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Auswahl der wissenschaftlichen Literatur zum Thema „Host/non-Host“
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Zeitschriftenartikel zum Thema "Host/non-Host"
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Anderson, John R. „Host Specific Cephenemyia of Deer Repelled by Non-Host Odors“. Journal of Insect Behavior 25, Nr. 6 (20.04.2012): 620–30. http://dx.doi.org/10.1007/s10905-012-9330-z.
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Groisman, Eduardo A., und Chakib Mouslim. „Sensing by bacterial regulatory systems in host and non-host environments“. Nature Reviews Microbiology 4, Nr. 9 (07.08.2006): 705–9. http://dx.doi.org/10.1038/nrmicro1478.
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Schafer, W., und O. C. Yoder. „Organ specificity of fungal pathogens on host and non-host plants“. Physiological and Molecular Plant Pathology 45, Nr. 3 (September 1994): 211–18. http://dx.doi.org/10.1016/s0885-5765(05)80078-5.
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Li, Hua, Xintian Ge, Shiue Han, Krishnapillai Sivasithamparam und Martin John Barbetti. „Histological responses of host and non-host plants to Hyaloperonospora parasitica“. European Journal of Plant Pathology 129, Nr. 2 (17.09.2010): 221–32. http://dx.doi.org/10.1007/s10658-010-9664-3.
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Bains, S. S., und H. S. Dhaliwal. „Production of Neovossia indica sporidia on host and non-host plants“. Plant and Soil 126, Nr. 1 (August 1990): 85–89. http://dx.doi.org/10.1007/bf00041372.
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Cusumano, Antonino, Jeffrey A. Harvey, Marcel Dicke und Erik H. Poelman. „Hyperparasitoids exploit herbivore-induced plant volatiles during host location to assess host quality and non-host identity“. Oecologia 189, Nr. 3 (05.02.2019): 699–709. http://dx.doi.org/10.1007/s00442-019-04352-w.
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Ballabeni, Pierluigi, und Martine Rahier. „Performance of leaf beetle larvae on sympatric host and non-host plants“. Entomologia Experimentalis et Applicata 97, Nr. 2 (November 2000): 175–81. http://dx.doi.org/10.1046/j.1570-7458.2000.00728.x.
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Giovannetti, M., L. Lioi und G. Picci. „Host and non-host relationships between Arbutus unedo L. And mycorrhizal fungi“. Agriculture, Ecosystems & Environment 29, Nr. 1-4 (Februar 1990): 169–72. http://dx.doi.org/10.1016/0167-8809(90)90271-e.
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Allen, Ryan M., Corey A. Scipione, Marlys L. Koschinsky und Kasey C. Vickers. „Lipoprotein(a) Transports Diverse Host and Non-Host Small RNAs in Circulation“. Atherosclerosis Supplements 32 (Juni 2018): 63. http://dx.doi.org/10.1016/j.atherosclerosissup.2018.04.189.
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DE RIJK, MARJOLEIN, VICTOR CEGARRA SÁNCHEZ, HANS M. SMID, BAS ENGEL, LOUISE E. M. VET und ERIK H. POELMAN. „Associative learning of host presence in non-host environments influences parasitoid foraging“. Ecological Entomology 43, Nr. 3 (13.01.2018): 318–25. http://dx.doi.org/10.1111/een.12504.
Der volle Inhalt der QuelleDissertationen zum Thema "Host/non-Host"
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Kingdom, Heather. „AY-WB phytoplasma manipulations of host and non-host leafhopper interactions“. Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/40581/.
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In plant hosts, phytoplasmas induce physiological changes and in both hosts modulate plant-insect interactions. Previously, interactions have been examined with both hosts infected with phytoplasmas. Thus, it is unclear which organism the effect stems from or how phytoplasmas facilitate changes. To investigate phytoplasma manipulations of insect-plant interactions, the model Arabidopsis thaliana was used together with the fully sequenced Aster Yellows phytoplasma strain Witches’ Broom (AY-WB) and vector leafhopper Macrosteles quadrilineatus. I demonstrate possibility to differentiate effects of phytoplasma infection within plant and within insect hosts. To assess root cause of changes, AY-WB secreted effector proteins were examined, their roles within plants, and in manipulations of vector fecundity. One of the 56 secreted AY-WB proteins (SAPs) identified, SAP11, carries a nuclear localization signal and accumulates in plant cell nuclei (Bai et al. 2009). SAP11 is shown to reduce production of plant defense hormone jasmonic acid (Sugio et al. 2011). Stable expression of SAP11 and 3 other SAPs in Arabidopsis increase fecundity of M. quadrilineatus. In addition, phytoplasmas are known to affect non-host insect-plant interactions. Using the same approach, I demonstrate D. maidis survives and produces nymphs only on AY-WB-infected Arabidopsis. Furthermore, I show that whilst SAP11 has no effect on D. maidis survival, 3 other SAPs increase D. maidis survival and oviposition. These data suggest phytoplasmas utilize a suite of effector proteins to manipulate both host and non-host insect-plant interactions. Thus, AY-WB effector functions extend beyond direct interaction with plant hosts; they stimulate generation of insect vectors, and increase chance of uptake by novel insect hosts. This project highlights the value of using a model system in studying phytoplasma manipulation of their hosts and gives insight into development of evolutionary associations between phytoplasmas and vectors.
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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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Sydorchuk, R. I. „Non-specific host resistance in acute trauma“. Thesis, БДМУ, 2021. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18659.
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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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Shafiei-Adjbisheh, Reza. „Genetic analysis of Arabidopsis non-host disease resistance“. Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/14381.
