Expression of two genes of paclitaxel biosynthetic pathway during germination of Taxus baccata zygotic embryos

The spatial and temporal expression of dbat and dbtnbt genes involved in the later steps of paclitaxel biosynthesis in relation to baccatin III and paclitaxel accumulation in Taxus baccata L. germinating embryos and seedlings was investigated. The steady-state of mRNA transcripts was measured by quantitative real time polymerase chain reaction (qRT-PCR), the content of taxanes was determined by HPLC. The spatial distribution of the metabolites was found to be in accordance with the transcript level of the respective genes. Higher content of mRNA transcripts in shoots of yew seedlings responded to higher content of taxanes in stems and needles. The highest increase in the transcript level of both genes was observed 8 d after placing the embryos on germination medium, before elongation of embryonic axis and emergence of the radicle. The pattern of temporal dbat expression was in line with the expression of the dbtnbt gene. The temporal distribution of the precursor baccatin III correlated well with paclitaxel, the final product of the pathway.