Comprehensive elucidation of the differential physiological kale response to cytokinins under in vitro conditions.

BACKGROUND: Kale, a versatile cruciferous crop, valued for its pro-health benefits, stress resistance, and potential applications in forage and cosmetics, holds promise for further enhancement of its bioactive compounds through in vitro cultivation methods. Micropropagation techniques use cytokinins (CKs) which are characterized by various proliferative efficiency. Despite the extensive knowledge regarding CKs, there remains a gap in understanding their role in the physiological mechanisms. That is why, here we investigated the effects of three CKs - kinetin (Kin), 6-benzylaminopurine (BAP), and 2-isopentenyladenine (2iP) - on kale physiology, antioxidant status, steroidal metabolism, and membrane integrity under in vitro cultivation. RESULTS: Our study revealed that while BAP and 2iP stimulated shoot proliferation, they concurrently diminished pigment levels and photosynthetic efficiency. Heightened metabolic activity in response to all CKs was reflected by increased respiratory rate. Despite the differential burst of ROS, the antioxidant properties of kale were associated with the upregulation of guaiacol peroxidase and the scavenging properties of ascorbate rather than glutathione. Notably, CKs fostered the synthesis of sterols, particularly sitosterol, pivotal for cell proliferation and structure of membranes which are strongly disrupted under the action of BAP and 2iP possibly via pathway related to phospholipase D and lipoxygenase which were upregulated. Intriguingly, both CKs treatment spurred the accumulation of sitostenone, known for its ROS scavenging and therapeutic potential. The differential effects of CKs on brassicasterol levels and brassinosteroid (BRs) receptor suggest potential interactions between CKs and BRs. CONCLUSION: Based on the presented results we conclude that the effect evoked by BAP and 2iP in vitro can improve the industrial significance of kale because this treatment makes possible to control proliferation and/or biosynthesis routes of valuable beneficial compounds. Our work offers significant insights into the nuanced effects of CKs on kale physiology and metabolism, illuminating potential avenues for their application in plant biotechnology and medicinal research.

Divergent contribution of the MVA and MEP pathways to the formation of polyprenols and dolichols in Arabidopsis.

Isoprenoids, including dolichols (Dols) and polyprenols (Prens), are ubiquitous components of eukaryotic cells. In plant cells, there are two pathways that produce precursors utilized for isoprenoid biosynthesis: the mevalonate (MVA) pathway and the methylerythritol phosphate (MEP) pathway. In this work, the contribution of these two pathways to the biosynthesis of Prens and Dols was addressed using an in planta experimental model. Treatment of plants with pathway-specific inhibitors and analysis of the effects of various light conditions indicated distinct biosynthetic origin of Prens and Dols. Feeding with deuteriated, pathway-specific precursors revealed that Dols, present in leaves and roots, were derived from both MEP and MVA pathways and their relative contributions were modulated in response to precursor availability. In contrast, Prens, present in leaves, were almost exclusively synthesized via the MEP pathway. Furthermore, results obtained using a newly introduced here 'competitive' labeling method, designed so as to neutralize the imbalance of metabolic flow resulting from feeding with a single pathway-specific precursor, suggest that under these experimental conditions one fraction of Prens and Dols is synthesized solely from endogenous precursors (deoxyxylulose or mevalonate), while the other fraction is synthesized concomitantly from endogenous and exogenous precursors. Additionally, this report describes a novel methodology for quantitative separation of 2H and 13C distributions observed for isotopologues of metabolically labeled isoprenoids. Collectively, these in planta results show that Dol biosynthesis, which uses both pathways, is significantly modulated depending on pathway productivity, while Prens are consistently derived from the MEP pathway.

Modifications in steroid and triterpenoid metabolism in Calendula officinalis plants and hairy root culture in response to chitosan treatment.

