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Descripción
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| Understanding host-pathogen co-evolution is a central question in Biology as it is at the root of pathogen emergence, host switch and host range expansion, and the composition and dynamics of ecosystems. However, contrary to agroecosystems, evidences for plant-pathogen co-evolution in wild environments are almost non-existent for plant viruses. Thus, we propose to use as a model system the wild pepper Capsicum annuum var. aviculare (chile chiltepin), which is considered as the wild ancestor of the domesticated C. annuum species. Wild populations of chiltepin are found in the tropical dry forests of Mexico (1), where they are exploited for their small pungent fruits, and their cultivation by traditional local farmers has recently started in several regions. A large collection of samples representing wild and cultivated chiltepin populations in Mexico has been obtained (2), and the infecting viruses have been identified. Resistance to tobamoviruses in Capsicum spp. is controlled by alleles at the L locus. The L resistance gene has recently been cloned and characterised (3). This resistance is based on a single-gene locus encoding a CC-NB-LRR protein, which targets the coat protein (CP) of tobamoviruses. This recognition initiates signalling pathways leading to resistance by hypersensitive response (HR). In this study, the L gene frequency was assessed in each chiltepin populations. Interestingly, the frequency of this resistance gene is significantly higher in the wild populations than in the cultivated ones, which suggests that the pre-domestication of this species was not focused on the tobamoviruses resistance. Furthermore, the analysis of more than 100 full-length L gene sequences showed a high variability and a strong geographical structure of this gene. Local adaptations of chiltepin populations toward different tobamovirus pathotypes and/or different environmental conditions could explain the genetic structure of the L gene in Mexico. In addition, several sites under positive selection and co-variations were detected, mainly located in the domain involved in the CP recognition. The roles of these sites on the recognition of viral pathotypes at different environmental conditions will be further investigated. Altogether, these results suggest that the L resistance gene is a target for selection, which could support the hypothesis of co-evolution between chiltepin populations and tobamoviruses in wild ecosystems. | |
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Internacional
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Si |
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Nombre congreso
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14e Rencontrs de Virologie Végétale |
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Tipo de participación
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960 |
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Lugar del congreso
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Aussois (Francia) |
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Revisores
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Si |
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ISBN o ISSN
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00-0000-00 |
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DOI
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Fecha inicio congreso
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13/01/2013 |
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Fecha fin congreso
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17/01/2013 |
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Desde la página
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7 |
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Hasta la página
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7 |
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Título de las actas
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Résumés |