Insect herbivores should follow plants escaping their relatives.
Ontology highlight
ABSTRACT:
SUBMITTER: Yguel B
PROVIDER: S-EPMC4161943 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Arabidopsis thaliana plants were infested i) with sucking insect herbivores (the generalist aphid Myzus persicae and the specialist aphid Brevicoryne brassicae), ii) with chewing insect herbivores (generalist caterpillars of Spodoptera exigua and specialist caterpillars of Pieris rapae) or iii) were treated by wounding. For each treatment, rosette leaves were harvested at two time points (6h and 24h) after removal of insects. For chewing herbivores and wounding both local, i.e. immediately damaged leaves, and systemic, i.e. undamaged leaves from the same plant, were collected. Control plants were uninfested, but otherwise equally treated and harvested in parallel. We tested the hypothesis that Arabidopsis can recognize and respond differentially to insect species at the transcriptional level using a genome wide microarray. Transcriptional reprogramming was characterized using co-expression analysis in damaged and undamaged leaves at two times in response to mechanical wounding and four insect species. In all, 2778 (10.6%) of annotated genes on the array were differentially expressed in at least one treatment. Responses differed mainly between aphid and caterpillar and sampling times. Responses to aphids and caterpillars shared only 10% of up-regulated and 8% of down-regulated genes. Responses to two caterpillars shared 21% and 12% of up- and down-regulated genes, whereas responses to the two aphids shared only 7% and 4% of up-regulated and down-regulated genes. Overlap in genes expressed between 6h and 24h was 3-15%, and depended on the insect species. Responses in attacked and unattacked leaves differed at 6h but converged by 24h. Genes responding to the insects are also responsive to many stressors and included primary metabolism. Aphids down-regulated amino acid catabolism; caterpillars stimulated production of amino acids involved in glucosinolate synthesis. Co-expression analysis revealed 17 response networks. Transcription factors were a major portion of differentially expressed genes throughout and responsive genes shared most of the known or postulated binding sites.
2015-10-05 | GSE62287 | GEO
Project description:A parasite-infected host may promote performance of associated insect vectors; but possible parasite effects on nonvector insects have been largely unexplored. Here, we show that Begomovirus, the largest genus of plant viruses and transmitted exclusively by whitefly, reprogram plant immunity to promote the fitness of the vector and suppress performance of nonvector insects (i.e., cotton bollworm and aphid). Infected plants accumulated begomoviral βC1 proteins in the phloem where they were bound to the plant transcription factor WRKY20. This viral hijacking of WRKY20 spatiotemporally redeployed plant chemical immunity within the leaf and had the asymmetrical benefiting effects on the begomoviruses and its whitefly vectors while negatively affecting two nonvector competitors. This type of interaction between a parasite and two types of herbivores, i.e., vectors and nonvectors, occurs widely in various natural and agricultural ecosystems; thus, our results have broad implications for the ecological significance of parasite-vector-host tripartite interactions.
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Project description:Understanding variation in resource specialization is important for progress on issues that include coevolution, community assembly, ecosystem processes, and the latitudinal gradient of species richness. Herbivorous insects are useful models for studying resource specialization, and the interaction between plants and herbivorous insects is one of the most common and consequential ecological associations on the planet. However, uncertainty persists regarding fundamental features of herbivore diet breadth, including its relationship to latitude and plant species richness. Here, we use a global dataset to investigate host range for over 7,500 insect herbivore species covering a wide taxonomic breadth and interacting with more than 2,000 species of plants in 165 families. We ask whether relatively specialized and generalized herbivores represent a dichotomy rather than a continuum from few to many host families and species attacked and whether diet breadth changes with increasing plant species richness toward the tropics. Across geographic regions and taxonomic subsets of the data, we find that the distribution of diet breadth is fit well by a discrete, truncated Pareto power law characterized by the predominance of specialized herbivores and a long, thin tail of more generalized species. Both the taxonomic and phylogenetic distributions of diet breadth shift globally with latitude, consistent with a higher frequency of specialized insects in tropical regions. We also find that more diverse lineages of plants support assemblages of relatively more specialized herbivores and that the global distribution of plant diversity contributes to but does not fully explain the latitudinal gradient in insect herbivore specialization.
