Ambient temperature influences tolerance to plant secondary compounds in a mammalian herbivore.
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ABSTRACT:
SUBMITTER: Kurnath P
PROVIDER: S-EPMC4721095 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Most herbivorous insect species are restricted to a narrow taxonomic range of host plant species. Herbivore species that feed on mustard plants and their relatives in the Brassicales have evolved highly efficient detoxification mechanisms that actually prevent toxic mustard oils from forming in the bodies of the animals. However, these mechanisms likely were not present during the initial stages of specialization on mustard plants ~100 million years ago. The herbivorous fly Scaptomyza nigrita (Drosophilidae) is a specialist on a single mustard species, bittercress (Cardamine cordifolia; Brassicaceae) and is in a fly lineage that evolved to feed on mustards only in the past 10-20 million years. In contrast to many mustard specialists, S. nigrita does not prevent formation of toxic breakdown products (mustard oils) arising from glucosinolates (GLS), the primary defensive compounds in mustard plants. Therefore, it is an appealing model for dissecting the early stages of host specialization. Because mustard oils actually form in the bodies of S. nigrita, we hypothesized that in lieu of a specialized detoxification mechanism, S. nigrita may mitigate exposure to high GLS levels within plant tissues using behavioral avoidance. Here, we report that jasmonic acid (JA) treatment increased GLS biosynthesis in bittercress, repelled adult female flies, and reduced larval growth. S. nigrita larval damage also induced foliar GLS, especially in apical leaves, which correspondingly displayed the least S. nigrita damage in controlled feeding trials and field surveys. Paradoxically, flies preferred to feed and oviposit on GLS-producing Arabidopsis thaliana despite larvae performing worse in these plants versus non-GLS-producing mutants. GLS may be feeding cues for S. nigrita despite their deterrent and defensive properties, which underscores the diverse relationship a mustard specialist has with its host when lacking a specialized means of mustard oil detoxification.
| S-EPMC4829532 | biostudies-literature
Project description:Extensive land-use change in the tropics has produced a mosaic of successional forests within an agricultural and cattle-pasture matrix. Post-disturbance biodiversity assessments have found that regeneration speed depends upon propagule availability and the intensity and duration of disturbance. However, reestablishment of species interactions is still poorly understood and this limits our understanding of the anthropogenic impacts upon ecosystem resilience. This is the first investigation that evaluates plant-herbivore interaction networks during secondary succession. In particular we investigated succession in a Mexican tropical dry forest using data of caterpillar associations with plants during 2007-2010. Plant-herbivore networks showed high resilience. We found no differences in most network descriptors between secondary and mature forest and only recently abandoned fields were found to be different. No significant nestedness or modularity network structure was found. Plant-herbivore network properties appear to quickly reestablish after perturbation, despite differences in species richness and composition. This study provides some valuable guidelines for the implement of restoration efforts that can enhance ecological processes such as the interaction between plants and their herbivores.
| S-EPMC3531414 | biostudies-literature
Project description:Background and aimsStereochemical variation is widely known to influence the bioactivity of compounds in the context of pharmacology and pesticide science, but our understanding of its importance in mediating plant-herbivore interactions is limited, particularly in field settings. Similarly, sesquiterpene lactones are a broadly distributed class of putative defensive compounds, but little is known about their activities in the field.MethodsNatural variation in sesquiterpene lactones of the common cocklebur, Xanthium strumarium (Asteraceae), was used in conjunction with a series of common garden experiments to examine relationships between stereochemical variation, herbivore damage and plant fitness.Key resultsThe stereochemistry of sesquiterpene lactone ring junctions helped to explain variation in plant herbivore resistance. Plants producing cis-fused sesquiterpene lactones experienced significantly higher damage than plants producing trans-fused sesquiterpene lactones. Experiments manipulating herbivore damage above and below ambient levels found that herbivore damage was negatively correlated with plant fitness. This pattern translated into significant fitness differences between chemotypes under ambient levels of herbivore attack, but not when attack was experimentally reduced via pesticide.ConclusionsTo our knowledge, this work represents only the second study to examine sesquiterpene lactones as defensive compounds in the field, the first to document herbivore-mediated natural selection on sesquiterpene lactone variation and the first to investigate the ecological significance of the stereochemistry of the lactone ring junction. The results indicate that subtle differences in stereochemistry may be a major determinant of the protective role of secondary metabolites and thus of plant fitness. As stereochemical variation is widespread in many groups of secondary metabolites, these findings suggest the possibility of dynamic evolutionary histories within the Asteraceae and other plant families showing extensive stereochemical variation.
