The phylogenetic diversity of 29 rhizobial strains nodulating Phaseolus vulgaris in Iran was analysed on the basis of their core and symbiotic genes. These strains displayed five 16S rRNA-RFLP patterns and belong to eight ERIC-PCR clusters. The phylogenetic analyses of 16S rRNA, recA and atpD core genes allowed the identification of several strains as Rhizobium sophoriradicis, R. leguminosarum, R. tropici and Pararhizobium giardinii, whereas other strains represented a new phylogenetic lineage related to R. vallis. These strains and those identified as R. sophoriradicis and R. leguminosarum belong to the symbiovar phaseoli carrying the γ nodC allele distributed in P. vulgaris endosymbionts in America, Europe, Africa and Asia. The strain identified as R. tropici belongs to the symbiovar tropici carried by strains of R. tropici, R. leucaenae, R. lusitanum and R. freirei nodulating P. vulgaris in America, Africa and Asia. The strain identified as P. giardinii belongs to the symbiovar giardinii together with the type strain of this species nodulating P. vulgaris in France. It is remarkable that the recently described species R. sophoriradicis is worldwide distributed in P. vulgaris nodules carrying the γ nodC allele of symbiovar phaseoli harboured by rhizobia isolated in the American distribution centers of this legume.

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The aim of this study was characterized Pectobacterium carotovorum subsp. carotovorum (Pcc) the causal pathogen of watermelon soft rot disease in Iran. Of fifty bacterial isolates with white grey and convex colonies on nutrient agar obtained from symptomatic watermelon, ten isolates were selected for further tests. Pathogenicity tests results showed that all test isolates developed typical water-soak symptoms after 2 days and signs of soft rot began 4 days after inoculation on watermelon fruits. Based on the phenotypic properties, the isolates were identified as Pectobacterium carotovorum subsp. carotovorum. The 16S rDNA sequences of isolates were 99% similar to the corresponding 16S rDNA sequence of the reference Pcc isolate. BOX and ERIC-PCR analysis indicated that genetic diversity was present among the isolated Pcc isolates did not relate to the geographic location isolated from. To the best of our knowledge, this is the first study of biochemical and genotypic characterization of Pcc isolates the causal agents of soft rot disease on watermelon, in Iran.

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In 2012, a leaf spot disease on walnut seedlings was observed in Hamedan province of Iran. The spots were necrotic with yellow halos. Symptomatic samples were collected and suspected bacterial agent was isolated on nutrient agar medium. Phenotypic characteristics such as production of fluorescent pigment on KB medium, LOPAT test and utilization of various carbon sources, revealed that the strains were Pseudomonas syringae pv. syringae. All tested strains were pathogenic on peach, plum and walnut seedling. To investigate the genetic diversity among the strains, rep-PCR using BOX and ERIC primers was performed. Results showed high similarity among the strains from the same region, while variation was found among those from different areas and they were divided into two groups based on geographic regions. The phylogenetic analysis based on 16S rRNA, rpoD and gyrB sequences showed that representative isolates were closely related to P. syringae pv. syringae. To the best of our knowledge, this is the first report of the presence of P. syringae pv. syringae as a causal agent of walnut seedlings leaf spot in Iran and worldwide.