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Descripción
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| The acquisition of new hosts, or host range expansion, will provide a virus with more opportunities for transmission and survival, but may be limited by across-host fitness trade-offs, that is, increasing the fitness in a new host will decrease fitness in the original one. A major cause of across-host trade-offs in viruses is antagonistic pleiotropy. A relevant case of host range expansion is resistance-breaking (RB), in which viruses acquire the capacity to infect otherwise resistant plant genotypes. Under the gene-for-gene (GFG) model of host-pathogen interactions, resistance breaking should be associated to fitness costs in non-resistant hosts. RB-associated costs have been reported for tobamovirus pathotypes that overcome L-gen resistance in pepper (Fraile et al. 2011, 2014). To explore the causes of BR-associated costs, full-length infectious cDNA clones were obtained from two field isolates of Pepper mild mottle virus (PMMoV) that overcome L2 resistance. Then, all reported coat-protein mutations determining RB of alleles L3 and L4 were introduced, and the parental and mutant genotypes was assayed in the susceptible pepper genotypes L+/L+, L1/L1, L2/L2 and L3/L3. Virus accumulation was quantified as a proxy to fitness, and virulence was estimated as the decrease of plant biomass due to infection. Results show that virus fitness depended on the interaction virus genotype (G) x Environment (E), host genotype being the environment, indicating pleiotropic effects of RB mutations. When these effects were quantified, it was found that pleiotropy was antagonistic or positive depending on the specific RB mutation. Similarly, the fitness of the non-RB P0 pathotype isolates depended on the host plant. Last, RB-mutations also affected virulence, but fitness and virulence were not correlated. These results are significant as they show that selection for RB does depend not only on the resistance allele deployed but on the genotype of susceptible hosts. Thus, results stress the complexity of the mechanisms underlying host range expansion in viruses, and the difficulty of predicting the evolution of RB and, hence, of resistance durability. Also, these results are significant in that they will provide the bases for future model analyses of the evolution of resistance breaking under realistic scenarios. | |
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Internacional
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Si |
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Nombre congreso
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International Exploratory Workshop 2017: Ecological genomics of coevolutionary interactions |
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Tipo de participación
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960 |
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Lugar del congreso
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Zurich, Switzerland |
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Revisores
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Si |
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ISBN o ISSN
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0000-0000 |
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DOI
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Fecha inicio congreso
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08/01/2017 |
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Fecha fin congreso
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13/01/2017 |
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Desde la página
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1 |
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Hasta la página
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1 |
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Título de las actas
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Libro de resúmenes del congreso |