Discovery and characterization of two highly divergent variants of a novel potyvirus species infecting Madagascar periwinkle (Catharanthus roseus L.)

During summer 2022, a cluster of Madagascar periwinkle plants with white and mauve flowers were observed with foliar mild yellow mosaic symptoms on a private property in Harlingen, Cameron County, Texas. The symptoms were reproduced on mechanically inoculated periwinkle and Nicotiana benthamiana plants. Virions of 776 to 849 nm in length and 11.7 to 14.8 nm in width were observed in transmission electron microscopy of leaf dip preparations made from symptomatic periwinkle leaves. Highthroughput sequencing (HTS) analysis of total RNA extracts from symptomatic leaves revealed the occurrence of two highly divergent variants of a novel Potyvirus species as the only virus-like sequences present in the sample. The complete genomes of both variants were independently amplified via RT-PCR, cloned, and Sanger sequenced. The 5' and 3' of the genomes were acquired using RACE methodology. The assembled virus genomes were 9,936 and 9,944 nucleotides (nt) long and they shared 99.9-100% identities with the respective HTS-derived genomes. Each genome encoded hypothetical polyprotein of 3,171 amino acids (aa) (362.6 kDa) and 3,173 aa (362.7 kDa), respectively, and they shared 77.3%/84.4% nt/aa polyproteins identities, indicating that they represent highly divergent variants of the same Potyvirus species. Both genomes also shared below species threshold polyprotein identity levels with the most closely phylogenetically related known potyviruses thus indicating that they belong to a novel species. The name periwinkle mild yellow mosaic virus (PwMYMV) is given to the potyvirus with complete genomes of 9,936 nt for variant 1 (PwMYMV-1) and 9,944 nt for variant 2 (PwMYMV-2). We propose that PwMYMV be assigned into the genus Potyvirus (family Potyviridae).

[A Systematic Review of the Pharmacological and Phytochemical Profiles of Madagascar periwinkle as Potential Dietary Supplement]

Madagascar periwinkle (Catharanthus roseus) is a plant species known for its rich pharmacological and phytochemical properties. This systematic review aims to comprehensively evaluate the potential of Madagascar periwinkle as a dietary supplement. A thorough search of relevant databases yielded studies focusing on the pharmacological activities and phytochemical constituents of Madagascar periwinkle. The review highlights the diverse pharmacological effects of Madagascar periwinkle, including anti-cancer, anti-diabetic, anti-inflammatory, and antimicrobial properties, among others. Furthermore, the phytochemical analysis revealed the presence of various bioactive compounds such as alkaloids, flavonoids, terpenoids, and phenolics, which contribute to its medicinal properties. Despite the promising findings, further research is warranted to elucidate the mechanisms of action, safety profile, and potential interactions of Madagascar periwinkle as a dietary supplement. Overall, this systematic review provides valuable insights into the pharmacological and phytochemical profiles of Madagascar periwinkle, suggesting its potential as a natural dietary supplement with diverse health benefits.

Fungal Elicitation Enhances Vincristine and Vinblastine Yield in the Embryogenic Tissues of Catharanthus roseus

