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Gomez P.,CSIC - Center of Edafology and Applied Biology of the Segura | Gomez P.,University of Exeter | Sempere R.N.,CSIC - Center of Edafology and Applied Biology of the Segura | Sempere R.N.,Bioprodin SL | And 3 more authors.
European Journal of Plant Pathology

Pepino mosaic virus (PepMV) is an emerging pathogen that causes severe economic losses in tomato crops in the Northern hemisphere. After its first identification, the new viral strain PepMV-CH2 has been isolated in several countries worldwide. In order to further understand the evolutionary dynamics of PepMV before and after PepMV-CH2 emergence, we analyzed a collection of PepMV isolates from southeastern Spain, estimating the rate of PepMV molecular evolution and the coalescence process for the effective number of PepMV infections using a Bayesian phylogenetic approach. Our results show that the rate of PepMV molecular evolution was 5. 570 × 10 -3 substitutions/site/year, a value which is approximately an order of magnitude higher than the rates recently reported for other plant RNA viruses. Moreover, PepMV-CH2 was estimated to have originated in 2000, coincident with the onset of PepMV-CH2 infections in southeastern Spain, its population following now an expansion process. This further illustrates that genetic and ecological interactions among different viral strains can modulate the evolutionary dynamics of PepMV and determine its epidemiological profile. © 2012 KNPV. Source

Carretero-Paulet L.,Institute Biologia Molecular Y Celular Of Plantas Ibmcp Csic Upv | Fares M.A.,Institute Biologia Molecular Y Celular Of Plantas Ibmcp Csic Upv | Fares M.A.,Trinity College Dublin
Molecular Biology and Evolution

Gene duplicates are a major source of evolutionary novelties in the form of new or specialized functions and play a key role in speciation. Gene duplicates are generated through whole genome duplications (WGD) or small-scale genome duplications (SSD). Although WGD preserves the stoichiometric relationships between duplicates, those arising from SSD are usually unbalanced and are expected to follow different evolutionary dynamics than those formed by WGD. To dissect the role of the mechanism of duplication in these differential dynamics and determine whether this role was shared across species, we performed a genome wide evolutionary analysis of gene duplications arising from the most recent WGD events and contemporary episodes of SSD in four model species representing distinct plant evolutionary lineages. We found an excess of relaxed purifying selection after duplication in SSD paralogs compared with WGD, most of which may have been the result of functional divergence events between gene copies as estimated by measures of genetic distances. These differences were significant in three angiosperm genomes but not in the moss species Physcomitrella patens. Although the comparison of models of evolution does not attribute a relevant role to the mechanism of duplication in the evolution duplicates, distribution of retained genes among Gene Ontology functional categories support the conclusion that evolution of gene duplicates depends on its origin of duplication (WGD and SSD) but, most importantly, on the species. Similar lineage-specific biases were also observed in protein network connectivity, translational efficiency, and selective constraints acting on synonymous codon usage. Although the mechanism of duplication may determine gene retention, our results attribute a dominant role to the species in determining the ultimate pattern of duplicate gene retention and reveal an unanticipated complexity in the evolutionary dynamics and functional specialization of duplicated genes in plants. © 2012 The Author. Source

Shimada T.,Japan National Agriculture and Food Research Organization | Endo T.,Japan National Agriculture and Food Research Organization | Fujii H.,Japan National Agriculture and Food Research Organization | Rodriguez A.,Fundecitrus | And 4 more authors.
Plant Science

Three cDNA clones from Satsuma mandarin (Citrus unshiu Marc.) were isolated and expressed in Escherichia coli. CuSTS3-1 and CuSTS3-2 encode linalool synthases and CuSTS4 encodes a nerolidol/linalool synthase. Transcripts of CuSTS3-1, CuSTS3-2 and CuSTS4 were abundant in young fruit at 60 days after flowering (DAF), flowers and leaves, respectively. Treatments with Xanthomonas citri subsp. citri (XCC), the causal agent of citrus canker and Penicillium italicum (PI), the cause of post-harvest fruit decay, and wounding up-regulated CuSTS3-1 in fruit and mainly CuSTS4 in leaves. Linalool, citral, geraniol and citronellol showed strong antibacterial and antifungal activities against XCC and PI in vitro, while most other mono-and sesquiterpenes, including limonene and gamma-terpinene, did not. Linalool, used at levels similar to those present in resistant Ponkan mandarin (Citrus reticulata Blanco) leaves, was able to inhibit growth of XCC in vitro. Compared to other five citrus types, linalool accumulated at extraordinarily high levels in Ponkan mandarin leaves and was released at high amounts from their leaves, while it was hardly detectable in the most susceptible species, indicating that linalool biosynthesis and accumulation might be involved in plant defense against bacterial and fungal pathogens and be associated with field resistance to citrus canker. © 2014 Elsevier Ireland Ltd. Source

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