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Significant differences were observed among 79 geographically diverse Arabidopsis accessions in response to the wheat powdery mildew pathogen, Blumeria graminis f.sp. tritici (Bgt) and the wheat leaf rust pathogen Puccinia triticina (Ptr). In response to Bgt genotypes classified into two major classes based on the degree of compatibility, Wc-1 an accession from Germany expressed significantly high frequency of penetration. Interestingly, in response to Ptr, a high frequency of guard cell death and sub-stomata vesicle formation (SVF) was observed on Wa-1, an accession from Poland. Attempted Ptr infection induced the production of reaction oxygen intermediates (ROI), nitric oxide, salicylic acid (SA) and camalexin. The expression of SA, jasmonic acid and ROI-dependent genes were also detected. Multiple small-to-medium effect quantitative trait loci (QTL) were identified that govern the expression of NMR in Arabidopsis against Ptr. In response to Bgt, a leaf collapse phenotype was observed in Ler when it was pre-treated with Cytochalasin E, an inhibitor of actin microfilament polymerization. Whereas, Col did not express a similar phenotype. This reaction showed a complicated genetic basis with the involvement of several genes. Our genetic analysis revealed two major QTLs on chromosomes one and three with the existence of episatsis effects. A role for ASYMMETRIC LEAVES1 (AS1) in plant immunity has recently been identified. My experiments showed a conserved regulatory function for NSPHAN, an orthologue of ASI gene in Nicotiana sylvestris when challenged with host and nonhost pathogens. This regulatory gene action remained consistent when the as1 mutant was coupled with key Arabidopsis defence related mutants.
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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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Ward, Rebecca. „Bluetongue virus non-structural protein 1 : virus-host interactions“. Thesis, London School of Hygiene and Tropical Medicine (University of London), 2006. http://researchonline.lshtm.ac.uk/4646527/.
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Bluetongue virus (BTY) is an orbivirus of the Reoviridae family that infects sheep and other ruminants. BTY has three non-structural proteins, NS I, NS2 and NS3/3A. NS I forms tubular structures and its function is currently unknown. To investigate the role of NS I in BTY infection, the interactions of NS I with mammalian and insect cellular proteins, and BTY viral proteins, were examined. BTY NS I was identi tied as interacting with aldolase A, NUBP 1, Pyruvate kinase M2, cathespin B, SUM 0-1 and peptide TY7 using the yeast two-hybrid system, ELISA and immunofluorescence analysis. TY7 and NS I caused extensive cell death within 24h of co-expression; this cell death was not apoptosis and reduced BTY yield by 37%. The interaction of NS I with SUMO-I and its importance in BTY infection was confinned using siRNA to knockdown SUMO-I during BTY-IO infection. Knockdown of SUMO-I elicited a dramatic reduction in virus yield by 73%. NS I interactions with proteins of the insect vector Culicoides were also examined. A putative interaction between NS 1 and the ubiquitin activating enzyme El (UBA EI) ofCulicoides was identified during screening of a phage library, this has not been confirmed by other means. NS 1 interactions with other BTY proteins were analysed using immunoprecipitation and a strong interaction between NS 1 and YP7 was identified; this was confim1ed using the yeast two-hybrid system and immunoflourescence. Two main roles have been hypothesised for NS I from this data; firstly it is likely that NS I interaction with SUMO-I and UBA E I allows the targeting of specific proteins for sumoylation and ubiquitination allowing NS 1 to modify the host response to BTY infection. Secondly it is possible that NS I serves as an anchor for YP7 and virus cores allowing the build up of cores at the cytoskeleton in close proximity to YP2 for subsequent assembly and release. RNAi against NS J eliminated tubule formation but did not affect virus yield or YP7 and SUMO-J distribution and expression. It is therefore likely that the function of NS I does not rely on tubule fom1ation and that tubules are a form of storage for the active monomer of NSI.
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Rodrigues, Paula. „Identification of non-host resistance genesin wheat to Puccinia striiformis f. sp. hordei“. Master's thesis, Universidade de Trás-os-Montes e Alto Douro, 2004. http://hdl.handle.net/10198/934.
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Yellow rust, caused by Puccinia striiformis West., is an important foliar disease of wheat and barley throughout the world, and the development of resistant cultivars is the most economical and environmentally friendly method of control. Breeding for resistance to yellow rust has, for decades, been based on the use of race-specific resistance genes, which have shown to be short-lived. Non-host resistance has been studied as a possible source of durable resistance.
Two major genes, as well as an undetermined number of minor genes, for non-host resistance to the barley attacking form of yellow rust, P. striiformis f. sp. hordei, have been previously detected in the wheat cultivar ‘Lemhi’. The present study aimed at quantifying and mapping those genes using QTL (quantitative trait loci) mapping procedures. For that purpose, an F2 population of 114 individuals resulting from the cross of resistant ‘Lemhi’ with ‘Chinese 166’, a wheat cultivar susceptible to barley yellow rust, was used as the mapping population. QTL effects and significance were estimated by means of interval mapping and MQM mapping procedures.