| S-EPMC3936589 | biostudies-literature
Project description:Plants face attackers aboveground and belowground. Insect root herbivores can lead to severe crop losses, yet the underlying transcriptomic responses have rarely been studied. We studied the dynamics of the transcriptomic response of Brussels sprouts (Brassica oleracea var. gemmifera) primary roots to feeding damage by cabbage root fly larvae (Delia radicum), alone or in combination with aboveground herbivory by cabbage aphids (Brevicoryne brassicae) or diamondback moth caterpillars (Plutella xylostella). This was supplemented with analyses of phytohormones and the main classes of secondary metabolites; aromatic, indole and aliphatic glucosinolates. Root herbivory leads to major transcriptomic rearrangement that is modulated by aboveground feeding caterpillars, but not aphids, through priming soon after root feeding starts. The root herbivore downregulates aliphatic glucosinolates. Knocking out aliphatic glucosinolate biosynthesis with CRISPR-Cas9 results in enhanced performance of the specialist root herbivore, indicating that the herbivore downregulates an effective defence. This study advances our understanding of how plants cope with root herbivory and highlights several novel aspects of insect-plant interactions for future research. Further, our findings may help breeders develop a sustainable solution to a devastating root pest.
| S-EPMC9540780 | biostudies-literature
Project description:Herbivores must overcome a variety of plant defenses, including coping with plant secondary compounds (PSCs). To help detoxify these defensive chemicals, several insect herbivores are known to harbor gut microbiota with the metabolic capacity to degrade PSCs. Leaf-cutter ants are generalist herbivores, obtaining sustenance from specialized fungus gardens that act as external digestive systems and which degrade the diverse collection of plants foraged by the ants. There is in vitro evidence that certain PSCs harm Leucoagaricus gongylophorus, the fungal cultivar of leaf-cutter ants, suggesting a role for the Proteobacteria-dominant bacterial community present within fungus gardens. In this study, we investigated the ability of symbiotic bacteria present within fungus gardens of leaf-cutter ants to degrade PSCs. We cultured fungus garden bacteria, sequenced the genomes of 42 isolates, and identified genes involved in PSC degradation, including genes encoding cytochrome P450 enzymes and genes in geraniol, cumate, cinnamate, and α-pinene/limonene degradation pathways. Using metatranscriptomic analysis, we showed that some of these degradation genes are expressed in situ Most of the bacterial isolates grew unhindered in the presence of PSCs and, using gas chromatography-mass spectrometry (GC-MS), we determined that isolates from the genera Bacillus, Burkholderia, Enterobacter, Klebsiella, and Pseudomonas degrade α-pinene, β-caryophyllene, or linalool. Using a headspace sampler, we show that subcolonies of fungus gardens reduced α-pinene and linalool over a 36-h period, while L. gongylophorus strains alone reduced only linalool. Overall, our results reveal that the bacterial communities in fungus gardens play a pivotal role in alleviating the effect of PSCs on the leaf-cutter ant system.IMPORTANCE Leaf-cutter ants are dominant neotropical herbivores capable of deriving energy from a wide range of plant substrates. The success of leaf-cutter ants is largely due to their external gut, composed of key microbial symbionts, specifically, the fungal mutualist L. gongylophorus and a consistent bacterial community. Both symbionts are known to have critical roles in extracting energy from plant material, yet comparatively little is known about their roles in the detoxification of plant secondary compounds. In this study, we assessed if the bacterial communities associated with leaf-cutter ant fungus gardens can degrade harmful plant chemicals. We identify plant secondary compound detoxification in leaf-cutter ant gardens as a process that depends on the degradative potential of both the bacterial community and L. gongylophorus Our findings suggest that the fungus garden and its associated microbial community influence the generalist foraging abilities of the ants, underscoring the importance of microbial symbionts in plant substrate suitability for herbivores.
| S-EPMC7492740 | biostudies-literature
Project description:The effects of ambient temperature and dietary plant toxins on differential gene expression in the liver were compared in herbivorous rodents (woodrats, genus Neotoma) using microarrays custom-designed for woodrats. Expression profiles revealed a greater number of up-egulated genes at 22C comapred to a thermoneutral temperature (27C). Genes and pathways up-regulated at 22C were related to growth and biosynthesis, suggesting the liver could be in a building state at this temperature. Conversely, genes associated with gluconeogenesis, apoptosis and protein misfolding, which likely reflected a more stressed state for the liver. Taken together, these results highlighted the important role of temperature on gene expression profiles in the desert woodrat. As crucial players in many ecosystems, understanding how herbivorous mammals will respond to climate change is imperative to accurately predict repercussions and aid in conservation efforts.
