Literatura académica sobre el tema "Plant immunty"
Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros
Consulte las listas temáticas de artículos, libros, tesis, actas de conferencias y otras fuentes académicas sobre el tema "Plant immunty".
Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.
También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.
Artículos de revistas sobre el tema "Plant immunty"
1
Hou, Shuguo, Yifei Yang, Daoji Wu y Chao Zhang. "Plant immunity". Plant Signaling & Behavior 6, n.º 6 (junio de 2011): 794–99. http://dx.doi.org/10.4161/psb.6.6.15143.
Texto completo
2
Lewis, Jennifer D. "Plant immunity". Seminars in Cell & Developmental Biology 56 (agosto de 2016): 122–23. http://dx.doi.org/10.1016/j.semcdb.2016.07.003.
Texto completo
3
Nobori, Tatsuya, André C. Velásquez, Jingni Wu, Brian H. Kvitko, James M. Kremer, Yiming Wang, Sheng Yang He y Kenichi Tsuda. "Transcriptome landscape of a bacterial pathogen under plant immunity". Proceedings of the National Academy of Sciences 115, n.º 13 (12 de marzo de 2018): E3055—E3064. http://dx.doi.org/10.1073/pnas.1800529115.
Texto completoResumen
Plant pathogens can cause serious diseases that impact global agriculture. The plant innate immunity, when fully activated, can halt pathogen growth in plants. Despite extensive studies into the molecular and genetic bases of plant immunity against pathogens, the influence of plant immunity in global pathogen metabolism to restrict pathogen growth is poorly understood. Here, we developed RNA sequencing pipelines for analyzing bacterial transcriptomes in planta and determined high-resolution transcriptome patterns of the foliar bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana with a total of 27 combinations of plant immunity mutants and bacterial strains. Bacterial transcriptomes were analyzed at 6 h post infection to capture early effects of plant immunity on bacterial processes and to avoid secondary effects caused by different bacterial population densities in planta. We identified specific “immune-responsive” bacterial genes and processes, including those that are activated in susceptible plants and suppressed by plant immune activation. Expression patterns of immune-responsive bacterial genes at the early time point were tightly linked to later bacterial growth levels in different host genotypes. Moreover, we found that a bacterial iron acquisition pathway is commonly suppressed by multiple plant immune-signaling pathways. Overexpression of a P. syringae sigma factor gene involved in iron regulation and other processes partially countered bacterial growth restriction during the plant immune response triggered by AvrRpt2. Collectively, this study defines the effects of plant immunity on the transcriptome of a bacterial pathogen and sheds light on the enigmatic mechanisms of bacterial growth inhibition during the plant immune response.
4
Maksimov, I. V. y R. M. Khairullin. "Plant immunity and plant microbiome". Agrarian science 327, n.º 2 (2019): 40–44. http://dx.doi.org/10.32634/0869-8155-2019-326-2-40-44.
Texto completo
5
Pruitt, Rory N., Andrea A. Gust y Thorsten Nürnberger. "Plant immunity unified". Nature Plants 7, n.º 4 (30 de marzo de 2021): 382–83. http://dx.doi.org/10.1038/s41477-021-00903-3.
Texto completo
6
Ngou, Bruno Pok Man, Pingtao Ding y Jonathan D. G. Jones. "Channeling plant immunity". Cell 184, n.º 13 (junio de 2021): 3358–60. http://dx.doi.org/10.1016/j.cell.2021.05.035.
Texto completo
7
Jamison, Judy. "Boosting plant immunity". Nature Biotechnology 18, n.º 7 (julio de 2000): 703. http://dx.doi.org/10.1038/77240.
Texto completo
8
Jung, Su-Jin, Hong Gil Lee y Pil Joon Seo. "Membrane-triggered plant immunity". Plant Signaling & Behavior 9, n.º 9 (16 de julio de 2014): e29729. http://dx.doi.org/10.4161/psb.29729.
Texto completo
9
Mengiste, Tesfaye. "Plant Immunity to Necrotrophs". Annual Review of Phytopathology 50, n.º 1 (8 de septiembre de 2012): 267–94. http://dx.doi.org/10.1146/annurev-phyto-081211-172955.
Texto completo
10
Alderton, Gemma. "Networks in plant immunity". Science 360, n.º 6395 (21 de junio de 2018): 1310.12–1312. http://dx.doi.org/10.1126/science.360.6395.1310-l.
Texto completoTesis sobre el tema "Plant immunty"
1
Cheng, Yu Ti. "Dissecting plant innate immunity using SNC1 : a sensitive immune receptor". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44310.
Texto completo
2
Steele, John. "Molecular recognition in plant immunity". Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/58564/.
Texto completoResumen
Plant pathogens constitute a major threat to global food security. The use of naturally resistant crop varieties can limit crop losses, however new races of pathogen can arise that are able to overcome these defences. Plant breeding for race-specific resistance typically relies on disease-resistance genes, which generally encode proteins with nucleotide-binding and leucine-rich repeat domains (NB-LRRs). NB-LRRs are a large of proteins found in both plants and animals, with plant NB-LRRs further classified by the presence of N-terminal coiled-coil or toll-interleukin receptor domains. Although qualitative models exist to describe R-protein regulation and activation, these are predominantly based on genetic and molecular studies. Biochemical investigations into R-protein function have been hampered by difficulties obtaining sufficient yields of material. When suitable material has been identified, biochemical studies have been used to complement well-established in planta assays to validate numerous hypotheses. This work describes the screening processes undertaken to obtain R-protein domains suitable for downstream experiments. Using E. coli for high-throughput screening of constructs from a single R-protein, traditional construct design to investigate multiple R-protein domains and expanding our expression hosts to eukaryotic systems we successfully purified four coiled-coil domains and a single NBARC domain for use in downstream experiments. Characterisation of this NBARC domain by circular dichroism and small-angle X-ray scattering indicates that the protein is well-folded and stable in solution, allowing in vitro investigations. In testing models for R-protein regulation we were able to confirm previous findings, such as low levels of ATPase activity, however we were unable to find evidence for a commonly cited method of signal repression. A preliminary crystal structure of the NBARC domain shows significant similarity to Apaf-1, and highlights the importance of conserved motifs in NBARC architecture. The tools presented here should prove a valuable resource to complement existing models to better understand the structure, biochemistry, and ultimately regulation of plant R-proteins.
3
Gao, Qing-Ming. "GLYCEROLIPIDS AND THE PLANT CUTICLE CONTRIBUTE TO PLANT IMMUNITY". UKnowledge, 2012. http://uknowledge.uky.edu/plantpath_etds/4.
Texto completoResumen
The conserved metabolites, oleic acid (18:1), a major monounsaturated fatty acid (FA), and glycerol-3-phosphate (G3P) are obligatory precursors of glycerolipid biosynthesis in plants. In Arabidopsis, the SSI2-encoded SACPD is the major isoform that contributes to 18:1 biosynthesis. Signaling induced upon reduction in oleic acid (18:1) levels not only upregulates salicylic acid (SA)-mediated responses but also inhibits jasmonic acid (JA)- inducible defenses. I examined the transcription profile of ssi2 plants and identified two transcription factors, WRKY50 and WRKY51. Although the ssi2 wrky50 and ssi2 wrky51 plants were constitutively upregulated in SA-derived signaling, they were restored in JAdependent defense signaling. Not only did these plants show JA-inducible PDF1.2 expression, but they were also restored for basal resistance to the necrotrophic pathogen, Botrytis cinerea. Overall, my results show that the WRKY50 and WRKY51 proteins mediate both SA- and low 18:1-dependent repression of JA signaling in Arabidopsis plants.
My studies also show that cellular G3P levels are important for plant defense to necrotrophic pathogens. I showed that G3P levels are induced in Arabidopsis in response to the necrotrophic fungal pathogen B. cinerea. G3P-dependant induction of basal defense is not via the activities of other defense-related hormones such as SA, JA or the phytoalexin camalexin. Arabidopsis mutants unable to accumulate G3P (gly1, gli1) showed enhanced susceptibility to B. cinerea.
Previous studies in our lab identified acyl-carrier protein 4 (ACP4), a component of FA and lipid biosynthesis, as an important regulator of plant systemic immunity. ACP4 mutant plants were defective in systemic acquired resistance (SAR) because they contained a defective cuticle. I further investigated the role of the plant cuticle in SAR by studying the involvement of long-chain acyl-CoA synthetases (LACS), a gene family involved in long-chain FA and cuticle biosynthesis, in SAR. In all, eight lacs mutants (lacs1, lacs2, lacs3, lacs4, lacs6, lacs7, lacs8, lacs9) were isolated and characterized. Six mutants were compromised in SAR. Together, my studies show that the various LACS isoforms contribute differentially to both cuticle formation and systemic immunity in Arabidopsis.
4
Scandolera, Tiffanie. "Interactions plante-virus : impacts d'un fort taux de CO2 atmosphérique et de fortes températures sur la résistance/sensibilité des plantes aux virus dans le contexte du changement climatique". Electronic Thesis or Diss., université Paris-Saclay, 2025. http://www.theses.fr/2025UPASB014.
