بیماری لکه برگی ناشی از Ectophoma iranica روی گل رز در ایران

Rose (Rosa sp.) is a perennial flowering plant belonging to the Rosaceae family. Due to its ornamental and medicinal values, the cultivation of roses is increasing, so that it is cultivated both in open fields and in greenhouse conditions. Following the sampling of leaf spot symptoms from the Jumlia rose variety from the Chaharmahal and Bakhtiari province, a fungus was isolated. The symptoms of this fungus were observed in the form of angular spots, along with dark brown and an orange border on the rose leaves. In severe cases, these spots joined each other and infected most of the leaf surface, causing the leaf to become fragile. At 25 °C and 12 h of darkness and 12 h of light, the fungus grew to 70 mm in the PDA culture medium in one week, due to this brown-colored colony growth with indented lines. On the OA culture medium, this isolate formed a flat, 60 mm diameter, without aerial mycelium, white in the center, and brown in the periphery. This fungus had walled, brown, and branched aerial hyphae, and the pycnidials were dark brown with thick walls, covered with hyphae, and formed singly or complex inside the culture medium. In terms of shape and size, they were spherical, ovoid, or amorphous, with a size of 280-430 µm, and one or two short necks. The walls of the pycnidials were composed of pseudoparenchymal and rectangular cells. Conidia were hyaline, oval, straight, and sometimes curved, with smooth and thin walls, aseptate, and with a size of 1.1-2.2 x 1.4-4.4 µm. To confirm morphological identification, DNA was extracted from fungal mycelia, and the ITS region and TUB2 gene were amplified by polymerase chain reaction. Using the results obtained from morphological characteristics and analysis of ITS and TUB2 regions, the fungal isolates were identified as Ectophoma iranica. To perform the pathogenicity test, mycelium discs were prepared from the seven-day-old progeny grown on PDA culture medium and inoculated on the leaves of a two-month-old Jumelia rose plant. Fungal species were isolated from necrotic symptoms and Koch's postulates were confirmed. To the best of our knowledge, this is the first report of the occurrence of leaf spot disease by E. iranica species on roses worldwide.