A map for the F2 population was constructed which included 116 DNA markers (14 SSRs and 102 AFLPs). Two major QTLs have been mapped to chromosome arms 1DS (Psh1) and 2BL (Psh2), with significant LOD values. These two QTLs account for 76.7% of the phenotypic variance for resistance to barley yellow rust. Two other QTLs, with a minor effect, were mapped to chromosome arms 5AL (Psh3) and 6AL (Psh4), explaining 5.1% and 10.9% of the phenotypic variation, respectively. The QTL on 5A was derived from the susceptible variety, ‘Chinese 166’. In all cases the resistance towards P. striiformis f.sp. hordei was associated with a visual chlorosis/necrosis response typical of race-specific, host resistance.A ferrugem amarela, cujo agente causal é Puccinia striiformis Westend, é uma doença particularmente importante nas produções de trigo e cevada em todo o mundo, principalmente em regiões de clima fresco e húmido (EVERSMEYER & KRAMER, 2000). Infecções severas deste patogénio podem causar drásticas reduções na altura da planta, no número de grãos por espiga, e no peso e qualidade dos grãos (MA & SINGH, 1996b). A espécie P. striiformis encontra-se dividida em formae speciales, em função do género vegetal que ataca. Por exemplo, o trigo é considerado hospedeiro para P. striiformis f. sp. tritici, a ferrugem amarela do trigo, mas não para a f. sp. hordei, a forma da ferrugem amarela que ataca a cevada. No entanto, a divisão de P. striiformis em formae speciales, e em particular a separação em f. sp. tritici e f. sp. hordei, tem sido fortemente questionada, uma vez que existem vários exemplos de formae speciales com capacidade de atacar genótipos de espécies que estão supostamente fora do seu leque de hospedeiros (hospedeiros ‘inapropriados’) (JOHNSON & LOVELL, 1994; CHEN et al., 1995). O desenvolvimento de cultivares resistentes à ferrugem amarela é actualmente considerado o melhor método de controlo da doença, tanto a nível económico como ambiental. No entanto, o melhoramento para a resistência a esta doença tem assentado, ao longo das últimas décadas, no uso de genes de resistência específica de planta hospedeira, que, na maioria dos casos, têm demonstrado baixa durabilidade (WELLINGS & MCINTOSH, 1990; BAYLES et al., 2000; SING & HUERTA-ESPINO, 2001). O uso generalizado de cultivares portadoras deste tipo de resistência resulta geralmente numa elevada pressão de selecção sobre o patogénio e na sua consequente evolução para novas formas de virulência (BROWN, 1995). Formas de resistência alternativas à resistência específica têm sido estudadas como possíveis fontes de resistência durável. A resistência de planta não hospedeira é considerada por vários autores, a forma mais eficaz de obter durabilidade (HEATH, 1991; CRUTE & PINK, 1996). Na sua generalidade, este tipo de resistência envolve um controlo genético complexo e uma multiplicidade de factores de defesa que impedem o microrganismo de formar uma interacção básica (compatível) com a planta (HEATH, 1991). No entanto, interacções não-hospedeiro entre espécies vegetais filogeneticamente próximas (como é o caso do trigo e da cevada) e formae speciales do mesmo patogénio (P. striiformis f. sp. hordei e P. striiformis f. sp. tritici) parecem envolver mecanismos de resistência semelhantes aos envolvidos na resistência específica de planta hospedeira, que geralmente estão associados ao retardamento do desenvolvimento do patogénio na fase pós-haustorial e à morte das células invadidas (reacção de hipersensibilidade) (NIKS, 1988; GARROOD, 2001). As estratégias de exploração da resistência de planta não hospedeira, assim como a sua durabilidade efectiva, irão, neste sentido, depender de a resistência ser controlada por mecanismos de defesa específicos ou não-específicos (HEATH, 2001). Torna-se, portanto, indispensável a existência de informação detalhada sobre os genes que controlam os mecanismos de resistência de planta não hospedeira, por forma a determinar a viabilidade do uso deste tipo de resistência como fonte de resistência durável. O progresso nos sistemas de marcadores moleculares de DNA e nos programas informáticos de análise genética tornou possível o mapeamento de genes e a identificação de QTLs (Quantitative Trait loci, loci para características quantitativas) com relativa precisão, o que permitiu uma revisão dos métodos de análise genética e das estratégias de melhoramento. A análise de QTLs, i.e., a dissecção genética de características quantitativas, atenta na determinação do número de loci envolvidos na resistência, assim como na localização no genoma da planta e contribuição para o fenótipo de cada um desses loci, através da associação entre a variação de marcadores genéticos numa população segregante e a variação fenotípica para a resistência apresentada por essa mesma população (MOHAN et al., 1997). A tecnologia de microsatélites ou SSRs (Simple Sequence Repeats, repetições de sequências simples), que consistem em repetições em tandem de motivos básicos de 2 a 6 bases (TAUTZ, 1989), emergiu na última década como o sistema de escolha no mapeamento molecular em plantas, e em particular no trigo. Tal ocorre devido ao elevado número de SSRs existente nos genomas das plantas, e porque nesta tecnologia se reúnem as principais vantagens dos diferentes sistemas de marcadores moleculares: são específicos do cromossoma, altamente informativos, co-dominantes, com uma boa cobertura do genoma e com elevado potencial de automatização (MORGANTE & OLIVIERI, 1993; RÖDER et al., 1995; POWELL et al., 1996a; KORZUN et al., 1997). Têm como principal inconveniente o elevado custo de identificação e produção (POWELL et al., 1996a). Vários mapas de ligação foram já desenvolvidos para o trigo baseados neste tipo de marcadores moleculares (DEVOS et al., 1995; PLASCHKE et al., 1995; RÖDER et al., 1995, 1998a, b; BRYAN et al., 1997; STEPHENSON et al., 1998; PESTSOVA et al., 2000; VARSHNEY et al., 2000; SOURDILLE et al., 2001; GUPTA et al., 2002), e têm sido amplamente usados na localização de genes e QTLs responsáveis por resistências a doenças, incluindo a resistência à ferrugem amarela (e.g. CHAGUÉ et al., 1999; PENG et al., 1999, 2000a, b; BOUKHATEM et al., 2002; SUN et al., 2002). Com base num cruzamento entre as cultivares de trigo ‘Lemhi’ (resistente à ferrugem amarela da cevada) e ‘Chinese 166’ (susceptível à doença), JOHNSON & LOVELL (1994) identificaram dois genes major, independentes e dominantes, responsáveis pela resistência de planta não hospedeira à ferrugem amarela da cevada na cv. ‘Lemhi’. Foi igualmente detectada a existência de um número indeterminado de genes minor, alguns dos quais com possível origem na cv. ‘Chinese 166’. Pretendeu-se com o presente trabalho: 1) desenvolver um mapa genético para uma população F2, constituída por 114 indivíduos, derivada do cruzamento ‘Lemhi’ x ‘Chinese 166’ usando marcadores do tipo SSR; 2) adicionar estes marcadores a um mapa de AFLPs previamente construído para a mesma população; e 3) localizar os genes responsáveis pela