Comparative transcriptome analysis to identify putative genes involved in thymol biosynthesis pathway in medicinal plant Trachyspermum ammi L

A comprehensive review on genomic resources in medicinally and industrially important major spices for future breeding programs: Status, utility and challenges

In the global market, spices possess a high-value but low-volume commodities of commerce. The food industry depends largely on spices for taste, flavor, and therapeutic properties in replacement of cheap synthetic ones. The estimated growth rate for spices demand in the world is ∼3.19%. Since spices grow in limited geographical regions, India is one of the leading producer of spices, contributing 25-30 percent of total world trade. Hitherto, there has been no comprehensive review of the genomic resources of industrially important major medicinal spices to overcome major impediments in varietal improvement and management. This review focuses on currently available genomic resources of 24 commercially significant spices, namely, Ajwain, Allspice, Asafoetida, Black pepper, Cardamom large, Cardamom small, Celery, Chillies, Cinnamon, Clove, Coriander, Cumin, Curry leaf, Dill seed, Fennel, Fenugreek, Garlic, Ginger, Mint, Nutmeg, Saffron, Tamarind, Turmeric and Vanilla. The advent of low-cost sequencing machines has contributed immensely to the voluminous data generation of these spices, cracking the complex genomic architecture, marker discovery, and understanding comparative and functional genomics. This review of spice genomics resources concludes the perspective and way forward to provide footprints by uncovering genome assemblies, sequencing and re-sequencing projects, transcriptome-based studies, non-coding RNA-mediated regulation, organelles-based resources, developed molecular markers, web resources, databases and AI-directed resources in candidate spices for enhanced breeding potential in them. Further, their integration with molecular breeding could be of immense use in formulating a strategy to protect and expand the production of the spices due to increased global demand.

Comparative transcriptome analysis to identify putative genes involved in carvacrol biosynthesis pathway in two species of Satureja, endemic medicinal herbs of Iran

Satureja is rich in phenolic monoterpenoids, mainly carvacrol, that is of interest due to diverse biological activities including antifungal and antibacterial. However, limited information is available regarding the molecular mechanisms underlying carvacrol biosynthesis and its regulation for this wonderful medicinal herb. To identify the putative genes involved in carvacrol and other monoterpene biosynthesis pathway, we generated a reference transcriptome in two endemic Satureja species of Iran, containing different yields (Satureja khuzistanica and Satureja rechingeri). Cross-species differential expression analysis was conducted between two species of Satureja. 210 and 186 transcripts related to terpenoid backbone biosynthesis were identified for S. khuzistanica and S. rechingeri, respectively. 29 differentially expressed genes (DEGs) involved in terpenoid biosynthesis were identified, and these DEGs were significantly enriched in monoterpenoid biosynthesis, diterpenoid biosynthesis, sesquiterpenoid and triterpenoid biosynthesis, carotenoid biosynthesis and ubiquinone and other terpenoid-quinone biosynthesis pathways. Expression patterns of S. khuzistanica and S. rechingeri transcripts involved in the terpenoid biosynthetic pathway were evaluated. In addition, we identified 19 differentially expressed transcription factors (such as MYC4, bHLH, and ARF18) that may control terpenoid biosynthesis. We confirmed the altered expression levels of DEGs that encode carvacrol biosynthetic enzymes using quantitative real-time PCR (qRT-PCR). This study is the first report on de novo assembly and transcriptome data analysis in Satureja which could be useful for an understanding of the main constituents of Satureja essential oil and future research in this genus.

