Variation In Secondary Metabolites Research Articles

Seasonal changes in the phenolic compound contents and bioactivities in Betula platyphylla bark determined by soil properties

The white birch (Betula platyphylla Suk.) is widespread in eastern Asia, and its bark is a valuable resource for secondary metabolite extraction. Limited information is available regarding seasonal variations of secondary metabolites in white birch bark. In our study, we analyzed the phenolic compound contents and bioactivities of white birch bark in different seasons and their relationship to climatic factors and soil properties. The data suggested that the levels of total phenol, total flavonoid, seven individual phenolic compounds, and bioactivities all peaked in September. The antioxidant activity was positively correlated with the contents of phenolic compounds. Soil microbial properties like microbial biomass nitrogen (MBN) and soil urease activities (URE) explained more than 40% of the variation in phenolic compound contents. This study highlighted that seasons regulate the contents of phenolic compounds and bioactivities by influencing soil microbial properties. The soil with low microbial activity was more favorable for the accumulation of secondary metabolites.

Phylosymbiosis and metabolomics resolve phenotypically plastic and cryptic sponge species in the genus Agelas across the Caribbean basin.

Fundamental to holobiont biology is recognising how variation in microbial composition and function relates to host phenotypic variation. Sponges often exhibit considerable phenotypic plasticity and also harbour dense microbial communities that function to protect and nourish hosts. One of the most prominent sponge genera on Caribbean coral reefs is Agelas. Using a comprehensive set of morphological (growth form, spicule), chemical and molecular data on 13 recognised species of Agelas in the Caribbean basin, we were able to define only five species (=clades) and found that many morphospecies designations were incongruent with phylogenomic and population genetic analyses. Microbial communities were also strongly differentiated between phylogenetic species, showing little evidence of cryptic divergence and relatively low correlation with morphospecies assignment. Metagenomic analyses also showed strong correspondence to phylogenetic species, and to a lesser extent, geographical and morphological characters. Surprisingly, the variation in secondary metabolites produced by sponge holobionts was explained by geography and morphospecies assignment, in addition to phylogenetic species, and covaried significantly with a subset of microbial symbionts. Spicule characteristics were highly plastic, under greater impact from geographical location than phylogeny. Our results suggest that while phenotypic plasticity is rampant in Agelas, morphological differences within phylogenetic species affect functionally important ecological traits, including the composition of the symbiotic microbial communities and metabolomic profiles.

Regional and Irrigation-Induced Variations in Secondary Metabolites of Calotropis procera Flowers in Different Agro-Climatic Zones of Rajasthan

Calotropis procera, a species of family Asclepiadaceae is known in traditional system of medicine from centuries due to its property of curing a number of ailments. It is a xerophytic shrub found in tropical regions of Asia and Africa. It’s flower is useful in anorexia, indigestion and intestinal worm infestation, dysentry, abdominal disorders etc. It is used in many Ayurvedic, Unani and Siddha formulations. Hence investigation on the regional and irrigation-induced variations in secondary metabolites of Calotropis procera flowers across diverse agro-climatic zones in Rajasthan, India, was taken up to find best region for their collection. The study shows that ACZ IIIA has the highest petroleum ether extract content and ACZ V displays elevated methanol extract yields. Within ACZ IB, involving Hanumangarh and Suratgarh, contrasting results in petroleum ether extract and methanol extract yields are observed, with petroleum ether extract higher in the irrigated area and methanol higher in the non-irrigated region. ACZ V demonstrates the maximum total extractive yield, while ACZ IB shows minimum values. Flowers from the irrigated area in Hanumangarh (ACZ IB) exhibit lower values for sterols and alkaloids compared to those from Suratgarh, the non-irrigated region, indicating a complex interplay of environmental factors. The observed variations provide insights into the environmental influences on secondary metabolite content of Calotropis procera flowers, contributing to a deeper understanding from ecological and agricultural perspectives.

