Bibliografías temáticas / Non-host plants

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Literatura académica sobre el tema "Non-host plants"

Autor: Grafiati

Publicado: 11 de marzo de 2023

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Artículos de revistas sobre el tema "Non-host plants"

Morley, Kate, Stan Finch y Rosemary H. Collier. "Companion planting - behaviour of the cabbage root fly on host plants and non-host plants". Entomologia Experimentalis et Applicata 117, n.º 1 (octubre de 2005): 15–25. http://dx.doi.org/10.1111/j.1570-7458.2005.00325.x.

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Schafer, W. y O. C. Yoder. "Organ specificity of fungal pathogens on host and non-host plants". Physiological and Molecular Plant Pathology 45, n.º 3 (septiembre de 1994): 211–18. http://dx.doi.org/10.1016/s0885-5765(05)80078-5.

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Bains, S. S. y H. S. Dhaliwal. "Production of Neovossia indica sporidia on host and non-host plants". Plant and Soil 126, n.º 1 (agosto de 1990): 85–89. http://dx.doi.org/10.1007/bf00041372.

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Li, Hua, Xintian Ge, Shiue Han, Krishnapillai Sivasithamparam y Martin John Barbetti. "Histological responses of host and non-host plants to Hyaloperonospora parasitica". European Journal of Plant Pathology 129, n.º 2 (17 de septiembre de 2010): 221–32. http://dx.doi.org/10.1007/s10658-010-9664-3.

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Keith, Ronald C., Lisa M. W. Keith, Gustavo Hernández-Guzmán, Srinivasa R. Uppalapati y Carol L. Bender. "Alginate gene expression by Pseudomonas syringae pv. tomato DC3000 in host and non-host plants". Microbiology 149, n.º 5 (1 de mayo de 2003): 1127–38. http://dx.doi.org/10.1099/mic.0.26109-0.

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Pseudomonas syringae produces the exopolysaccharide alginate, a copolymer of mannuronic and guluronic acid. Although alginate has been isolated from plants infected by P. syringae, the signals and timing of alginate gene expression in planta have not been described. In this study, an algD : : uidA transcriptional fusion, designated pDCalgDP, was constructed and used to monitor alginate gene expression in host and non-host plants inoculated with P. syringae pv. tomato DC3000. When leaves of susceptible collard plants were spray-inoculated with DC3000(pDCalgDP), algD was activated within 72 h post-inoculation (p.i.) and was associated with the development of water-soaked lesions. In leaves of the susceptible tomato cv. Rio Grande-PtoS, algD activity was lower than in collard and was not associated with water-soaking. The expression of algD was also monitored in leaves of tomato cv. Rio Grande-PtoR, which is resistant to P. syringae pv. tomato DC3000. Within 12 h p.i., a microscopic hypersensitive response (micro-HR) was observed in Rio Grande-PtoR leaves spray-inoculated with P. syringae pv. tomato DC3000(pDCalgDP). As the HR progressed, histochemical staining indicated that individual bacterial cells on the surface of resistant tomato leaves were expressing algD. These results indicate that algD is expressed in both susceptible (e.g. collard, tomato) and resistant (Rio Grande-PtoR) host plants. The expression of algD in an incompatible host–pathogen interaction was further explored by monitoring transcriptional activity in leaves of tobacco, which is not a host for P. syringae pv. tomato. In tobacco inoculated with DC3000(pDCalgDP), an HR was evident within 12 h p.i., and algD expression was evident within 8-12 h p.i. However, when tobacco was inoculated with an hrcC mutant of DC3000, the HR did not occur and algD expression was substantially lower. These results suggest that signals that precede the HR may stimulate alginate gene expression in P. syringae. Histochemical staining with nitro blue tetrazolium indicated that the superoxide anion () is a signal for algD activation in planta. This study indicates that algD is expressed when P. syringae attempts to colonize both susceptible and resistant plant hosts.

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Ballabeni, Pierluigi y Martine Rahier. "Performance of leaf beetle larvae on sympatric host and non-host plants". Entomologia Experimentalis et Applicata 97, n.º 2 (noviembre de 2000): 175–81. http://dx.doi.org/10.1046/j.1570-7458.2000.00728.x.

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Koenig, Christopher, Anne Bretschneider, David G. Heckel, Ewald Grosse-Wilde, Bill S. Hansson y Heiko Vogel. "The plastic response of Manduca sexta to host and non-host plants". Insect Biochemistry and Molecular Biology 63 (agosto de 2015): 72–85. http://dx.doi.org/10.1016/j.ibmb.2015.06.001.

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El-Atrach, F., H. Vierheilig y J. A. Ocampo. "Influence of non-host plants on vesicular-arbuscular mycorrhizal infection of host plants and on spore germination". Soil Biology and Biochemistry 21, n.º 1 (enero de 1989): 161–63. http://dx.doi.org/10.1016/0038-0717(89)90026-6.

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Hafez, Yaser M. "A Pivotal Role of Reactive Oxygen Species in Non-Host Resistance Mechanisms in Legume and Cereal Plants to the Incompatible Pathogens". International Journal of Phytopathology 4, n.º 1 (2 de mayo de 2015): 43–53. http://dx.doi.org/10.33687/phytopath.004.01.1176.

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Most of plants under normal conditions are resistant to most of the incompatible pathogens (viral, fungal and bacterial infections). This is called ״non-host resistance (NHR) phenomenon״. Till now it is not clear the non-host resistance mechanisms. As a result of inoculation of legume (pea and soybean) and cereal (barley and wheat) plants with compatible and incompatible pathogens, strong resistance symptoms were observed in the non-host/incompatible pathogen combinations as compared with host/compatible pathogen combinations which showed severe infection (susceptibility). Levels of reactive oxygen species (ROS) mainly hydrogen peroxide (H2O2) and superoxide (O2.-) were significantly increased early 6, 12, 24 and 36 hours after inoculation (hai) in the non-host plants as compared with host plants. Interestingly enough that the activities of the antioxidant enzymes such as catalase (CAT), dehydroascorbate reductase (DHAR) and peroxidase (POX) were not significantly increased at the same early time 6 - 36 hai in the non-host plants. However, these enzymes were significantly increased later on 48, 72 and 96 dai in the non-host plants as compared with host plants. It seems that early accumulation of H2O2 and O2.- could have a dual roles, first role is inhibiting or killing the pathogens early in the non-host plants, second immunization of the non-host plants by stimulating the activities of the antioxidant enzymes later on which thereby, neutralize the harmful effect of ROS and consequently suppressing disease symptoms. The author recommends giving more attention to these new mechanisms of non-host resistance particularly in relation to ROS levels and antioxidant activities which are very important for plant breeders and useful for finding alternative control strategies as well.

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Calatayud, P. A., Y. Rahbé, W. F. Tjallingii, M. Tertuliano y B. Rü. "Electrically recorded feeding behaviour of cassava mealybug on host and non-host plants". Entomologia Experimentalis et Applicata 72, n.º 3 (septiembre de 1994): 219–32. http://dx.doi.org/10.1111/j.1570-7458.1994.tb01821.x.

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Tesis sobre el tema "Non-host plants"

Abourghiba, Taher Yonis. "Comparative analysis of the impacts of arbuscular mycorrhizal fungi on 'host' and 'non-host' plants". Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422182.

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Gammelgård, Elin. "Interactions of potato virus A with host plants : recombination, gene silencing and non-hypersensitive resistance /". Uppsala : Dept. of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/2007111.pdf.

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Noel, Tanya C. "Interaction of Rhizobium leguminosarum tryptophan and adenosine auxotrophs with host plants and non-legumes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34689.pdf.

