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

Plastidial metabolites and retrograde signaling: A case study of MEP pathway intermediate MEcPP that orchestrates plant growth and stress responses

Plants are frequently exposed to environmental stresses. In a plant cell, chloroplast acts as machinery that rapidly senses changing environmental conditions and coordinates with the nucleus and other subcellular organelles by exchanging plastidial metabolites, proteins/peptides, or lipid derivatives, some of which may act as retrograde signals. These specific plastidial metabolites include carotenoid derivatives, isoprenes, phosphoadenosines, tetrapyrroles, phytohormone (like salicylic acid), and reactive electrophile species (RES), which mediate retrograde communications to sustain stress conditions. The methylerythritol phosphate (MEP) pathway is an essential and evolutionarily conserved isoprenoid biosynthetic pathway operating in bacteria and plastids, synthesizing metabolites such as terpenoids, gibberellins, abscisic acid, phytol chain of chlorophyll, carotenoids, tocopherols, and glycosides. The MEP pathway is susceptible to oxidative stress, which results in the overaccumulation of its intermediates, such as methylerythritol cyclodiphosphate (MEcPP). Recent studies revealed that under stress conditions, leading to its accumulation, MEcPP mediates retrograde signaling that alters the nuclear gene expression, leading to growth inhibition and acclimation. This review covers aspects of its generation, signaling, mechanism of action, and interplay with other factors to acquire adaptive responses during stress conditions. The review highlights the importance of plastids as sensors of stress and plastidial metabolites as retrograde signals communicating with nucleus and other sub-cellular organelles to regulate plants' response to different stress conditions.

Transcriptional landscape illustrates the diversified adaptation of medicinal plants to multifactorial stress combinations linked with high altitude

MAIN CONCLUSION

This study at high-altitude alpine environment reveals the molecular signatures associated with stress response and secondary metabolite accumulation, contributing to Picrorhiza kurroa adaptation, which is primarily regulated by a strong interplay of phytohormones. The high-altitude alpine environment is an extreme and variable environment with unique combinations of abiotic/biotic stresses. Despite progress about plant response to individual and combined abiotic stress in controlled conditions, our knowledge of plant adaptations to multifactorial stress combinations that typically occur in alpine environments is limiting. Here, we utilized the high-altitude medicinal herb Picrorhiza kurroa to investigate how multifactorial stress combinations prevailing along the high-altitude gradient at the western Himalayas affect gene expression and cellular pathways. Leaf transcriptional dynamics identified 7,388 differentially expressed unigenes (DEGs), highlighting unique gene expression patterns, specific pathways, and processes that play a crucial role in plant response to the complex micro-environment of high-altitude. Gene regulatory response largely relies on basic helix-loop-helix (bHLH), no apical meristem (NAC), and ethylene responsive factor (ERF) transcription factor families. Further, unigenes associated with secondary metabolism, multiple abiotic/biotic stress responses, and a variety of cellular and reproductive developmental processes were activated through complex cross-talk among plant hormonal signal transduction pathways. The weak correlation between gene expression and corresponding protein accumulation could predict stress-responsive protein abundance largely under different post-transcriptional/translational regulation. These findings recognize an array of new candidate genes for climate resilience, which would contribute to further our research on high-altitude alpine plant adaptations.

Alpine Adaptive Mechanism on Rhizosphere Microbes Recruitment of Crepis napifera (Franch.) Babc. by Multi-Omics Analysis