The Current Developments in Medicinal Plant Genomics Enabled the Diversification of Secondary Metabolites' Biosynthesis

Medicinal plants produce important substrates for their adaptation and defenses against environmental factors and, at the same time, are used for traditional medicine and industrial additives. Plants have relatively little in the way of secondary metabolites via biosynthesis. Recently, the whole-genome sequencing of medicinal plants and the identification of secondary metabolite production were revolutionized by the rapid development and cheap cost of sequencing technology. Advances in functional genomics, such as transcriptomics, proteomics, and metabolomics, pave the way for discoveries in secondary metabolites and related key genes. The multi-omics approaches can offer tremendous insight into the variety, distribution, and development of biosynthetic gene clusters (BGCs). Although many reviews have reported on the plant and medicinal plant genome, chemistry, and pharmacology, there is no review giving a comprehensive report about the medicinal plant genome and multi-omics approaches to study the biosynthesis pathway of secondary metabolites. Here, we introduce the medicinal plant genome and the application of multi-omics tools for identifying genes related to the biosynthesis pathway of secondary metabolites. Moreover, we explore comparative genomics and polyploidy for gene family analysis in medicinal plants. This study promotes medicinal plant genomics, which contributes to the biosynthesis and screening of plant substrates and plant-based drugs and prompts the research efficiency of traditional medicine.

Transcriptomic analysis reveals the significant effects of fertilization on the biosynthesis of sesquiterpenes in Phoebe bournei

Phoebe bournei is a potential medicinal plant. Its essential oils (Eos) are mainly composed of sesquiterpenes that has potential activities of anti-bacteria and anti-tumors. In this study, we evaluated the effects of compost and compound fertilizer on the total amount and main components of Eos in P. bournei, we also studied the molecular mechanism undergoing this process by deep sequencing the genes involved in the biosynthesis of sesquiterpenes. Fertilization enhanced the total amount of main components in Eos from both leaves and twigs. Bicyclogermacrene, the primary sesquiterpene in the leaf EO, was significantly increased under compost treatment, while bicyclogermacrene and δ-cadinene (the second most abundant sesquiterpene) were decreased under compound fertilizer treatment. The two fertilizers had no significant effect on the abundance of the primary (+) - δ-cadinene in the twig EO, but had a positive effect on the second most abundant sesquiterpene copaene. Significant differences were observed in the number of differentially expressed genes (DEGs) with the leaves showing greater number of DEGs as compared to the twigs after compost treatment. Terpenoid backbone biosynthesis (TBB) is a key pathway of sesquiterpenes synthesis. The expression of genes regulating several important enzymes in TBB was altered after fertilization. After the compost treatment, the expression of the leaf DXS gene (ACQ66107.1), being closely related to the sesquiterpene biosynthesis in P. bournei leaves, was decreased. Compost and compound fertilizer altered the expression of the two important branch-point enzymes (FPPS and GGPPS) genes (ART33314.1 and ATT59265.1), which contributed to the changes of the total amount and components of P. bournei sesquiterpenes. This study provides a new insight into the future use of P. bournei for Eos.

Exploration of plant transcriptomes reveals five putative novel poleroviruses and an enamovirus

Transcriptome datasets available in public domain serve as valuable resource for identification and characterization of novel viral genomes. Poleroviruses are economically important plant-infecting RNA viruses belonging to the family Solemoviridae. In the present study, we explored the plant transcriptomes available in public domain and identified five putative novel poleroviruses tentatively named as Foeniculum vulgare polerovirus (FvPV), Kalanchoe marnieriana polerovirus (KmPV), Paspalum notatum polerovirus (PnPV), Piper methysticum polerovirus (PmPV), Trachyspermum ammi polerovirus (TaPV) and a novel enamovirus named as Celmisia lyallii enamovirus (ClEV) in Foeniculum vulgare, Kalanchoe marnieriana, Paspalum notatum, Piper methysticum, Trachyspermum ammi and Celmisia lyallii, respectively. Coding-complete genomes (5.56-5.74 kb) of CIEV, KmPV, PnPV, PmPV and TaPV were recovered while only the partial genome of FvPV could be recovered. The genome organization of identified viruses except ClEV is 5'-ORF0-ORF1-ORF2-ORF3a-ORF3-ORF4-ORF5-3' while that of ClEV is 5'-ORF0-ORF1-ORF2-ORF3-ORF5-3'. Phylogenetic analysis revealed that poleroviruses of apiaceous plants formed a monophyletic clade within the genus Polerovirus.

