Tissue‐specific study across the stem of Taxus media identifies a phloem‐specific TmMYB3 involved in the transcriptional regulation of paclitaxel biosynthesis

Abstract

SummaryTaxus stem barks can be used for extraction of paclitaxel. However, the composition of taxoids across the whole stem and the stem tissue‐specificity of paclitaxel biosynthesis‐related enzymes remain largely unknown. We used cultivated Taxus media trees for analyses of the chemical composition and protein of major stem tissues by an integrated metabolomic and proteomic approach, and the role of TmMYB3 in paclitaxel biosynthesis was investigated. The metabolomic landscape analysis showed differences in stem tissue‐specific accumulation of metabolites. Phytochemical analysis revealed that there is high accumulation of paclitaxel in the phloem. Ten key enzymes involved in paclitaxel biosynthesis were identified, most of which are predominantly produced in the phloem. The full‐length sequence of TmMYB3 and partial promoter sequences of five paclitaxel biosynthesis‐related genes were isolated. Several MYB recognition elements were found in the promoters of TBT, DBTNBT and TS. Further in vitro and in vivo investigations indicated that TmMYB3 is involved in paclitaxel biosynthesis by activating the expression of TBT and TS. Differences in the taxoid composition of different stem tissues suggest that the whole stem of T. media has potential for biotechnological applications. Phloem‐specific TmMYB3 plays a role in the transcriptional regulation of paclitaxel biosynthesis, and may explain the phloem‐specific accumulation of paclitaxel.

Floral organ-specific proteome profiling of the floral ornamental orchid (Cymbidium goeringii) reveals candidate proteins related to floral organ development

“…The TMT-labeled peptide solution was separated by a Pierce™ High pH Reversed Phase Peptide Fractionation column on an Agilent high-performance liquid chromatographer (HPLC) system. Thirty fractions were harvested for each sample and concatenated to 15 fractions for further analysis (Yu et al 2020 ).…”

The Taxus genome provides insights into paclitaxel biosynthesis

“…Moreover, studies have shown that jasmonates, gibberellin, auxin and ethylene are involved in the regulation of paclitaxel biosynthesis to maintain a delicate balance between growth and defence in Taxus [16][17][18] . Several transcription factors (TFs), including AP2/ERF, WRKY, MYC and MYB, have been found to regulate the expression of paclitaxel biosynthetic genes [19][20][21] . However, the comprehensive regulatory mechanisms underlying the growth-defence trade-off are still poorly understood.…”

Omic analysis of the endangered Taxaceae species Pseudotaxus chienii revealed the differences in taxol biosynthesis pathway between Pseudotaxus and Taxus yunnanensis trees

“…Differenially expressed MYC TFs might play an important role in taxol biosynthesis. Interestingly, a phloemspecific TmMYB3 was reported to be involved in the transcriptional regulation of paclitaxel biosynthesis [55]. Recently, expression profiling and posttranscriptional regulation of the R2R3-MYB TF family in T. chinensis have been well analyzed [56].…”