Explore the vast range of titles available.

Tropane alkaloids (TAs) are heterocyclic nitrogenous metabolites found across seven orders of angiosperms, including Malpighiales (Erythroxylaceae) and Solanales (Solanaceae). Despite the well-established euphorigenic properties of Erythroxylaceae TAs like cocaine, their biosynthetic pathway remains incomplete. Using yeast as a screening platform, we identified and characterized the missing steps of TA biosynthesis in Erythroxylum coca. We first characterize putative E. coca polyamine synthase- and amine oxidase-like enzymes in vitro, in yeast, and in planta to show that the first tropane ring closure in Erythroxylaceae occurs via bifunctional spermidine synthase/N-methyl-transferases and both flavin- and copper-dependent amine oxidases. We next identify a SABATH family methyltransferase responsible for the 2-carbomethoxy moiety characteristic of Erythroxylaceae TAs and demonstrate that its coexpression with methylecgonone reductase in yeast engineered to express the Solanaceae TA pathway enables the production of a hybrid TA with structural features of both lineages. Finally, we use clustering analysis of Erythroxylum transcriptome datasets to discover a cytochrome P450 of the CYP81A family responsible for the second tropane ring closure in Erythroxylaceae, and demonstrate the function of the core coca TA pathway in vivo via reconstruction and de novo biosynthesis of methylecgonine in yeast. Collectively, our results provide strong evidence that TA biosynthesis in Erythroxylaceae and Solanaceae is polyphyletic and that independent recruitment of unique biosynthetic mechanisms and enzyme classes occurred at nearly every step in the evolution of this pathway.

Anisodus tanguticus is a valuable plant for extracting tropane alkaloids. However, the mechanisms by which plant microbiome mediate the accumulation of tropane alkaloids in Anisodus tanguticus are still not well understood. In this study, we collected 55 wild Anisodus tanguticus populations on the Tibetan Plateau and the tropane alkaloids content, and root-related bacteria and fungi diversity were analyzed using HPLC and 16 s rDNA and ITS sequencing. The results showed that tropane alkaloids content has obvious geographical distribution characteristics. Anisodine content had a significant positive correlation with latitude, while anisodamine and atropine content had a significant negative correlation with latitude. Variation partition analysis (VPA) showed that root endophytes play a significant role in promoting tropane alkaloid production in Anisodus tanguticus roots. The root endophytes alone explained 14% of the variation, which was the largest contributor. Soil properties variables could independently explain 5% of the variation, and climate variables could explain 1% of the variation. Of these, endophytic fungi alone accounted for 11%, while bacteria explained only 5%. Random forests and Mantel test showed that different regionally enriched endophytic fungi have a greater impact on the accumulation of tropane alkaloids than the whole endophytic fungi. Richness and relative abundance of enriched endophytic fungi in Hengduan-Qilian Mountains (HQ) group has a significant positive correlation with anisodine content, while richness and relative abundance of enriched endophytic fungi in Himalayas-Hengduan Mountains (HH) group has a significant positive correlation with anisodamine and atropine content. And, these enriched endophytic fungi have high network connectivity and distributed in separate network modules. This study further confirmed that endophytes were closely related to tropane alkaloids accumulation in Anisodus tanguticus and contribute to promote sustainable development, cultivation, and precision medicine of Anisodus tanguticus.

Background Although it is well recognized that core root microorganisms contribute to plant health and productivity, little is known about their role to the accumulation of secondary metabolites. The roots of Anisodus tanguticus , a traditional herbal medication utilized by Tibetan medicine, are rich in tropane alkaloids. We collected wild A. tanguticus populations throughout a 1500 km transect on the Qinghai-Tibetan Plateau. Results Our results showed that despite sampling at a distance of 1500 km, the root of A. tanguticus selectively recruits core root bacteria. We obtained 102 root bacterial core OTUs, and although their number only accounted for 2.99% of the total, their relative abundance accounted for 73% of the total. Spearman correlation and random forest analyses revealed that the composition of core root microbiomes was related to anisodine contents, aboveground biomass and nitrogen contents of Anisodus tanguticus . Among them, the main role is played by Rhizobacter , Variovorax , Polaromonas , and Mycobacterium genus that are significantly enriched in roots. Functional prediction by FAPROTAX showed that nitrogen-cycling microorganisms and pathogenic bacteria are strongly associated with anisodine contents, aboveground biomass and nitrogen contents of Anisodus tanguticus . Conclusions Our findings show that the root selectively recruits core root bacteria and revealed that the core microbiomes and microbial functions potentially contributed to the anisodine contents, aboveground biomass and nitrogen contents of the plant. This work may increase our understanding of the interactions between microorganisms and plants and improve our ability to manage root microbiota to promote sustainable production of herbal medicines.

