Application of a three dimensional polyethyleneimine functionalized graphene oxide aerogel as an adsorbent for the determination of phytohormones in ginseng.

Aerogels have attracted considerable attention in sample pretreatment for their outstanding properties, such as the unique porous structure, large surface area and abundant modifiable active sites. The present research reports a three-dimensional interconnected porous network aerogel (PEI-AGO) manufactured based on graphene oxide (GO), polyethyleneimine (PEI) and agar as basic materials through a vacuum freeze-drying treatment. The PEI-AGO aerogel exhibits great potential as a solid phase extraction adsorbent for the selective purification of six endogenous plant hormones in conjunction with high performance liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS). Several factors affecting the extraction efficiency were investigated. Under the optimized extraction conditions, a wide linear range of 0.5-100 ng mL-1 with a good linearity (r > 0.9934) was observed. Low limits of detection (LODs) and limits of quantification (LOQs) were obtained in the range of 0.032-0.155 ng mL-1 and 0.107-0.518 ng mL-1, respectively. Furthermore, the relative recoveries for spiked ginseng samples exhibited remarkable consistency, ranging from 90.2% to 117.6%, with a relative standard deviation (RSD) of ≤9.4% (n = 3). In summary, PEI-AGO has proven to be an effective adsorbent for the pretreatment and enrichment of phytohormones which can be used for the determination of trace endogenous acidic plant hormones in ginseng leaves.

Characterization of Endophytic Fungi, Acremonium sp., from Lilium davidii and Analysis of Its Antifungal and Plant Growth-Promoting Effects.

The present study was aimed at isolating endophytic fungi from the Asian culinary and medicinal plant Lilium davidii and analyzing its antifungal and plant growth-promoting effects. In this study, the fungal endophyte Acremonium sp. Ld-03 was isolated from the bulbs of L. davidii and identified through morphological and molecular analysis. The molecular and morphological analysis confirmed the endophytic fungal strain as Acremonium sp. Ld-03. Antifungal effects of Ld-03 were observed against Fusarium oxysporum, Botrytis cinerea, Botryosphaeria dothidea, and Fusarium fujikuroi. The highest growth inhibition, i.e., 78.39 ± 4.21%, was observed for B. dothidea followed by 56.68 ± 4.38%, 43.62 ± 3.81%, and 20.12 ± 2.45% for B. cinerea, F. fujikuroi, and F. oxysporum, respectively. Analysis of the ethyl acetate fraction through UHPLC-LTQ-IT-MS/MS revealed putative secondary metabolites which included xanthurenic acid, valyl aspartic acid, gancidin W, peptides, and cyclic dipeptides such as valylarginine, cyclo-[L-(4-hydroxy-Pro)-L-leu], cyclo(Pro-Phe), and (3S,6S)-3-benzyl-6-(4-hydroxybenzyl)piperazine-2,5-dione. Other metabolites included (S)-3-(4-hydroxyphenyl)-2-((S)-pyrrolidine-2-carboxamido)propanoic acid, dibutyl phthalate (DBP), 9-octadecenamide, D-erythro-C18-Sphingosine, N-palmitoyl sphinganine, and hydroxypalmitoyl sphinganine. The strain Ld-03 showed indole acetic acid (IAA) production with or without the application of exogenous tryptophan. The IAA ranged from 53.12 ± 3.20 µg ml-1 to 167.71 ± 7.12 µg ml-1 under different tryptophan concentrations. The strain was able to produce siderophore, and its production was significantly decreased with increasing Fe(III) citrate concentrations in the medium. The endophytic fungal strain also showed production of organic acids and phosphate solubilization activity. Plant growth-promoting effects of the strain were evaluated on in vitro seedling growth of Allium tuberosum. Application of 40% culture dilution resulted in a significant increase in root and shoot length, i.e., 24.03 ± 2.71 mm and 37.27 ± 1.86 mm, respectively, compared to nontreated control plants. The fungal endophyte Ld-03 demonstrated the potential of conferring disease resistance and plant growth promotion. Therefore, we conclude that the isolated Acremonium sp. Ld-03 should be further investigated before utilization as a biocontrol agent and plant growth stimulator.