Application of High-Throughput Sequencing on the Chinese Herbal Medicine for the Data-Mining of the Bioactive Compounds

The Chinese Herbal Medicine (CHM) has been used worldwide in clinic to treat the vast majority of human diseases, and the healing effect is remarkable. However, the functional components and the corresponding pharmacological mechanism of the herbs are unclear. As one of the main means, the high-throughput sequencing (HTS) technologies have been employed to discover and parse the active ingredients of CHM. Moreover, a tremendous amount of effort is made to uncover the pharmacodynamic genes associated with the synthesis of active substances. Here, based on the genome-assembly and the downstream bioinformatics analysis, we present a comprehensive summary of the application of HTS on CHM for the synthesis pathways of active ingredients from two aspects: active ingredient properties and disease classification, which are important for pharmacological, herb molecular breeding, and synthetic biology studies.

Emerging roles of NAC transcription factor in medicinal plants: progress and prospects

Transcriptional factors act as mediators in regulating stress response in plants from signal perception to processing the directed gene expression. WRKY, MYB, AP2/ERF, etc. are some of the major families of transcription factors known to mediate stress mechanisms in plants by regulating the production of secondary metabolites. NAC domain-containing proteins are among these large transcription factors families in plants. These proteins play impulsive roles in plant growth, development, and various abiotic as well as biotic stresses. They are involved in regulating the different signaling pathways of plant hormones that direct a plant's immunity against pathogens, thereby affecting their immune responses. However, their role in stress regulation or defence mechanism in plants through the secondary metabolite biosynthesis pathway is studied for very few cases. Emerging concern over the requirement of medicinal plants for the production of biocompatible drugs and antibiotics, the study of these vast, affecting proteins should be focused to improve their qualitative and quantitative production further. In medicinal plants, phytochemicals and secondary metabolites are the major biochemicals that impose antimicrobial and other medicinal properties in these plants. This review compiles the NAC transcription factors reported in selected medicinal plants and their possible roles in different mechanisms. Further, the comprehensive understanding of the molecular mechanism, genetic engineering, and regulation responses of NAC TFs in medicinal plants, can lead to improvement in stress response, immunity, and production of usable secondary metabolites.

Impact of Genomic and Transcriptomic Resources on Apiaceae Crop Breeding Strategies

The Apiaceae taxon is one of the most important families of flowering plants and includes thousands of species used for food, flavoring, fragrance, medical and industrial purposes. This study had the specific intent of reviewing the main genomics and transcriptomic data available for this family and their use for the constitution of new varieties. This was achieved starting from the description of the main reproductive systems and barriers, with particular reference to cytoplasmic (CMS) and nuclear (NMS) male sterility. We found that CMS and NMS systems have been discovered and successfully exploited for the development of varieties only in Foeniculum vulgare, Daucus carota, Apium graveolens and Pastinaca sativa; whereas, strategies to limit self-pollination have been poorly considered. Since the constitution of new varieties benefits from the synergistic use of marker-assisted breeding in combination with conventional breeding schemes, we also analyzed and discussed the available SNP and SSR marker datasets (20 species) and genomes (8 species). Furthermore, the RNA-seq studies aimed at elucidating key pathways in stress tolerance or biosynthesis of the metabolites of interest were limited and proportional to the economic weight of each species. Finally, by aligning 53 plastid genomes from as many species as possible, we demonstrated the precision offered by the super barcoding approach to reconstruct the phylogenetic relationships of Apiaceae species. Overall, despite the impressive size of this family, we documented an evident lack of molecular data, especially because genomic and transcriptomic resources are circumscribed to a small number of species. We believe that our contribution can help future studies aimed at developing molecular tools for boosting breeding programs in crop plants of the Apiaceae family.