Fungal elicitation could improve the secondary metabolite contents of in vitro cultures. Herein, we report the effect of Fusarium oxysporum on vinblastine and vincristine alkaloid yields in Catharanthus roseus embryos. The study revealed increased yields of vinblastine and vincristine in Catharanthus tissues. Different concentrations, i.e., 0.05% (T1), 0.15% (T2), 0.25% (T3), and 0.35% (T4), of an F. oxysporum extract were applied to a solid MS medium in addition to a control (T0). Embryogenic calli were formed from the hypocotyl explants of germinating seedlings, and the tissues were exposed to Fusarium extract elicitation. The administration of the F. oxysporum extract improved the growth of the callus biomass, which later differentiated into embryos, and the maximum induction of somatic embryos was noted T2 concentration (102.69/callus mass). A biochemical analysis revealed extra accumulations of sugar, protein, and proline in the fungus-elicitated cultivating tissues. The somatic embryos germinated into plantlets on full-strength MS medium supplemented with 2.24 µM of BA. The germination rate of the embryos and the shoot and root lengths of the embryos were high at low doses of the Fusarium treatment. The yields of vinblastine and vincristine were measured in different treated tissues via high-pressure thin-layer chromatography (HPTLC). The yield of vinblastine was high in mature (45-day old) embryos (1.229 µg g-1 dry weight), which were further enriched (1.267 µg g-1 dry weight) via the F. oxysporum-elicitated treatment, especially at the T2 concentration. Compared to vinblastine, the vincristine content was low, with a maximum of 0.307 µg g-1 dry weight following the addition of the F. oxysporum treatment. The highest and increased yields of vinblastine and vincristine, 7.88 and 15.50%, were noted in F. oxysporum-amended tissues. The maturated and germinating somatic embryos had high levels of SOD activity, and upon the addition of the fungal extracts, the enzyme's activity was further elevated, indicating that the tissues experienced cellular stress which yielded increased levels of vinblastine and vincristine following the T2/T1 treatments. The improvement in the yields of these alkaloids could augment cancer healthcare treatments, making them easy, accessible, and inexpensive.

Iron (Fe) toxicity, uptake, translocation, and physio-morphological responses in Catharanthus roseus

Iron (Fe) toxicity in plant species depends on the availability of Fe in the soil, uptake ability by the root system, and translocation rate to other parts of the plant. The aim of this study was to assess Fe uptake by root tissues of Catharanthus roseus, translocation rate to leaf tissues, and the impairment of plant physio-morphological characteristics. Fe uptake by the roots (~ 700 µg g-1 DW) of C. roseus was observed during the early exposure period (1 week), and translocation factor from root to shoot was fluctuated as an independent strategy. A high level of Fe content in the root tissues significantly inhibited root length and root dry weight. Under acidic pH condition, an enrichment of Fe in the shoots (~ 400 µg g-1 DW) led to increase in leaf temperature (> 2.5 °C compared to control) and crop stress index (> 0.6), resulting in stomatal closure, subsequently decreasing CO2 assimilation rate and H2O transpiration rate. An increment of CSI in Fe-stressed plants was negatively related to stomatal conductance, indicating stomatal closure with an increase in Fe in the leaf tissues. High Fe levels in the leaf tissues directly induced toxic symptoms including leaf bronzing, leaf spotting, leaf necrosis, leaf chlorosis, and leaf senescence in C. roseus plants. In summary, C. roseus was identified as a good candidate plant for Fe phytoextraction, depending on Fe bioaccumulation, therefore 50 mM Fe treatment was designated as an excess Fe to cause the growth inhibition, especially in the prolonged Fe incubation periods.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01379-5.

Molecular and biochemical characterization of Catharanthus roseus perivine-Nβ-methyltransferase

The biosynthesis of monoterpenoid indole alkaloids in Catharanthus roseus has been most extensively studied, leading to the detailed characterization of the pathway for the formation of their well-known anticancer alkaloids. The present study describes the identification, molecular cloning, and functional expression of C. roseus perivine-N_β-methyltransferase (PeNMT) that converts perivine to N_β-methylperivine (vobasine). PeNMT is member of a recently discovered γ-tocopherol-like N-methyltransferase (γ-TLMT) gene family that displays high substrate specificity and that appears to have evolved in the Vinceae tribe of Apocynaceae family where most N-methylated MIAs have been identified in the phytochemical literature.

Site directed mutagenesis of Catharanthus roseus (+)-vincadifformine 19-hydroxylase (CYP71BY3) results in two distinct enzymatic functions

