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Abstract

The present report describes the new occurrence of Tomato mosaic virus (ToMV) in cabbage, bean and Malva neglecta plants in Iran. In this study, sequence analyses of a partial RNA dependent RNA polymerases (RdRp) and complete movement protein (MP) and the coat protein (CP) nucleotide sequences of three new ToMV isolates collected from major crop fields in Iran revealed low genetic variation of RdRp gene compared to the CP and MP genes. The different topologies of the phylogenetic trees constructed, using available open reading frame (ORF1), ORF2 and ORF3 sequences from ToMV isolates, indicated different evolutionary constraints in these genomic regions. Statistical analysis also revealed that with the exception of CP other tested ToMV genes were under negative selection and the RdRp gene was under the strongest constraints. According to the phylogenetic tree it can be inferred from the nucleotide sequences of the complete CP and MP genes, that isolates from Iran and Egypt formed separate groups, irrespective of host origin. However, isolates clustered into groups with correlation to geographic origin but not the host. Analysis of the Ks *, Z* and Snn values also indicated genetic differentiation between ToMV populations. The Tajima’s D, Fu and Li’s statistical values were significantly negative for the RdRp gene of the Asian population which suggests the sudden expansion of ToMV in Asia. Taken together, the results indicate that negative selection and genetic drift were important evolutionary factors driving the genetic diversification of ToMV.
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Abstract

Pedunculate and sessile oaks (Quercus robur L.; Q. petraea [Matt] Liebl.) often coexist in mixed forest stands. However, species-specific investigations and forest management actions in such populations require reliable methods of identification of the species status of individuals. We investigated genetic diversity and species differentiation of adult and naturally established seedling cohorts in a mixed forest stand composed of Q. robur and Q. petraea, located in the Jamy Nature Reserve in north-central Poland. Using nineteen nuclear microsatellite loci and a model-based clustering approach as a tool for species delineation, we efficiently identified 105 and 60 adults, as well as 191 and 456 seedlings of pedunculate and sessile oaks, respectively. While the adult trees of both species were randomly distributed throughout the sample plot, the seedlings demonstrated significant spatial clustering, which was particularly evident for Q. petraea. The two oak species exhibited similar levels of genetic diversity in adult and offspring cohorts. Inbreeding was found to be low and significant only at the stage of seedlings. The estimates of effective population size were higher for Q. robur than Q. petraea, despite the overall greater reproductive success of the later one. There was a significant level of differentiation between the studied oak species, as measured by Fst coefficient (0.084 – adults; 0.099 – seedlings). The results on genetic diversity and species differentiation obtained in the studied indigenous near-natural stand of Q. robur and Q. petraea could be considered as a reference for other population genetic studies of oaks.
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