Verticillium dahliae is an economically important pathogen causing vascular wilt on more than 160 plant species. Most strains have a wide host range. Forty-five wild isolates of V. dahlia recovered from different woody and herbaceous plants throughout Iran. genetic diversity of the isolates was assessed through vegetative compatibility groups (VCGs) using nitrate non-utilizing (nit) mutants. Nit mutants were generated using water agar supplemented with 5-7% KClO3. Nit mutants from different isolates were used in all possible combinations. Three VC local groups were identified and designated as VCGA, VCGB and VCGC which correspond to VCG2B (88.8%) and VCG 2A (8.8%) and weakly to VCG2A (2.2%) Most of the isolates were assigned to VCG2B. The results indicated that genetic diversity of V. dahliae is very low and there were no relationship between VCGs and geographicalorig in of the isolates. Host specificity of V. dahliae using 18 isolates was determined on 11 different hosts plant species. Different plants reacted differently to the isolates and were divided into three groups: very sensitive (eggplant, pistachio, cotton and okra), semi-sensitive (sunflower, radish and rapeseed) and low sensitive (pepper, tomato, small radish and cabbage). Each plant species reacted differently to each isolate. Mint was less sensitive to the pathogen (5 isolates) than other plant species tested.

The present study considers assessment of morphometry and genetic diversity of 24 populations of Hypnea. Statistical analyses indicated that characters such as algal branching in habit, size of alga and Position of tetrasporange sorus had the most important role in intera-specific variation. In both morphometry and genetic diversity analysis, grouping of the populations separated the studied species into four distinct clusters and groups but populations were spread in clusters. Analysis revealed significant genetic difference among populations and some degree of genetic admixture and gene exchange among the studied populations.

This study was conducted to evaluate genetic diversity in eight native populations of Iranian cucumber including Birjand, Roudbar, Gorgan, Kashan, Yazd, Taft, Sanandaj, and Isfahan in comparison with Super Daminus hybrid as control in a randomized complete block design with three replications for two years (2007 and 2008) in two regions (Varamin and Isfahan). Studied traits were days to flowering, number of fertile flowers, the ratio of female/ male flowers, number of branches, days to first harvest, average number of fruits per plant, weight of fruits per plant, average fruits length per population, the ratio of three first harvest / total yield and average yield per plant. The results indicated the existence of high genetic differences between local populations and Super Daminus hybrid. Based on cluster analysis, populations were classified in three groups. According to clusters segregation in the highest difference level, Super Daminus had the highest difference with other populations showing that this hybrid has a genetic different from other populations. After control cultivar, Yazd and Taft populations had the most differences with other populations, respectively. Maximum similarity was observed between Isfahan and Kashan populations and amang Gorgan, Roudbar and Sanandaj populations as well. Furthermore, Isfahan and Kashan populations were similar to Birjand population and three of them were somewhat similar to Gorgan, Roudbar and Sanandaj populations.

Objective: The aim of this study was to estimate genetic variability and phonetic relationships of 50 isolates of P. sojae from Iran.Methods: During 2005–2007, 142 isolates of Phytophthora sojae were collected from soil samples and diseased soybean plants from Lorestan, Mazandaran, Golestan and Ardabil provinces. Races of the isolates were determined. DNA of P. sojae fifty isolates was amplified with 20 RAPD and 5 ISSR primers.Results: Five primers amplified 77 fragments, of which 20 were polymorphic, indicating low variability. RAPD and ISSR primers clustered isolates into three distinct groups at 85% similarity. genetic diversity among isolates detected intra specific variability even among isolates of the same geographic origin. There is no correlation between races, geographical distribution, and molecular markers.