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Friberg, Hanna. "Persistence of Plasmodiophora brassicae : influence of non-host plants, soil fauna and organic material /". Uppsala : Dept. of Entomology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/2005115.pdf.

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Schwarzkopf, Alexander [Verfasser], Jonathan [Gutachter] Gershenzon, Rolf G. [Gutachter] Beutel y Jean-Christophe [Gutachter] Simon. "Electrophysiological localization of plant factors affecting pea aphid (Acyrthosiphon pisum) compatibility to host and non-host plants / Alexander Schwarzkopf ; Gutachter: Jonathan Gershenzon, Rolf G. Beutel, Jean-Christophe Simon". Jena : Friedrich-Schiller-Universität Jena, 2017. http://d-nb.info/1177600404/34.

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Beswetherick, John T. "An ultrastructural study of host and non-host resistance reactions in plant cells". Thesis, Open University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292658.

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Cattaneo, Alberto Maria. "Unveiling sensory mechanisms for the control of two insect pests: from behaviour to molecular interactions". Doctoral thesis, country:IT, 2015. http://hdl.handle.net/10449/29924.

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Pest control strategies targeting insect olfaction represent a promising venue for control of tortricid insects (Lepidoptera: Tortricidae). Among tortricids, the grapevine moth Lobesia botrana (Denis and Schiffermüller) and the codling moth Cydia pomonella (L.) are serious pests for worldwide production of fruit crops. We employed several approaches to the olfactory system, from electrophysiological and behavioral studies in the grapevine moth, to bioinformatic and molecular studies of olfactory sensory proteins in the codling moth. At the receptor level, we studied both the Olfactory Receptors (ORs), the most common class of sensory proteins mediating detection of odors in insect antennae, and the Transient Receptor Potential (TRP) channels, a novel family of receptor, that recently were also found in the antennae of lepidopterous species. We demonstrated electrophysiological and behavioral responses of the grapevine moth to volatiles emitted by a non-host, Perilla frutescens, previously known to activate TRPs in the rat, Rattus norvegicus. In the codling moth, we characterized a novel TRP channel (TRPA pyrexia-like) and we confirmed activation of its human orthologue to the same non-host compounds active on the olfactory system of the grapevine moth. ORs were heterologously expressed in vivo and in vitro, for identification of their ligands among host and non-host plant volatiles and pheromones (deorphanization). Among several ORs of codling moth, we deorphanized a candidate pheromone receptor (PR) to plant synergists, an OR to non-host volatiles and another PR candidate to a pheromone antagonist of the insect. Our study thus opens for refinement of existing pest control, or novel applications. The behavioral response of the grapevine moth to volatiles from a nonhost plant, and the identification of a novel TRP channel in the codling moth may have perspectives for application in agriculture, targeting the somatosensory system of these tortricids. The evolutionary implications of the responses of the human orthologue of TRPA pyrexia-like to volatiles active on the grapevine moth olfactory system could imply a large degree of conservation of the receptor function. In the codling moth, identification of synergist and antagonist ligands for candidate PRs and deorphanization of an OR to non-host plant volatiles suggest a possible role of these receptors in reproductive and ecological isolation. This could lead to further refinement of existing semiochemicalbased control techniques, by enabling a better understanding of mate- and host-finding in this species.

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Chigurupati, Pavan Chandra. "Role of SABP2 in Tobacco Non-Host Resistance". Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1393.

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Plant innate immunity is activated upon pathogen attack by recognizing their avirulent (avr) genes by Resistant (R) genes leading to R-gene resistance or host resistance. Another form of innate immunity is non-host resistance that is exhibited by a given plant species to most strains of a microbial species. R-gene resistance activates salicylic acid (SA) that is synthesized from methyl salicylic acid (MeSA) by Salicylic Acid Binding Protein 2 (SABP2). It was hypothesized that SABP2 plays the similar role in non-host resistance also. Growth experiments and non-host related gene analysis experiments were conducted on tobacco plants using P.s tabaci and P.s. phaseolicola that are host and non-host pathogens on tobacco respectively. Tobacco control plant C3 that expresses SABP2 and 1-2 that is RNAi silenced in SABP2 expression were used in this study. Results suggest that SABP2 may not have any significant role in tobacco non-host resistance.

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Mauchline, Alice Louise. "Behavioural and chemical ecology of Meligethes aeneus : effects of non-host plant volatiles". Thesis, Open University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396333.

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Zhang, Qing-He. "Olfactory recognition and behavioural avoidance of angiosperm non-host volatiles by conifer bark beetles /". Alnarp : Swedish Univ. of Agricultural Sciences (Sveriges lntbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5789-0.pdf.

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Libros sobre el tema "Non-host plants"

Taberlet, Pierre, Aurélie Bonin, Lucie Zinger y Eric Coissac. Host-associated microbiota. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198767220.003.0016.

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DNA-based approaches have enabled the multifaceted role of microbes for the fitness and performance of their host to be revealed. The increasing recognition of the crucial role of microorganisms for the fitness and performance of plants and animals has led to the concepts of holobiont (i.e., a host and its microbiota), and hologenome (i.e., the collective genomes of a holobiont). Here a brief review is provided of the advances that have been made in this field by using DNA-based approaches. Chapter 16 “Host-associated microbiota” summarizes this area of research by presenting past and recent major findings, as well as new research avenues for unraveling host-microbiota interactions in non-model animals and plants.

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Lloyd, Sheelagh y Lord Soulsby. Other non-Fasciola trematode infections. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780198570028.003.0063.

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A large variety of trematodes result in millions of fish- and other food-borne human infections annually. These are mostly in Asia but some more widespread. Man may be an important or occasional definitive host acquiring infection from eating fish, frogs, snails, crustaceans, ants, and water plants, and from drinking water. Consumption of these raw/undercooked produces human infection. Adult flukes occur in the biliary system, intestine, lungs, and occasionally ectopically.

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McAuliffe, Jane. The Qur'an. Oxford University Press, 2020. http://dx.doi.org/10.1093/wentk/9780190867683.001.0001.

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Millions of non-Muslims know the name of the Muslim scripture, whether it is written as “Qur’an” or “Quran” or “Koran.” But for most, that is all they know. Many have fallen victim to the mass of misinformation that circulates about the Qur’an. Others may have tried to read the Qur’an, but the text itself is tough to decipher. With no sense of context, chronology, or interpretive history, many would-be readers of the Qur’an quickly give up the effort. As for those trying to find out what the Qur’an says about any particular subject or issue, they, too, soon discover that this is not a simple or straightforward undertaking. A clear, concise introduction to the holy book that guides the lives of 1.6 billion people on our planet, this brief volume opens the world of the Qur’an to interested readers who want to know where this scripture came from and how it has achieved a profound influence in today’s world. Writing in an easy-to-read question-and-answer format, Jane McAuliffe, one of the world’s foremost scholars of the Qur’an, introduces readers to this important text by discussing its origins, structure, themes, interpretations, and what it has to say about a host of critical contemporary issues. Where did the Qur’an come from? Do Muslims believe that the Qur’an is God’s own word? How do Muslims study the Qur’an? What does the Qur’an say about God? About family? About ethics? About violence? By answering the questions that many people have about the Qur’an and its role in Muslim faith, this book offers an invaluable resource for anyone who is curious about one of the world’s most important faiths.

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Capítulos de libros sobre el tema "Non-host plants"

Li, Hua, Xintian Ge, Shiue Han, Krishnapillai Sivasithamparam y Martin John Barbetti. "Histological responses of host and non-host plants to Hyaloperonospora parasitica". En The Downy Mildews - Biology, Mechanisms of Resistance and Population Ecology, 89–100. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-94-007-1281-2_7.

