Development of a Cell Suspension Culture System for Promoting Alkaloid and Vinca Alkaloid Biosynthesis Using Endophytic Fungi Isolated from Local Catharanthus roseus

Microbial allies: exploring fungal endophytes for biosynthesis of terpenoid indole alkaloids

Terpenoid indole alkaloids (TIAs) are natural compounds found in medicinal plants that exhibit various therapeutic activities, such as antimicrobial, anti-inflammatory, antioxidant, anti-diabetic, anti-helminthic, and anti-tumor properties. However, the production of these alkaloids in plants is limited, and there is a high demand for them due to the increasing incidence of cancer cases. To address this research gap, researchers have focused on optimizing culture media, eliciting metabolic pathways, overexpressing genes, and searching for potential sources of TIAs in organisms other than plants. The insufficient number of essential genes and enzymes in the biosynthesis pathway is the reason behind the limited production of TIAs. As the field of natural product discovery from biological species continues to grow, endophytes are being investigated more and more as potential sources of bioactive metabolites with a variety of chemical structures. Endophytes are microorganisms (fungi, bacteria, archaea, and actinomycetes), that exert a significant influence on the metabolic pathways of both the host plants and the endophytic cells. Bio-prospection of fungal endophytes has shown the discovery of novel, high-value bioactive compounds of commercial significance. The discovery of therapeutically significant secondary metabolites has been made easier by endophytic entities' abundant but understudied diversity. It has been observed that fungal endophytes have better intermediate processing ability due to cellular compartmentation. This paper focuses on fungal endophytes and their metabolic ability to produce complex TIAs, recent advancements in this area, and addressing the limitations and future perspectives related to TIA production.

Genome Characteristics of the Endophytic Fungus Talaromyces sp. DC2 Isolated from Catharanthus roseus (L.) G. Don

Talaromyces sp. DC2 is an endophytic fungus that was isolated from the stem of Catharanthus roseus (L.) G. Don in Hanoi, Vietnam and is capable of producing vinca alkaloids. This study utilizes the PacBio Sequel technology to completely sequence the whole genome of Talaromyces sp. DC2The genome study revealed that DC2 contains a total of 34.58 Mb spanned by 156 contigs, with a GC content of 46.5%. The identification and prediction of functional protein-coding genes, tRNA, and rRNA were comprehensively predicted and highly annotated using various BLAST databases, including non-redundant (Nr) protein sequence, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Clusters of Orthologous Groups (COG), and Carbohydrate-Active Enzymes (CAZy) databases. The genome of DC2 has a total of 149, 227, 65, 153, 53, and 6 genes responsible for cellulose, hemicellulose, lignin, pectin, chitin, starch, and inulin degradation, respectively. The Antibiotics and Secondary Metabolites Analysis Shell (AntiSMASH) analyses revealed that strain DC2 possesses 20 biosynthetic gene clusters responsible for producing secondary metabolites. The strain DC2 has also been found to harbor the DDC gene encoding aromatic L-amino acid decarboxylase enzyme. Conclusively, this study has provided a comprehensive understanding of the processes involved in secondary metabolites and the ability of the Talaromyces sp. DC2 strain to degrade plant cell walls.

Plant Heterotrophic Cultures: No Food, No Growth

Plant cells are capable of uptaking exogenous organic substances. This inherited trait allows the development of heterotrophic cell cultures in various plants. The most common of them are Nicotiana tabacum and Arabidopsis thaliana. Plant cells are widely used in academic studies and as factories for valuable substance production. The repertoire of compounds supporting the heterotrophic growth of plant cells is limited. The best growth of cultures is ensured by oligosaccharides and their cleavage products. Primarily, these are sucrose, raffinose, glucose and fructose. Other molecules such as glycerol, carbonic acids, starch, and mannitol have the ability to support growth occasionally, or in combination with another substrate. Culture growth is accompanied by processes of specialization, such as elongation growth. This determines the pattern of the carbon budget. Culture ageing is closely linked to substrate depletion, changes in medium composition, and cell physiological rearrangements. A lack of substrate leads to starvation, which results in a decrease in physiological activity and the mobilization of resources, and finally in the loss of viability. The cause of the instability of cultivated cells may be the non-optimal metabolism under cultural conditions or the insufficiency of internal regulation.

