Plant Chemistry Research Articles

Unpacking IPCC and IPBES Reports

Humanity is facing a set of existential challenges, including the handling of the parallel and interconnected crises of climate change and biodiversity loss. In an effort to address these challenges, international bodies like the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) have been created. These bodies are producing a series of reports that compile scientific information on specific aspects of climate and biodiversity research and discuss policy options and other social implications. So far, these reports have been provided in formats that make it hard to mobilize the knowledge encapsulated in them. Our contribution demonstrates technical workflows for achieving such mobilization by mining the reports. Development of these workflows is spearheaded by young researchers from the SemanticClimate team of interns based at the National Institute of Plant Genome Research (NIPGR) in New Delhi, India, and volunteers from all over the world. The tool chain includes methods for cleaning up the formatting, for extracting and processing raw text, tables and figures and annotating them semantically with the help of controlled vocabularies, ontologies and Wikidata. The semantic information and the mined information can then be combined in a way that iteratively improves both, eventually resulting in versions of the reports wherein entities like species, countries or references are semantically marked up and rendered in responsive formats. Our framework supports multilingual and specialist interests (e.g., endangered species, plant chemistry), and we will also briefly discuss how the use of standard open licensing could further contribute to mobilizing information from the reports. We are keen to work with other groups sharing these interests as well as with the teams involved in producing the reports.

Abiotic stress rather than biotic interactions drives contrasting trends in chemical richness and variation in alpine willows

Abstract Plants produce an astonishing diversity of specialized metabolites as defences against herbivores, pathogens or detrimental abiotic conditions. Plants growing at different elevations are exposed to different biotic and abiotic conditions and typically show pronounced differences in their chemistry. Understanding how these differences arise through changes in various measures of chemical diversity can inform us concerning factors that contribute to the variety of metabolites found among plants. We focused on elevational changes in concentration, richness and intra‐ and interspecific variation in specialized chemistry in willows (Salix, Salicaceae) and compare them among metabolite classes with different functions. We aim to show how these various measures of chemical diversity change with elevation to reveal trends contributing to changes in plant chemistry along major ecological gradients. We studied chemistry, herbivory and fungal pathogen damage in an assemblage of seven willow species along an elevational gradient in the Alps (800–2600 m a.s.l.). We examined trends in chemical diversity using untargeted metabolomics, and further quantified trends in three specific classes: proanthocyanidins and salicinoids involved in biotic interactions, and flavonoids involved mainly in abiotic protection. We use measures of willow chemistry that take structural relatedness of metabolites into account to show if the roles of structurally distinct metabolites change with elevation. Willows from low elevations exhibited greater proanthocyanidin concentration and structural richness of flavonoids. In contrast, willows from high elevations showed greater structural richness of salicinoids and greater variation in total metabolite composition at both the intra‐ and interspecific levels. The trends in salicinoid richness and proanthocyanidin concentration were explained by elevational changes in temperature. Our results show how elevational differences in plant chemistry arise through trends in various aspects of their chemical diversity. Willows at high elevations showed reduced structural richness of metabolites involved in abiotic protection. This may reflect focused investment in metabolites with the highest ecological benefit relative to their concentration in high‐elevation willows. At the same time, they possessed greater richness of metabolites involved in biotic interactions, while variation in microhabitat preferences among high‐elevation species likely contributed to the high variation in their total metabolite pool. Read the free Plain Language Summary for this article on the Journal blog.

Specialised chemistry affects insect abundance but not overall community similarity in three rare shrub willows: Salix myrtilloides, S. repens and S. rosmarinifolia