The belladonna plant, Atropa belladonna L. (Solanaceae), is the most important commercial source of tropane alkaloids such as atropine and scopolamine used for medicinal and pharmaceutical purposes. The chemical biosynthesis and extraction of tropane alkaloids using wild-collected plants has been demonstrated to be difficult, prolong and commercially unachievable. Therefore, this study investigated the combinational impact of different (1) leaf sterilization treatments [mercuric chloride (HgCl 2 ) (0.1–0.3%), sodium hypochlorite (NaOCl) (20–40%), thiophanate-methyl (fungicide) (10–30%)] on viability, clean explants, and contamination %, (2) 2-isopentenyladenine (2-iP) (2–3 mg/L) + 2,4-dichlorophenoxyacetic acid (2,4-D) (2–6 mg/L) on callus induction % and fresh weight (FW), and (3) 2-iP + 2,4-D + 1–3 mM ornithine on dry weight (DW), atropine and scopolamine content in in vitro cell suspension cultures of A. belladonna . The 0.1% HgCl 2  + 30% thiophanate-methyl + 40% NaOCl sterilization treatment was the most effective (100% disinfection, 70% viability). Maximized callus induction (100%) and FW were recorded in MS medium containing 3 mg/L 2-iP + 2 mg/L 2,4-D (4 weeks) and 2 mg/L 2-iP + 5 mg/L 2,4-D (2 months), respectively. DW and scopolamine (4.33 mg/g), and atropine (4.14 mg/g) content were higher in liquid medium with 3 mg/L 2-iP + 3 mg/L 2,4-D + 1 or 3 mM ornithine, respectively (10 weeks). In vitro production of atropine and scopolamine in cell suspension cultures of A. belladonna in shake flasks can be increased and accelerated using elicitors such as plant growth regulators ( i.e., 2-iP, 2,4-D) and amino acids precursors ( i.e., ornithine) involved in alkaloids biosynthetic pathway.

Ornithine decarboxylase (ODC) is the rate-limiting enzyme in the biosynthesis of polyamines and plant alkaloids, including medicinal tropane alkaloids (TAs). Due to its key role, ODC has been utilized as an effective molecular tool in metabolic engineering. However, to date, only a limited number of plant ODCs have been characterized. Among the reported ODCs, Erythroxylum coca ODC (EcODC) exclusively has ODC activity, while Nicotiana glutinosa ODC (NgODC) exhibits dual ODC and lysine decarboxylase (LDC) activities. The potential LDC activity of ODCs from TA-producing plants remains unknown. Here, we characterized AlODC and DsODC from Anisodus luridus and Datura stramonium, along with two previously reported ODCs from Atropa belladonna (AbODC) and Hyoscyamus niger (HnODC), in Escherichia coli to investigate their enzyme kinetics and substrate specificity. Enzymatic assays revealed that both AlODC and DsODC catalyzed the conversion of ornithine to putrescine, confirming their ODC activity, with AlODC exhibiting a higher catalytic efficiency, comparable to established ODCs. Furthermore, all four ODCs also displayed LDC activity, albeit at significantly lower efficiency (<1% of ODC activity). This study provides a comprehensive analysis of the enzyme kinetics of ODCs from TA-producing plants, identifying promising candidate genes for metabolic engineering for the biomanufacturing of putrescine-derived alkaloids. Moreover, this is the first report of LDC activity in ODCs from Solanaceae TA-producing plants, shedding light on the evolutionary relationship between ODC and LDC.

Datura stramonium L. produces tropane alkaloids, and the hyoscyamine is dominant among them. Hyoscyamine is produced by hairy root cultures in vitro derived from native plants or plants with the genetically modified biosynthetic pathway for hyoscyamine. A common procedure is extraction from cultivated plants. Elicitors for increased production can be used in both cases. Live viruses are not well known for use as elicitors, therefore, D. stramonium plants grown in soil were artificially infected with the tobamoviruses Pepper mild mottle virus (PMMoV), Tomato mosaic virus (ToMV), and Tobacco mosaic virus (TMV). Differences in the content of hyoscyamine were between capsules and roots of infected and non-infected plants. Elicitation increased content of hyoscyamine in capsules 1.23–2.34 times, compared to the control. The most effective viruses were PMMoV and ToMV (isolate PV143), which increased content to above 19 mg/g of fresh weight of a capsule. The effect of each virus elicitor was expressed also in hyoscyamine content in roots. Elicited plants contained 5.41–16.54 times more hyoscyamine in roots compared to non-elicited plants. The most effective elicitor was ToMV SL-1, which raised production above 20 mg/g fresh weight of roots. It has been shown that tobamoviruses can be used as biotic elicitors.