Texto completoResumen
Comprendre et anticiper l’impact du changement climatique sur les interactions plantes-bioagresseurs est un enjeu majeur pour l’agriculture de demain. Les modèles de prédiction climatiques prévoient une hausse de la concentration en CO₂ atmosphérique qui pourrait passer de 400 µl.L-1 en 2014, à 1000 µL.L-1 en 2100 ainsi qu’une élévation de la température moyenne annuelle de 4.6°C d’ici 2100. Les plantes sont directement impactées par la hausse du taux de CO₂ atmosphérique et de la température.L’objectif de ce projet de thèse est d’étudier l’impact d’un fort CO₂ et de températures élevées sur le niveau de résistance/sensibilité aux virus des plantes. Le modèle d’étude est le haricot commun (Phaseolus vulgaris L.), une plante d’intérêt agronomique, en réponse à l’infection par un comovirus, le bean pod mottle virus (BPMV, Comovirus siliquae). Deux génotypes de haricot commun ont été étudiés dans le cadre de ce projet: un génotype naturellement résistant au BPMV (BAT93), et un génotype naturellement sensible (Black Valentine).Cette étude est décomposée en trois parties: dans un premier temps, une approche par sélection a priori de gènes impliqués dans différentes voies de défenses aux virus a été choisie pour étudier 1/ l’impact d’un fort CO₂ et 2/ l’impact de températures élevées sous forme de vagues de chaleur sur la résistance/sensibilité au BPMV chez les deux génotypes de P. vulgaris Dans un deuxième temps, une étude plus exhaustive par RNAseq a été réalisée afin d’étudier 3/ l’effet combiné de fort CO₂ et vague de chaleur sur la résistance au BPMV chez le génotype naturellement résistant de P. vulgaris, BAT93Understanding and anticipating the impact of climate change on plant-pathogen interactions is a major challenge for the agriculture of tomorrow. Climate predictive models forecast an increase in atmospheric CO₂ concentration from 400 µL.L-1 in 2014 to 1000 µL.L-1 by 2100, as well as a rise in the average annual temperature of 4.6°C by 2100. Plants are directly affected by the increase in CO₂ levels and temperature. The objective of this doctoral project is to study the impact of high CO₂ and elevated temperatures on the level of plant resistance/susceptibility to viruses. The model organism is the common bean (Phaseolus vulgaris L.), an agronomically significant plant, in response to infection by a comovirus, the bean pod mottle virus (BPMV, Comovirus siliquae).Two common bean genotypes were studied in this project: one that is naturally resistant to BPMV (BAT93) and one that is naturally susceptible (Black Valentine).This study is divided into three parts. First, an approach based on the a priori selection of genes involved in different defense pathways against viruses was chosen to study 1/ the impact of high CO₂ and 2/ the impact of heat waves on resistance/susceptibility to BPMV in in both genotypes of P. vulgaris.Second, a more comprehensive approach was performed by RNAseq, in order to study 3/ the combined effect of high CO₂ and heat waves on resistance to BPMV in the naturally resistant genotype of P. vulgaris, BAT93
5
Prince, David. "Dissecting the role of plant immunity in plant-aphid interactions". Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/42420/.
Texto completoResumen
Aphids are economically important phloem-feeding insects that cause loss in plant productivity worldwide. This occurs through the removal of photoassimilates and the vectoring of hundreds of plant viruses. Plants possess a complex immune system in order to defend themselves from a range of pathogens including bacteria and fungi. I aimed to discover if this immune system was also involved in defence against aphids. I found that aphids have proteins that trigger plant immune responses. The aphid Myzus persicae contains several protein elicitors with varying molecular weights. These proteins are perceived by the plants Nicotiana benthamiana and Arabidopsis thaliana. In A. thaliana the perception of a 3 to 10 kDa elicitor fraction requires the leucine-rich repeat receptor-like kinase (LRR-RLK) BAK1, as a mutant in this gene was deficient in immune responses activated by this elicitor. Plant recognition of the elicitor is unlikely to depend on a single non-arginine-asparate (non-RD) RLK. In addition, aphids possess the means to modulate the plant immune response. I helped to identify three aphid effectors that modulate plant processes. I then investigated the role of one of these effectors, a M. persicae chemosensory protein (CSP) known as Mp10, in suppressing the immune responses triggered by the aphid elicitors. Mp10 is likely to disrupt the function of plant genes near the top of the immune signalling cascade in N. benthamiana in order to suppress elicitor-triggered immunity. Surprisingly, the homologs of this CSP in other aphids also show the same ability to suppress plant immune responses, suggesting an important role for Mp10 in plant-aphid interactions. This is the first report of a role for elicitor recognition by plants in aphid defence, the use of plant cell surface receptors to detect insects, and aphids’ attempts to suppress plant immunity.
6
Goritschnig, Sandra. "Protein modification in plant innate immunity". Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/30887.
Texto completoResumen
Plant diseases cause major crop losses worldwide. Crop protection
strategies enhancing the plants' own defence mechanisms could be a sustainable
solution to ensure future food supply. This thesis describes my research effort to
better understand the innate defence mechanisms in plants.
Specific resistance responses towards invading pathogens are mediated by
Resistance (R) proteins. They recognize pathogen-derived molecules and activate
signalling cascades, initiating physiological responses to limit pathogen spread in
infected cells while minimizing harmful effects on the rest of the plant.
We use the unique gain-of-function R gene snd as a tool to identify
components of resistance signalling in Arabidopsis thaliana. In a screen for
suppressors of snc7-mediated constitutive resistance, we identified a number of
modifier of snd (mos) mutants. My thesis focuses on the identification and
characterization of mos5 and mos8. Both mutations partially suppress sndassociated
morphological phenotypes and revert susceptibility to virulent
pathogens to wild type levels.
mos5 contains a deletion in one of two ubiquitin activating enzyme genes in
Arabidopsis. The mutation in mos5 lies in a putative binding domain, potentially
disrupting interaction with downstream ubiquitin acceptors. The mos5 single
mutant displays enhanced susceptibility to virulent bacteria, as well as to bacteria
carrying the effector protease AvrRpt2, indicating a role of ubiquitination in both
specific and basal resistance. A mutation in the mos5 homolog UBA2 does not
affect resistance, however, a double mutant mos5 uba2 is lethal, indicating that the
two genes are partially redundant.
mos8 is allelic to enhanced response to abscisic acid 1 (eral), which
encodes the beta subunit of protein farnesyltransferase. Mutations in the gene are
known to affect development and abscisic acid signalling. mos8 displays enhanced
susceptibility to virulent and avirulent pathogens and acts additively with NPR1.
Defects in geranylgeranylation, a protein modification similar to farnesylation, do
not affect resistance responses against virulent or avirulent pathogens. Taken together, my data reveals the importance of post-translational
modification of yet to be identified regulatory proteins in plant innate immunity.
Further research will aim at unravelling the mechanisms by which mos5 and mos8
affect resistance signalling.Science, Faculty of
Botany, Department of
Graduate
7
Truman, William Matthew Donald. "Signalling pathways underylying plant innate immunity". Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429264.
Texto completo
8
Escouboué, Maxime. "La phosphorylation de l'effecteur PopP2 de Ralstonia solanacearum par des MAPKs immunitaires potentialise ses fonctions de virulence et limite sa reconnaissance chez Arabidopsis". Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30041.
Texto completoResumen
Les bactéries phytopathogènes injectent des facteurs de virulence (appelés effecteurs) dans leurs cellules hôtes pour interférer avec de nombreuses voies de signalisation immunitaires. La bactérie Gram négative Ralstonia solanacearum est l'agent causal du flétrissement bactérien. Parmi ses nombreux effecteurs de type III figure PopP2 dont les fonctions de virulence et d'avirulence ont été largement étudiées précédemment. PopP2 cible les facteurs de transcription de défense WRKY et les acétyles pour inhiber la résistance basale (PTI). Au cours de ce travail, nous montrons que la phosphorylation de PopP2 in planta au niveau de trois motifs SP nécessite la présence d'un domaine de type " MAPK-docking domain " situé dans son extrémité N-terminale. Bien que la phosphorylation de PopP2 n'affecte pas sa reconnaissance chez Arabidopsis par le complexe d'immuno-récepteurs RPS4/RRS1-R, ses fonctions de virulence dépendent strictement de cette modification. De façon surprenante, les phosphomutants PopP2, incapables d'être phosphorylés in planta, ont un comportement de protéine avirulente chez un grand nombre d'accessions, indépendamment de la paire RPS4/RRS1-R. Par le biais de différentes approches biochimiques et de microscopie confocale, nous montrons que PopP2 est un substrat de différentes MAPKs associées à la réponse immunitaire et notamment d'AtMPK3 avec qui l'effecteur interagit physiquement au sein du noyau. De façon intéressante, l'activation des activités des MAPKs au cours de la PTI coïncide avec la stimulation du niveau de phosphorylation du PopP2. Une analyse RNA-seq indique que la phosphorylation de PopP2 participe à la dérégulation de nombreux gènes liés aux réponses de défense. Des hypothèses concernant la façon dont le niveau de phosphorylation de PopP2 modulerait ses activités in planta sont présentées. Globalement, ce travail révèle une stratégie de virulence utilisée par un effecteur bactérien qui exploite les MAPKs associées à l'immunité pour (i) potentialiser ses fonctions de virulence et (ii) limiter sa détection chez l'hôteMicrobial pathogens infect host cells by delivering virulence factors (effectors) that interfere with defense. The Gram-negative Ralstonia solanacearum is the causal agent of bacterial wilt. The well-characterized PopP2 effector form R. solanacearum binds to and acetylate WRKY defensive transcription factors to dampen basal defense responses. In this work, we show that PopP2 phosphorylation on three SP motifs involves a MAPK-docking like domain located in its N-terminus. Although PopP2 phosphorylation does not affect its avirulence activity in Arabidopsis expressing the RPS4/RRS1-R immune receptor complex, its virulence functions strictly depend on this modification. Through different biochemical and confocal microscopy approaches, we show that PopP2 is a substrate of different MAPKs associated with the immune response and in particular, AtMPK3 with which the effector physically interacts in the plant nucleus. Interestingly, activation of MAPK activities during establishment of PTI coincides with the stimulation of the phosphorylation level of PopP2. An RNA-seq analysis indicates that the phosphorylation of PopP2 contributes to the deregulation of many genes related to defense responses. Hypotheses about how PopP2's phosphorylation level would modulate its activities in planta are presented. Overall, this work reveals a virulence strategy used by a bacterial effector that exploits MAPKs associated with immunity to (i) potentiate its virulence functions and (ii) limit its detection in the host
9
Case, Olivia Hildegard. "An assessment of medicinal hemp plant extracts as natural antibiotic and immune modulation phytotherapies". Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&.
