Academic literature on the topic 'Parasitic plants Host plants'

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Journal articles on the topic "Parasitic plants Host plants"

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Amuchástegui, Andrea, Letizia Petryna, Juan José Cantero, and César Núñez. "Plantas parásitas del centro de Argentina." Acta Botanica Malacitana 28 (January 1, 2003): 37–46. http://dx.doi.org/10.24310/abm.v28i0.7264.

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RESUMEN. Plantas parásitas del centro de Argentina. Este trabajo consiste en la identificación de las especies de plantas parásitas del centro de la Argentina. Se incluye una clave diferencial para las mismas e ilustraciones. Se han identificado 8 especies parásitas distribuidas en 5 familias y 8 géneros, las que representan aproximadamente el 0.6 % de la flora vascular de esta región. Cuatro especies parasitan a plantas leñosas y las restantes parasitan hierbas. La mayor cantidad de especies huéspedes se encuentran en la familia Leguminosac.Palabras Clave. Plantas parásitas, Flora, Argentina.SUMMARY. Parasitic flowering plants of central Argentina. In this contribution a synopsis of the whole species of Parasitic flowering plants from central Argentina, is presented. In this area 8 taxa belonging to 5 families and 8 genera, that represent 0.6 % of the regional flora, have been found. A key based in vegetative and reproductive characters, and illustrations of all species are included. Trees are host of four species, others have been found associated with herbs. Leguminosae is the main host family.Key words. Parasitic plants, Flora, Argentina.
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Tambunan, Meidoraeka Rigine, and Reza Raihandhany. "Jenis-Jenis Tumbuhan Parasit dan Persebarannya di Institut Teknologi Bandung (ITB) Kampus Ganesha." Jurnal Sumberdaya Hayati 6, no. 2 (December 31, 2020): 47–55. http://dx.doi.org/10.29244/jsdh.6.2.47-55.

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Parasitic plants are a group of plants that live and have a broad ecological distribution which in general attack trees, shrubs or herbs to be used as a host. Some parasitic plants attacked some plants in Institut Teknologi Bandung (ITB) Ganesha Campus, Bandung. Exploration and collection of these parasitic plants in this area are conducted. Three parasitic plants species, such as Cuscuta australis, Scurrula parasitica, and Dendrophthoe pentandra are recorded and they attack 7 other plants species in ITB Ganesha. S. parasitica is reported as the highest population species to parasiting 5 plants species, while C. australis only parasiting 3 plants species and D. pendantra is parasiting 4 plants.
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Hu, Luyang, Jiansu Wang, Chong Yang, Faisal Islam, Harro Bouwmeester, Stéphane Muños, and Weijun Zhou. "The Effect of Virulence and Resistance Mechanisms on the Interactions between Parasitic Plants and Their Hosts." International Journal of Molecular Sciences 21, no. 23 (November 27, 2020): 9013. http://dx.doi.org/10.3390/ijms21239013.

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Parasitic plants have a unique heterotrophic lifestyle based on the extraction of water and nutrients from host plants. Some parasitic plant species, particularly those of the family Orobanchaceae, attack crops and cause substantial yield losses. The breeding of resistant crop varieties is an inexpensive way to control parasitic weeds, but often does not provide a long-lasting solution because the parasites rapidly evolve to overcome resistance. Understanding mechanisms underlying naturally occurring parasitic plant resistance is of great interest and could help to develop methods to control parasitic plants. In this review, we describe the virulence mechanisms of parasitic plants and resistance mechanisms in their hosts, focusing on obligate root parasites of the genera Orobanche and Striga. We noticed that the resistance (R) genes in the host genome often encode proteins with nucleotide-binding and leucine-rich repeat domains (NLR proteins), hence we proposed a mechanism by which host plants use NLR proteins to activate downstream resistance gene expression. We speculated how parasitic plants and their hosts co-evolved and discussed what drives the evolution of virulence effectors in parasitic plants by considering concepts from similar studies of plant–microbe interaction. Most previous studies have focused on the host rather than the parasite, so we also provided an updated summary of genomic resources for parasitic plants and parasitic genes for further research to test our hypotheses. Finally, we discussed new approaches such as CRISPR/Cas9-mediated genome editing and RNAi silencing that can provide deeper insight into the intriguing life cycle of parasitic plants and could potentially contribute to the development of novel strategies for controlling parasitic weeds, thereby enhancing crop productivity and food security globally.
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Mescher, Mark C., Justin Runyon, and Consuelo M. De Moraes. "Plant Host Finding by Parasitic Plants." Plant Signaling & Behavior 1, no. 6 (November 2006): 284–86. http://dx.doi.org/10.4161/psb.1.6.3562.

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Nelson, David C. "The mechanism of host-induced germination in root parasitic plants." Plant Physiology 185, no. 4 (February 3, 2021): 1353–73. http://dx.doi.org/10.1093/plphys/kiab043.

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Abstract Chemical signals known as strigolactones (SLs) were discovered more than 50 years ago as host-derived germination stimulants of parasitic plants in the Orobanchaceae. Strigolactone-responsive germination is an essential adaptation of obligate parasites in this family, which depend upon a host for survival. Several species of obligate parasites, including witchweeds (Striga, Alectra spp.) and broomrapes (Orobanche, Phelipanche spp.), are highly destructive agricultural weeds that pose a significant threat to global food security. Understanding how parasites sense SLs and other host-derived stimulants will catalyze the development of innovative chemical and biological control methods. This review synthesizes the recent discoveries of strigolactone receptors in parasitic Orobanchaceae, their signaling mechanism, and key steps in their evolution.
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Zagorchev, Lyuben, Wolfgang Stöggl, Denitsa Teofanova, Junmin Li, and Ilse Kranner. "Plant Parasites under Pressure: Effects of Abiotic Stress on the Interactions between Parasitic Plants and Their Hosts." International Journal of Molecular Sciences 22, no. 14 (July 10, 2021): 7418. http://dx.doi.org/10.3390/ijms22147418.

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Parasitic angiosperms, comprising a diverse group of flowering plants, are partially or fully dependent on their hosts to acquire water, mineral nutrients and organic compounds. Some have detrimental effects on agriculturally important crop plants. They are also intriguing model systems to study adaptive mechanisms required for the transition from an autotrophic to a heterotrophic metabolism. No less than any other plant, parasitic plants are affected by abiotic stress factors such as drought and changes in temperature, saline soils or contamination with metals or herbicides. These effects may be attributed to the direct influence of the stress, but also to diminished host availability and suitability. Although several studies on abiotic stress response of parasitic plants are available, still little is known about how abiotic factors affect host preferences, defense mechanisms of both hosts and parasites and the effects of combinations of abiotic and biotic stress experienced by the host plants. The latter effects are of specific interest as parasitic plants pose additional pressure on contemporary agriculture in times of climate change. This review summarizes the existing literature on abiotic stress response of parasitic plants, highlighting knowledge gaps and discussing perspectives for future research and potential agricultural applications.
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Mower, Jeffrey P., Saša Stefanović, Gregory J. Young, and Jeffrey D. Palmer. "Gene transfer from parasitic to host plants." Nature 432, no. 7014 (November 2004): 165–66. http://dx.doi.org/10.1038/432165b.