resistência do trigo à ferrugem amarela da cevada em segregação na população F2 ‘Lemhi’ x ‘Chinese 166’. Cento e dezoito indivíduos da população F2 ‘Lemhi’ x ‘Chinese 166’, assim como as plantas progenitoras desta população, foram previamente testados para resistência/susceptibilidade ao referido patogénio. ‘Lemhi’ apresentou um fenótipo totalmente resistente, enquanto ‘Chinese 166’ se apresentou moderadamente susceptível, o que confirmou a presença de gene(s) minor nesta cultivar. Os 118 indivíduos da F2 analisados fenotipicamente segregaram 115 resistentes : 3 susceptíveis, sugerindo que a resistência de ‘Lemhi’ à ferrugem amarela é efectivamente controlada por dois genes major. Foram testados 88 pares de primers de SSRs para a presença de polimorfismos entre ‘Lemhi’ e ‘Chinese 166’. Desta análise resultou um total de 41 SSRs polimórficos, que foram analisados em 114 indivíduos da população F2. Com base nestes SSRs e em 172 AFLPs (Amplified Fragment Length Polymorphisms, polimorfismos do comprimento dos fragmentos amplificados) anteriormente desenvolvidos para a mesma população, e recorrendo ao programa informático de análise genética JoinMap® versão 3.0 (VAN OOIJEN & VOORRIPS, 2001), foi construído um mapa molecular com 18 mapas de ligação, integrando 116 marcadores de DNA (14 SSRs e 102 AFLPs), e abrangendo 680 cM, com uma densidade média de 1 marcador por cada 6 cM. Os restantes 97 marcadores moleculares não foram integrados no mapa, provavelmente por, dada a extensão do genoma do trigo, não haver marcadores suficientes para criar ligação entre eles. Oito dos 18 grupos de ligação foram ancorados a seis cromossomas (1D, 2B, 3A, 5A, 6A e 6B) pela presença de SSRs. Uma vez que os restantes grupos de ligação não foram associados a nenhum QTL (ver parágrafo seguinte), não foram desenvolvidos esforços no sentido de identificar SSRs específicos para esses grupos de ligação. A identificação de QTLs foi efectuada usando o programa informático de análise de QTLs MapQTL™ versão 4.0 (VAN OOIJEN et al., 2002). Os efeitos dos QTLs e a sua significância para a variação fenotípica total da resistência à ferrugem amarela da cevada foram estimados pelos métodos Interval Mapping e MQM Mapping. Através do método Interval Mapping foram identificados dois QTLs major, localizados nos cromossomas 1DS (Psh1) e 2BL (Psh2), com origem na cv. ‘Lemhi’. Por forma a detectar possíveis QTLs minor mascarados por estes QTLs major, foi aplicado o método MQM Mapping. Neste método, recorre-se ao uso dos marcadores que flanqueiam os QTLs detectados por Interval Mapping como co-factores para eliminar o efeito daqueles e detectar QTLs minor. Após análise por MQM Mapping, foram localizados dois QTLs minor nos cromossomas 5AL (Psh3) e 6AL (Psh4), sendo que o QTL presente no cromossoma 5A deriva da variedade susceptível ‘Chinese 166’. Os quatro QTLs detectados explicam, no seu conjunto, 92,7% da variação fenotípica total da resistência à doença, o que indica que, provavelmente, todos os loci que contribuem para a resistência de planta não hospedeira foram identificados. Neste estudo, verificou-se que a resistência à ferrugem amarela da cevada estava associada a uma resposta fenotípica de clorose/necrose, típica de resistência específica de planta hospedeira. Para além disso, os genes Psh1 e Psh2, genes de resistência de planta não hospedeira à ferrugem amarela da cevada, foram identificados em regiões do genoma do trigo onde se pensa (no caso do Psh1) e onde se sabe (no caso de Psh2) existirem genes de resistência de planta hospedeira (genes Yr) à ferrugem amarela do trigo. Tendo em atenção estes factos, pode considerar-se a possibilidade de uma ligação entre genes Psh e genes Yr, que, a confirmar-se, pode levar a supor que se trata de genes que evoluíram de um mesmo gene de resistência ancestral, possuindo portanto estrutura e modo de acção semelhantes. Se tal se vier a verificar, então a durabilidade de ambos seria, também ela, semelhante. Patologistas e melhoradores teriam que repensar seriamente a validade da busca de genes de resistência de planta não hospedeira como fonte de resistência durável. A clonagem destes genes é, neste sentido, essencial para que estudos bioquímicos e de funcionamento dos genes possam ser posteriormente desenvolvidos, e para que seja determinada a viabilidade do uso dos genes Psh como genes de resistência com efeito duradouro.
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Aucique, Pérez Carlos Eduardo. „Wheat resistance to blast using a non-host selective toxin and host metabolic reprogramming through a successful infection by Pyricularia oryzae“. Universidade Federal de Viçosa, 2016. http://www.locus.ufv.br/handle/123456789/21193.
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A brusone, causada por Pyricularia oryzae, é considerada uma doença economicamente importante para trigo na América do Sul. Uma das estratégias de manejo para minimizar as perdas causadas por essa doença é o uso de cultivares resistentes. Alternativamente, pode-se utilizar indutores de resistência para aumentar o nível basal de resistência do trigo à brusone. O presente estudo teve como objetivos: i) determinar as alterações fisiológicas e bioquímicas em plantas de trigo pulverizadas com uma concentração não fitotóxica do ácido α-picolinico (AP), o qual é uma toxina não seletiva produzida por P. oryzae e ii) verificar a manipulação metabólica exercido por P. oryzae quando infectando cultivares de trigo com diferentes níveis de resistência basal à brusone. Nas folhas de trigo pulverizadas com uma concentração não fitotóxica de AP (0.1 mg mL -1 ), os sintomas da brusone desenvolveram menos em associação com um melhor desempenho fotossintético, melhoria do metabolismo antioxidante e redução nas concentrações de H 2 O 2 , O 2 ●- e MDA. As cultivares BR-18 e EMBRAPA- 16 foram mais resistentes à brusone do que a cultivar BRS-Guamirim. O desempenho fotossintético das plantas infectadas foi alterado devido a limitações de natureza difusiva e bioquímica para uma eficiente fixação do CO 2 . Durante a fase assintomática da infecção por P. oryzae, mudanças drásticas no metabolismo de carboidratos e nos níveis de aminoácidos, compostos intermediários do ciclo de Krebs e poliaminas ocorreram nas plantas das três cultivares sugerindo, assim, uma manipulação metabólica exercida por P. oryzae. No entanto, um metabolismo antioxidativo mais eficiente foi importante para neutralizar os efeitos deletérios da infecção por P. oryzae em associação com maiores atividades da fenilalanina amônia liase e polifenoloxidase e maiores concentrações de compostos fenólicos e lignina. Com base nesses resultados e possível concluir que a concentração não fitotóxica de AP foi capaz de potencializar a defesa das plantas de trigo e reduzir a severidade da brusone. A infecção do trigo por P. oryzae ocasionou distúrbios no metabolismo primário das plantas e alguns deles foram semelhantes entre as cultivares independentemente do nível basal de resistência delas.
