Development of a polymerase chain reaction (PCR) assay for the specific detection of Biscogniauxia mediterranea living as an endophyte in oak tissues

The present work reports the development of a PCR assay to detect the ascomycete Biscogniauxia mediterranea in asymptomatic tissues of Quercus cerris. To this purpose, two specific primers (MED1 and MED2) were designed by comparison of sequences comprised between ITS1 and ITS4 generic primers of 21 isolates of B. mediterranea and related species. Specificity of the primers was tested against 19 isolates of B. mediterranea and 20 isolates of related and unrelated genera, and against Quercus cerris DNA. The reliability of the results was confirmed by Southern Blot analysis. The 2 specific primers MED1 and MED2 were able to detect B. mediterranea DNA in the host tissues at picogram quantity of target DNA. This assay would greatly enhance the possibility to study the presence and localization of B. mediterranea during its latent phase in Quercus species.