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Clarke, Christopher R., Michael P. Timko, John I. Yoder, Michael J. Axtell, and James H. Westwood. "Molecular Dialog Between Parasitic Plants and Their Hosts." Annual Review of Phytopathology 57, no. 1 (August 25, 2019): 279–99. http://dx.doi.org/10.1146/annurev-phyto-082718-100043.

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Parasitic plants steal sugars, water, and other nutrients from host plants through a haustorial connection. Several species of parasitic plants such as witchweeds ( Striga spp.) and broomrapes ( Orobanche and Phelipanche spp.) are major biotic constraints to agricultural production. Parasitic plants are understudied compared with other major classes of plant pathogens, but the recent availability of genomic and transcriptomic data has accelerated the rate of discovery of the molecular mechanisms underpinning plant parasitism. Here, we review the current body of knowledge of how parasitic plants sense host plants, germinate, form parasitic haustorial connections, and suppress host plant immune responses. Additionally, we assess whether parasitic plants fit within the current paradigms used to understand the molecular mechanisms of microbial plant–pathogen interactions. Finally, we discuss challenges facing parasitic plant research and propose the most urgent questions that need to be answered to advance our understanding of plant parasitism.
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Yuan, Yongge, and Junmin Li. "Effects of Parasitism on the Competitive Ability of Invasive and Native Species." Life 12, no. 11 (November 6, 2022): 1800. http://dx.doi.org/10.3390/life12111800.

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Parasitic plants can often seriously harm host plants and, thus, alter competitive dominance between hosts and neighbouring species. However, whether and how parasitic plants differently affect the competitive abilities of invasive and the native plants have not been tested. In this study, we used Cuscuta grovonii as the parasitic plants and three invasive plants and three native plants as host plants. Host plants grown alone or in competition with Coix lacryma-jobi were either parasitized with Cuscuta grovonii or not parasitized. Parasitism caused similar damage to invasive and native plants when grown with Cuscuta grovonii alone but caused less damage to invasive species than native species when grown in competition. Parasitism increased the competitive ability of invasive plants but did not affect the competitive ability of native plants. In the absence of parasitism, the competitive ability of host plants was significantly negatively correlated with the competitive ability of Coix lacryma-jobi, but under parasitism, there was no significant relationship of the competitive ability between host and competitor plants. Our results indicated that parasitic plants can increase the competitive tolerance of invasive plants, but have no effect on native plants. Thus, parasitism may play an important role in the process of plant invasion.
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Okubamichael, Desale Y., Megan E. Griffiths, and David Ward. "Host specificity in parasitic plants—perspectives from mistletoes." AoB Plants 8 (2016): plw069. http://dx.doi.org/10.1093/aobpla/plw069.

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Dissertations / Theses on the topic "Parasitic plants Host plants"

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Soriano, Imelda Rizalina. "Novel inducible phytochemical defences against plant parasitic nematodes /." Title page, table of contents and summary only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phs7141.pdf.

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Flagg, Jeannine K. "Cross-Species Translocation of mRNA from Host Plants into the Parasitic Plant Dodder." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/31909.

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Dodders (Cuscuta spp.) are parasitic plants that live by tapping into the vascular tissue of a host plant. Contents of the host phloem translocate readily into the parasite, and shared plasmodesmata have been documented between host cortical cells and dodder searching hyphae. Dodder is known to transmit viruses from one host to another, which is consistent with viral ability to traverse plasmodesmata (PD) with the aid of movement proteins (MPs). Plant endogenous mRNAs may also associate with specific proteins to pass through PD and traffic long distances in the phloem, a process that appears to play a role in coordination of development. We have evaluated the hypothesis that dodder is able to accumulate host phloem-mobile mRNAs by assaying lespedeza dodder (C. pentagona) for the presence of host transcripts. Reverse transcriptase PCR (RT-PCR) and tomato microarrays were used to probe RNA from dodder parasitizing tomato. Transcripts from four tomato genes were detected in dodder grown on tomato, but were not detected in control dodder grown on other hosts. Notable among these was LeGAI, a transcript previously shown to be phloem translocated. In addition, RT-PCR of RNA from dodder grown on pumpkin detected three mobile pumpkin mRNAs (CmNACP, CmSUTP1, and CmWRKYP). These results imply the existence of an extraordinary situation in which mobile mRNAs move from one plant into another, and raise questions about the role of this phenomenon in plant development and parasite pathogenicity.
Master of Science
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Mahdy, Magdy. "Biological control of plant parasitic nematodes with antagonistic bacteria on different host plants." Bonn : Rheinische Friedrick-Wilhelms-Universität, Institut für Pflanzenkrankheiten, 2002. http://hss.ulb.uni-bonn.de/ulb_bonn/diss_online/landw_fak/2002/mahdy_magdy/0203.pdf.

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Kelly, Colleen Kay. "Host use and foraging in the parasitic plant Cuscuta subinclusa." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184543.

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Foraging theory predicts active responses by organisms upon encounter with a resource, as opposed to the passive responses of differential survivorship and growth. Stems of the parasitic plant Cuscuta subinclusa invest in resource acquisition (coil) relative to host quality in a way predicted by the marginal value theorem (MVT) in that: (1) stem coiling, the necessary antecedent and determinant of resource uptake, precedes exploitation of host materials; and (2) mean coiling on a host species is proportional to: (a) mean growth/haustorium, (b) mean biomass accumulation over the season, and (c) mean parasite growth/host individual. Coiling is correlated with growth/host individual for the 5 native host species examined, but not when a non-native species is added to the model, suggesting coiling response is a result of natural selection. Preliminary evidence indicates that coiling in C. subinclusa is induced by host bark chemicals. Resource-poor stems of C. subinclusa are more likely to coil, and coil more, than resource-rich stems, thus nutritional state of the parasite as well as host value affects foraging responses. Evidence from other experiments suggests that the costs of growth, or "search costs", may affect host acceptability. When water is readily available, transplanted C. subinclusa stems are less likely to coil on branches of Platanus racemosa. During the dry season, when cellular expansion is difficult, all p. racemosa branches were coiled upon. Large parasites are more likely to over-winter and set seed a second season, and parasites that start from over-wintered tissue are significantly larger at flowering than are those that have started from seed. Seed set is correlated with parasite size, thus linking foraging response and fitness of the plant. C. subinclusa's foraging response does not, however, predict population level patterns of host use. The principal determinant of host use by C. subinclusa is average proximity of a species to Malosma laurina. Parasite individuals infest many host species each season, but initially establish, set most seed, and over-winter only on M. laurina. Individual response of C. subinclusa contributes to the model of host use only after proximity to M. laurina is accounted for, suggesting that mechanisms maximizing exploitation of a host take effect after contact between host and parasite.
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Houngbédji, Tossimidé. "Rhamphicarpa fistulosa : infestation dans les bas-fonds rizicoles de la Région des Savanes (Togo) et étude des interactions hôte-parasite." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS455/document.