2017-05-02 | GSE80595 | GEO
Project description:BACKGROUND: ICE (Inducer of CBF Expression) family genes play an important role in the regulation of cold tolerance pathways. In an earlier study, we isolated the gene CdICE1 from Chrysanthemum dichrum and demonstrated that freezing tolerance was enhanced by CdICE1 overexpression. Therefore, we sought to determine the mechanism by which ICE1 family genes participate in freezing tolerance. RESULTS: Using EMSA (Electrophoretic Mobility Shift Assay) and yeast one-hybrid assays, we confirmed that CdICE1 binds specifically to the MYC element in the CdDREBa promoter and activates transcription. In addition, overexpression of CdICE1 enhanced Arabidopsis freezing tolerance after transition from 23°C to 4°C or 16°C. We found that after acclimation to 4°C, CdICE1, like Arabidopsis AtICE1, promoted expression of CBFs (CRT/DRE Binding Factor) and their genes downstream involved in freezing tolerance, including COR15a (Cold-Regulated 15a), COR6.6, and RD29a (Responsive to Dessication 29a). Interestingly, we observed that CdICE1-overexpressing plants experienced significant reduction in miR398. In addition, its target genes CSD1 (Copper/zinc Superoxide Dismutase 1) and CSD2 showed inducible expression under acclimation at 16°C, indicating that the miR398-CSD pathway was involved in the induction of freezing tolerance. CONCLUSIONS: Our data indicate that CdICE1-mediated freezing tolerance occurs via different pathways, involving either CBF or miR398, under acclimation at two different temperatures.
| S-EPMC3895800 | biostudies-other
Project description:Material development requires in many cases information about the necessary stability of the materials against oxidation, which is encoded in the chemical activity of the constituting elements. Determination of the chemical activity is tedious, especially for metallic materials at or close to ambient temperature. To determine the chemical activity of Zn at ambient temperature, electromotive force (EMF) measurements on the intermetallic compounds ZnPd, ZnPt and Cu5 Zn8 within their respective homogeneity range were conducted. The single-phase nature of the samples was confirmed by powder X-ray diffraction, light microscopy as well as SEM/EDX analysis. To exclude oxidation, and therefore faulty determination of the electrochemical potentials, a method was developed to conduct the electrochemical measurements under non-corrosive conditions in inert atmosphere. Corrosion by the electrolyte was avoided using anhydrous dimethylformamide as aprotic solvent. From the EMF the respective intrinsic activities of zinc in the corresponding intermetallic compounds was determined. Measurements on Cu5 Zn8 and comparison to available data in literature verified the developed method allowing to retrieve thermodynamic data of ZnPd and ZnPt for the first time at ambient temperature. The herein developed and easy-to-use methodology is applicable to a wide range of metallic material by choosing appropriate compositions of the electrolyte and has the potential to boost material development.
| S-EPMC7318324 | biostudies-literature
Project description:Co-occurrence patterns in the gut microbiota of a specialist herbivore and its host plant from natural populations
| PRJEB26629 | ENA
Project description:1. Herbivores influence the structure and composition of terrestrial plant communities. However, responses of plant communities to herbivory are variable and depend on environmental conditions, herbivore identity and herbivore abundance. As anthropogenic impacts continue to drive large declines in wild herbivores, understanding the context dependence of herbivore impacts on plant communities becomes increasingly important. 2. Exclosure experiments are frequently used to assess how ecosystems reorganize in the face of large wild herbivore defaunation. Yet in many landscapes, declines in large wildlife are often accompanied by other anthropogenic activities, especially land conversion to livestock production. In such cases, exclosure experiments may not reflect typical outcomes of human-driven extirpations of wild herbivores. 3. Here, we examine how plant community responses to changes in the identity and abundance of large herbivores interact with abiotic factors (rainfall and soil properties). We also explore how effects of wild herbivores on plant communities differ between large-scale herbivore exclosures and landscape sites where anthropogenic activity has caused wildlife declines, often accompanied by livestock increases. 4. Abiotic context modulated the responses of plant communities to herbivore declines with stronger effect sizes in lower-productivity environments. Also, shifts in plant community structure, composition and species richness following wildlife declines differed considerably between exclosure experiments and landscape sites in which wild herbivores had declined and were often replaced by livestock. Plant communities in low wildlife landscape sites were distinct in both composition and physical structure from both exclosure and control sites in experiments. The power of environmental (soil and rainfall) gradients in influencing plant response to herbivores was also greatly dampened or absent in the landscape sites. One likely explanation for these observed differences is the compensatory effect of livestock associated with the depression or extirpation of wildlife. 5.Synthesis. Our results emphasize the importance of abiotic environmental heterogeneity in modulating the effects of mammalian herbivory on plant communities and the importance of such covariation in understanding effects of wild herbivore declines. They also suggest caution when extrapolating results from exclosure experiments to predict the consequences of defaunation as it proceeds in the Anthropocene.
| S-EPMC3758959 | biostudies-literature