The Effect of Plant Defense Phytohormones on Caterpillar Herbivores PDF Download
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Author: Hongliang Su
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"Plants protect themselves against caterpillar herbivory by activating the jasmonate (JA) biosynthetic pathway that produces the bioactive form of the plant defense hormone, 7-jasmonoyl-L-isoleucine. The JA signaling pathway leads to the production of many defensive compounds. Most research has focused on the effects of these JA-dependent plant defensive compounds on the caterpillar herbivore. In comparison, relatively little is known about the direct effects of the defensive phytohormone JA and intermediates in its biosynthetic pathway on the caterpillar herbivore.This research focuses on determining the effects of defense phytohormones in the jasmonate pathway, such as 12-oxo-phytodienoic acid (OPDA) and JA, and their precursor, linolenic acid, on caterpillar development, mortality and pupal weight. The effects on two caterpillar species were compared. The cabbage looper, Trichoplusia ni (Hübner), is a facultative specialist on plants in the Brassicaceae family. In contrast, caterpillars of the beet armyworm, Spodoptera exigua (Hübner) are generalists, which means that they can feed on a diverse range of plant species.This study shows that jasmonic acid and OPDA affect S. exigua and T. ni development, pupal weight and mortality. Caterpillars fed an artificial diet containing either OPDA or JA were developmentally delayed compared to caterpillars fed the control diet (artificial diet without phytohormone). This delay was temporary and by day 12, all caterpillars reached the pupal stage. T. ni males were smaller than females when fed an artificial diet containing OPDA (4 μg/g) or JA (0.15 μg/g or 6 μg/g). T. ni males were smaller when fed an artificial diet containing OPDA (1.5 μg/g or 4 μg/g) or JA (0.15 μg/g or 6 μg/g) compared to caterpillars fed the control diet (artificial diet without phytohormone). S. exigua males were larger when fed an artificial diet containing OPDA (4 μg/g) or JA (0.15 μg/g or 6 μg/g) compared to caterpillars fed the control diet (artificial diet without phytohormone). S. exigua females fed an artificial diet containing JA (0.15 μg/g or 6 μg/g) were smaller than other female caterpillars fed the control diet (artificial diet without phytohormone). JA was moderately toxic to both caterpillar species but the other compounds tested were not. The LD50 for jasmonic acid for the two caterpillar species was determined by conducting mortality curves using 4th instar larvae of each species. The JA LD50 in T. ni and S. exigua caterpillars is 3.8 ± 0.7 μg and 5.8 ± 0.3 μg, respectively. Therefore, S. exigua caterpillars are better able to cope with JA than T. ni caterpillars. It is possible that the generalist species have enhanced mechanisms to detoxify these phytohormones.Glutathione S-transferase (GST) is an enzyme that is important for the detoxification of plant defensive compounds. GST enzyme activity was compared between T. ni and S. exigua caterpillars. S. exigua caterpillar GST activity was high (U/mg soluble protein at alkaline pH) when caterpillars were fed an artificial diet containing JA. T. ni caterpillar GST activity (U/mg soluble protein at alkaline pH) was high when caterpillars were fed an artificial diet containing OPDA or JA. The optimal pH for GST activity was at alkaline pH. This research furthers our understanding of caterpillar herbivores strategies to overcome plant resistance mechanisms"--
Author: Hongliang Su
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"Plants protect themselves against caterpillar herbivory by activating the jasmonate (JA) biosynthetic pathway that produces the bioactive form of the plant defense hormone, 7-jasmonoyl-L-isoleucine. The JA signaling pathway leads to the production of many defensive compounds. Most research has focused on the effects of these JA-dependent plant defensive compounds on the caterpillar herbivore. In comparison, relatively little is known about the direct effects of the defensive phytohormone JA and intermediates in its biosynthetic pathway on the caterpillar herbivore.This research focuses on determining the effects of defense phytohormones in the jasmonate pathway, such as 12-oxo-phytodienoic acid (OPDA) and JA, and their precursor, linolenic acid, on caterpillar development, mortality and pupal weight. The effects on two caterpillar species were compared. The cabbage looper, Trichoplusia ni (Hübner), is a facultative specialist on plants in the Brassicaceae family. In contrast, caterpillars of the beet armyworm, Spodoptera exigua (Hübner) are generalists, which means that they can feed on a diverse range of plant species.This study shows that jasmonic acid and OPDA affect S. exigua and T. ni development, pupal weight and mortality. Caterpillars fed an artificial diet containing either OPDA or JA were developmentally delayed compared to caterpillars fed the control diet (artificial diet without phytohormone). This delay was temporary and by day 12, all caterpillars reached the pupal stage. T. ni males were smaller than females when fed an artificial diet containing OPDA (4 μg/g) or JA (0.15 μg/g or 6 μg/g). T. ni males were smaller when fed an artificial diet containing OPDA (1.5 μg/g or 4 μg/g) or JA (0.15 μg/g or 6 μg/g) compared to caterpillars fed the control diet (artificial diet without phytohormone). S. exigua males were larger when fed an artificial diet containing