Correlation analysis of secondary metabolites and disease resistance activity of different varieties of Congou black tea based on LC-MS/MS and TCMSP

To investigate the correlation between the difference of secondary metabolites and the disease-resistance activity of different varieties of Congou black tea. Among a total of 657 secondary metabolites identified, 183 metabolites had anti-disease activity, 113 were key active ingredients in traditional Chinese medicine (TCM), 73.22% had multiple anti-disease activities, and all were mainly flavonoids and phenolic acids. The main enriched metabolic pathways were phenylpropanoid biosynthesis, biosynthesis of secondary metabolites, flavonoid biosynthesis, and metabolic pathways. Flavonoid and phenolic acid secondary metabolites were more correlated with anti-disease activity and key active TCM ingredients. Conclusion: The types of JGY and Q601 Congou black tea of the relative contents show large differences in secondary metabolites. Flavonoid and phenolic acid secondary metabolites were identified as the primary factors contributing to the variation in secondary metabolites among different varieties of Congou black tea. These compounds also exhibited a stronger correlation with disease resistance activity.

Divergent geographic variation in above‐ versus below‐ground secondary metabolites of Reynoutria japonica

Abstract Secondary metabolites play an important role in plant adaptation, because they can mitigate biotic and abiotic environmental stresses. However, their production and allocation incur different costs and benefits, and are therefore subject to trade‐offs, which are less studied. To understand large‐scale geographic patterns of secondary metabolites, and their environmental drivers and trade‐offs, we studied 39 natural populations of the perennial herb Japanese knotweed (Reynoutria japonica) along a large latitudinal gradient in China. We measured the concentrations of six polyphenols in leaves and rhizomes of R. japonica, and associated the variation in these metabolites with biotic and abiotic environmental factors as well as with functional plant traits and putative costs of secondary metabolites. We found that climate was an important driver of variation in secondary metabolites, both above‐ and below‐ground. Remarkably, the patterns of association differed between leaves and rhizomes, as well as between putative low‐cost versus high‐cost compounds. While annual mean temperature was a stronger predictor of above‐ground metabolites, annual precipitation was more frequently associated with variation in below‐ground metabolites. Moreover, annual temperature was positively associated with high‐cost metabolites, but negatively with low‐cost metabolites. Above‐ground secondary metabolites were generally more strongly associated with functional traits (e.g. specific leaf area) than below‐ground metabolites, and in all cases the directions of correlation were opposite for low‐cost versus high‐cost metabolites above‐ground. The patterns of association also varied with latitude such that leaf concentrations of low‐cost metabolites (quercetin) increased but those of high‐cost metabolites (resveratrol, piceid and emodin) decreased at higher latitudes. In rhizomes, in contrast, the concentrations of high‐cost metabolites (piceid and emodin) increased with latitude. Synthesis. Our findings indicate that allocation strategies differ between above‐ and below‐ground tissues of Reynoutria japonica. As latitude increases, R. japonica invests relatively more into below‐ground metabolites. We propose that reduced high‐cost metabolites in the leaves at higher latitudes may help to conserve nutrients after defoliation, while maintaining high‐cost metabolites in rhizomes may be important for persistent allelopathic effects and resource conservation below‐ground. The divergent patterns of above‐ and below‐ground metabolite allocation thus likely reflect the multiple functions of metabolites and the plants' adaptation to different environments.

A highly efficient protocol for isolation of protoplast from China, Assam and Cambod types of tea plants [Camellia sinensis (L.) O. Kuntze

BackgroundTea is the most popular beverage worldwide second only to water. Its demand is tremendously rising due to increased awareness of its medicinal importance. The quality and uses of tea depend on the tea-types which are mainly three types including China, Assam and Cambod type having distinct compositions of secondary metabolites. Huge variation in secondary metabolites in different tea-types and cultivars limited the successful application of various approaches used for its trait improvement. The efficiency of a protocol for isolation of protoplast is specific to the types and cultivars of tea plants. The existing tea protoplast-isolation protocols [which were optimized for tea-types (China and Assam type) and Chinese cultivars grown in China] were found ineffective on types/cultivars grown in India due to type/cultivar variability. Therefore, optimization of protoplast-isolation protocol is essential for tea-types/cultivars grown in India, as it is the second largest producer of tea and the largest producer of black tea. Here, efforts were made to develop an efficient protoplast-isolation protocol from all major types of tea (China, Assam and Cambod types) grown in India and also from three types of tender leaves obtained from field-grown, hydroponically-grown and tissue culture-grown tea plants.ResultsDeveloped protoplast-isolation protocol was effective for different types of leaf tissue obtained from the tender leaves of field-grown, hydroponically-grown and tissue culture-grown tea plants. Moreover, optimized protocol effectively worked on all three types of tea including China, Assam and Cambod types cultivated in India. The digestion of leaves with 3% cellulase R-10, 0.6% macerozyme, 1% hemicellulase and 4% polyvinylpyrrolidone for 12 h at 28ºC yielded approximately 3.8–4.6 × 107 protoplasts per gram fresh tissue and 80–95% viability in selected tea cultivars, and tissue culture plant material was found most appropriate for protoplast isolation.ConclusionsIn conclusion, we reported an efficient protocol for isolation of protoplasts from tender tea leaves of all major tea-types (China, Assam and Cambod) grown in India. Moreover, the protocol is also effective for tender-leaf tissue of field-grown, hydroponically-grown and tissue culture-grown tea plants. The findings are expected to contribute to the genetic improvement of tea traits widely.