Texto completoResumen
This study aimed to evaluate the antimicrobial efficacy of medicinal hemp plant extracts to determine the antibacterial effects of indigenous Sansevieria species and exotic Cannabis sativa phytotherapy varieties. This study also assessed whether aqueous o
10
Camargo, Ramírez Rosany del Carmen. "Function of microRNAs in plant innate immunity". Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/405716.
Texto completoResumen
Esta tesis aborda el estudio de miARNs en la inmunidad innata en plantas. El trabajo se ha desarrollado en arroz (Capítulo I y Capítulo II) y en Arabidopsis (Capítulo III), En el capítulo I se describe la identificación y caracterización funcional de nuevos miARNs de arroz en su interacción con el hongo Magnaporthe oryzae. Este hongo es responsable de la piriculariosis, una de las enfermedades más devastadoras para el cultivo del arroz a nivel mundial. A partir de la información generada mediante secuenciación masiva de bibliotecas de pequeños ARNs de arroz, se seleccionaron secuencias candidatas a representar nuevos miARNs de arroz, habiéndose estudiado 5 de estos candidatos (miR-64, miR-75, miR-96, miR-98 y miR-203). La obtención de líneas transgénicas de arroz ha permitido demostrar que la sobreexpresión de MIR-64 y MIR-75 confiere resistencia a M. oryzae, tratándose por lo tanto de miARNs que funcionan como reguladores positivos en la respuesta inmune de arroz. Por otra parte, la sobreexpresión de MIR-96, MIR-98 o MIR-203 aumenta la susceptibilidad a la infección por M. oryzae en plantas de arroz (reguladores negativos de la respuesta inmune). El análisis de mutantes de arroz afectados en la biogénesis de miARNs (mutantes dcl1, dcl3 y dcl4) indican que la producción del miARN maduro miR-64, miR-75 o miR-96 es dependiente de DCL3 y/o DCL4, lo cual apoya la idea de que se trata de nuevos miARNs de arroz. Además, mediante edición génica por CRISPR/Cas9, se ha comprobado que una delección de 22 nucleótidos en el precursor miR-75 resulta en un fenotipo de susceptibilidad a M. oryzae (Capítulo II), lo que concuerda con el fenotipo de resistencia que se observa en las plantas que sobreexpresan este miARN.
En el capítulo III se ha estudiado la función de miR858 en la inmunidad innata de Arabidopsis thaliana frente a la infección por hongos patógenos. Este miARN reprime la expresión de factores de transcripción de tipo MYB que actúan como activadores de la expresión de genes que participan en la biosíntesis de flavonoides. Cuando la actividad del miR858 se encuentra bloqueada por la expresión de un gen de imitación de díana (plantas MIM858), las plantas son resistentes a la infección por hongos patógenos (Plectosphaerella cucumerina, Fusarium oxysporum f. sp. Conglutinans and Colletotrichum higginsianum), mientras que la sobreexpresión de este miARN confiere mayor susceptibilidad a la infección. Además, la interferencia con la actividad de miR858, y consiguiente aumento de la expresión de genes MYB, en las plantas MIM858 afecta de manera importante el metabolismo de fenilpropanoides, priorizándose la síntesis y acumulación de flavonoides, a expensas de la síntesis de precursores de lignina. La actividad antifúngica que se observa para kaempferol, naringenina (flavonoides) y ácido p-cumárico, explicaría el fenotipo de resistencia a la infección por hongos que se observa en las plantas MIM858.
En su conjunto, los resultados obtenidos en este trabajo demuestran que los miARNs son componentes importantes en la resistencia/susceptibilidad a la infección por patógenos fúngicos en plantas de arroz y Arabidopsis. Un mayor conocimiento de función de miARNs en la inmunidad innata de las plantas, y de los procesos que son regulados por estos riboreguladores, puede ser de utilidad en el diseño de nuevas estrategias para el control de enfermedades en plantas.This thesis comprises the study of miRNAs in innate immunity in plants. The work has been developed in rice (Chapter I and Chapter II) and in Arabidopsis (Chapter III), model systems used in studies of functional genomics in monocotyledonous and dicotyledonous species, respectively. Chapter I describes the functional identification and characterization of new rice miRNAs in their interaction with the fungus Magnaporthe oryzae. This fungus is responsible for blast disease, one of the most devastating diseases for rice cultivation worldwide. From the information generated by high-throughput sequencing of small rice RNA libraries, candidate sequences to represent novel rice miRNAs were selected. In this work 5 of these candidates have been studied (miR-64, miR-75, miR-96, miR-98 and miR-203). Obtaining transgenic rice lines has demonstrated that the overexpression of MIR-64 and MIR-75 confers resistance to M. oryzae, therefore these miRNAs function as positive regulators in the rice immune response. Moreover, overexpression of MIR-96, MIR-98 or MIR-203 increase susceptibility to M. oryzae in rice plants (negative regulators of immune response). Analysis of rice mutants affected in the miRNA biogenesis (dcl1, dcl3 and dcl4 mutants) indicate that the mature miRNA production of miR-64, miR-75 or miR-96 depends on DCL3 and/or DCL4, which supports the idea that they are novel rice miRNAs. Furthermore, by gene editing using CRISPR/Cas9, it has been found that a 22 nucleotides deletion in miR-75 precursor results in a susceptibility phenotype under M. oryzae infection (Chapter II), in agreement with a resistance phenotype that was observed in overexpressor plants for this miRNA. In chapter III, the miR858 function in Arabidopsis thaliana innate immunity to infection by pathogenic fungi was studied. This miRNA represses the expression of MYB transcription factors, which act as activators of the expression of genes involved in flavonoids biosynthesis. Plants are resistant to infection by pathogenic fungi (Plectosphaerella cucumerina, Fusarium oxysporum f. sp. Conglutinans and Colletotrichum higginsianum) when the activity of miR858 is blocked by the expression of target mimicry (MIM858 plants), while the overexpression of this miRNA confers greater susceptibility to infection. Additionally, interference with miR858 activity and consequent increase of MYB gene expression in MIM858 plants significantly affects phenylpropanoids metabolism, favoring the synthesis and accumulation of flavonoids, and disfavoring the synthesis of lignin precursors. The antifungal activity that was observed for Kaempferol, naringenin (flavonoids) and p-Coumaric acid, would explain the resistant phenotype by fungi infection which is observed in the MIM858 plants. Altogether, the results obtained in this work demonstrate that miRNAs are an important component in the resistance/susceptibility to infection by pathogenic fungi in Arabidopsis and rice plants. Greater knowledge of miRNA function in plant innate immunity and processes that are regulate by these riboregulators, can be useful in the design of new strategies for the control of diseases in plants.
Libros sobre el tema "Plant immunty"
1
McDowell, John M., ed. Plant Immunity. Totowa, NJ: Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61737-998-7.
Texto completo
2
Sessa, Guido, ed. Molecular Plant Immunity. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118481431.
Texto completo
3
Gassmann, Walter, ed. Plant Innate Immunity. New York, NY: Springer New York, 2019. http://dx.doi.org/10.1007/978-1-4939-9458-8.
Texto completo
4
Sessa, Guido. Molecular plant immunity. Chichester, West Sussex: Wiley-Blackwell, 2013.
Buscar texto completo
5
Loon, L. C. van. Plant innate immunity. Editado por Wiley online library. Amsterdam: Elsevier Academic Press, 2009.
Buscar texto completo
6
Vidhyasekaran, P. Plant Hormone Signaling Systems in Plant Innate Immunity. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-017-9285-1.
Texto completo
7
Vidhyasekaran, P. PAMP Signals in Plant Innate Immunity. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-007-7426-1.
Texto completo
8
Vidhyasekaran, P. Switching on Plant Innate Immunity Signaling Systems. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-26118-8.
