Metabolic signatures provide novel insights to Picrorhiza kurroa adaptation along the altitude in Himalayan region

Proteomic and metabolomic insights into seed germination of Ferula assa-foetida

Cold stratification is known to affect the speed of seed germination; however, its regulation at the molecular level in Ferula assa-foetida remains ambiguous. Here, we used cold stratification (4 °C in the dark) to induce germination in F. assa-foetida and adopted a proteomic and metabolomic approach to understand the molecular mechanism of germination. Compared to the control, we identified 209 non-redundant proteins and 96 metabolites in germinated F. assa-foetida seed. Results highlight the common and unique regulatory mechanisms like signaling cascade, reactivation of energy metabolism, activation of ROS scavenging system, DNA repair, gene expression cascade, cytoskeleton, and cell wall modulation in F. assa-foetida germination. A protein-protein interaction network identifies 18 hub protein species central to the interactome and could be a key player in F. assa-foetida germination. Further, the predominant metabolic pathways like glucosinolate biosynthesis, arginine and proline metabolism, cysteine and methionine metabolism, aminoacyl-tRNA biosynthesis, and carotenoid biosynthesis in germinating seed may indicate the regulation of carbon and nitrogen metabolism is prime essential to maintain the physiology of germinating seedlings. The findings of this study provide a better understanding of cold stratification-induced seed germination, which might be utilized for genetic modification and traditional breeding of Ferula assa-foetida. SIGNIFICANCE: Seed germination is the fundamental checkpoint for plant growth and development, which has ecological significance. Ferula assa-foetida L., commonly known as "asafoetida," is a medicinal and food crop with huge therapeutic potential. To date, our understanding of F. assa-foetida seed germination is rudimentary. Therefore, studying the molecular mechanism that governs dormancy decay and the onset of germination in F. assa-foetida is essential for understanding the basic principle of seed germination, which could offer to improve genetic modification and traditional breeding.

Functional trait correlation network and proteomic analysis reveal multifactorial adaptation mechanisms to a climatic gradient associated with high altitude in the Himalayan region

Globally occurring changes in environmental conditions necessitate extending our knowledge of the system-level mechanisms underlying plant adaptation to multifactorial stress conditions or stress combinations. This is crucial for designing new strategies to maintain plant performance under simultaneous abiotic pressure. Here, we conducted our study at Rohtang Pass and sampled Picrorhiza kurroa leaves along high-altitude gradient (3400, 3800 and 4100 meters above sea level) in the western Himalayas. The results showed the functional traits associated with morpho-anatomical structures and eco-physiological performances are highly variable. The air temperature and relative humidity represent dominant environmental factors among others that significantly regulate plant's physiological performance by adjusting the functional traits in altitude-specific manner. A trait coordination network is developed among significantly altered plant functional traits, which reveals high-altitude associated trait-based adaptation. Moreover, it reveals leaf area shows the highest degree, while photochemical quenching reflects the weighted degree of centrality in the network. Proteomic analysis reveals various stress-responsive proteins, including antioxidants were accumulated to deal with combined stress factors. Furthermore, a high-altitudinal protein interaction network unravels key players of alpine plant adaptation processes. Altogether, these systems demonstrate a complex molecular interaction web extending the current knowledge of high-altitudinal alpine plant adaptation, particularly in an endangered medicinal herb, P. kurroa.

Altitudinal Variation on Metabolites, Elements, and Antioxidant Activities of Medicinal Plant Asarum

Asarum (Asarum sieboldii Miq. f. seoulense (Nakai) C. Y. Cheng et C. S. Yang) is a medicinal plant that contains asarinin and sesamin, which possess extensive medicinal value. The adaptation and distribution of Asarum's plant growth are significantly affected by altitude. Although most studies on Asarum have concentrated on its pharmacological activities, little is known about its growth and metabolites with respect to altitude. In this study, the physiology, ionomics, and metabolomics were investigated and conducted on the leaves and roots of Asarum along an altitude gradient, and the content of its medicinal components was determined. The results showed that soil pH and temperature both decreased along the altitude, which restricts the growth of Asarum. The accumulation of TOC, Cu, Mg, and other mineral elements enhanced the photosynthetic capacity and leaf plasticity of Asarum in high-altitude areas. A metabolomics analysis revealed that, at high altitude, nitrogen metabolism in leaves was enhanced, while carbon metabolism in roots was enhanced. Furthermore, the metabolic pathways of some phenolic substances, including syringic acid, vanillic acid, and ferulic acid, were altered to enhance the metabolism of organic acids. The study uncovered the growth and metabolic responses of Asarum to varying altitudes, providing a theoretical foundation for the utilization and cultivation of Asarum.

