The Myriad Plant Responses to Herbivores.
TL;DR: Differential expression of plant genes in response to closely related insect species suggest that some elicitors generated by phloem-feeding insects are species-specific and are dependent on the herbivore's developmental stage.
Abstract: Plant responses to herbivores are complex. Genes activated on herbivore attack are strongly correlated with the mode of herbivore feeding and the degree of tissue damage at the feeding site. Phloem-feeding whiteflies and aphids that produce little injury to plant foliage are perceived as pathogens and activate the salicylic acid (SA)-dependent and jasmonic acid (JA)/ethylene-dependent signaling pathways. Differential expression of plant genes in response to closely related insect species suggest that some elicitors generated by phloem-feeding insects are species-specific and are dependent on the herbivore's developmental stage. Other elicitors for defense-gene activation are likely to be more ubiquitous. Analogies to the pathogen-incompatible reactions are found. Chewing insects such as caterpillars and beetles and cell-content feeders such as mites and thrips cause more extensive tissue damage and activate wound-signaling pathways. Herbivore feeding is not equivalent to mechanical wounding. Wound responses are a part of the induced responses that accompany herbivore feeding. Herbivores induce direct defenses that interfere with herbivore feeding, growth and development, fecundity, and fertility. In addition, herbivores induce an array of volatiles that creates an indirect mechanism of defense. Volatile blends provide specific cues to attract herbivore parasites and predators to infested plants. The nature of the elicitors for volatile production is discussed.
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TL;DR: This review summarizes biosynthesis and signal transduction of jasmonates with emphasis on new findings in relation to enzymes, their crystal structure, new compounds detected in the oxylipin andJasmonate families, and newly found functions.
1,687 citations
Book•
01 Jan 2005
TL;DR: An excellent introduction and overview of this field, written by Volker Grimm and Steven F. Railsback, should be read by everyone interested in individual-based modeling and especially by anyone contemplating developing, or being involved with a group developing, an individualbased model.
Abstract: Individual-based modeling is a new, exciting discipline that allows ecologists to explore, using computer simulations, how properties of populations and ecosystems might evolve from the characteristics and behaviors of individual organisms. Individual-based Modeling and Ecology, written by Volker Grimm and Steven F. Railsback, gives an excellent introduction and overview of this field. It should be read by everyone interested in individual-based modeling, and especially by anyone contemplating developing, or being involved with a group developing, an individualbased model.
1,495 citations
Cites background from "The Myriad Plant Responses to Herbi..."
...For example, plants can respond to insect herbivores by releasing chemicals that attack the insects directly by interfering with feeding, growth, and ability to reproduce; and indirectly by attracting the insects’ predators and parasites (Walling 2000)....
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TL;DR: Large-scale transcriptional changes accompany insect-induced resistance, which is organized into specific temporal and spatial patterns and points to the existence of herbivore-specific trans-activating elements orchestrating the responses.
Abstract: ▪ Abstract Plants respond to herbivore attack with a bewildering array of responses, broadly categorized as direct and indirect defenses, and tolerance. Plant-herbivore interactions are played out on spatial scales that include the cellular responses, well-studied in plant-pathogen interactions, as well as responses that function at whole-plant and community levels. The plant's wound response plays a central role but is frequently altered by insect-specific elicitors, giving plants the potential to optimize their defenses. In this review, we emphasize studies that advance the molecular understanding of elicited direct and indirect defenses and include verifications with insect bioassays. Large-scale transcriptional changes accompany insect-induced resistance, which is organized into specific temporal and spatial patterns and points to the existence of herbivore-specific trans-activating elements orchestrating the responses. Such organizational elements could help elucidate the molecular control over the d...
1,423 citations
TL;DR: Activation of this pathway as an initial step in the interaction of plants with pathogens, insects, or abiotic stress and at distinct stages of development are reviewed.
