Fungal endophytes attune withanolide biosynthesis in Withania somnifera, prime to enhanced withanolide A content in leaves and roots

Unraveling endophytic diversity in dioecious Siraitia grosvenorii: implications for mogroside production

Host and tissue-specificity of endophytes are important attributes that limit the endophyte application on multiple crops. Therefore, understanding the endophytic composition of the targeted crop is essential, especially for the dioecious plants where the male and female plants are different. Here, efforts were made to understand the endophytic bacterial composition of the dioecious Siraitia grosvenorii plant using 16S rRNA amplicon sequencing. The present study revealed the association of distinct endophytic bacterial communities with different parts of male and female plants. Roots of male and female plants had a higher bacterial diversity than other parts of plants, and the roots of male plants had more bacterial diversity than the roots of female plants. Endophytes belonging to the phylum Proteobacteria were abundant in all parts of male and female plants except male stems and fruit pulp, where the Firmicutes were most abundant. Class Gammaproteobacteria predominated in both male and female plants, with the genus Acinetobacter as the most dominant and part of the core microbiome of the plant (present in all parts of both, male and female plants). The presence of distinct taxa specific to male and female plants was also identified. Macrococcus, Facklamia, and Propionibacterium were the distinct genera found only in fruit pulp, the edible part of S. grosvenorii. Predictive functional analysis revealed the abundance of enzymes of secondary metabolite (especially mogroside) biosynthesis in the associated endophytic community with predominance in roots. The present study revealed bacterial endophytic communities of male and female S. grosvenorii plants that can be further explored for monk fruit cultivation, mogroside production, and early-stage identification of male and female plants. KEY POINTS: • Male and female Siraitia grosvenorii plants had distinct endophytic communities • The diversity of endophytic communities was specific to different parts of plants • S. grosvenorii-associated endophytes may be valuable for mogroside biosynthesis and monk fruit cultivation.

Characterization of an antimony-resistant fungus Sarocladium kiliense ZJ-1 and its potential as an antimony bio-remediator

Antimony (Sb) is a toxic metalloid widely distributed in the natural environments. Microorganisms, especially fungi, could serve as ideal biomaterials for bioremediation of Sb-polluted soils and waters. In this study, we isolated an antimony-resistant fungus, Sarocladium kiliense ZJ-1, from a slag sample collected in Xikuangshan Sb mine in P. R. China. ZJ-1 showed an extremely high resistance to Sb, with a MIC level of > 175 mM for arsenite [Sb(Ⅲ)] and 40 mM for arsenate [Sb(V)]. Whole genomic analysis identified multiple Sb (Ⅲ)- and/or As(Ⅲ)-resistant genes on ZJ-1's genome, which may partially explain its hyper-resistance to Sb. The potential of ZJ-1 in removing Sb from Sb(Ⅲ) or Sb(V) solutions was also quantified. The average biosorption capacity of ZJ-1 for Sb(Ⅲ) and Sb(V) is 635.14 mg/g and 149.65 mg/g, respectively, in Sb aqueous solutions with an initial concentration of 2000 mg/L (16.43 mM). Besides, almost 99% of Sb(Ⅲ) in the growing system was removed with an initial concentration of 500 mg/L (4.11 mM). Furthermore, Fourier transformation infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used to probe the Sb adsorption mechanism on ZJ-1, and -OH, -NH2, -COOH, C-O and C-O-C were found to be the main surface functional groups of ZJ-1 cells to adsorb Sb.

Copper and iron metal resistant rhizospheric bacteria boost the plant growth and bacoside A content in Bacopa monnieri under stress conditions