Recent research progress on the “second generation” type III polyketide synthases is summarized. This class of enzymes catalyzes unusual condensation chemistries of CoA thioesters to generate various core structures of medicinally important plant secondary metabolites, including the R 1 –C–R 2 scaffold of alkyl quinolones, curcuminoids, as well as the 8-azabicyclo[3.2.1]octane ring of tropane alkaloids. The discovery of this fascinating enzyme superfamily provides excellent opportunities for the manipulation of the enzyme reactions to expand the supply of natural and unnatural molecules for future drug development.

The European Food Safety Authority (EFSA) was asked to deliver a scientific opinion on the risks to human and animal health related to the presence of tropane alkaloids (TAs) in food and feed. TAs are secondary metabolites which occur in several plant families. Although more than 200 different TAs have been identified in various plants, respective data on toxicity and occurrence in food and feed are limited. Therefore, the EFSA Panel on Contaminants in the Food Chain (CONTAM Panel) could only perform a risk assessment on (‐)‐hyoscyamine and (‐)‐scopolamine, the two TAs for which occurrence and toxicity data were available. Since the pharmacological effects of (‐)‐hyoscyamine and (‐)‐scopolamine occur within a short time after administration, the CONTAM Panel concluded that it was appropriate to establish an Acute Reference Dose (ARfD) for these substances. Based on the results for decreased heart rate in a human volunteer study, the CONTAM Panel established a group ARfD of 0.016 μg/kg body weight (b.w.) expressed as the sum of (‐)‐hyoscyamine and (‐)‐scopolamine, assuming equivalent potency. Results on TAs in 124 food and 611 feed samples were collected in two Member States. Most of the food and feed samples were left‐censored (below limit of detection/limit of quantification). A reliable exposure estimate was only possible for one food and one age class (toddlers). Based on the limited information, the CONTAM Panel concluded that the dietary exposure of toddlers could be up to seven times the group ARfD and could exceed the group ARfD on approximately 11 to 18 % of consumption days. TA toxicosis in livestock and companion animals is relatively rare.

Members of the genus Atropa contain various tropane alkaloids, including atropine ((±)-hyoscyamine) and scopolamine, which possess medicinal properties. Preserving the diverse genetic background of wild populations via optimal plant production from seeds could be essential for avoiding the loss of potential uses. We analyzed the germination ecology of two Atropa species comprising the threatened A. baetica and widespread A. belladonna to determine the: (1) influence of temperature, light, and seed age on germination patterns; (2) effects of cold stratification and gibberellic acid (GA3); (3) phenology of seedling emergence in outdoor conditions; (4) phenology of dormancy break and loss of viability in buried seeds; and (5) ability to form persistent soil seed banks. Freshly matured seeds exhibited conditional physiological dormancy, with germination at high temperatures (32/18 °C) but not at low and cold ones (5, 15/4, 20/7 °C). The germination ability increased with time of dry storage and with GA3, thereby suggesting nondeep physiological dormancy. Under outdoor conditions, no seedlings emerged during the first post-sown autumn, but emergence peaks occurred in late winter–early spring. Both species could form small persistent soil seed banks with short durations (3–5 years). A plant production protocol from seeds was established for both taxa.

Tropane alkaloids (TA) are valuable secondary plant metabolites which are mostly found in high concentrations in the Solanaceae and Erythroxylaceae families. The TAs, which are characterized by their unique bicyclic tropane ring system, can be divided into three major groups: hyoscyamine and scopolamine, cocaine and calystegines. Although all TAs have the same basic structure, they differ immensely in their biological, chemical and pharmacological properties. Scopolamine, also known as hyoscine, has the largest legitimate market as a pharmacological agent due to its treatment of nausea, vomiting, motion sickness, as well as smooth muscle spasms while cocaine is the 2nd most frequently consumed illicit drug globally. This review provides a comprehensive overview of TAs, highlighting their structural diversity, use in pharmaceutical therapy from both historical and modern perspectives, natural biosynthesis in planta and emerging production possibilities using tissue culture and microbial biosynthesis of these compounds.