شانکر و سرخشکیدگی گل رز در اثر قارچ Colletotrichum fructicola در ایران

Rose (Rosa sp.) has become one of the most popular flowers in the world because of its ornamental and medicinal values, and its cultivation is continuously increasing. This perennial flowering plant belongs to the Rosaceae family and is cultivated in greenhouses and open fields. Samples with symptoms of canker and dieback were collected from the varieties of Samurai and Jumelia from greenhouses in the Chaharmahal and Bakhtiari province. The symptoms were observed as a diedack with cankers at the border of healthy and infected tissues and the creation of U-shaped patterns on the stem due to the formation of perithecia. colony formed with a diameter of 70 mm on PDA culture medium at a temperature of 25 °C and a light cycle of 12 h of darkness and 12 h of light for one week. The aerial mycelia formed felt colony in the center and were flat at the periphery. After 10 days, the white color changed to gray from the center of the petri to the periphery. The 50 mm diameter on the PCA culture medium was a mixture of white and gray color with a lower density of aerial mycelium than on the PDA culture medium, and only on this culture medium was the perithecia. On the OA culture medium, the 60 mm-diameter, flat, without aerial mycelium, its color was white in the center and dark brown in the periphery; the mycelia were light, smooth, branched, with a thick wall, 3-6 µm in diameter. Single-celled conidia with thin wall, hyaline, cylindrical, smooth with rounded ends. The size of conidia was 3.19-4 × 11.2-16.2 μm, and large numbers were formed in conidiomata on SNA culture medium. Appressorium from mycelia was light to dark brown in color, club-shaped, spherical, ovoed, and sometimes with various shapes measuring 5.6-6.7 x 7.8-9.6 μm. there were The Perithecia were dark to light brown in color, spherical to pyriform, with a thick wall and covered with hyphal outgrowths, diameter 75.5-105.7 μm, and ascospores were hyaline, slightly curved, smooth, single-celled. had a size of 3.8-4.5 x 13-17 μm. DNA was extracted from the fungal mycelia, and ITS region and TUB2 gene were amplified and sequenced by polymerase chain reaction. Using the results obtained from the morphological characteristics and analysis of the ITS and TUB2 regions, the fungal isolates were identified as Colletotrichum fructicola. To perform the pathogenicity test, a suspension with a concentration of 106 spores per milliliter was prepared from seven-day-old colony grown on PDA culture medium and inoculated into a two-month-old rose. Fungal species were isolated from necrotic symptoms and Koch's postulates were confirmed. To our knowledge, this is the first report of canker disease caused by C. fructicola on roses in the world