Bark removal and population structure of Taxus wallichiana Zucc. in a temperate mixed conifer forest of western Himalaya

Quantification of Tissue-Specific Paclitaxel in Himalayan Yew Using HPTLC-Densitometric Analysis, Assessment of Toxicological Activity, and Tissue-Specific Evaluation of Antioxidant Activity

Taxus wallichiana Zucc., commonly known as the Himalayan Yew, is currently experiencing endangerment due to excessive harvesting and sluggish growth resulting from the extraction of paclitaxel, a crucial plant-derived medication employed in the treatment of cancer. T. wallichiana contains various phytochemicals, including paclitaxel, a diterpenoid that has been utilized as an anticancer medication. In order to extract paclitaxel while maintaining the species' survival, it is difficult to determine the most effective plant parts. We determined the diterpenoid paclitaxel content using modern analytical methods such as high-performance thin-layer chromatography-densitometric analysis. Furthermore, toxicological evaluations were carried out and tissue-specific antioxidant activity was statistically analyzed using 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP), Folin-Ciocâlteu (FC), and 2,2-diphenyl-β-picrylhydrazyl (DPPH) assays. The results of our study offer significant contributions to the identification of optimal plant components for the extraction of paclitaxel. This information is crucial in the conservation of T. wallichiana and in mitigating the difficulties associated with its threatened classification. The present investigation makes a valuable contribution toward the advancement of sustainable methodologies in the manufacturing of paclitaxel, as well as the preservation of T. wallichiana for posterity. Bark exhibited the maximum paclitaxel yield at a content of 29162.3 μg/g dry weight. The accuracy of the method has been validated in accordance with the guidelines outlined by the International Council for Harmonisation (ICH). The current investigation evaluated the potential cytotoxic and genotoxic effects of the aqueous extracts on meristematic cells from the roots ofAllium cepa. The extracts obtained from the bark exhibited noteworthy cytotoxic and mitotic characteristics. The current investigation holds potential significance for the pharmaceutical sector in terms of identifying superior chemotypes of T. wallichiana that produce high levels of paclitaxel. Conducting a toxicological assessment on various tissues of T. wallichiana chemotypes through employment of the Allium cepa test would facilitate the identification of any potential genotoxic characteristics. The present study aimed to investigate four distinct assays, namely, DPPH, ABTS, FRAP, and FC, for the evaluation of the antioxidant potential of diverse T. wallichiana plant extracts and standard substances. The findings suggest that FRAP and ABTS exhibit a strong correlation. In general, the entirety of the tissue extract exhibited commendable antioxidant capacity, thereby rendering it a promising contender for diverse applications.

Integrated mass spectrometry imaging and single-cell transcriptome atlas strategies provide novel insights into taxoid biosynthesis and transport in Taxus mairei stems

Taxol, which is a widely used important chemotherapeutic agent, was originally isolated from Taxus stem barks. However, little is known about the precise distribution of taxoids and the transcriptional regulation of taxoid biosynthesis across Taxus stems. Here, we used MALDI-IMS analysis to visualize the taxoid distribution across Taxus mairei stems and single-cell RNA sequencing to generate expression profiles. A single-cell T. mairei stem atlas was created, providing a spatial distribution pattern of Taxus stem cells. Cells were reordered using a main developmental pseudotime trajectory which provided temporal distribution patterns in Taxus stem cells. Most known taxol biosynthesis-related genes were primarily expressed in epidermal, endodermal, and xylem parenchyma cells, which caused an uneven taxoid distribution across T. mairei stems. We developed a single-cell strategy to screen novel transcription factors (TFs) involved in taxol biosynthesis regulation. Several TF genes, such as endodermal cell-specific MYB47 and xylem parenchyma cell-specific NAC2 and bHLH68, were implicated as potential regulators of taxol biosynthesis. Furthermore, an ATP-binding cassette family transporter gene, ABCG2, was proposed as a potential taxoid transporter candidate. In summary, we generated a single-cell Taxus stem metabolic atlas and identified molecular mechanisms underpinning the cell-specific transcriptional regulation of the taxol biosynthesis pathway.

Quick and In Situ Detection of Different Polar Allelochemicals in Taxus Soil by Microdialysis Combined with UPLC-MS/MS

The action of allelopathy need that allelochemicals exist in the soil and reach a certain concentration. Also, the detection of allelochemicals in the soil is one of the most important research topics in the process of exploring allelopathy. To solve the problem of the simultaneous detection of allelochemicals with low concentrations and different polarities, a novel strategy for the quick detection of the allelochemicals in Taxus soil by microdialysis combined with UPLC-MS/MS on the basis of in situ detection without destroying the original structure of soil was developed for the first time in the work. The dialysis conditions were optimized by the Box-Behnken design (BBD): 70% methanol, 3 μL/min flow rate, and 3 cm long membrane tube. A reliable UPLC-MS/MS program was systematically optimized for the simultaneous detection of nine allelochemicals with different polarities. The results proved the differences in the contents and distributions of nine allelochemicals in three different Taxus soils.

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

Taxus 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.

The effect of management systems and ecosystem types on bark regeneration in Himatanthus drasticus (Apocynaceae): recommendations for sustainable harvesting

Bark and exudates are widely commercialized non-timber forest products. However, the ecological impacts of the harvesting of these products have seldom been studied. The aim of this study is to investigate the relationship of tree resilience to harvesting intensity in Himatanthus drasticus, a tree that is highly exploited in the Brazilian savanna (Cerrado) for its medicinal latex. Although the traded product is the latex, the traditional harvesting systems involve the removal of the bark of the trees to allow exploitation. A 3-year experiment was conducted in two different Cerrado ecosystems (open savanna and savanna woodland). Trees were debarked at four debarking intensities to simulate the effects of traditional management systems. Measurements of bark growth were taken every 6 months, and quantitative and qualitative indexes of bark regeneration were obtained. The mortality of the debarked trees was low and could not be related to the intensity of harvesting. No signs of attack by fungi or insects were recorded. Compared with other species exploited for bark, H. drasticus is very resilient to harvesting; however, bark regeneration is relatively slow. In both analyzed ecosystems, the regeneration indexes showed higher values in the controls than in the treatments, indicating that 3 years is not sufficient for total recovery of the rhytidome. Bark regeneration occurred primarily by sheet growth and was more rapid in open savanna than in savanna woodland. No differences in the rate of bark recovery were found among management treatments. Based on the results, sustainable harvesting guidelines are suggested for the species.