BACKGROUND: Chitosan, a deacetylated derivative of chitin, is one of the most preferred biopolymers for use as biostimulants and biofertilizers in organic agriculture and as elicitors to enhance the productivity of plant in vitro cultures. Valued as a non-toxic, biodegradable, and environment-friendly agent, it is widely applied to improve plant growth and yield, the content of bioactive specialized metabolites, and resistance to stress conditions and pathogens. However, the influence of chitosan on the growth-defense trade-off, particularly the interplay between steroid and triterpenoid metabolism, has not been extensively investigated. RESULTS: In this study, Calendula officinalis pot plants and hairy root cultures exposed to chitosan treatment displayed reduced biomass and altered steroid and triterpenoid metabolism. Biosynthesis and accumulation of free forms of sterols (particularly stigmasterol) were inhibited, while the content of sterol esters increased remarkably. The content of some triterpenoids (mainly free triterpenoid acids) was slightly enhanced; however, the biosynthesis of triterpenoid saponins was negatively affected. CONCLUSIONS: These results indicate that in certain plants, chitosan treatment might not positively influence the growth and metabolite production. Therefore, to avoid unexpected effects, initial studies of the conditions of chitosan treatment are recommended, including the dose and the number of chitosan applications, the type of treatment (e.g., foliar or soil), and the vegetative stage of the treated plants.

Triterpenoid and Steroid Content of Lipophilic Extracts of Selected Medicinal Plants of the Mediterranean Region.

The available phytochemical characteristics of the medicinal plants and derived herbal material often lack data concerning the content of steroids (including phytosterols) and triterpenoids, that can be responsible for various beneficial properties and therapeutic effects, either directly, or as a result of synergistic action with other bioactive constituents. The aim of the present work was the analysis of the content of these compounds in herbal material (leaves, aerial parts) derived from selected medicinal plants (Cistus ladanifer, Cistus monspeliensis, Erica arborea, Globularia alypum, Pistacia lentiscus, Rhamnus alaternus), widely used in folk medicine in the Mediterranean region. Results obtained by gas chromatography-mass spectrometry (GC-MS)-targeted profiling revealed the diversity in the profiles and contents of steroids and triterpenoids in the analyzed plant material, ranging from 5.7% d.w. in E. arborea to 0.1% in G. alypum. The obtained results supplement the existing phytochemical data of the investigated medicinal plants, pointing to the E. arborea aerial parts and P. lentiscus leaves as valuable resources of phytosterols and bioactive triterpenoids.

Heterologous production and characterization of a pyomelanin of Antarctic Pseudomonas sp. ANT_H4: a metabolite protecting against UV and free radicals, interacting with iron from minerals and exhibiting priming properties toward plant hairy roots.

BACKGROUND: Antarctica has one of the most extreme environments in the world. This region is inhabited by specifically adapted microorganisms that produce various unique secondary metabolites (e.g. pigments) enabling their survival under the harsh environmental conditions. It was already shown that these natural, biologically active molecules may find application in various fields of biotechnology. RESULTS: In this study, a cold-active brown-pigment-producing Pseudomonas sp. ANT_H4 strain was characterized. In-depth genomic analysis combined with the application of a fosmid expression system revealed two different pathways of melanin-like compounds biosynthesis by the ANT_H4 strain. The chromatographic behavior and Fourier-transform infrared spectroscopic analyses allowed for the identification of the extracted melanin-like compound as a pyomelanin. Furthermore, optimization of the production and thorough functional analyses of the pyomelanin were performed to test its usability in biotechnology. It was confirmed that ANT_H4-derived pyomelanin increases the sun protection factor, enables scavenging of free radicals, and interacts with the iron from minerals. Moreover, it was shown for the first time that pyomelanin exhibits priming properties toward Calendula officinalis hairy roots in in vitro cultures. CONCLUSIONS: Results of the study indicate the significant biotechnological potential of ANT_H4-derived pyomelanin and open opportunities for future applications. Taking into account protective features of analyzed pyomelanin it may be potentially used in medical biotechnology and cosmetology. Especially interesting was showing that pyomelanin exhibits priming properties toward hairy roots, which creates a perspective for its usage for the development of novel and sustainable agrotechnical solutions.

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.

Modulation of Steroid and Triterpenoid Metabolism in Calendula officinalis Plants and Hairy Root Cultures Exposed to Cadmium Stress.