OPDA (4 μg/g) or JA (0.15 μg/g or 6 μg/g) compared to caterpillars fed the control diet (artificial diet without phytohormone). S. exigua females fed an artificial diet containing JA (0.15 μg/g or 6 μg/g) were smaller than other female caterpillars fed the control diet (artificial diet without phytohormone). JA was moderately toxic to both caterpillar species but the other compounds tested were not. The LD50 for jasmonic acid for the two caterpillar species was determined by conducting mortality curves using 4th instar larvae of each species. The JA LD50 in T. ni and S. exigua caterpillars is 3.8 ± 0.7 μg and 5.8 ± 0.3 μg, respectively. Therefore, S. exigua caterpillars are better able to cope with JA than T. ni caterpillars. It is possible that the generalist species have enhanced mechanisms to detoxify these phytohormones.Glutathione S-transferase (GST) is an enzyme that is important for the detoxification of plant defensive compounds. GST enzyme activity was compared between T. ni and S. exigua caterpillars. S. exigua caterpillar GST activity was high (U/mg soluble protein at alkaline pH) when caterpillars were fed an artificial diet containing JA. T. ni caterpillar GST activity (U/mg soluble protein at alkaline pH) was high when caterpillars were fed an artificial diet containing OPDA or JA. The optimal pH for GST activity was at alkaline pH. This research furthers our understanding of caterpillar herbivores strategies to overcome plant resistance mechanisms"--
Author: Ching Wen Tan
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Almost all plant species are attacked by multiple herbivore species and have evolved various strategies to defend themselves. These plant defense strategies include inducible physical and chemical traits; for example, induced defensive proteins and secondary metabolites can impair herbivore growth and survival. These induced defenses rely on the recognition of herbivore presence. The oral secretions (regurgitant and saliva) of insect herbivores play a crucial role in providing cues that are recognized by plants, which then trigger plant defense responses. However, the interactions between plants and insects are considerably more complex in nature where other trophic levels are involved and can influence these interactions. Microorganisms are abundant in the environment and can impact interactions in many ways including altering the perception of herbivores by plants. Braconid parasitoids are small wasps which lay their eggs inside host caterpillars. These parasitoids possess obligate mutualistic viruses called polydnaviruses (PDVs). PDVs are injected by parasitoids with their eggs into host caterpillars. PDVs suppress caterpillar immune responses and metabolism, thus allowing parasitoid eggs to hatch and develop. In nature, 35-80% of caterpillars are parasitized, depending on locations and host plant species. However, it is not clear how parasitoid/PDVs influence plant and herbivore interactions. The main objective of this study were to: 1. Reveal the mechanism and impacts of the parasitoid and its PDV (Microplitis croceipes) on tomato plant defenses through its host caterpillar (Helicoverpa zea); 2. Evaluate the consequences of parasitoid suppression of induced plant defenses on plant fitness; and 3. Determine if the parasitoid effect on plant defenses are commonly present in other plant and insect systems. These objectives were approached by a series of biochemical, physiological and molecular experiments and results provide solid evidence to support the hypothesis that plants can distinguish between feeding by parasitized and non-parasitized caterpillars, thus altering their defense responses accordingly. Microplitis croceipes parasitized Helicoverpa zea larvae produced lower elicitor activity in their saliva (i.e., glucose oxidase) compared with non-parasitized caterpillars, and significantly downregulated tomato defense-related gene expression and defense protein activities during feeding. The ultimate cause of downregulation of plant defense responses was due to the obligate mutualist PDVs of the parasitoid. PDVs suppressed GOX gene expression and activity in parasitized caterpillar salivary glands thereby downregulating plant defense responses. The lower induced plant defenses benefit the parasitoid by promoting parasitized caterpillar growth performance, producing heavier cocoon mass and overall higher parasitoid survival rate. Besides, tomato plants treated by parasitized caterpillar saliva had significantly higher fitness (increased flower number and fruit weight) compared to those treated by non-parasitized caterpillars. These results support the hypothesis that plants benefit from parasitoids indirectly. This is a previously unidentified benefit of parasitoids on plant productivity/fitness. Two other plant and insect systems were also tested and confirmed that parasitoids can indirectly influence plants perception of insect herbivores. These findings have revealed a novel aspect of microbe-mediated interactions between plants and insects. The symbiotic PDV virus not only alters the phenotype of its primary host (i.e., parasitoid) and secondary host (i.e., caterpillar), but also the host plant of the caterpillar. This is the most extreme example of the extended phenotype known: a virus phenotype that extends across three trophic levels. This work has important implications for the evolutionary ecology of plant-herbivore-parasitoid interactions and points out a new perspective of mutualism between plants and parasitoids.
