Biology subjects

Eilers, E. J.

Publications and source records attributed to Eilers, E. J..

5 recordsLinked to original sources

bioRxiv2023

Flower visitor groups show differential responses to individual and plot-level chemodiversity with consequences for plant fitness

O_LIChemodiversity, the diversity of specialised metabolites, plays a crucial role in mediating interactions between plants and animals, including insect herbivores and mutualists. Chemodiversity can be observed at both the individual and the population level. However, the impacts of chemodiversity at these two levels on interactions between plants and floral visitors, mainly pollinators and floral herbivores (florivores), are only poorly understood. C_LIO_LIThis study aimed to investigate the effects of chemodiversity at both individual and plot level on pollinators and florivores, examining their mutual interactions. To investigate these questions, we used individuals of the perennial Tanacetum vulgare differing in their terpenoid composition, representing so-called chemotypes. We planted individuals of five distinct chemotypes in a common garden design with homogeneous (five plants of the same chemotype) and heterogeneous (five different chemotypes) plots and observed flower visits in dependence of individual chemotype and plot type. Seeds were collected from a subset of plants and germination rates determined. C_LIO_LIOur findings revealed that chemodiversity at the plot level significantly influenced pollinator visitation, with more visits on plants of heterogeneous plots. We also observed marginally more pollinators on one of the chemotypes grown in homogeneous plots. In contrast, chemotype but not plot type had a significant effect on florivore visits. Pollinator and florivore species richness did not vary with plot type. Furthermore, a negative correlation was observed between pollinator and florivore visits in one year, suggesting competitive interactions between these two groups. Germination rates were positively correlated with pollinator visits and affected by chemotype but not by florivore visits or plot type. C_LIO_LISynthesis. Our study emphasizes the significance of the scale at which different chemical profiles are perceived by flower visitors, potentially influencing the reproductive fitness of plants. Exploring the ecology of these visitors and the varying selection pressures they exert on floral chemistry can help elucidating the evolutionary processes that maintain chemodiversity in natural environments. C_LI

ecology↗

bioRxiv2023

Chemodiversity in flowers of Tanacetum vulgare has consequences on a florivorous beetle

O_LIThe chemical composition of plant individuals can vary, leading to high intraspecific chemodiversity. Diversity of floral chemistry may impact the responses of flower-feeding insect visitors. C_LIO_LIPlants of Tanacetum vulgare vary significantly in their leaf terpenoid composition, resulting in distinct chemotypes. We investigated the composition of terpenoids and nutritents of flower heads and pollen in plants belonging to three chemotypes, dominated either by {beta}-thujone (BThu), artemisia ketone (Keto) or a mixture of (Z)-myroxide, santolina triene and artemisyl acetate (Myrox). Moreover, we tested the effects of these differences on preferences, weight gain and performance of adults of the shining flower beetle, Olibrus aeneus. C_LIO_LIThe terpenoid composition and diversity of flower heads and pollen significantly differed among individuals belonging to these chemotypes, while total concentrations of terpenoids, sugars, amino acids or lipids of the pollen did not differ. Beetles preferred the BThu over the Myrox chemotype in both olfactory and contact choice assays, while the Keto chemotype was marginally repellent in olfactory assays. The beetles gained the least weight within 48 h and their initial mortality was highest when feeding exclusively on floral tissues of the Myrox chemotype. Short-term weight gain and long-term performance were highest on the BThu chemotype. C_LIO_LIIn conclusion, the beetles showed chemotype-specific responses towards different T. vulgare chemotypes, which may be attributed to the terpenoid composition in flower heads and pollen rather than to differences in nutrient profiles. Both richness and overall diversity are important factors when determining chemodiversity of individual plants and their consequences on interacting insects. C_LI SHORT SUMMARYWe demonstrate that Tanacetum vulgare chemotypes distinguished by their leaf terpenoid profiles also show unique floral and pollen chemotypes based on terpenoid composition and diversity, which affect the preference and performance of a beetle florivore.

ecology↗

bioRxiv2023

Inter-laboratory comparison of plant volatile analyses in the light of intra-specific chemodiversity

