Archivio Journal of Plant Pathology

Abstract:

Creeping bellflower (Campanula rapuncoloides L.) is a popular flowering plant commonly used in parks and gardens in northern Italy, belonging to Campanulaceae. In August 2016, plants of Campanula rapuncoloides grown in a garden located near Biella (Latitude: 45°36′00″N, Longitude: 8°03′00″E) showed leaf chlorosis followed by the appearance of orange pulverulent rust pustules irregularly distributed in the abaxial surface of leaves. Orange uredinia were circular to elliptic, 0.2 to 0.45 mm in diameter. Orange urediniospores were catenulate, ovoid or ellipsoid, ranging from 14.3 to 16.4 µm in length by 30.8 to 34.4 µm in width. Teleutospores were not observed. The morphological characteristics of the fungus corresponded to those of the genus Coleosporium (Cummins, 1978). The Internal Transcribed Spacer (ITS) region of rDNA from urediniospores was amplified using the primers ITS1/ITS4 and sequenced. The 420 bp product was sequenced (Genbank Accession No. KY296542) and showed a 99% similarity with Coleosporium campanulae (KP017555). Pathogenicity was confirmed by spraying an urediniospores suspension at 1x105 /ml on three plants of C. rapuncoloides grown in 3 l-pot. The same number of control plants were sprayed with sterile water. Plants were kept at 20°C to 23°C for 5 days in a dew chamber. All inoculated plants developed typical rust symptoms with the uredinia appearing after 10 days. Although C. campanulae is reported in several European countries on different spontaneous native plants including the campanula host genus (Helfer, 2013), this is, to our knowledge, the first report of C. campanulae on cultivated C. rapuncoloides in Italy.