Javier Tabima
Botany & Plant Pathology
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Presentation Time: 
2015 - 3:45pm
Contrasting the genomes of sister taxa with narrow but different host ranges provides an ideal system for studying host adaptation. Selection pressures imposed by different hosts are expected to lead to adaptation by gradual divergence of populations and eventual speciation due to reproductive isolation. This process of host-mediated speciation is expected to leave signatures (such as mutations, recombination, indels, or duplications) in the corresponding pathogen genomes. Using paired-end approaches on the Illumina HiSeq2000 platform we sequenced and annotated the genomes of two sister species in the plant pathogen genus Phytophthora: P. rubi and P. fragariae to study which genomic signatures are involved in host adaptation (P. rubi and P. fragariae exclusively infects the genus Rubus or Fragariae respectively). Genomes were assembled using SOAPdenovo version 1.05. Gene calling was performed using MAKER, AUGUSTUS and SNAP. The genomes of P. rubi and P. fragariae yielded 9,434 scaffolds and an estimated 18,268 genes for P. rubi and 8,511 scaffolds and 17,832 genes for P. fragariae. Functional annotation shows a similar number of genes involved in different biochemical pathways, such as sugar processing, metabolism, and amino acid synthesis between the two species. Positive selection (dN/dS) was detected for three pairs of orthologous effector proteins in the RxLR class. Ongoing work is being conducted to identify other candidate genes under selection and genomic signatures that may have been involved in the process of speciation via host jumping