The In Vitro Interaction of 12-Oxophytodienoic Acid and Related Conjugated Carbonyl Compounds with Thiol Antioxidants.

α,ß-unsaturated carbonyls interfere with numerous plant physiological processes. One mechanism of action is their reactivity toward thiols of metabolites like cysteine and glutathione (GSH). This work aimed at better understanding these interactions. Both 12-oxophytodienoic acid (12-OPDA) and abscisic acid (ABA) conjugated with cysteine. It was found that the reactivity of α,ß-unsaturated carbonyls with GSH followed the sequence trans-2-hexenal < 12-OPDA ≈ 12-OPDA-ethylester < 2-cyclopentenone << methyl vinylketone (MVK). Interestingly, GSH, but not ascorbate (vitamin C), supplementation ameliorated the phytotoxic potential of MVK. In addition, 12-OPDA and 12-OPDA-related conjugated carbonyl compounds interacted with proteins, e.g., with members of the thioredoxin (TRX)-fold family. 12-OPDA modified two cysteinyl residues of chloroplast TRX-f1. The OPDAylated TRX-f1 lost its activity to activate the Calvin-Benson-cycle enzyme fructose-1,6-bisphosphatase (FBPase). Finally, we show that 12-OPDA interacts with cyclophilin 20-3 (Cyp20-3) non-covalently and affects its peptidyl-prolyl-cis/trans isomerase activity. The results demonstrate the high potential of 12-OPDA as a diverse interactor and cellular regulator and suggest that OPDAylation may occur in plant cells and should be investigated as novel regulatory mechanism.

A Dissipation Pattern of Gibberellic Acid and Its Metabolite, Isogibberellic Acid, during Tea Planting, Manufacturing, and Brewing.

As a widely used plant growth regulator, the gibberellic acid (GA3) residue in tea has potential risk for human health. Herein, the degradation of GA3 and its conversion into main metabolites were investigated during tea planting, manufacturing, and brewing using ultrahigh-performance liquid chromatography tandem mass spectrometry. The metabolite iso-GA3 was first discovered during the tea production chain and identified using Q-Exactive Orbitrap mass spectrometry. GA3 dissipated following first-order kinetics in tea shoots with half-lives ranging from 2.46 to 2.74 days. It was degraded into iso-GA3 in tea shoots, which had a longer residual period than GA3. Meanwhile, external application of GA3 could increase the proportion of growth-promoting endogenous phytohormones and lead to rapid growth of tea plants. During tea manufacturing, iso-GA3 was quickly and massively converted from GA3. Fixing (heat at 220-230 °C) played an important role in the dissipation of GA3 and iso-GA3 during green tea manufacturing, but there were high residues of iso-GA3 in black tea. High transfer rates (77.3 to 94.5%) of GA3 and iso-GA3 were observed during tea brewing. These results could provide a practical reference for food safety in tea and other agricultural products and the guidance for scientific application of GA3 in tea planting.

Determination of thirteen acidic phytohormones and their analogues in tea (Camellia sinensis) leaves using ultra high performance liquid chromatography tandem mass spectrometry.

