Methyl Jasmonate Induced Oxidative Stress and Accumulation of Secondary Metabolites in Plant Cell and Organ Cultures

Methyl jasmonate-loaded composite biofilm sustainably alleviates chilling lignification of loquat fruit during postharvest storage

In this work, the MeJA-loaded gelatin/pullulan/chitosan composite biofilm was prepared to inhibit the chilling lignification of the loquat fruit during storage at 0 °C. The firmness and lignin content were decreased by 89 % and 81.77 % after MeJA-loaded biofilm treatment. Malondialdehyde (MDA) production was almost completely suppressed and chilling injury of loquat fruit was significantly reduced. Enzyme activity results show that the biofilm alleviated chilling lignification mainly by inhibiting peroxidase (POD) activity in the phenylpropanoid pathway (PCCs = 0.715, with lignin content). Also, the conventional MeJA vapor treatment only alleviated lignification on day 3, but the biofilm treatment had a better and more sustained effect throughout the whole storage due to its sustained release ability. Besides, the biofilm had good mechanical properties, transparency and water vapor transmission rate. This work indicates that loading preservatives into biofilms has a promising application prospect for inhibiting the postharvest quality deterioration of fruit and vegetables.

Enhancement of anti-cancer compounds in fungal elicited-Oldenlandia umbellata culture

Our study focused on enhancing the production of anthraquinone derivatives in Oldenlandia umbellata using fungal elicitors. Aspergillus niger, Mucor prayagensis, and Trichoderma viride were used to elicit the anthraquinone derivatives in root cultures. The elicitation process led to an increase in the production of phytochemicals and secondary metabolites, with the highest total protein content observed in A. niger-elicited plants. We performed qualitative and quantitative phytochemical screening of the 80% methanol extract of the plants. Using reverse phase-ultra-fast liquid chromatography, we identified and quantified five anthraquinone compounds: aloe-emodin, rhein, emodin, chrysophanol, and alizarin. The in vitro root samples elicited with A. niger and M. prayagensis exhibited four and three anthraquinone derivatives, respectively, whereas those elicited with T. viride showed only two derivatives. Interestingly, chrysophanol content was the highest in A. niger-elicited root samples. We constructed a system pharmacology framework consisting of 40 nodes and 45 edges with 34 interacting genes. We also identified human proteins that interact with these derivatives, and inferred their roles in cancer-associated pathways. These anthraquinone derivatives interact with various proteins in multiple pathways, including apoptosis, human cytomegalovirus infection, proteoglycans in cancer, MAPK signaling, and hepatitis C, highlighting their potential therapeutic applications in cancer treatment.

A signaling cascade mediating fruit trait development via phosphorylation-modulated nuclear accumulation of JAZ repressor

It is generally accepted that jasmonate-ZIM domain (JAZ) repressors act to mediate jasmonate (JA) signaling via CORONATINE-INSENSITIVE1 (COI1)-mediated degradation. Here, we report a cryptic signaling cascade where a JAZ repressor, FvJAZ12, mediates multiple signaling inputs via phosphorylation-modulated subcellular translocation rather than the COI1-mediated degradation mechanism in strawberry (Fragaria vesca). FvJAZ12 acts to regulate flavor metabolism and defense response, and was found to be the target of FvMPK6, a mitogen-activated protein kinase that is capable of responding to multiple signal stimuli. FvMPK6 phosphorylates FvJAZ12 at the amino acid residues S179 and T183 adjacent to the PY residues, thereby attenuating its nuclear accumulation and relieving its repression for FvMYC2, which acts to control the expression of lipoxygenase 3 (FvLOX3), an important gene involved in JA biosynthesis and a diverse array of cellular metabolisms. Our data reveal a previously unreported mechanism for JA signaling and decipher a signaling cascade that links multiple signaling inputs with fruit trait development.

Modulation of Tropane Alkaloids' Biosynthesis and Gene Expression by Methyl Jasmonate in Datura stramonium L.: A Comparative Analysis of Scopolamine, Atropine, and Hyoscyamine Accumulation

Scopolamine and atropine are two medicinal alkaloids derived from Datura stramonium L. with anticholinergic properties. This study explored how methyl jasmonate (MJ), a plant growth regulator, affects the biosynthesis and accumulation of these alkaloids in different plant tissues. The expression levels of putrescine N-methyltransferase (PMT), tropinone reductase I (TR1), and hyoscyamine 6β-hydroxylase (h6h), three critical enzymes in the biosynthetic pathway, were also analyzed. The results indicated that MJ at 150 µM increased the production of scopolamine and atropine in both leaves and roots, while MJ at 300 µM had an adverse effect. Furthermore, MJ enhanced the expression of PMT, TR1, and h6h genes in the roots, the primary site of alkaloid synthesis, but not in the leaves, the primary site of alkaloid storage. These results imply that MJ can be applied to regulate the biosynthesis and accumulation of scopolamine and atropine in D. stramonium, thereby improving their production efficiency.

Methyl-Jasmonate Functions as a Molecular Switch Promoting Cross-Talk between Pathways for the Biosynthesis of Isoprenoid Backbones Used to Modify Proteins in Plants

In plants, the plastidial mevalonate (MVA)-independent pathway is required for the modification with geranylgeranyl groups of CaaL-motif proteins, which are substrates of protein geranylgeranyltransferase type-I (PGGT-I). As a consequence, fosmidomycin, a specific inhibitor of 1-deoxy-d-xylulose (DX)-5 phosphate reductoisomerase/DXR, the second enzyme in this so-called methylerythritol phosphate (MEP) pathway, also acts as an effective inhibitor of protein prenylation. This can be visualized in plant cells by confocal microscopy by expressing GFP-CaM-CVIL, a prenylation sensor protein. After treatment with fosmidomycin, the plasma membrane localization of this GFP-based sensor is altered, and a nuclear distribution of fluorescence is observed instead. In tobacco cells, a visual screen of conditions allowing membrane localization in the presence of fosmidomycin identified jasmonic acid methyl esther (MeJA) as a chemical capable of gradually overcoming inhibition. Using Arabidopsis protein prenyltransferase loss-of-function mutant lines expressing GFP-CaM-CVIL proteins, we demonstrated that in the presence of MeJA, protein farnesyltransferase (PFT) can modify the GFP-CaM-CVIL sensor, a substrate the enzyme does not recognize under standard conditions. Similar to MeJA, farnesol and MVA also alter the protein substrate specificity of PFT, whereas DX and geranylgeraniol have limited or no effect. Our data suggest that MeJA adjusts the protein substrate specificity of PFT by promoting a metabolic cross-talk directing the origin of the prenyl group used to modify the protein. MVA, or an MVA-derived metabolite, appears to be a key metabolic intermediate for this change in substrate specificity.

Influence of Abiotic and Biotic Elicitors on Organogenesis, Biomass Accumulation, and Production of Key Secondary Metabolites in Asteraceae Plants

The medicinal plants of the Asteraceae family are a valuable source of bioactive secondary metabolites, including polyphenols, phenolic acids, flavonoids, acetylenes, sesquiterpene lactones, triterpenes, etc. Under stressful conditions, the plants develop these secondary substances to carry out physiological tasks in plant cells. Secondary Asteraceae metabolites that are of the greatest interest to consumers are artemisinin (an anti-malarial drug from Artemisia annua L.-sweet wormwood), steviol glycosides (an intense sweetener from Stevia rebaudiana Bert.-stevia), caffeic acid derivatives (with a broad spectrum of biological activities synthesized from Echinacea purpurea (L.) Moench-echinacea and Cichorium intybus L.-chicory), helenalin and dihydrohelenalin (anti-inflammatory drug from Arnica montana L.-mountain arnica), parthenolide ("medieval aspirin" from Tanacetum parthenium (L.) Sch.Bip.-feverfew), and silymarin (liver-protective medicine from Silybum marianum (L.) Gaertn.-milk thistle). The necessity to enhance secondary metabolite synthesis has arisen due to the widespread use of these metabolites in numerous industrial sectors. Elicitation is an effective strategy to enhance the production of secondary metabolites in in vitro cultures. Suitable technological platforms for the production of phytochemicals are cell suspension, shoots, and hairy root cultures. Numerous reports describe an enhanced accumulation of desired metabolites after the application of various abiotic and biotic elicitors. Elicitors induce transcriptional changes in biosynthetic genes, leading to the metabolic reprogramming of secondary metabolism and clarifying the mechanism of the synthesis of bioactive compounds. This review summarizes biotechnological investigations concerning the biosynthesis of medicinally essential metabolites in plants of the Asteraceae family after various elicitor treatments.