Author:
Publisher: Academic Press
ISBN: 0080925456
Category : Technology & Engineering
Languages : zh-CN
Pages : 506
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Book Description
This volume presents the latest research on herbivores, aquatic and terrestrial mammals and insects. The Second Edition, written almost entirely by new authors, effectively complements the initial work. It includes advances in molecular biology and microbiology, ecology, and evolutionary theory that have been achieved since the first edition was published in 1979. The book also incorporates relatively new methodologies in the area of molecular biology, like protein purification and gene cloning. Volume II, Ecological and Evolutionary Processes, also opens up entirely new subjects: The discussions of interactions have expanded to include phenomena at higher trophic levels, such as predation and microbial processing and other environmental influences. Both this and Volume I, The Chemical Participants, will be of interest to chemists, biochemists, plant and insect ecologists, evolutionary biologists, physiologists, entomologists, and agroecologists interested in both crop and animal science. Presents coevolution of herbivores and host plants Examines resource availability and its effects on secondary metabolism and herbivores Studies physiology and biochemistry of adaptation to hosts Includes tri-trophic interactions involving predators and microbes
Author: Girdhar K. Pandey
Publisher: John Wiley & Sons
ISBN: 1118888928
Category : Science
Languages : de
Pages : 1114
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Book Description
Plant hormone signaling plays an important role in many physiological and developmental processes including stress response. With the advent of new post-genomic molecular techniques, the potential for increasing our understanding of the impact of hormone signaling on gene expression and adaptive processes has never been higher. Unlocking the molecular underpinnings of these processes shows great promise for the development of new plant biotechnologies and improved crop varieties. The topics included in this book emphasize on genomics and functional genomics aspects, to understand the global and whole genome level changes upon particular stress conditions. With the functional genomics tools, the mechanism of phytohormone signaling and their target genes can be defined in a more systematic manner. The integrated analysis of phytohormone signaling under single or multiple stress conditions may prove exceptional to design stress tolerant crop plants in the field conditions. Bringing together the latest advances, as well as the work being done to apply these findings to plant and crop science, Mechanism of Plant Hormone Signaling Under Stress will prove extremely useful to plant and stress biologists, plant biotechnology researchers, as well as students and teachers.
Author: Reginald B. Cocroft
Publisher: Springer
ISBN: 3662436078
Category : Science
Languages : en
Pages : 458
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Book Description
This volume explains the key ideas, questions and methods involved in studying the hidden world of vibrational communication in animals. The authors dispel the notion that this form of communication is difficult to study and show how vibrational signaling is a key to social interactions in species that live in contact with a substrate, whether it be a grassy lawn, a rippling stream or a tropical forest canopy. This ancient and widespread form of social exchange is also remarkably understudied. A frontier in animal behavior, it offers unparalleled opportunities for discovery and for addressing general questions in communication and social evolution. In addition to reviews of advances made in the study of several animal taxa, this volume also explores topics such as vibrational communication networks, the interaction of acoustic and vibrational communication, the history of the field, the evolution of signal production and reception and establishing a common vocabulary.
Author: James D. Blande
Publisher: Springer
ISBN: 3319334980
Category : Science
Languages : en
Pages : 325
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Book Description
This book provides an overview of the intricacies of plant communication via volatile chemicals. Plants produce an extraordinarily vast array of chemicals, which provide community members with detailed information about the producer’s identity, physiology and phenology. Volatile organic chemicals, either as individual compounds or complex chemical blends, are a communication medium operating between plants and any organism able to detect the compounds and respond. The ecological and evolutionary origins of particular interactions between plants and the greater community have been, and will continue to be, strenuously debated. However, it is clear that chemicals, and particularly volatile chemicals, constitute a medium akin to a linguistic tool. As well as possessing a rich chemical vocabulary, plants are known to detect and respond to chemical cues. These cues can originate from neighbouring plants, or other associated community members. This book begins with chapters on the complexity of chemical messages, provides a broad perspective on a range of ecological interactions mediated by volatile chemicals, and extends to cutting edge developments on the detection of chemicals by plants.