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Project description:Ecological immunology examines the adaptive responses of animals to pathogens in relation to other environmental factors and explores the consequences of trade-offs between investment in immune function and other life-history traits. Among species of herbivorous insects, diet breadth may vary greatly, with generalists consuming a wide variety of plant families and specialists restricted to a few species. Generalists may thus be exposed to a wider range of pathogens exerting stronger selection on the innate immune system. To examine whether this produces an increase in the robustness of the immune response, we compared larvae of the generalist herbivore Heliothis virescens and the specialist Heliothis subflexa challenged by entomopathogenic and non-pathogenic bacteria. Heliothis virescens larvae showed lower mortality, a lower number of recoverable bacteria, lower proliferation of haemocytes and higher phagocytic activity. These results indicate a higher tolerance to entomopathogenic bacteria by the generalist, which is associated with a more efficient cell-mediated immune response by mechanisms that differ between these closely related species. Our findings provide novel insights into the consequences of diet breadth and related environmental factors, which may be significant in further studies to understand the ecological forces and investment trade-offs that shape the evolution of innate immunity.
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Project description:Insect herbivore damage and abundance are often reduced in diverse plant stands. However, few studies have explored whether this phenomenon is a result of plant diversity effects on host plant traits. We explored indirect effects of tree species diversity on herbivory via changes in leaf traits in a long-term forest diversity experiment in Finland. We measured 16 leaf traits and leaf damage by four insect guilds (chewers, gall formers, leaf miners and rollers) on silver birch (Betula pendula) trees growing in one-, two-, three- and five-species mixtures. A decline in the frequency of birch in mixed stands resulted in reduced leaf area. This, in turn, mediated the reduction in chewing damage in mixed stands. In contrast, associational resistance of birch to leaf miners was not trait-mediated but driven directly by concurrent declines in birch frequency as tree species richness increased. Our results show that leaf trait variation across the diversity gradient might promote associational resistance, but these patterns are driven by an increase in the relative abundance of heterospecifics rather than by tree species richness per se. Therefore, accounting for concurrent changes in stand structure and key foliar traits is important for the interpretation of plant diversity effects and predictions of associational patterns.
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Project description:Insect herbivores exploit plant cues to discern host and non-host plants. Studies of visual plant cues have focused on colour despite the inherent polarization sensitivity of insect photoreceptors and the information carried by polarization of foliar reflectance, most notably the degree of linear polarization (DoLP; 0-100%). The DoLP of foliar reflection was hypothesized to be a host plant cue for insects but was never experimentally tested. Here, we show that cabbage white butterflies, Pieris rapae (Pieridae), exploit the DoLP of foliar reflections to discriminate among plants. In experiments with paired digital plant images, P. rapae females preferred images of the host plant cabbage with a low DoLP (31%) characteristic of cabbage foliage over images of a non-host potato plant with a higher DoLP (50%). By reversing the DoLP of these images, we were able to shift the butterflies' preference for the cabbage host plant image to the potato non-host plant image, indicating that the DoLP had a greater effect on foraging decisions than the differential colour, intensity, or shape of the two plant images. Although previously not recognized, the DoLP of foliar reflection is an essential plant cue that may commonly be exploited by foraging insect herbivores.
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Project description:Gene duplication is a major source of plant chemical diversity that mediates plant-herbivore interactions. There is little direct evidence, however, that novel chemical traits arising from gene duplication reduce herbivory. Higher plants use threonine deaminase (TD) to catalyze the dehydration of threonine (Thr) to ?-ketobutyrate and ammonia as the committed step in the biosynthesis of isoleucine (Ile). Cultivated tomato and related Solanum species contain a duplicated TD paralog (TD2) that is coexpressed with a suite of genes involved in herbivore resistance. Analysis of TD2-deficient tomato lines showed that TD2 has a defensive function related to Thr catabolism in the gut of lepidopteran herbivores. During herbivory, the regulatory domain of TD2 is removed by proteolysis to generate a truncated protein (pTD2) that efficiently degrades Thr without being inhibited by Ile. We show that this proteolytic activation step occurs in the gut of lepidopteran but not coleopteran herbivores, and is catalyzed by a chymotrypsin-like protease of insect origin. Analysis of purified recombinant enzymes showed that TD2 is remarkably more resistant to proteolysis and high temperature than the ancestral TD1 isoform. The crystal structure of pTD2 provided evidence that electrostatic interactions constitute a stabilizing feature associated with adaptation of TD2 to the extreme environment of the lepidopteran gut. These findings demonstrate a role for gene duplication in the evolution of a plant defense that targets and co-opts herbivore digestive physiology.
