EFFECTS OF PLANT-GROWTH REGULATORS APPLIED TO THE ROOTS OF HYDROPONICALLY GROWN TAXUS X MEDIA PLANTS ON THE PRODUCTION OF TAXOL AND RELATED

Taxus x media cultivars/varieties (n = 14) (purchased from Heasley's N urseries, Butler, Pennsylvania) were screened for taxol, cephalomannin e, and 10-deacetyltaxol content in their needles and roots. Overall, t he mature roots of cv. Hicksii and var. Number 8 had the highest level s of taxol (424 and 427 mg/kg dry weight, respectively), while in the needles, the highest amounts were found in cv. Fieldii and var. Number 8 (231 and 249 mg/kg dry weight, respectively). Treating hydroponical ly grown cv. Hicksii plants with 100 mu M gibberellic acid (GA) or 100 0 mu M chlorocholine chloride (CCC) decreased root growth by approxima tely 38, and 22%, respectively, while treating with 100 mu M CCC incre ased root growth by 22%, compared to control plants. However, none of the treatments resulted in a greater than 9% increase in shoot growth compared to control plants, when evaluated over a 24 week period. Over all, the 100 mu M CCC treatment promoted the highest root mass, root-t o-shoot ratio, growth index, root volume, average root diameter, and t otal root length. The roots of plants treated with 1000 mu M CCC and 1 0 mu M ANC exhibited the highest amount of taxol, 332 +/- 32 and 334 /- 34 mg/kg on a dry weight basis, respectively, compared to control p lants (195 +/- 32 mg/kg). However, none of the treatments had dramatic effects on the amount of taxol, cephalomannine, or 10-deacetyltaxol i n needle and bark samples. In order to evaluate the overall effect of these treatments, the concentration of taxol, cephalomannine, and 10-d eacetyltaxol found in the roots need to be expressed as a Function of concentration and total root mass, because the different treatments si gnificantly affected only root growth. Accordingly, the highest amount s were found in the roots of the plants treated with 100 mu M CCC (430 mu g per plant, compared to 308 mu g per control plant). This increas e merely represents the increased root growth observed with the 100 mu M CCC treatment. CCC seems to have enhanced the process of secondary growth in the roots, as shown in scanning electron micrographs. Since the roots of plants treated with 100 and 1000 mu M CCC contained highe r concentrations of taxol, it appears that the process of secondary gr owth was responsible for the increase in taxol content. Copyright (C) Elsevier Science Ireland Ltd.