Discerning the relationship between geminiviral infection and vesicle trafficking using virus induced gene silencing

Tomato yellow leaf curl disease is one of the most important threats to tomato crops worldwide. One of its causal agents, Tomato yellow leaf curl Sardinian virus (TYLCSV) is a monopartite member of the genus Begomovirus from the family Geminiviridae. Due to the few proteins encoded by their viral genome, geminiviruses rely heavily on host cellular machineries and interact with a wide range of plant proteins to complete all processes required for infection, such as viral replication, movement and suppression or evasion of plant defence mechanisms. The identification of the host proteins involved in viral infection will be an important step towards the understanding of the mechanisms underlying this process. In our laboratory, transgenic Nicotiana benthamiana plants containing a green fluorescent protein (GFP) expression cassette flanked by two direct repeats of the intergenic region of TYLCSV have been constructed (2IR plants). When these plants are infected with TYLCSV, an overexpression of the reporter gene is observed in those cells where the virus is actively replicating. These plants have been used together with virus induced gene silencing (VIGS) in an effort to identify host genes involved in the infection process using a reverse genetics approach. Using this combined technique our group has identified two genes δ-COP and ARF 1, involved in retrograde vesicle trafficking, which are essential for the infectious process. We are currently assaying genes codifying proteins involved in different pathways of the vesicle trafficking system: Sar1b, γ subunit of AP1, Sec24, SYT1 and two that encode the heavy chain of triskelion proteins. Their effect over viral infection will be presented and discussedUniversidad de Málaga. Campues de Excelencia Internacional Andalucía Tech

Geminiviral protein Rep interferes in PCNA sumoylation

Rep is a multifunctional protein essential for replication of geminivirus that interferes with the sumoylation of a key protein in the DNA replication, PCNA (Proliferating Cell Nuclear Antigen). It is known that Rep is capable of interacting with a plethora of plant proteins, including PCNA. Despite the biological significance remains unknown, it’s thought that this interaction should play a key role for generating new copies of the virus genome. Therefore, in order to characterize this interaction, we study which lysines are sumoylated in tomato PCNA (SlPCNA). Considering conservation, location and presence of sumoylation domain criteria, we have identified some candidate lysines and studied how its mutation affects this protein sumoylation in Escherichia coli assays. Finally, we plan to confirm and characterize the Rep interference on SlPCNA sumoylation and determine if this interference occurs in planta.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Identifying the function of vesicle trafficking in geminiviral infection using virus induced gene silencing

Tomato yellow leaf curl Sardinian virus (TYLCSV) is one of the causal agent of the tomato yel-low leaf curl disease, one of the most important threats to tomato crops worldwide. TYLCSV is a monopartite member of the genus Begomovirus from the family Geminiviridae. To carry out a full infection, geminiviruses need to move inside the infected cell and from one cell to an-other for which they depend on diverse cellular factors. While cell-to-cell movement has been described to occur through plasmodesmata, the way in which geminiviruses move inside the host cells is yet unknown. The identification of the host proteins involved in viral infection will be an important step to-wards the understanding of the mechanisms underlying this process. In our laboratory, trans-genic Nicotianabenthamiana plants containing a green fluorescent protein (GFP) expression cassette flanked by two direct repeats of the intergenic region of TYLCSV have been construct-ed (2IR plants). When these plants are infected with TYLCSV, an overexpression of the reporter gene is observed in those cells where the virus replicates. These plants have been used to-gether with virus induced gene silencing (VIGS) in an effort to identify host genes involved in the infection process using a reverse genetics approach. Using this combined technique our group has identified two genes δ-COP and ARF 1, involved in retrograde vesicle trafficking, which are essential for the infectious process. We are current-ly assaying genes codifying proteins involved in different pathways of the vesicle trafficking system: Sar1b, γ subunit of AP1, Sec24, SYT1 and two that encode the heavy chain of triskelion proteins. Their effect over virus infection will be presented and discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Estructura sectorial en las regiones de Colombia un análisis para el período 1992-2005

En el estudio de las condiciones competitivas de un sector es necesario entender las características estructurales de las regiones en donde se ubican. La localización espacial y la eficiencia de la organización industrial son primordiales para dinamizar la productividad de la industria. Las economías de urbanización (condiciones básicas de competitividad), las economías de localización (que crean la aglomeración de firmas) y la dinámica de la organización industrial (combinación factorial) son clave para la eficiencia de los mercados. Este trabajo busca estudiar esas condiciones en tres regiones de Colombia: Medellín-Valle de Aburrá, Bogotá-Soacha y Barranquilla-Soledad a partir de las condiciones de organización industrial de los sectores: Alimentos (311), Bebidas (313) y Confecciones (322).51 p.Contenido parcial: Evolución reciente de la economía regional Colombiana -- Análisis de los sectores en las regiones -- El Modelo -- Conclusiones

A viral effector suppresses cell-to-cell spread of silencing by targeting two plasmodesmal receptor-like kinases