Texto completo
9
Vidhyasekaran, P. Plant Innate Immunity Signals and Signaling Systems. Dordrecht: Springer Netherlands, 2020. http://dx.doi.org/10.1007/978-94-024-1940-5.
Texto completo
10
Mishra, Manoj Kumar y Nishi Kumari, eds. Plants for Immunity and Conservation Strategies. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2824-8.
Texto completoCapítulos de libros sobre el tema "Plant immunty"
1
Ellis, Jeffrey G. y David A. Jones. "Plant Disease Resistance Genes". En Innate Immunity, 27–45. Totowa, NJ: Humana Press, 2003. https://doi.org/10.1007/978-1-59259-320-0_2.
Texto completo
2
Monaghan, Jacqueline, Tabea Weihmann y Xin Li. "Plant Innate Immunity". En Plant-Environment Interactions, 119–36. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89230-4_7.
Texto completo
3
Park, Chang Jin y Pamela C. Ronald. "The Rice Xa21 Immune Receptor Recognizes a Novel Bacterial Quorum Sensing Factor". En Molecular Plant Immunity, 1–21. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118481431.ch1.
Texto completo
4
Ökmen, Bilal y Pierre J. G. M. de Wit. "Cladosporium fulvum-Tomato Pathosystem: Fungal Infection Strategy and Plant Responses". En Molecular Plant Immunity, 211–24. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118481431.ch10.
Texto completo
5
Westwood, Jack H. y John P. Carr. "Cucumber Mosaic Virus-ArabidopsisInteraction: Interplay of Virulence Strategies and Plant Responses". En Molecular Plant Immunity, 225–50. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118481431.ch11.
Texto completo
6
Chen, Yan-Jun, Michael F. Lyngkjaer y David B. Collinge. "Future Prospects for Genetically Engineering Disease-Resistant Plants". En Molecular Plant Immunity, 251–75. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118481431.ch12.
Texto completo
7
Ma, Lisong, Harrold A. van den Burg, Ben J. C. Cornelissen y Frank L. W. Takken. "Molecular Basis of Effector Recognition by Plant NB-LRR Proteins". En Molecular Plant Immunity, 23–40. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118481431.ch2.
Texto completo
8
Coaker, Gitta y Douglas Baker. "Signal Transduction Pathways Activated by R Proteins". En Molecular Plant Immunity, 41–53. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118481431.ch3.
Texto completo
9
Kachroo, Pradeep y Aardra Kachroo. "The Roles of Salicylic Acid and Jasmonic Acid in Plant Immunity". En Molecular Plant Immunity, 55–79. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118481431.ch4.
Texto completo
10
Feng, Feng y Jian-Min Zhou. "Effectors of Bacterial Pathogens: Modes of Action and Plant Targets". En Molecular Plant Immunity, 81–106. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118481431.ch5.
Texto completoActas de conferencias sobre el tema "Plant immunty"
1
Lee, Junho, Tae Hong Kim, Hyungsoo Kim, Woonghwan Ryu, Jae Chun Choi y Joungho Kim. "Design Comparison of I/O Port Ground and Power Plane for Enhanced ESD Immunity". En 1992 International Symposium on Electromagnetic Compatibility, 799–803. IEEE, 1992. https://doi.org/10.1109/isemc.2002.10792207.
Texto completo
2
Lee, Junho, Tae Hong Kim, Hyungsoo Kim, Woonghwan Ryu, Jae Chun Choi y Joungho Kim. "Design Comparison of I/O Port Ground and Power Plane for Enhanced ESD Immunity". En 2002_EMC-Europe_Sorrento, 799–803. IEEE, 2002. https://doi.org/10.23919/emc.2002.10879962.
Texto completo
3
Holland, M. L. "Practical Experience with Countering Metal Dusting in a Methane Reforming Unit". En CORROSION 2001, 1–14. NACE International, 2001. https://doi.org/10.5006/c2001-01385.
Texto completoResumen
Abstract Metal dusting problems experienced around one of the world’s largest oxygen-blown secondary methane reformers in a gas-to-liquids synthetic fuel plant are reviewed. Practical plant exposure trials of various materials were conducted in the reformer inlet area, the waste heat boiler tubesheet in the gas inlet chamber, and the waste heat boiler by-pass valve in the gas outlet chamber. Alloy UNS N08810 was found to greatly out-perform the high nickel alloy UNS N06600 in the reformer gas inlet stream but was found to be extremely vulnerable to metal dusting attack in the reformer gas outlet stream. Improved performance was experienced in the by-pass valve with 310 stainless steel which had been treated by a proprietary process to diffuse aluminium into the surface, but the most resistant materials were found to be alloy UNS N06601 and 50/50 Cr-Ni. The latter material appeared to be immune to metal dusting attack after 17 months exposure. The waste heat boiler inlet tubesheet was also successfully protected from metal dusting attack by a thermal spray coating of 50/50 Cr-Ni. The high velocity oxy-fuel (HVOF) application process was found to achieve superior coating integrity to the arc spray process.
4
Paul, Larry. "Weld Overlay Materials for Extending the Life of Boiler Tubes in Coal Fired Power Plants". En CORROSION 2008, 1–17. NACE International, 2008. https://doi.org/10.5006/c2008-08442.
Texto completoResumen
Abstract The use of corrosion resistant weld overlay materials has proven to be a very effective method to extend the life of boiler tubes in coal fired boilers. In order to properly select the best material to use for a weld overlay, the corrosive conditions need to be understood in the various regions of the boiler. The cost of the protection method and ease of application also need to be considered when selecting an overlay material. In the furnace region where combustion occurs, the water-wall tubes are exposed to high heat inputs along with corrosive combustion gases and deposits. These conditions can cause rapid corrosion by a mixed sulfidation/oxidation mechanism. The corrosion rates increase if low NOx combustion practices are used, since this causes a reducing atmosphere that forms more corrosive sulfur species such as H2S gases and FeS deposits. The corrosion rates increase with tube metal temperatures, which are controlled by pressure of the water used to cool the boiler tubes. In the highest pressure units that operate above the water triple point (supercritical plants), cracking is also an issue. This cracking is caused by a corrosion fatigue mechanism and is generally referred to as “circumferential cracking” in the industry. In the case of waterwall corrosion, it has been found that higher chromium materials best resist the corrosion conditions. The main materials currently used to overlay waterwall tubes are Type 309 stainless steel (23Cr-13Ni-58Fe), Alloy 22 (22Cr-57Ni-13Mo-3W) and Alloy 33 (33Cr-32Fe-31Ni). This last material has the highest chromium content and is therefore the most corrosion resistant. Overlay material selection for supercritical units is further complicated by the possibility of cracking. While not yet fully understood, it is generally agreed that certain material properties improve resistance to cracking; these include the materials strength, ductility, thermal conductivity, thermal expansion coefficient, and of course corrosion resistance. No material has yet been identified that is completely immune to cracking in supercritical units.
5
Prešern, Andreja. "Pathogen-Plant Interactions in Plant Membrane Perforation". En Socratic Lectures 8. University of Lubljana Press, 2023. http://dx.doi.org/10.55295/psl.2023.ii14.
Texto completoResumen
Plants are targets of many pathogens that produce a lot of different effectors to damage plant cells during infection. For plant survival, it is, therefore, crucial to possess an effi-cient immune system, which in contrast to mammalian immunity, consists only of in-nate immunity. Traditionally, plant immunity is divided into two branches, i.e. pat-tern-triggered (PTI) and effector-triggered immunity (ETI), but the accumulating knowledge has shown that the division cannot be strictly maintained. ETI coevolves with pathogen e fector molecules, which can function in many different ways to escape plant immunity and damage plant cells. Among their targets is the plant plasma membrane, which repre-sents an important cell barrier. There are several different tactics to bypass this barrier, e.g. membrane perforation by proteins or peptides, which is an important and ubiqui-tously found mechanism of toxicity as well as self-defense in all kingdoms of life. It can be used to get specific molecules from cells, for signaling, or even to deliver effector mol-ecules into the cytoplasm. The exact knowledge on plant membrane perforation, howev-er, is lacking, and the hidden details still await to be unveiled. Keywords: Plant immune System; Pathogen-Plant Interactions; Plant Membrane Perfora-tion
6
Popescu, Sorina. "Redox-sensitive thimet oligopeptidases TOP1 and TOP2 are required for immune signaling and systemic acquired immunity". En ASPB PLANT BIOLOGY 2020. USA: ASPB, 2020. http://dx.doi.org/10.46678/pb.20.1332401.
Texto completo
7
Yang, Leiyun. "A glycolytic enzyme negatively regulates immunity through repressing the expression of intracellular immune receptor NLR genes in Arabidopsis thaliana". En ASPB PLANT BIOLOGY 2020. USA: ASPB, 2020. http://dx.doi.org/10.46678/pb.20.1369186.
Texto completo
8
Chebotaryov, L. Yu y L. N. Valentovich. "The use of harpins as inducers of plant immunity". En 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/10.26907/978-5-00130-204-9-2019-467.