The most abundant monoterpenoid indole alkaloids (MIAs) in Catharanthus roseus roots include lochnericine and (+)-echitovenine. The formation of (+)-echitovenine involves a 3-step pathway including (+)-vincadifformine-19-hydroxylase (V19H) that differentiates it from a parallel pathway involved in the formation of lochnericine, hörhammericine and its O-acetylated derivative. Homology based modeling and docking experiments in the present study show that (+) and (-) vincadifformine can occupy the V19H active site and is proven experimentally by showing that (-)-vincadifformine is a competitive inhibitor of V19H. Comparative modeling of V19H with tabersonine 3-oxidase (T3O) and tabersonine 19-hydroxylase (T19H) that accept (-)-aspidosperma MIAs identified four conserved amino acid residues in T3O and T19H that were different in the V19H binding site and were used to generate a series of single-, double-, or four-point mutations in V19H. While all mutants retained their ability to convert (+)-vincadifformine to (+)-minovincinine only the four-point mutant gained T3O activity enabling it to convert (-)-tabersonine to tabersonine 2,3-epoxide. The gain of T3O-like activity following mutagenesis without the loss of V19H activity supports the hypothesis that V19H shares a common ancestor to T3O which is involved in vindoline biosynthesis in C. roseus leaves.

Generous Hosts: 'Candidatus Liberibacter asiaticus' Growth in Madagascar Periwinkle (Catharanthus roseus) Highlights Its Nutritional Needs

'Candidatus Liberibacter asiaticus', the putative causal agent of citrus greening, is not available in pure culture yet. In addition to trees of citrus and citrus relatives, 'Ca. L. asiaticus' can grow in Madagascar periwinkle (Catharanthus roseus). Using gas chromatography-mass spectrometry, we compared the phloem sap composition in sweet orange 'Valencia' (Citrus sinensis) and periwinkle plants after the infection with 'Ca. L. asiaticus'. Interestingly, in contrast to our previous studies of total leaf metabolites, we found that, compared with uninfected phloem sap, the organic acids implicated in the tricarboxylic acid cycle (TCA) cycle including citrate, isocitrate, succinate, fumarate, and malate were reduced significantly in the infected phloem saps of both species. As a result of the reduction of organic acids content, the pH of infected phloem saps was increased. We hypothesize that the bacterial growth induces the mitochondrial TCA cycle in parenchyma cells to produce more of these compounds to be used as a bacterial carbon source. Once these compounds reach a low level in the phloem sap, the bacterium may send a signal, yet to be identified, to initiate a feedback loop to further induce the TCA cycle. Phloem blockage might be another reason behind the reduced translocation of TCA cycle intermediates within the phloem. The net result, localized availability of organic acids, likely benefits bacterial growth and may explain the unequal distribution of 'Ca. L. asiaticus' within infected trees. These findings may help in designing media for the pure culturing of 'Ca. L. asiaticus'.

A Rapid and Efficient Vacuum-Based Agroinfiltration Protocol for Transient Gene Overexpression in Leaves of Catharanthus roseus

Functional genomics analyses in planta can be hampered in non-model plants that are recalcitrant to the genetic transformation such as the medicinal plant Catharanthus roseus (Apocynaceae). No stable transformation and regeneration of plantlets have been achieved with a high efficiency in this plant to date. In addition, while virus-mediated transient gene silencing has been reported a decade ago in C. roseus, tools for transient overexpression remain scarce. Here, we describe an efficient and reliable methodology for transiently overexpressing any gene of interest in C. roseus leaves. This protocol combines a vacuum-based Agroinfiltration approach and the high translational efficiency of a deconstructed virus-based binary vector (pEAQ-HT). The described methodology is robust, easy to perform, and results in high amount of transient expression in C. roseus. This protocol is expected to serve as valuable tool to enhance the in planta characterization of gene functions or even transiently knock-in novel enzymatic activities.

Subfunctionalization of Paralog Transcription Factors Contributes to Regulation of Alkaloid Pathway Branch Choice in Catharanthus roseus

Catharanthus roseus produces a diverse range of specialized metabolites of the monoterpenoid indole alkaloid (MIA) class in a heavily branched pathway. Recent great progress in identification of MIA biosynthesis genes revealed that the different pathway branch genes are expressed in a highly cell type- and organ-specific and stress-dependent manner. This implies a complex control by specific transcription factors (TFs), only partly revealed today. We generated and mined a comprehensive compendium of publicly available C. roseus transcriptome data for MIA pathway branch-specific TFs. Functional analysis was performed through extensive comparative gene expression analysis and profiling of over 40 MIA metabolites in the C. roseus flower petal expression system. We identified additional members of the known BIS and ORCA regulators. Further detailed study of the ORCA TFs suggests subfunctionalization of ORCA paralogs in terms of target gene-specific regulation and synergistic activity with the central jasmonate response regulator MYC2. Moreover, we identified specific amino acid residues within the ORCA DNA-binding domains that contribute to the differential regulation of some MIA pathway branches. Our results advance our understanding of TF paralog specificity for which, despite the common occurrence of closely related paralogs in many species, comparative studies are scarce.