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Grondeau, Catherine y Regine Samson. "Effect of Host Genotype and Non-Host Plants on Epiphytic Life of Pseudomonas syringae pv. pisi". En Developments in Plant Pathology, 22–25. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5472-7_4.

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Prell, Hermann H. y Peter Day. "Basic Resistance: The Absence of Parasitism of Non-Host Plants by Phytopathogenic Fungi". En Plant-Fungal Pathogen Interaction, 41–49. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-662-04412-4_6.

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Kotanen, Peter M. "Direct and indirect effects of herbivores influencing plant invasions." En Plant invasions: the role of biotic interactions, 226–40. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0226.

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Abstract Non-native plants rarely escape damage by herbivores. Instead, upon arrival in a new region, they begin to acquire new enemies, replacing those they have lost during their migration. These herbivores can include both natives to the new region and species that have themselves been accidentally or deliberately introduced from elsewhere, potentially including examples originating from the invader's original range. Shifts of new enemies from other hosts can occur over a range of timescales, depending in part on whether evolutionary change is required, but are likely to be faster for plants that are widespread and phylogenetically related to a herbivore's original host, and faster for generalist herbivores than for specialists. The occurrence of herbivores is not necessarily uniform across an invader's range; instead, they may be less diverse or abundant in host populations that are geographically or ecologically marginal, though existing evidence is mixed. Collectively, these new suites of herbivores can affect the growth and fitness of invaders, both directly by damaging them and indirectly by attacking their competitors. Studies comparing the demographic consequences of herbivory for successful vs unsuccessful invaders may help to clarify how often such impacts limit invasiveness. The view that an invader enters 'enemy-free' space is inaccurate; instead, persistence and spread of non-native plants often may be affected by the novel and changing assemblage of herbivores that they acquire within their new distribution.

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Tanpure, R. S., K. R. Kondhare, V. Venkatesh, V. S. Gupta, R. S. Joshi y A. P. Giri. "Non-host Armor Against Insect: Characterization and Application of Capsicum annuum Protease Inhibitors in Developing Insect Tolerant Plants". En Genetically Modified Crops, 85–110. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5932-7_4.

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Hill, Martin P. y Julie A. Coetzee. "How can progress in the understanding of antagonistic interactions be applied to improve biological control of plant invasions?" En Plant invasions: the role of biotic interactions, 363–76. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0363.

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Abstract Classical biological control has been used as a management tool for invasive non-native plant species globally for over 200 years. There have been some very successful programmes, most notably on waterweeds, cacti and seed reduction in perennial trees. Seventy per cent of agents released have established in at least one instance, and 66% of the targeted invasive species have showed some level of control. However, some programmes have failed to meet expectations, for example on Lantana camara. The most commonly cited reasons for the failure of establishment or limited efficacy of biological control agents are unsuitable climatic conditions and genotype incompatibility. We propose that antagonistic biotic interactions play a significant role in the outcomes of weed biological control programmes. Induced plant defences (physical and chemical) that can be mounted rapidly by the invasive non-native plants can result in the reduction in agent populations after initial attack. Rapid induction of plant defences have been implicated in the lack of long-term establishment of the agent Falconia intermedia that showed great initial promise against the widespread invasive shrub L. camara. Host range expansion by native natural enemies onto biological control agents have also been shown to reduce population growth of agents. Finally, competition from indigenous plant species aids invasive alien plant population reduction in the presence of herbivory. All three factors have been poorly studied and further work is needed to better explain the outcomes of weed biological control programmes.

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Gao, Shang y Hailing Jin. "Host Small RNAs and Plant Innate Immunity". En Non Coding RNAs in Plants, 21–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19454-2_2.

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Ride, J. P. "Non-Host Resistance to Fungi". En Mechanisms of Resistance to Plant Diseases, 29–61. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5145-7_3.

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Fraser, R. S. S. "Host-Range Control and Non-Host Immunity to Viruses". En Mechanisms of Resistance to Plant Diseases, 13–28. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5145-7_2.

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Aguilera, Paula, Fernando Borie, Alex Seguel y Pablo Cornejo. "How Does the Use of Non-Host Plants Affect Arbuscular Mycorrhizal Communities and Levels and Nature of Glomalin in Crop Rotation Systems Established in Acid Andisols?" En Fungal Biology, 147–58. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-15228-4_7.

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Actas de conferencias sobre el tema "Non-host plants"

Apine, Inga y Uģis Piterāns. "FIRST RECORDS OF AZALEA SAWFLY NEMATUS LIPOVSKY SMITH, 1974 (HYMENOPTERA: TENTHREDINIDAE) IN LATVIA". En GEOLINKS Conference Proceedings. Saima Consult Ltd, 2021. http://dx.doi.org/10.32008/geolinks2021/b2/v3/11.

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Invasive non-native insect species are well-known threat to both local and introduced plant species in Europe. With increasing global trade and effects of climate change it is expected these alien species will continue to expand their distribution areas. One such non-native species is azalea sawfly Nematus lipovskyi Smith, 1974 (Hymenoptera: Tenthredinidae) that feeds on deciduous Rhododendron spp. This species is known to occur in the USA and was found in the Czech Republic for the first time in Europe in 2010. We report the first findings of this species in Latvia that were made based of field observations in the period of 2018-2020. The current known status of the species in Latvia is presented. Our observations of damage caused by sawfly larvae are summarized. Host plants used by sawfly larvae are listed – we note Rhododendron albrechtii as a host plant of this species for the first time. The possible pathways of its introduction and the overall importance of our findings in context with other non-native species expansions are briefly discussed.

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Guro, P., V. Safronova, A. Sazanova, I. Kuznetsova, A. Belimov, V. Yakubov, E. Chirak, A. Afonin, E. Andronov y I. Tikhonovich. "Rhizobial microsymbionts of the narrowly endemic Oxytropis species growing in Kamchatka possess a set of genes that are associated with T3SS and T6SS secretion systems and can affect the development of symbiosis". En 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.099.

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A collection of rhizobial strains isolated from root nodules of the narrowly endemic legume species Oxytropis erecta, O. anadyrensis, O. kamtschatica and O. pumilio growing on the Kamchatka Peninsula (Russian Federation) was obtained. Analysis of the 16S rRNA gene sequence showed a significant diversity of isolates belonging to the families Rhizobiaceae (Rhizobium), Phyllobacteriaceae (Mesorhizobium, Phyllobacterium) and Bradyrhizobiaceae (Bosea, Tardiphaga). Pairs of taxonomically different strains in various combinations were isolated from some nodules of Oxytropis plants. Plant nodulation assays showed that only strains belonging to the genus Mesorhizobium (M. jarvisii, M. loti and M. huakuii) could form nitrogen-fixing nodules. The nitrogen-fixing activity of the strains was more associated with the host plant than with the species of strains. The whole genome sequences analysis showed that the strains M. loti 582 and M. huakuii 583 possessed symbiotic genes necessary for the formation of effective symbiosis and grouped into Sym-clusters. In contrast, the strain T. robiniae 581 had only a reduced number of fix genes, while the strains Phyllobacterium sp. 628 and R. lusitanum 629 possesed only individual symbiotic genes, which obviously did not participate in the formation of nodules. It was also stated that the strains M. loti 582 and M. huakuii 583 had a significantly larger set of genes related to the secretion systems T3SS and T6SS that can affect the host specificity of strains, compared with 6 commercial strains used as reference. These two strains formed nodules of two types (typical elongated and atypical rounded) on Oxytropis plants. We suggest that a possible cause of the observed phenomenon is the availability of different nodulation strategies in these strains (dependent and independent of Nod-factors). Thus, as a result of studying the collection of strains isolated from the narrow endemic species of Kamchatka Oxytropis, interesting objects were selected to study the functions of the T3SS and T6SS genes, and their role in the development of rhizobia-legume symbiosis. The prospects of using strains with gene systems for both symbiotic and non-symbiotic nodulation to enhance the efficiency of plant-microbe interactions by expanding the host specificity and increasing the efficiency of nodulation are discussed.