IntroductionAssessing intraspecific variation in plant volatile organic compounds (VOCs) involves pitfalls that may bias biological interpretation, particularly when several laboratories collaborate on joint projects. Comparative, inter-laboratory ring trials can inform on the reproducibility of such analyses. ObjectivesIn a ring trial involving five laboratories, we investigated the reproducibility of VOC collections with polydimethylsiloxane (PDMS) and analyses by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). As model plant we used Tanacetum vulgare, which shows a remarkable diversity in terpenoids, forming so-called chemotypes. We performed our ring-trial with two chemotypes to examine the sources of technical variation in plant VOC measurements during pre-analytical, analytical, and post-analytical steps. MethodsMonoclonal root cuttings were generated in one laboratory and distributed to five laboratories, in which plants were grown under laboratory-specific conditions. VOCs were collected on PDMS tubes from all plants before and after a jasmonic acid (JA) treatment. Thereafter, each laboratory (donors) sent a subset of tubes to four of the other laboratories (recipients), which performed TD-GC-MS with their own established procedures. ResultsChemotype-specific differences in VOC profiles were detected but with an overall high variation both across donor and recipient laboratories. JA-induced changes in VOC profiles were not reproducible. Laboratory-specific growth conditions led to phenotypic variation that affected the resulting VOC profiles. ConclusionOur ring trial shows that despite large efforts to standardise each VOC measurement step, the outcomes differed both qualitatively and quantitatively. Our results reveal sources of variation in plant VOC research and may help to avoid systematic errors in similar experiments.

plant biology↗

bioRxiv2023

Influences of chemotype and parental genotype on metabolic fingerprints of tansy plants uncovered by predictive metabolomics.

Intraspecific plant chemodiversity shapes plant-environment interactions. Within species, chemotypes can be defined according to variation in dominant specialised metabolites belonging to certain classes. Different ecological functions could be assigned to these distinct chemotypes. However, the roles of other metabolic variations and the parental genotype of the chemotypes remain poorly explored. Here, we first compared the capacity of terpenoid profiles and metabolic fingerprints to distinguish five chemotypes of common tansy (Tanacetum vulgare) and depict satellite metabolic differences. Metabolic fingerprints captured higher satellite variation while preserving the ability to define chemotypes. These satellite differences might influence plant performance and interactions with the environment. Next, to characterise the influence of the maternal genotype on chemodiversity, we performed variation partitioning and generalised linear modelling. Our findings revealed that maternal genotype was a higher source of chemical variation than chemotype. Predictive metabolomics unveiled 184 markers predicting maternal genotype with 89% accuracy. These markers included, among others, phenolics, whose functions in plant-environment interactions are well established. Hence, these findings place parental genotype at the forefront of intraspecific chemodiversity. We thus recommend considering this factor when comparing the ecology of various chemotypes. Besides, the combined inclusion of inherited and satellite metabolic variation in computational models may help connecting chemodiversity and evolutionary principles.

ecology↗

bioRxiv2023

Floral volatiles evoke partially similar responses in both florivores and pollinators and are correlated with non-volatile reward chemicals

BackgroundPlants use floral displays to attract mutualists, but simultaneously need to prevent attacks by antagonists. Chemical displays detectable from a distance include attractive or repellent floral volatile organic compounds (FVOCs). Post-landing, visitors perceive contact chemicals including nutrients, but also deterrent or toxic constituents in pollen and nectar, protecting flowers from overexploitation. The composition of FVOCs and pollen chemistry is well known to vary among and within species. However, we lack knowledge about differences and similarities in the detectability of and behavioural responses towards these compounds for insect flower visitor groups of key importance, i.e., mutualistic pollinators versus antagonistic florivores, as well as the correlation between FVOCs and pollen chemodiversity. ScopeWe reviewed how FVOCs and non-volatile floral chemical displays, i.e., nutrients and toxins of pollen, vary in composition and how they affect the detection and behaviour of insect flower visitors. Moreover, we used a meta-analytic approach to evaluate the detection of and responses towards FVOCs by pollinators vs. florivores within the same plant genera. Furthermore, we tested whether the chemodiversity of FVOCs as well as nutrients and toxins stored in pollen are correlated and hence informative about each other. Key ResultsAccording to the available data, florivores are more likely to detect FVOCs than pollinators. Common FVOCs such as linalool and methyl salicylate were often reported as attractive to pollinators and repellent towards florivores. A higher number of FVOCs was found to be attractive to both mutualists and antagonists compared to shared repellent compounds. Furthermore, a negative correlation between FVOC richness and the number of pollen toxin classes was revealed, besides a trend towards a positive correlation between pollen protein amount and the number of pollen toxins. ConclusionsPlants face critical trade-offs when producing floral chemicals, as these partly mediate the same information, particularly attraction but also repellence or toxicity, to both mutualists and antagonists. Moreover, chemodiversity of different floral parts is partly correlated and thus highly relevant for investigations of flower-insect interactions. Further research is needed on more different wild and cultivated plant species and mutualistic and antagonistic interaction partners to test for generalisation of these patterns.

ecology↗