Bacteria that enhance plant growth and development and are found in the vicinity of roots are referred to as plant growth-promoting rhizobacteria. Some beneficial bacteria help plant tolerance to many hazardous chemical elements. In this context, Cupriavidus basilensis , Novosphingobium humi , Bacillus zanthoxyli , Bacillus sp., Paenibacillus alvei , Ancylobacter aquaticus and Ralstonia syzygii metal-tolerant rhizospheric bacteria were isolated from rhizospheric soil associated with Bacopa monnieri . The beneficial effects of rhizospheric bacteria on B. monnieri plant physiology and biochemical responses were investigated under pot conditions at two levels (100μM and 500μM) of CuSO4 or FeCl3 . N. humi , A. aquaticus and R. syzygii bacterial strains were associated with significantly increased height and biomass under normal and stress conditions. An assay for indole acetic acid in isolated rhizospheric bacteria found differential secretion except Bacillus zanthoxyli . Bacoside A is a major phytocompound in B. monnieri with medicinal value; maximum induction was observed in the R. syzygii treatment. High concentration of copper and iron salts negatively influenced height, biomass and photosynthetic pigments; however N. humi , A. aquaticus , Bacilllus sp. and R. syzygii beneficial bacterial helped plants under stress conditions. Moreover, a significant enhancement in chlorophyll a and b was noticed in C. basilensis , B. zanthoxyli , Bacilllus sp., P. alvei and R. syzygii treatments, without much influence on carotenoid levels. Therefore, the present study emphasises the importance of isolating plant growth-promoting rhizobacteria for use in bacopa plants exposed to metals such as copper and iron in soil.

Perspectives and potential applications of endophytic microorganisms in cultivation of medicinal and aromatic plants

Ensuring food and nutritional security, it is crucial to use chemicals in agriculture to boost yields and protect the crops against biotic and abiotic perturbations. Conversely, excessive use of chemicals has led to many deleterious effects on the environment like pollution of soil, water, and air; loss of soil fertility; and development of pest resistance, and is now posing serious threats to biodiversity. Therefore, farming systems need to be upgraded towards the use of biological agents to retain agricultural and environmental sustainability. Plants exhibit a huge and varied niche for endophytic microorganisms inside the planta, resulting in a closer association between them. Endophytic microorganisms play pivotal roles in plant physiological and morphological characteristics, including growth promotion, survival, and fitness. Their mechanism of action includes both direct and indirect, such as mineral phosphate solubilization, fixating nitrogen, synthesis of auxins, production of siderophore, and various phytohormones. Medicinal and aromatic plants (MAPs) hold a crucial position worldwide for their valued essential oils and several phytopharmaceutically important bioactive compounds since ancient times; conversely, owing to the high demand for natural products, commercial cultivation of MAPs is on the upswing. Furthermore, the vulnerability to various pests and diseases enforces noteworthy production restraints that affect both crop yield and quality. Efforts have been made towards enhancing yields of plant crude drugs by improving crop varieties, cell cultures, transgenic plants, etc., but these are highly cost-demanding and time-consuming measures. Thus, it is essential to evolve efficient, eco-friendly, cost-effective simpler approaches for improvement in the yield and health of the plants. Harnessing endophytic microorganisms as biostimulants can be an effective and alternative step. This review summarizes the concept of endophytes, their multidimensional interaction inside the host plant, and the salient benefits associated with endophytic microorganisms in MAPs.

Bacillus cereus Enhanced Medicinal Ingredient Biosynthesis in Glycyrrhiza uralensis Fisch. Under Different Conditions Based on the Transcriptome and Polymerase Chain Reaction Analysis

The aim of this study was to evaluate the effect of Bacillus cereus (B. cereus) on the seedling growth and accumulation of medicinal ingredients of Glycyrrhiza uralensis Fisch. (G. uralensis) under control and salt stress conditions. Our results revealed the different effects of B. cereus on the seedling growth and accumulation of medicinal ingredients particularly in different conditions based on the transcriptome and polymerase chain reaction (PCR) analysis. Under the control condition, B. cereus significantly increased the expression level of the β-AS, SQS, CHS, LUS, UGAT, CYP72A154, and CYP88D6 genes and liquiritigenin content. Under salt stress, B. cereus significantly increased root length and lateral root number of G. uralensis seedlings, the expression level of HMGR, β-AS, CHS, LUS, UGAT, CYP72A154, CYP88D6, and SE genes, and the contents of glycyrrhizic acid and glycyrrhetinic acid. Notably, the effect of B. cereus on the seedling growth and the medicinal ingredient biosynthesis was different under control and salt stress conditions. Specifically, the effect of B. cereus on the seedling growth under salt stress was greater than that under the control condition. Moreover, B. cereus increased liquiritigenin content under the control condition, which is closely related to flavone and flavonol biosynthesis, while it increased the contents of glycyrrhizic acid and glycyrrhetinic acid under salt stress, which is closely related to phenylpropanoid biosynthesis, and the MVA pathway is also involved. All in all, endophytes B. cereus could be used as a sustainable tool to develop effective bioinoculants to enhance the contents of medicinal ingredients in G. uralensis.

