Biological and molecular characterisation of Pilidium lythri , an emerging strawberry pathogen in Iran

Strawberry production is hampered by numerous biotic factors including fungal pathogens. Symptoms of dark brown necrotic lesions on fruits, stems and leaves were observed in a survey of strawberry fields in the Kurdistan province of Iran. Symptomatic plant tissues were collected and several fungal isolates were recovered from these tissues. Based on a combination of morphological characteristics and sequence data for ITS and LSU ribosomal DNA, the isolates were identified as Pilidium lythri (previously named P. concavum or Hainesia lythri ). A pathogenicity assay confirmed that all new isolates induced symptoms resembling those observed in the field, as well as two P. lythri isolates from olive included in the assay; no significant disease incidence or severity differences were detected between isolates. This is the first report of P. lythri on strawberry in Iran. Genetic diversity between Pilidium lythri isolates from strawberry (18 isolates) and olive (two isolates) was evaluated using RAPD and M13 markers. No polymorphism was detected within and among the isolates, indicating limited genetic variability probably due to lack of recombination events and/or recent introduction. Given recent outbreaks and the presence of the pathogen in most strawberry growing areas in the Kurdistan province, quickly applied and appropriate management programmes are necessary to prevent spread of the disease.