Development of a SCAR Marker-Based Diagnostic Method for the Detection of the Citrus Target Spot Pathogen Pseudofabraea citricarpa.

Target spot, a recently observed citrus disease that is caused by Pseudofabraea citricarpa, can cause substantial economic losses in citrus production. In this study, a 797 bp marker specific to Ps. citricarpa was identified via random amplified polymorphic DNA (RAPD) technique. The primer pair Pc-SFP/Pc-SRP, which was designed from RAPD amplicons, was utilized as a sequence-characterized amplified region (SCAR) marker. This marker identified Ps. citricarpa with a single and distinct band of 389 bp but did not amplify DNA from other tested fungal species. The PCR assay was highly sensitive to the target DNA at picogram levels and could reliably amplify Ps. citricarpa sequences with the Pc-SFP/Pc-SRP primer pair. The SCAR marker that was identified in the present study can facilitate rapid decision-making and precise disease forecasting and management.