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Cheng, Kuok, Eunsoo Yang, Chi Young Lee, Zane Ricks, Viljar Palmre y Kwang Kim. "Fine-Tuned Polymer Nano-Composite Coatings for Use in Geothermal Plants". En ASME 2011 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2011. http://dx.doi.org/10.1115/smasis2011-5012.

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Often times erosion, corrosion, and fouling by scale deposition are primary issues for geothermal-fluid-wetted process equipment. In particular, wet heat exchangers used in geothermal power plants must deal with scale deposition. Previously, a surface-coating of polytetrafluoroethylene (PTFE) was considered to provide a non-stick surface. However, intrinsically poor thermal conductivity of PTFE, along with its poor abrasion resistance and weak adhesion to metal substrate, turns out to be a serious concern for engineering use. In this paper, we report a fine-tuned nano-composite by incorporating PTFE/Carbon-nanotube (CNT) into the polyphenylene surfide (PPS) host matrix. PPS is a thermoplastic polymer exhibiting outstanding high-temperature stability, excellent flame resistance, and good chemical resistance. By adding PTFE/CNTs into a PPS matrix, a superhydrophobic surface can also be created by contemplating the chemical composition of the surface material and the cooperative effect of nano-micro structures at the surface. Furthermore, carefully engineered superhydrophobic surfaces can create so-called “dropwise condensation [1]” which can dramatically enhance steam condensation heat transfer. We report the performance results of such nanocomposites regarding steam condensation, along with other surface characteristics. It is our anticipation that, with proper treatment, PTFE/CNT blended PPS can be widely adopted for use in high performance heat exchangers in geothermal industries.

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Burakov, B., V. Gribova, A. Kitsay, M. Ojovan, N. C. Hyatt y M. C. Stennett. "Synthesis of Crystalline Ceramics for Actinide Immobilisation". En The 11th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2007. http://dx.doi.org/10.1115/icem2007-7047.

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Methods for the synthesis of ceramic wasteforms for the immobilization of actinides are common to those for non-radioactive ceramics: hot uniaxial pressing (HUP); hot isostatic pressing (HIP); cold pressing followed by sintering; melting (for some specific ceramics, such as garnet/perovskite composites). Synthesis of ceramics doped with radionuclides is characterized with some important considerations: all the radionuclides should be incorporated into crystalline structure of durable host-phases in the form of solid solutions and no separate phases of radionuclides should be present in the matrix of final ceramic wasteform; all procedures of starting precursor preparation and ceramic synthesis should follow safety requirements of nuclear industry. Synthesis methods that avoid the use of very high temperatures and pressures and are easily accomplished within the environment of a glove-box or hot cell are preferable. Knowledge transfer between the V. G. Khlopin Radium Institute (KRI, Russia) and Immobilisation Science Laboratory (ISL, UK) was facilitated in the framework of a joint project supported by UK Royal Society. In order to introduce methods of precursor preparation and ceramic synthesis we selected well-known procedures readily deployable in radiochemical processing plants. We accounted that training should include main types of ceramic wasteforms which are currently discussed for industrial applications.

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Cai, Ting-Ting, Xiang-Qun Lin, Pu-Xian Zhang, Kun Zhang, Liang Wang y Min Ye. "Behavioral Responses of Aphid (Myzus Persicae) to Volatiles from Non-Host Plant Lavender (Lavandula Angustifolia)". En 2nd Annual International Conference on Energy, Environmental & Sustainable Ecosystem Development (EESED 2016). Paris, France: Atlantis Press, 2017. http://dx.doi.org/10.2991/eesed-16.2017.42.

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Eriksson, Leif G. "Lessons Learned at the Waste Isolation Pilot Plant: Share, Listen, and Learn to Earn Stakeholder Acceptance". En ASME 2001 8th International Conference on Radioactive Waste Management and Environmental Remediation. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/icem2001-1254.

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Abstract On March 26, 1999, the United States (U.S.) Department of Energy (DOE) opened the nation’s first deep geological disposal system (repository) for long-lived radioactive wastes/materials (LLRMs) at the Waste Isolation Pilot Plant (WIPP) site, New Mexico, United States of America (USA). The opening of WIPP embodies gradually achieved acceptance, both local and global, on scientific, institutional, regulatory, political, and public levels. In the opinion of the author, five significant determinants for the successful siting, certification, and acceptance of WIPP, were the existence of: • A willing and supportive host community; • A strong, independent regulator; • A regulatory framework widely perceived to (over)protect public health and the environment; • A structurally simple, old, stable, host-rock with excellent radionuclide containment and isolation characteristics; and • An open siting, site characterization, repository development, certification and recertification process with regularly scheduled opportunities for information exchanges with affected and interested parties, including a) prompt responses to non-DOE concerns and b) transparency/traceability of external-input into, and the logic behind, the DOE’s decision-making process. The nation’s and the world’s next deep geological repository for LLRMs is currently scheduled to open in 2010. As follows, in addition to providing a national solution to safe disposal of LLRMs, the opening and continued safe operation of WIPP provides an international role model that effectively dispels the global myth that LLRMs cannot be safely disposed in a deep geological repository.

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Piyaket, Ram, Ilkan Cokgor, Frederick B. McCormick, Sadik Esener, Alexander S. Dvornikov y Peter M. Rentzepis. "Two-photon absorption based optical recording in organic planar waveguide". En Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.wgg.5.

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Two-photon absorption based three-dimensional (3-D) memories have been investigated and demonstrated over the last years, providing potentials for high memory densities and parallel access for fast data rates. Figure 1 illustrates the basic principle by which information is stored and retrieved in these 3-D memories. Two photons with appropriate combined energy (for example, λ = 1064 and 532 nm) are introduced into the memory and are absorbed simultaneously by the memory material which consists of spirobenzopyran (SP) in a PMMA host matrix).1 The simultaneous absorption of the two photons by the photochromic molecule results in a bond dissociation transforming it into a new form with different properties, including the absorption spectrum as shown in Fig. 1. These two different molecular forms are defined as the non-written and written forms of the memory. When properly excited, the new molecular form emits fluorescence which can be detected during the read-out process. The peak fluorescence occurs at 660 nm.

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Beuhler, Allyson J., David A. Wargowski, Kenneth D. Singer, Tony Kowalczyk, Paul A. Cahill y Carl Seager. "Polyimide Optical Waveguides". En Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/otfa.1993.fa.1.

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Aromatic polyimides are of interest for integrated optics due to a combination of high thermal stability and easy processibility into planar structures. Polyimides can withstand chip attach and package assembly temperatures and are resistant to corrosive etchants and cleaning solvents making them compatible with a variety of substrates and metallization schemes. Waveguides from polyimide can be patterned by photobleaching1 or etching2 using standard semiconductor or printed circuit board technology and equipment. Polyimide properties are easily engineered by co-polymerization with co-diamines or dianhydrides to tailor the refractive indices or incorporate photosensitivity. Electro-optic polyimides have been demonstrated that incorporate non-linear optical chromophores by guest-host doping.3

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Satish, D. "Ionization Potentials of Nucleic Acid Intercalators". En Functional Materials and Applied Physics. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901878-12.