Author: Andreas Schaller
Publisher: Springer Science & Business Media
ISBN: 1402081820
Category : Science
Languages : en
Pages : 450
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Book Description
This timely book provides an overview of the anatomical, chemical, and developmental features contributing to plant defense, with an emphasis on plant responses that are induced by wounding or herbivore attack. The book first introduces general concepts of direct and indirect defenses, followed by a focused review of the different resistance traits. Finally, signal perception and transduction mechanism for the activation of plant defense responses are discussed.
Author: Flor Acevedo
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Feeding by insect herbivores induces defense responses in plants. Numerous studies have shown that plants recognize the mechanical damage as well as a variety of herbivore-derived cues present in insect oral secretions, saliva and frass to activate the production of specific defenses responses. Plant defenses negatively affect herbivore fitness; therefore to be able to feed on plants, insects need to develop specific adaptations to overcome defenses of their hosts. This can be challenging for herbivores that feed on a wide range of plants with diverse structural and biochemical defenses. In this dissertation, I studied defense responses induced by a polyphagous herbivore in some of its host plants as well as some of its adaptation mechanisms to counter the effect of these defenses. I used the lepidopteran fall armyworm (FAW) Spodoptera frugiperda, and its host plants maize, Bermuda grass, rice and tomato as a model system. The FAW comprises two host strains that are associated with different host plants in field conditions; the corn strain is mainly associated with maize, while the rice strain is mostly associated with forage grasses and rice. I specifically tested the presence of intraspecific differences in plant defense induction by the FAW strains and the composition of their caterpillar saliva. I also investigated the effect of caterpillar-associated gut bacteria on the modulation of defense responses in different hosts. In addition, I documented morphological and developmental adaptations of the FAW larvae to cope with their host structural defenses. The results of this study show that feeding by the FAW strains induced different defense responses in maize and Bermuda grass; this plant defense induction was associated with differences in the caterpillar saliva. The saliva of the FAW strains also has divergent protein profiles and differing expression of several salivary proteins. In addition, the saliva of the FAW contains non-protein compounds that actively regulate defenses in different hosts; these include several phytohormones and other presumptive small molecules. During feeding, the FAW larvae also secrete small amounts of regurgitant, I identified two bacteria isolates in the caterpillar oral secretions that modulated defense responses in tomato and maize plants. In addition, feeding by this insect induced the production of glandular trichomes in tomato and the deposition of silica in maize and rice plants. As adaptive strategies to feed on Bermuda grass and rice, the FAW larvae increased their head size to house larger mandibular muscles and potentially increase the biting force needed to feed on tough leaves. I conclude that FAW feeding modulates the induction of plant biochemical and physical defenses, which in turn induced plastic physiological and morphological changes in this insect species. The results of this dissertation highlight the importance of insect physiological and morphological plastic adaptations as means to feed on different host plants.
Author: Alain Goossens
Publisher: Humana
ISBN: 9781493960132
Category : Science
Languages : en
Pages : 0
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Book Description
It is now well established that jasmonates, originally identified as the major component of jasmine scent, play a universal role in the plant kingdom and are involved in the regulation of diverse aspects of plant biology, including growth, development, metabolism, and interaction with the environment. In Jasmonate Signaling: Methods and Protocols, experts in the field aim to unite powerful emerging omics platforms with a number of key reductionist approaches to form a comprehensive collection of tools and protocols. The detailed chapters in this book embrace physiological, environmental, molecular, omics, and bioinformatics approaches that allow dissecting jasmonate actions in the model species Arabidopsis thaliana or in other plants. Written in the highly successful Methods in Molecular Biology series format, chapters feature introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, along with tips on troubleshooting and avoiding known pitfalls. Authoritative and cutting-edge, Jasmonate Signaling: Methods and Protocols will empower interested researchers to dissect all steps of jasmonate signaling and the processes they modulate.
Author: Richard Karban
Publisher: University of Chicago Press
ISBN: 0226424979
Category : Science
Languages : en
Pages : 332
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Book Description
Plants face a daunting array of creatures that eat them, bore into them, and otherwise use virtually every plant part for food, shelter, or both. But although plants cannot flee from their attackers, they are far from defenseless. In addition to adaptations like thorns, which may be produced in response to attack, plants actively alter their chemistry and physiology in response to damage. For instance, young potato plant leaves being eaten by potato beetles respond by producing chemicals that inhibit beetle digestive enzymes. Over the past fifteen years, research on these induced responses to herbivory has flourished, and here Richard Karban and Ian T. Baldwin present the first comprehensive evaluation and synthesis of this rapidly developing field. They provide state-of-the-discipline reviews and highlight areas where new research will be most productive. Their comprehensive overview will be welcomed by a wide variety of theoretical and applied researchers in ecology, evolutionary biology, plant biology, entomology, and agriculture.
