The genetic variation and population structure of Soybean mosaic virus (SMV) in Iran was analysed through the characterization of a set of isolates collected in the soybean-growing provinces of Iran. The partial nucleotide sequence of these isolates showed a single, undifferentiated population with low genetic diversity, highly differentiated from other SMV world populations. These traits are compatible with a population bottleneck associated with the recent introduction of SMV in Iran. Phylogenetic analyses suggest that SMV was introduced into Iran from East Asia, with at least three introduction events. The limited genetic diversification of SMV in Iran may be explained by strong negative selection in most viral genes eliminating the majority of mutations, together with recombination purging deleterious mutations. The pathogenicity of Iranian SMV isolates was typified on a set of soybean differential lines either susceptible or carrying different resistance genes or alleles to SMV. Two pathotypes were distinguished according to the ability to overcome Rsv4 resistance in line V94-5152. Amino acid sequence comparisons of virulent and avirulent isolates on V94-5152 (Rsv4), plus site-directed mutagenesis in a biologically active cDNA clone, identified mutation S1053N in the P3 protein as the determinant for virulence on V94-5152. Codon 1053 was shown to be under positive selection, and S1053N-determined Rsv4-virulence occurred in isolates with different genealogies. The V94-5152 (Rsv4)-virulence determinant in Iranian isolates maps into a different amino acid position in the P3 protein than those previously reported, indicating different evolutionary pathways towards resistance breaking that might be conditioned by sequence context. The GenBank/EMBL/DDBJ accession numbers for the Soybean mosaic virus isolates analysed in this study are KF135467,

<p>Olive knot is an important disease in most countries where olives are commercially grown. In the spring of 2015, some galls were observed on the trunk and branches of 4-year-old olive trees in the north of Iran. The bacteria were isolated from galls and all isolates were gram-negative, aerobic, and capable of producing florescent pigment. Other phenotypic characteristics of the isolates were assessed. Pathogenicity tests were carried out on olive branches incubated with different isolates. Primary symptoms were observed after two weeks. Sequences of 16S rRNA and RNA polymerase beta subunit genes of pathogenic isolates were completely similar to <em>Pseudomonas savastanoi </em>pv. <em>savastanoi </em>(Smith 1908) Young et al<em>.</em> 1978 in GenBank. Based on the results from phenotypic analyses, pathogenicity tests and phylogenetic data, the isolates were identified as <em>P. savastanoi </em>pv. <em>savastanoi</em>. The host range of our isolates was specific to olive trees. None of the inoculated oleander (<em>Nerium oleander </em>L.), winter jasmine (<em>Jasminum nudiflorum </em><a title="John Lindley" href="https://en.wikipedia.org/wiki/John_Lindley">Lindl.</a>), Japanese privet (<em>Ligustrum japonicum</em> Thunb.) and ash (<em>Fraxinus excelsior </em>L.) developed disease symptoms. No difference in disease resistance was observed between six studied olive cultivars. There was no olive tree or orchard around the studied orchard as far as more than one kilometer. As the disease agent listed in Iran’s foreign quarantine pests and diseases list, appropriate quarantine and phytosanitary measures were undertaken to eradicate the disease.</p>