Abiotic factors elicit sesquiterpenoid phytoalexin production but not alkaloid production in transformed root cultures of Datura stramonium.

The treatment of root cultures of Datura stramonium with copper and cadmium salts at external concentrations of approximately 1mM has been found to induce the rapid accumulation of high levels of sesquiterpenoid defensive compounds, notably lubimin and 3-hydroxylubimin. These compounds were undetectable in unelicited cultures. No net change was seen in the alkaloid content of the system following treatment with Cu(2+) or Cd(2+), the tropane alkaloid titre apparently being insensitive to elicitation. However, a considerable rapid and, in some instances, reversible release of alkaloid was observed. This resulted in the appearance of up to 50-75% of the total alkaloid in the medium after 40-60 h. Subsequently, in cultures treated with Cu(2+) ions, though not in cultures treated with Cd(2+) ions, this alkaloid was re-absorbed. These observations show how, in a single system, different groups of secondary products can show distinct differences in their responses to potential elicitors.