Study on the Dynamic Changes in Non-Volatile Metabolites of Rizhao Green Tea Based on Metabolomics.

The processing of tea leaves plays a crucial role in the formation of the taste of the resulting tea. In order to study the compositions of and changes in taste-related substances during the processing of Rizhao green tea, non-targeted metabolomics was used, based on UHPLC-Q Exactive MS. Totals of 529, 349, and 206 non-volatile metabolites were identified using three different detection modes, of which 112 secondary metabolites were significantly changed. Significant variations in secondary metabolites were observed during processing, especially during the drying stage, and the conversion intensity levels of non-volatile metabolites were consistent with the law of "Drying > Fixation > Rolling". The DOT method was used to screen tea-quality-related compounds that contributed significantly to the taste of Rizhao green tea, including (-)-epicatechin gallate, (-)-epicatechin gallate, gallic acid, L-theanine, and L-leucine, which make important contributions to taste profiles, such as umami and bitterness. Metabolic pathway analysis revealed that purine metabolism, caffeine metabolism, and tyrosine metabolism perform key roles in the processing of Rizhao green tea in different processing stages. The results of this study provide a theoretical basis for tea processing and practical advice for the food industry.

Resistance in Soybean Genotypes to Whitefly <i>Bemisia Tabaci</i>

This study demonstrates the defensive responses of eight soybean genotypes based on plant metabolites to the whitefly Bemisia tabaci. At two sampling intervals (30 and 50 days after sowing) secondary metabolites viz., total phenols, o-dihydroxy phenols, flavonols and tannins and primary metabolites viz., total soluble sugars, reducing sugars and total soluble proteins have been estimated from uninfested and infested soybean plants (125 whitefly adults/plant). The genotypes revealed significant variation in secondary metabolites while primary metabolites decreased. The correlation between whitefly and metabolites showed that secondary metabolites were significantly negatively correlated incidence while primary metabolites were significantly positively correlated.

Variation of secondary metabolites in Cannabis sativa L. inflorescences under applied agrotechnological measures

Industrial hemp is a multi-purpose plant which contains various biologically active compounds and has a broad application in numerous markets. The study aims to investigate industrial hemp variety Felina 32 growing potential in the Nordic-Baltic region, to assess the impact of fertilization by mineral, organic and combined fertilizers on plants secondary metabolites accumulation into their inflorescence. In addition, sowing density (15 and 35 kg/ha) influence on fatty acids methyl esters, cannabinoids, essential oil yield and composition were taken into the qualitative and quantitative evaluation. The results reveal that tested agronomical practice tested significantly affected fatty acids and essential oil yield. Increased sowing density 2.3 times from 15 kg/ha to 35 kg/ha slightly increased CBD content (+ ∼23 %) in hemp inflorescence. 73 volatile compounds were found in the essential oil composition of which the highest amount showed sesquiterpenes: (E)-β-caryophyllene, caryophyllene oxide and humulene epoxide II. The research performed strengthens the hypothesis that industrial hemp could be cultivated in the North-Baltic climate as a multi-use crop through complete utilization of the plant material using inflorescences to produce essential oils as a source of natural antioxidants, flavour and fragrance additives.

Physiological responses and variation in secondary metabolite content among Thai holy basil cultivars (Ocimum tenuiflorum L.) grown under controlled environmental conditions in a plant factory.