Jasmonic acid limits Rhizoctonia solani AG1-IA infection in rice by modulating reactive oxygen species homeostasis

Sheath blight disease of rice caused by a soil-borne fungal pathogen Rhizoctonia solani AG1-IA is one of the major threats to rice production globally. During host-pathogen interactions, reactive oxygen species (ROS) play an important role in pathogen virulence and plant defense. For example, necrotrophic pathogens induce ROS production to damage host cells, whereas the host can incite ROS to kill the pathogen. From the host perspective, it is essential to understand how the antioxidant machinery maintains a delicate balance of ROS to protect itself from its lethal effects. Here, we investigated the pathogen-induced accumulation of ROS and implicated damage in two rice genotypes (PR114, susceptible; ShB, moderately tolerant) varying in the level of susceptibility to R. solani AG1-IA. Compared to PR114, ShB exhibited a better antioxidant response and reasonably lesser oxidative damage. Further, we observed elevated levels of jasmonic acid (JA) in ShB, which was otherwise decreased in PR114 in response to pathogen infection. As depicted, an elevated level of JA was in agreement with the expression profiles of genes involved in its biosynthesis and signaling. To further ascertain if the heightened antioxidant response is JA-dependent or independent, methyl jasmonate (MeJA) was exogenously applied to PR114, and antioxidant response in terms of gene expression, enzyme activities, and oxidative damage was studied in R. solani infected samples. Surprisingly, the exogenous application of MeJA complemented the antioxidant response and reduced oxidative damage in PR114, thus suggesting that the antioxidant defense system is under transcriptional control of JA.

Single and interactive effects of variables associated with climate change on wheat metabolome

One of the key challenges linked with future food and nutritional security is to evaluate the interactive effect of climate variables on plants' growth, fitness, and yield parameters. These interactions may lead to unique shifts in the morphological, physiological, gene expression, or metabolite accumulation patterns, leading to an adaptation response that is specific to future climate scenarios. To understand such changes, we exposed spring wheat to 7 regimes (3 single and 4 combined climate treatments) composed of elevated temperature, the enhanced concentration of CO₂, and progressive drought stress corresponding to the predicted climate of the year 2100. The physiological and metabolic responses were then compared with the current climate represented by the year 2020. We found that the elevated CO₂ (eC) mitigated some of the effects of elevated temperature (eT) on physiological performance and metabolism. The metabolite profiling of leaves revealed 44 key metabolites, including saccharides, amino acids, and phenolics, accumulating contrastingly under individual regimes. These metabolites belong to the central metabolic pathways that are essential for cellular energy, production of biosynthetic pathways precursors, and oxidative balance. The interaction of eC alleviated the negative effect of eT possibly by maintaining the rate of carbon fixation and accumulation of key metabolites and intermediates linked with the Krebs cycle and synthesis of phenolics. Our study for the first time revealed the influence of a specific climate factor on the accumulation of metabolic compounds in wheat. The current work could assist in the understanding and development of climate resilient wheat by utilizing the identified metabolites as breeding targets for food and nutritional security.

A comparative metabolomic investigation in fruit sections of Citrus medica L. and Citrus maxima L. detecting potential bioactive metabolites using UHPLC-QTOF-IMS

The current study focused on targeted and non-targeted metabolomics of Citrus fruit parts (exocarp, mesocarp, endocarp, and seeds) to gain a comprehensive metabolomic insight. Sections of the Citrus fruit were preliminarily examined for proximate compositions (moisture, ash, fibre, fat, and protein). Whereas ultrasonication-assisted solvent extraction revealed a higher phenolic and flavonoid content at 80% (v/v) ethanolic medium, with the highest amount in the exocarp. Using targeted metabolomics, hesperidin (3307.25 mg/100 g), naringin (4803.73 mg/100 g) were detected in C. medica and C. maxima at greater levels, respectively. Further quantitative analysis revealed the presence of phenolic acids (gallic acid, trans-ferulic acid, p-coumaric acid, trans-cinnamic acid), and polymethoxyflavones (nobiletin, and tangeretin) and detected in the order of exocarp > mesocarp > endocarp > seeds. Using an untargeted metabolomics approach, metabolite discriminations among Citrus fruit sections were illustrated by Venn-diagram, heatmap, PCA, o-PLSDA, correlation matrices, and S-plot. UHPLC-QTOF-IMS revealed 48 metabolites including phenolics, vitamins, and amino acids. Furthermore, the METLIN database leads to the identification of 202 unknown metabolites. The metabolite biosynthesis and corresponding metabolite presence in Citrus fruit sections were confirmed using pathway enrichment and mass fragmentation analysis. Finally, potential biological activities were determined using in silico PASS software approach, and free radical scavenging potential was confirmed using in vitro assays for future preventive and therapeutic applications of the identified metabolites.