Blast, caused by Pyricularia oryzae, has become an economically important disease in wheat in South America. One of the management strategies for minimizing the losses caused by blast includes the use of resistant cultivars. Alternatively, the use of inducers of resistance showed the potentiation to increase wheat resistance to blast. This study aimed: i) to determine the physiological and biochemical alterations in wheat plants sprayed with a non-phytotoxic concentration of α-picolinic acid (PA), which is a non-host selective toxin produced by P. oryzae and ii) to establish the degree of metabolic manipulation exerted during the infection by P. oryzae on plants from cultivars with different levels of basal resistance to blast. The spray of leaves of plants with a non-phytotoxic concentration of PA (0.1 mg mL -1 ) resulted in less blast symptoms in association with a better photosynthetic performance, an improvement on the antioxidant metabolism and reduced concentrations of H 2 O 2 , O 2 ●- and malondialdehyde. The cultivars BR-18 and EMBRAPA-16 were more resistant to blast in comparison to cultivar BRS-Guamirim. The photosynthetic performance of the infected plants was altered due to diffusional and biochemical limitations for CO 2 fixation. During the asymptomatic phase of P. oryzae infection, drastic changes in the carbohydrates metabolism and on the levels of amino acids, intermediates compounds of Krebs cycle and polyamines occurred on plants from the three cultivars suggesting a metabolic manipulation exerted by the pathogen. However, amore efficient antioxidant metabolism was able to help the wheat plants to counteract against the deleterious effects of P. oryzae infection in association with great phenylalanine ammonia lyases and polyphenoloxidases activities and high concentrations of phenolics and lignin. Based on this information, it is possible to conclude that a non- phytotoxic concentration of PA elicited the activation of host defense mechanisms that reduced blast severity. Likewise, the infection of leaves by P. oryzae induced remarkable disturbances in the primary metabolism and some of them were conserved among the cultivars regardless of their basal level of resistance to blast.
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Telang, M. „Molecular analysis of plant-pest interaction with special reference to helicoverpa armigera and proteinase inhibitors from host and non-host plants“. Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2006. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2524.
Der volle Inhalt der QuelleBücher zum Thema "Host/non-Host"
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Sengebau, Fernando M. Determination of non-host status for Betel Nut (Areca catechu). Palau: Bureau of Agriculture, 2004.
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Tripp, Ralph A., und S. Mark Tompkins, Hrsg. Roles of Host Gene and Non-coding RNA Expression in Virus Infection. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-05369-7.
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PhD, Henderson Brian, Hrsg. Cellular microbiology: Bacteria-host interactions in health and disease. Chichester: J. Wiley, 1999.
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Ashton, Matthew J. Freshwater mussel records collected by the Maryland Department of Natural Resources' Monitoring and Non-Tidal Assessment Division (1995-2009): Investigating environmental conditions and potential host fish of select species. Annapolis, Md: Maryland Department of Natural Resources, Resource Assessment Service, Monitoring and Non-Tidal Assessment Division, 2010.
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Adegbite, Adewale Bandele. English language usage, uses and misuse(s) in a non-host second language context, Nigeria: An inaugural lecture delivered at the Oduduwa Hall, Obafemi Awolowo University, Ile-Ife, Nigeria on Tuesday September 14, 2010. Ile-Ife, Nigeria: Obafemi Awolowo University Press Limited, 2010.
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Luong, Lien, Julia Buck, Janet Koprivnikar und Sara B. Weinstein, Hrsg. Ecology and Evolution of Non-Consumptive Effects in Host-Parasite Interactions. Frontiers Media SA, 2021. http://dx.doi.org/10.3389/978-2-88971-913-6.
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Brombacher, Frank, Abhay Satoskar und Alessandro Marcello, Hrsg. Towards Host-Directed Drug Therapies for Infectious and Non-Communicable Diseases. Frontiers Media SA, 2019. http://dx.doi.org/10.3389/978-2-88963-102-5.
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Taberlet, Pierre, Aurélie Bonin, Lucie Zinger und 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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Tripp, Ralph A., und S. Mark Tompkins. Roles of Host Gene and Non-coding RNA Expression in Virus Infection. Springer, 2019.
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Masihi, K. N. Immunomodulators and Non-Specific Host Defense Mechanisms Against Microbial Infections (Advances in the Biosciences). Pergamon, 1988.
Den vollen Inhalt der Quelle findenBuchteile zum Thema "Host/non-Host"
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Fraser, R. S. S. „Host-Range Control and Non-Host Immunity to Viruses“. In 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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Ride, J. P. „Non-Host Resistance to Fungi“. In 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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Li, Hua, Xintian Ge, Shiue Han, Krishnapillai Sivasithamparam und Martin John Barbetti. „Histological responses of host and non-host plants to Hyaloperonospora parasitica“. In 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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Durbin, Richard D. „Biochemistry of Non-Host-Selective Phytotoxins“. In ACS Symposium Series, 63–71. Washington, DC: American Chemical Society, 1990. http://dx.doi.org/10.1021/bk-1990-0439.ch003.
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Powell, Glen, Sangita P. Maniar, John A. Pickett und Jim Hardie. „Aphid responses to non-host epicuticular lipids“. In Proceedings of the 10th International Symposium on Insect-Plant Relationships, 115–23. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-017-1890-5_14.
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Schuetz, Audrey N. „Infectious Disease Biomarkers: Non-Antibody-Based Host Responses“. In Advanced Techniques in Diagnostic Microbiology, 123–49. Boston, MA: Springer US, 2012. http://dx.doi.org/10.1007/978-1-4614-3970-7_7.