Isolation and Phytochemical Screening of Endophytic Fungi Isolated from Medicinal Plant Mappia foetida and Evaluation of Its In Vitro Cytotoxicity in Cancer

Isolated endophyte fungi from Mappia foetida have been explored as a potential source for the mass production of anticancer drug lead compounds in the current study. Since medical plants are not feasible economically for mass production of bioactive pharmaceutical important molecules using plant tissue culture due to factors like media design and fungal contamination, endophyte fungal mass culture have been an alternative for the relatively easy and inexpensive production. Two endophytic fungi isolated, Alternaria alternata and Fusarium species were mass cultured and their prepared alcoholic extract subjected to standard procedures to identify the phytochemical screening by gas chromatography-mass spectrometry (GCMS), high-performance liquid chromatography (HPLC), UV visible spectrophotometry (UV-VIS), and Fourier transform infrared spectroscopy (FTIR). GC-MS analysis revealed the presence of three major compounds in the extracts. The phytochemical screening confirmed the presence of an anticancer compound (camptothecin) in their extract. Moreover, the dose-dependent anticancer activity of ethanol extract was demonstrated against cervical carcinoma (HeLa), breast carcinoma (MCF-7), non-small cell lung carcinoma (H1975), and hepatocellular carcinoma cell line (Hep G2) by MTT assay where doxorubicin was used as the positive control. Furthermore, the microscopic examination also confirmed the cytotoxic effect of extract of endophytic fungi Alternaria alternata and Fusarium species against tested cancer cells. Hence, endophytic fungi Alternaria alternata and Fusarium species might be exploited for mass production of phytochemicals having anticancer activity.

Phytochemical Screening and Bioactivity Studies of Endophytes Cladosporium sp. Isolated from the Endangered Plant Vateria Indica Using In Silico and In Vitro Analysis

Vateria indica is persistent tree used in Unani sources for the medication and classified as critically endangered. Thus, endophytes for alternative methods to explore these endangered Plants having rich source pharmaceuticals' active molecules for drug development and production. Endophytes comprises unexplored microbes as a potential source of rich pharmaceutically bioactive compounds attributable to their relationship with the host. In the current study, we have isolated endophyte fungi Cladosporium from the plant Vateria indica and performed phytochemical screening of its ethanolic extract to detect the phytochemicals using thin layer chromatography (TLC), gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), UV-visible spectrophotometry (UV-VIS), and Fourier transform infrared spectroscopy (FTIR). GC-MS analysis revealed the presence of an anticancer compound hydroxymethyl colchicine, antioxidant compound benzoic acid, and antimicrobial 2-(4-chlorophenoxy)-5-nitro in endophyte fungal extract of plant Vateria indica. Moreover, in silico analysis of bioactive compounds identified by GC-MS analysis using the Autodock Vina and SwissADME confirmed excellent anticancer activity methanone, [4-amino-2-[(phenylmethyl) amino]-5-thiazolyl] (4-fluorophenyl)- and hydroxymethyl colchicine against 6VO4 (Bfl-1 protein) as per Lipinski rule. Furthermore, we also demonstrated the excellent antioxidant of endophytic extract compared to plant extract by DPPH and ABTS assay, as well as antimicrobial activity against both Gram (+ ve) and Gram (- ve) bacteria. Moreover, the endophytic extract also showed its antimitotic activity with a mitotic index of 65.32, greater than the plant extract of 32.56 at 10 mg/ml. Thus endophytic fungi Cladosporium species isolated from plant Vateria indica might be used as a potential source for phytochemical anticancer hydroxymethyl colchicine, an antioxidant benzoic acid, and antimicrobial 2-(4-chlorophenoxy)-5-nitro.