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Abstract. Nucleic acid based electronic devices have attracted particular interest over the past two decades due to its ability of long-range charge transport and self-assembly. The π-π interactions of the stacked bases are believed to be responsible for the long-range charge transport. The insertion of intercalators could alter electronic structure of the host nucleic acids which may influence the charge transport through the nucleic acid. The influence of intercalators on charge transport through the host nucleic acids largely depends on ionization potentials of the intercalators. Therefore, in this work we intend to determine vertical and adiabatic ionization potentials of the nucleic acid intercalators by using density functional theory calculations using Gaussian 16 package. We also explore the role of solvent and discuss the significance of ionization potential values in comparison with the ionization potential values of nucleic acid bases. Ionization Potential values of these intercalators range from 7.67 eV to 11.12 eV and 4.5 eV to 6.46 eV in vacuum and aqueous medium, respectively. Daunomycin is found to have lowest ionization potential value in vacuum as well as in aqueous medium. On the other hand, Proflavine (Anthraquinone) has highest ionization potential value in vacuum (aqueous medium). Non-planar intercalators exhibit distinct vertical and adiabatic ionization potential values and decrease drastically upon solvation.

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Enikov, Eniko T. y Estelle Eke. "Teaching Classical Control System Course With Portable Student-Owned Mechatronic Kits". En ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-86700.

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Teaching classical controls systems design to mechanical engineering students presents unique challenges. While most mechanical engineering programs prepare students to be well-versed in the application of physical principles and modeling aspects of physical systems, implementation of closed loop control and system-level analysis is lagging. It is not uncommon that students report difficulty in conceptualizing even common controls systems terms such as steady-state error and disturbance rejection. Typically, most courses focus on the theoretical analysis and modeling, but students are left asking the questions…How do I implement a phase-lead compensator? …What is a non-minimum phase system? This paper presents an innovative approach in teaching control systems design course based on the use of a low-cost apparatus that has the ability to directly communicate with MATLAB and its Simulink toolbox, allowing students to drag-and-drop controllers and immediately test their effect on the response of the physical plant. The setup consists of a DC micro-motor driving a propeller attached to a carbon-fiber rod. The angular displacement of the rod is measured with an analog potentiometer, which acts as the pivot point for the carbon fiber rod. The miniature circuit board is powered by the USB port of a laptop and communicates to the host computer using the a virtual COM port. MATLAB/Simulink communicates to the board using its serial port read/write blocks to command the motor and detect the deflection angle. This presentation describes a typical semester-long experimental protocol facilitated by the low-cost kit. The kit allows demonstration of classical PID, phase lead and lag controllers, as well as non-linear feedback linearization techniques. Comparison between student gains before and after the introduction of the mechatronic kits are also provided.

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Informes sobre el tema "Non-host plants"

Zhao, Bingyu, Saul Burdman, Ronald Walcott y Gregory E. Welbaum. Control of Bacterial Fruit Blotch of Cucurbits Using the Maize Non-Host Disease Resistance Gene Rxo1. United States Department of Agriculture, septiembre de 2013. http://dx.doi.org/10.32747/2013.7699843.bard.

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The specific objectives of this BARD proposal were: (1) To determine whether Rxol can recognize AacavrRxo1 to trigger BFB disease resistance in stable transgenic watermelon plants. (2) To determine the distribution of Aac-avrRxo1 in a global population of Aae and to characterize the biological function of Aac-avrRxo1. (3) To characterize other TIS effectors of Aae and to identify plant R gene(s) that can recognize conserved TIS effectors of this pathogen. Background to the topic: Bacterial fruit blotch (BFB) of cucurbits, caused by Acidovorax avenae subsp. citrulli (Aae), is a devastating disease that affects watermelon (Citrullus lanatus) and melon (Cucumis melo) production worldwide, including both Israel and USA. Two major groups of Aae strains have been classified based on their virulence on host plants, genetics and biochemical properties. Thus far, no effective resistance genes have been identified from cucurbit germplasm. In this project, we assessed the applicability of a non-host disease resistance gene, Rxol, to control BFB in watermelon. We also tried to identify Aae type III secreted (TIS) effectors that can be used as molecular probes to identify novel disease resistance genes in both cucurbits and Nieotianatabaeum. Major conclusions, solutions, achievements: We generated five independent transgenic watermelon (cv. Sugar Babay) plants expressing the Rxol gene. The transgenic plants were evaluated with Aae strains AAC001 and M6 under growth chamber conditions. All transgenic plants were found to be susceptible to both Aae strains. It is possible that watermelon is missing other signaling components that are required for Rxol-mediated disease resistance. In order to screen for novel BFB resistance genes, we inoculated two Aae strains on 60 Nieotiana species. Our disease assay revealed Nicotiana tabaeum is completely resistant to Aae, while its wild relative N. benthamiana is susceptible to Aae. We further demonstrated that Nieotiana benthamiana can be used as a surrogate host for studying the mechanisms of pathogenesis of Aae. We cloned 11 TIS effector genes including the avrRxolhomologues from the genomes of 22 Aae strains collected worldwide. Sequencing analysis revealed that functional avrRxol is conserved in group" but not group I Aae strains. Three effector genes- Aave_1548, Aave_2166 and Aave_2708- possessed the ability to trigger an HR response in N. tabacum when they were transiently expressed by Agrobaeterium. We conclude that N. tabacum carries at least three different non-host resistance genes that can specifically recognize AaeTIS effectors to trigger non-host resistance. Screening 522 cucurbits genotypes with two Aae strains led us to identify two germplasm (P1536473 and P1273650) that are partially resistant to Aae. Interestingly, transient expression of the TIS effector, Aave_1548, in the two germplasms also triggered HR-Iike cell death, which suggests the two lines may carry disease resistance genes that can recognize Aave_1548. Importantly, we also demonstrated that this effector contributes to the virulence of the bacterium in susceptible plants. Therefore, R genes that recognize effector Aave1548 have great potential for breeding for BFB resistance. To better understand the genome diversity of Aae strains, we generated a draft genome sequence of the Israeli Aae strain, M6 (Group I) using Iliumina technology. Comparative analysis of whole genomes of AAC001, and M6 allowed us to identify several effectors genes that differentiate groups I and II. Implications, both scientific and agricultural: The diversity of TIS effectors in group I and II strains of Aae suggests that a subset of effectors could contribute to the host range of group I and II Aae strains. Analysis of these key effectors in a larger Aae population may allow us to predict which cucurbit hosts may be at risk to BFB. Additionally, isolation of tobacco and cucurbit Rgenes that can recognize Aae type III effectors may offer new genetic resources for controlling BFB.

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Rodriguez, Russell J. y Stanley Freeman. Gene Expression Patterns in Plants Colonized with Pathogenic and Non-pathogenic Gene Disruption Mutants of Colletotrichum. United States Department of Agriculture, febrero de 2009. http://dx.doi.org/10.32747/2009.7592112.bard.