Background: The accumulation of secondary metabolites in medicinal plants is often influenced by a variety of factors, and rhizosphere microorganisms typically engage in complex interactions with their host plants. Crepis napifera (Franch.) Babc., a regionally significant medicinal plant, contains a diverse array of terpenoids and demonstrates substantial potential for resource development and utilization. Methods: Transcriptome sequencing, metabolomic profiling, and 16S rRNA gene amplicon sequencing were employed to assess the transcriptional expression patterns, metabolic variations, and rhizosphere microbial community composition of C. napifera (Franch.) Babc. roots distributed across various regions. Results: A total of 3679, 8615, and 11,333 differentially expressed genes (DEGs) were identified in the pairwise comparisons between H1 vs. H2, H2 vs. H3, and H1 vs. H3, respectively. Notably, 497 DEGs were consistently detected across all three comparisons. Additionally, Weighted Gene Co-expression Network Analysis (WGCNA) revealed that the expression levels of genes within the turquoise and yellow modules exhibited a significant positive correlation with elevation. In total, 462 differentially expressed metabolites (DEMs) were identified across the same comparisons. Among these compounds, terpenoids, phenolic acids, amino acids and their derivatives, lipids, and alkaloids accounted for 62.98% of the total differential metabolite content. The accumulation patterns of DEMs varied significantly across different regions in the roots of C. napifera (Franch.) Babc. under the three altitude conditions. In response to environmental conditions and the survival strategy of C. napifera (Franch.) Babc. in alpine areas, an investigation into the rhizosphere microbial community was conducted. Four key microbial genera were identified as being correlated with terpenoid biosynthesis and plant nutritional metabolism. Specifically, Pedosphaera, Acidothermus, and Nevskia exhibited terpene biosynthesis capabilities. Additionally, Herbaspirillum, a common microorganism involved in plant nitrogen fixation, respiration, carbon metabolism, and cell wall metabolism, was also enriched in the rhizosphere of C. napifera (Franch.) Babc. These findings suggested that C. napifera (Franch.) Babc. might recruit these microorganisms to enhance its resistance to environmental stress in alpine areas. Conclusions: The accumulation of terpene in C. napifera (Franch.) Babc. across different regions was influenced by transcriptional changes. The rhizosphere microbial communities also changed during this process, showing a recruitment effect that enhances plant growth and offers potential value.

Boosting Rice Resilience: Role of Biogenic Nanosilica in Reducing Arsenic Toxicity and Defending against Herbivore

The use of nanoparticles is a promising ecofriendly strategy for mitigating both abiotic and biotic stresses. However, the physiological and defense response mechanisms of plants exposed to multiple stresses remain largely unexplored. Herein, we examined how foliar application of biogenic nanosilica (BNS) impacts rice plant growth, molecular defenses, and metabolic responses when subjected to arsenic (As) toxicity and infested by the insect Chilo suppressalis. We show that BNS significantly increased shoot and root silicon accumulation but reduced the shoot As content by 34.7% under herbivory. Additionally, BNS reduced C. suppressalis larval weight gain by 34.5 and 12.3% without and with As stress, respectively. Importantly, BNS enhanced antioxidant enzyme activity under As stress, herbivore attack, and combined pressures, surpassing the effects of traditional silicate fertilizers. BNS ultimately increased rice shoot biomass by 8.2-23.4% under the respective stress conditions compared to the control treatment. Moreover, while As stress alone diminished the plant's resistance to herbivores, BNS application countered this effect by increasing detoxifying compound (e.g., glutathione) production and antioxidant enzyme activity. This study highlights the impact of biotic and abiotic stress interactions on BNS-enhanced plant resilience mechanisms in rice plants, reallocating resources to counter heavy metal toxicity and herbivore damage in agroecosystems.

Adaptation of High-Altitude Plants to Harsh Environments: Application of Phenotypic-Variation-Related Methods and Multi-Omics Techniques

High-altitude plants face extreme environments such as low temperature, low oxygen, low nutrient levels, and strong ultraviolet radiation, causing them to adopt complex adaptation mechanisms. Phenotypic variation is the core manifestation of ecological adaptation and evolution. Many plants have developed a series of adaptive strategies through long-term natural selection and evolution, enabling them to survive and reproduce under such harsh conditions. This article reviews the techniques and methods used in recent years to study the adaptive evolution of high-altitude plants, including transplantation techniques, genomics, transcriptomics, proteomics, and metabolomics techniques, and their applications in high-altitude plant adaptive evolution. Transplantation technology focuses on phenotypic variation, which refers to natural variations in morphological, physiological, and biochemical characteristics, exploring their key roles in nutrient utilization, photosynthesis optimization, and stress-resistance protection. Multiple omics technologies, including genomics, transcriptomics, proteomics, and metabolomics, have revealed genes, regulatory pathways, and metabolic networks associated with phenotypic variations at the genetic and molecular levels. At the same time, the limitations and deficiencies of current technologies used to study plant adaptation to high-altitude environments were discussed. In addition, we propose future improvements to existing technologies and advocate for the integration of different technologies at multiple levels to study the molecular mechanisms of plant adaptation to high-altitude environments, thus providing insights for future research in this field.