Illuminating the Plant Rhabdovirus Landscape through Metatranscriptomics Data

Rhabdoviruses infect a large number of plant species and cause significant crop diseases. They have a negative-sense, single-stranded unsegmented or bisegmented RNA genome. The number of plant-associated rhabdovirid sequences has grown in the last few years in concert with the extensive use of high-throughput sequencing platforms. Here, we report the discovery of 27 novel rhabdovirus genomes associated with 25 different host plant species and one insect, which were hidden in public databases. These viral sequences were identified through homology searches in more than 3000 plant and insect transcriptomes from the National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA) using known plant rhabdovirus sequences as the query. The identification, assembly and curation of raw SRA reads resulted in sixteen viral genome sequences with full-length coding regions and ten partial genomes. Highlights of the obtained sequences include viruses with unique and novel genome organizations among known plant rhabdoviruses. Phylogenetic analysis showed that thirteen of the novel viruses were related to cytorhabdoviruses, one to alphanucleorhabdoviruses, five to betanucleorhabdoviruses, one to dichorhaviruses and seven to varicosaviruses. These findings resulted in the most complete phylogeny of plant rhabdoviruses to date and shed new light on the phylogenetic relationships and evolutionary landscape of this group of plant viruses. Furthermore, this study provided additional evidence for the complexity and diversity of plant rhabdovirus genomes and demonstrated that analyzing SRA public data provides an invaluable tool to accelerate virus discovery, gain evolutionary insights and refine virus taxonomy.

Trachyspermum ammi and Cinnamomum verum as nutraceuticals: Spices rich in therapeutically significant protein tyrosine phosphatases

Nutraceuticals need special attention as preventive molecules to create a natural barrier against various dreadful diseases like cancer and to regulate metabolism. In the present study, two spices, Trachyspermum ammi and Cinnamomum verum, been identified as excellent Protein Tyrosine Phosphatases (PTPases) sources that play significant role in the regulation of cell signal transduction and developmental processes in plants as well as animals, being lucrative and potential targets for pharmacological modulation. PTPases from both cases were partially purified into 0%-40% and 40%-80% fractions based on ammonium sulfate saturation levels. Fraction (40%-80%) exhibited a purification level of 4.44-fold and 2.86-fold with specific activity of 44.06 and 23.33 U/mg for PTPases from T. ammi and C. verum, respectively. PTPases being found to be thermally stable up to 70°C imply their industrial significance. Kinetic studies showed K_m values to be 7.14 and 8.33 mM, whereas the activation energy (E_a ) values were 25.89 and 29.13 kJ/mol, respectively. Divalent cations: Cu²⁺ , Zn²⁺ , and Mn²⁺ acted as inhibitors of PTPases, from both sources. The K_i values of inhibitors varied from 0.014-0.125 mM in the descending order Cu²⁺  > Zn²⁺  > Mn²⁺ and Mn²⁺  > Cu²⁺  > Zn²⁺ for PTPases from T. ammi and C. verum, respectively. The inhibitory effect of sodium metavanadate aligns with prominent PTPase characteristics. In addition to these properties, the thermostability of PTPases from two spices enhances their significance in industries with therapeutically vital products. Although the source of PTPases is culinary spices, further studies are required to establish the utilization of PTPases as nutraceuticals and in therapeutic formulations. PRACTICAL APPLICATIONS: For a healthy lifestyle, awareness needs to be created by humankind towards food habits to minimize illnesses. Numerous studies have explored the consumption of nutraceutical products acts as a natural barrier and immune booster for various human ailments including SARS-COV-2. PTPases play important roles in regulating intracellular signaling and, ultimately, biological function along with their structural features. The importance of PTPases and their inhibitors has been implicated in various diseases like cancer, diabetes, and obesity. Further investigations need to be undertaken to explore the therapeutic properties of PTPases in both in vivo and in vitro for their clinical significance.