The present study investigated the changes in the content of steroids and triterpenoids in C. officinalis hairy root cultures and plants exposed to cadmium stress. The observed effects included the content and composition of analyzed groups of compounds, particularly the proportions among individual sterols (e.g., stigmasterol-to-sitosterol ratio), their ester and glycoside conjugates. The total sterol content increased in roots (by 30%) and hairy root culture (by 44%), whereas it decreased in shoots (by 15%); moreover, these effects were inversely correlated with Cd-induced growth suppression. Metabolic alterations of sterols and their forms seemed to play a greater role in the response to Cd stress in roots than in shoots. The symptoms of the competition between general metabolites (sterols) and specialized metabolites (triterpenoids) were also observed, i.e., the increase of the sterol biosynthesis parallel to the decrease of the triterpenoid content in C. officinalis plant roots and hairy root culture, and the inverse phenomenon in shoots. The similarity of the metabolic modifications observed in the present study on C. officinalis plant roots and hairy roots confirmed the possibility of application of plant in vitro cultures in initial studies for physiological research on plant response to environmental stresses.

Distribution of Triterpenoids and Steroids in Developing Rugosa Rose (Rosarugosa Thunb.) Accessory Fruit.

Triterpenoids and steroids are considered to be important for the fruit quality and health-promoting properties for the consumers. The aim of the study was the determination of the changes in triterpenoid and steroid biosynthesis and the accumulation in hypanthium and achenes of rugosa rose (Rosa rugosa Thunb.) hip during fruit development and ripening at three different phenological stages (young fruits, fully developed unripe fruits, and matured fruits). Triterpenoids and steroids were also determined in the peel and the pulp of the matured hips. The obtained results indicated that the distribution of the analyzed compounds in different fruit tissues is a selective process. The increased rate of hydroxylation of triterpenoids, the deposition of hydroxylated acids in fruit surface layer, and the continuous biosynthesis of phytosterols in achenes versus its gradual repression in hypanthium accompanied by the accumulation of their biosynthetic intermediates and ketone derivatives seem to be characteristic metabolic features of maturation of rugosa rose accessory fruit. These observations, apart from providing the important data on metabolic modifications occurring in developing fruits, might have a practical application in defining fruit parts, particularly rich in bioactive constituents, to enable the development of novel functional products.

Variations in Triterpenoid Deposition in Cuticular Waxes during Development and Maturation of Selected Fruits of Rosaceae Family.

The process of fruit ripening involves many chemical changes occurring not only in the mesocarp but also in the epicarp, including changes in the triterpenoid content of fruit cuticular waxes that can modify the susceptibility to pathogens and mechanical properties of the fruit surface. The aim of the study was the determination of the ripening-related changes in the triterpenoid content of fruit cuticular waxes of three plant species from the Rosaceae family, including rugosa rose (Rosa rugosa), black chokeberry (Aronia melanocarpa var. "Galicjanka") and apple (Malus domestica var. "Antonovka"). The triterpenoid and steroid content in chloroform-soluble cuticular waxes was determined by a GC-MS/FID method at four different phenological stages. The profile of identified compounds was rather similar in selected fruit samples with triterpenoids with ursane-, oleanane- and lupane-type carbon skeletons, prevalence of ursolic acid and the composition of steroids. Increasing accumulation of triterpenoids and steroids, as well as the progressive enrichment of the composition of these compounds in cuticular wax during fruit development, was observed. The changes in triterpenoid content resulted from modifications of metabolic pathways, particularly hydroxylation and esterification, that can alter interactions with complementary functional groups of aliphatic constituents and lead to important changes in fruit surface quality.

Influence of Selected Abiotic Factors on Triterpenoid Biosynthesis and Saponin Secretion in Marigold (Calendula officinalis L.) in Vitro Hairy Root Cultures.

The aim of the study was the evaluation of the efficiency of selected abiotic elicitors, i.e., silver and cadmium ions, ultrasound, and UV-C irradiation, in the stimulation of triterpenoid biosynthesis, accumulation, and saponin secretion in Calendula officinalis hairy root cultures. Apart from the possible enhancement of triterpenoid production, the relationship between primary and secondary metabolism (represented respectively by sterols and pentacyclic triterpenes), modifications of the sterol compositional profile, and fluctuations in the total triterpenoid content were monitored in the performed experiments. The main phenomenon observed as a response to heavy metal treatment was the stimulation (up to 12-fold) of the secretion of saponins, accompanied by significant changes in sterol composition. Ultrasound stimulated the secretion of saponins (up to 11-fold); however, it exerted diverse influences on the triterpenoid content in hairy root tissue (stimulating or decreasing) depending on the duration of the exposure to the elicitor. UV-C radiation caused a slight increase in the content of both sterols and saponins in hairy root tissue, and stimulated saponin secretion up to 8.5-fold. The expected symptoms of the competition between the biosynthetic pathways of sterols and pentacyclic triterpenoids were less evident in reactions to abiotic stressors than those reported previously for biotic elicitors.