Impact of Heavy Metal Pollution in the Environment on the Metabolic Profile of Medicinal Plants and Their Therapeutic Potential

The paper provides a comprehensive examination of heavy metal stress on medicinal plants, focusing on its impact on antioxidant capacity and biosynthetic pathways critical to their therapeutic potential. It explores the complex relationship between heavy metals and the physiological and biochemical responses of medicinal plants, highlighting how metal stress disrupts biosynthetic pathways, altering concentrations of secondary metabolites. This disruption may compromise the overall quality and efficacy of medicinal plants, requiring a holistic understanding of its cumulative impacts. Furthermore, the study discusses the potential of targeted genetic editing to enhance plant resilience against heavy metal stress by manipulating genes associated with antioxidant defenses. This approach represents a promising frontier in safeguarding medicinal plants in metal-contaminated environments. Additionally, the research investigates the role of phytohormone signaling in plant adaptive mechanisms to heavy metal stress, revealing its influence on biochemical and physiological responses, thereby adding complexity to plant adaptation. The study underscores the importance of innovative technologies and global cooperation in protecting medicinal plants' therapeutic potential and highlights the need for mitigation strategies to address heavy metal contamination effectively.

Examining preharvest genetic and morphological factors contributing to lettuce (Lactuca sativa L.) shelf-life

Lettuce is a highly perishable horticultural crop with a relatively short shelf-life that limits its commercial value and contributes to food waste. Postharvest senescence varies with influences of both environmental and genetic factors. From a larger pool of romaine lettuce genotypes, we identified three genotypes with variable shelf lives and evaluated their leaf morphology characteristics and transcriptomic profiles at preharvest to predict postharvest quality. Breeding line 60184 had the shortest shelf-life (SSL), cultivar 'Manatee' had an intermediate shelf-life (ISL), and 'Okeechobee' had the longest shelf-life (LSL). We observed significantly larger leaf lamina thickness and higher stomatal index in the SSL genotypes relative to the LSL cultivar. To identify molecular indicators of shelf-life, we used a transcriptional approach between two of the contrasting genotypes, breeding line 60184 and cultivar 'Okeechobee' at preharvest. We identified 552 upregulated and 315 downregulated differentially expressed genes between the genotypes, from which 27% of them had an Arabidopsis thaliana ortholog previously characterized as senescence associated genes (SAGs). Notably, we identified several SAGs including several related to jasmonate ZIM-domain jasmonic acid signaling, chlorophyll a-b binding, and cell wall modification including pectate lyases and expansins. This study presented an innovative approach for identifying preharvest molecular factors linked to postharvest traits for prolonged shelf.

The effects of green and chemically-synthesized copper oxide nanoparticles on the production and gene expression of morphinan alkaloids in Oriental poppy

Oriental poppy (Papaver orientale L.) belonging to the Papaveraceae family, has the capacity to synthesize a wide range of benzylisoquinoline alkaloids (BIAs). This experiment was conducted to investigate the effects of green and chemical copper oxide nanoparticles (CuO NPs) elicitors on oxidative stress and the BIAs biosynthesis pathway in the cell suspension culture of P. orientale. This research shows that both green and chemical CuO NPs at concentrations of 20 mg/L and 40 mg/L, induce oxidative stress in the cell suspension of P. orientale by increasing the production of H2O2 and the activity of antioxidant enzymes. The comparison of treatments revealed that utilizing a lower concentration of CuO NPs (20 mg/L) and extending the duration of cell suspension incubation (up to 48 h) play a more influential role in inducing the expression of the BIAs biosynthesis pathway genes (PsWRKY, TYDC, SalSyn, SalR, SalAT, T6ODM, COR and CODM) and increasing the production of morphinan alkaloids (thebaine, codeine, and morphine). The overarching results indicate that the concentration of CuO NPs and the duration of cell treatment have a more significant impact than the nature of CuO NPs in inducing oxidative stress and stimulating the expression of the BIAs pathway genes.

Methyl jasmonate conferred Arsenic tolerance in Thymus kotschyanus by DNA hypomethylation, stimulating terpenoid metabolism, and upregulating two cytochrome P450 monooxygenases

Arsenic (As) is a highly cytotoxic element impairing normal cellular functions, and its bioremediation has become one of the environmental concerns. This study explored the molecular and physiological responses of thyme (Thymus kotschyanus) seedlings to incorporating As (0 and 10 mgl-1) and methyl jasmonate (MJ; 0 and 10 µM) into the culture medium. The MJ treatment reinforced root system and mitigated the As cytotoxicity risk. MJ contributed to hypomethylation, a potential adaptation mechanism for conferring the As tolerance. Two cytochrome P450 monooxygenases, including CYP71D178 and CYP71D180 genes, were upregulated in response to As and MJ. The MJ treatment contributed to up-regulation in the γ-terpinene synthase (TPS) gene, a marker gene in the terpenoid metabolism. The As presence reduced photosynthetic pigments (chlorophylls and carotenoids), while the MJ utilization alleviated the As toxicity. The MJ supplementation increased proline accumulation and soluble phenols. The application of MJ declined the toxicity sign of As on the concentration of proteins. The activities of peroxidase, catalase, and phenylalanine ammonia-lyase (PAL) enzymes displayed an upward trend in response to As and MJ treatments. Taken collective, MJ can confer the As tolerance by triggering DNA hypomethylation, regulating CYPs, and stimulating primary and secondary metabolism, especially terpenoid.

Enhanced production of withaferin A from the hairy root culture of Withania somnifera via synergistic effect of Methyl jasmonate and β-cyclodextrin

Due to low amounts of withanolides produced in some plants and high demand for various applications, their biotechnological production is widely researched. The effects of two explant types (i.e., leaf and stem from the in vitro seedlings of three genotypes of Withania somnifera) and four Rhizobium strains (i.e., LBA 9402, A4, ATCC 15834, and C58C1) to improve hairy root formation efficiency was studied. Furthermore, the combined effects of β-cyclodextrin (β-CD) and methyl jasmonate (MeJA) on withaferin A production after 48 h exposure time was examined. Four hairy roots having the maximum percentage of induced roots and mean number of induced roots to analyze their growth kinetics and identified G3/ATCC/LEAF culture having the maximum specific growth rate (μ = 0.036 day-1) and growth index (GI = 9.18), and the shortest doubling time (Td = 18.82 day) were selected. After 48 h exposure of G3/ATCC/LEAF culture to different elicitation conditions, maximum amounts of withaferin A were produced in samples co-treated with 0.5 mM β-CD + 100 μM MeJA (9.57 mg/g DW) and 5.0 mM β-CD + 100 μM MeJA (17.45 mg/g DW). These outcomes represented a 6.8-fold and 12.5-fold increase, respectively, compared to the control. Similarly, combined β-CD/MeJA elicitation increased gene expression levels of HMGR, SQS, SMT-1, and SDS/CYP710A involved in withanolides biosynthetic pathway, of which just SMT-1 had significant correlation with withaferin A production. These results demonstrated the superiority of G1-leaf explant and ATCC 15834 for hairy root induction, and revealed synergistic effect of MeJA and β-CD on withaferin A production.

Integrative multi-omics analysis reveals the crucial biological pathways involved in the adaptive response to NaCl stress in peanut seedlings

Plant growth is restricted by salt stress, which is a significant abiotic factor, particularly during the seedling stage. The aim of this study was to investigate the mechanisms underlying peanut adaptation to salt stress by transcriptomic and metabolomic analysis during the seedling stage. In this study, phenotypic variations of FH23 and NH5, two peanut varieties with contrasting tolerance to salt, changed obviously, with the strongest differences observed at 24 h. FH23 leaves wilted and the membrane system was seriously damaged. A total of 1470 metabolites were identified, with flavonoids being the most common (21.22%). Multi-omics analyses demonstrated that flavonoid biosynthesis (ko00941), isoflavones biosynthesis (ko00943), and plant hormone signal transduction (ko04075) were key metabolic pathways. The comparison of metabolites in isoflavone biosynthesis pathways of peanut varieties with different salt tolerant levels demonstrated that the accumulation of naringenin and formononetin may be the key metabolite leading to their different tolerance. Using our transcriptomic data, we identified three possible reasons for the difference in salt tolerance between the two varieties: (1) differential expression of LOC112715558 (HIDH) and LOC112709716 (HCT), (2) differential expression of LOC112719763 (PYR/PYL) and LOC112764051 (ABF) in the abscisic acid (ABA) signal transduction pathway, then (3) differential expression of genes encoding JAZ proteins (LOC112696383 and LOC112790545). Key metabolites and candidate genes related to improving the salt tolerance in peanuts were screened to promote the study of the responses of peanuts to NaCl stress and guide their genetic improvement.

