Development of a new LAMP assay for the fast diagnosis of Elsinoë fawcettii

The ascomycete fungus Elsinoë fawcettii Bitancourt and Jenkins (Myrianginoeaceae, Elsinoaceae) is a quarantined organism in the EU as it can cause important diseases (citrus scab, sour orange rind and common rind) on Citrus species, cultivars and hybrids. As the disease is still restricted to Georgia in the EPPO region, the possibility to rely on accurate and solid diagnostic protocols to unequivocally identify E. fawcettii, even at its latent stage, would be of great importance in order to prevent its possible introduction in uncontaminated areas and to control its impact. Traditional diagnosis of this fungus can be troublesome and time consuming, requiring well-furnished laboratories and expert operators with skills in mycology. DNA-based detection could therefore enable to overcome these drawbacks and allow a rapid, sensitive and accurate diagnosis of the pathogen. Recently, PCR and qPCR-based assays have been developed, able to simultaneously detect different pathogens affecting Citrus species, including E. fawcettii. To further improve detection efficiency, in this work a species-specific assay based on Loop mediated isothermal AMPlification (LAMP) reaction was developed. Results proved the high specificity of the protocol, able to detect as low as 1.00 pg/ µL of pathogen DNA in less than 30 minutes. The accuracy of the assay and its compatibility with a user-friendly, portable LAMP device, make this real-time monitoring method a tool of choice for routine phytosanitary control of plant material, which could profitably assist in the diagnosis, surveillance and control of E. fawcettii.