Trace plant hormones play an important role in tea growth, development and quick response to biotic and abiotic stresses. However, lack of a sensitive method limits the research on plant hormone regulation for tea quality and yields. Herein, a highly sensitive method was developed using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for profiling and quantification of 13 acidic phytohormones and their analogues, including auxins, abscisic acid and gibberellins in fresh tea leaves. After optimizing the different C18 columns and mobile phase systematically, an Agilent Eclipse Plus C18 column combined with the mobile phase A (acetonitrile) and B (water) was employed. Target acidic phytohormones were extracted using acidified methanol, and tea matrices were cleaned up by dispersive solid phase adsorbents of polyvinylpolypyrrolidone (PVPP) and graphitized carbon black (GCB) followed by polymer-based mixed-mode cation-exchange solid phase extraction. The method showed good linearity for all 13 analytes with regression coefficients (R2) > 0.998. Satisfactory recoveries of 12 analytes spiked with three levels ranged from 71.8% to 109.9%, while intra-day and inter-day precisions were below 20%. Limits of detection (LODs) and limits of quantitation (LODs) for 12 acidic phytohormones were 0.1-4.2 µg kg-1 and 0.3-13.9 µg kg-1, respectively. Finally, this method was firstly employed to analyze 13 analytes in fresh tea leaves (with the treatment of dormancy, light qualities, exogenous hormones and infestation of pests), highlighting its sufficient capability for rapid analysis of multiclass phytohormones in agriculture field.

NMR-based metabolomics and bioassays to study phytotoxic extracts and putative phytotoxins from Mediterranean plant species.

INTRODUCTION: Mediterranean plants are characterised by a high content of bioactive secondary metabolites that play important roles in plant-plant interactions as plant growth regulators and could be useful for the development of new eco-friendly herbicides. OBJECTIVE: An NMR-based metabolomics approach was reported to seek selective phytotoxic plant extracts and putative plant-derived active molecules. METHODS: Plant extracts derived from five Mediterranean donor species (Pistacia lentiscus, Bellis sylvestris, Phleum subulatum, Petrohrhagia saxifraga and Melilotus neapolitana) were used to treat the hydroponic cultures of three receiving plants (Triticum durum, Triticum ovatum and Avena fatua). Morphological analyses of the treated receiving plants were carried out. NMR-based metabolomics was applied both to characterise the donor plant extracts and to study the effects of the treatments on the receiving plants. RESULTS: This study allowed the identification of Melilotus neapolitana and Bellis sylvestris as phytotoxic plant and good candidates for further studies. Specifically, the NMR-based metabolomics investigation showed that these species affect a specific set of metabolites (such as sugars, amino and organic acids) and therefore metabolic pathways [i.e. tricarboxylic acid (TCA) cycle, amino acid metabolism, etc.] that are crucial for the plant growth and development. Moreover, it was possible to identify the metabolite(s) probably responsible for the phytotoxicity of the active extracts. CONCLUSION: The NMR-based metabolomics approach employed in this study led to the identification of two phytotoxic plant extracts and their putative active principles. These new insights will be of paramount importance in the future to find plant derived molecules endowed with phytotoxic activities.

Virulence mechanisms of plant-pathogenic Streptomyces species: an updated review.

Gram-positive Actinobacteria from the genus Streptomyces are best known for their morphological complexity and for their ability to produce numerous bioactive specialized metabolites with useful applications in human and veterinary medicine and in agriculture. In contrast, the ability to infect living plant tissues and to cause diseases of root and tuber crops such as potato common scab (CS) is a rare attribute among members of this genus. Research on the virulence mechanisms of plant-pathogenic Streptomyces spp. has revealed the importance of the thaxtomin phytotoxins as key pathogenicity determinants produced by several species. In addition, other phytotoxic specialized metabolites may contribute to the development or severity of disease caused by Streptomyces spp., along with the production of phytohormones and secreted proteins. A thorough understanding of the molecular mechanisms of plant pathogenicity will enable the development of better management procedures for controlling CS and other plant diseases caused by the Streptomyces.

Effect of Major Tea Insect Attack on Formation of Quality-Related Nonvolatile Specialized Metabolites in Tea ( Camellia sinensis) Leaves.