Methyl jasmonate improves resistance in scab-susceptible Red Delicious apple by altering ROS homeostasis and enhancing phenylpropanoid biosynthesis

Apple (Malus domestica) is an economically important rosaceous fruit crop grown at temperate climate zones. Nevertheless, its production is severely affected by scab disease caused by the ascomycetous fungus Venturia inaequalis (VI). Methyl jasmonate (MeJA) is a stress induced plant hormone, shown to induce resistance against wide range of pathogens. The current study investigated the role of MeJA in promoting scab tolerance in susceptible apple varieties through exogenous application of optimized (100 μM) MeJA concentration, followed by VI infection. According to our analysis, applying MeJA exogenously onto leaf surfaces resulted in increased membrane stability and decreased malondialdehyde levels in Red Delicious, suggesting that MeJA is capable of protecting tissues against oxidative damage through its role in restoring membrane stability. In addition, the changes in the levels of key antioxidative enzymes and reactive oxygen species (ROS) showed that exogenous MeJA maintains ROS homeostasis as well. Higher phenylalanine ammonia-lyase activity and increased accumulation of phenylpropanoids in MeJA-treated VI-infected plants indicated the MeJA reprogrammed phenylpropanoid biosynthesis pathway for scab tolerance. Our study of scab tolerance in apples induced by MeJA provides new insights into its physiological and biochemical mechanisms.

Defense Responses of Different Rice Varieties Affect Growth Performance and Food Utilization of Cnaphalocrocis medinalis Larvae

Rice leaf folder, Cnaphalocrocis medinalis (Guenée), is one of the most serious pests on rice. At present, chemical control is the main method for controlling this pest. However, the indiscriminate use of chemical insecticides has non-target effects and may cause environmental pollution. Besides, leaf curling behavior by C. medinalis may indirectly reduce the efficacy of chemical spray. Therefore, it is crucial to cultivate efficient rice varieties resistant to this pest. Previous studies have found that three different rice varieties, Zhongzao39 (ZZ39), Xiushui134 (XS134), and Yongyou1540 (YY1540), had varying degrees of infestation by C. medinalis. However, it is currently unclear whether the reason for this difference is related to the difference in defense ability of the three rice varieties against the infestation of C. medinalis. To explore this issue, the current study investigated the effects of three rice varieties on the growth performance and food utilization capability of the 4th instar C. medinalis. Further, it elucidated the differences in defense responses among different rice varieties based on the differences in leaf physiological and biochemical indicators and their impact on population occurrence. The results showed that the larval survival rate was the lowest, and the development period was significantly prolonged after feeding on YY1540. This was not related to the differences in leaf wax, pigments, and nutritional components among the three rice varieties nor to the feeding preferences of the larvae. The rate of superoxide anion production, hydrogen peroxide content, and the activity of three protective enzymes were negatively correlated with larval survival rate, and they all showed the highest in YY1540 leaves. Compared to other tested varieties, although the larvae feeding on YY1540 had higher conversion efficiency of ingested food and lower relative consumption rate, their relative growth was faster, indicating stronger food utilization capability. However, they had a lower accumulation of protein. This suggests that different rice varieties had different levels of oxidative stress after infestation by C. medinalis. The defense response of YY1540 was more intense, which was not conducive to the development of the larvae population. These results will provide new insights into the interaction mechanism between different rice varieties and C. medinalis and provide a theoretical basis for cultivating rice varieties resistant to this pest.

Exogenous methyl jasmonate affects genes involved in monoterpene biosynthetic pathway, phyto-biochemical accumulation, and enzymatic activity of Satureja hortensis L

Satureja hortensis L. (SH) is a medicinal and aromatic herb utilized markedly in the food, pharmaceutical, and cosmetic industries because of its specific secondary metabolites (SMs), especially monoterpenoids. However, the impact of elicitors on the expression of monoterpene synthase genes in SH remains unexplored. Therefore, the supreme objective of this research was to elucidate the phyto-biochemical and targeted genes expression responses of SH to the exogenous application of methyl jasmonate (MeJA). Accordingly, having chosen four concentrations of MeJA, they sprayed at the five-leaf stage for two weeks, and then leaves were harvested at two exposure times of 24 and 48 hrs for further analysis, using spectrophotometric, real time-quantitative polymerase chain reaction (RT-qPCR), and gas chromatography-mass spectrometric (GC-MS) methods. The results highlight that not only were the highest contents of phenolic, flavonoids, peroxidase, superoxide dismutase, proline, and malondialdehyde in the elicited SHs but also the highest expression of β-farnesene synthase (BFS) and 1-deoxy-D-xylulose 5-phosphate reductase (DXR) genes together with the highest amount of carvacrol were up-regulated in them compared to their respective control. In conclusion, these findings demonstrate the great industrial potential of MeJA in improving the production of phytochemicals in medicinal plants, particularly in SH.

Integrative effects of phytohormones in the phenolic acids production in Salvia verticillata L. under multi-walled carbon nanotubes and methyl jasmonate elicitation

Salvia verticillata L. is a well-known herb rich in rosmarinic acid (RA) and with therapeutic values. To better understand the possible roles of phytohormones in the production of phenolic acids in S. verticillata, in this work, we investigated some physiological and biochemical responses of the species to methyl jasmonate (MJ) and multi-walled carbon nanotubes (MWCNTs) as two effective elicitors. The leaves were sprayed with aqueous solutions containing 100 mg L-1 MWCNTs and 100 µM MJ and then harvested during interval times of exposure up to 96 h. The level of abscisic acid, as the first effective phytohormone, was altered in the leaves in response to MJ and MWCNTs elicitation (2.26- and 3.06-fold more than the control, respectively), followed by significant increases (P ˂ 0.05) detected in jasmonic acid and salicylic acid contents up to 8 h after exposure. Obtained data revealed that simultaneously with changes in phytohormone profiles, significant (P ˂ 0.05) rises were observed in the content of H2O2 (8.85- and 9.74-folds of control), and the amount of lipid peroxidation (10.18- and 17.01-folds of control) during the initial times after exposure to MJ and MWCNTs, respectively. Later, the content of phenolic acids increased in the elicited leaves due to changes in the transcription levels of key enzymes involved in their biosynthesis pathways, so 2.71- and 11.52-fold enhances observed in the RA content of the leaves after exposure to MJ and MWCNTs, respectively. It is reasonable to conclude that putative linkages between changes in some phytohormone pools lead to the accumulation of phenolic acids in the leaves of S. verticillata under elicitation. Overall, the current findings help us improve our understanding of the signal transduction pathways of the applied stimuli that led to enhanced secondary metabolite production in medicinal plants.

Metabolomics Reveals Rubiadin Accumulation and the Effects of Methyl Jasmonate Elicitation in Damnacanthus major Calli

Callus suspension techniques have been considered attractive for improving bioactive metabolite productivity; methyl jasmonate (MeJA) is a widely used elicitor for stimulating synthetic pathways. In this study, a multivariate analysis-based metabolomics approach was employed to investigate the primary and specialized metabolites in the leaves, unelicited calli, and 100 or 200 μM MeJA elicited calli of Damnacanthus major. Rubiadin, a powerful anthraquinone with various therapeutic properties, was only identified in D. major calli, accumulating in a MeJA elicitation concentration-dependent manner. Callus cultures also contained high levels of amino acids, sugars, and phenolic compounds, indicating energy metabolism and metabolic adaptation responses for proliferation and stabilization. Regarding MeJA application, elicited calli contained higher amounts of quinic acid, kaempferol, and glucose with lower amounts of sucrose and raffinose than those in the unelicited control, which were closely related to protective mechanisms against MeJA. Moreover, excessive elicitation increased the asparagine, fructose, and raffinose levels and decreased the glucose and sucrose levels, which was ascribed to increased activation of the aminoacyl-tRNA biosynthesis pathway and wider utilization of glucose than of fructose after sucrose degradation. These results will be useful for optimizing plant cell culture techniques to achieve high production rates for valuable specialized metabolites.

β-glucan-induced disease resistance in plants: A review

Systemic acquired resistance (SAR) and induced systemic resistance (ISR) are caused by various factors, including both pathogenic and non-pathogenic ones. β-glucan primarily originates from bacteria and fungi, some species of these organisms work as biological agents in causing diseases. When β-glucan enters plants, it triggers the defense system, leading to various reactions such as the production of proteins related to pathogenicity and defense enzymes. By extracting β-glucan from disturbed microorganisms and using it as an inducing agent, plant diseases can be effectively controlled by activating the plant's defense system. β-glucan plays a crucial role during the interaction between plants and pathogens. Therefore, modeling the plant-pathogen relationship and using the molecules involved in this interaction can help in controlling plant diseases, as pathogens have genes related to resistance against pathogenicity. Thus, it is reasonable to identify and use biological induction agents at a large scale by extracting these compounds.