Swertia purpurascens Wall ethanolic extract mitigates hepatic fibrosis and restores hepatic hepcidin levels via inhibition of TGFβ/SMAD/NFκB signaling in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Swertia purpurascens Wall belongs to a well-known genus in traditional systems of medicine worldwide. In folklore, it is used to treat various ailments, including hepatic disorders, as an alternative to the endangered species Swertia chirayita. However, the therapeutic potential of Swertia purpurascens Wall against hepatic fibrosis has not been validated yet.

AIM OF THE STUDY

The present study was planned to evaluate the efficacy of the Swertia purpurascens Wall extract (SPE) against hepatic fibrosis and elucidate the underlying mechanism of action.

MATERIALS AND METHODS

The metabolite profiling of the SPE was done using UHPLC-QTOF-MS/MS. The acute oral toxicity study of SPE at 2 g/kg BW dose was done in rats. Further, the liver fibrosis was induced by the CCl₄ intoxication, and the efficacy of SPE at three doses (100, 200 and 400 mg/kg BW) was evaluated by studying biochemical parameters, histopathology, immunohistochemistry, qRT-PCR, western blotting and in silico analysis.

RESULTS

UHPLC-QTOF-MS/MS analysis revealed the presence of a total of 23 compounds in SPE. Acute oral toxicity study of SPE at 2 g/kg BW showed no harmful effects in rats. Further, the liver fibrosis was induced by the CCl₄ administration, and the efficacy of SPE was evaluated at three doses (100, 200 and 400 mg/kg BW). SPE treatment significantly improved the body weight gain, the relative liver weight, serum liver injury markers and endogenous antioxidant enzyme levels in the CCl₄-treated rats. SPE also recovered the altered liver histology and effectively reduced the fibrotic tissue deposition in the hepatic parenchyma. Further, SPE significantly inhibited the fibrotic (TGFβ, αSMA, SMADs and Col1A), proinflammatory markers (NFκB, TNFα and IL1β) and apoptosis in the liver tissue. Interestingly, SPE treatment also restored the altered hepcidin levels in the liver tissue. In silico study revealed the potential of various metabolites as drug candidates and their interaction with target proteins.

CONCLUSION

Altogether, SPE showed its therapeutic potential against CCl₄-induced hepatic fibrosis by restoring the hepatic hepcidin levels and inhibiting TGFβ/SMAD/NFκB signaling in rats.

Integrated Metabolomic and Transcriptomic Analysis of the Flavonoid Accumulation in the Leaves of Cyclocarya paliurus at Different Altitudes

Cyclocarya paliurus is a medicinal plant containing flavonoids, triterpenoids, polyphenolics, polysaccharides, and other compounds with diverse biological functions. C. paliurus is distributed across altitudes ranging from 400 to 1,000 m. However, little is known about the effect of altitude on metabolite accumulation in C. paliurus. Also, the biosynthetic pathway involved in flavonoid accumulation in C. paliurus has not been fully elucidated. In this study, mature leaves of C. paliurus growing at low altitude (280 m) and high altitude (920 m) were sampled and subjected to metabolomic and transcriptomic analyses. The flavonoid content and composition were higher in the leaves of C. paliurus collected at high altitude than in those collected at low altitude. Most of the differentially accumulated metabolites (DAMs) were enriched in "flavone and flavonol biosynthesis." The significant differentially expressed genes (DEGs) between low and high altitudes were mainly enriched in "biological process." The most heavily enriched KEGG pathway was related to the subcategory "Oxidative phosphorylation," indicating that complicated biological processes are involved in the response of C. paliurus to harsh environmental factors. High UV-light might be the main influencing factor among the harsh environmental factors found in high altitudes. Integrated analysis of metabolomic and transcriptomic data showed that 31 flavonoids were significantly correlated with 227 DEGs, resulting in 412 related pairs (283 positive and 129 negative) between the DEGs and flavonoids. The possible mechanisms underlying the differentially accumulation of flavonoids at different altitude might be due to variations in transport and relocation of flavonoids in C. paliurus leaves, but not different flavonoid biosynthesis pathways. The up-regulation of genes related to energy and protein synthesis might contribute to flavonoid accumulation at high altitudes. This study broadens our understanding of the effect of altitude on metabolite accumulation and biosynthesis in C. paliurus.

