Morphological and molecular identification of Leptosphaeria maculans in canola seeds and flowers collected from the North Iran

Blackleg disease, caused by Leptosphaeria maculans, is one of the most important diseases of rapeseed Brassica napus in Iran as in other regions of the world. The samples including canola petals and seeds were collected during 2014–2015 from canola field in North Iran. Isolates characteristics of fungus were assessed based on the colony growth rate and pycnidia in Potato Dextrose Agar. The pycnidia of the fungus were black, globose to subglobose in shape, the single-celled conidia, hyaline and fusiform with diameters of 4–5 × 1.5–2 μm. Most of the isolates were produced pigment in the liquid culture in variable color brown to black. Thirteen isolates were then separated into pathogenicity groups based on the interactions on B. napus differential cultivars. For the direct detection of seed contamination with L. maculans, PCR was developed using specific primers pair (LmacF, LmacR) which can amplify ITS1 and ITS2 along with the 5.8S rRNA region of L. maculans genome. Based on the followed information and sequence analysis, the fungal isolates from these samples were identified as L. maculans. The findings of this research showed that the disease was aggressive and highly distributed from infested seeds to oilseed rape fields.