Identification of Potential Factors for the Promotion of Fucoxanthin Synthesis by Methyl Jasmonic Acid Treatment of Phaeodactylum tricornutum

Fucoxanthin, a vital secondary metabolite produced by marine diatoms, has great economic value and research potential. However, its popularization and application have been greatly restricted due to its low content, difficult extraction, and high production cost. Methyl jasmonic acid (MeJA) exerts similar inductive hormones in the growth and development as well as metabolic processes of plants. In Phaeodactylum tricornutum (P. tricornutum), MeJA treatment can increase fucoxanthin content. In this study, the effects of different concentrations of MeJA on the cell growth and the fucoxanthin content of P. tricornutum were explored. Meanwhile, this study used high-throughput sequencing technology for transcriptome sequencing of P. tricornutum and subsequently performed differential gene expression analysis, gene ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and weighted gene co-expression network analysis (WGCNA) for screening the hub genes for the promotion of fucoxanthin synthesis with MeJA-treated P. tricornutum. On this basis, the functions of the hub genes for the promotion of fucoxanthin synthesis with MeJA-treated P. tricornutum were further analyzed. The results revealed that the carotenoid synthesis-related genes PHATRDRAFT_54800 and PHATRDRAFT_20677 were the hub genes for the promotion of fucoxanthin synthesis with MeJA-treated P. tricornutum. PHATRDRAFT_54800 may be a carotenoid isomerase, while PHATRDRAFT_20677 may be involved in the MeJA-stimulated synthesis of fucoxanthin by exerting the role of SDR family NAD(P)-dependent oxidoreductases.

The advent of plant cells in bioreactors

Ever since agriculture started, plants have been bred to obtain better yields, better fruits, or sustainable products under uncertain biotic and abiotic conditions. However, a new way to obtain products from plant cells emerged with the development of recombinant DNA technologies. This led to the possibility of producing exogenous molecules in plants. Furthermore, plant chemodiversity has been the main source of pharmacological molecules, opening a field of plant biotechnology directed to produce high quality plant metabolites. The need for different products by the pharma, cosmetics agriculture and food industry has pushed again to develop new procedures. These include cell production in bioreactors. While plant tissue and cell culture are an established technology, beginning over a hundred years ago, plant cell cultures have shown little impact in biotechnology projects, compared to bacterial, yeasts or animal cells. In this review we address the different types of bioreactors that are currently used for plant cell production and their usage for quality biomolecule production. We make an overview of Nicotiana tabacum, Nicotiana benthamiana, Oryza sativa, Daucus carota, Vitis vinifera and Physcomitrium patens as well-established models for plant cell culture, and some species used to obtain important metabolites, with an insight into the type of bioreactor and production protocols.

Comparative Analysis of Organic Extracts Bioactivity from Two Limonium. Mill Species Growing Wild in Tunisian Salty Marshes

Limonium. Mill is a genus of flowering plants belonging to the Plumbaginaceae family. The present study aimed to compare two Limonium species (L. pruinosum Kuntze and L. tunetanum (Barratte & Bonnet) Maire) in terms of their chemical composition and bioactivity. Chemical profiling showed that the methanolic (MeOH) extracts of both species were the most enriched with total phenolic (TP) and total flavonoid (TF) contents. The TFC were higher in L. tunetanum compared to L. pruinosum. HPLC-DAD analysis showed that distinctly the gallic acid and L-tyrosine 7-amido-4-methylcoumarin were the main compounds for L. pruinosum and L. tunetanum, respectively. For both Limonium. Mil species, the MeOH extracts displayed the highest antioxidant with IC50 of 7.7 and 8.4 μg/mL for L. pruinosum and L. tunetanum, respectively. The highest anti-15-lipoxygnase activity was recorded in the ethyl acetate (IC50 =14.2 μg/mL) and Methanol (IC50 =15.6 μg/mL) extracts for L. pruinosum. However, for L. tunetanum the best activity was recorded for dichloromethane extract (IC50 =10.4 μg/mL). L. pruinosum extracts displayed the highest cytotoxic activity against MCF-7 and HCT-116 cell lines compared to L. tunetanum ones. The obtained bioactivity discrepancy between Limonium. Mill species was discussed in relation to the organic extract chemical richness.

Metabolomic analyses provide insights into the preharvest rind disorder in Satsuma Owari Mandarin

Citrus fruit's appearance is the primary criterion used to assess its quality for the fresh market, hence the rind's condition is a crucial quality trait. Pre-harvest rind disorder is one of the major physiological problems in mandarins. The disorder occurs right before harvest following rain events in some Mandarin varieties. Despite the economic damage caused by this kind of disorder, very limited information is available about the molecular mechanisms underlying the occurrence of this disorder. In the present study, we evaluated the primary metabolites, antioxidants, and hormones associated with the pre-harvest rind disorder in Mandarins. The study was carried out using ten-year-old 'Owari' Satsuma mandarin trees grafted on 'Carrizo' rootstock and grown in a commercial orchard in San Joaquin Valley, California, USA. Samples were collected from healthy tissue of healthy fruit (HF_HT), healthy tissue of damaged fruit (DF_HT), and damaged tissue of damaged fruit (DF_DT). Damaged fruit (DF_HT and DF_DT) showed lower cellulose concentrations than healthy fruit tissues (HF_HT), however, had similar contents of pectin and hemicellulose. The antioxidant activities showed no significant difference in all paired comparisons between samples as expressed in the malondialdehyde (MDA) content. However, DF_DT had a higher H2O2 content compared to HF_HT, but DF_HT had a similar content to that of HF_HT. Furthermore, peroxidase (POD) and polyphenol oxidase (PPO) activities were increased in DF_DT compared to HF_HT (P = 0.0294) and DF_HT (P = 0.0044), respectively. Targeted metabolomics analysis revealed that a total of 76 metabolites were identified in Satsuma rind tissues, and the relative concentrations of 43 metabolites were significantly different across studied samples. The hormonal analysis showed the involvement of jasmonate O-methyltransferase, jasmonic acid-amido synthetase JAR1-like, and JA-isoleucine may key role in causing the rind disorder in mandarins. In addition, the damaged fruit tissues have a higher level of jasmonic acid (JA), 12-oxo-phytodienoic acid, and JA-isoleucine than undamaged tissue.

Biosynthesis of Betalains Elicited by Methyl Jasmonate in Two Species of Alternanthera Genus: Antagonistic Regulations Result in Increase of Pigments

Natural pigments are components very important in the dye industry. The betalains are pigments found in plants from Caryophyllales order and are relevant in the food manufacturing. The main source of betalains is beetroot, which has unfavorable aftertaste. Therefore, the demand for alternative species producing betalains has increased. Elicitor molecules such as methyl jasmonate (MeJA) induce metabolic reprogramming acting in the biosynthesis of specialized metabolites and can enhance pigment concentrations. Here, we used this strategy to identify if treatment with MeJA at 100 µM can promote the accumulation of betalains and other bioactive compounds in Alternanthera philoxeroides and Alternanthera sessilis. We performed the gene expression, concentration of betalains, phenols, flavonoids, amino acids (phenylalanine and tyrosine), and antioxidant activity. The results showed that MeJA treatment increased betalains and other bioactive compounds in the two Alternanthera species but A. sessilis had a better performance. One key factor in this pathway is related to the phenylalanine and tyrosine concentration. However, the species have distinct metabolic regulation: in A. philoxeroides, high concentrations of betalain pigments increase the tyrosine concentration and gene expression (include ADH) under MeJA and in A. sessilis, high concentrations of betalain pigments reduce the gene expression and tyrosine concentration after 2 days under MeJA. This study brings new questions about betalain biosynthesis and sheds light on the evolution of this pathway in Caryophyllales.

Suspension culture of somatic embryos for the production of high-value secondary metabolites

Secondary metabolites from plants are ubiquitous and have applications in medicines, food additives, scents, colorants, and natural pesticides. Biotechnological production of secondary metabolites that have economic benefits is an attractive alternative to conventional methods. Cell, adventitious, and hairy root suspension cultures are typically used to produce secondary metabolites. According to recent studies, somatic embryos in suspension culture are useful tools for the generation of secondary metabolites. Somatic embryogenesis is a mode of regeneration in several plant species. This review provides an update on the use of somatic embryogenesis in the production of valuable secondary metabolites. The factors influencing the generation of secondary metabolites using somatic embryos in suspension cultures, elicitation methods, and prospective applications are also discussed in this review.

Graphical abstract

Exploring the Interplay between Metabolic Pathways and Taxane Production in Elicited Taxus baccata Cell Suspensions

Taxus cell cultures are a reliable biotechnological source of the anticancer drug paclitaxel. However, the interplay between taxane production and other metabolic pathways during elicitation remains poorly understood. In this study, we combined untargeted metabolomics and elicited Taxus baccata cell cultures to investigate variations in taxane-associated metabolism under the influence of 1 µM coronatine (COR) and 150 µM salicylic acid (SA). Our results demonstrated pleiotropic effects induced by both COR and SA elicitors, leading to differential changes in cell growth, taxane content, and secondary metabolism. Metabolite annotation revealed significant effects on N-containing compounds, phenylpropanoids, and terpenoids. Multivariate analysis showed that the metabolomic profiles of control and COR-treated samples are closer to each other than to SA-elicited samples at different time points (8, 16, and 24 days). The highest level of paclitaxel content was detected on day 8 under SA elicitation, exhibiting a negative correlation with the biomarkers kauralexin A2 and taxusin. Our study provides valuable insights into the intricate metabolic changes associated with paclitaxel production, aiding its potential optimization through untargeted metabolomics and an evaluation of COR/SA elicitor effects.