Genome-wide identification of NAC transcription factors and regulation of monoterpenoid indole alkaloid biosynthesis in Catharanthus roseus

NAC transcription factors (TFs) are crucial to growth and defense responses in plants. Though NACs have been characterized for their role in several plants, comprehensive information regarding their role in Catharanthus roseus, a perennial ornamental plant, is lacking. Homology modelling was employed to identify and characterize NACs in C. roseus. In-vitro propagation of C. roseus plants was carried out using cell suspension and nodal culture and were elicited with two auxin-antagonists, 5-fluoro Indole Acetic Acid (5-F-IAA) and α-(phenyl ethyl-2-oxo)-Indole-Acetic-Acid (PEO-IAA) for the enhanced production of monoterpenoid indole alkaloids (MIAs) namely catharanthine, vindoline, and vinblastine. Analyses revealed the presence of 47 putative CrNAC genes in the C. roseus genome, primarily localized in the nucleus. Phylogenetic analysis categorized these CrNACs into eight clusters, demonstrating the highest synteny with corresponding genes in Camptotheca acuminata. Additionally, at least one defense or hormone-responsive cis-acting element was identified in the promoter region of all the putative CrNACs. Of the two elicitors, 5-F-IAA was effective at 200 µM to elicit a 3.07-fold increase in catharanthine, 2.76-fold in vindoline, and 2.4-fold in vinblastine production in nodal culture. While a relatively lower increase in MIAs was recorded in suspension culture. Validation of RNA-Seq by qRT-PCR showed upregulated expression of stress-related genes (CrNAC-07 and CrNAC-24), and downregulated expression of growth-related gene (CrNAC-25) in elicited nodal culture of C. roseus. Additionally, the expression of genes involved in the biosynthesis of MIAs was significantly upregulated upon elicitation. The current study provides the first report on the role of CrNACs in regulating the biosynthesis of MIAs.

Endophytic fungi mediates production of bioactive secondary metabolites via modulation of genes involved in key metabolic pathways and their contribution in different biotechnological sector

Endophytic fungi stimulate the production of an enormous number of bioactive metabolites in medicinal plants and affect the different steps of biosynthetic pathways of these secondary metabolites. Endophytic fungi possess a number of biosynthetic gene clusters that possess genes for various enzymes, transcription factors, etc., in their genome responsible for the production of secondary metabolites. Additionally, endophytic fungi also modulate the expression of various genes responsible for the synthesis of key enzymes involved in metabolic pathways of such as HMGR, DXR, etc. involved in the production of a large number of phenolic compounds as well as regulate the expression of genes involved in the production of alkaloids and terpenoids in different plants. This review aims to provide a comprehensive overview of gene expression related to endophytes and their impact on metabolic pathways. Additionally, this review will emphasize the studies done to isolate these secondary metabolites from endophytic fungi in large quantities and assess their bioactivity. Due to ease in synthesis of secondary metabolites and their huge application in the medical industry, these bioactive metabolites are now being extracted from strains of these endophytic fungi commercially. Apart from their application in the pharmaceutical industry, most of these metabolites extracted from endophytic fungi also possess plant growth-promoting ability, bioremediation potential, novel bio control agents, sources of anti-oxidants, etc. The review will comprehensively shed a light on the biotechnological application of these fungal metabolites at the industrial level.

Indispensable Biomolecules for Plant Defense Against Pathogens: NBS-LRR and "nitrogen pool" Alkaloids

In a complex natural environment, plants have evolved intricate and subtle defense response regulatory mechanisms for survival. Plant specific defenses, including the disease resistance protein nucleotide-binding site leucine-rich repeat (NBS-LRR) protein and metabolite derived alkaloids, are key components of these complex mechanisms. The NBS-LRR protein can specifically recognize the invasion of pathogenic microorganisms to trigger the immune response mechanism. Alkaloids, synthesized from amino acids or their derivatives, can also inhibit pathogens. This study reviews NBS-LRR protein activation, recognition, and downstream signal transduction in plant protection, as well as the synthetic signaling pathways and regulatory defense mechanisms associated with alkaloids. In addition, we clarify the basic regulation mechanism and summarize their current applications and the development of future applications in biotechnology for these plant defense molecules. Studies on the NBS-LRR protein and alkaloid plant disease resistance molecules may provide a theoretical foundation for the cultivation of disease resistant crops and the development of botanical pesticides.