Insect attack is known to induce a high accumulation of volatile metabolites in tea ( Camellia sinensis). However, little information is available concerning the effect of insect attack on tea quality-related nonvolatile specialized metabolites. This study aimed to investigate the formation of characteristic nonvolatile specialized metabolites in tea leaves in response to attack by major tea insects, namely, tea green leafhoppers and tea geometrids, and determine the possible involvement of phytohormones in metabolite formation resulting from insect attack. Both tea green leafhopper and tea geometrid attacks increased the jasmonic acid and salicylic acid contents. The abscisic acid content was only increased under tea green leafhopper attack, perhaps due to special continuous piercing-sucking wounding. Tea green leafhopper attack induced the formation of theaflavins from catechins under the action of polyphenol oxidase, while tea geometrid attack increased the l-theanine content. Exogenous phytohormone treatments can affect the caffeine and catechin contents. These results will help to determine the influence of major tea pest insects on important tea quality-related metabolites and enhance understanding of the relationship of phytohormones and quality-related nonvolatile metabolite formation in tea exposed to tea pest insect attacks.

Evaluation of Anti-microbial Activity of Ex vitro and Callus Extracts from Commiphora gileadensis.

BACKGROUND AND OBJECTIVE: Commiphora gileadensis a medicinal plant rare species. A large amount of plant materials were needed to produce secondary metabolite under in vitro culture. Therefore, callus is used in the in vitro culture, since it can proliferate quickly and continuously provide an appropriate amount of plant which used for extracting the antimicrobial compounds from C. gileadensis. MATERIAL AND METHODS: Rapid protocol for optimum callus production has been assessed to overcome limitations of the conventional propagation methods. The effect of plant growth regulator (PGR) on the regeneration of C. gileadensis was investigated for callus induction experiment using a standard MS medium with various concentrations of 6-Benzyl adenine (BA), Kinetin (Kn), 2,4-dichlorophenoxy acetic acid (2,4-D) and naphthalene acetic acid (NAA) at 0.0, 0.5, 1.0,1.5, 2.0 and 2.5 mg L-1. RESULTS: The result showed that the maximum regeneration of callus induced the fresh and dry weight were obtained 5675±1321 and 376.7±56.9 mg, respectively on MS media containing 2 mg L-1 2,4D + 0.5 mg L-1 BA after 12 weeks. The anti-bacterial and anti-fungal activities of C. gileadensis were evaluated using the callus and ex vitro extracts, six bacterial species fungal genera were used the agar well diffusion method used of 25, 50, 75 and 100 µL methanolic or ethonlic extracts of ex vitro and callus had considerable inhibition effects on the tested bacteria and fungi. CONCLUSION: Callus culture technique may be an important tool to get the C. gileadensis quickly as compared to the natural growth phenomenon where it takes many years. Moreover, it's give us an opportunity to get the active constituent without destroying the plant available in nature. The results of the present study can improve our understanding of the economic importance of C. gileadensis as activity ingredient antimicrobial agent and provided methods for its preparation.

Heterotic patterns of primary and secondary metabolites in the oilseed crop Brassica juncea.

Heterosis refers to the superior performance of F1 hybrids over their respective parental inbred lines. Although the genetic and expression basis of heterosis have been previously investigated, the metabolic basis for this phenomenon is poorly understood. In a preliminary morphological study in Brassica juncea, we observed significant heterosis at the 50% flowering stage, wherein both the growth and reproduction of F1 reciprocal hybrids were greater than that of their parents. To identify the possible metabolic causes or consequences of this heterosis, we carried out targeted LC-MS analysis of 48 primary (amino acids and sugars) and secondary metabolites (phytohormones, glucosinolates, flavonoids, and phenolic esters) in five developmental tissues at 50% flowering in hybrids and inbred parents. Principal component analysis (PCA) of metabolites clearly separated inbred lines from their hybrids, particularly in the bud tissues. In general, secondary metabolites displayed more negative heterosis values in comparison to primary metabolites. The tested primary and secondary metabolites displayed both additive and non-additive modes of inheritance in F1 hybrids, wherein the number of metabolites showing an additive mode of inheritance were higher in buds and siliques (52.77-97.14%) compared to leaf tissues (47.37-80%). Partial least regression (PLS) analysis further showed that primary metabolites, in general, displayed higher association with morphological parameters in F1 hybrids. Overall, our results are consistent with a resource-cost model for heterosis in B. juncea, where metabolite allocation in hybrids appears to favor growth, at the expense of secondary metabolism.