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Une des contraintes biotiques majeures de la riziculture de bas-fond au nord du Togo est l’adventice parasite Rhamphicarpa fistulosa (Hochst.) Benth. Afin d’évaluer les options stratégiques pour contrôler efficacement R. fistulosa, notre étude a été conduite avec comme principaux objectifs : 1) l’identification de la répartition de R. fistulosa et l’étude des facteurs qui favorisent son infestation, 2) l’étude de l’impact des niveaux d’infestation sur la flore adventice du riz, et 3) la caractérisation des interactions hôte-parasite et de leurs impacts sur le développement de l’hôte et les performances reproductives du parasite. A l’issu des prospections de terrain, les plus fortes infestations ont été retrouvées sur des sols majoritairement à texture sableuse et très pauvres en matière organique. Une flore adventice très diversifiée a été retrouvée en présence de R. fistulosa, certaines adventices pouvant être parasitées et constituer éventuellement un réservoir pour accroître le stock semencier du parasite. En conditions contrôlées, R. fistulosa se développe et se reproduit aussi bien sur le riz que sur la tomate, alors que le soja retarde la reproduction du parasite. La germination des graines de R. fistulosa est maximale en présence de graines de plantes cultivées ou adventices. Les graines nouvellement récoltées ont une dormance de plus de six mois, mais leur germination a été stimulée par la présence de phytohormones. En conclusion, les meilleures stratégies de lutte doivent impliquer le contrôle par les semis tardifs, les rotations culturales avec les légumineuses comme le soja, l’arachide ou le niébé, et les cultures maraîchères
Main biotic constraints to rain-fed lowland rice cultivation in northern Togo include the parasitic weed Rhamphicarpa fistulosa (Hochst.) Benth. In order to evaluate efficient strategies to control R. fistulosa, our study was performed taking into account the following main objectives: 1) Identification of the distribution of R. fistulosa and study of the factors favouring its infestation, 2) Study of the impacts of infestation levels on rice weed communities, and 3) Characterization of the host-parasite interactions and their impacts on the host development and the parasite reproduction. Following fields investigations, highest infestations were observed on sandy soils with low levels of organic matter.In addition, weed flora found in the presence of R. fistulosa was much diversified and some weeds were found to been parasitized and could possibly constitute reservoirs to increase the seed stock of the parasite. In controlled experiments, R. fistulosa grown and reproduced better on rice and tomato crops, than on soybean which delayed the reproduction of the parasite. Germination of R. fistulosa seeds was stimulated in presence of cultivated crops or weeds. New collected seeds shown six months dormancy but their germination was stimulated in presence of phytohormones. In conclusion, the best strategies to control R. fistulosa must include delayed sowing, crop rotation with leguminous species (i.e. soybean, peanut or cowpea) and vegetable cropsKeywords: Rhamphicarpa fistulosa, rice, lowland, parasitism, host-parasite interaction, weeds
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Suetsugu, Kenji. "Diverse interactions of heterotrophic plants with their hosts, pollinators and seed dispersers." Kyoto University, 2014. http://hdl.handle.net/2433/192205.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第18605号
人博第701号
新制||人||167(附属図書館)
26||人博||701(吉田南総合図書館)
31505
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授 加藤 眞, 教授 市岡 孝朗, 教授 瀬戸口 浩彰, 教授 宮本 嘉久, 教授 新宮 一成
学位規則第4条第1項該当
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Cameron, Duncan Drummond. "A role for differential host resistance to the hemiparasitic angiosperm, Rhinanthus minor L. in determining the structure of host plant communities?" Thesis, University of Aberdeen, 2004. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238495.

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This study describes the effect of the root hemi-parasitic angiosperm Rhinanthus minor on the structure of the communities in which it lives and seeks to elucidate a mechanism through which the parasite acts to effect these changes in the community. Field manipulations reveal that R. minor suppressed the growth of grasses and legumes in a newly sown meadow whilst promoting the forbs within one growing season. In contrast the removal of R. minor from mature meadow plots did not influence their composition. After an additional growing season the parasite did not further influence the composition of the new meadows but removal did begin to benefit the biomass of mature plots. In isolation the parasite caused most damage to grasses whilst leaving legumes and forbs undamaged. Moreover, the parasite performed worst in terms of growth and photosynthesis when attached to the forbs. Consequently the parasite was able to moderate intra-specific competition between grasses and forbs. I thus hypothesised that forbs were able to prevent the parasite form abstracting resources where as grasses could not. Tracer experiments using isotopically e5N) labelled potassium nitrate confirmed this hypothesis showing that more of the resources taken up by the host were stolen by the parasite from grasses than from forbs. There was much variability in the translocation of resources from the legume studied. The reasons underlying the differential uptake of resources were highlighted using histological studies which showed that all of the forbs possessed successful resistance mechanisms to the parasite whilst no successful resistance was observed in the grasses or legumes. Two different resistance mechanisms were observed in the forbs; hypersensitive cell-death at the host-parasite interface and host lignification. I therefore propose that differential host resistance may underlie this parasite's community level effects as forbs possess a resistance capacity that other potential hosts do not.
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Junior, Mauro Ferreira Bonfim. "Avaliação da capacidade reprodutiva de populações de Pratylenchus spp. frente a diferentes espécies vegetais." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/11/11135/tde-25022010-081502/.