Abstract: Lipid peroxidation is common to all biological systems, both appearing in developmentally and environmentally regulated processes of plants. The hydroperoxy polyunsaturated fatty acids, synthesized by the action of various highly specialized forms of lipoxygenases, are substrates of at least seven different enzyme families. Signaling compounds such as jasmonates, antimicrobial and antifungal compounds such as leaf aldehydes or divinyl ethers, and a plant-specific blend of volatiles including leaf alcohols are among the numerous products. Cloning of many lipoxygenases and other key enzymes within the lipoxygenase pathway, as well as analyses by reverse genetic and metabolic profiling, revealed new reactions and the first hints of enzyme mechanisms, multiple functions, and regulation. These aspects are reviewed with respect to activation of this pathway as an initial step in the interaction of plants with pathogens, insects, or abiotic stress and at distinct stages of development.
1,340 citations
TL;DR: By understanding the mechanisms of induced resistance, this work can predict the herbivores that are likely to be affected by induced responses and could be exploited as an important tool for the pest management to minimize the amounts of insecticides used for pest control.
Abstract: Plants respond to herbivory through various morphological, biochemicals, and molecular mechanisms to counter/offset the effects of herbivore attack. The biochemical mechanisms of defense against the herbivores are wide-ranging, highly dynamic, and are mediated both by direct and indirect defenses. The defensive compounds are either produced constitutively or in response to plant damage, and affect feeding, growth, and survival of herbivores. In addition, plants also release volatile organic compounds that attract the natural enemies of the herbivores. These strategies either act independently or in conjunction with each other. However, our understanding of these defensive mechanisms is still limited. Induced resistance could be exploited as an important tool for the pest management to minimize the amounts of insecticides used for pest control. Host plant resistance to insects, particularly, induced resistance, can also be manipulated with the use of chemical elicitors of secondary metabolites, which confer resistance to insects. By understanding the mechanisms of induced resistance, we can predict the herbivores that are likely to be affected by induced responses. The elicitors of induced responses can be sprayed on crop plants to build up the natural defense system against damage caused by herbivores. The induced responses can also be engineered genetically, so that the defensive compounds are constitutively produced in plants against are challenged by the herbivory. Induced resistance can be exploited for developing crop cultivars, which readily produce the inducible response upon mild infestation, and can act as one of components of integrated pest management for sustainable crop production.
1,296 citations
Cites background from "The Myriad Plant Responses to Herbi..."
..., that influence the performance and survival of the herbivores.(29) The secondary metabolites not only defend the plants from different stresses, but also increase the fitness of the plants....
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...Depending upon the modes of feeding of insect pests, different defense signaling pathways are activated, which induce the production of specific volatile compounds.(29) The HIPVs include terpenes, green leafy volatiles (GLVs), ethylene, methyl salicylate and other VOCs....
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References
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01 Jun 1997
TL;DR: Emerging data indicate that the oxidative burst reflects activation of a membrane-bound NADPH oxidase closely resembling that operating in activated neutrophils, which underlies the expression of disease-resistance mechanisms.
Abstract: Rapid generation of superoxide and accumulation of H2O2 is a characteristic early feature of the hypersensitive response following perception of pathogen avirulence signals. Emerging data indicate that the oxidative burst reflects activation of a membrane-bound NADPH oxidase closely resembling that operating in activated neutrophils. The oxidants are not only direct protective agents, but H2O2 also functions as a substrate for oxidative cross-linking in the cell wall, as a threshold trigger for hypersensitive cell death, and as a diffusible signal for induction of cellular protectant genes in surrounding cells. Activation of the oxidative burst is a central component of a highly amplified and integrated signal system, also involving salicylic acid and perturbations of cytosolic Ca2+, which underlies the expression of disease-resistance mechanisms.
3,203 citations
Book•
01 Jan 1997TL;DR: This comprehensive evaluation and synthesis of a rapidly-developing field provides state-of-the-discipline reviews, and highlights areas of research which might be productive, should appeal to a wide variety of theoretical and applied researchers.
