-Fernie and coworkers further demonstrated the accumulation of paclitaxel in tobacco leaves by co-expressing additional enzymes involved in side-chain assembly and modification, along with supplementation of precursors like benzoic acid, L-phenylalanine, and baccatin III. -T5αH, the first cytochrome P450 enzyme in the pathway, exhibits promiscuous activity when expressed in heterologous hosts such as *Escherichia coli*, *Saccharomyces cerevisiae*, and *N. benthamiana* .