s suggest that an active transport system, possibly specific for benzophena nthridine alkaloids, is present in the plasma membrane of E. californica ce lls. The nature of this putative vanadate-sensitive transporter is not know n at present. (C) 2000 Editions scientifiques et medicales Elsevier SAS.