Signal Mediators in the Implementation of Jasmonic Acid's Protective Effect on Plants under Abiotic Stresses

Plant cells respond to stress by activating signaling and regulatory networks that include plant hormones and numerous mediators of non-hormonal nature. These include the universal intracellular messenger calcium, reactive oxygen species (ROS), gasotransmitters, small gaseous molecules synthesized by living organisms, and signal functions such as nitrogen monoxide (NO), hydrogen sulfide (H₂S), carbon monoxide (CO), and others. This review focuses on the role of functional linkages of jasmonic acid and jasmonate signaling components with gasotransmitters and other signaling mediators, as well as some stress metabolites, in the regulation of plant adaptive responses to abiotic stressors. Data on the involvement of NO, H₂S, and CO in the regulation of jasmonic acid formation in plant cells and its signal transduction were analyzed. The possible involvement of the protein components of jasmonate signaling in stress-protective gasotransmitter effects is discussed. Emphasis is placed on the significance of the functional interaction between jasmonic acid and signaling mediators in the regulation of the antioxidant system, stomatal apparatus, and other processes important for plant adaptation to abiotic stresses.

Effects of LPS from Rhodobacter sphaeroides, a Purple Non-Sulfur Bacterium (PNSB), on the Gene Expression of Rice Root

The effects of lipopolysaccharide (LPS) from Rhodobacter sphaeroides, a purple non-sulfur bacterium (PNSB), on the gene expression of the root of rice (Oryza sativa) were investigated by next generation sequencing (NGS) RNA-seq analysis. The rice seeds were germinated on agar plates containing 10 pg/mL of LPS from Rhodobacter sphaeroides NBRC 12203 (type culture). Three days after germination, RNA samples were extracted from the roots and analyzed by RNA-seq. The effects of dead (killed) PNSB cells of R. sphaeroides NBRC 12203^T at the concentration of 10¹ cfu/mL (ca. 50 pg cell dry weight/mL) were also examined. Clean reads of NGS were mapped to rice genome (number of transcript ID: 44785), and differentially expressed genes were analyzed by DEGs. As a result of DEG analysis, 300 and 128 genes, and 86 and 8 genes were significantly up- and down-regulated by LPS and dead cells of PNSB, respectively. The plot of logFC (fold change) values of the up-regulated genes of LPS and PNSB dead cells showed a significant positive relationship (r² = 0.6333, p < 0.0001), indicating that most of the effects of dead cell were attributed to those of LPS. Many genes related to tolerance against biotic (fungal and bacterial pathogens) and abiotic (cold, drought, and high salinity) stresses were up-regulated, and the most strikingly up-regulated genes were those involved in the jasmonate signaling pathway, and the genes of chalcone synthase isozymes, indicating that PNSB induced defense response against biotic and abiotic stresses via the jasmonate signaling pathway, despite the non-pathogenicity of PNSB.

The Influence of Lead and Acyrthosiphon pisum (Harris) on Generation of Pisum sativum Defense Signaling Molecules and Expression of Genes Involved in Their Biosynthesis

The main aim of this study was to understand the regulation of the biosynthesis of phytohormones as signaling molecules in the defense mechanisms of pea seedlings during the application of abiotic and biotic stress factors. It was important to identify this regulation at the molecular level in Pisum sativum L. seedlings under the influence of various concentrations of lead-i.e., a low concentration increasing plant metabolism, causing a hormetic effect, and a high dose causing a sublethal effect-and during feeding of a phytophagous insect with a piercing-sucking mouthpart-i.e., pea aphid (Acyrthosiphon pisum (Harris)). The aim of the study was to determine the expression level of genes encoding enzymes of the biosynthesis of signaling molecules such as phytohormones-i.e., jasmonates (JA/MeJA), ethylene (ET) and abscisic acid (ABA). Real-time qPCR was applied to analyze the expression of genes encoding enzymes involved in the regulation of the biosynthesis of JA/MeJA (lipoxygenase 1 (LOX1), lipoxygenase 2 (LOX2), 12-oxophytodienoate reductase 1 (OPR1) and jasmonic acid-amido synthetase (JAR1)), ET (1-aminocyclopropane-1-carboxylate synthase 3 (ACS3)) and ABA (9-cis-epoxycarotenoid dioxygenase (NCED) and aldehyde oxidase 1 (AO1)). In response to the abovementioned stress factors-i.e., abiotic and biotic stressors acting independently or simultaneously-the expression of the LOX1, LOX2, OPR1, JAR1, ACS3, NCED and AO1 genes at both sublethal and hormetic doses increased. Particularly high levels of the relative expression of the tested genes in pea seedlings growing at sublethal doses of lead and colonized by A. pisum compared to the control were noticeable. A hormetic dose of lead induced high expression levels of the JAR1, OPR1 and ACS3 genes, especially in leaves. Moreover, an increase in the concentration of phytohormones such as jasmonates (JA and MeJA) and aminococyclopropane-1-carboxylic acid (ACC)-ethylene (ET) precursor was observed. The results of this study indicate that the response of pea seedlings to lead and A. pisum aphid infestation differed greatly at both the gene expression and metabolic levels. The intensity of these defense responses depended on the organ, the metal dose and direct contact of the stress factor with the organ.

Expression of PnSS Promotes Squalene and Oleanolic Acid (OA) Accumulation in Aralia elata via Methyl Jasmonate (MeJA) Induction

Aralia elata is an important herb due to the abundance of pentacyclic triterpenoid saponins whose important precursors are squalene and OA. Here, we found that MeJA treatment promoted both precursors accumulation, especially the latter, in transgenic A. elata, overexpressing a squalene synthase gene from Panax notoginseng(PnSS). In this study, Rhizobium-mediated transformation was used to express the PnSS gene. Gene expression analysis and high-performance liquid chromatography (HPLC) were used to identify the effect of MeJA on squalene and OA accumulation. The PnSS gene was isolated and expressed in A. elata. Transgenic lines showed a very high expression of the PnSS gene and farnesyl diphosphate synthase gene (AeFPS) and a slightly higher squalene content than the wild-type, but endogenous squalene synthase (AeSS), squalene epoxidase (AeSE), and β-amyrin synthase (Aeβ-AS) gene were decreased as well as OA content. Following one day of MeJA treatment, the expression levels of PeSS, AeSS, and AeSE genes increased significantly. On day 3, the maximum content of both products reached 17.34 and 0.70 mg·g^-1, which increased 1.39- and 4.90-fold than in the same lines without treatment. Transgenic lines expressing PnSS gene had a limited capability to promote squalene and OA accumulation. MeJA strongly activated their biosynthesis pathways, leading to enhance yield.

Polyacetylenes from the adventitious roots of Centella asiatica with glucose uptake stimulatory activity

Centella asiatica (L.) Urban is an herbaceous perennial plant of the Apiaceae family that has diverse medicinal uses. Its active components are saponin, phenolics, and polyacetylenes. Plant cell cultures have been exploited for the efficient production of metabolites with pharmacological activity. In this work, we prepared adventitious root cultures of C. asiatica and analyzed their content and biological activity. Adventitious root extracts were found to increase glucose uptake by differentiated L6 skeletal muscle cells and to be more efficient than the extract of whole plants. Chromatographic fractionation of the extracts from adventitious roots of C. asiatica led to the isolation of two known polyacetylenes, araliadiol (1) and 8-acetoxy-1,9-pentadecadiene-4,6-diyn-3-ol (2), in addition to a new polyacetylene, which we have named centellidiol (3). All the three polyacetylenes stimulated glucose uptake in a dose-dependent manner. The methanol extract of adventitious roots contained 0.53% and 0.82% of compounds 1 and 2, respectively, which are values that were 15 and 21 times higher that are found in mother plants. We therefore suggest that the high content of these polyacetylenes contributes to the high efficacy of C. asiatica adventitious root cultures. Overall, adventitious root cultures of C. asiatica can be part of a secure supply of effective ingredients including polyacetylenes.

Production of anthraquinones from cell and organ cultures of Morinda species

Since ancient times, Morinda species, particularly Morinda citrifolia, have been used for their therapeutic benefits. Iridoids, anthraquinones, coumarins, flavonoids, lignans, phytosterols, and carotenoids are examples of natural substances with bioactivity. Anthraquinone derivatives are the most significant of these chemicals since they are utilized as natural coloring agents and have a wide range of medicinal functions. Utilizing cell and organ cultures of Morinda species, various biotechnological methods have been developed for the bioproduction of anthraquinone derivatives. The generation of anthraquinone derivatives in cell and organ cultures is summarized in this article. The methods used to produce these chemicals in bioreactor cultures have also been examined. KEY POINTS: • This review investigates the potential of cell and organ cultures for anthraquinone synthesis. • The overproduction of anthraquinones has been addressed using a variety of techniques. • The use of bioreactor technologies for anthraquinone manufacturing is highlighted.