Natural Products from Physalis alkekengi L. var. franchetii (Mast.) Makino: A Review on Their Structural Analysis, Quality Control, Pharmacology, and Pharmacokinetics

The calyxes and fruits of Physalis alkekengi L. var. franchetii (Mast.) Makino (P. alkekengi), a medicinal and edible plant, are frequently used as heat-clearing and detoxifying agents in thousands of Chinese medicine prescriptions. For thousands of years in China, they have been widely used in clinical practice to treat throat disease, hepatitis, and bacillary dysentery. This systematic review summarizes their structural analysis, quality control, pharmacology, and pharmacokinetics. Furthermore, the possible development trends and perspectives for future research studies on this medicinal plant are discussed. Relevant information on the calyxes and fruits of P. alkekengi was collected from electronic databases, Chinese herbal classics, and Chinese Pharmacopoeia. Moreover, information was collected from ancient documents in China. The components isolated and identified in P. alkekengi include steroids, flavonoids, phenylpropanoids, alkaloids, nucleosides, terpenoids, megastigmane, aliphatic derivatives, organic acids, coumarins, and sucrose esters. Steroids, particularly physalins and flavonoids, are the major characteristic and bioactive ingredients in P. alkekengi. According to the literature, physalins are synthesized by the mevalonate and 2-C-methyl-d-erythritol-4-phosphate pathways, and flavonoids are synthesized by the phenylpropanoid pathway. Since the chemical components and pharmacological effects of P. alkekengi are complex and varied, there are different standards for the evaluation of its quality and efficacy. In most cases, the analysis was performed using high-performance liquid chromatography coupled with ultraviolet detection. A pharmacological study showed that the crude extracts and isolated compounds from P. alkekengi had extensive in vitro and in vivo biological activities (e.g., anti-inflammatory, anti-tumor, immunosuppressive, antibacterial, anti-leishmanial, anti-asthmatic, anti-diabetic, anti-oxidative, anti-malarial, anti-Alzheimer's disease, and vasodilatory). Moreover, the relevant anti-inflammatory and anti-tumor mechanisms were elucidated. The reported activities indicate the great pharmacological potential of P. alkekengi. Similarly, studies on the pharmacokinetics of specific compounds will also contribute to the progress of clinical research in this setting.

Biotransformation ability of endophytic fungi: from species evolution to industrial applications

Abstract

Increased understanding of the interactions between endophytic fungi and plants has led to the discovery of a new generation of chemical compounds and processes between endophytic fungi and plants. Due to the long-term co-evolution between fungal endophytes and host plants, endophytes have evolved special biotransformation abilities, which can have critical consequences on plant metabolic processes and their composition. Biotransformation or bioconversion can impact the synthesis and decomposition of hormones, sugars, amino acids, vitamins, lipids, proteins, and various secondary metabolites, including flavonoids, polysaccharides, and terpenes. Endophytic fungi produce enzymes and various bioactive secondary metabolites with industrial value and can degrade or sequester inorganic and organic small molecules and macromolecules (e.g., toxins, pollutants, heavy metals). These fungi also have the ability to cause highly selective catalytic conversion of high-value compounds in an environmentally friendly manner, which can be important for the production/innovation of bioactive molecules, food and nutrition, agriculture, and environment. This work mainly summarized recent research progress in this field, providing a reference for further research and application of fungal endophytes.

Key points

•The industrial value of degradation of endophytes was summarized.

• The commercial value for the pharmaceutical industry is reviewed.

Graphical abstract

Harnessing the Phytotherapeutic Treasure Troves of the Ancient Medicinal Plant Azadirachta indica (Neem) and Associated Endophytic Microorganisms