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Fungal plant pathogens are responsible for extensive annual crop and revenue losses throughout the world. To better understand why fungi cause diseases, we performed gene-disruption mutagenesis on several pathogenic Colletotrichum species and demonstrated that pathogenic isolates can be converted to symbionts expressing non-pathogenic lifestyles. One group of nonpathogenic mutants confer disease protection against pathogenic species of Col!etotrichum, Fusarium and Phytophthora; drought tolerance; and growth enhancement to host plants. These mutants have been defined as mutualists and disease resistance correlates to a decrease in the time required for hosts to activate defense systems when exposed to virulent fungi. A second group of non-pathogenic mutants did not confer disease resistance and were classified as commensals. In addition, we have demonstrated that wildtype pathogenic Colletotrichum species can express non-pathogenic lifestyles, including mutualism, on plants they colonize asymptomatically. We have been using wildtype and isogenic gene disruption mutants to characterize gene expression patterns in plants colonized with a pathogen, mutualist or commensal. The US group is contrasting genes expressed during colonization by mutuahstic and commensal mutants of C. magna and a pathogenic wildtype C. coccodes on tomato. The Israeli group is characterizing genes expressed during asymptomatic colonization of tomato by wildtype C. acutatum and a non-pathogenic mutant.To accomplish this we have been utilizing suppressive subtraction hybridization, microarray and sequencing strategies. The expected contribution of this research to agriculture in the US and Israel is: 1) understanding how pathogens colonize certain hosts asymptomatic ally will shed light on the ecology of plant pathogens which has been described as a fundamental deficiency in plant pathology; 2) identifying genes involved in symbiotically conferred disease resistance will help explain why and how pathogens cause disease, and may identify new candidate targets for developing genetically modified disease resistant crop plants.

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Aly, Radi, James H. Westwood y Carole L. Cramer. Novel Approach to Parasitic Weed Control Based on Inducible Expression of Cecropin in Transgenic Plants. United States Department of Agriculture, mayo de 2003. http://dx.doi.org/10.32747/2003.7586467.bard.

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Our overall goal was to engineer crop plants with enhanced resistance to Orobanche (broomrape) based on the inducible expression of sarcotoxin-like peptide (SLP). A secondary objective was to localize small proteins such as SLP in the host-parasite union in order to begin characterizing the mechanism of SLP toxicity to Orobanche. We have successfully accomplished both of these objectives and have demonstrated that transgenic tobacco plants expressing SLP under control of the HMG2 promoter show enhanced resistance to O. aegyptiaca and O. ramosa . Furthermore, we have shown that proteins much larger than the SLP move into Orobanche tubercles from the host root via either symplastic or apoplastic routes. This project was initiated with the finding that enhanced resistance to Orobanche could be conferred on tobacco, potato, and tomato by expression of SLP (Sarcotoxin IA is a 40-residue peptide produced as an antibiotic by the flesh fly, Sarcophaga peregrina ) under the control of a low-level, root-specific promoter. To improve the level of resistance, we linked the SLP gene to the promoter from HMG2, which is strongly inducible by Orobanche as it parasitizes the host. The resulting transgenic plants express SLP and show increased resistance to Orobanche. Resistance in this case is manifested by increased growth and yield of the host in the presence of the parasite as compared to non-transgenic plants, and decreased parasite growth. The mechanism of resistance appears to operate post-attachment as the parasite tubercles attached to the transgenic root plants turned necrotic and failed to develop normally. Studies examining the movement of GFP (approximately 6X the size of SLP) produced in tobacco roots showed accumulation of green fluorescence in tubercles growing on transformed plants but not in those growing on wild-type plants. This accumulation occurs regardless of whether the GFP is targeted to the cytoplasm (translocated symplastically) or the apoplastic space (translocated in xylem). Plants expressing SLP appear normal as compared to non-transgenic plants in the absence of Orobanche, so there is no obvious unintended impact on the host plant from SLP expression. This project required the creation of several gene constructs and generation of many transformed plant lines in order to address the research questions. The specific objectives of the project were to: 1. Make gene constructs fusing Orobanche-inducible promoter sequences to either the sarcotoxin-like peptide (SLP) gene or the GFP reporter gene. 2. Create transgenic plants containing gene constructs. 3. Characterize patterns of transgene expression and host-to-parasite movement of gene products in tobacco ( Nicotiana tabacum L.) and Arabidopsis thaliana (L.). 4. Characterize response of transgenic potato ( Solanum tuberosum L.) and tomato ( Lycopersicon esculentum Mill .) to Orobanche in lab, greenhouse, and field. Objectives 1 and 2 were largely accomplished during the first year during Dr. Aly's sabbatical visit to Virginia Tech. Transforming and analyzing plants with all the constructs has taken longer than expected, so efforts have concentrated on the most important constructs. Work on objective 4 has been delayed pending the final results of analysis on tobacco and Arabidopsis transgenic plants. The implications of this work are profound, because the Orobanche spp. is an extremely destructive weed that is not controlled effectively by traditional cultural or herbicidal weed control strategies. This is the first example of engineering resistance to parasitic weeds and represents a unique mode of action for selective control of these weeds. This research highlights the possibility of using this technique for resistance to other parasitic species and demonstrates the feasibility of developing other novel strategies for engineering resistance to parasitic weeds.

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Rodriguez, Russell y Stanley Freeman. Characterization of fungal symbiotic lifestyle expression in Colletotrichum and generating non-pathogenic mutants that confer disease resistance, drought tolerance, and growth enhancement to plant hosts. United States Department of Agriculture, febrero de 2005. http://dx.doi.org/10.32747/2005.7587215.bard.

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Fungal plant pathogens are responsible for extensive annual crop and revenue losses throughout the world. To better understand why fungi cause diseases, we performed gene-disruption mutagenesis on several pathogenic Colletotrichum species and demonstrated that pathogenic isolates can be converted to symbionts (mutualism, commensalism, parasitism) expressing non-pathogenic lifestyles. The objectives of this proposal were to: 1- generate crop-specific mutants by gene disruption that express mutualistic lifestyles, 2- assess the ability of the mutualists to confer disease resistance, drought tolerance, and growth enhancement to host plants, 3- compare fslm1 sequences and their genomic locations in the different species, and 4- document the colonization process of each Colletotrichum species.It was demonstrated that wildtype pathogenic Colletotrichum isolates, can be converted by mutation from expressing a pathogenic lifestyle to symbionts expressing non-pathogenic lifestyles. In the US, mutants of Colletotrichum were isolated by homologous gene disruption using a vector containing a disrupted FSlm1 sequence while in Israel, C. acutatum mutants were selected by restriction enzyme mediated integration (REMI) transformation. One group (US) of non-pathogenic mutants conferred disease protection against pathogenic species of Colletotrichum, Fusarium, and Phytophthora; drought tolerance; and growth enhancement to host plants. These mutants were defined as mutualists and disease resistance correlated to a decrease in the time required for hosts to activate defense systems when exposed to virulent fungi. The second group (Israel) of non-pathogenic mutants did not confer disease resistance and were classified as commensals. In addition, we demonstrated that wildtype pathogenic Colletotrichum species can express non-pathogenic lifestyles, including mutualism, on plants they colonize asymptomatically. The expected long term contribution of this research to agriculture in the US and Israel is threefold. Host-specific mutualists will be utilized in the various crops to confer (1) disease resistance to reduce dependence on chemical fungicides; (2) drought tolerance to reduce water consumption for irrigation; (3) growth enhancement to increase yields.

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Freeman, Stanley y Russell J. Rodriguez. The Interaction Between Nonpathogenic Mutants of Colletotrichum and Fusarium, and the Plant Host Defense System. United States Department of Agriculture, septiembre de 2000. http://dx.doi.org/10.32747/2000.7573069.bard.