An engineered combinatorial module of transcription factors boosts production of monoterpenoid indole alkaloids in Catharanthus roseus

To fend off microbial pathogens and herbivores, plants have evolved a wide range of defense strategies such as physical barriers, or the production of anti-digestive proteins or bioactive specialized metabolites. Accumulation of the latter compounds is often regulated by transcriptional activation of the biosynthesis pathway genes by the phytohormone jasmonate-isoleucine. Here, we used our recently developed flower petal transformation method in the medicinal plant Catharanthus roseus to shed light on the complex regulatory mechanisms steering the jasmonate-modulated biosynthesis of monoterpenoid indole alkaloids (MIAs), to which the anti-cancer compounds vinblastine and vincristine belong. By combinatorial overexpression of the transcriptional activators BIS1, ORCA3 and MYC2a, we provide an unprecedented insight into the modular transcriptional control of MIA biosynthesis. Furthermore, we show that the expression of an engineered de-repressed MYC2a triggers a tremendous reprogramming of the MIA pathway, finally leading to massively increased accumulation of at least 23 MIAs. The current study unveils an innovative approach for future metabolic engineering efforts for the production of valuable bioactive plant compounds in non-model plants.

Expression of tabersonine 16-hydroxylase and 16-hydroxytabersonine-O-methyltransferase in Catharanthus roseus hairy roots

The monoterpene indole alkaloids vindoline and catharanthine, which are exclusively synthesized in the medicinal plant Catharanthus roseus, are the two important precursors for the production of pharmaceutically important anti-cancer medicines vinblastine and vincristine. Hairy root culture is an ideal platform for alkaloids production due to its industrial scalability, genetic and chemical stability, and availability of genetic engineering tools. However, C. roseus hairy roots do not produce vindoline due to the lack of expression of the seven-step pathway from tabersonine to vindoline [Murata & De Luca (2015) Plant Journal, 44, 581-594]. The present study describes the genetic engineering of the first two genes tabersonine 16-hydroxylase (T16H) and 16-O-methyl transferase (16OMT) in the missing vindoline pathway under the control of a glucocorticoid-inducible promoter to direct tabersonine toward vindoline biosynthesis in C. roseus hairy roots. In two transgenic hairy roots, the induced overexpression of T16H and 16OMT resulted in the accumulation of vindoline pathway metabolites 16-hydroxytabersonine and 16-methoxytabersonine. The levels of root-specific alkaloids, including lochnericine, 19-hydroxytabersonine and hörhammericine, significantly decreased in the induced hairy roots in comparison to the uninduced control lines. This suggests tabersonine was successfully channeled to the vindoline pathway away from the roots competing pathway based on the overexpression. Interestingly, another two new metabolites were detected in the induced hairy roots and proposed to be the epoxidized-16-hydroxytabersonine and lochnerinine. Thus, the introduction of vindoline pathway genes in hairy roots can cause unexpected terpenoid indole alkaloids (TIA) profile alterations. Furthermore, we observed complex transcriptional changes in TIA genes and regulators detected by RT-qPCR which highlight the tight regulation of the TIA pathway in response to T16H and 16OMT engineering in C. roseus hairy roots.