Holy basil (Ocimum Tenuiflorum L.) is a widely used herb containing several bioactive compounds of interest for the food and pharmaceutical industries. Plant factories using artificial lighting (PFAL) is a modern agricultural system that offers opportunity to improve crop production and stabilizes productivity in many herbal plants. However, little is known about the variation among holy basil varieties that can be cultivated and provide reasonable biomass and bioactive compounds in PFAL. We therefore evaluated 10 Thai accessions and two commercial cultivars in a PFAL (with hydroponic cultivation) to categorize cultivar characteristics by investigating physiological responses and secondary metabolite variation at plant flowering stage. Among Thai varieties, net photosynthetic rate (Pn) was significantly highest in varieties OC059 and OC081. The greatest growth and biomass measures were observed in OC064. Antioxidant capacity also varied, with the greatest accumulation of total phenolic compounds (TPC), flavonoids, and antioxidant activity by DPPH assay in OC064, and highest terpenoid content in OC194. The accumulation of major compounds confirmed by showing the highest levels of eugenol in OC057, OC063, OC194, and OC195 and methyl eugenol in OC072 and OC081. The highest α-humulene content was found in OC059. PCA based on physiological responses and secondary metabolites indicate that OC064 was clearly distinguished from other cultivars/accessions. These findings demonstrate variation across holy basil accessions for physiologic responses, antioxidant capacity, and secondary compounds in PFAL. These insights lead to identification of suitable varieties which is the most important step of developing an efficient method for producing high quality raw materials of Thai holy basil for supplying the foods and pharmaceutical industries.

Genomic and metabolomic profiling of endolithic Rhodococcus fascians strain S11 isolated from an arid serpentine environment.

Genomic and metabolomic studies of endolithic bacteria are essential for understanding their adaptations to extreme conditions of the rock environment and their contributions to mineralization and weathering processes. The endoliths of arid serpentine rocks are exposed to different environmental stresses, including desiccation and re-hydration, temperature fluctuations, oligotrophy, and high concentrations of heavy metals. Bacteria of the genus Rhodococcus commonly inhabit endolithic environments. Here, we describe genomic and metabolomic analyses of the non-pathogenic wild-type Rhodococcus fascians strain S11, isolated from weathered serpentine rock at the arid Khalilovsky massif, Russia. We found that strain S11 lacks the virulence plasmid that functions in the phytopathogenecity of some R. fascians strains. Phenotypic profiling revealed a high pH tolerance, phytase activity and siderophore production. A widely untargeted metabolome analysis performed using an Orbitrap LC-MS/MS method demonstrated the presence of chrysobactin-type siderophores in the culture medium of strain S11. The natural variation of secondary metabolites produced by strain S11 might provide a practical basis for revealing antibacterial, fungicide or insecticidal activities. Finally, plant infection and plant growth stimulation studies showed no observable effect of exposure strain S11 bacteria on the aerial and root parts of Arabidopsis thaliana plants. Based on our findings, R. fascians strain S11 might be promising tool for investigations of organo-mineral interactions, heavy metal bioremediation, and mechanisms of bacterial mediated weathering of plant-free serpentine rock to soil.

Secondary Metabolite Variation and Bioactivities of Two Marine Aspergillus Strains in Static Co-Culture Investigated by Molecular Network Analysis and Multiple Database Mining Based on LC-PDA-MS/MS.