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Scheel, Dierk, Christiane Colling, Harald Keller und Jane Parker. „Studies on Elicitor Recognition and Signal Transduction in Host and Non-Host Plant/Fungus Pathogenic Interactions“. In NATO ASI Series, 211–18. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74158-6_25.
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Grondeau, Catherine, und Regine Samson. „Effect of Host Genotype and Non-Host Plants on Epiphytic Life of Pseudomonas syringae pv. pisi“. In 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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de Wilde, Adriaan H., Eric J. Snijder, Marjolein Kikkert und Martijn J. van Hemert. „Host Factors in Coronavirus Replication“. In Roles of Host Gene and Non-coding RNA Expression in Virus Infection, 1–42. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/82_2017_25.
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Wu, Jian-hong, und Xue Zhang. „Impact of climate change on co-feeding transmission.“ In Climate, ticks and disease, 270–75. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789249637.0039.
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Abstract Tick-borne pathogen co-feeding transmission is a non-systemic transmission in the tick-host enzootic cycle, through which the host provides a bridge between co-feeding susceptible and infected ticks to facilitate pathogen transmission. Co-feeding transmission requires co-feeding of susceptible ticks in close (both spatially and temporally) proximity to other infected ticks on the bridging host; hence, the contribution of co-feeding transmission to tick-borne pathogen transmission in the tick-host enzootic cycle is highly affected by environmental conditions. This expert opinion focuses on co-feeding transmission and infestation dynamics of ticks under changing climate conditions.
Konferenzberichte zum Thema "Host/non-Host"
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Traynor, Patrick, Michael Chien, Scott Weaver, Boniface Hicks und Patrick McDaniel. „Non-Invasive Methods for Host Certification“. In 2006 Securecomm and Workshops. IEEE, 2006. http://dx.doi.org/10.1109/seccomw.2006.359539.
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Heikkinen, Seppo. „Non-repudiable service usage with host identities“. In Second International Conference on Internet Monitoring and Protection (ICIMP 2007). IEEE, 2007. http://dx.doi.org/10.1109/icimp.2007.28.
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Wolfin, Michael S. „Olfactory mediated responses to host- and non- host volatiles by female grape berry moths (Paralobesia viteana)“. In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.112717.
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Sun, Ang, Jaroslav Jelinek, Shinji Maegawa, Christian Jobin und Jean-Pierre Issa. „Abstract 4441: Non-pathogenic bacteria change host DNA methylationin vivo“. In Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA. American Association for Cancer Research, 2016. http://dx.doi.org/10.1158/1538-7445.am2016-4441.
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Caikauskaite, Renata, Apoorva Mulay, Derek Hood, Steve Brown, James Stewart, Lynne Bingle und Colin Bingle. „Host defence functions of BPIFA1 against Non-typeable Haemophilus influenzae“. In ERS International Congress 2018 abstracts. European Respiratory Society, 2018. http://dx.doi.org/10.1183/13993003.congress-2018.pa4973.
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Schlyter, Fredrik. „Modulation of attraction by non-host volatiles: Mechanisms for semiochemical diversity“. In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.94021.
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Namkoong, H., Y. Omae, T. Asakura, M. Ishii, S. Suzuki, K. Morimoto, M. Yoshida et al. „Host Genetic Analysis of Pulmonary NTM Disease and Non-CF Bronchietasis“. In American Thoracic Society 2020 International Conference, May 15-20, 2020 - Philadelphia, PA. American Thoracic Society, 2020. http://dx.doi.org/10.1164/ajrccm-conference.2020.201.1_meetingabstracts.a4491.
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Lei, Jin, Yongjun Wang, Xu Zhou und Ke Yan. „BTFuzz: Accurately Fuzzing Bluetooth Host with a Simulated Non-compliant Controller“. In 2022 IEEE 4th International Conference on Civil Aviation Safety and Information Technology (ICCASIT). IEEE, 2022. http://dx.doi.org/10.1109/iccasit55263.2022.9987150.
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Parreu, Isabel, Maria C. Pujol, Magdalena Aguiló, Francesc Díaz, Xavier Mateos und Valentin Petrov. „Lasing of Yb3+ in the non-centrosymmetric host KGd(PO3)4“. In Advanced Solid-State Photonics. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/assp.2007.wb23.
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Tregde, Vidar, und Arne Nestegård. „Prediction of Irregular Motions of Free-Fall Lifeboats During Drops From Damaged FPSO“. In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23090.
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A Free Fall Lifeboat (FFLB) which is evacuating from a damaged host in storm conditions must to be able to safely run away from the host. For a safe evacuation, the FFLB must first of all avoid irregular motion (“log dive”), and secondly resurface at a sufficient distance away from host (headway) to be able to run away. The design standard [1] requires a controlled motion trajectory for the FFLB in waves. A drop simulator for random drops of FFLBs from a floating host in storm conditions, intact or damaged has been developed. Time histories of the host motions are generated and random drops of the FFLBs are done during three hour duration of each sea state. The FFLB point of impact in the wave is identified and the local wave height, wave length and hit point in the wave cycle is found for each of the impact points. A structured database with results from a large number of Computational Fluid Dynamics (CFD) simulations has been made for a specific FFLB. In this CFD screening process the lifeboat has been dropped with variations in wind and waves, as well as varying conditions of host during launch. This database forms the basis for a regression analysis used to estimate responses for each drop of free fall lifeboat found from the drop simulator. The present study proposes a definition and a method to identify irregular motions for FFLBs, and this definition is used as a motion indicator in the regression analysis. By using the proposed motion indicator, the regression analysis provides percentage of acceptable vs. non-acceptable motion trajectories for a given intact or damaged host during a storm condition. The worst conditions are found, and can be used for further analysis of headway, i.e. the ability of the FFLB to escape from the host after resurfacing.