Willows serve as a keystone host-plant genus for insect herbivores. The diversity of insect herbivore assemblages harboured by willows is typically affected by the diversity of specialised metabolites that willows produce. Here, we studied three small, shrubby willow species (Salix myrtilloides, S. repens and S. rosmarinifolia) that primarily occur at sites of high conservation value in the Czech Republic. We explored if associated insect communities reflect the specialised chemistry in these uncommon host plants. We measured the three willow species for overall metabolomic profiles and salicinoids using non-targeted metabolomics and sampled them for caterpillars, leaf-chewing beetles (adults and larvae), sawfly larvae, and sap-sucking Hemiptera. We detected 2,067 metabolites across the three willow species. Most of them were shared by S. repens and S. rosmarinifolia, while S. myrtilloides showed a distinct chemical profile. Salix repens and S. rosmarinifolia also had significantly higher concentration and richness of salicinoids than S. myrtilloides. The abundance of all insect species and generalists that also feed on host-plants outside Salicaceae was higher on S. myrtilloides than on S. rosmarinifolia or S. repens. The abundance of Salicaceae specialists did not differ among the three willow species. Insect community composition, in contrast, did not show pronounced differences among the three willows. Our results suggest that salicinoids may be responsible for the low abundance of generalist herbivores. Furthermore, our study indicates that herbivore community composition does not reflect the specialised chemistry in the three willows we studied. Therefore, we hypothesise that the presence of some of the insect species is primarily determined by other factors, such as the habitat type where the respective willow species occur. Although the studied willows possess some characteristic specialised chemistry, we conclude that their importance as hosts of specific and sometimes threatened insect fauna may be mediated by willow habitat preference.

Oviposition stimulants underlying different preferences between host races in the leaf-mining moth Acrocercops transecta (Lepidoptera: Gracillariidae)

The importance of plant chemistry in the host specialization of phytophagous insects has been emphasized. However, only a few chemicals associated with host shifting have been characterized. Herein, we focus on the leaf-mining moth Acrocercops transecta (Gracillariidae) consisting of ancestral Juglans (Juglandaceae)- and derived Lyonia (Ericaceae)-associated host races. The females of the Lyonia race laid eggs on a cover glass treated with an L. ovalifolia leaf extract; the extract was fractionated using silica gel and ODS column chromatography to isolate the oviposition stimulants. From a separated fraction, two analogous Lyonia-specific triterpenoid glycosides were characterized as oviposition stimulants. Furthermore, we observed probable contact chemosensilla on the distal portion of the female antennae. Lyonia race females laid their eggs on the non-host Juglans after the leaves were treated with a Lyonia-specific oviposition stimulant, although they do not lay eggs on Juglans. These results suggest that Lyonia race females do not lay eggs on Juglans leaves because the leaves do not contain specific oviposition stimulant(s). Otherwise, the activity of the oviposition stimulants overcomes oviposition deterrents contained in Juglans leaves. This paper describes the roles of plant chemicals in the different preferences between host races associated with distantly related plant taxa.

Development of a polyphagous leaf beetle on different host plant species and its detoxification of glucosinolates

Herbivores face a broad range of defences when feeding on plants. By mixing diets, polyphagous herbivores are assumed to benefit during their development by gaining a better nutritional balance and reducing the intake of toxic compounds from individual plant species. Nevertheless, they also show strategies to metabolically cope with plant defences. In this study, we investigated the development of the polyphagous tansy leaf beetle, Galeruca tanaceti (Coleoptera: Chrysomelidae), on mono diets consisting of one plant species [cabbage (Brassica rapa), Brassicaceae; lettuce (Lactuca sativa), or tansy (Tanacetum vulgare), Asteraceae] vs. two mixed diets, both containing tansy. Leaves of the three species were analysed for contents of water, carbon and nitrogen, the specific leaf area (SLA) and trichome density. Furthermore, we studied the insect metabolism of two glucosinolates, characteristic defences of Brassicaceae. Individuals reared on cabbage mono diet developed fastest and showed the highest survival, while the development was slowest for individuals kept on tansy mono diet. Lettuce had the highest water content and SLA but the lowest C/N ratio and no trichomes. In contrast, tansy had the lowest water content and SLA but the highest C/N ratio and trichome density. Cabbage was intermediate in these traits. Analysis of insect samples with UHPLC-DAD-QTOF-MS/MS revealed that benzyl glucosinolate was metabolised to N-benzoylglycine, N-benzoylalanine and N-benzoylserine. MALDI-Orbitrap-MS imaging revealed the localisation of these metabolites in the larval hindgut region. 4-Hydroxybenzyl glucosinolate was metabolised to N-(4-hydroxybenzoyl)glycine. Our results highlight that G. tanaceti deals with toxic hydrolysis products of glucosinolates by conjugation with different amino acids, which may enable this species to develop well on cabbage. The high trichome density and/or specific plant chemistry may lower the accessibility and/or digestibility of tansy leaves, leading to a poorer beetle development on pure tansy diet or diet mixes containing tansy. Thus, diet mixing is not necessarily beneficial, if one of the plant species is strongly defended.