Production of Secondary Metabolites from Cell Cultures of Sageretia thea (Osbeck) M.C. Johnst. Using Balloon-Type Bubble Bioreactors

Sageretia thea is used in the preparation of herbal medicine in China and Korea; this plant is rich in various bioactive compounds, including phenolics and flavonoids. The objective of the current study was to enhance the production of phenolic compounds in plant cell suspension cultures of Sageretia thea. Optimum callus was induced from cotyledon explants on MS medium containing 2,4-dichlorophenoxyacetic acid (2,4-D; 0.5 mg L^-1), naphthalene acetic acid (NAA, 0.5 mg L^-1), kinetin (KN; 0.1 mg L^-1) and sucrose (30 g L^-1). Browning of callus was successfully avoided by using 200 mg L^-1 ascorbic acid in the callus cultures. The elicitor effect of methyl jasmonate (MeJA), salicylic acid (SA), and sodium nitroprusside (SNP) was studied in cell suspension cultures, and the addition of 200 µM MeJA was found suitable for elicitation of phenolic accumulation in the cultured cells. Phenolic and flavonoid content and antioxidant activity were determined using 2,2 Diphenyl 1 picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethybenzothiazoline-6-sulphonic acid (ABTS), ferric reducing antioxidant power (FRAP) assays and results showed that cell cultures possessed highest phenolic and flavonoid content as well as highest DPPH, ABTS, and FRAP activities. Cell suspension cultures were established using 5 L capacity balloon-type bubble bioreactors using 2 L of MS medium 30 g L^-1 sucrose and 0.5 mg L^-1 2,4-D, 0.5 mg L^-1 NAA, and 0.1 mg L^-1 KN. The optimum yield of 230.81 g of fresh biomass and 16.48 g of dry biomass was evident after four weeks of cultures. High-pressure liquid chromatography (HPLC) analysis showed the cell biomass produced in bioreactors possessed higher concentrations of catechin hydrate, chlorogenic acid, naringenin, and other phenolic compounds.

Methyl jasmonate and salicylic acid as powerful elicitors for enhancing the production of secondary metabolites in medicinal plants: an updated review

Plant secondary metabolites are bioactive scaffolds that are crucial for plant survival in the environment and to maintain a defense mechanism from predators. These compounds are generally present in plants at a minimal level and interestingly, they are found to have a wide variety of therapeutic values for humans. Several medicinal plants are used for pharmaceutical purposes due to their affordability, fewer adverse effects, and vital role in traditional remedies. Owing to this reason, these plants are exploited at a high range worldwide and therefore many medicinal plants are on the threatened list. There is a need of the hour to tackle this major problem, one effective approach called elicitation can be used to enhance the level of existing and novel plant bioactive compounds using different types of elicitors namely biotic and abiotic. This process can be generally achieved by in vitro and in vivo experiments. The current comprehensive review provides an overview of biotic and abiotic elicitation strategies used in medicinal plants, as well as their effects on secondary metabolites enhancement. Further, this review mainly deals with the enhancement of biomass and biosynthesis of different bioactive compounds by methyl jasmonate (MeJA) and salicylic acid (SA) as elicitors of wide medicinal plants in in vitro by using different cultures. The present review was suggested as a significant groundwork for peers working with medicinal plants by applying elicitation strategies along with advanced biotechnological approaches.

Interactive effects of salicylic acid and jasmonic acid on secondary metabolite production in Echinacea purpurea

Secondary metabolites are highly beneficial to human health and have commercial and industrial values. So, this research aimed to study the effects of exogenous salicylic acid (SA) and jasmonic acid (JA) on some secondary metabolites in purple coneflower. A field experiment as a randomized complete block design with three replications was conducted in Shahrood, Iran. Treatments were the factorial arrangement of 3 SA (0, 0.5, and 1 millimole) and 4 JA concentrations (0, 5, 20, and 50 micromole). The non-linear regression procedure was employed to quantify the relation of these materials with each other. The results indicated that the SA effect on all ten measured secondary metabolites changed with changing the JA levels as there was the interaction between these elicitors. On average, most (7 out of 11) of the combined SA_JA levels up-regulated the production of secondary metabolites as compared to the plants not sprayed with SA and JA. In terms of average response to elicitation with 11 combined SA_JA levels, they ranked from higher to lower as the guaiacol peroxidase, hydrogen proxide (H2O2), polyphenol oxidase, glutathione S-transferase, superoxide dismutase, NADPH oxidase, total phenolic content, phenylalanine ammonia-lyase, anthocyanin, and flavonoid. A few secondary metabolites appeared to have a biphasic relationship with each other. For instance, over lower and medium values of NADPH oxidase activity, anthocyanin content increased linearly with increasing NADPH oxidase activity; over higher values of NADPH oxidase activity, it showed a plateau state.

Foliar methyl jasmonate (MeJA) application increased 2-acetyl-1-Pyrroline (2-AP) content and modulated antioxidant attributes and yield formation in fragrant rice

Endogenous methyl jasmonate (MeJA) mediates abiotic and biotic stresses in plants. Exogenous MeJA application can stimulate and defend plant gene expression and induce plant chemical defense. The effects of foliar MeJA application on yield and 2-acetyl-1-pyrroline (2-AP) biosynthesis of fragrant rice are scarcely investigated. The pot experiment was conducted by spraying different concentrations of MeJA (0, 1, and 2 μM; denoted as CK, MeJA-1, and MeJA-2) at the initial heading stage of two fragrant rice cultivars, Meixiangzhan and Yuxiangyouzhan. The results showed that foliar MeJA application significantly increased the grain 2-AP content by 32.1% and 49.7%, respectively, following MeJA-1 and MeJA-2 treatments, and the two cultivars showed the highest 2-AP content upon MeJA-2 treatment. However, the grain yield was increased in MeJA-1 as compared with MeJA-2 treatment for all rice cultivars and no significant differences were observed in yield and yield-related traits compared with CK. The aroma was improved by foliar MeJA application which was strongly associated with the regulation of the precursors and enzymes involved in 2-AP biosynthesis. In particular, the contents of proline, pyrroline-5-carboxylic acid, and pyrroline at maturity, as well as the activities of proline dehydrogenase, ornithine aminotransferase, and pyrroline-5-carboxylic acid synthetase, were positively correlated with grain 2-AP content. On the other hand, foliar MeJA application improved the contents of soluble protein, chlorophyll a and b, and carotenoid, and increased the activity of antioxidant enzymes. Moreover, peroxidase activity and leaf chlorophyll contents were significantly positively correlated to 2-AP content following foliar MeJA application. Therefore, our results implied that foliar MeJA application increased aroma and influenced yield by regulating the physio-biochemistry characters and resistance, and suggested that the optimal concentration of MeJA for the best positive effect on the yield and aroma was 1 μM. However, further study is required to evaluate the metabolic level and molecular basis of the regulatory mechanism of foliar MeJA application on 2-AP in fragrant rice.

Effect of ascorbate and hydrogen peroxide on hormone and metabolite levels during post-germination growth in wheat

The modulation of hormone and metabolite levels by ascorbate (ASA) and hydrogen peroxide (H₂ O₂ ) was compared during post-germination growth in shoots of wheat. Treatment with ASA resulted in a greater reduction of growth than the addition of H₂ O₂ . ASA also had a larger effect on the redox state of the shoot tissues as shown by the higher ASA and glutathione (GSH) levels, lower glutathione disulfide (GSSG) content and GSSG/GSH ratio compared to the H₂ O₂ treatment. Apart from common responses (i.e., increase of cis-zeatin and its O-glucosides), the contents of several compounds related to cytokinin (CK) and abscisic acid (ABA) metabolism were greater after ASA application. These differences in the redox state and hormone metabolism following the two treatments may be responsible for their distinct influence on various metabolic pathways. Namely, the glycolysis and citrate cycle were inhibited by ASA and they were not affected by H₂ O₂ , while the amino acid metabolism was induced by ASA and repressed by H₂ O₂ based on the changes in the level of the related carbohydrates, organic and amino acids. The first two pathways produce reducing power, while the last one needs it; therefore ASA, as a reductant may suppress and induce them, respectively. H₂ O₂ as an oxidant had different effect, namely it did not alter glycolysis and citrate cycle, and inhibited the formation of amino acids.