Berichte der Organisationen zum Thema "Host/non-Host"
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Zhao, Bingyu, Saul Burdman, Ronald Walcott und Gregory E. Welbaum. Control of Bacterial Fruit Blotch of Cucurbits Using the Maize Non-Host Disease Resistance Gene Rxo1. United States Department of Agriculture, September 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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Droby, Samir, Tim R. Gottwald, Richard Stange, Efraim Lewinsohn und T. Gregory McCollum. Characterization of the biochemical basis of host specificity of Penicillium digitatum and Penicillium italicum on citrus fruit. United States Department of Agriculture, Mai 2008. http://dx.doi.org/10.32747/2008.7587726.bard.
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l. This research demonstrates that citrus fruit volatiles play an important role in host recognition by P. digitatum and P. italicum. 2. Volatiles derived from non-host fruits and vegetables (apple, pear, tomato, pepper, strawberry and avocado) had no effect on promotion of spore germination and growth of citrus pathogens. 3. Citrus volatiles have a specific stimulatory effect solely on P. digitatum and P. italicum. Non-citrus pathogens such as P. expansum and B. cinerea not affected orinhibited by the volatile materials. The specific stimulatory effect of fruit peelvolatiles on citrus pathogens and inhibitory effect on non-pathogens indicateimport ant role of volatile compounds in the host selectivity of citrus postharvestpathogens. 4. Comparative CG-MS quantification was per formed and identification of volatileconstituents of citrus commercial oils, peel extracts and the headspace of thewounded fruits was completed. Monoterpenehydrocarbons (limonene, a-pinene,sabinene, and myrcene) were the most abundant in all volatiles regardless of thesource. 5. Our results demonstrated stimulation of germination and germ tube growth in both P. digitatum and P. italicum by limonene, myrcene, a-pinene, and b-pinene). Limonenewas show n to be the most efficient in induction of germination and growth in bothpathogens. 6. P. digitatum spores placed on the surface of lemon fruit, adjacent to a wounded oil gland, were induced to germinate and grow, thus supporting all the in vitro results and demonstrating that the phenomenon of stimulation of germination and growth occurs on the fruit. 7. We established that P. digitatum is capable of biotransformation of limonene to a terpineol. a-terpinel was proved to be involved in induction of fungal sporulation process. 8. Chemotropism (directional growth) of P. digitatum towards the volatiles released from the oil glands on fruit surface was demonstrated. 9. Citrus germplasm screening work for fruit susceptibility/resistance for P. digitatum infection showed no definitive results regarding host range and susceptibility.Although the sour orange selections appear to show higher resistance to infection and decay development. 10. We demonstrated that P. expansum, non citrus pathogen, is capable of germinating in citrus fruit surface wounds, but it strongly induced host resistance mechanisms which restrict it growth and prevented decay development. The host (citrus fruit) reacted strongly by production of ROS. On the other hand, P. digitatum seems to actively suppress host natural resistance mechanisms possibly through inhibiting the production of ROS production.
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Grumet, Rebecca, und Benjamin Raccah. Identification of Potyviral Domains Controlling Systemic Infection, Host Range and Aphid Transmission. United States Department of Agriculture, Juli 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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Tzfira, Tzvi, Michael Elbaum und Sharon Wolf. DNA transfer by Agrobacterium: a cooperative interaction of ssDNA, virulence proteins, and plant host factors. United States Department of Agriculture, Dezember 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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Kelly, Luke. Evidence on Measures to Address Security in Camp Settings. Institute of Development Studies, März 2021. http://dx.doi.org/10.19088/k4d.2021.052.
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This rapid literature review finds that authorities use a range of methods to reduce insecurity in camps. Security in camps can be addressed through better planning of services by camp management, by more involvement of refugees, and through the use of outside security support. However, the militarisation of camps is a broader problem that requires political support from a number of stakeholders. The review focuses on insecurity arising from conflict (militarisation) and from crime and disputes within and around camps. It starts from the position that camps for refugees or internally displaced persons (IDPs) should be ‘civilian and humanitarian in character’, and thus, they should not host active combatants or fighters or support conflict. The rights of camp residents - e.g. non-refoulment of refugees - should be respected. In the case of insecurity arising from crime and disputes within and around camps, security measures should be proportionate and consider refugee protection. This review surveys evaluations and academic papers on camp security management. There is a significant body of evidence on the problem of camp militarisation in settings including Zaire/DRC, Thailand, Lebanon and the former Yugoslavia. However, the review has found relatively little evidence on successful efforts to counter militarisation in cases of conflict. It has found case studies and evaluations of a number of programmes to improve lower-level camp security, or in cases where conflict has abated. There are several reviews of UNHCR ’security packages’ involving support to host state police in African countries. These lessons are focused on how to engage with refugee and host populations, as well as host states, and how to manage security services. Guidance on camp management is also surveyed. There is very little evidence discussing liaison arrangements beyond stating the need to provide protection training and oversight for security forces; and the need for principled engagement with states and non-state conflict parties.
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Rodriguez, Russell, und 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, Februar 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, und 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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Aly, Radi, James H. Westwood und Carole L. Cramer. Novel Approach to Parasitic Weed Control Based on Inducible Expression of Cecropin in Transgenic Plants. United States Department of Agriculture, Mai 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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Chejanovsky, Nor, und Suzanne M. Thiem. Isolation of Baculoviruses with Expanded Spectrum of Action against Lepidopteran Pests. United States Department of Agriculture, Dezember 2002. http://dx.doi.org/10.32747/2002.7586457.bard.