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Os nematoides que atualmente tem sido classificados como P. coffeae, demonstram ampla variabilidade morfológica, molecular e quanto à reação à diferentes hospedeiros. Por conseguinte, é essencial que se identifique corretamente as espécies e que se conheça a capacidade de parasitismo em alguns hospedeiros, para que se possa estabelecer medidas de controle e estimar eventuais riscos da entrada de um patógeno em uma área com hospedeiro suscetível. Neste sentido, a presente pesquisa propõe, numa primeira parte, uma medida de controle de P. jaehni (K5), que é muito agressivo à cafeeiro arábico, baseada no uso de plantas má hospedeiras. Na segunda parte deste trabalho é realizada uma caracterização da reação de diferentes espécies vegetais à quatro populações de Pratylenchus spp. Em virtude do exposto, este estudo objetivou avaliar a reação de diferentes cultivares de feijoeiro comum frente à P. jaehni (K5), visando seu possível uso no manejo de áreas cafeeiras infestadas e caracterizar a reação de diferentes espécies vegetais de importância econômica (café, porta-enxertos cítricos, banana e sorgo) frente à quatro populações de Pratylenchus spp. As populações inciais utilizadas nos experimentos variaram entre 180 e 200 nematóides. Em todos os experimentos, os nematóides foram extraídos das raízes pelo método de Coolen e D´Herde (1972) e, eventualmente, do substrato pelo método de Jenkins (1964). Foram realizados três ensaios: i) o primeiro com feijoeiro comum, onde todas as cultivares utilizadas foram resistentes à P. jaehni (K5), inclusive na réplica; ii) o segundo com porta-enxertos cítricos, no qual somente o limão-cravo foi hospedeiro de P. jaehni (K5); iii) o terceiro, no qual foi utilizado café, limão-cravo, banana e sorgo para o conhecimento das respectivas reações frente à 4 populações de Pratylenchus spp. Neste último experimento ocorreu uma reação hospedeira diferenciada para cada população. De acordo com os resultados, concluise que as cultivares de feijoeiro comum utilizadas apresentam potencial de uso em áreas cafeeiras infestadas por P. jaehni (K5), em consórcio ou em áreas de renovação de cafezal, e que as populações de Pratylenchus spp. são capazes de se reproduzir de forma diferenciada frente às espécies vegetais testadas.
Nematode populations that have been classified as P. coffeae show wide morphological, molecular and host range variability. Therefore, is essential the correct identification of the species and the knowledge about its parasitism capacity on some hosts, to ensure appropriate control measures and to estimate the entry risks of a pathogen in an area with susceptible host. In this sense, the present research report, firstly, propose a control measure of P. jaehni (K5), which is very aggressive to the arabic coffee, based on the use of poor host plants. In the second part, was carried out a host status evaluation of different plant species to four populations of Pratylenchus spp. In this context, were evaluated the reaction of different common bean cultivars to P. jaehni (K5), for its possible use in management of coffee areas infested with this nematode, and characterized the response of different economic important plant species (coffee, citrus rootstocks, banana and sorghum) to four populations of Pratylenchus spp (IB01P, IB02P, K5 e C1). The initial population used in experiments ranged between 180 and 200 nematodes. In all experiments, nematodes were extracted from roots by Coolen e D\'Herde´s method (1972) and eventually from the substrate by Jenkins´ method (1964). Three assays were conducted and results was as following: i) in the first one, with common bean, all tested cultivars were resistant to P. jaehni (K5), including the replica; ii) in the second one, with rootstocks, only rangpur lime was a good host of P. jaehni (K5); iii) in the third one, in which was used coffee, rangpur lime, banana and grain sorghum, was observed a differential host reaction for each nematode population evaluated. According to the present results, we suggest that common bean cultivars tested have great potential for use, or in intercropping or in crop rotation, in coffee areas infested by P. jaehni (K5) and populations of Pratylenchus spp. have different reproductive fitness in the plants species tested.
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Reverter, Miriam. "Host-parasite interactions of coral reef fish." Thesis, Paris, EPHE, 2016. http://www.theses.fr/2016EPHE3060/document.

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Les parasites sont une partie très importante des écosystèmes, néanmoins, dans certains cas tels que l’aquaculture ils causent des épidémies. Dans cette thèse j’ai étudié les interactions hôte-parasite chez les poissons coralliens, dans les milieux naturels et les milieux aquacoles. J’ai étudié l’arrangement des communautés de 13 espèces de monogènes de 34 espèces de poissons papillon dans l’Indo-Pacifique. Les résultats montrent qu’il existe un patron de distribution stable des espèces, ce qui, combiné avec les résultats de l’étude biogéographique, suggère que la spécificité parasitaire observée a pu se développer tout au long des épisodes biogéographiques passés. Notamment, seule une espèce, Chaetodon lunulatus, n’est jamais parasitée. J’ai étudié le mucus des poissons qui est décrit comme la première ligne de défense contre des agressions externes, pour analyser quels facteurs de C. lunulatus pourraient être reliés à l’absence des parasites. Le microbiome et le métabolome du mucus branchial des poissons papillons montrent une grande diversité. C. lunulatus présente une plus grande abondance de Fusobactéries qui est corrélée avec une surexpression de peptides pouvant dériver de la β-hémoglobine. La purification, la synthèse et l’évaluation des activités antiparasitaires des peptides sont en cours au laboratoire. J’ai aussi étudié l’utilisation des plantes médicinales comme alternative à des traitements chimiques dans l’aquaculture. J’ai testé l’activité antibactérienne et immunostimulatrice de plusieurs plantes et algues polynésiennes. L’algue rouge Asparagopsis taxiformis montre de fortes activités antibactériennes sur Vibrio harveyi et Tenacibaculum maritimum et induit une augmentation de l’expression de deux gènes liés à l’immunité chez Platax orbicularis
Fish parasites are an important part of ecosystems, however, in certain cases such as in aquaculture they can cause severe disease outbreaks. In this thesis I have studied host-parasite interactions in coral reef fishes, both in the natural and culture environments. I have studied the distribution of 13 dactylogyrid species from 34 butterflyfishes in the Indo West-Pacific. Composition of dactylogyrid communities was host specific and together with the biogeography results, where a turnover in the main Haliotrema species was observed, suggest that parasite specificity might result from host-parasite coevolution derived from past biogeographical episodes. Only one butterflyfish species, Chaetodon lunulatus, was never found parasitized by gill monogeneans. I have studied the butterflyfish mucus, which is the first barrier against pathogens, to investigate the C. lunulatus factors that might be related to the monogenean absence. Butterflyfish gill microbiome and metabolome revealed a high diversity. C. lunulatus presented a significantly higher abundance of Fusobacteria which was correlated to a higher expression of potentially derived β-hemoglobin peptides. Synthesis and evaluation of the peptide antiparasitic activities are being performed in the laboratory. I have also studied the use of medicinal plants as an alternative to chemotherapy in fish aquaculture. I investigated the antibacterial and immunostimulant activities of several local Polynesian plants and algae, and I found that Asparagopsis taxiformis displayed a potent antibacterial activity against Vibrio harveyi and Tenacibaculum maritmum and increased expression of two immune-related genes in Platax orbicularis
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Mandyam, Keerthi. "Dark septate fungal endophytes from a tallgrass prairie and their continuum of interactions with host plants." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1127.

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Books on the topic "Parasitic plants Host plants"

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Maqbool, M. A. Distribution & host association of plant parasitic nematodes in Pakistan. Karachi, Pakistan: National Nematological Research Centre, University of Karachi, 1992.

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Classification and distribution of plant parasitic nematodes in Pakistan. Karachi, Pakistan: National Nematological Research Centre, University of Karachi, 1986.

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Grandison, Gordon S. Plant-parasitic nematodes of American Samoa. Noumea, New Caledonia: South Pacific Commission, 1996.

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Bhandari, N. N. The haustorium. Taunton, Somerset, England: Research Studies Press, 1993.