Integrated Metabolomic and Transcriptomic Analysis of Nitraria Berries Indicate the Role of Flavonoids in Adaptation to High Altitude

Background: Plants of Nitraria, belonging to the Zygophyllaceae family, are not only widely distributed at an altitude of about 1000 m but also at an altitude of about 3000 m, which is a rare phenomenon. However, little is known about the effect of altitude on the accumulation of metabolites in plants of Nitraria. Furthermore, the mechanism of the high-altitude adaptation of Nitraria has yet to be fully elucidated. Methods: In this study, metabolomics and transcriptomics were used to investigate the differential accumulation of metabolites of Nitraria berries and the regulatory mechanisms in different altitudes. Results: As a result, the biosynthesis of flavonoids is the most significant metabolic pathway in the process of adaptation to high altitude, and 5 Cyanidins, 1 Pelargonidin, 3 Petunidins, 1 Peonidin, and 4 Delphinidins are highly accumulated in high-altitude Nitraria. The results of transcriptomics showed that the structural genes C4H (2), F3H, 4CL (2), DFR (2), UFGT (2), and FLS (2) were highly expressed in high-altitude Nitraria. A network metabolism map of flavonoids was constructed, and the accumulation of differential metabolites and the expression of structural genes were analyzed for correlation. Conclusions: In summary, this study preliminarily offers a new understanding of metabolic differences and regulation mechanisms in plants of Nitraria from different altitudes.

Spatio-Temporal Variations of Volatile Metabolites as an Eco-Physiological Response of a Native Species in the Tropical Forest

This study evaluates the essential oil (EO) composition of Piper rivinoides Kunth, a shrub native to the Brazilian tropical rainforest, across different plant parts and developmental phases. The aim was to explore the chemical diversity of EO and its reflection in the plant's ecological interactions and adaptations. Plant organs (roots, stems, branches, and leaves) at different developmental phases were subjected to hydrodistillation followed by chemical analysis using Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Flame Ionization Detector (GC-FID). The results revealed a relevant variation in EO yield and composition among different plant parts and developmental phases. Leaves showed the highest yield and chemical diversity, with α-pinene and β-pinene as major constituents, while roots and stems were characterized by a predominance of arylpropanoids, particularly apiol. The chemical diversity in leaves increased with plant maturity, indicating a dynamic adaptation to environmental interactions. The study underscores the importance of considering the ontogeny of plant parts in understanding the ecological roles and potential applications of P. rivinoides in medicine and agriculture. The findings contribute to the overall knowledge of Piperaceae chemodiversity and ecological adaptations, offering insights into the plant's interaction with its environment and its potential uses based on chemical composition.

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.

Nutritional quality evaluation and proteome profile of forage species of Western Himalaya

Naturally occurring forage species in the high‐altitude pasturelands of Western Himalaya are traditionally being utilized for feeding of livestock. However, the nutritional quality evaluation and validation of their potential as feed for livestock needs to be undertaken. Here, we evaluated proximate compositions, minerals and amino acids (AAs) of five high‐altitude forage species, namely, Festuca kashmiriana L., Medicago sativa L., Trifolium pratense L., Medicago falcate L. and Melilotus indica L. The results revealed that proximate compositions, mineral and AAs varied significantly among the forage species. The carbohydrate, crude protein, moisture content, crude fat, crude fiber, crude ash, total phenol, oil absorption capacity and water absorption capacity were found in the range of 17.44–37.27 mg/100 mg, 3.34–14.71 mg/100 mg, 88.73%–90.72%, 0.98–2.32 mg/100 mg, 11.16–24.16%, 7.71–34.49%, 292.50–488.12 μg/100 mg, 3.91–4.67 g/g and 2.64–3.41 g/g, respectively. Elemental composition showed that calcium was the predominant element among the minerals (13.91–132.05 mg/kg DM) followed by magnesium (4.60–12.92 mg/kg DM), iron (2.04–76.13 mg/kg DM) and zinc (1.07–2.17 mg/kg DM). Furthermore, we found that these high‐altitude forage species are rich in essential AAs like histidine, tryptophan, valine, leucine, phenylalanine and to some extent isoleucine and tyrosine. In addition, these five species showed distinct proteomes but shared a similar functional group. The proteome profiling of these forage species will help to understand the molecular basis of nutritional enrichment and stress tolerance potential against harsh environmental conditions of high altitudes. Overall, we conclude that traditionally used high‐altitude forage species are nutritionally rich and can be recommended as part of the daily nutritive feed for livestock animals.

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.