Isolation and identification of a growth inhibitory substance from Heliotropium indicum L.

Heliotropium indicum L. belongs to the family Boraginaceae. The plant has been used as a folk medicine because it contains substances of various biological activities. It is also identified as a common weed which grows wildly in crop fields in tropical and subtropical regions of the world. However, there is little information on the allelopathic effect in this plant. Therefore, this study was undertaken to investigate the growth inhibitory effect and to identify the growth inhibitory substances in H. indicum. An aqueous methanol extract of H. indicum inhibited shoot and root growth of barnyard grass, foxtail fescue, timothy, cress, lettuce and rapeseed at concentrations higher than 10 mg dry weight equivalent extract/mL. The concentrations required for 50% growth inhibition (I50) of those test plants ranged from 3-282 mg dry weight equivalent extract/mL. The extract was then separated using a sequence of chromatographic fractionations and a growth inhibitory substance was isolated and identified by spectral analysis as methyl caffeate. Methyl caffeate inhibited the growth of lettuce and foxtail fescue at concentrations higher than 1.0 mM. The results suggest that methyl caffeate may contribute to the growth inhibitory effect of H. indicum and may play an important role in the allelopathic effect of H. indicum.

Method for Ultrarapid High-Content Screening for Biologically Active Chemicals Using Plant Pollen.

Chemical genomics attracts considerable attention by offering crucial tools for plant biology to regulate plant growth and development. However, most chemical screens are time consuming and laborious, and require a high input of resources. Here we describe a broadly applicable method for the ultrarapid high-content phenotypic screening of small chemical compound libraries for new plant growth regulators. The assay is based on determination of pollen tube growth and can be completed in less than 8 h. Using this method, we identified novel inhibitors and modulators of plant growth and showed that compounds selected using a Nicotiana tabacum-based assay were biologically active in other plants, such as Arabidopsis thaliana.

Manipulation of Plant Growth Regulators on Phytochemical Constituents and DNA Protection Potential of the Medicinal Plant Arnebia benthamii.

Arnebia benthamii of the family Boraginaceae is a critically endangered nonendemic plant of the Kashmir Himalayas and is used to treat a number of human diseases. The current study was based on developing an in vitro micropropagation protocol vis-à-vis induction of various secondary metabolites under in vitro conditions for the possible biological activity. A tissue culture protocol was developed for A. benthamii for the first time in the Himalayan region using varied combinations and proper media formulations, including various adjuvants: Murashige and Skoog (MS) media, growth hormones, sugars, agar, and so forth. The influence of different media combinations was estimated, and the MS + thidiazuron (TDZ) + indole 3-acetic acid (IAA) combination favors a higher regeneration potential. The higher amounts of chemical constituents were also recorded on the same treatment. The in vitro plant samples also showed a noteworthy effect of scavenging of hydroxyl radicals vis-à-vis protection from oxidative DNA damage. The in vitro raised plants are good candidates for the development of antioxidant molecules.

Sensitive determination of brassinosteroids by solid phase boronate affinity labeling coupled with liquid chromatography-tandem mass spectrometry.