Co-culture is known as an efficient way to explore the metabolic potential of fungal strains for new antibiotics and other therapeutic agents that could counter emerging health issues. To study the effect of co-culture on the secondary metabolites and bioactivities of two marine strains, Aspergillus terreus C23-3 and Aspergillus. unguis DLEP2008001, they were co-cultured in live or inactivated forms successively or simultaneously. The mycelial morphology and high-performance thin layer chromatography (HPTLC) including bioautography of the fermentation extracts were recorded. Furthermore, the agar cup-plate method was used to compare the antimicrobial activity of the extracts. Based on the above, liquid chromatography-photodiode array-tandem mass spectrometry (LC-PDA-MS/MS) together with Global Natural Products Social molecular networking (GNPS) and multiple natural products database mining were used to further analyze their secondary metabolite variations. The comprehensive results showed the following trends: (1) The strain first inoculated will strongly inhibit the growth and metabolism of the latter inoculated one; (2) Autoclaved A. unguis exerted a strong inducing effect on later inoculated A. terreus, while the autoclaved A. terreus showed high stability of its metabolites and still potently suppressed the growth and metabolism of A. unguis; (3) When the two strains are inoculated simultaneously, they both grow and produce metabolites; however, the A. terreus seemed to be more strongly induced by live A. unguis and this inducing effect surpassed that of the autoclaved A. unguis. Under some of the conditions, the extracts showed higher antimicrobial activity than the axenic cultures. Totally, A. unguis was negative in response but potent in stimulating its rival while A. terreus had the opposite effect. Fifteen MS detectable and/or UV active peaks showed different yields in co-cultures vs. the corresponding axenic culture. GNPS analysis assisted by multiple natural products databases mining (PubChem, Dictionary of Natural Products, NPASS, etc.) gave reasonable annotations for some of these peaks, including antimicrobial compounds such as unguisin A, lovastatin, and nidulin. However, some of the peaks were correlated with antagonistic properties and remain as possible novel compounds without mass or UV matching hits from any database. It is intriguing that the two strains both synthesize chemical ‘weapons’ for antagonism, and that these are upregulated when needed in competitive co-culture environment. At the same time, compounds not useful in this antagonistic setting are downregulated in their expression. Some of the natural products produced during antagonism are unknown chlorinated metabolites and deserve further study for their antimicrobial properties. In summary, this study disclosed the different responses of two Aspergillus strains in co-culture, revealed their metabolic variation, and displayed new opportunities for antibiotic discovery.

Evaluation of the antiproliferative effect of selected plant extracts on colon and skin cancer cell lines

Essential Oil Secondary Metabolites Variation of Salvia palaestina Leaves Growing wild from Different Locations in PalestineHatem Hejaz, Reem Sabbobeh, Hashem Al-Jaas, Ali Jahajha, Saleh Abu-Lafi

TLC-Based Fingerprinting Analysis of the Geographical Variation of Melastoma malabathricum in Inland and Archipelago Regions: A Rapid and Easy-to-Use Tool for Field Metabolomics Studies.

Melastoma malabathricum is an Indo-Pacific herb that has been used traditionally to treat numerous ailments such as wounds, dysentery, diarrhea, toothache, and diabetes. The objective of this study was to evaluate the variability of the metabolic profiles of M. malabathricum across its geographic distribution. By employing thin layer chromatography (TLC), specimens collected from six terrestrial and archipelago regions of Indonesia were analyzed by densitometry for metabolomic fingerprinting analysis combined with chemometric tools: principal component analysis (PCA) and hierarchical cluster analysis (HCA). Two PCAs were identified as PC1 and PC2 with 41.90% and 20.36%, respectively. Our results indicate the importance of considering geographic distribution during field-collection efforts since they demonstrate regional metabolic variation in secondary metabolites of M. malabathricum, as illustrated by TLC and their biological activities.

Profiling of Polyphenols and Glucosinolates in Kale and Broccoli Microgreens Grown under Chamber and Windowsill Conditions by Ultrahigh-Performance Liquid Chromatography High-Resolution Mass Spectrometry

Vegetables from the Brassica family are rich in many health-beneficial components, including high levels of polyphenols and glucosinolates (GSLs). However, their exact metabolite compositions are highly affected by cultivating and environmental conditions. Here, we provide the first report of polyphenol and GSL composition of kale and broccoli microgreens grown in growth chamber and windowsill environments. The samples were harvested 10 days after sowing and analyzed using ultrahigh-performance liquid chromatography high-resolution mass spectrometry. Principal component analysis was performed to visualize group clustering, trends, and discriminative ion features. Flavonol derivatives (21 in kale and 7 in broccoli) and hydroxycinnamic acid derivatives (14 in kale and 22 in broccoli) were identified under both growing conditions. Additionally, GSLs, including 7 in kale and 9 in broccoli, were detected. The results demonstrated a clear variation in secondary metabolites between the two growing conditions. The discriminative ion features were hydroxycinnamic acid esters of flavonols and indolic GSLs. Compared to chamber conditions, hydroxycinnamic acid esters of flavonols such as kaempferol-3-disinapoyl-triglucoside-7-diglucoside, kaempferol-3-disinpapoyl-triglucoside-7-glucoside, and kaempferol-3-disinpapoyl-diglucoside-7-glucoside were found to be greater in the windowsill-grown vegetables. The contents of 4-methoxyglucobrassicin and neoglucobrassicin, on the other hand, were greater in the chamber-grown ones. The results suggest that kale and broccoli microgreens grown under commercial- and in-home-grown conditions have different secondary metabolite compositions.