Comparative transcriptome analysis of roots, stems, and leaves of Pueraria lobata (Willd.) Ohwi: identification of genes involved in isoflavonoid biosynthesis

BACKGROUND

Pueraria lobata (Willd.) Ohwi is a valuable herb used in traditional Chinese medicine. Isoflavonoids are the major bioactive compounds in P. lobata, namely puerarin, daidzin, glycitin, genistin, daidzein, and glycitein, which have pharmacological properties of anti-cardiovascular, anti-hypertension, anti-inflammatory, and anti-arrhythmic.

METHODS

To characterize the corresponding genes of the compounds in the isoflavonoid pathway, RNA sequencing (RNA-Seq) analyses of roots, stems, and leaves of P. lobata were carried out on the BGISEQ-500 sequencing platform.

RESULTS

We identified 140,905 unigenes in total, of which 109,687 were annotated in public databases, after assembling the transcripts from all three tissues. Multiple genes encoding key enzymes, such as IF7GT and transcription factors, associated with isoflavonoid biosynthesis were identified and then further analyzed. Quantitative real-time PCR (qRT-PCR) results of some genes encoding key enzymes were consistent with our RNA-Seq analysis. Differentially expressed genes (DEGs) were determined by analyzing the expression profiles of roots compared with other tissues (leaves and stems). This analysis revealed numerous DEGs that were either uniquely expressed or up-regulated in the roots. Finally, quantitative analyses of isoflavonoid metabolites occurring in the three P. lobata tissue types were done via high-performance liquid-chromatography and tandem mass spectrometry methodology (HPLC-MS/MS). Our comprehensive transcriptome investigation substantially expands the genomic resources of P. lobata and provides valuable knowledge on both gene expression regulation and promising candidate genes that are involved in plant isoflavonoid pathways.

Transcriptional response of Asarum heterotropoides Fr. Schmidt var. mandshuricum (Maxim.) Kitag. leaves grown under full and partial daylight conditions

BACKGROUND

Asarum heterotropides Fr. Schmidt var. mandshuricum (Maxim.) Kitag. is an important medicinal and industrial plant, which is used in the treatment of various diseases. The main bioactive ingredient is the volatile oil having more than 82 identified components of which methyleugenol, safrole, myristicin, and toluene account for about 70% of the total volume. As a sciophyte plant, the amount of light it absorbs through leaves is an important factor for growth and metabolism.

RESULTS

We grew Asarum plants under full, 50, 28, and 12% sunlight conditions to investigate the effect of different light irradiances on the four major volatile oil components. We employed de novo transcriptome sequencing to understand the transcriptional behavior of Asarum leaves regarding the biosynthetic pathways of the four volatile oil components, photosynthesis and biomass accumulation, and hormone signaling. Our results demonstrated that the increasing light conditions promoted higher percent of the four components. Under full sunlight conditions, cinnamyl alcohol dehydrogenase and cytochrome p450719As were upregulated and led the increased methyleugenol, safrole, and myristicin. The transcriptomic data also showed that Asarum leaves, under full sunlight conditions, adjust their photosynthesis-antenna proteins as a photoprotective response with the help of carotenoids. Plant hormone-signaling related genes were also differentially expressed between full sunlight and low light conditions.

CONCLUSIONS

High light induces accumulation of major bioactive ingredients A. heterotropides volatile oil and this is ascribed to upregulation of key genes such as cinnamyl alcohol dehydrogenase and cytochrome p450719As. The transcriptome data presented here lays the foundation of further understanding of light responses in sciophytes and provides guidance for increasing bioactive molecules in Asarum.

De novo assembly and characterization of transcriptome in the medicinal plant Euphorbia jolkini

BACKGROUND

Euphorbia jolkini, a medicinal herb that grows on the warm beaches in Japan and South Korea, is known to be used for traditional medicines to treat a variety of ailments, including bruises, stiffness, indigestion, toothache, and diabetes.

OBJECTIVE

It is to analyze the whole transcriptome and identify the genes related to the phenylpropanoid biosynthesis in the medicinally important herb E jolkini.