Brassinosteroids (BRs) are regarded as the sixth plant hormone that is widely distributed in the plant kingdom. Sensitive quantification of BRs will be greatly benefit to illuminate the detail mechanisms about how BRs play crucial role in plant developmental processes such as cell division, cell expansion, cytodifferentiation, seed germination, vegetative growth and resisting biological or abiotic stress. In the current study, we developed a method for rapid and sensitive determination of endogenous BRs in plant tissues by combining LC-MS and a novel sample preparation strategy, in which the plant tissue extract was supplied to solid phase boronate affinity labeling and extraction, followed by desorption and salt-induced phase transition extraction for further purification. Under the optimized conditions, good linearity was obtained for 6 BR with correlation coefficients (r) ranging from 0.9988 to 0.9999. The limits of detection (LODs, S/N = 3) ranged from 1.4 to 2.8 pg mL-1. The recoveries were between 93.4% and 116.2% with the relative standard deviations (RSDs) ranging from 2.8% to 15.8%. Finally, the developed method was successfully applied to the analysis of 6 endogenous BR in various plant tissues including 20 mg FW Oryza sativa shoot, 10 mg FW Oryza sativa root, 20 mg FW Arabidopsis thaliana shoot, 4 Arabidopsis thaliana flowers (2.8 mg) and one Brassica napus stamen (3.0 mg) with concentration ranging from 0.26 to 157.28 ng g-1 FW.

The Potential of Phytomelatonin as a Nutraceutical.

Phytomelatonin (plant melatonin) is chemically related to the amino acid tryptophan and has many diverse properties. Phytomelatonin is an interesting compound due to its outstanding actions at the cellular and physiological level, especially its protective effect in plants exposed to diverse stress situations, while its vegetable origin offers many opportunities because it is a natural compound. We present an overview of its origin, its action in plants in general (particularly in plant species with high levels of phytomelatonin), and its possibilities for use as a nutraceutical with particular attention paid to the beneficial effects that it may have in human health. The differences between synthetic melatonin and phytomelatonin, according to its origin and purity, are presented. Finally, the current market for phytomelatonin and its limits and potentials are discussed.

Ureidopyrazine Derivatives: Synthesis and Biological Evaluation as Anti-Infectives and Abiotic Elicitors.

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) has become a frequently deadly infection due to increasing antimicrobial resistance. This serious issue has driven efforts worldwide to discover new drugs effective against Mtb. One research area is the synthesis and evaluation of pyrazinamide derivatives as potential anti-TB drugs. In this paper we report the synthesis and biological evaluations of a series of ureidopyrazines. Compounds were synthesized by reacting alkyl/aryl isocyanates with aminopyrazine or with propyl 5-aminopyrazine-2-carboxylate. Reactions were performed in pressurized vials using a CEM Discover microwave reactor with a focused field. Purity and chemical structures of products were assessed, and the final compounds were tested in vitro for their antimycobacterial, antibacterial, and antifungal activities. Propyl 5-(3-phenylureido)pyrazine-2-carboxylate (compound 4, MICMtb = 1.56 µg/mL, 5.19 µM) and propyl 5-(3-(4-methoxyphenyl)ureido)pyrazine-2-carboxylate (compound 6, MICMtb = 6.25 µg/mL, 18.91 µM) had high antimycobacterial activity against Mtb H37Rv with no in vitro cytotoxicity on HepG2 cell line. Therefore 4 and 6 are suitable for further structural modifications that might improve their biological activity and physicochemical properties. Based on the structural similarity to 1-(2-chloropyridin-4-yl)-3-phenylurea, a known plant growth regulator, two selected compounds were evaluated for similar activity as abiotic elicitors.

Protocol for Extraction and Isolation of Brassinosteroids from Plant Tissues.

Brassinosteroids (BRs) are a class of steroid plant hormones that participate with other plant hormones in the regulation of numerous developmental processes, including root and shoot growth, vascular differentiation, fertility, and seed germination. A characteristic feature of all plant hormones, including BRs, is that their concentration is extremely low in plant tissues and, therefore, the methods dealing with their determination belong to ultra-trace analysis, for which very sensitive analytical tools are needed. The analysis of natural BRs is essential when their functions and roles in plant growth and development are to be elucidated. Here, we describe a reliable protocol for high-throughput extraction and purification of BRs. The procedure consists of two solid-phase extraction steps and provides selective enrichment and efficient cleanup of these compounds from complex plant extracts. The protocol is designed for sensitive liquid chromatography-tandem mass spectrometry-based method for simultaneous detection of 22 naturally occurring BRs, including their biosynthetic precursors and most of their biologically active metabolites, without need for derivatization.