Exploring Relationships among Grapevine Chemical and Physiological Parameters and Leaf and Berry Mycobiome Composition.

Improving our knowledge on biotic and abiotic factors that influence the composition of the grapevine mycobiome is of great agricultural significance, due to potential effects on plant health, productivity, and wine characteristics. Here, we assessed the influence of scion cultivar on the diversity and composition of fungal communities in the berries and leaves of three different cultivars. We generated DNA metabarcoding data, and statistically compared the richness, relative abundance, and composition of several functional groups of fungi among cultivars, which are partly explained by measured differences in chemical composition of leaves and berries and physiological traits of leaves. Fungal communities in leaves and berries show contrasting patterns among cultivars. The richness and relative abundance of fungal functional groups statistically differ among berry and leaf samples, but less so among cultivars. Community composition of the dominant functional groups of fungi, i.e., plant pathogens in leaves and saprotrophs in berries, differs significantly among cultivars. We also detect cultivar-level differences in the macro- and microelement content of the leaves, and in acidity and sugar concentration of berries. Our findings suggest that there appears to be a relatively diverse set of fungi that make up the grapevine mycobiome at the sampled terroir that spans several cultivars, and that both berry and leaf mycobiomes are likely influenced by the chemical characteristics of berries and leaves, e.g., pH and the availability of nutrients and simple carbohydrates. Finally, the correlation between fungal community composition and physiological variables in leaves is noteworthy, and merits further research to explore causality. Our findings offer novel insights into the microbial dynamics of grapevine considering plant chemistry and physiology, with implications for viticulture.

Near infrared spectroscopy calibration strategies to predict multiple nutritional parameters of pasture species from different functional groups

Near infrared reflectance (NIR) spectroscopy has been used by the agricultural industry as a rapid and inexpensive technique to quantify nutritional chemistry in plants. The aim of this study was to evaluate the performance of NIR calibrations in predicting the nutritional composition of ten pasture species that underpin livestock industries in many countries. The species comprised a range of functional diversity (C3 legumes; C3/C4 grasses; annuals/perennials) and origins (tropical/temperate; introduced/native) that grew under varied environmental conditions (control and experimentally induced warming and drought) over a period of more than two years ( n = 2622). A maximal calibration set including 391 samples was used to develop and evaluate calibrations for all ten pasture species (global calibrations), as well as for subsets comprised of the plant functional groups. This study found that the global calibrations were appropriate to predict the six key nutritional quality parameters for the studied pasture species, with the highest estimation quality found for ash (ASH), crude protein (CP), amylase-treated neutral detergent fibre (aNDF) and acid detergent fibre (ADF), and the lowest for ether extract (EE) and acid detergent lignin (ADL) parameters. The plant functional group calibrations for C3 grasses performed better than the global calibrations for ASH, CP, ADF and EE parameters, whereas for C3 legumes and C4 grasses the functional group calibrations performed less well than the global calibrations for all nutritional parameters of these groups. Additionally, the calibrations were able to capture the range of variation in forage nutritional quality caused by future climate scenarios of warming and severe drought.