| S-EPMC3078374 | biostudies-literature
Project description:We tested the hypothesis that Arabidopsis can recognize and respond differentially to insect species at the transcriptional level using a genome wide microarray. Transcriptional reprogramming was characterized using co-expression analysis in damaged and undamaged leaves at two times in response to mechanical wounding and four insect species. In all, 2778 (10.6%) of annotated genes on the array were differentially expressed in at least one treatment. Responses differed mainly between aphid and caterpillar and sampling times. Responses to aphids and caterpillars shared only 10% of up-regulated and 8% of down-regulated genes. Responses to two caterpillars shared 21 and 12% of up- and down-regulated genes, whereas responses to the two aphids shared only 7 and 4% of up-regulated and down-regulated genes. Overlap in genes expressed between 6 and 24 h was 3-15%, and depended on the insect species. Responses in attacked and unattacked leaves differed at 6 h but converged by 24 h. Genes responding to the insects are also responsive to many stressors and included primary metabolism. Aphids down-regulated amino acid catabolism; caterpillars stimulated production of amino acids involved in glucosinolate synthesis. Co-expression analysis revealed 17 response networks. Transcription factors were a major portion of differentially expressed genes throughout and responsive genes shared most of the known or postulated binding sites. However, cis-element composition of genes down regulated by the aphid M. persicae was unique, as were those of genes down-regulated by caterpillars. As many as 20 cis-elements were over-represented in one or more treatments, including some from well-characterized classes and others as yet uncharacterized. We suggest that transcriptional changes elicited by wounding and insects are heavily influenced by transcription factors and involve both enrichment of a common set of cis-elements and a unique enrichment of a few cis-elements in responding genes.
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Project description:The degradation of chlorophyll, the omnipresent green pigment, has been investigated intensively over the last 30 years resulting in many elucidated tetrapyrrolic degradation products. With a comparison to the degradation of the structurally similar heme, we hereby propose a novel additional chlorophyll degradation mechanism to mono- and dipyrrolic products. This is the first proof of the occurrence of a family of mono- and dipyrrols in leaves that are previously only known as heme degradation products. This product family is also found in spit and feces of herbivores with specific metabolomic patterns reflecting the origin of the samples. Based on chromatographic and mass spectrometric evidence as well as on mechanistic considerations we also suggest several tentative new degradation products. One of them, dihydro BOX A, was fully confirmed as a novel natural product by synthesis and comparison of its spectroscopic data.
| S-EPMC7318184 | biostudies-literature
Project description:Plants and herbivores have been engaged in a co-evolutionary arms race for millions of years, during which plants evolved various defenses and other traits to cope with herbivores, whereas herbivores evolved traits to overcome the plants' resistance strategies. Herbivores may also avoid certain plants merely because these lack suitable nutrients for their development. Interestingly, the number of herbivores that attack individual early land plants like mosses and ferns is quite low. Among others, poor nutrient quality has been hypothesized to explain the apparent low herbivory pressure on such plants but still waits for scientific evidences. Here, the nutritive suitability of representative mosses and liverworts (bryophytes) and ferns (pteridophytes) for herbivores was investigated using feeding assays combined with quantifications of nutrients (proteins, amino acids, and sugars). Growth and survival of two polyphagous herbivores, a caterpillar and a snail, were monitored when fed on 15 species of bryophytes and pteridophytes, as well as on maize (Zea mays, angiosperm) used as an external indicative nutritional resource. Overall, our results show that the poor performance of the herbivores on the studied early land plants is not correlated with nutritional quality. The growth and performance of snails and caterpillars fed with these plants were highly variable and independent of nutrient content. These findings arguably dismiss the poor nutrient quality hypothesis as the cause of herbivory deficit in bryophytes and pteridophytes. They suggest the possible presence of early resistance traits that have persisted all through the long evolutionary history of plant-herbivore interactions.
| S-EPMC9745390 | biostudies-literature