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Miyazaki, Masahisa. Nihon-san azamiuma bunken, kishu shokubutsu mokuroku. Ibaraki-ken Tsukuba-shi: Nōrin Suisanshō Nōgyō Kankyō Gijutsu Kenkyūjo, 1988.

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Belmont, Roberto Montes. Las enfermedades de las plantas en Oaxaca. [Oaxaca, Mexico]: Instituto Politécnico Nacional, Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional, Unidad Oaxaca, 1988.

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Deverall, Brian J. Defence mechanisms of plants. Cambridge: Cambridge University Press, 2009.

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Scharpf, Robert F. Management of western dwarf mistletoe in ponderosa and Jeffrey pines in forest recreation areas. Berkeley, Calif: U.S. Dept. of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station, 1988.

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Scharpf, Robert F. Management of western dwarf mistletoe in ponderosa and Jeffrey pines in forest recreation areas. Berkeley, Calif: U.S. Dept. of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station, 1988.

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Scharpf, Robert F. Management of western dwarf mistletoe in ponderosa and Jeffrey pines in forest recreation areas. [Berkeley, Calif.]: U.S. Dept. of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station, 1988.

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Book chapters on the topic "Parasitic plants Host plants"

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Timko, Michael P., and Julie D. Scholes. "Host Reaction to Attack by Root Parasitic Plants." In Parasitic Orobanchaceae, 115–41. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-38146-1_7.

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Liao, Zhen, Kristian Persson Hodén, and Christina Dixelius. "Small talk and large impact: the importance of small RNA molecules in the fight against plant diseases." In RNAi for plant improvement and protection, 86–93. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789248890.0009.

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Abstract This short and general chapter summarizes how plants and pathogens communicate using not only proteins for recognition and signal transduction or other metabolites but also RNA molecules where small RNAs with sizes between 21 to 40 nt are most important. These small RNAs can move between plants and a range of interacting pathogenic organisms in both directions, that is, a 'cross-kingdom' communication process. The first reports on RNA-based communications between plants and plant pathogenic fungi appeared about 10 years ago. Since that time, we have learnt much about sRNA biology in plants and their function in different parasitic organisms. However, many questions on the processes involved remain unanswered. Such information is crucial in order to sustain high crop production. Besides giving a brief background, we highlight the interactions between the potato late blight pathogen and its plant host potato.
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Liao, Zhen, Kristian Persson Hodén, and Christina Dixelius. "Small talk and large impact: the importance of small RNA molecules in the fight against plant diseases." In RNAi for plant improvement and protection, 86–93. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789248890.0086.

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Abstract This short and general chapter summarizes how plants and pathogens communicate using not only proteins for recognition and signal transduction or other metabolites but also RNA molecules where small RNAs with sizes between 21 to 40 nt are most important. These small RNAs can move between plants and a range of interacting pathogenic organisms in both directions, that is, a 'cross-kingdom' communication process. The first reports on RNA-based communications between plants and plant pathogenic fungi appeared about 10 years ago. Since that time, we have learnt much about sRNA biology in plants and their function in different parasitic organisms. However, many questions on the processes involved remain unanswered. Such information is crucial in order to sustain high crop production. Besides giving a brief background, we highlight the interactions between the potato late blight pathogen and its plant host potato.
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Haque, Ziaul, and Mujeebur Rahman Khan. "Pratylenchidae: Achlysiella, Hirschmanniella, Nacobbus, Pratylenchus, Radopholus and Zygotylenchus species." In Handbook of invasive plant-parasitic nematodes, 337–406. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247367.0011.

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Abstract This chapter provides information on geographical distribution; host plants; symptoms; biology and life cycle; economic importance; movement and means of dispersal; pest risk analysis; invasiveness rating; management measures, including cultural, host resistance, biological, and chemical control; and detailed account of diagnosis procedures, such as morphological, biochemical, and molecular characterization, of Achlysiella, Hirschmanniella, Nacobbus, Pratylenchus, Radopholus and Zygotylenchus species.
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Haque, Ziaul, and Mujeebur Rahman Khan. "Aphelenchidae: Aphelenchoides and Bursaphelenchus species." In Handbook of invasive plant-parasitic nematodes, 58–99. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247367.0003.

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Abstract This chapter provides information on: geographical distribution; host plants; symptoms; biology and life cycle; economic importance; movement and means of dispersal; pest risk analysis; invasiveness rating; management measures; and detailed account of diagnosis procedures, such as morphological, biochemical, and molecular characterization, of Aphelenchoides and Bursaphelenchus species.
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Haque, Ziaul, and Mujeebur Rahman Khan. "Anguinidae: Anguina and Ditylenchus species." In Handbook of invasive plant-parasitic nematodes, 18–57. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247367.0002.

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Abstract The gall-forming nematodes, Anguina spp., are obligate parasites and attack aerial plants parts of cereals and forage grasses. The genus Ditylenchus contains a large number of species which are mostly myceliophagous. A few species are phytophagous, but are of great importance as they attack more than 1200 species of cultivated and wild plants. This chapter includes information on: geographical distribution; host ranges; symptoms; biology and life cycle; economic importance; movement and means of dispersal; pest risk analysis; invasiveness; management measures; and detailed account of diagnosis procedures, such as morphological, biochemical, cytogenetic and molecular characterization, of Anguina and Ditylenchus species.
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Haque, Ziaul, and Mujeebur Rahman Khan. "Trichodoridae: Nanidorus, Paratrichodorus and Trichodorus species." In Handbook of invasive plant-parasitic nematodes, 426–38. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247367.0014.

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Abstract This chapter provides information on geographical distribution; host plants; vectors; symptoms; biology and life cycle; economic importance; movement and means of dispersal; pest risk analysis; invasiveness rating; management measures; and detailed account of diagnosis procedures, such as morphological and molecular characterization, of Nanidorus, Paratrichodorus and Trichodorus species.
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Haque, Ziaul, and Mujeebur Rahman Khan. "Heterodoridae: Cactodera, Globodera, Heterodera and Punctodera species." In Handbook of invasive plant-parasitic nematodes, 121–96. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247367.0007.

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Abstract This chapter provides information on geographical distribution; host plants; symptoms; biology and life cycle; economic importance; movement and means of dispersal; pest risk analysis; invasiveness rating; management measures; and detailed account of diagnosis procedures, such as morphological, biochemical, and molecular characterization, of Cactodera, Globodera, Heterodera and Punctodera species.
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Haque, Ziaul, and Mujeebur Rahman Khan. "Hoplolaimidae: Aphasmatylenchus, Helicotylenchus, Hoplolaimus and Scutellonema species." In Handbook of invasive plant-parasitic nematodes, 197–240. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247367.0008.