Study on enhanced extraction and seasonal variation of secondary metabolites in Eucommia ulmoides leaves using deep eutectic solvents

It has been considered as a crucial field for the extraction of active ingredients from herbal medicine to use a green and efficient method in the medicinal and food industries. In recent years, deep eutectic solvents (DESs) have been obtaining increase attention in green chemistry area since its sustainability, safety and biodegradability. In this study, an efficient DES composed of choline chloride and L-(+)-ascorbic acid with a molar ratio of 2:1 performed higher efficacy on the extraction of target compounds (including iridoids, phenolic acids and flavonoids) in Eucommia ulmoides leaves than 50% methanol solution. Considering the extraction efficacy and time consumption, microwave-assisted extraction (MAE) was selected and the operational conditions, including power of microwave, liquid/solid ratio and irradiation time were optimized by response surface methodology (RSM). Water was used as anti-solvent to recover ten target analytes from DES with recovery yields of 97.59%, 94.91%, 96.09%, 90.66%, 95.16%, 87.33%, 86.57%, 82.15%, 89.28% and 80.75% for eucommiol (EU), aucubin (AU), geniposidic acid (GA), chlorogenic acid (CA), asperuloside (AP), rutin (RU), kaempferol-3-O-sambubioside (KS), isoquercitrin (IQ), kaempferol-3-O-rutinoside (KR) and astragaline (AS), respectively. By combining the DES-based MAE and quantitative analysis of multi-components by single mark (QAMS) methods, the contents of ten compounds in the leaves of Eucommia ulmoides were determined to clarify the relationship between the accumulation of secondary metabolites and the harvest period. It was found that the contents of main ingredients reached the highest during May to October. The period appears to be the best harvest period for Eucommia ulmoides leaves. This study provides a novel strategy for the harvesting, processing, and quality control of the raw materials from Eucommia ulmoides leaves.

Characterization of secondary metabolites in kasturi mango (Mangifera casturi) using gas chromatography-mass spectrometry

Indonesia is a high biodiversity country for underutilized fruits. Indonesian underutilized fruits contain several beneficial functional foods that are very useful for human health. This study aimed to analyze the secondary metabolites found in Kasturi mango (Mangifera casturi). Fruit sampling was carried out in Hulu Sungai Selatan and Banjar, South Kalimantan. Five types of Kasturi mango were used, namely Kasturi, Pinari, Palipisan, Cuban, and Rawa-rawa, which included aril and rind. The results of this research showed that there are specific compounds in each type. Analysis of secondary metabolites using gas chromatography-mass spectrometry (GC-MS) in Kasturi aril showed that specific compounds were obtained in the Kasturi type, such as 13-tetradecenal ethyl elaidate, spinacene, and (23S)-ethylcholest-5-en-3.beta.-ol. The Rawa-rawa type contained specific compounds such as tetradecanoic acid and cis-vaccenic acid. Analysis of secondary metabolites with GC-MS in Kasturi rind showed that the Kasturi type contained specific compounds, such as distearil phosphite and 13-octadecenoic acid. The Rawa-rawa type contained specific compounds such as docosane and triacontyl acetate. Based on, characterization of secondary metabolites using GC-MS, Kasturi mango showed the high variation of secondary metabolites among their types.

Climate and Competitive Status Modulate the Variation in Secondary Metabolites More in Leaves Than in Fine Roots of Betula pendula.

