FIRST REPORT OF LEAF SPOT OF CAMPANULA GLOMERATA CAUSED BY ALTERNARIA sp IN ITALY
A. Garibaldi, D. Bertetti, G. Ortu, M.L. Gullino
During Summer 2014, extensive necrosis were observed on Campanula glomerata plants grown in a private garden near the city of Biella (northern Italy). Pale-brown, irregular lesions were present on the leaves that wilted and rotted. When also the stems were affected, the plants died. A fungus was consistently isolated on potato dextrose agar (PDA) which, on potato carrot agar (PCA) produced a greenish mycelium, with brown, septate, ovoid, elliptical or obclavate conidia, measuring 8-33×6-11 μm (average: 15×8 μm). These morphometric traits allowed the identification of the pathogen as Alternaria sp. (Simmons, 2007). DNA was extracted using the NucleoSpin Plant kit (Macherey Nagel, Germany) and PCR amplification carried out using ITS1/ITS4 primers. The 484 bp amplified product was sequenced (GenBank accession No. KP225273) and a BLASTn search (Altschul et al., 1997) confirmed that the sequence corresponded to that of Alternaria sp. For pathogenicity tests, leaves of three healthy plants of C. glomerata were inoculated with disks excised from fungal colonies grown on PDA. Plants inoculated only with sterile PDA disks served as controls. All plants were covered with plastic bags and maintained at a temperature of 19 to 25°C. Seven days post inoculation, lesions developed only on inoculated leaves from which the same fungus used for inoculation was consistently reisolated. To the best of our knowledge this the first report of Alternaria sp. on C. glomerata in Italy and in the world.