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Abstract This chapter provides information on geographical distribution; host plants; symptoms; biology and life cycle; economic importance; movement and means of dispersal; pest risk analysis; invasiveness rating; management measures; and detailed account of diagnosis procedures, such as morphological, biochemical, and molecular characterization, of Aphasmatylenchus, Helicotylenchus, Hoplolaimus and Scutellonema species.
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Haque, Ziaul, and Mujeebur Rahman Khan. "Tylenchulidae: Tylenchulus species." In Handbook of invasive plant-parasitic nematodes, 439–45. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247367.0015.

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Abstract This chapter provides information on geographical distribution; host plants; symptoms; biology and life cycle; economic importance; movement and means of dispersal; pest risk analysis; invasiveness rating; management measures, including cultural, pest resistance, biological, and chemical control; and detailed account of diagnosis procedures, such as morphological and molecular characterization, of Tylenchulus species.
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Conference papers on the topic "Parasitic plants Host plants"

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Gorshkov, V. Yu, O. E. Petrova, O. I. Parfirova, B. R. Islamov, N. E. Gogolev, R. F. Gubaev, A. G. Daminova, et al. ""Equilibrium" in the parasite-host system: physiological foundations, molecular players." In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-13.

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Solikin. "Parasitic Plants and Their Hosts in Pucak Botanic Garden Maros South Sulawesi Province." In International Conference Recent Innovation. SCITEPRESS - Science and Technology Publications, 2018. http://dx.doi.org/10.5220/0009915107140719.

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Buck, R., M. Eck, and M. Wittmann. "Dual Receiver Concept for Solar Towers up to 100MW." In ASME 2005 International Solar Energy Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/isec2005-76114.

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The Dual Receiver Concept presented in this paper improves the adaptation of the central receiver to the steam cycle in a solar thermal power plant. By combination of an open volumetric air heater and a tubular evaporator the Dual-Receiver Concept profits from the advantages of these two concepts while their characteristic problems are avoided. The water is evaporated directly in the tubular steam generator, preheating and superheating is done in heat exchangers by using the hot air from the volumetric receiver (Fig. 1). This paper presents a concept study that extends previous work on the 10 MWel level (Buck et al. 2004) to a level of 100 MWel which is the expected power range of future plants. The results confirm the benefits of the new concept, resulting from higher thermal efficiency of the receiver and lower parasitic power consumption. The annual mean efficiency is increased from 13% to 16%. Advantageous are also the reduced thermal loads in the receiver components.
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Ibrahim, N. J., B. M. Md-Zain, and S. Yaakop. "Relationships between parasitoid wasps (Hymenoptera: Braconidae: Opiinae), fruit flies (Diptera: Tephritidae) and their host plants based on 16S rRNA, 12S rRNA, and ND1 gene sequences." In THE 2013 UKM FST POSTGRADUATE COLLOQUIUM: Proceedings of the Universiti Kebangsaan Malaysia, Faculty of Science and Technology 2013 Postgraduate Colloquium. AIP Publishing LLC, 2013. http://dx.doi.org/10.1063/1.4858679.

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Брадовская, Наталья, Виктор Брадовский, and Мария Мардарь. "Перспективы разведения и применения Triaspis thoracicus Cur. В контроли численности гороховой зерновки (Bruchus pisorum L.)." In International Scientific Symposium "Plant Protection – Achievements and Prospects". Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2020. http://dx.doi.org/10.53040/9789975347204.28.

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In this article, the problems of the possibility to use the bean weevil as alternative host for laboratory rearing of Triaspis-effective parasite of pea weevil, the most dangerous pest of pea, are elucidated, as well as the data of studying of some bioecologic peculiarities of this parasite.
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Yosano, Shun. "The discrimination between host plants and nonhost plants by tarsi in Chrysomelidae." In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.111850.

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Bianchini, Franco, Gianfranco Fenu, Giulia Giordano, and Felice Andrea Pellegrino. "Model-free tuning of plants with parasitic dynamics." In 2017 IEEE 56th Annual Conference on Decision and Control (CDC). IEEE, 2017. http://dx.doi.org/10.1109/cdc.2017.8263713.

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Li, Xianchun. "How do insect herbivores "spy" on their host plants?" In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.94050.

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Santander, R. D., E. Marco-Noales, M. Ordax, and E. G. Biosca. "Erwinia amylovora colonization of host plants inoculated by irrigation." In Proceedings of the III International Conference on Environmental, Industrial and Applied Microbiology (BioMicroWorld2009). WORLD SCIENTIFIC, 2010. http://dx.doi.org/10.1142/9789814322119_0011.

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Lin, Huibin, Jianqun Lin, and Jianqiang Lin. "The effects of different host plants on the components and DNA of the herbal plants ofCuscuta." In International conference on Human Health and Medical Engineering. Southampton, UK: WIT Press, 2014. http://dx.doi.org/10.2495/hhme130601.

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Reports on the topic "Parasitic plants Host plants"

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Aly, Radi, James H. Westwood, and Carole L. Cramer. Novel Approach to Parasitic Weed Control Based on Inducible Expression of Cecropin in Transgenic Plants. United States Department of Agriculture, May 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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Aly, Radi, and John I. Yoder. Development of resistant crop plants to parasitic weeds based on trans-specific gene silencing. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598146.bard.

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Broomrapes (Orobanche/Phelipanchespp.) are holo parasitic plants that subsist on the roots of a variety of agricultural crops and cause severe losses to the yield quality and quantity. Effective methods for controlling parasitic weeds are scarce, with only a few known cases of genetic resistance. In the current study, we proposed an improved strategy for the control of parasitic weeds based on trans-specific gene-silencing of three parasite genes at once. We used two strategies to express dsRNA containing selected sequences of three Phelipancheaegyptiacagenes PaACS, PaM6PR and PaPrx1 (pma): transient expression using Tobacco rattle virus (TRV:pma) as a virus-induced gene-silencing (VIGS) vector and stable expression in transgenic tomato Solanumlycopersicum(Mill.) plants harboring a hairpin construct (pBINPLUS35:pma). siRNA-mediated transgene-silencing (20–24 nt) was detected in the host plants. Our results demonstrate that the quantities of PaACSand PaM6PR transcripts from P. aegyptiacatubercles grown on transgenic tomato or on Tobacco rattle virus-infected Nicotianabenthamianaplants were significantly reduced. However, only partial reductions in the quantity of PaPrx1 transcripts were observed in the parasite tubercles grown on tomato and on N. benthamianaplants. Concomitant with the suppression of the target genes, there were significant decreases in the number and weight of the parasite tubercles that grew on the host plants, in both the transient and the stable experimental systems. The results of the work carried out using both strategies point to the movement of mobile exogenous siRNA from the host to the parasite, leading to the impaired expression of essential parasite target genes. In light of the importance of parasitic weeds to world agriculture and the difficulty of obtaining resistance by conventional methods, we assume that genetic resistance based on the silencing of key metabolic genes in the parasite is now feasible. BARD Report - Project4622 Page 2 of 60
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Westwood, James H., Yaakov Tadmor, and Hanan Eizenberg. Identifying the genes involved in host root perception by root parasitic weeds: Genetic and transcriptomic analysis of Orobanche hybrids differing in signal response specificity. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598145.bard.

