ABSTRACT
Objective: The callus induction and subculture condition of Taxus chinensis var. mairei were optimized in the experiment. High Taxol-yielding callus was obtained, and the correlation between expression patterns of Taxol biosynthesis related genes and Taxol content was defined. Methods: Optimal hormone composition and concentration for induction and subculture of callus derived from T. chinensis var. mairei were briefly studied. The growth characteristics and Taxol content of calli derived from T. chinensis var. mairei (including vitro embryos, juvenile stems, and juvenile buds), T. media (vitro embryos) and T. brevifolia (vitro embryos) were compared. Expression of Taxol biosynthesis related genes in the above different calli was analyzed. Results MS Medium supplemented with 3.0 mg/L 2,4-D was suitable for callus induction of T. chinensis var. mairei, the induced rate is up to 92%. Subculture medium supplemented with 2.0 mg/L 2,4-D and 1.0 mg/L 6-BA was suitable for Taxol biosynthesis of T. chinensis var. mairei. Under the same culture conditions, Taxol content of calli derived from vitro embryos of T. chinensis var. mairei was the highest and had reached 0.027% of callus dry weight. The genes of Taxol biosynthesis related enzymes - geranylgeranyl diphosphate synthase (GGPPS), taxadiene synthase (TASY), taxane-10β-hydroxylase (T10βH), 10-deacetylbaccatin III-β-10-O-acetyltransferase (DBAT), phenylalanine aminomutase (PAM), and 3′-N-debenzoyltaxol N-benzoyltransferase (DBTNBT), were expressed at the high level in the high Taxol-producing callus. Conclusion: Vitro embryos can be used as the first choice expiant source to obtain high Taxol-yielding callus. To improve gene expression level of GG-PPS, TASY, T10βH, DBAT, PAM, and DBTNBT would promote Taxol biosynthesis.
ABSTRACT
Object To study the effect of pH on callus tissue growth and paclitaxel content of Taxus cuspidata Sieb. et Zucc. and Taxus chinensis var. mairei (Lemee et Le ′vl.) Cheng et L. K. Fu Methods The callus tissues were cultured on B5 medium with defferent pH values, and the growth rate, PAL activity and paclitaxel content were determined. Results Different callus tissues of taxus need different optimum pH values. The pH values, which could promote callus growth significantly, were all inhabitory to PAL activity and accumulation of paxlitaxel. Conclusion pH had great influences on the growth of the callus and the level of secondary metabolism, thereby the synthesis and accumulation of paclitaxel were affected.