Cambisol Mycobiome in a Long-Term Field Experiment with Korean Pine as a Sole Edificator: A Case Study

A culture-independent mycobiome survey in Haplic Cambisol under Korean pine in a long-term field experiment in the Russian Far East was conducted using sequence analysis of the ITS region amplified with ITS3/ITS4 primers using the metagenomic DNA as a matrix. Overall 758 fungal OTUs were identified, representing 15 phyla, 47 classes, 104 orders, 183 families, and 258 genera. More OTUs represented the Ascomycota phylum (513) than Basidiomycota (113), with both phyla together comprising 95% of the relative abundance. The Leotiomycetes class was ultimately prevailing; apparently contributing significantly to the organic matter decomposition and microbial biomass in soil, as shown by a PCA. Only two dominant OTUs (Pseudogymnoascus sp. and Hyaloscyphaceae, both Ascomycota) were common in the studied samples. The presented high mycobiome diversity in soil under the monospecies artificial forest, where Korean pine had been the sole edificator for forty years, allows concluding that plant chemistry diversity is the main factor shaping the soil mycobiome in such an environment. The obtained data provide a reference for further studies of soil mycobiota, especially under Korean pine with its aesthetic, as well as nut-producing, potential. The results can be helpful in the targeted creating of a soil mycobiome beneficial for pines in afforestation and remediation contexts.

The chemical ecology of tropical forest diversity: Environmental variation, chemical similarity, herbivory, and richness.

Species richness in tropical forests is correlated with other dimensions of diversity, including the diversity of plant-herbivore interactions and the phytochemical diversity that influences those interactions. Understanding the complexity of plant chemistry and the importance of phytochemical diversity for plant-insect interactions and overall forest richness has been enhanced significantly by the application of metabolomics to natural systems. The present work used proton nuclear magnetic resonance spectroscopy (1 H-NMR) profiling of crude leaf extracts to study phytochemical similarity and diversity among Piper plants growing naturally in the Atlantic Rainforest of Brazil. Spectral profile similarity and chemical diversity were quantified to examine the relationship between metrics of phytochemical diversity, specialist and generalist herbivory, and understory plant richness. Herbivory increased with understory species richness, while generalist herbivory increased and specialist herbivory decreased with the diversity of Piper leaf material available. Specialist herbivory increased when conspecific host plants were more spectroscopically dissimilar. Spectral similarity was lower among individuals of common species, and they were also more spectrally diverse, indicating phytochemical diversity is beneficial to plants. Canopy openness and soil nutrients also influenced chemistry and herbivory. The complex relationships uncovered in this study add information to our growing understanding of the importance of phytochemical diversity for plant-insect interactions and tropical plant species richness.

Advances in Plant Chemistry and Pharmacology of Vitex

Advances in Plant Chemistry and Pharmacology of Vitex

Flavonoid-producing tomato plants have a direct negative effect on the zoophytophagous biological control agent Orius sauteri.

Orius sauteri (Poppius) (Hemiptera: Anthocoridae) is often used for biological control of small arthropod pests in greenhouse vegetable production systems in Asia. In addition to feeding on arthropod prey, O. sauteri consumes small quantities of plant material. Previous studies demonstrated that tomato plant chemistry confers antixenosis resistance to phloem-feeding whiteflies, but the potential nontarget effects of phytochemicals on the beneficial predator O. sauteri are unknown. Comparison of O. sauteri confined to near-isogenic lines (NILs) of tomatoes producing high levels of flavonoids (NIL-purple hypocotyl; resistant to whiteflies) and low levels of flavonoids (NIL-green hypocotyl; susceptible to whiteflies) revealed that O. sauteri had reduced oviposition, nymphal survival, and development on resistant plants, even if they were also provided with prey that did not feed on the host plant. Moreover, O. sauteri showed a significant ovipositional preference in choice assays, laying significantly more eggs on susceptible than on resistant plants. Molecular gut content analysis using the specific chloroplast trnL gene from tomato confirmed that adult and immature O. sauteri feed on both resistant and susceptible genotypes, and feeding behavior assays revealed that resistance did not affect plant feeding or prey acceptance by O. sauteri adults. These results demonstrate a direct negative effect of phytochemicals on a nontarget beneficial species and indicate that resistance mediated by phytochemicals can affect organisms that do not solely feed on phloem sap. The results also indicate that the mode of action and the potential ecological effects of phytochemical-mediated resistance are broader than previously recognized.