Texto completo
9
JAWAD, Israa, Adian Abd Alrazak DAKL y Hussein Jabar JASIM. "CHARACTERIZATION, MECHANISM OF ACTION, SOURCES TYPES AND USES OF THE ANTIMICROBIAL PEPTIDES IN DOMESTIC ANIMALS, REVIEW". En VII. INTERNATIONAL SCIENTIFIC CONGRESSOF PURE,APPLIEDANDTECHNOLOGICAL SCIENCES. Rimar Academy, 2023. http://dx.doi.org/10.47832/minarcongress7-13.
Texto completoResumen
This review aimed to identify the general characteristics of , mechanism of action, types and uses of antimicrobial peptides in animals, antimicrobial peptides were lass of small peptides that widely exist naturally, they varied greatly in structure, composition are found in the animal's species, and were standard structural features, twenty to sixty residue long, cationic and amphipathic peptides, have a positive charge that interacted with negatively charged molecules on the bacterial cell surfaces, a have an expansive field of inhibitory effects and were made as the first line of protection by both multicellular organisms. An essential component of the innate immune method of various organisms can have broad movement to instantly destroy bacteria, parasites, yeasts, fungi, viruses, and even cancer cells, Several antimicrobial peptides were expressed in the gastrointestinal mucosa of the animals where they can modulate innate immune responses and the intestinal microbial, act some protective microbial species and modulate an immune response. Its interactions with innate immunity and the intestinal microbial reveal attractive drug targets, act as a new therapeutic approach against gastrointestinal infections, damage, and inflammations, and modulate obesity and metabolic diseases. In addition, its acts as a biomarker of gastrointestinal diseases. They have been useful parts of the host's defense systems for a long time. Because microbes become resistant to antimicrobial peptides more slowly than to traditional antibiotics, they could be used as alternative treatments in the future. Several thousand antimicrobial peptides have been isolated from microorganisms, plants, insects, crustaceans, creatures, and even humans. Conclusion: Antimicrobial peptides are small proteins found in plant and animal species. They are the first defense against infections caused by microorganisms. and work against a wide range of bacteria, fungi, and viruses, both gram-positive and gram-negative. They are related together to innate immunity and adaptive immunity.
10
Kuzmina, L. P., E. S. Tsidilkovskaya y A. G. Khotuleva. "CHANGES IN SCREENING MARKERS OF THE IMMUNE STATUS OF WORKERS AT A LEAD RECYCLING PLANT". En The 17th «OCCUPATION and HEALTH» Russian National Congress with International Participation (OHRNC-2023). FSBSI «IRIOH», 2023. http://dx.doi.org/10.31089/978-5-6042929-1-4-2023-1-269-272.
Texto completoResumen
The problem of the adverse effect of lead on human health currently remains relevant, especially in occupational medicine. One of the targets of the toxic effect of lead is the immune system, which determines the relevance of research aimed at assessing the immune status of workers in contact with lead and its compounds. The purpose of this study was to evaluate changes in the screening markers of the immune status (leukocyte parameters, immunoglobulins of classes A, M, G) in workers of a lead recycling plant. Materials and methods. The main group — 49 employees of the plant for the recycling of lead-containing products with a length of service of 7 (3; 9) years, the control group — 23 men working without contact with harmful occupational factors. A laboratory examination was carried out, including the study of the blood lead level, ALA in the urine, leukocyte counts and immunoglobulins of classes A, M, G. Results. An inverse correlation was found between the level of IgA in workers of a lead recycling plant with length of service (r=–0.393, p=0.005) in the absence of age dependence, with the blood lead level (r=-0.313, p=0.027). Also, the dependence of the levels of immunoglobulins of classes A, M, G on the concentration of ALA in the urine was revealed: at the level of ALA in the urine ≥20 μmol/gCR, the levels of immunoglobulins are significantly lower than at ALA <20 μmol/gCR. Conclusion. The revealed trend towards a decrease in humoral immunity with higher ALA values in the urine, a decrease in IgA with an increase in length of service indicate the effect of lead and its compounds on the state of humoral immunity and determine the significance of studying changes in IgA, IgM and IgG in dynamics in workers of a lead recycling plant for optimization of preventive measures.
Informes sobre el tema "Plant immunty"
1
Avni, Adi y Gitta L. Coaker. Proteomic investigation of a tomato receptor like protein recognizing fungal pathogens. United States Department of Agriculture, enero de 2015. http://dx.doi.org/10.32747/2015.7600030.bard.
Texto completoResumen
Maximizing food production with minimal negative effects on the environment remains a long-term challenge for sustainable food production. Microbial pathogens cause devastating diseases, minimizing crop losses by controlling plant diseases can contribute significantly to this goal. All plants possess an innate immune system that is activated after recognition of microbial-derived molecules. The fungal protein Eix induces defense responses in tomato and tobacco. Plants recognize Eix through a leucine-rich-repeat receptor- like-protein (LRR-RLP) termed LeEix. Despite the knowledge obtained from studies on tomato, relatively little is known about signaling initiated by RLP-type immune receptors. The focus of this grant proposal is to generate a foundational understanding of how the tomato xylanase receptor LeEix2 signals to confer defense responses. LeEix2 recognition results in pattern triggered immunity (PTI). The grant has two main aims: (1) Isolate the LeEix2 protein complex in an active and resting state; (2) Examine the biological function of the identified proteins in relation to LeEix2 signaling upon perception of the xylanase elicitor Eix. We used two separate approaches to isolate receptor interacting proteins. Transgenic tomato plants expressing LeEix2 fused to the GFP tag were used to identify complex components at a resting and activated state. LeEix2 complexes were purified by mass spectrometry and associated proteins identified by mass spectrometry. We identified novel proteins that interact with LeEix receptor by proteomics analysis. We identified two dynamin related proteins (DRPs), a coiled coil – nucleotide binding site leucine rich repeat (SlNRC4a) protein. In the second approach we used the split ubiquitin yeast two hybrid (Y2H) screen system to identified receptor-like protein kinase At5g24010-like (SlRLK-like) (Solyc01g094920.2.1) as an interactor of LeEIX2. We examined the role of SlNRC4a in plant immunity. Co-immunoprecipitation demonstrates that SlNRC4a is able to associate with different PRRs. Physiological assays with specific elicitors revealed that SlNRC4a generally alters PRR-mediated responses. SlNRC4a overexpression enhances defense responses while silencing SlNRC4 reduces plant immunity. We propose that SlNRC4a acts as a non-canonical positive regulator of immunity mediated by diverse PRRs. Thus, SlNRC4a could link both intracellular and extracellular immune perception. SlDRP2A localizes at the plasma membrane. Overexpression of SlDRP2A increases the sub-population of LeEIX2 inVHAa1 endosomes, and enhances LeEIX2- and FLS2-mediated defense. The effect of SlDRP2A on induction of plant immunity highlights the importance of endomembrane components and endocytosis in signal propagation during plant immune . The interaction of LeEIX2 with SlRLK-like was verified using co- immunoprecipitation and a bimolecular fluorescence complementation assay. The defence responses induced by EIX were markedly reduced when SlRLK-like was over-expressed, and mutation of slrlk-likeusing CRISPR/Cas9 increased EIX- induced ethylene production and SlACSgene expression in tomato. Co-expression of SlRLK-like with different RLPs and RLKs led to their degradation, apparently through an endoplasmic reticulum-associated degradation process. We provided new knowledge and expertise relevant to expression of specific be exploited to enhance immunity in crops enabling the development of novel environmentally friendly disease control strategies.
2
Sessa, Guido y Gregory B. Martin. molecular link from PAMP perception to a MAPK cascade associated with tomato disease resistance. United States Department of Agriculture, enero de 2012. http://dx.doi.org/10.32747/2012.7597918.bard.