The basic helix-loop-helix transcription factor BIS2 is essential for monoterpenoid indole alkaloid production in the medicinal plant Catharanthus roseus

Monoterpenoid indole alkaloids (MIAs) are produced as plant defence compounds. In the medicinal plant Catharanthus roseus, they comprise the anticancer compounds vinblastine and vincristine. The iridoid (monoterpenoid) pathway forms one of the two branches that feed MIA biosynthesis and its activation is regulated by the transcription factor (TF) basic helix-loop-helix (bHLH) iridoid synthesis 1 (BIS1). Here, we describe the identification and characterisation of BIS2, a jasmonate (JA)-responsive bHLH TF expressed preferentially in internal phloem-associated parenchyma cells, which transactivates promoters of iridoid biosynthesis genes and can homodimerise or form heterodimers with BIS1. Stable overexpression of BIS2 in C. roseus suspension cells and transient ectopic expression of BIS2 in C. roseus petal limbs resulted in increased transcript accumulation of methylerythritol-4-phosphate and iridoid pathway genes, but not of other MIA genes or triterpenoid genes. Transcript profiling also indicated that BIS2 expression is part of an amplification loop, as it is induced by overexpression of either BIS1 or BIS2. Accordingly, silencing of BIS2 in C. roseus suspension cells completely abolished the JA-induced upregulation of the iridoid pathway genes and subsequent MIA accumulation, despite the presence of induced BIS1, indicating that BIS2 is essential for MIA production in C. roseus.

Engineering overexpression of ORCA3 and strictosidine glucosidase in Catharanthus roseus hairy roots increases alkaloid production

Catharanthus roseus produces many pharmaceutically important terpenoid indole alkaloids (TIAs) such as vinblastine, vincristine, ajmalicine, and serpentine. Past metabolic engineering efforts have pointed to the tight regulation of the TIA pathway and to multiple rate-limiting reactions. Transcriptional regulator ORCA3 (octadecanoid responsive Catharanthus AP2-domain protein), activated by jasmonic acid, plays a central role in regulating the TIA pathway. In this study, overexpressing ORCA3 under the control of a glucocorticoid-inducible promoter in C. roseus hairy roots resulted in no change in the total amount of TIAs measured. RT-qPCR results showed that ORCA3 overexpression triggered the upregulation of transcripts of most of the known TIA pathway genes. One notable exception was the decrease in strictosidine glucosidase (SGD) transcripts. These results corresponded to previously published results. In this study, ORCA3 and SGD were both engineered in hairy roots under the control of a glucocorticoid-inducible promoter. Co-overexpression of ORCA3 and SGD resulted in a significant (p < 0.05) increase in serpentine by 44 %, ajmalicine by 32 %, catharanthine by 38 %, tabersonine by 40 %, lochnericine by 60 % and hörhammericine by 56 % . The total alkaloid pool was increased significantly by 47 %. Thus, combining overexpression of a positive regulator and a pathway gene which is not controlled by this regulator provided a way to enhance alkaloid production.

Examining the transcriptional response of overexpressing anthranilate synthase in the hairy roots of an important medicinal plant Catharanthus roseus by RNA-seq

BACKGROUND

Clinically important anti-cancer drugs vinblastine and vincristine are solely synthesized by the terpenoid indole alkaloid (TIA) pathway in Catharanthus roseus. Anthranilate synthase (AS) is a rate-limiting enzyme in the TIA pathway. The transgenic C. roseus hairy root line overexpressing a feedback insensitive ASα subunit under the control of an inducible promoter and the ASβ subunit constitutively was previously created for the overproduction of TIAs. However, both increases and decreases in TIAs were detected after overexpressing ASα. Although genetic modification is targeted to one gene in the TIA pathway, it could trigger global transcriptional changes that can directly or indirectly affect TIA biosynthesis. In this study, Illumina sequencing and RT-qPCR were used to detect the transcriptional responses to overexpressing AS, which can increase understanding of the complex regulation of the TIA pathway and further inspire rational metabolic engineering for enhanced TIA production in C. roseus hairy roots.