Postharvest Application of Oligochitosan and Chitosan Reduces Calyx Alterations of Citrus Fruit Induced by Ethephon Degreening Treatment.

In the present study, we investigated whether the postharvest application of oligochitosan and chitosan could be used as potential alternatives to 2,4-dichlorophenoxyacetic acid (2,4-D) treatment to prevent calyx senescence of mandarin fruits induced by degreening treatment. The results of scanning electron microscopy indicated that the ethephon degreening treatment could accelerate the formation of pedicel abscission layers. Treatments with 15 g kg-1 oligochitosan, 5 g kg-1 chitosan, and 50 mg kg-1 2,4-D significantly suppressed the formation of pedicel abscission layers of ethephon degreening fruit and inhibited the browning of the calyx. These two treatments delayed the degradation of protopectin, cellulose, and lignin. Inhibition of the increase in the abscisic acid (ABA) content was also observed in these two treatments. In conclusion, these two treatments, particularly 15 g kg-1 oligochitosan, could be potentially used as alternatives to 2,4-D to improve calyx alterations induced by the ethephon degreening treatment in mandarin fruits.

Biological Activity of Vegetal Extracts Containing Phenols on Plant Metabolism.

The influence of vegetal extracts derived from red grape, blueberry fruits and hawthorn leaves on Zea mays L. plant growth and the activity of phenylalanine ammonia-lyase (PAL), a key enzyme of the phenylpropanoid pathway, was investigated in laboratory experiments. The extracts were characterized using FT-IR and Raman spectroscopies in order to obtain a pattern of the main functional groups. In addition, phenols content was determined by HPLC, whereas the content of indoleacetic acid and isopentenyladenosine hormones was determined by ELISA test and the auxin and gibberellin-like activities by plant-bioassays. The treated maize revealed increased root and leaf biomass, chlorophyll and sugars content with respect to untreated plants. Hawthorn, red grape skin and blueberry at 1.0 mL/L induced high p-coumaric content values, whilst hawthorn also showed high amounts of gallic and p-hydroxybenzoic acids. PAL activity induced by hawthorn at 1.0 mL/L had the highest values (11.1-fold UNT) and was strongly and linearly related with the sum of leaf phenols. Our results suggest that these vegetal extracts contain more than one group of plant-promoting substances.

Reproduction of the Medicinal Plant Pelargonium sidoides via Somatic Embryogenesis.

The medicinal plant Pelargonium sidoides DC. (Geraniaceae) was traditionally used for the treatment of the common cold and cough in South Africa. Today an aequous-ethanolic root extract from this plant is approved for the treatment of acute bronchitis and is globally marketed also as an immunostimulant. The increasing demand of the plant material for the industrial production indicates the need of new effective methods for the propagation of P. sidoides. Here we report somatic embryogenesis and in vitro plantlet regeneration from somatic cells of inflorescence shoots and petioles of P. sidoides. A one-week cultivation of explants in media containing different concentrations of thidiazuron (1, 2.2, 3, and 4 mg/L) followed by a cultivation period without phytohormones resulted in the induction of somatic embryos within 2-4 weeks. After 2-4 months, the embryos generated roots and could be transferred into a greenhouse, where flower formation took place and the development of seeds occurred with high germination rates. The root umckalin concentration, determined by high-performance thin-layer chromatography, was comparable to that of seed-cultivated plants (100 ± 6 vs. 113 ± 10 µg umckalin/g dried roots). For the first time, direct somatic embryogenesis has been established as an appropriate cultivation method for P. sidoides plants used as raw material in the pharmaceutical industry. Moreover, genetically identical plants (chemical races) can be easily generated by this procedure.