Plant secondary metabolites have many important functions; they also determine the productivity and resilience of trees under climate change. The effects of environmental factors on secondary metabolites are much better understood in above-ground than in below-ground part of the tree. Competition is a crucial biotic stress factor, but little is known about the interaction effect of climate and competition on the secondary chemistry of trees. Moreover, competition effect is usually overlooked when analyzing the sources of variation in the secondary chemistry. Our aim was to clarify the effects of competitive status, within-crown light environment, and climate on the secondary chemistry of silver birch (Betula pendula Roth). We sampled leaves (from upper and lower crown) and fine roots from competitively dominant and suppressed B. pendula trees in plantations along a latitudinal gradient (56–67° N) in Fennoscandia, with mean annual temperature (MAT) range: −1 to 8°C. Secondary metabolites in leaves (SML) and fine roots (SMFR) were determined with an HPLC-qTOF mass spectrometer. We found that SML content increased significantly with MAT. The effect of competitive stress on SML strengthened in colder climates (MAT<4°C). Competition and shade initiated a few similar responses in SML. SMFR varied less with MAT. Suppressed trees allocated relatively more resources to SML in warmer climates and to SMFR in colder ones. Our study revealed that the content and profile of secondary metabolites (mostly phenolic defense compounds and growth regulators) in leaves of B. pendula varied with climate and reflected the trees’ defense requirements against herbivory, exposure to irradiance, and competitive status (resource supply). The metabolic profile of fine roots reflected, besides defense requirements, also different below-ground competition strategies in warmer and colder climates. An increase in carbon assimilation to secondary compounds can be expected at northern latitudes due to climate change.

Seasonal variation in defence compounds: A case study on pyrrolizidine alkaloids of clones of Jacobaea vulgaris, Jacobaea aquatica and their hybrids

Concentration of plant secondary metabolites (SMs) show seasonal variations. However, it is still not well understood how these abiotic and biotic factors influence the seasonal variations of SMs. In addition, it is of interest to know if and how SMs are reallocated to the different plant organs, in particular whether SMs are reallocated to the remaining tissues when biomass is lost, e.g., during winter. Here we used Jacobaea vulgaris, Jacobaea aquatica, two F1 and four F2 hybrids that differed in their pyrrolizidine alkaloids (PAs) bouquet as a study system. A series of clones of these genotypes were investigated during their vegetative stage spanning 14 months in a semi-natural environment. We found that the total PA concentration in roots and shoots showed a gradual increase until the spring of the second year, whereafter it dropped substantially in shoots. The variation in PA composition due to seasonal changes was significant but relatively small. Senecionine-like PAs were the dominant PAs in roots, while jacobine-/erucifoline-like PAs were dominant in shoots. The variation of PA concentration was significantly correlated with temperature, day length, and plant age. A correlation analysis showed that PAs were not reallocated when biomass was lost in winter. Overall, our study showed that PA composition of each genotype changed over seasons in a different manner but seasonal variation did not overrule the differences in PA composition among genotypes.

Variation of Chemical Components in Sapwood, Transition Zone, and Heartwood of Dalbergia odorifera and Its Relationship with Heartwood Formation

Heartwood has a high economic value because of its natural durability, beautiful color, special aroma, and richness in active ingredients used in traditional Chinese medicine. However, the mechanism of heartwood formation remains unclear. Dalbergia odorifera was selected as the object of research to analyze this variation in the chemical composition of sapwood, transition zone, and heartwood as well as to elucidate the relationship between this variation and the formation of heartwood. The variation of secondary metabolites was analyzed using gas chromatography-mass spectrometry and ultra-high performance liquid chromatography–mass spectrometry, the variation of lignin was analyzed using Fourier transform infrared spectroscopy and ultraviolet visible spectrophotometry, and the variation law of mineral elements was analyzed using atomic absorption spectrophotometry. The results demonstrated that contents of characteristic secondary metabolites in Dalbergia odorifera were mainly distributed in heartwood (84.3–96.8%), increased from the outer to inner layers of the xylem, and sudden changes occurred in the transition zone (the fourth growth ring). The Dalbergia odorifera lignin can be identified as typical “syringyl–guaiacyl (S–G)” lignin, and the color darkened from the outside to the inside. The results demonstrated that there were more benzene rings and conjugated C=O structures in the heartwood. Additionally, the variation of minerals in the xylem was related to elemental types; the average concentrations of Mg, Ca, Fe and Sr were higher in the heartwood than in the sapwood, whereas the concentrations of K and Zn were higher in the sapwood than in the heartwood owing to the reabsorption of elements. The concentrations of Na and Cu were similar in the heartwood and sapwood. The composition and structural characteristics of secondary metabolites, lignin, and mineral elements in the three typical xylem regions (sapwood, transition zone and heartwood) of Dalbergia odorifera changed. The most abrupt change occurred in the narrow xylem transition zone, which is the key location involved in heartwood formation in Dalbergia odorifera.