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Our long-term goal is to learn to control (expand and restrict) the host range of baculoviruses. In this project our aim was to expand the host range of the prototype baculovirus Autographa cali/arnica nuclear polyhedrosis virus (AcMNPV) towards American and Israeli pests. To achieve this objective we studied AcMNPV infection in the non-permissive hosts L. dispar and s. littoralis (Ld652Y and SL2 cells, respectively) as a model system and the major barriers to viral replication. We isolated recombinant baculoviruses with expanded infectivity towards L. dispar and S. littoralis and tested their infectivity towards other Lepidopteran pests. The restricted host range displayed by baculoviruses constitutes an obstacle to their further implementation in the control of diverse Lepidopteran pests, increasing the development costs. Our work points out that cellular defenses are major role blocks to AcMNPV replication in non- and semi-permissive hosts. Therefore a major determinant ofbaculovirus host range is the ability of the virus to effectively counter cellular defenses of host cells. This is exemplified by our findings showing tliat expressing the viral gene Ldhrf-l overcomes global translation arrest in AcMNPV -infected Ld652Y cells. Our data suggests that Ld652Y cells have two anti-viral defense pathways, because they are subject to global translation arrest when infected with AcMNPV carrying a baculovirus apoptotic suppressor (e.g., wild type AcMNPV carryingp35, or recombinant AcMNPV carrying Opiap, Cpiap. or p49 genes) but apoptose when infected with AcMNPV-Iacking a functional apoptotic suppressor. We have yet to elucidate how hrf-l precludes the translation arrest mechanism(s) in AcMNPV-infected Ld652Y cells. Ribosomal profiles of AcMNPV infected Ld652Y cells suggested that translation initiation is a major control point, but we were unable to rule-out a contribution from a block in translation elongation. Phosphorylation of eIF-2a did not appear to playa role in AcMNPV -induced translation arrest. Mutagenesis studies ofhrf-l suggest that a highly acidic domain plays a role in precluding translation arrest. Our findings indicate that translation arrest may be linked to apoptosis either through common sensors of virus infection or as a consequence of late events in the virus life-cycle that occur only if apoptosis is suppressed. ~ AcMNPV replicates poorly in SL2 cells and induces apoptosis. Our studies in AcMNPV - infected SL2ceils led us to conclude that the steady-state levels of lEI (product of the iel gene, major AcMNPV -transactivator and multifunctional protein) relative to those of the immediate early viral protein lEO, playa critical role in regulating the viral infection. By increasing the IEl\IEO ratio we achieved AcMNPV replication in S. littoralis and we were able to isolate recombinant AcMNPV s that replicated efficiently in S. lifforalis cells and larvae. Our data that indicated that AcMNPV - infection may be regulated by an interaction between IE 1 and lED (of previously unknown function). Indeed, we showed that IE 1 associates with lED by using protein "pull down" and immunoprecipitation approaches High steady state levels of "functional" IE 1 resulted in increased expression of the apoptosis suppressor p35 facilitating AcMNPV -replication in SL2 cells. Finally, we determined that lED accelerates the viral infection in AcMNPV -permissive cells. Our results show that expressing viral genes that are able to overcome the insect-pest defense system enable to expand baculovirus host range. Scientifically, this project highlights the need to further study the anti-viral defenses of invertebrates not only to maximi~e the possibilities for manipulating baculovirus genomes, but to better understand the evolutionary underpinnings of the immune systems of vertebrates towards virus infection.
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Burdman, S., E. Welbaum, R. Walcott und B. Zhao. erial fruit blotch, elucidating the mechanisms of fruit infection by Acidovorax citrulli. Israel: United States-Israel Binational Agricultural Research and Development Fund, 2020. http://dx.doi.org/10.32747/2020.8134162.bard.
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Bacterial fruit blotch (BFB) of cucurbits is caused by the Gram-negative bacterium Acidovorax citrulli. BFB affects cucurbit production worldwide, and mainly watermelon and melon. Most A. citrulli strains are divided into two genetically differentiated groups: while group I strains have been mainly associated with melon and other non-watermelon cucurbits, group II strains are more aggressive on watermelon. Like many Gram-negative plant-pathogenic bacteria, A. citrulli relies on a functional type III secretion system (T3SS) for pathogenicity. The T3SS is responsible for direct secretion of bacterial protein effectors to the host cell. Type III-secreted effectors (T3Es) contribute to virulence through manipulation of the host cell metabolism and suppression of plant defense. Our previous collaboration showed that group I and II strains significantly differ in their T3E arsenal (Eckshtain-Levi et al., Phytopathology 2014, 104:1152-1162). Using comparative genomics, we also showed that group I and II strains of A. citrulli have substantial differences in their genome content (Eckshtain-Levi et al., Front. Microbiol. 2016, 7:430). Our long-term goals are to identify the genetic determinants that contribute to virulence and host preferential association of the two major groups of A. citrulli, and to exploit these insights to develop effective BFB management strategies. We hypothesize that differences in the arsenal of T3Es, are greatly responsible for the differences in host preferential association between strains belonging to the two groups. The specific objectives of this project were: (1) to investigate the susceptibility of cucurbit species to group I and II strains under field conditions; (2) to assess the contribution of T3Es and other virulence factors to A. citrulli virulence and host preference; and (3) to characterize the mechanisms of action of selected T3Es of A. citrulli. In the frame of objective 1, we carried out three field experiments involving inoculation of several cucurbit crops (watermelon, melon, pumpkin and squash) with group I and II strains. Findings from these experiments confirmed that A. citrulli strains exhibit a preference for watermelon and melon. Moreover, we demonstrated, for the first time under field conditions, host-preferential association of group I and II strains to melon and watermelon, respectively. While host-preferential association was observed in leaves and in fruit tissues, it was more pronounced in the latter. In this part of the project we also developed a duplex PCR assay to differentiate between group I and II strains. In the frame of objective 2, we employed a multifaceted approach combining bioinformatics and experimental methods to elucidate the T3E arsenal of A. citrulli. These experiments led to discovery that A. citrulli strains possess large arsenals with more than 60 T3E genes. Remarkably, we found that ~15% of the T3E genes are group-specific. Advances were achieved on the contribution of selected T3E genes and other virulence determinants to the ability of A. citrulli to colonize the fruit and other tissues of melon and watermelon. Last, in the frame of objective 3, we advanced our understanding on the mode of action of few key T3Es of A. citrulli. We also optimized a virus-induced gene silencing (VIGS) system for functional genomics in melon and watermelon. This system will allow us to test melon and watermelon genes that may have defense or susceptibility roles related to BFB disease. Overall, this collaboration substantially enriched our knowledge on basic aspects of BFB disease. We believe that the fruits of this collaboration will greatly contribute to our ultimate goal, which is generation of durable resistance of melon and watermelon to A. citrulli.