In-depth assembly of organ and development dissected Picrorhiza kurroa proteome map using mass spectrometry

BACKGROUND

Picrorhiza kurroa Royle ex Benth. being a rich source of phytochemicals, is a promising high altitude medicinal herb of Himalaya. The medicinal potential is attributed to picrosides i.e. iridoid glycosides, which synthesized in organ-specific manner through highly complex pathways. Here, we present a large-scale proteome reference map of P. kurroa, consisting of four morphologically differentiated organs and two developmental stages.

RESULTS

We were able to identify 5186 protein accessions (FDR < 1%) providing a deep coverage of protein abundance array, spanning around six orders of magnitude. Most of the identified proteins are associated with metabolic processes, response to abiotic stimuli and cellular processes. Organ specific sub-proteomes highlights organ specialized functions that would offer insights to explore tissue profile for specific protein classes. With reference to P. kurroa development, vegetative phase is enriched with growth related processes, however generative phase harvests more energy in secondary metabolic pathways. Furthermore, stress-responsive proteins, RNA binding proteins (RBPs) and post-translational modifications (PTMs), particularly phosphorylation and ADP-ribosylation play an important role in P. kurroa adaptation to alpine environment. The proteins involved in the synthesis of secondary metabolites are well represented in P. kurroa proteome. The phytochemical analysis revealed that marker compounds were highly accumulated in rhizome and overall, during the late stage of development.

CONCLUSIONS

This report represents first extensive proteomic description of organ and developmental dissected P. kurroa, providing a platform for future studies related to stress tolerance and medical applications.

Altitudinal Variation of Metabolites, Mineral Elements and Antioxidant Activities of Rhodiola crenulata (Hook.f. & Thomson) H.Ohba

Rhodiolacrenulata (Hook.f. & Thomson) H.Ohba is an alpine medicinal plant that can survive in extreme high altitude environments. However, its changes to extreme high altitude are not yet clear. In this study, the response of Rhodiola crenulata to differences in altitude gradients was investigated through chemical, ICP-MS and metabolomic methods. A targeted study of Rhodiola crenulata growing at three vertical altitudes revealed that the contents of seven elements Ca, Sr, B, Mn, Ni, Cu, and Cd, the phenolic components, the ascorbic acid, the ascorbic acid/dehydroascorbate ratio, and the antioxidant capacity were positively correlated with altitude, while the opposite was true for total ascorbic acid content. Furthermore, 1165 metabolites were identified: flavonoids (200), gallic acids (30), phenylpropanoids (237), amino acids (100), free fatty acids and glycerides (56), nucleotides (60), as well as other metabolites (482). The differential metabolite and biomarker analyses suggested that, with an increasing altitude: (1) the shikimic acid-phenylalanine-phenylpropanoids-flavonoids pathway was enhanced, with phenylpropanoids upregulating biomarkers much more than flavonoids; phenylpropanes and phenylmethanes upregulated, and phenylethanes downregulated; the upregulation of quercetin was especially significant in flavonoids; upregulation of condensed tannins and downregulation of hydrolyzed tannins; upregulation of shikimic acids and amino acids including phenylalanine. (2) significant upregulation of free fatty acids and downregulation of glycerides; and (3) upregulation of adenosine phosphates. Our findings provide new insights on the responses of Rhodiola crenulata to extreme high altitude adversity.

A Comprehensive Search of the Primary and Secondary Metabolites and Radical Scavenging Potential of Trillium govanianum Wall. ex D. Don