Correlations Between the Metabolome and the Endophytic Fungal Metagenome Suggests Importance of Various Metabolite Classes in Community Assembly in Horseradish (Armoracia rusticana, Brassicaceae) Roots

The plant microbiome is an increasingly intensive research area, with significance in agriculture, general plant health, and production of bioactive natural products. Correlations between the fungal endophytic communities and plant chemistry can provide insight into these interactions, and suggest key contributors on both the chemical and fungal side. In this study, roots of various horseradish (Armoracia rusticana) accessions grown under the same conditions were sampled in two consecutive years and chemically characterized using a quality controlled, untargeted metabolomics approach by LC-ESI-MS/MS. Sinigrin, gluconasturtiin, glucoiberin, and glucobrassicin were also quantified. Thereafter, a subset of roots from eight accessions (n = 64) with considerable chemical variability was assessed for their endophytic fungal community, using an ITS2 amplicon-based metagenomic approach using a custom primer with high coverage on fungi, but no amplification of host internal transcribed spacer (ITS). A set of 335 chemical features, including putatively identified flavonoids, phospholipids, peptides, amino acid derivatives, indolic phytoalexins, a glucosinolate, and a glucosinolate downstream product was detected. Major taxa in horseradish roots belonged to Cantharellales, Glomerellales, Hypocreales, Pleosporales, Saccharomycetales, and Sordariales. Most abundant genera included typical endophytes such as Plectosphaerella, Thanatephorus, Podospora, Monosporascus, Exophiala, and Setophoma. A surprising dominance of single taxa was observed for many samples. In summary, 35.23% of reads of the plant endophytic fungal microbiome correlated with changes in the plant metabolome. While the concentration of flavonoid kaempferol glycosides positively correlated with the abundance of many fungal strains, many compounds showed negative correlations with fungi including indolic phytoalexins, a putative glucosinolate but not major glucosinolates and a glutathione isothiocyanate adduct. The latter is likely an in vivo glucosinolate decomposition product important in fungal arrest. Our results show the potency of the untargeted metabolomics approach in deciphering plant–microbe interactions and depicts a complex array of various metabolite classes in shaping the endophytic fungal community.

Recent Advancements in Green Synthesis of Nanoparticles for Improvement of Bioactivities: A Review.

Natural products have widely been used in applications ranging from antibacterial, antiviral, antifungal, and various other medicinal applications. The use of these natural products was recognized way before the establishment of basic chemistry behind the disease and the chemistry of plant metabo-lites. After the establishment of plant chemistry, various new horizons evolved, and the application of natural products breached the orthodox limitations. In one such interdisciplinary area, the use of plant materials in the synthesis of nanoparticles (NPs) has exponentially emerged. This advancement has offered various environment-friendly methods where hazardous chemicals are completely replaced by natural products in the sophisticated and hectic synthesis processes. This review is an attempt to under-stand the mechanism of metal nanoparticles synthesis using plant materials. It includes details on the role of the plant's secondary metabolites in the synthesis of nanoparticles including the mechanism of action. In addition, the use of these nanomaterials has widely been discussed along with the possible mechanism behind their antimicrobial and catalytic action.

Elemental Relationships in the Wood of Four Siberian Conifers: Whether Elements Are an Occasional Mixture

In the abundant literature on plant chemistry, little attention is paid to correlations among chemical elements in tissues. The goal of the research is to establish consistent correlations among elements in the xylem of four widespread Siberian conifers. X-ray fluorescent analysis has been applied to find out the elements contained in the xylem. The method allowed finding the mean count rates of Al, P, S, K, Ca, Ti, Mn, Fe, Cu, Zn, and Sr in trunks of trees. Moreover, the xylem samples were chemically treated twice, first in alcohol and then in HCl. It was found that species factor exerts a significant influence on the elemental content of a few elements, but not on all of them. The chemical treatment decreases the impact of the species factor. The treatment increases the number of significant correlations and strength of them. In some cases (especially with Al), the correlations may change the sign of the relationship. The consistent correlations may help arrange more profound chemical research revealing the forms in which the elements exist in xylem.

The co-existence of multiple oak leaf flushes contributes to the large within-tree variation in chemistry, insect attack and pathogen infection.

