Archivio Journal of Plant Pathology

Abstract:

In 2015, rot symptoms were observed during storage on pomegranate fruit (Punica granatum L.) cvs Wonderful and Mollar de Elche from a packinghouse in Apulia (Southern Italy). Symptoms, observed on 26% of fruit, consisted of circular brownish-yellow lesions, beginning in the crown area and quickly expanding to entire fruit, with softening of the tissues including arils. Tissue portions were cut from surface-sterilized fruit and incubated on semi-selective PDA at 28±1°C in the dark. Colonies were white to creamy, leathery, and covered by abundant dark-greenish- brown to black spherical pycnidia (80-140 μm in diameter) with thin membranous walls. Hyphae were septate, and conidia hyaline, one-celled, 10-17.5×2-5 μm, ellipsoid to fusiform, straight or slightly curved. These characteristics corresponded to Pilidiella granati (Saccardo) (syn. Coniella granati Sacc.) Petr. & Syd.). For molecular confirmation, fungal DNA was amplified using universal primers ITS5/ITS4. BLAST analysis of the 506 bp amplicon (GenBank accession No. KU821701) showed 100% identity with other P. granati ITS sequences. For pathogenicity tests, surface-sterilized fruit of both cvs were wounded (5×5 mm), inoculated by a mycelial plug and incubated as reported above. Sterile plugs were used as controls. Lesions were visible after five days only on inoculated fruit. The re-isolated fungus corresponded to P. granati, which was reported as pomegranate postharvest rot agent in Spain (Palou et al., 2010) and recently associated with a crown rot in Italy (Pollastro et al., 2016). To our knowledge, this is the first report of P. granati rot on harvested pomegranate fruit in Southern Italy that might represent a serious threat for marketing of this promising crop.