Abstract: Plants face a daunting array of creatures which eat them, bore into them and use virtually every plant part for food or shelter. However, plants are far from defenceless under attack. Although they cannot flee their attackers, they can produce defences, such as thorns, and can actively alter their chemistry and physiology in response to damage. For instance, young potato leaves being eaten by potato beetles respond by producing chemicals which inhibit beetle digestive enzymes. Research on these induced responses to herbivory has proceeded since the 1980s, and this comprehensive evaluation and synthesis of a rapidly-developing field provides state-of-the-discipline reviews, and highlights areas of research which might be productive. This overview should appeal to a wide variety of theoretical and applied researchers in ecology, evolutionary biology, plant biology, entomology and agriculture.
2,385 citations
TL;DR: Data point to the existence of at least two separate hormone-dependent defense pathways in Arabidopsis that contribute to resistance against distinct microbial pathogens.
Abstract: The endogenous plant hormones salicylic acid (SA) and jasmonic acid (JA), whose levels increase on pathogen infection, activate separate sets of genes encoding antimicrobial proteins in Arabidopsis thaliana. The pathogen-inducible genes PR-1, PR-2, and PR-5 require SA signaling for activation, whereas the plant defensin gene PDF1.2, along with a PR-3 and PR-4 gene, are induced by pathogens via an SA-independent and JA-dependent pathway. An Arabidopsis mutant, coi1, that is affected in the JA-response pathway shows enhanced susceptibility to infection by the fungal pathogens Alternaria brassicicola and Botrytis cinerea but not to Peronospora parasitica, and vice versa for two Arabidopsis genotypes (npr1 and NahG) with a defect in their SA response. Resistance to P. parasitica was boosted by external application of the SA-mimicking compound 2,6-dichloroisonicotinic acid [Delaney, T., et al. (1994) Science 266, 1247–1250] but not by methyl jasmonate (MeJA), whereas treatment with MeJA but not 2,6-dichloroisonicotinic acid elevated resistance to Alternaria brassicicola. The protective effect of MeJA against A. brassicicola was the result of an endogenous defense response activated in planta and not a direct effect of MeJA on the pathogen, as no protection to A. brassicicola was observed in the coi1 mutant treated with MeJA. These data point to the existence of at least two separate hormone-dependent defense pathways in Arabidopsis that contribute to resistance against distinct microbial pathogens.
1,468 citations
TL;DR: The production by phylogenetically diverse plant species and the exploitation by parasitoids of highly specific chemical signals, keyed to individual herbivore species, indicates that the interaction between plants and the natural enemies of the herbivores that attack them is more sophisticated than previously realized.
Abstract: 1-3 . Here we use chemical and behavioural assays to show that these plant emissions can transmit herbivore-specific infor- mation that is detectable by parasitic wasps (parasitoids). Tobacco, cotton and maize plants each produce distinct volatile blends in response to damage by two closely related herbivore species, Heliothis virescens and Helicoverpa zea. The specialist parasitic wasp Cardiochiles nigriceps exploits these differences to distinguish infestation by its host, H. virescens, from that by H. zea. The production by phylogenetically diverse plant species and the exploitation by parasitoids of highly specific chemical signals, keyed to individual herbivore species, indicates that the interaction between plants and the natural enemies of the herbi- vores that attack them is more sophisticated than previously realized. Herbivore-induced plant signals are important for the foraging success of parasitoids and for the plants' defence 3-8 . The production and release of volatiles is triggered at least in part by substance(s) in the oral secretion of herbivores 2,9 ; in cotton, this is known to be an active process in which several terpenoids are synthesized de novo in response to insect feeding 10 . The chemical composition of released volatiles varies among plant tissues (cotton leaves, flowers and bolls, for example) 11 , varieties 12 and cultivars 13 . Although volatile emis-
1,237 citations