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The intent of this proposal was to study the interaction between nonpathogenic mutants of Colletotrichum magna and Fusarium oxysporum, and the cucurbit host defense system. We had shown previously that a nonpathogenic endophytic mutant path- 1 of C. magna, caused no visible disease symptoms but protected watermelon seedlings from disease caused by the wildtype isolate and F. o. niveum. Objectives were: 1) Determine the microscopic, biochemical and molecular genetic interaction between "protected" (path- 1 colonized) cucurbit hosts and wildtype isolates of C. magna; 2) Isolate non-pathogenic mutants of F.o. melonis and test feasibility for protecting plants against fungal diseases. We found that path-1 caused no visible disease symptoms in cucurbit seedlings but conferred disease resistance against pathogenic isolates of C. magna, C. orbiculare, and F. oxysporum. Disease resistance conferred by path-1 correlated to a decrease in the time of activation of host defense systems after exposure of path-1 colonized plants to virulent pathogens. This was determined by monitoring the biochemical activity of PAL and peroxidase, and the deposition of lignin. It appears that path-1-conferred disease resistance is a multigenic phenomenon which should be more difficult for pathogen to overcome than single gene conferred resistance. Based on the benefits conferred by path-1, we have defined this mutant as expressing a mutualistic lifestyle. REMI (restriction enzyme-mediated integration) nonpathogenic mutants were also isolated using pHA1.3 plasmid linearized with Hind III and transformed into wildtype C. magna. The integrated vector and flanking genomic DNA sequences in REMI mutant R1 was re-isolated and cloned resulting in a product of approximately 11 kb designated pGMR1. Transformations of wildtype C. magna with pGMR1 resulted in the same non-pathogenic phenotype. A nonpathogenic mutant of F.o. melonis (pathogenic to melon) was isolated that colonized melon plants but elicited no disease symptoms in seedlings and conferred 25 - 50% disease protection against the virulent wildtype isolate. Subsequently, nonpathogenic mutant isolates of F.o. niveum (pathogenic to watermelon) were also isolated. Their protection capacity against the respective wildtype parent is currently under investigation. This research has provided information toward a better understanding of host-parasite interactions; specifically, endophytes, pathogens and their hosts. It will also allow us to assess the potential for utilizing nonpathogenic mutants as biological control agents against fungal pathogens and isolating molecular genetic factors of pathogenicity in Fusarium.

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Tzfira, Tzvi, Michael Elbaum y Sharon Wolf. DNA transfer by Agrobacterium: a cooperative interaction of ssDNA, virulence proteins, and plant host factors. United States Department of Agriculture, diciembre de 2005. http://dx.doi.org/10.32747/2005.7695881.bard.

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Agrobacteriumtumefaciensmediates genetic transformation of plants. The possibility of exchanging the natural genes for other DNA has led to Agrobacterium’s emergence as the primary vector for genetic modification of plants. The similarity among eukaryotic mechanisms of nuclear import also suggests use of its active elements as media for non-viral genetic therapy in animals. These considerations motivate the present study of the process that carries DNA of bacterial origin into the host nucleus. The infective pathway of Agrobacterium involves excision of a single-stranded DNA molecule (T-strand) from the bacterial tumor-inducing plasmid. This transferred DNA (T-DNA) travels to the host cell cytoplasm along with two virulence proteins, VirD2 and VirE2, through a specific bacteriumplant channel(s). Little is known about the precise structure and composition of the resulting complex within the host cell and even less is known about the mechanism of its nuclear import and integration into the host cell genome. In the present proposal we combined the expertise of the US and Israeli labs and revealed many of the biophysical and biological properties of the genetic transformation process, thus enhancing our understanding of the processes leading to nuclear import and integration of the Agrobacterium T-DNA. Specifically, we sought to: I. Elucidate the interaction of the T-strand with its chaperones. II. Analyzing the three-dimensional structure of the T-complex and its chaperones in vitro. III. Analyze kinetics of T-complex formation and T-complex nuclear import. During the past three years we accomplished our goals and made the following major discoveries: (1) Resolved the VirE2-ssDNA three-dimensional structure. (2) Characterized VirE2-ssDNA assembly and aggregation, along with regulation by VirE1. (3) Studied VirE2-ssDNA nuclear import by electron tomography. (4) Showed that T-DNA integrates via double-stranded (ds) intermediates. (5) Identified that Arabidopsis Ku80 interacts with dsT-DNA intermediates and is essential for T-DNA integration. (6) Found a role of targeted proteolysis in T-DNA uncoating. Our research provide significant physical, molecular, and structural insights into the Tcomplex structure and composition, the effect of host receptors on its nuclear import, the mechanism of T-DNA nuclear import, proteolysis and integration in host cells. Understanding the mechanical and molecular basis for T-DNA nuclear import and integration is an essential key for the development of new strategies for genetic transformation of recalcitrant plant species. Thus, the knowledge gained in this study can potentially be applied to enhance the transformation process by interfering with key steps of the transformation process (i.e. nuclear import, proteolysis and integration). Finally, in addition to the study of Agrobacterium-host interaction, our research also revealed some fundamental insights into basic cellular mechanisms of nuclear import, targeted proteolysis, protein-DNA interactions and DNA repair.

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Grumet, Rebecca y Benjamin Raccah. Identification of Potyviral Domains Controlling Systemic Infection, Host Range and Aphid Transmission. United States Department of Agriculture, julio de 2000. http://dx.doi.org/10.32747/2000.7695842.bard.

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Potyviruses form one of the largest and most economically important groups of plant viruses. Individual potyviruses and their isolates vary in symptom expression, host range, and ability to overcome host resistance genes. Understanding factors influencing these biological characteristics is of agricultural importance for epidemiology and deployment of resistance strategies. Cucurbit crops are subject to severe losses by several potyviruses including the highly aggressive and variable zucchini yellow mosaic virus (ZYMV). In this project we sought to investigate protein domains in ZYMV that influence systemic infection and host range. Particular emphasis was on coat protein (CP), because of known functions in both cell to cell and long distance movement, and helper component-protease (HC-Pro), which has been implicated to play a role in symptom development and long distance movement. These two genes are also essential for aphid mediated transmission, and domains that influence disease development may also influence transmissibility. The objectives of the approved BARD project were to test roles of specific domains in the CP and HC-Pro by making sequence alterations or switches between different isolates and viruses, and testing for infectivity, host range, and aphid transmissibility. These objectives were largely achieved as described below. Finally, we also initiated new research to identify host factors interacting with potyviral proteins and demonstrated interaction between the ZYMV RNA dependent RNA polymerase and host poly-(A)-binding protein (Wang et al., in press). The focus of the CP studies (MSU) was to investigate the role of the highly variable amino terminus (NT) in host range determination and systemic infection. Hybrid ZYMV infectious clones were produced by substituting the CP-NT of ZYMV with either the CP-NT from watermelon mosaic virus (overlapping, but broader host range) or tobacco etch virus (TEV) (non- overlapping host range) (Grumet et al., 2000; Ullah ct al., in prep). Although both hybrid viruses initially established systemic infection, indicating that even the non-cucurbit adapted TEV CP-NT could facilitate long distance transport in cucurbits, after approximately 4-6, the plants inoculated with the TEV-CPNT hybrid exhibited a distinct recovery of reduced symptoms, virus titer, and virus specific protection against secondary infection. These results suggest that the plant recognizes the presence of the TEV CP-NT, which has not been adapted to infection of cucurbits, and initiates defense responses. The CP-NT also appears to play a role in naturally occurring resistance conferred by the zym locus in the cucumber line 'Dina-1'. Patterns of virus accumulation indicated that expression of resistance is developmentally controlled and is due to a block in virus movement. Switches between the core and NT domains of ZYMV-NAA (does not cause veinal chlorosis on 'Dina-1'), and ZYMV-Ct (causes veinal chlorosis), indicated that the resistance response likely involves interaction with the CP-NT (Ullah and Grumet, submitted). At the Volcani Center the main thrust was to identify domains in the HC-Pro that affect symptom expression or aphid transmissibility. From the data reported in the first and second year report and in the attached publications (Peng et al. 1998; Kadouri et al. 1998; Raccah et al. 2000: it was shown that: 1. The mutation from PTK to PAK resulted in milder symptoms of the virus on squash, 2. Two mutations, PAK and ATK, resulted in total loss of helper activity, 3. It was established for the first time that the PTK domain is involved in binding of the HC-Pro to the potyvirus particle, and 4. Some of these experiments required greater amount of HC-Pro, therefore a simpler and more efficient purification method was developed based on Ni2+ resin.