RNA interference (RNAi) in plants can move from cell to cell, allowing for systemic spread of an anti-viral immune response. How this cell-to-cell spread of silencing is regulated is currently unknown. Here, we describe that the C4 protein from Tomato yellow leaf curl virus can inhibit the intercellular spread of RNAi. Using this viral protein as a probe, we have identified the receptor-like kinase (RLK) BARELY ANY MERISTEM 1 (BAM1) as a positive regulator of the cell-to-cell movement of RNAi, and determined that BAM1 and its closest homologue, BAM2, play a redundant role in this process. C4 interacts with the intracellular domain of BAM1 and BAM2 at the plasma membrane and plasmodesmata, the cytoplasmic connections between plant cells, interfering with the function of these RLKs in the cell-to-cell spread of RNAi. Our results identify BAM1 as an element required for the cell-to-cell spread of RNAi and highlight that signalling components have been co-opted to play multiple functions in plants.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Effector-mediated suppression of plant defense against biotrophs through activation of antagonistic defense against necrotrophs

Plant hormones are small molecules involved in the regulation of plant growth, development, reproduction and stress responses. Salicylic acid (SA) and jasmonates (JA) are essential for the activation of defence responses against pathogens. SA signaling is involved in triggering immunity against biotrophic pathogens while JA activates resistance against necrotrophic pathogens. The SA and JA pathways are mostly antagonistic: elevated biotroph resistance correlates with increased necrotroph susceptibility, and vice versa. Using transcriptomics to look for a functional overlap between plant gene silencing and type III-mediated plant responses we found that genes associated to JA signaling were overrepresented in the overlapping set, more so than SA-related genes. We present here the results of the ensuing analysis, showing effector-mediated activation of the JA pathway as a virulence mechanism, and establishing a novel role for gene silencing in the regulation of the JA pathway.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech - See more at: http://riuma.uma.es/xmlui/handle/10630/5393/submit/12176e8e39815b4d6112192a6815221718868c2f.continue#sthash.RYCQTkwy.dpu

Geminivirus Rep Protein Interferes with the Plant DNA Methylation Machinery and Suppresses Transcriptional Gene Silencing

Viruses are masters at circumventing host defenses and manipulating the cellular environment for their own benefit. The replication of the largest known family of single-stranded DNA viruses, Geminiviridae, is impaired by DNA methylation but the fact that plants might use methylation as a defense against geminiviruses and the impact that viral genome methylation may have during the infection, remain controversial. We have found that geminiviruses reduce the expression of the plant maintenance DNA methyltransferases, MET1 and CMT3, in both, locally and systemically infected tissues. Furthermore, we demonstrated that the virus-mediated repression of these two maintenance DNA methyltransferases is widely spread among different geminivirus species and we have identified Rep as the geminiviral protein responsible for the repression of MET1 and CMT3. The presence of Rep, suppresses transcriptional gene silencing (TGS) of an Arabidopsis transgene and of host loci whose expression is strongly controlled by MET1. Bisulfite sequencing analyses showed that the expression of Rep caused a substantial reduction in the levels of DNA methylation at certain loci at CG sites. The biological relevance of these findings and the role of Rep as a TGS suppressor will be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Representación de la distribución diatópica de algunos procesos fonológicos del español de Colombia según el ALEC

Este artículo presenta la distribución diatópica de los procesos fonológicos de elisión, debucalización, velarización y deslateralización de la palatal que afectan a los fonemas /s/, /r/, /n/, /ʝ/ y /ʎ/ en una selección de mapas fonéticos del Atlas Lingüístico-Etnográfico de Colombia, ALEC. El objetivo principal es proponer una discusión con los estudios más recientes acerca de la distribución de dichos procesos fonológicos en el país, para así establecer un estado del arte que sirva de insumo para el diseño del cuestionario fonético del Nuevo Atlas Lingüístico-Antropológico de Colombia (NALAC). Como resultados se especifican las zonas exactas de distribución de los fenómenos en cuestión, mientras que la literatura al respecto tendía a la generalización de zonas dialectales más amplias

Geminivirus C2 protein represses genes involved in sulphur assimilation and this effect can be counteracted by jasmonate treatment

Geminiviruses are plant viruses that infect a broad range of crops and cause extensive losses worldwide, having an important economic impact. C2, a multifunctional pathogenicity factor encoded by geminiviruses, has been recently shown to suppress the responses to jasmonates in the host plant, which might at least partially explain its well-established role in pathogenicity. Sulphur is one of the essential macro-elements for plant life, and is considered to have a role in plant defence, in a phenomenon named sulphur-induced resistance (SIR) or sulphur-enhanced defence (SED). In this work, we show that geminivirus C2 protein represses the expression of genes involved in the sulphur assimilation pathway in Arabidopsis, but, interestingly, this effect can be neutralized by exogenous jasmonate treatment. These preliminary results may raise the idea that geminiviruses might be affecting sulphur metabolism, and maybe counteracting SIR/SED, through the manipulation of the jasmonate signalling pathway, which would define a novel strategy in plant-virus interactions and may unveil SIR/SED as an important player in the plant defence against viruses.Ministerio de Ciencia y Innovación/FEDER AGL2007-66062-C02-02/AGR AGL2010-22287-CO2European Regional Development Fund (ERDF) BIO2010-15201Junta de Andalucía BIO­27