Various Patterns of Composition and Accumulation of Steroids and Triterpenoids in Cuticular Waxes from Screened Ericaceae and Caprifoliaceae Berries during Fruit Development.

Cuticular waxes are primarily composed of two classes of lipids: compounds derived from very-long-chain fatty acids and isoprenoids, particularly triterpenoids and steroids. Isoprenoids can occur in cuticular waxes in high amounts, dominating the mixture of aliphatic long-chain hydrocarbons, while in other plants they are found in trace concentrations. Triterpenoids occurring in fruit cuticular waxes are of interest due to their potential role in the protection against biotic stresses, including pathogen infections, and their impact on the mechanical toughness of the fruit surface, maintaining fruit integrity, and post-harvest quality. The aim of the present study was the determination of the changes in the triterpenoid profile of the fruit cuticular waxes of four plant species bearing edible berries: Vaccinium myrtillus, V. vitis-idaea, and Arbutus unedo of the Ericaceae and the edible honeysuckle Lonicera caerulea of the Caprifoliaceae. Triterpenoids were identified and quantified by GC-MS/FID (gas chromatography-mass spectrometry/flame ionization detection) at three different phenological stages: young berries, berries at the onset of ripening, and mature berries. During fruit development and maturation, the triterpenoid content in cuticular waxes displayed species-specific patterns of changes. The steroid content seemed to be directly correlated with the developmental stage, with a very typical point of transition between growth and ripening being observed in all the fruit analyzed in this study.

Modeling of Dolichol Mass Spectra Isotopic Envelopes as a Tool to Monitor Isoprenoid Biosynthesis.

The cooperation of the mevalonate (MVA) and methylerythritol phosphate (MEP) pathways, operating in parallel in plants to generate isoprenoid precursors, has been studied extensively. Elucidation of the isoprenoid metabolic pathways is indispensable for the rational design of plant and microbial systems for the production of industrially valuable terpenoids. Here, we describe a new method, based on numerical modeling of mass spectra of metabolically labeled dolichols (Dols), designed to quantitatively follow the cooperation of MVA and MEP reprogrammed upon osmotic stress (sorbitol treatment) in Arabidopsis (Arabidopsis thaliana). The contribution of the MEP pathway increased significantly (reaching 100%) exclusively for the dominating Dols, while for long-chain Dols, the relative input of the MEP and MVA pathways remained unchanged, suggesting divergent sites of synthesis for dominating and long-chain Dols. The analysis of numerically modeled Dol mass spectra is a novel method to follow modulation of the concomitant activity of isoprenoid-generating pathways in plant cells; additionally, it suggests an exchange of isoprenoid intermediates between plastids and peroxisomes.

Extraction of Triterpenic Acids and Phytosterols from Apple Pomace with Supercritical Carbon Dioxide: Impact of Process Parameters, Modelling of Kinetics, and Scaling-Up Study.

Apple pomace, a byproduct of juice production, is a rich source of bioactive compounds and nutrients. Supercritical fluid extraction was proposed as a method for a fast and selective extraction of hydrophobic compounds with a pharmaceutical potential from this matrix. Chromatographic analysis showed that the pomace contained significant amounts of such substances, the most abundant of them were ursolic acid, oleanolic acid, and ß-sitosterol. The solubility was chosen as a primary factor for a selection of the extraction conditions; the best results were acquired for a temperature of 80 °C and a pressure of 30 MPa. The equation proposed by Chrastil was applied for the description of the impact of the process parameters on the solubility of the analytes; the obtained values of coefficients of determination were satisfactory, despite the fact that the equation was developed for binary systems. The extraction curves obtained during the experiments were used for the description of the process kinetics using the Broken plus Intact Cell model. The impact of the temperature, pressure, and flow rate of carbon dioxide on the mass transfer phenomena was investigated. The data obtained allowed the prediction of the extraction curve for the process conducted on the larger scale.

Characterization of triterpenoid profiles and triterpene synthase expression in the leaves of eight Vitis vinifera cultivars grown in the Upper Rhine Valley.

