Suspension cultures of Taxus cuspidata were challenged with various concentrations and combinations of methyl jasmonate and ethylene. Taxol productivity increased 19-fold when T. cuspidata suspension cultures were exposed to 5 ppm ethylene and 10 mu M methyl jasmonate. This increase was 15-fold when either 0 or 10 ppm ethylene was combined with 10 mu M methyl jasmonate. The induction of taxol occurred within 51 h after elicitation and would reduce fermentation times and costs. Ethylene concentration at 50 ppm had an inhibitory effect on taxol production but not on phosphate uptake rate, suggesting independent regulation of taxol and physiological functions of the cell. A simple induction model is proposed to explain the action and effects of both ethylene and methyl jasmonate with regard to receptor binding and regulatory systems in plants.