Azadirachta indica, commonly known as neem, is an evergreen tree of the tropics and sub-tropics native to the Indian subcontinent with demonstrated ethnomedicinal value and importance in agriculture as well as in the pharmaceutical industry. This ancient medicinal tree, often called the "wonder tree", is regarded as a chemical factory of diverse and complex compounds with a plethora of structural scaffolds that is very difficult to mimic by chemical synthesis. Such multifaceted chemical diversity leads to a fantastic repertoire of functional traits, encompassing a wide variety of biological activity and unique modes of action against specific and generalist pathogens and pests. Until now, more than 400 compounds have been isolated from different parts of neem including important bioactive secondary metabolites such as azadirachtin, nimbidin, nimbin, nimbolide, gedunin, and many more. In addition to its insecticidal property, the plant is also known for antimicrobial, antimalarial, antiviral, anti-inflammatory, analgesic, antipyretic, hypoglycaemic, antiulcer, antifertility, anticarcinogenic, hepatoprotective, antioxidant, anxiolytic, molluscicidal, acaricidal, and antifilarial properties. Notwithstanding the chemical and biological virtuosity of neem, it has also been extensively explored for associated microorganisms, especially a class of mutualists called endophytic microorganisms (or endophytes). More than 30 compounds, including neem "mimetic" compounds, have been reported from endophytes harbored in the neem trees in different ecological niches. In this review, we provide an informative and in-depth overview of the topic that can serve as a point of reference for an understanding of the functions and applications of a medicinal plant such as neem, including associated endophytes, within the overall theme of phytopathology. Our review further exemplifies the already-noted current surge of interest in plant and microbial natural products for implications both within the ecological and clinical settings, for a more secure and sustainable future.

Endophytic Penicillium species and their agricultural, biotechnological, and pharmaceutical applications

Penicillium genus constituted by over 200 species is one of the largest and fascinating groups of fungi, particularly well established as a source of antibiotics. Endophytic Penicillium has been reported to colonize their ecological niches and protect their host plant against multiples stresses by exhibiting diverse biological functions that can be exploited for countless applications including agricultural, biotechnological, and pharmaceutical. Over the past 2 decades, endophytic Penicillium species have been investigated beyond their antibiotic potential and numerous applications have been reported. We comprehensively summarized in this review available data (2000-2019) regarding bioactive compounds isolated from endophytic Penicillium species as well as the application of these fungi in multiple agricultural and biotechnological processes. This review has shown that a very large number (131) of endophytes from this genus have been investigated so far and more than 280 compounds exhibiting antimicrobial, anticancer, antiviral, antioxidants, anti-inflammatory, antiparasitics, immunosuppressants, antidiabetic, anti-obesity, antifibrotic, neuroprotective effects, and insecticidal and biocontrol activities have been reported. Moreover, several endophytic Penicillium spp. have been characterized as biocatalysts, plant growth promoters, phytoremediators, and enzyme producers. We hope that this review summarizes the status of research on this genus and will stimulate further investigations.

Innate endophytic fungus, Aspergillus terreus as biotic elicitor of withanolide A in root cell suspension cultures of Withania somnifera

In the present study, root cell suspension cultures of W. somnifera were elicited with mycelial extract (1% w/v) and culture filtrate (5% v/v) of their native endophytic fungus Aspergillus terreus 2aWF in shake flask. Culture filtrate of A. terreus 2aWF significantly elicits withanolide A at 6H (12.20 ± 0.52 µg/g FCB). However, with A. terreus 2aWF mycelial extract, withanolide A content was higher at 24H (10.29 µg/g FCB). Withanolide A content was maximum with salicylic acid (0.1 mM) treatment at 24H (8.3 ± 0.20 µg/g FCB). Further, expression analysis of withanolide pathway genes, hydrogen peroxide production, and lipid peroxidation was carried out after 48H of elicitation with 2aWF mycelial extract and culture filtrate. The expression levels of withanolides biosynthetic pathway genes, viz. HMGR, DXR, FPPS, SQS, SQE, CAS, SMT1, STE1 and CYP710A1 were quantified by real time PCR at 48H of elicitation. In all the treatments, the expression levels of key genes were significantly upregulated as compared to untreated suspension cells. Hydrogen peroxide was noticeably enhanced in SA, mycelia extract and culture filtrate, at 20% (115 ± 4.40 nM/g FCB), 42% (137.5 ± 3.62 nM/g FCB), and 27% (122.8 ± 1.25 nM/g FCB) respectively; however, lipid peroxidation was 0.288 ± 0.014, 0.305 ± 0.041 and 0.253 ± 0.007 (µM/gm FCB) respectively, higher than the control (0.201 ± 0.007 µM/gm FCB).