Texto completoResumen
The research problem: The detection of pathogen-associated molecular patterns (PAMPs) by plant pattern recognition receptors (PRRs) is a key mechanism by which plants activate an effective immune response against pathogen attack. MAPK cascades are important signaling components downstream of PRRs that transduce the PAMP signal to activate various defense responses. Preliminary experiments suggested that the receptor-like cytoplasmickinase (RLCK) Mai5 plays a positive role in pattern-triggered immunity (PTI) and interacts with the MAPKKK M3Kε. We thus hypothesized that Mai5, as other RLCKs, functions as a component PRR complexes and acts as a molecular link between PAMP perception and activation of MAPK cascades. Original goals: The central goal of this research was to investigate the molecular mechanisms by which Mai5 and M3Kε regulate plant immunity. Specific objectives were to: 1. Determine the spectrum of PAMPs whose perception is transmitted by M3Kε; 2. Identify plant proteins that act downstream of M3Kε to mediate PTI; 3. Investigate how and where Mai5 interacts with M3Kε in the plant cell; 4. Examine the mechanism by which Mai5 contributes to PTI. Changes in research directions: We did not find convincing evidence for the involvement of M3Kε in PTI signaling and substituted objectives 1 and 3 with research activities aimed at the analysis of transcriptomic profiles of tomato plants during the onset of plant immunity, isolation of the novel tomato PRR FLS3, and investigation of the involvement of the RLCKBSKs in PTI. Main achievements during this research program are in the following major areas: 1. Functional characterization of Mai5. The function of Mai5 in PTI signaling was demonstrated by testing the effect of silencing the Mai5 gene by virus-induced gene silencing (VIGS) experiments and in cell death assays. Domains of Mai5 that interact with MAPKKKs and subcellular localization of Mai5 were analyzed in detail. 2. Analysis of transcriptional profiles during the tomato immune responses to Pseudomonas syringae (Pombo et al., 2014). We identified tomato genes whose expression is induced specifically in PTI or in effector-triggered immunity (ETI). Thirty ETI-specific genes were examined by VIGS for their involvement in immunity and the MAPKKK EPK1, was found to be required for ETI. 3. Dissection of MAP kinase cascades downstream of M3Kε (Oh et al., 2013; Teper et al., 2015). We identified genes that encode positive (SGT and EDS1) and negative (WRKY1 and WRKY2) regulators of the ETI-associated cell death mediated by M3Kε. In addition, the MKK2 MAPKK, which acts downstream of M3Kε, was found to interact with the MPK3 MAPK and specific MPK3 amino acids involved interaction were identified and found to be required for induction of cell death. We also identified 5 type III effectors of the bacterial pathogen Xanthomonaseuvesicatoria that inhibited cell death induced by components of ETI-associated MAP kinase cascades. 4. Isolation of the tomato PRR FLS3 (Hind et al., submitted). FLS3, a novel PRR of the LRR-RLK family that specifically recognizes the flagellinepitope flgII-28 was isolated. FLS3 was shown to bind flgII-28, to require kinase activity for function, to act in concert with BAK1, and to enhance disease resistance to Pseudomonas syringae. 5. Functional analysis of RLCKs of the brassinosteroid signaling kinase (BSK) family.Arabidopsis and tomato BSKs were found to interact with PRRs. In addition, certain ArabidospsisBSK mutants were found to be impaired in PAMP-induced resistance to Pseudomonas syringae. Scientific and agricultural significance: Our research activities discovered and characterized new molecular components of signaling pathways mediating recognition of invading pathogens and activation of immune responses against them. Increased understanding of molecular mechanisms of immunity will allow them to be manipulated by both molecular breeding and genetic engineering to produce plants with enhanced natural defense against disease.
3
Sessa, Guido y Gregory Martin. role of FLS3 and BSK830 in pattern-triggered immunity in tomato. United States Department of Agriculture, enero de 2016. http://dx.doi.org/10.32747/2016.7604270.bard.
Texto completoResumen
Pattern-recognition receptors (PRRs) located on the plant cell surface initiate immune responses by perceiving conserved pathogen molecules known as pathogen-associated molecular patterns (PAMPs). PRRs typically function in multiprotein complexes that include transmembrane and cytoplasmickinases and contribute to the initiation and signaling of pattern-triggered immunity (PTI). An important challenge is to identify molecular components of PRR complexes and downstream signaling pathways, and to understand the molecular mechanisms that mediate their function. In research activities supported by BARD-4931, we studied the role of the FLAGELLIN SENSING 3 (FLS3) PRR in the response of tomato leaves to flagellin-derivedPAMPs and PTI. In addition, we investigated molecular properties of the tomato brassinosteroid signaling kinase 830 (BSK830) that physically interacts with FLS3 and is a candidate for acting in the FLS3 signaling pathway. Our investigation refers to the proposal original objectives that were to: 1) Investigate the role of FLS3 and its interacting proteins in PTI; 2) Investigate the role of BSK830 in PTI; 3) Examine molecular and phosphorylation dynamics of the FLS3-BSK830 interaction; 4) Examine the possible interaction of FLS3 and BSK830 with Pstand Xcveffectors. We used CRISPR/Cas9 techniques to develop plants carrying single or combined mutations in the FLS3 gene and in the paralogsFLS2.1 and FLS2.2 genes, which encode the receptor FLAGELLIN SENSING2 (FLS2), and analyzed their function in PTI. Domain swapping analysis of the FLS2 and FLS3 receptors revealed domains of the proteins responsible for PAMP detection and for the different ROS response initiated by flgII-28/FLS3 as compared to flg22/FLS2. In addition, in vitro kinase assays and point mutations analysis identified FLS2 and FLS3 domains required for kinase activity and ATP binding. In research activities on tomato BSK830, we found that it interacts with PRRs and with the co-receptor SERK3A and PAMP treatment affects part of these interactions. CRISPR/Cas9 bsk830 mutant plants displayed enhanced pathogen susceptibility and reduced ROS production upon PAMP treatment. In addition, BSK830 interacted with 8 Xanthomonastype III secreted effectors. Follow up analysis revealed that among these effectors XopAE is part of an operon, is translocated into plant cells, and displays E3 ubiquitinligase activity. Our investigation was also extended to other Arabidopsis and tomato BSK family members. Arabidopsis BSK5 localized to the plant cell periphery, interacted with receptor-like kinases, and it was phosphorylatedin vitro by the PEPR1 and EFRPRRs. bsk5 mutant plants displayed enhanced susceptibility to pathogens and were impaired in several, but not all, PAMP-induced responses. Conversely, BSK5 overexpression conferred enhanced disease resistance and caused stronger PTI responses. Genetic complementation suggested that proper localization, kinase activity, and phosphorylation by PRRs are critical for BSK5 function. BSK7 and BSK8 specifically interacted with the FLS2 PRR, their respective mutant plants were more susceptible to B. cinereaand displayed reduced flg22-induced responses. The tomato BSK Mai1 was found to interact with the M3KMAPKKK, which is involved in activation of cell death associated with effector-triggered immunity. Silencing of Mai1 in N. benthamianaplants compromised cell death induced by a specific class of immune receptors. In addition, co-expression of Mai1 and M3Kin leaves enhanced MAPKphosphorylation and cell death, suggesting that Mai1 acts as a molecular link between pathogen recognition and MAPK signaling. Finally, We identified the PP2C phosphatase Pic1 that acts as a negative regulator of PTI by interacting with and dephosphorylating the receptor-like cytoplasmickinase Pti1, which is a positive regulator of plant immunity. The results of this investigation shed new light on the molecular characteristics and interactions of components of the immune system of crop plants providing new knowledge and tools for development of novel strategies for disease control.
4
Alfano, James, Isaac Barash, Thomas Clemente, Paul E. Staswick, Guido Sessa y Shulamit Manulis. Elucidating the Functions of Type III Effectors from Necrogenic and Tumorigenic Bacterial Pathogens. United States Department of Agriculture, enero de 2010. http://dx.doi.org/10.32747/2010.7592638.bard.
Texto completoResumen
Many phytopathogenic bacteria use a type III protein secretion system (T3SS) to inject type III effectors into plant cells. In the experiments supported by this one-year feasibility study we investigated type III effector function in plants by using two contrasting bacterial pathogens: Pseudomonas syringae pv. tomato, a necrotrophic pathogen and Pantoea agglomerans, a tumorigenic pathogen. The objectives are listed below along with our major conclusions, achievements, and implications for science and agriculture. Objective 1: Compare Pseudomonas syringae and Pantoea agglomerans type III effectors in established assays to test the extent that they can suppress innate immunity and incite tumorigenesis. We tested P. agglomerans type III effectors in several innate immunity suppression assays and in several instances these effectors were capable of suppressing plant immunity, outputs that are suppressed by P. syringae effectors. Interestingly, several P. syringae effectors were able to complement gall production to a P. agglomerans pthGmutant. These results suggest that even though the disease symptoms of these pathogens are dramatically different, their type III effectors may function similarly. Objective 2: Construct P. syringae mutants in different combinations of type III-related DNA clusters to reduce type III effector redundancy. To determine their involvement in pathogenicity we constructed mutants that lack individual and multiple type III-related DNA clusters using a Flprecombinase-mediated mutagenesis strategy. The majority of single effector mutants in DC3000 have weak pathogenicity phenotypes most likely due to functional redundancy of effectors. Supporting this idea, Poly-DNAcluster deletion mutants were more significantly reduced in their ability to cause disease. Because these mutants have less functional redundancy of type III effectors, they should help identify P. syringae and P. agglomerans effectors that contribute more significantly to virulence. Objective 3: Determine the extent that P. syringae and P. agglomerans type III effectors alter hormone levels in plants. Inhibition of auxin polar transport by 2,3,5-triiodobenzoic acid (TIBA) completely prevented gall formation by P. agglomerans pv. gypsophilae in gypsophila cuttings. This result supported the hypothesis that auxin and presumably cytokinins of plant origin, rather than the IAA and cytokinins secreted by the pathogen, are mandatory for gall formation. Transgenic tobacco with pthGshowed various phenotypic traits that suggest manipulation of auxin metabolism. Moreover, the auxin levels in pthGtransgenic tobacco lines was 2-4 times higher than the control plants. External addition of auxin or cytokinins could modify the gall size in gypsophila cuttings inoculated with pthGmutant (PagMx27), but not with other type III effectors. We are currently determining hormone levels in transgenic plants expressing different type III effectors. Objective 4: Determine whether the P. agglomerans effectors HsvG/B act as transcriptional activators in plants. The P. agglomerans type III effectors HsvG and HsvB localize to the nucleus of host and nonhost plants and act as transcription activators in yeast. Three sites of adjacent arginine and lysine in HsvG and HsvB were suspected to act as Nuclear localization signals (NLS) domains. A nuclear import assay indicated two of the three putative NLS domains were functional NLSs in yeast. These were shown to be active in plants by fusing HsvG and HsvB to YFP. localization to the nucleus was dependent on these NLS domains. These achievements indicate that our research plan is feasible and suggest that type III effectors suppress innate immunity and modulate plant hormones. This information has the potential to be exploited to improve disease resistance in agricultural crops.