Summary Many plant species produce multiple leaf flushes during the growing season, which might have major consequences for within‐plant variation in chemistry and species interactions. Yet, we lack a theoretical or empirical framework for how differences among leaf flushes might shape variation in damage by insects and diseases.We assessed the impact of leaf flush identity on leaf chemistry, insect attack and pathogen infection on the pedunculate oak Quercus robur by sampling leaves from each leaf flush in 20 populations across seven European countries during an entire growing season.The first leaf flush had higher levels of primary compounds, and lower levels of secondary compounds, than the second flush, whereas plant chemistry was highly variable in the third flush. Insect attack decreased from the first to the third flush, whereas infection by oak powdery mildew was lowest on leaves from the first flush. The relationship between plant chemistry, insect attack and pathogen infection varied strongly among leaf flushes and seasons.Our findings demonstrate the importance of considering differences among leaf flushes for our understanding of within‐tree variation in chemistry, insect attack and disease levels, something particularly relevant given the expected increase in the number of leaf flushes with climate change.

A Perspective on Plant Phenomics: Coupling Deep Learning and Near-Infrared Spectroscopy.

The trait-based approach in plant ecology aims at understanding and classifying the diversity of ecological strategies by comparing plant morphology and physiology across organisms. The major drawback of the approach is that the time and financial cost of measuring the traits on many individuals and environments can be prohibitive. We show that combining near-infrared spectroscopy (NIRS) with deep learning resolves this limitation by quickly, non-destructively, and accurately measuring a suite of traits, including plant morphology, chemistry, and metabolism. Such an approach also allows to position plants within the well-known CSR triangle that depicts the diversity of plant ecological strategies. The processing of NIRS through deep learning identifies the effect of growth conditions on trait values, an issue that plagues traditional statistical approaches. Together, the coupling of NIRS and deep learning is a promising high-throughput approach to capture a range of ecological information on plant diversity and functioning and can accelerate the creation of extensive trait databases.

Practical teaching of pathophysiology to LAFFH at the IPD outpatient clinic of FMP/FASE: Historical Report

Background: Undergraduate students of UNIFASE/FMP, through the Academic League of Human Physiology and Pathophysiology (Liga Acadêmica de Fisiologia e Fisiopatologia Humana - LAFFH), participate in a supervised internship to outpatient at the Infectious and Parasitic Diseases Service of FMP/FASE, authorized by Clinical Direction (October 2018). Patients received conventional therapy in addition to complementary therapy with Homeopathy, for external use for cleaning skin lesions and modulating inflammatory responses, whose mechanisms of action are already described in the scientific literature and authorized by ANVISA. Aims: Make approach of undergraduate students to Homeopathic pathophysiology. Methodology: The supervised clinical internship of LAFFH students is in two service rooms with 6 students in each, based on prior appointment due to spontaneous demand, with medical records registered by the IPD outpatient service secretary. Outpatient clinical care addresses the pathophysiology and miasms of the symptoms and signs of neglected chronic parasitic diseases prevalent in our country, identified by anamnesis and physical examination. They are correlated to biological activities in plant chemistry classes, besides official homeopathic pharmacopoeia. So, it was adopted the external use of HUD Ledum palustre 6ch for the cleansing of skin lesions with torpid evolution at IPD. Results and discussion: Two patients with edema and varicose ulcers were treated with the ointment offered. Edema extension which was +++/4+ to both patients diminished to +/4+ in 30 days of interval. Indeed, ulcers remained at the same shape and size, but their bases were cleaned, without purulence. Novel clinical sessions did not occur because of social distancing needed. Conclusion: It has been developed a positive perception among patients and students about the action of homeopathic remedies. The practical teaching activity initiated encourages students in clinical reasoning about complementary therapeutic association with Homeopathy for patients whose evolution is below the expected prognosis with conventional therapy. Project of clinical observation will be elaborated to research ethics committee.