RESULTS

Overexpressing AS in C. roseus hairy roots altered the transcription of most known TIA pathway genes and regulators after 12, 24, and 48 h induction detected by RT-qPCR. Changes in the transcriptome of C. roseus hairy roots was further investigated 18 hours after ASα induction and compared to the control hairy roots using RNA-seq. A unigene set of 30,281 was obtained by de novo assembly of the sequencing reads. Comparison of the differentially expressed transcriptional profiles resulted in 2853 differentially expressed transcripts. Functional annotation of these transcripts revealed a complex and systematically transcriptome change in ASαβ hairy roots. Pathway analysis shows alterations in many pathways such as aromatic amino acid biosynthesis, jasmonic acid (JA) biosynthesis and other secondary metabolic pathways after perturbing AS. Moreover, many genes in overall stress response were differentially expressed after overexpressing ASα.

CONCLUSION

The transcriptomic analysis illustrates overexpressing AS stimulates the overall stress response and affects the metabolic networks in C. roseus hairy roots. The up-regulation of endogenous JA biosynthesis pathway indicates the involvement of JA signal transduction to regulate TIA biosynthesis in ASαβ engineered roots and explained why many of the transcripts for TIA genes and regulators are seen to increase with AS overexpression.

The bHLH transcription factor BIS1 controls the iridoid branch of the monoterpenoid indole alkaloid pathway in Catharanthus roseus

Plants make specialized bioactive metabolites to defend themselves against attackers. The conserved control mechanisms are based on transcriptional activation of the respective plant species-specific biosynthetic pathways by the phytohormone jasmonate. Knowledge of the transcription factors involved, particularly in terpenoid biosynthesis, remains fragmentary. By transcriptome analysis and functional screens in the medicinal plant Catharanthus roseus (Madagascar periwinkle), the unique source of the monoterpenoid indole alkaloid (MIA)-type anticancer drugs vincristine and vinblastine, we identified a jasmonate-regulated basic helix-loop-helix (bHLH) transcription factor from clade IVa inducing the monoterpenoid branch of the MIA pathway. The bHLH iridoid synthesis 1 (BIS1) transcription factor transactivated the expression of all of the genes encoding the enzymes that catalyze the sequential conversion of the ubiquitous terpenoid precursor geranyl diphosphate to the iridoid loganic acid. BIS1 acted in a complementary manner to the previously characterized ethylene response factor Octadecanoid derivative-Responsive Catharanthus APETALA2-domain 3 (ORCA3) that transactivates the expression of several genes encoding the enzymes catalyzing the conversion of loganic acid to the downstream MIAs. In contrast to ORCA3, overexpression of BIS1 was sufficient to boost production of high-value iridoids and MIAs in C. roseus suspension cell cultures. Hence, BIS1 might be a metabolic engineering tool to produce sustainably high-value MIAs in C. roseus plants or cultures.

Phytochemical genomics of the Madagascar periwinkle: Unravelling the last twists of the alkaloid engine

The Madagascar periwinkle produces a large palette of Monoterpenoid Indole Alkaloids (MIAs), a class of complex alkaloids including some of the most valuable plant natural products with precious therapeutical values. Evolutionary pressure on one of the hotspots of biodiversity has obviously turned this endemic Malagasy plant into an innovative alkaloid engine. Catharanthus is a unique taxon producing vinblastine and vincristine, heterodimeric MIAs with complex stereochemistry, and also manufactures more than 100 different MIAs, some shared with the Apocynaceae, Loganiaceae and Rubiaceae members. For over 60 years, the quest for these powerful anticancer drugs has inspired biologists, chemists, and pharmacists to unravel the chemistry, biochemistry, therapeutic activity, cell and molecular biology of Catharanthus roseus. Recently, the "omics" technologies have fuelled rapid progress in deciphering the last secret of strictosidine biosynthesis, the central precursor opening biosynthetic routes to several thousand MIA compounds. Dedicated C. roseus transcriptome, proteome and metabolome databases, comprising organ-, tissue- and cell-specific libraries, and other phytogenomic resources, were developed for instance by PhytoMetaSyn, Medicinal Plant Genomic Resources and SmartCell consortium. Tissue specific library screening, orthology comparison in species with or without MIA-biochemical engines, clustering of gene expression profiles together with various functional validation strategies, largely contributed to enrich the toolbox for plant synthetic biology and metabolic engineering of MIA biosynthesis.