5
Chejanovsky, Nor y Bruce A. Webb. Potentiation of pest control by insect immunosuppression. United States Department of Agriculture, julio de 2004. http://dx.doi.org/10.32747/2004.7587236.bard.
Texto completoResumen
Our original aims were to elucidate the mechanisms through which the immunosuppressive insect virus, the Campoletis sonorensis polydnavirus (CsV) promotes replication of a well-characterized pathogenic virus, the Autographa californica multiple nucleopolyhedrovirus (AcMNPV) in hosts that are mildly or non-permissive to virus replication. According to the BARD panels criticism we modified our short-term goals (see below). Thus, in this feasibility study (one-year funding) we aimed to show that: 1. S. littoralis larvae mount an immune response against a baculovirus infection. 2. Immunosuppression of an insect pest improves the ability of a viral pathogen (a baculovirus) to infect the pest. 3. S. littoralis cells constitute an efficient tool to study some aspects of the anti- viral immune response. We achieved the above objectives by: 1. Finding melanized viral foci upon following the baculoviral infection in S . littoralis larvae infected with a polyhedra - positive AcMNPV recombinant that expressed the GFP gene under the control of the Drosophila heat shock promoter. 2. Studying the effect of AcMNPV-infection in S . littoralis immunosuppressed by parasitation with the Braconidae wasp Chelonus inanitus that bears the CiV polydna virus, that resulted in higher susceptibility of S. littoralis to AcMNPV- infection. 3. Proving that S. littoralis hemocytes resist AcMNPV -infection. 4. Defining SL2 as a granulocyte-like cell line and demonstrating that as littoralis hemocytic cell line undergoes apoptosis upon AcMNPV -infection. 5. Showing that some of the recombinant AcMNPV expressing the immuno-suppressive polydna virus CsV- vankyrin genes inhibit baculoviral-induced lysis of SL2 cells. This information paves the way to elucidate the mechanisms through which the immuno- suppressive polydna insect viruses promote replication of pathogenic baculoviruses in lepidopteran hosts that are mildly or non-permissive to virus- replication by: - Assessing the extent to which and the mechanisms whereby the immunosuppressive viruses, CiV and CsV or their genes enhance AcMNPV replication in polydnavirus- immunosuppressed H. zea and S. littoralis insects and S. littoralis cells. - Identifying CiV and CsV genes involved in the above immunosuppression (e.g. inhibiting cellular encapsulation and disrupting humoral immunity). This study will provide insight to the molecular mechanisms of viral pathogenesis and improve our understanding of insect immunity. This knowledge is of fundamental importance to controlling insect vectored diseases of humans, animals and plants and essential to developing novel means for pest control (including baculoviruses) that strategically weaken insect defenses to improve pathogen (i.e. biocontrol agent) infection and virulence.
6
Sessa, Guido y Gregory Martin. MAP kinase cascades activated by SlMAPKKKε and their involvement in tomato resistance to bacterial pathogens. United States Department of Agriculture, enero de 2012. http://dx.doi.org/10.32747/2012.7699834.bard.
Texto completoResumen
The research problem: Pseudomonas syringae pv. tomato (Pst) and Xanthomonas campestrispv. vesicatoria (Xcv) are the causal agents of tomato bacterial speck and spot diseases, respectively. These pathogens colonize the aerial parts of the plant and cause economically important losses to tomato yield worldwide. Control of speck and spot diseases by cultural practices or chemicals is not effective and genetic sources of resistance are very limited. In previous research supported by BARD, by gene expression profiling we identified signaling components involved in resistance to Xcvstrains. Follow up experiments revealed that a tomato gene encoding a MAP kinase kinase kinase (MAPKKKe) is required for resistance to Xcvand Pststrains. Goals: Central goal of this research was to investigate the molecular mechanisms by which MAPKKKεand associated MAP kinase cascades regulate host resistance. Specific objectives were to: 1. Determine whether MAPKKKεplays a broad role in defense signaling in plants; 2. Identify components of MAP kinase cascades acting downstream of MAPKKKε; 3. Determine the role of phosphorylation-related events in the function of MAPKKKε; 4. Isolate proteins directly activated by MAPKKKε-associatedMAPK modules. Our main achievements during this research program are in the following major areas: 1. Characterization of MAPKKKεas a positive regulator of cell death and dissection of downstream MAP kinase cascades (Melech-Bonfil et al., 2010; Melech-Bonfil and Sessa, 2011). The MAPKKKεgene was found to be required for tomato resistance to Xcvand Pstbacterial strains and for hypersensitive response cell death triggered by different R gene/effector gene pairs. In addition, overexpression analysis demonstrated that MAPKKKεis a positive regulator of cell death, whose activity depends on an intact kinase catalytic domain. Epistatic experiments delineated a signaling cascade downstream of MAPKKKεand identified SIPKK as a negative regulator of MAPKKKε-mediated cell death. Finally, genes encoding MAP kinase components downstream of MAPKKKεwere shown to contribute to tomato resistance to Xcv. 2. Identification of tomato proteins that interact with MAPKKKεand play a role in plant immunity (Oh et al., 2011). We identified proteins that interact with MAPKKKε. Among them, the 14-3-3 protein TFT7 was required for cell death mediated by several R proteins. In addition, TFT7 interacted with the MAPKK SlMKK2 and formed homodimersin vivo. Thus, TFT7 is proposed to recruit SlMKK2 and MAPKKK client proteins for efficient signal transfer. 3. Development of a chemical genetic approach to identify substrates of MAPKKKε-activated MAP kinase cascades (Salomon et al., 2009, 2011). This approach is based on engineering the kinase of interest to accept unnatural ATP analogs. For its implementation to identify substrates of MAPKKKε-activated MAP kinase modules, we sensitized the tomato MAP kinase SlMPK3 to ATP analogs and verified its ability to use them as phosphodonors. By using the sensitized SlMPK3 and radiolabeled N6(benzyl)ATP it should be possible to tag direct substrates of this kinase. 4. Development of methods to study immunity triggered by pathogen-associated molecular patterns (PAMPs) in tomato and N. benthamiana plants (Kim et al., 2009; Nguyen et al. 2010). We developed protocols for measuring various PTI-associatedphenotypes, including bacterial populations after pretreatment of leaves with PAMPs, induction of reporter genes, callose deposition at the cell wall, activation of MAP kinases, and a luciferase-based reporter system for use in protoplasts. Scientific and agricultural significance: Our research activities discovered and characterized a signal transduction pathway mediating plant immunity to bacterial pathogens. Increased understanding of molecular mechanisms of immunity will allow them to be manipulated by both molecular breeding and genetic engineering to produce plants with enhanced natural defense against disease. In addition, we successfully developed new biochemical and molecular methods that can be implemented in the study of plant immunity and other aspects of plant biology.
7
Chejanovsky, Nor y Bruce A. Webb. Potentiation of Pest Control by Insect Immunosuppression. United States Department of Agriculture, enero de 2010. http://dx.doi.org/10.32747/2010.7592113.bard.
Texto completoResumen
The restricted host range of many baculoviruses, highly pathogenic to Lepidoptera and non-pathogenic to mammals, limits their use to single or few closely related Lepidopteran species and is an obstacle to extending their implementation for pest control. The insect immune response is a major determinant of the ability of an insect pathogen to efficiently multiply and propagate. We have developed an original model system to study the Lepidopteran antiviral immune response based on Spodoptera littoralis resistance to AcMNPV (Autographa californica multiple nucleopolyhedrovirus) infection and the fascinating immunosuppressive activity of polydnaviruses .Our aim is to elucidate the mechanisms through which the immunosuppressive insect polydnaviruses promote replication of pathogenic baculoviruses in lepidopteran hosts that are mildly or non-permissive to virus- replication. In this study we : 1- Assessed the extent to which and the mechanisms whereby the immunosuppressive Campoletis sonorensis polydnavirus (CsV) or its genes enhanced replication of a well-characterized pathogenic baculovirus AcMNPV, in polydnavirus-immunosuppressedH. zea and S. littoralis insects and S. littoralis cells, hosts that are mildly or non-permissive to AcMNPV. 2- Identified CsV genes involved in the above immunosuppression (e.g. inhibiting cellular encapsulation and disrupting humoral immunity). We showed that: 1. S. littoralis larvae mount an immune response against a baculovirus infection. 2. Immunosuppression of an insect pest improves the ability of a viral pathogen, the baculovirus AcMNPV, to infect the pest. 3. For the first time two PDV-specific genes of the vankyrin and cystein rich-motif families involved in immunosuppression of the host, namely Pvank1 and Hv1.1 respectively, enhanced the efficacy of an insect pathogen toward a semipermissive pest. 4. Pvank1 inhibits apoptosis of Spodopteran cells elucidating one functional aspect of PDVvankyrins. 5. That Pvank-1 and Hv1.1 do not show cooperative effect in S. littoralis when co-expressed during AcMNPV infection. Our results pave the way to developing novel means for pest control, including baculoviruses, that rely upon suppressing host immune systems by strategically weakening insect defenses to improve pathogen (i.e. biocontrol agent) infection and virulence. Also, we expect that the above result will help to develop systems for enhanced insect control that may ultimately help to reduce transmission of insect vectored diseases of humans, animals and plants as well as provide mechanisms for suppression of insect populations that damage crop plants by direct feeding.