Arbuscular mycorrhizal fungi mediate how plant herbivory history influences herbivore performance

Abstract Herbivore performance is influenced by plant host quality and chemical defences, both of which are influenced by belowground symbionts of plants and herbivory history. The previous herbivory may suppress or facilitate subsequent herbivore performance through changes in plant chemistry and tissue quality. Likewise, arbuscular mycorrhizal fungi (AM fungi) can alter both plant quality and plant responses to aboveground herbivory, as mycorrhizal‐mediated alterations of the nutritional budget may alter leaf nutritional quality, chemical profiles, and available leaf surface area. Despite evidence that both herbivory history and AM fungi can independently affect herbivore performance, few studies directly test both at the same time. Here, the role of AM fungi and herbivory history on the performance of a pest insect (Spodoptera frugiperda) on a common forb (Solidago altissima) grown with different AM fungal additions (no AM fungi, single species, multispecies) was directly tested. Evidence that the effect of herbivory history on herbivore performance depended on the AM fungal environment of the plant was found. Specifically, the composition of the AM fungal additions altered the directionality of herbivore performance on plants with and without prior herbivory. Without added AM fungi, herbivores demonstrated a classically suppressed growth rate on grazed plants. With a single species AM fungi added, herbivores performed the same on host plants, regardless of herbivory history. With diverse AM fungi added, herbivore growth increased on grazed plants. Mycorrhizal‐mediated changes in plant chemical profiles did not explain herbivore performance. These results emphasise the need for direct tests of mycorrhizal diversity on plant‐insect interactions.

Natural processes influencing pollinator health.

Evidence from the last few decades indicates that pollinator abundance and diversity are at risk, with many species in decline. Anthropogenic impacts have been the focus of much recent work on the causes of these declines. However, natural processes, from plant chemistry, nutrition and microbial associations to landscape and habitat change, can also profoundly influence pollinator health. Here, we argue that these natural processes require greater attention and may even provide solutions to the deteriorating outlook for pollinators. Existing studies also focus on the decline of individuals and colonies and only occasionally at population levels. In the light of this we redefine pollinator health and argue that a top-down approach is required focusing at the ecological level of communities. We use examples from the primary research, opinion and review articles published in this special issue to illustrate how natural processes influence pollinator health, from community to individuals, and highlight where some of these processes could mitigate the challenges of anthropogenic and natural drivers of change.This article is part of the theme issue ‘Natural processes influencing pollinator health: from chemistry to landscapes’.

Phytochemical Screening, In vitro Antioxidant and Enzyme Inhibitory Properties, and Acute Toxicity of Extracts from the Aerial Parts of Ephedra nebrodensis, a Source of Bioactive Compounds.

Due to the strong association between the chemistry of medicinal plants and their biological properties, it is important to determine their phytochemical composition to justify experimental tests. The aim of this study was to evaluate the in vitro antioxidant and the enzyme inhibitory properties and to identify the bioactive compounds present in the extracts of Ephedra nebrodensis growing in Algeria. Total phenolic and flavonoids content in these extracts were quantified by Folin- Ciocalteu and aluminum chloride methods. The antioxidant capacity was assessed using DPPH, ABTS, β-carotene/linoleic acid, CUPRAC and FRAP assays, and in vitro cholinesterase activity against acetylcholinesterase and butyrylcholinesterase were evaluated. The chemical constituents of the extracts were analyzed by high-performance liquid chromatography coupled with mass spectrometric detection and gas chromatography. For the acute toxicity study, extracts were administered to mice at single dose of 2 g/kg and 5 g/kg by gavage. Plant extracts were rich in phenolic compounds. Ethyl acetate extract presented the highest phenolic (238.44 ± 1.50 μg GAE /mg of extract) and flavonoid (21.12 ± 0.00 μg QE /mg of extract) contents. Likewise, ethyl acetate extract showed potent radical scavenging and reducing properties. Ethanol-acetone extract showed inhibitory activity against acetylcholinesterase, and was a potent inhibitor of butyrylcholinesterase. In all extracts, flavonoids were the most abundant compounds. The phytochemical investigation showed the presence of alkaloids (ephedrine and pseudo-ephedrine). In the acute toxicity, the LD50 was superior to 5 g/kg body weight. There were no alterations in the histology of the liver and kidneys. This study demonstrated a good antioxidant potential and anticholinesterase activity of aerial parts of E. nebrodensis.