Enhanced Production of Active Photosynthetic and Biochemical Molecules in Silybum marianum L. Using Biotic and Abiotic Elicitors in Hydroponic Culture

Elicitors are stressors that activate secondary pathways that lead to the increased production of bioactive molecules in plants. Different elicitors including the fungus Aspergillus niger (0.2 g/L), methyl jasmonate (MeJA, 100 µM/L), and silver nanoparticles (1 µg/L) were added, individually and in combination, in a hydroponic medium. The application of these elicitors in hydroponic culture significantly increased the concentration of photosynthetic pigments and total phenolic contents. The treatment with MeJA (methyl jasmonate) (100 µM/L) and the co-treatment of MeJA and AgNPs (silver nanoparticles) (100 µM/L + 1 µg/L) exhibited the highest chlorophyll a (29 µg g^-1 FW) and chlorophyll b (33.6 µg g^-1 FW) contents, respectively. The elicitor MeJA (100 µM/L) gave a substantial rise in chlorophyll a and b and total chlorophyll contents. Likewise, a significant rise in carotenoid contents (9 µg/g FW) was also observed when subjected to meJA (100 µM/L). For the phenolic content, the treatment with meJA (100 µM/L) proved to be very effective. Nevertheless, the highest production (431 µg/g FW) was observed when treated with AgNPs (1 µg/L). The treatments with various elicitors in this study had a significant effect on flavonoid and lignin content. The highest concentration of flavonoids and lignin was observed when MeJA (100 mM) was used as an elicitor, following a 72-h treatment period. Hence, for different plant metabolites, the treatment with meJA (100 µM/L) and a co-treatment of MeJA and AgNPs (100 µM/L + 1 µg/L) under prolonged exposure times of 120-144 h proved to be the most promising in the accretion of valuable bioactive molecules. The study opens new insights into the use of these elicitors, individually or in combination, by using different concentrations and compositions.

Decipher the molecular evolution and expression patterns of Cupin family genes in oilseed rape

Cupin proteins are involved in plant growth and development as well as in response to various stresses. Here, a total of 173 Cupin genes were identified in Brassica napus, and their molecular evolution and expression patterns were analyzed. These genes were classified into ten groups. Motif and exon-intron structure indicated a high degree of conservation within each group during evolution. BnaCupins were distributed on 19 chromosomes and their expansion is mainly contributed by whole-genome duplication (WGD) and segmental duplication events. BnaCupins have undergone severe purifying selection during a long evolutionary process. Meanwhile, some positive selection sites were identified. Expression patterns and cis-element analysis indicated that BnaCupins play significant roles in plant growth and stress responses. In addition, the expression levels of some BnCupins were significantly altered when treated with different conditions (cold, salt, drought, IAA, ABA, and 6-BA). Some BnaCupin interacting proteins, such as glycosyl hydrolase5 (GHs5), carbohydrate kinase (CHKs), ATP-dependent 6-phosphofructokinase (ATP-PFK), S-adenosylmethionine synthase (S-MAT), and aldolase class II (ALD II), were identified by the protein-protein interaction network. It will contribute to enriching our knowledge of the Cupin gene family in B. napus and provide a basis for further studies of their functions.

Confronting Secondary Metabolites with Water Uptake and Transport in Plants under Abiotic Stress

Phenolic compounds and glucosinolates are secondary plant metabolites that play fundamental roles in plant resistance to abiotic stress. These compounds have been found to increase in stress situations related to plant adaptive capacity. This review assesses the functions of phenolic compounds and glucosinolates in plant interactions involving abiotic stresses such as drought, salinity, high temperature, metals toxicity, and mineral deficiency or excess. Furthermore, their relation with water uptake and transport mediated through aquaporins is reviewed. In this way, the increases of phenolic compounds and glucosinolate synthesis have been related to primary responses to abiotic stress and induction of resistance. Thus, their metabolic pathways, root exudation, and external application are related to internal cell and tissue movement, with a lack of information in this latter aspect.

Fatty acid metabolites of Dendrobium nobile were positively correlated with representative endophytic fungi at altitude

Introduction

Altitude, as a comprehensive ecological factor, regulates the growth and development of plants and microbial distribution. Dendrobium nobile (D. nobile) planted in habitats at different elevations in Chishui city, also shows metabolic differences and endophytes diversity. What is the triangular relationship between altitude, endophytes, and metabolites?

Methods

In this study, the diversity and species of endophytic fungi were tested by ITS sequencing and metabolic differences in plants were tested by UPLC-ESI-MS/MS. Elevation regulated the colonization of plant endophytic fungal species and fatty acid metabolites in D. nobile.

Results

The results indicate that and high altitude was better for the accumulation of fatty acid metabolites. Therefore, the high-altitude characteristic endophytic floras were screened, and the correlation with fatty acid metabolites of plants was built. The colonization of T. rubrigenum, P. Incertae sedis unclassified, Phoma. cf. nebulosa JZG 2008 and Basidiomycota unclassified showed a significantly positive correlation with fatty acid metabolites, especially 18-carbon-chain fatty acids, such as (6Z,9Z,12Z)-octadeca-6,9,12-trienoic acid, 3,7,11,15-tetramethyl-12-oxohexadeca-2,4-dienoic acid and Octadec-9-en-12-ynoic acid. What is more fascinating is these fatty acids are the essential substrates of plant hormones.

Discussion

Consequently, it was speculated that the D. nobile- colonizing endophytic fungi stimulated or upregulated the synthesis of fatty acid metabolites and even some plant hormones, thus affecting the metabolism and development of D. nobile.

Transcriptome analysis reveals that jasmonic acid biosynthesis and signaling is associated with the biosynthesis of asperosaponin VI in Dipsacus asperoides

Dipsacus asperoides is a perennial herb, the roots of which are abundant in asperosaponin VI, which has important medicinal value. However, the molecular mechanism underlying the biosynthesis of asperosaponin VI in D. asperoides remains unclear. In present study, a comprehensive investigation of asperosaponin VI biosynthesis was conducted at the levels of metabolite and transcript during root development. The content of asperosaponin VI was significantly accumulated in two-leaf stage roots, and the spatial distribution of asperosaponin VI was localized in the xylem. The concentration of asperosaponin VI gradually increased in the root with the development process. Transcriptome analysis revealed 3916 unique differentially expressed genes (DEGs) including 146 transcription factors (TFs) during root development in D. asperoides. In addition, α-linolenic acid metabolism, jasmonic acid (JA) biosynthesis, JA signal transduction, sesquiterpenoid and triterpenoid biosynthesis, and terpenoid backbone biosynthesis were prominently enriched. Furthermore, the concentration of JA gradually increased, and genes involved in α-linolenic acid metabolism, JA biosynthesis, and triterpenoid biosynthesis were up-regulated during root development. Moreover, the concentration of asperosaponin VI was increased following methyl jasmonate (MeJA) treatment by activating the expression of genes in the triterpenoid biosynthesis pathway, including acetyl-CoA acetyltransferase (DaAACT), 3-hydroxy-3-methylglutaryl coenzyme A synthase (DaHMGCS), 3-hydroxy-3-methylglutaryl coenzyme-A reductase (DaHMGCR). We speculate that JA biosynthesis and signaling regulates the expression of triterpenoid biosynthetic genes and facilitate the biosynthesis of asperosaponin VI. The results suggest a regulatory network wherein triterpenoids, JA, and TFs co-modulate the biosynthesis of asperosaponin VI in D. asperoides.

Pre- or Post-Harvest Treatment with MeJA Improves Post-Harvest Storage of Lemon Fruit by Stimulating the Antioxidant System and Alleviating Chilling Injury

Cold storage preserves lemon fruit quality; however, it can result in significant chilling injury (CI). The effects of pre- and post-harvest methyl jasmonate (MeJA) treatments at four concentrations (0, 0.1, 0.3, and 0.5 mM) on CI and sensory quality of lemons during 80 d of storage at 7-10 °C were investigated. Both pre- and post-harvest MeJA treatments reduced CI, weight loss (WL) and maintained higher firmness, total soluble solids (TSS), and total acidity (TA) than in the controls. Antioxidant enzyme activities decreased in the control fruit but increased in both pre- and post-harvest MeJA-treated fruit. In addition, phospholipase D (PLD) and lipoxygenase (LOX) activities and malondialdehyde (MDA) content were higher in the control than in the MeJA-treated fruit. Pre-harvest MeJA treatment generally preserved fruit better than post-harvest MeJA treatment, with the best results observed when MeJA was applied at 0.3 mM, which enhanced the antioxidant system of the lemon fruits, thus reducing the post-harvest incidence of chilling injury. These results have important implications for improved fruit quality post-harvest.

