Phenotypic and Genotypic Diversity of Boxwood Blight Causal Agent Populations in Iran

Caspian boxwood (Buxus hyrcana Pojark.) is one of the ever green hardwoods of Caspian sea forestes which, unfortunately; is endanger of overthrow. Furthermore, several hectares of its habitats in Gilan and west of Mazandaran are exposed to Blight and excessive wilt caused by Cylindrocladium buxicola, recently. This fungus is serious peril for survival and generation of these trees. Certainly, identification of this fungus characteristic can be benefit in election and development of management strategies. So this research with the aim of information increment about this fungus and its population features in Iran was carried out. Firstly, phenotype properties of C. buxicola isolates (including morphology and disease severity),which randomly have collected from different sites of boxwood habitats, were evaluated. Then genetic variety of the isolates was evaluated by rep-PCR markers. Based on morphological assessments including shape and growth of mycelium, length, shape and the number of septates of conidia, also length and vesicle characterization of stips, 52 obtained Iranian isolates identified as Calonectria pseudonaviculta. 21 representative isolates were selected based on pathogenicity.These isolateds showed different levels of pathogenicity. The results of banding patterns of rep markers were analyzed together and the 21 representative isolates categorized into 4 groups at 95% similarity, and they were scattered in three provinces. This investigation furthermore revealed that all examined isolates, belonged to the authentic Calonectria pseudonaviculta group having main and stable morpho-physiological characteristics, so it seems that in the disease control, the use of resistant cultivars is one.