8
Fluhr, Robert y Maor Bar-Peled. Novel Lectin Controls Wound-responses in Arabidopsis. United States Department of Agriculture, enero de 2012. http://dx.doi.org/10.32747/2012.7697123.bard.
Texto completoResumen
Innate immune responses in animals and plants involve receptors that recognize microbe-associated molecules. In plants, one set of this defense system is characterized by large families of TIR–nucleotide binding site–leucine-rich repeat (TIR-NBS-LRR) resistance genes. The direct interaction between plant proteins harboring the TIR domain with proteins that transmit and facilitate a signaling pathway has yet to be shown. The Arabidopsis genome encodes TIR-domain containing genes that lack NBS and LRR whose functions are unknown. Here we investigated the functional role of such protein, TLW1 (TIR LECTIN WOUNDRESPONSIVE1). The TLW1 gene encodes a protein with two domains: a TIR domain linked to a lectin-containing domain. Our specific aim in this proposal was to examine the ramifications of the TL1-glycan interaction by; A) The functional characterization of TL1 activity in the context of plant wound response and B) Examine the hypothesis that wounding induced specific polysaccharides and examine them as candidates for TL-1 interactive glycan compounds. The Weizmann group showed TLW1 transcripts are rapidly induced by wounding in a JA-independent pathway and T-DNA-tagged tlw1 mutants that lack TLW1 transcripts, fail to initiate the full systemic wound response. Transcriptome methodology analysis was set up and transcriptome analyses indicates a two-fold reduced level of JA-responsive but not JA-independent transcripts. The TIR domain of TLW1 was found to interact directly with the KAT2/PED1 gene product responsible for the final b-oxidation steps in peroxisomal-basedJA biosynthesis. To identify potential binding target(s) of TL1 in plant wound response, the CCRC group first expressed recombinant TL1 in bacterial cells and optimized conditions for the protein expression. TL1 was most highly expressed in ArcticExpress cell line. Different types of extraction buffers and extraction methods were used to prepare plant extracts for TL1 binding assay. Optimized condition for glycan labeling was determined, and 2-aminobenzamide was used to label plant extracts. Sensitivity of MALDI and LC-MS using standard glycans. THAP (2,4,6- Trihydroxyacetophenone) showed minimal background peaks at positive mode of MALDI, however, it was insensitive with a minimum detection level of 100 ng. Using LC-MS, sensitivity was highly increased enough to detect 30 pmol concentration. However, patterns of total glycans displayed no significant difference between different extraction conditions when samples were separated with Dionex ICS-2000 ion chromatography system. Transgenic plants over-expressing lectin domains were generated to obtain active lectin domain in plant cells. Insertion of the overexpression construct into the plant genome was confirmed by antibiotic selection and genomic DNA PCR. However, RT-PCR analysis was not able to detect increased level of the transcripts. Binding ability of azelaic acid to recombinant TL1. Azelaic acid was detected in GST-TL1 elution fraction, however, DHB matrix has the same mass in background signals, which needs to be further tested on other matrices. The major findings showed the importance of TLW1 in regulating wound response. The findings demonstrate completely novel and unexpected TIR domain interactions and reveal a control nexus and mechanism that contributes to the propagation of wound responses in Arabidopsis. The implications are to our understanding of the function of TIR domains and to the notion that early molecular events occur systemically within minutes of a plant sustaining a wound. A WEB site (http://genome.weizmann.ac.il/hormonometer/) was set up that enables scientists to interact with a collated plant hormone database.
9
Sessa, Guido y Gregory Martin. Role of GRAS Transcription Factors in Tomato Disease Resistance and Basal Defense. United States Department of Agriculture, 2005. http://dx.doi.org/10.32747/2005.7696520.bard.
Texto completoResumen
The research problem: Bacterial spot and bacterial speck diseases of tomato are causedby strains of Xanthomonas campestris pv. vesicatoria (Xcv) and Pseudomonas syringae pv.tomato (Pst), respectively. These bacteria colonize aerial parts of the plant and causesignificant losses in tomato production worldwide. Protection against Xcv and Pst bycultural practices or chemical control has been unsuccessful and there are only limitedsources of genetic resistance to these pathogens. In previous research supported in part byBARD IS-3237-01, we extensively characterized changes in tomato gene expression uponthe onset of spot and speck disease resistance. A remarkable finding of these studies wasthe inducibility in tomato leaves by both Xcv and Pst strains of genes encodingtranscriptional activator of the GRAS family, which has not been previously linked todisease resistance. Goals: Central goals of this research were to investigate the role of GRAS genes in tomatoinnate immunity and to assess their potential use for disease control.Specific objectives were to: 1. Identify GRAS genes that are induced in tomato during thedefense response and analyze their role in disease resistance by loss-of-function experiments.2. Overexpress GRAS genes in tomato and characterize plants for possible broad-spectrumresistance. 3. Identify genes whose transcription is regulated by GRAS family. Our main achievements during this research program are in three major areas:1. Identification of tomato GRAS family members induced in defense responses andanalysis of their role in disease resistance. Genes encoding tomato GRAS family memberswere retrieved from databases and analyzed for their inducibility by Pst avirulent bacteria.Real-time RT-PCR analysis revealed that six SlGRAS transcripts are induced during theonset of disease resistance to Pst. Further expression analysis of two selected GRAS genesshowed that they accumulate in tomato plants in response to different avirulent bacteria orto the fungal elicitor EIX. In addition, eight SlGRAS genes, including the Pst-induciblefamily members, were induced by mechanical stress in part in a jasmonic acid-dependentmanner. Remarkably, SlGRAS6 gene was found to be required for tomato resistance to Pstin virus-induced gene silencing (VIGS) experiments.2. Molecular analysis of pathogen-induced GRAS transcriptional activators. In aheterologous yeast system, Pst-inducible GRAS genes were shown to have the ability toactivate transcription in agreement with their putative function of transcription factors. Inaddition, deletion analysis demonstrated that short sequences at the amino-terminus ofSlGRAS2, SlGRAS4 and SlGRAS6 are sufficient for transcriptional activation. Finally,defense-related SlGRAS proteins were found to localize to the cell nucleus. 3. Disease resistance and expression profiles of transgenic plants overexpressing SlGRASgenes. Transgenic plants overexpressing SlGRAS3 or SlGRAS6 were generated. Diseasesusceptibility tests revealed that these plants are not more resistant to Pst than wild-typeplants. Gene expression profiles of the overexpressing plants identified putative direct orindirect target genes regulated by SlGRAS3 and SlGRAS6. Scientific and agricultural significance: Our research activities established a novel linkbetween the GRAS family of transcription factors, plant disease resistance and mechanicalstress response. SlGRAS6 was found to be required for disease resistance to Pstsuggesting that this and possibly other GRAS family members are involved in thetranscriptional reprogramming that takes place during the onset of disease resistance.Their nuclear localization and transcriptional activation ability support their proposed roleas transcription factors or co-activators. However, the potential of utilizing GRAS familymembers for the improvement of plant disease resistance in agriculture has yet to bedemonstrated.
10
Gafni, Yedidya y Vitaly Citovsky. Inactivation of SGS3 as Molecular Basis for RNA Silencing Suppression by TYLCV V2. United States Department of Agriculture, noviembre de 2013. http://dx.doi.org/10.32747/2013.7593402.bard.
Texto completoResumen
The Israeli isolate of Tomato yellow leaf curl geminivirus(TYLCV-Is) is a major tomato pathogen, causing extensive crop losses in Israel and in the south-eastern U.S. Yet, little is known about the molecular mechanisms of its interaction with tomato cells. One of the most interesting aspects of such interaction is how the invading virus counteracts the RNA silencing response of the plant. In the former BARD project, we have shown that TYLCV-Is V2 protein is an RNA silencing suppressor, and that this suppression is carried out via the interaction of V2 with the SGS3 component of the plant RNA silencing machinery. This reported project was meant to use our data as a foundation to elucidate the molecular mechanism by which V2 affects the SGS3 activity. While this research is likely to have an important impact on our understanding of basic biology of virus-plant interactions and suppression of plant immunity, it also will have practical implications, helping to conceive novel strategies for crop resistance to TYLCV-Is. Our preliminary data in regard to V2 activities and our present knowledge of the SGS3 function suggest likely mechanisms for the inhibitory effect of V2 on SGS3. We have shown that V2 possess structural and functional hallmarks of an F-box protein, suggesting that it may target SGS3 for proteasomal degradation. SGS3 contains an RNA-binding domain and likely functions to protect the cleavage produces of the primary transcript for subsequent conversion to double-stranded forms; thus, V2 may simply block the RNA binding activity of SGS3. V2 may also employ a combination of these mechanisms. These and other possibilities were tested in this reported project.