Evolutionary Aspects of Hypericin Productivity and Endogenous Phytohormone Pools Evidenced in Hypericum Species In Vitro Culture Model

Shoot cultures of hypericin non-producing H. calycinum L. (primitive Ascyreia section), hypericin-producing H. perforatum L., H. tetrapterum Fries (section Hypericum) and H. richeri Vill. (the evolutionarily most advanced section Drosocarpium in our study) were developed and investigated for their growth, development, hypericin content and endogenous phytohormone levels. Hypericins in wild-growing H. richeri significantly exceeded those in H. perforatum and H. tetrapterum. H. richeri also had the highest hypericin productivity in vitro in medium supplemented with 0.2 mg/L N⁶-benzyladenine and 0.1 mg/L indole-3-butyric acid and H. tetrapterum-the lowest one in all media modifications. In shoot culture conditions, the evolutionarily oldest H. calycinum had the highest content of salicylic acid and total jasmonates in some of its treatments, as well as dominance of the storage form of abscisic acid (ABA-glucose ester) and lowest cytokinin ribosides and cytokinin O-glucosides as compared with the other three species. In addition, the evolutionarily youngest H. richeri was characterized by the highest total amount of cytokinin ribosides. Thus, both evolutionary development and the hypericin production capacity seemed to interact closely with the physiological parameters of the plant organism, such as endogenous phytohormones, leading to the possible hypothesis that hypericin productivity may have arisen in the evolution of Hypericum as a means to adapt to environmental changes.

The Influence of Exogenous Jasmonic Acid on the Biosynthesis of Steroids and Triterpenoids in Calendula officinalis Plants and Hairy Root Culture

The interplay between steroids and triterpenoids, compounds sharing the same biosynthetic pathway but exerting distinctive functions, is an important part of the defense strategy of plants, and includes metabolic modifications triggered by stress hormones such as jasmonic acid. Two experimental models, Calendula officinalis hairy root cultures and greenhouse cultivated plants (pot plants), were applied for the investigation of the effects of exogenously applied jasmonic acid on the biosynthesis and accumulation of steroids and triterpenoids, characterized by targeted GC-MS (gas chromatography-mass spectroscopy) metabolomic profiling. Jasmonic acid elicitation strongly increased triterpenoid saponin production in hairy root cultures (up to 86-fold) and their release to the medium (up to 533-fold), whereas the effect observed in pot plants was less remarkable (two-fold enhancement of saponin biosynthesis after a single foliar application). In both models, the increase of triterpenoid biosynthesis was coupled with hampering the biomass formation and modifying the sterol content, involving stigmasterol-to-sitosterol ratio, and the proportions between ester and glycoside conjugates. The study revealed that various organs in the same plant can react differently to jasmonic acid elicitation; hairy root cultures are a useful in vitro model to track metabolic changes, and enhanced glycosylation (of both triterpenoids and sterols) seems to be important strategy in plant defense response.

Cloning and Characterization of the Gene Encoding HMGS Synthase in Polygonatum sibiricum

The saponins of Polygonatum sibiricum had many pharmacological activities such as antitumor, antioxidation, and blood sugar lowering, which were synthesized by two pathways: mevalonate (MVA) and methylerythritol phosphate (MEP). 3-Hydroxy-3-methylglutaryl coenzyme A synthase (HMGS) was the key enzyme in the MVA synthesis pathway, and its expression level may affect the accumulation of saponins which were the main active ingredients of P. sibiricum. In this study, we successfully cloned HMGS1 and HMGS2 from P. sibiricum and their sequence similarity was 93.71% with 89 different sites. The multiple sequence alignment results indicated that the N-terminal sequences of HMGS were conserved. Phylogenetic analysis showed that P. sibiricum, A. officinalis, N. tazetta, D. nobile, and other relatives had a common evolutionary ancestor. The expression levels of both HMGSs and the total saponin content in different tissues revealed that HMGS expression in rhizomes was positively correlated with total saponin content. Further study of the abiotic stress effect of Methyl Jasmonate (MeJA) demonstrated that the expression of HMGS1 and HMGS2 genes was induced by MeJA, peaked at 24 h, and fell by 48 h. Our present findings would provide a blueprint for future studies of HMGS and its role in triterpenoid biosynthesis in P. sibiricum.

Induction of the Prenylated Stilbenoids Arachidin-1 and Arachidin-3 and Their Semi-Preparative Separation and Purification from Hairy Root Cultures of Peanut (Arachis hypogaea L.)

Prenylated stilbenoids such as arachidin-1 and arachidin-3 are stilbene derivatives that exhibit multiple pharmacological activities. We report an elicitation strategy using different combinations of cyclodextrin, hydrogen peroxide, methyl jasmonate and magnesium chloride to increase arachidin-1 and arachidin-3 production in peanut hairy root cultures. The treatment of hairy root cultures with cyclodextrin with hydrogen peroxide selectively enhanced arachidin-1 yield (132.6 ± 20.4 mg/L), which was 1.8-fold higher than arachidin-3. Similarly, cyclodextrin combined with methyl jasmonate selectively enhanced arachidin-3 yield (178.2 ± 6.8 mg/L), which was 5.5-fold higher than arachidin-1. Re-elicitation of the hairy root cultures further increased the levels of arachidin-1 and arachidin-3 by 24% and 42%, respectively. The ethyl acetate extract of the culture medium was consecutively fractionated by normal- and reversed-phase column chromatography, followed by semi-preparative HPLC purification on a C18 column to yield arachidin-1 with a recovery rate of 32% and arachidin-3 with a recovery rate of 39%, both at higher than 95% purity. This study provided a sustainable strategy to produce high-purity arachidin-1 and arachidin-3 using hairy root cultures of peanuts combined with column chromatography and semi-preparative HPLC.

Influence of exogenous phytohormone supplementation on the pigment and fatty acid content of three marine diatoms

Diatoms are ubiquitous photosynthetic microorganisms with great potential for biotechnological applications. However, their commercialisation is hampered by production costs, requiring hence optimisation of cultivation methods. Phytohormones are plant growth regulators which may be used to influence physiological processes in microalgae, including diatoms. In this study, the model species Phaeodactylum tricornutum (Phaeodactylaceae) and two Irish isolates of Stauroneis sp. (Stauroneidaceae) and Nitzschia sp. (Bacillariaceae) were grown with varying amounts of the phytohormones indoleacetic acid (IAA), gibberellic acid (GA3), methyl jasmonate (MJ), abscisic acid (ABA) or salicylic acid (SA), and their influence on pigment and fatty acid profiles was monitored. The application of GA3 (200 mg/l) stimulated the growth of P. tricornutum which accumulated 52% more dry biomass compared to the control and concomitantly returned the highest eicosapentaenoic acid (EPA) yield (0.6 mg/l). The highest fucoxanthin yield (0.18 mg/l) was obtained for P. tricornutum cultivated with GA3 (2 mg/l) supplementation. In Stauroneis sp., SA (1 mg/l) had the most positive effect on EPA, the content of which was enhanced up to 45.7 μg/mg (4.6% of total dry weight). The SA (1 mg/l) treatment also boosted carotenogenesis in Nitzschia sp., leading to 1.7- and 14-fold increases in fucoxanthin and β-carotene compared to the control, respectively. Of note, MJ (0.5 mg/l) increased the EPA content of all diatom species compared to their controls. These results indicate that phytohormone-based treatments can be used to alter the pigment and lipid content of microalgae, which tend to respond in dose- and species-specific manners to individual compounds.Key points• Response to phytohormones was investigated in diatoms from distinct families.• MJ (0.5 mg/l) caused an increase in EPA cellular content in all three diatoms.• Phytohormones mostly caused dose-dependent and species-specific responses.

Jasmonates in plant growth and development and elicitation of secondary metabolites: An updated overview

Secondary metabolites are incontestably key specialized molecules with proven health-promoting effects on human beings. Naturally synthesized secondary metabolites are considered an important source of pharmaceuticals, food additives, cosmetics, flavors, etc., Therefore, enhancing the biosynthesis of these relevant metabolites by maintaining natural authenticity is getting more attention. The application of exogenous jasmonates (JAs) is well recognized for its ability to trigger plant growth and development. JAs have a large spectrum of action that covers seed germination, hypocotyl growth regulation, root elongation, petal expansion, and apical hook growth. This hormone is considered as one of the key regulators of the plant's growth and development when the plant is under biotic or abiotic stress. The JAs regulate signal transduction through cross-talking with other genes in plants and thereby deploy an appropriate metabolism in the normal or stressed conditions. It has also been found to be an effective chemical elicitor for the synthesis of naturally occurring secondary metabolites. This review discusses the significance of JAs in the growth and development of plants and the successful outcomes of jasmonate-driven elicitation of secondary metabolites including flavonoids, anthraquinones, anthocyanin, xanthonoid, and more from various plant species. However, as the enhancement of these metabolites is essentially measured via in vitro cell culture or foliar spray, the large-scale production is significantly limited. Recent advancements in the plant cell culture technology lay the possibilities for the large-scale manufacturing of plant-derived secondary metabolites. With the insights about the genetic background of the metabolite biosynthetic pathway, synthetic biology also appears to be a potential avenue for accelerating their production. This review, therefore, also discussed the potential manoeuvres that can be deployed to synthesis plant secondary metabolites at the large-scale using plant cell, tissue, and organ cultures.