METHODS

Paired-end Illumina HiSeq™ 2500 sequencing technology was employed for cDNA library construction and Illumina sequencing. Public databases like TAIR (The Arabidopsis Information Resource), Swissprot and KEGG (Kyoto Encyclopedia of Genes and Genomes) were used for annotations of unigenes obtained.

RESULTS

The transcriptome of E. jolkini generated 139,215 assembled transcripts with an average length of 868 bp and an N50 value of 1460 bp that were further clustered using CD-HIT into 93,801 unigenes with an average length of 847 bp (N50-1410 bp). Sixty-three percent of the coding sequences (CDS) were annotated from the longest open reading frame (ORF). A remarkable percentage of unigenes were annotated against various databases. The differentially expressed gene analysis revealed that the expression of genes related to the terpenoid backbone biosynthesis pathway was higher in the flowers, whereas that of genes related to the phenylpropanoid biosynthesis pathway was both up- and downregulated in flowers and leaves. A search of against the transcription factor domain found 1023 transcription factors (TFs) that were from 54 TF families.

CONCLUSION

Assembled sequences of the E. jolkini transcriptome are made available for the first time in this study E. jolkini and lay a foundation for the investigation of secondary metabolite biosynthesis.

Striking essential oil: tapping into a largely unexplored source for drug discovery

Essential oils (EOs) have been used therapeutically for centuries. In recent decades, randomized controlled (clinical) trials have supported efficacy in specific therapeutic indications for a few of them. Some EOs, their components or derivatives thereof have been approved as drugs. Nevertheless, they are still considered products that are mainly used in complementary and alternative medicine. EO components occupy a special niche in chemical space, that offers unique opportunities based on their unusual physicochemical properties, because they are typically volatile and hydrophobic. Here we evaluate selected physicochemical parameters, used in conventional drug discovery, of EO components present in a range of commercially available EOs. We show that, contrary to generally held belief, most EO components meet current-day requirements of medicinal chemistry for good drug candidates. Moreover, they also offer attractive opportunities for lead optimization or even fragment-based drug discovery. Because their therapeutic potential is still under-scrutinized, we propose that this be explored more vigorously with present-day methods.

Application of genetics and biotechnology for improving medicinal plants

Plant tissue culture has been used for conservation, micropropagation, and in planta overproduction of some pharma molecules of medicinal plants. New biotechnology-based breeding methods such as targeted genome editing methods are able to create custom-designed medicinal plants with different secondary metabolite profiles. For a long time, humans have used medicinal plants for therapeutic purposes and in food and other industries. Classical biotechnology techniques have been exploited in breeding medicinal plants. Now, it is time to apply faster biotechnology-based breeding methods (BBBMs) to these valuable plants. Assessment of the genetic diversity, conservation, proliferation, and overproduction are the main ways by which genetics and biotechnology can help to improve medicinal plants faster. Plant tissue culture (PTC) plays an important role as a platform to apply other BBBMs in medicinal plants. Agrobacterium-mediated gene transformation and artificial polyploidy induction are the main BBBMs that are directly dependent on PTC. Manageable regulation of endogens and/or transferred genes via engineered zinc-finger proteins or transcription activator-like effectors can help targeted manipulation of secondary metabolite pathways in medicinal plants. The next-generation sequencing techniques have great potential to study the genetic diversity of medicinal plants through restriction-site-associated DNA sequencing (RAD-seq) technique and also to identify the genes and enzymes that are involved in the biosynthetic pathway of secondary metabolites through precise transcriptome profiling (RNA-seq). The sequence-specific nucleases of transcription activator-like effector nucleases (TALENs), zinc-finger nucleases, and clustered regularly interspaced short palindromic repeats-associated (Cas) are the genome editing methods that can produce user-designed medicinal plants. These current targeted genome editing methods are able to manage plant synthetic biology and open new gates to medicinal plants to be introduced into appropriate industries.