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Shtienberg, Dan, William Fry, Amos Dinoor, Thomas Zitter y Uzi Kafkafi. Reduction in Pesticide Use in Plant Disease Control by Integration of Chemical and Non-Chemical Factors. United States Department of Agriculture, mayo de 1995. http://dx.doi.org/10.32747/1995.7613027.bard.

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The long term goal of this research project was to improve control efficiency of Alternaria diseases while reducing fungicide use, by integration of chemical and non-chemical factors. Non-chemical factors were genotype resistance, age-related resistance and fertilizers. The Specific objectives were: 1) To quantify changes in resistance among genotypes and over time in terms of disease development and specific phases of the disease cycle; 2) To quantify the effects of fertilizers applied to the foliage alone, or in combination with a fungicide, on disease development; 3) To quantify the relative contribution of genotype resistance, age-related resistance and fungicide type to the reduction of disease development; 4) To develop a strategy for integration of chemical and non-chemical factors which will achieve optimal disease suppression. The influence of physiological age of cotton plants and of the individual leaves, on disease incidence and on the rate of lesion expansion of A. macrospora was examined on leaves sampled from the field. Both parameters increased with the physiological age of individual leaves but were not affected by the age of the whole plant. The hypothesis that enrichment of the foliage with nitrogen and potassium may enhance host resistance to Alternaria and thus reduce disease severity, was examined for potato and tomato (A. solani ) and for cotton (A. macrospora ). Under controlled environment conditions, application of urea or KNO3 resulted in some reduction in disease development; however, foliar application of both nutrients (8-10 sprays in total) did not affect Alternaria severity in the field. Systemic fungicides against Alternaria (e.g. , tebuconazole and difenoconazole) are more effective than the commonly used protectant fungicides (e.g. mancozeb and chlorothalonil). Concepts for the integration of genotype resistance, age-related resistances and fungicide for the suppression of Alternaria diseases were developed and evaluated. It was found that reduction in host resistance, with age and among genotypes, can be compensated for by adjusting the intensity of fungicide applications, i.e. by increasing the frequency of sprays and by spraying systemic fungicides towards the end of the season. In, moderately resistant cultivars protection can be achieved by spraying at longer intervals than susceptible cultivars. The concepts for integration were evaluated in field trials for cotton, potatoes and tomatoes. By following these concepts it was possible to save up to five sprays out of 8-10 in a growing season.

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Chejanovsky, Nor y Bruce A. Webb. Potentiation of Pest Control by Insect Immunosuppression. United States Department of Agriculture, enero de 2010. http://dx.doi.org/10.32747/2010.7592113.bard.

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The restricted host range of many baculoviruses, highly pathogenic to Lepidoptera and non-pathogenic to mammals, limits their use to single or few closely related Lepidopteran species and is an obstacle to extending their implementation for pest control. The insect immune response is a major determinant of the ability of an insect pathogen to efficiently multiply and propagate. We have developed an original model system to study the Lepidopteran antiviral immune response based on Spodoptera littoralis resistance to AcMNPV (Autographa californica multiple nucleopolyhedrovirus) infection and the fascinating immunosuppressive activity of polydnaviruses .Our aim is to elucidate the mechanisms through which the immunosuppressive insect polydnaviruses promote replication of pathogenic baculoviruses in lepidopteran hosts that are mildly or non-permissive to virus- replication. In this study we : 1- Assessed the extent to which and the mechanisms whereby the immunosuppressive Campoletis sonorensis polydnavirus (CsV) or its genes enhanced replication of a well-characterized pathogenic baculovirus AcMNPV, in polydnavirus-immunosuppressedH. zea and S. littoralis insects and S. littoralis cells, hosts that are mildly or non-permissive to AcMNPV. 2- Identified CsV genes involved in the above immunosuppression (e.g. inhibiting cellular encapsulation and disrupting humoral immunity). We showed that: 1. S. littoralis larvae mount an immune response against a baculovirus infection. 2. Immunosuppression of an insect pest improves the ability of a viral pathogen, the baculovirus AcMNPV, to infect the pest. 3. For the first time two PDV-specific genes of the vankyrin and cystein rich-motif families involved in immunosuppression of the host, namely Pvank1 and Hv1.1 respectively, enhanced the efficacy of an insect pathogen toward a semipermissive pest. 4. Pvank1 inhibits apoptosis of Spodopteran cells elucidating one functional aspect of PDVvankyrins. 5. That Pvank-1 and Hv1.1 do not show cooperative effect in S. littoralis when co-expressed during AcMNPV infection. Our results pave the way to developing novel means for pest control, including baculoviruses, that rely upon suppressing host immune systems by strategically weakening insect defenses to improve pathogen (i.e. biocontrol agent) infection and virulence. Also, we expect that the above result will help to develop systems for enhanced insect control that may ultimately help to reduce transmission of insect vectored diseases of humans, animals and plants as well as provide mechanisms for suppression of insect populations that damage crop plants by direct feeding.

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Dawson, William O. y Moshe Bar-Joseph. Creating an Ally from an Adversary: Genetic Manipulation of Citrus Tristeza. United States Department of Agriculture, enero de 2004. http://dx.doi.org/10.32747/2004.7586540.bard.

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Citrus is one of the major agricultural crops common to Israel and the United States, important in terms of nutrition, foreign exchange, and employment. The economy of both citrus industries have been chronically plagued by diseases caused by Citrus tristeza virus (CTV). The short term solution until virus-resistant plants can be used is the use of mild strain cross-protection. We are custom designing "ideal" protecting viruses to immunize trees against severe isolates of CTV by purposely inoculating existing endangered trees and new plantings to be propagated as infected (protected) citrus budwood. We crossed the substantial technological hurdles necessary to accomplish this task which included developing an infectious cDNA clone which allows in vitro manipulation of the virus and methods to then infect citrus plants. We created a series of hybrids between decline-inducing and mild CTV strains, tested them in protoplasts, and are amplifying them to inoculate citrus trees for evaluation and mapping of disease determinants. We also extended this developed technology to begin engineering transient expression vectors based on CTV as tools for genetic improvement of tree crops, in this case citrus. Because of the long periods between genetic transformation and the ultimate assay of mature tree characteristics, there is a great need for an effective system that allows the expression or suppression of target genes in fruiting plants. Virus-based vectors will greatly expedite progress in citrus genetic improvement. We characterized several components of the virus that provides necessary information for designing virus-based vectors. We characterized the requirements of the 3 ’-nontranslated replication promoter and two 3 ’-ORF subgenomic (sg) mRNA controller elements. We discovered a novel type of 5’-terminal sgRNAs and characterized the cis-acting control element that also functions as a strong promoter of a 3 ’-sgRNA. We showed that the p23 gene controls negative-stranded RNA synthesis and expression of 3 ’ genes. We identified which genes are required for infection of plants, which are host range determinants, and which are not needed for plant infection. We continued the characterization of native dRNA populations and showed the presence of five different classes including class III dRNAs that consists of infectious and self-replicating molecules and class V dRNAs that contain all of the 3 ’ ORFs, along with class IV dRNAs that retain non-contiguous internal sequences. We have constructed and tested in protoplasts a series of expression vectors that will be described in this proposal.

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