Biosynthesis of anticancer phytochemical compounds and their chemistry

Cancer is a severe health issue, and cancer cases are rising yearly. New anticancer drugs have been developed as our understanding of the molecular mechanisms behind diverse solid tumors, and metastatic malignancies have increased. Plant-derived phytochemical compounds target different oncogenes, tumor suppressor genes, protein channels, immune cells, protein channels, and pumps, which have attracted much attention for treating cancer in preclinical studies. Despite the anticancer capabilities of these phytochemical compounds, systemic toxicity, medication resistance, and limited absorption remain more significant obstacles in clinical trials. Therefore, drug combinations of new phytochemical compounds, phytonanomedicine, semi-synthetic, and synthetic analogs should be considered to supplement the existing cancer therapies. It is also crucial to consider different strategies for increased production of phytochemical bioactive substances. The primary goal of this review is to highlight several bioactive anticancer phytochemical compounds found in plants, preclinical research, their synthetic and semi-synthetic analogs, and clinical trials. Additionally, biotechnological and metabolic engineering strategies are explored to enhance the production of bioactive phytochemical compounds. Ligands and their interactions with their putative targets are also explored through molecular docking studies. Therefore, emphasis is given to gathering comprehensive data regarding modern biotechnology, metabolic engineering, molecular biology, and in silico tools.

Abiotic Stresses Elicitation Potentiates the Productiveness of Cardoon Calli as Bio-Factories for Specialized Metabolites Production

Cultivated cardoon (Cynara cardunculus L. var altilis) is a Mediterranean traditional food crop. It is adapted to xerothermic conditions and also grows in marginal lands, producing a large biomass rich in phenolic bioactive metabolites and has therefore received attention for pharmaceutical, cosmetic and innovative materials applications. Cardoon cell cultures can be used for the biotechnological production of valuable molecules in accordance with the principles of cellular agriculture. In the current study, we developed an elicitation strategy on leaf-derived cardoon calli for boosting the production of bioactive extracts for cosmetics. We tested elicitation conditions that trigger hyper-accumulation of bioactive phenolic metabolites without compromising calli growth through the application of chilling and salt stresses. We monitored changes in growth, polyphenol accumulation, and antioxidant capability, along with transcriptional variations of key chlorogenic acid and flavonoids biosynthetic genes. At moderate stress intensity and duration (14 days at 50–100 mM NaCl) salt exerted the best eliciting effect by stimulating total phenols and antioxidant power without impairing growth. Hydroalcoholic extracts from elicited cardoon calli with optimal growth and bioactive metabolite accumulation were demonstrated to lack cytotoxicity by MTT assay and were able to stimulate pro-collagen and aquaporin production in dermal cells. In conclusion, we propose a “natural” elicitation system that can be easily and safely employed to boost bioactive metabolite accumulation in cardoon cell cultures and also in pilot-scale cell culture production.

Induction of Catharanthus roseus Secondary Metabolites When Calotropis procera Was Used as Bio-Stimulant

Available information associated with Calotropis procera posted its phytotoxic effect as bio-herbicide scarce works studied its stimulatory/nutritive effect. A pot experiment was performed to assess the validity of using Calotropis procera (C. procera) leaves extract as a bio-stimulant for the growth and quality of a medicinal plant Catharanthus roseus (C. roseus) evaluated by some physio-biochemical indices. Different types of C. procera leaves extracts (CLEs) (methanolic, cold water and autoclaved water extracts) were delivered by two different modes of application. The results revealed that application of CLEs as irrigation or foliar spraying caused a stimulation effect on C. roseus plant. Root and shoot length, dry and fresh weight were significantly improved due to CLEs applications. C. roseus bioactive molecules such as anthocyanins, phenolics, flavonoids, alkaloids, ascorbic acid, reduced glutathione and α-tocopherol were abundance increased significantly with CLEs applications. Reactive oxygen species (ROS) decreased explaining the involvement of CLEs in induction of antioxidant enzymes catalase, ascorbate peroxidase, polyphenol oxidase, guaiacol peroxidase and glutathione-S-transferase for modifying cell oxidative status witnessed by lower lipid peroxidation that kept below the untreated plants’ baseline reflected the improvement of growth and quality rather than phytotoxic effect. The promotion of wholesome-promoting secondary metabolites by CLEs was closely correlated to elevated phenylalanineammonialyase activity. The comparable efficient effect induced by all treatments might be judged by the relation between C. procera phytochemicals and C. roseus metabolism (donor-receiver relation). It is concluded that application of CLEs can be a promising approach for improving the yield and quality of plants despite using polluting fertilizers. The current investigation may provide a matrix for coming studies to seek illustration of numerous plants’ response to C. procera extracts.