Trillium govanianum rhizomes are traditionally consumed as a raw powder and decoction for the treatment of health complications. Hence, the present study aimed to investigate whether aqueous and alcoholic extracts of T. govanianum rhizomes under hot and cold extraction conditions have similar or dissimilar chemical, nutrient, and antioxidant profiles. The total phenolics, flavonoids, carbohydrates, proteins, fats, and energy values were estimated in all the conditionally prepared samples. The total phenolics (21.23±1.4 mg GAE/g extract), flavonoids (70.57±3.24 mg RE/g extract) were found higher in hot ethanolic extract (TGHEt), while cold water extract (TGGC) showed higher nutrients including amino acids (10.545±0.219 mg/g) and nucleosides (1.803±0.018 mg/g). The nutrient energy value (2.60 and 2.49 Kcal/g extract) was higher in cold and hot ethanolic extracts. Further, TGHEt scavenged the DPPH^. (IC₅₀ ; 870±22 μg/mL) and ABTS^.+ (IC₅₀ ; 80±1.49 μg/mL) effectively and proved its highest antioxidant activity compared to other samples. In LC/MS/MS-based metabolite profiling, twenty-six metabolites (fatty acids, steroidal saponins, triterpene saponins, ecdysteroid hormones) were confirmed with mass fragmentation and literature, while one hundred nine metabolites were identified using the METLIN database. The principal component analysis showed clustering of hot condition extracts while cold extracts were differentially located in quadrants. The heatmaps exhibited the associations and differences between metabolite composition, solvents, and extraction conditions. The identified metabolites speculatively predicted the biosynthesis pathway of T. govanianum. Findings also illustrated that T. govanianum is a source of bioactive nutritional components and saponins. The current metabolite profiling of T. govanianum will help in its agricultural and biotechnological interventions for higher quality produce.

Evaluating Peptides of Picrorhiza kurroa and Their Inhibitory Potential against ACE, DPP-IV, and Oxidative Stress

Picrorhiza kurroa Royle ex Benth. is a high-altitude plant having great medicinal value. However, its medicinal value at the peptide level is still unknown, which limits its utility in the development of peptide-based therapeutics. Here, we identify 65 peptides fromP. kurroa hydrolysate. Sequence analysis suggests that one novel bioactive peptide, ASGLCPEEAVPRR (BP1), has antioxidant potential and shows angiotensin-converting enzyme (ACE) and dipeptidyl peptidase-IV (DPP-IV) inhibitory activities. The molecular docking study showed that BP1 has a lower binding energy and strong affinity toward active pockets of ACE and DPP-IV, which explains its higher ACE [IC₅₀ = 59.90 ± 9.52 μg/mL (43.40 μM)] and DPP-IV [IC₅₀ = 3.04 ± 0.26 μg/mL (2.2 μM)] inhibitory activities. BP1 protects HEK293 cells from H₂O₂-induced oxidative damage by inhibiting intracellular reactive oxygen species (ROS) and malondialdehyde accumulation and activating the intrinsic antioxidant defense system. Additionally, phase-contrast microscopy studies revealed that pre-treatment of BP1 to HEK293 cells before exposure to H₂O₂ retains the normal morphology and blocks apoptosis. Furthermore, it also suppresses ROS-induced mitochondrial apoptosis via restoring the mitochondrial membrane potential (ΔΨm) and inhibiting caspase 3/7 activity. Therefore, BP1 has antioxidant potential and ACE and DPP-IV inhibitory activities that could be used for peptide-based formulation(s) in pharmaceuticals to treat diabetes, cardiovascular diseases, and other diseases associated with ROS.

Soil and Leaf Nutrients Drivers on the Chemical Composition of the Essential Oil of Siparuna muricata (Ruiz & Pav.) A. DC. from Ecuador

Chemical compositions of plants are affected by the initial nutrient contents in the soil and climatic conditions; thus, we analyzed for the first time the effects of soil and leaf nutrients on the compositions of the essential oils (EOs) of Siparuna muricata in four different localities in Ecuador. EOs were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC/MS) and a gas chromatography/flame ionization detector (GC/FID). Enantiomeric distribution by GC/MS was determined, modifying the enantiomeric separation of β-pinene, limonene, δ-elemene, β-bourbonene, cis-cadina-1 (6), 4-diene and atractylone. A total of 44 compounds were identified. The most representative for L1 were guaiol, atractylone and 4-diene; for L2, cis-cadina-1(6),4-diene and myrcene; for L3, atractylone, myrcene and germacrene B; and finally, L4 germacrene B, myrcene and cis-cadina-1(6),4-diene. Correlations between soil- leaf chemical elements such as Al, Ca, Fe, Mg, Mn, N and Si in the different localities were significant with chemical composition of the essential oil of Siparuna muricata; however, correlations between soil and leaf K, P, and Na were not significant. Cluster and NMDS analysis showed high dissimilarity values of secondary metabolites between four localities related with changes in soil- leaf nutrients. Thus, the SIMPER routine revealed that not all secondary metabolites contribute equally to establishing the differences in the four localities, and the largest contributions are due to differences in guaiol, cis-cadina-1(6),4-diene, atractylone and germacrene. Our investigation showed for the first time the influences of altitude and soil- leaf chemical elements in the chemical composition of the EOs of S. muricata.