Plant triterpenoids are a diverse group of secondary metabolites with wide distribution, high chemical diversity and interesting pharmacological and antimicrobial properties. The first step in the biosynthesis of all triterpenoids is the cyclization of the 2,3-oxidosqualene precursor, catalyzed by oxidosqualene cyclases (OSCs), which have characteristic product specificities. Biosynthesis and functions of pentacyclic triterpenes have been poorly studied in grapevine. In this study, we first investigated the profile of triterpenoids present in leaf cuticular waxes from eight Vitis vinifera cultivars cultivated in the Upper Rhine Valley. Further quantification of triterpenoids showed that these cultivars can be divided into two groups, characterized by high levels of lupeol (e.g., Pinot noir) or taraxerol (e.g., Gewurztraminer) respectively. We further analyzed the OSC family involved in the synthesis of pentacyclic triterpenes (called VvTTPSs) in the sequenced V. vinifera 40024 genome and found nine genes with similarity to previously characterized triterpene synthases. Phylogenetic analysis further showed that VvTTPS1-VvTTPS3 and VvTTPS5-VvTTPS9 belong to the ß-amyrin synthase and multifunctional triterpene synthase clade, whereas VvTTPS10 belongs to the lupeol synthase clade. We studied the expression of several members of the VvTTPS family following biotic and abiotic stresses in V. vinifera 40024 as well as in the eight healthy cultivars. This study further revealed that one candidate gene, VvTTPS5, which does not belong to the lupeol synthase clade, is highly expressed in lupeol-rich cultivars. VvTTPS3, VvTTPS5, VvTTPS6, VvTTPS7 and VvTTPS10 were highly upregulated by UV stress, but only VvTTPS3, VvTTPS5, VvTTPS6 and VvTTPS10 were upregulated following downy mildew and gray mold infections respectively. These results suggest differential roles of VvTTPS against environmental stresses in grape leaves.

Changes in Heligmosomoides polygyrus glycoprotein pattern by saponins impact the BALB/c mice immune response.

Saponins of marigold (Calendula officinalis), in particular derivatives of 3-O-monoglucuronide of oleanolic acid, are able to reduce infectivity of Heligmosomoides polygyrus in mice. The purpose of this study was to understand the immune activation provoked by third-stage larvae exposed to marigold glucuronides. We also examined the pattern of glycosylation of larval antigens which appeared to be crucial for induction of cytokine production in BALB/c mice; higher concentrations of IL-6, IFN-γ, IL-10 and TNF-α were observed in serum or intestine one week post infection. Three weeks later, in the chronic phase of infection, cells in culture were able to produce IL-6, IFN-γ, TNF-α and IL-17. Restimulation of cells with H. polygyrus antigen resulted in reduced production of IL-6, and TNF-α. The pattern of cytokine production co-existed with reduced expression of terminal glucose, α-linked mannose, N-acetyl-galactosamine, ß-galactose, N-acetyl-glucosamine and α-fucose in several protein bands. Galactose, as a new terminal carbohydrate residue appeared in 20-24kDa protein bands. The number of immunogenic epitopes in parasitic antigens was reduced; only three protein bands of 56, 26 and 12kDa were recognized by IgG1. These studies provide a model system to find the glycosylated molecules expressed on nematodes that improve establishment and survival and characterize cytokine production in mice infected with larvae exposed to saponin. Identification of these molecules is the first step in the recognition of key antigenic epitopes able to induce protective or tolerogenic immune responses.

Correction: Edorh Tossa et al. Flowers and Inflorescences of Selected Medicinal Plants as a Source of Triterpenoids and Phytosterols. Plants 2023, 12, 1838.

In the original publication [...].

Flowers and Inflorescences of Selected Medicinal Plants as a Source of Triterpenoids and Phytosterols.