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Seeds of the root parasitic plants of the genus Orobanchegerminate specifically in response to host-derived germination signals, which enables parasites to detect and attack preferred hosts. The best characterized class of germination stimulants is the strigolactones (SL), although some species respond to sesquiterpene lactones such as dehydrocostuslactone (DCL). Despite great progress in characterizing the SL signaling system in plants, the mechanism(s) by which parasite species detect specific compounds remains poorly understood. The goal of our project was to identify and characterize the genes responsible for stimulant specificity in O. cernuaand O. cumana. These two species are closely related, but differ in host range, with O. cernuaparasitizingSolanaceous crops such as tomato (and responding to SLs), and O. cumanaspecifically parasitizing sunflower (and responding to DCL). We used a genetic approach based on O. cernuax O. cumanahybrids to associate germination response with genes. We found that these parasite species each have multiple copies of KAI2d genes, which function in SL perception. In O. cernua, the OrceKAI2d2 responds to SL stimulants and is most consistently associated with hybrid lines that respond to SLs. For O. cumana, an apparently linked block of KAI2d genes was associated with response to DCL in hybrid lines, but we found no strong evidence that any of the OrcuKAI2d genes specifically recognize the DCL stimulant. Remarkably, one O. cumanagene, OrcuKAI2d5, responds to certain SLs in a genetic complementation assay, even though hybrid lines containing this gene show fidelity to DCL. In summary, we have identified the SL receptor in O. cernua, but the DCL receptor in O. cumanaremains unknown. Our data point to involvement of additional genes and yet greater levels of complexity regulating germination specificity in Orobanche. BARD Report - Project 4616 Page 2 of 8
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Phillips, Donald A., Yitzhak Spiegel, and Howard Ferris. Optimizing nematode management by defining natural chemical bases of behavior. United States Department of Agriculture, November 2006. http://dx.doi.org/10.32747/2006.7587234.bard.

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This project was based on the hypothesis that nematodes interacting with plants as either parasites or beneficial saprophytes are attracted to their host by natural products. This concept was supported by numerous observations that parasitic nematodes are attracted to root exudates. Our overall goal was to identify nematode sensory compounds from root exudates and to use that information for reducing nematicide applications. We applied skills of the investigators to achieve three specific objectives: 1) Identify nematode behavioral cues (e.g., attractants or repellents) in root exudates; 2) Identify new natural nematicidal compounds; and 3) Combine a natural attractant and a nematicide into a nematode trap. Because saprophytic nematodes benefit plants by mineralizing organic matter, we sought compounds attractive primarily to parasitic nematodes. The project was constructed on several complementary foundations. First, data from Dr. Spiegel’s lab showed that under aseptic conditions Ditylenchus dipsaci, a parasite on onion, is attracted to certain fractions of onion root exudates. Second, PI Phillips had a sizeable collection of natural plant products he had identified from previous work on Rhizobium-legume interactions, which could be tested “off the shelf”. Third, Dr. Ferris had access to aseptic and natural populations of various saprophytic and parasitic nematodes. The project focused on five nematode species: D.dipsaci, Heterodera avenae, and Tylenchulussemipenetransat ARO, and Meloidogyne javanicand Caenorhabditis elegans at UCD. Ten pure plant compounds, mostly flavonoids, were tested on the various nematode species using six different assay systems. Results obtained with assorted test systems and by various scientists in the same test systems were essentially irreproducible. Many convincing, Many convincing, i.e. statistically significant, results in one system or with one investigator could not be repeated with other assays or different people. A recent report from others found that these compounds, plus another 30, were inactive as attractants in three additional parasitic nematode species (Wuyts et al. Nematology 8:89- 101, 2006). Assays designed to test the hypothesis that several compounds together are required to attract nematodes have thus far failed to find a reproducibly active combination. In contrast to results using pure plant compounds, complex unfractionated exudates from aseptic onion root reproducibly attracted D. dipsaci in both the ARO and UCD labs. Onion root exudate collection, separation into HPLC fractions, assays using D. dipsaci and MS-MS experiments proceeded collaboratively between ARO and UCD without any definitive identification of an active compound. The final active fraction contained two major molecules and traces of several other compounds. In the end, analytical studies were limited by the amount of onion root exudate and the complexity of the purification process. These tests showed that aseptic plant roots release attractant molecules, but whether nematodes influence that release, as insects trigger release of attractants from plants, is unknown. Related experiments showed that the saprophyte C. elegans stimulates its prey, Pseudomonas bacteria, to increase production of 2, 4-diacetylphloroglucinol (DAPG) a compound that promotes amino acid exudation by plant roots. It is thus possible that saprophytic nematodes are attracted primarily to their bacterial or fungal prey and secondarily to effects of those microorganisms on root exudation. These observations offer promising avenues for understanding root-zone interactions, but no direct routes to controlling nematodes in agriculture were evident. Extracts from two plant sources, Chrysanthemum coronarium and Sequoia sempervirens, showed nematicidal activity at ARO and UCD, respectively. Attempts to purify an active compound from S. sempervirens failed, but preliminary results from C. coronarium are judged to form a potential basis for further work at ARO. These results highlight the problems of studying complex movement patterns in sentient organisms like nematodes and the issues associated with natural product isolation from complex mixtures. Those two difficulties combined with complications now associated with obtaining US visas, slowed and ultimately limited progress on this project. As a result, US investigators expended only 65% of the $207,400 originally planned for this project. The Israeli side of the project advanced more directly toward its scientific goals and lists its expenditures in the customary financial report.
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Houck, Marilyn, Uri Gerson, and Robert Luck. Two Predator Model Systems for the Biological Control of Diaspidid Scale Insects. United States Department of Agriculture, June 1994. http://dx.doi.org/10.32747/1994.7570554.bard.