Iridoid Synthase Activity Is Common among the Plant Progesterone 5β-Reductase Family

Catharanthus roseus, the Madagascar periwinkle, synthesizes bioactive monoterpenoid indole alkaloids, among which the anti-cancer drugs vinblastine and vincristine. The monoterpenoid branch of the alkaloid pathway leads to the secoiridoid secologanin and involves the enzyme iridoid synthase (IS), a member of the progesterone 5β-reductase (P5βR) family. IS reduces 8-oxogeranial to iridodial. Through transcriptome mining, we show that IS belongs to a family of six C. roseus P5βR genes. Characterisation of recombinant CrP5βR proteins demonstrates that all but CrP5βR3 can reduce progesterone, and thus can be classified as P5βRs. Three of them, namely CrP5βR1, CrP5βR2 and CrP5βR4, could also reduce 8-oxogeranial, pointing to a possible redundancy with IS (corresponding to CrP5βR5) in secoiridoid synthesis. In depth functional analysis by subcellular protein localisation, gene expression analysis, in situ hybridisation and virus-induced gene silencing, indicates that besides IS, CrP5βR4 may also participate in secoiridoid biosynthesis. Finally, we cloned a set of P5βR genes from angiosperm plant species not known to produce iridoids and demonstrate that the corresponding recombinant proteins are also capable of using 8-oxogeranial as a substrate. This suggests that 'IS activity' is intrinsic to angiosperm P5βR proteins and has evolved early during evolution.

Vinca alkaloids

Vinca alkaloids are a subset of drugs obtained from the Madagascar periwinkle plant. They are naturally extracted from the pink periwinkle plant, Catharanthus roseus G. Don and have a hypoglycemic as well as cytotoxic effects. They have been used to treat diabetes, high blood pressure and have been used as disinfectants. The vinca alkaloids are also important for being cancer fighters. There are four major vinca alkaloids in clinical use: Vinblastine (VBL), vinorelbine (VRL), vincristine (VCR) and vindesine (VDS). VCR, VBL and VRL have been approved for use in the United States. Vinflunine is also a new synthetic vinca alkaloid, which has been approved in Europe for the treatment of second-line transitional cell carcinoma of the urothelium is being developed for other malignancies. Vinca alkaloids are the second-most-used class of cancer drugs and will stay among the original cancer therapies. Different researches and studies for new vinca alkaloid applications will be carried out in this regard.

CathaCyc, a metabolic pathway database built from Catharanthus roseus RNA-Seq data

The medicinal plant Madagascar periwinkle (Catharanthus roseus) synthesizes numerous terpenoid indole alkaloids (TIAs), such as the anticancer drugs vinblastine and vincristine. The TIA pathway operates in a complex metabolic network that steers plant growth and survival. Pathway databases and metabolic networks reconstructed from 'omics' sequence data can help to discover missing enzymes, study metabolic pathway evolution and, ultimately, engineer metabolic pathways. To date, such databases have mainly been built for model plant species with sequenced genomes. Although genome sequence data are not available for most medicinal plant species, next-generation sequencing is now extensively employed to create comprehensive medicinal plant transcriptome sequence resources. Here we report on the construction of CathaCyc, a detailed metabolic pathway database, from C. roseus RNA-Seq data sets. CathaCyc (version 1.0) contains 390 pathways with 1,347 assigned enzymes and spans primary and secondary metabolism. Curation of the pathways linked with the synthesis of TIAs and triterpenoids, their primary metabolic precursors, and their elicitors, the jasmonate hormones, demonstrated that RNA-Seq resources are suitable for the construction of pathway databases. CathaCyc is accessible online (http://www.cathacyc.org) and offers a range of tools for the visualization and analysis of metabolic networks and 'omics' data. Overlay with expression data from publicly available RNA-Seq resources demonstrated that two well-characterized C. roseus terpenoid pathways, those of TIAs and triterpenoids, are subject to distinct regulation by both developmental and environmental cues. We anticipate that databases such as CathaCyc will become key to the study and exploitation of the metabolism of medicinal plants.