Steroids and triterpenoids are compounds valued for their various biological and pharmacological properties; however, their content in medicinal and edible plants is often understudied. Flowers have been consumed since the ancient times as a part of traditional cuisine and as alternative medicines. Currently, the interest in medicinal and edible flowers is growing since contemporary consumers are incessantly seeking innovative natural sources of bioactive compounds. The aim of this report was the GC-MS (gas-chromatography-mass spectrometry) analysis of steroid and triterpenoid content in flowers, inflorescences and leaves of several plants (Berberis vulgaris L., Crataegus laevigata (Poir.) DC., Pulsatilla vulgaris Mill., Rosa rugosa Thunb., Sambucus nigra L. and Vinca minor L.), applied in herbal medicine in various forms, including isolated flowers (Flos), inflorescences (Inflorescentia) or aerial parts (Herba, i.e., combined flowers, leaves and stems). The most abundant source of triterpenoids was V. minor flowers (6.3 mg/g d.w.), whereas the steroids were prevailing in P. vulgaris flowers (1.8 and 1.1 mg/g). The profiles of triterpenoid acids and neutral triterpenoids in C. laevigata and S. nigra inflorescences were particularly diverse, involving compounds belonging to lupane-, oleanane- and ursane-type skeletons. The obtained results revealed that some flowers can constitute an abundant source of phytosterols and bioactive triterpenoids, valuable for utilization in functional foods, dietary supplements and cosmetic products.

Combined omics approaches expose metabolite-microbiota correlations in grape berries of three cultivars of Douro wine region.

This study hypothesized the existence of cultivar-associated correlations between grape berry metabolites and its microbial residents, in Douro wine region. Integrated metabolomics with metabarcoding showed that the microbial biodiversity is not associated to berry sugar concentration, but closely connected to the profile of amino acids, flavonoids and wax compounds, which drove cultivar differentiation together with the prevalence of pathogenic fungi, yeasts and bacteria, mainly Dothideomycetes and Gammaproteobacteria. Over 7000 metabolite-microbiota correlations with ρ >|0.99| exposed a core of 15 metabolites linked to 11 microbial taxa. Serine, oxalate, cyanidin-3-O-glucoside, petunidin-3-O-glucoside, gallic acid, germanicol, sitosterol and erythrodiol correlated negatively to the abundance of most taxa, including Alternaria, Aureobasidium, Pseudopithomyces, Pseudomonas and Sphingomonas. In contrast, phenylalanine, asparagine, alanine, (epi)gallocatechin and procyanidin gallate mediated positive metabolite-OTU correlations. E. necator and A. carbonarius correlated negatively with stigmasterol and amyrin. Complex fungi-bacteria relationships ruled by Dothideomycetes and Alphaproteobacteria further suggest tight host-microbe interactions at the carposphere.

Fruit cuticular waxes as a source of biologically active triterpenoids.

The health benefits associated with a diet rich in fruit and vegetables include reduction of the risk of chronic diseases such as cardiovascular disease, diabetes and cancer, that are becoming prevalent in the aging human population. Triterpenoids, polycyclic compounds derived from the linear hydrocarbon squalene, are widely distributed in edible and medicinal plants and are an integral part of the human diet. As an important group of phytochemicals that exert numerous biological effects and display various pharmacological activities, triterpenoids are being evaluated for use in new functional foods, drugs, cosmetics and healthcare products. Screening plant material in the search for triterpenoid-rich plant tissues has identified fruit peel and especially fruit cuticular waxes as promising and highly available sources. The chemical composition, abundance and biological activities of triterpenoids occurring in cuticular waxes of some economically important fruits, like apple, grape berry, olive, tomato and others, are described in this review. The need for environmentally valuable and potentially profitable technologies for the recovery, recycling and upgrading of residues from fruit processing is also discussed.

Metabolic Modifications in Terpenoid and Steroid Pathways Triggered by Methyl Jasmonate in Taxus × media Hairy Roots.

The in vitro cultures of Taxus spp. were one of the first plant in vitro systems proved to exert the positive effect of elicitation with methyl jasmonate (MeJA) on the biosynthesis of specialized metabolites. The main aim of the present study is to examine the effect of MeJA treatment on the steroid and triterpenoid content of two genetically different hairy root lines of Taxus × media, KT and ATMA. The results revealed that the two lines differed in the total content of steroids and triterpenoids (in the ATMA root line, their amounts were lower than those in the KT line by 43% and 30%, respectively), but not in the composition of these compounds. The metabolic response to elicitation with MeJA was different: in the KT root line, the content of steroids decreased by 18%, whereas it increased by 38% in the ATMA line. Several metabolic features were common, including the characteristic changes in the ratio of sitosterol to stigmasterol content, caused by the very sharp boost in stigmasterol levels, the increase in the amount of glycoside forms of sterols, as well as in triterpenoid and total phenolic content. It is the first report on modifications of the terpenoid biosynthetic pathway in Taxus hairy root cultures triggered by MeJA, concerning steroids and triterpenoids.