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Hemisarcoptes (Acari: Hamisarcoptidae) is a parasite of scale insects (Diaspididae), tenacious pests of vascular plants. Hemisarcoptes also has a stenoxenic phoretic (dispersal) relationship with Chilocorus (Coleoptera: Coccinellidae). Chilocorus feeds on diaspidids, transports mites as they feed, and has been applied to the control of scales, with limited success. U.S.-Israeli cooperation focused on this mite-beetle interaction so that a two-component system could be applied to the control of scale insects effectively. Life history patterns of Hemisarcoptes were investigated in response to host plant type and physical parameters. Field and lab data indicated that mites attack all host stages of scales tested, but preferred adult females. Scale species and host plant species influenced the bionomics of Hemisarcoptes. Beetle diet also influenced survival of phoretic mites. Mites use a ventral sucker plate to extract material from Chilocorus, that is essential for development. Seven alkaloids were found in the hemolymph of Chilocorus and three were characterized. Examination of the subelytral surface of Chilocorus indicated that microsetae play a role in the number and distribution of mites a beetle transports. While Hemisarcoptes can be innoculatd into agroecosystems using various indigenous or imported Chilocorus species, the following are preferred: C. bipustulatus, C. cacti, C. distigma, C. fraternus, C. orbus, and C. tristis.
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McClure, Michael A., Yitzhak Spiegel, David M. Bird, R. Salomon, and R. H. C. Curtis. Functional Analysis of Root-Knot Nematode Surface Coat Proteins to Develop Rational Targets for Plantibodies. United States Department of Agriculture, October 2001. http://dx.doi.org/10.32747/2001.7575284.bard.

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The goal of this research was to provide a better understanding of the interface between root-knot nematodes, Meloidogyne spp., and their host in order to develop rational targets for plantibodies and other novel methods of nematode control directed against the nematode surface coat (SC). Specific objectives were: 1. To produce additional monoclonal SC antibodies for use in Objectives 2, 3, and 4 and as candidates for development of plantibodies. 2. To determine the production and distribution of SC proteins during the infection process. 3. To use biochemical and immunological methods to perturbate the root-knot nematode SC in order to identify SC components that will serve as targets for rationally designed plantibodies. 4. To develop SC-mutant nematodes as additional tools for defining the role of the SC during infection. The external cuticular layer of nematodes is the epicuticle. In many nematodes, it is covered by a fuzzy material termed "surface coat" (SC). Since the SC is the outermost layer, it may playa role in the interaction between the nematode and its surroundings during all life stages in soil and during pathogenesis. The SC is composed mainly of proteins, carbohydrates (which can be part of glycoproteins), and lipids. SC proteins and glycoproteins have been labeled and extracted from preparasitic second-stage juveniles and adult females of Meloidogyne and specific antibodies have been raised against surface antigens. Antibodies can be used to gain more information about surface function and to isolate genes encoding for surface antigens. Characterization of surface antigens and their roles in different life-stages may be an important step towards the development of alternative control. Nevertheless, the role of the plant- parasitic nematode's surface in plant-nematode interaction is still not understood. Carbohydrates or carbohydrate-recognition domains (CROs) on the nematode surface may interact with CROs or carbohydrate molecules, on root surfaces or exudates, or be active after the nematode has penetrated into the root. Surface antigens undoubtedly play an important role in interactions with microorganisms that adhere to the nematodes. Polyclonal (PC) and monoclonal (MC) antibodies raised against Meloidogyne javanica, M. incognita and other plant-parasitic nematodes, were used to characterize the surface coat and secreted-excreted products of M. javanica and M. incognita. Some of the MC and PC antibodies raised against M. incognita showed cross-reactivity with the surface coat of M. javanica. Further characterization, in planta, of the epitopes recognized by the antibodies, showed that they were present in the parasitic juvenile stages and that the surface coat is shed during root penetration by the nematode and its migration between root cells. At the molecular level, we have followed two lines of experimentation. The first has been to identify genes encoding surface coat (SC) molecules, and we have isolated and characterized a small family of mucin genes from M. incognita. Our second approach has been to study host genes that respond to the nematode, and in particular, to the SC. Our previous work has identified a large suite of genes expressed in Lycopersicon esculentum giant cells, including the partial cDNA clone DB#131, which encodes a serine/threonine protein kinase. Isolation and predicted translation of the mature cDNA revealed a frame shift mutation in the translated region of nematode sensitive plants. By using primers homologous to conserved region of DB#131 we have identified the orthologues from three (nematode-resistant) Lycopersicon peruvianum strains and found that these plants lacked the mutation.
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7

Rodriguez, Russell, and 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, February 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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8

Freeman, Stanley, and Russell J. Rodriguez. The Interaction Between Nonpathogenic Mutants of Colletotrichum and Fusarium, and the Plant Host Defense System. United States Department of Agriculture, September 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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9

Spiegel, Yitzhak, B. M. Zuckerman, Eli Cohn, and Itzhak Kahane. Control of Plant Parasitic Nematodes by Intervention in the Host-Finding Process. United States Department of Agriculture, July 1986. http://dx.doi.org/10.32747/1986.7566724.bard.

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10

Brown Horowitz, Sigal, Eric L. Davis, and Axel Elling. Dissecting interactions between root-knot nematode effectors and lipid signaling involved in plant defense. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598167.bard.

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Root-knot nematodes, Meloidogynespp., are extremely destructive pathogens with a cosmopolitan distribution and a host range that affects most crops. Safety and environmental concerns related to the toxicity of nematicides along with a lack of natural resistance sources threaten most crops in Israel and the U.S. This emphasizes the need to identify genes and signal mechanisms that could provide novel nematode control tactics and resistance breeding targets. The sedentary root-knot nematode (RKN) Meloidogynespp. secrete effectors in a spatial and temporal manner to interfere with and mimic multiple physiological and morphological mechanisms, leading to modifications and reprogramming of the host cells' functions, resulted in construction and maintenance of nematodes' feeding sites. For successful parasitism, many effectors act as immunomodulators, aimed to manipulate and suppress immune defense signaling triggered upon nematode invasion. Plant development and defense rely mainly on hormone regulation. Herein, a metabolomic profiling of oxylipins and hormones composition of tomato roots were performed using LC-MS/MS, indicating a fluctuation in oxylipins profile in a compatible interaction. Moreover, further attention was given to uncover the implication of WRKYs transcription factors in regulating nematode development. In addition, in order to identify genes that might interact with the lipidomic defense pathway induced by oxylipins, a RNAseq was performed by exposing M. javanicasecond-stage juveniles to tomato protoplast, 9-HOT and 13-KOD oxylipins. This transcriptome generated a total of 4682 differentially expressed genes (DEGs). Being interested in effectors, we seek for DEGs carrying a predicted secretion signal peptide. Among the DEGs including signal peptide, several had homology with known effectors in other nematode species, other unknown potentially secreted proteins may have a role as root-knot nematodes' effectors which might interact with lipid signaling. The molecular interaction of LOX proteins with the Cyst nematode effectors illustrate the nematode strategy in manipulating plant lipid signals. The function of several other effectors in manipulating plant defense signals, as well as lipids signals, weakening cell walls, attenuating feeding site function and development are still being studied in depth for several novel effectors. As direct outcome of this project, the accumulating findings will be utilized to improve our understanding of the mechanisms governing critical life-cycle phases of the parasitic M. incognita RKN, thereby facilitating design of effective controls based on perturbation of nematode behavior—without producing harmful side effects. The knowledge from this study will promote genome editing strategies aimed at developing nematode resistance in tomato and other nematode-susceptible crop species in Israel and the United States.
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