Development of PCR Assays for the Identification of Species and Pathotypes of Elsinoë Causing Scab on Citrus

ABSTRACT Two scab pathogens of citrus, Elsinoe fawcettii and E. australis, cause citrus scab and sweet orange scab, respectively, and pathotypes of each species have been described. The two species cannot be readily distinguished by morphological or cultural characteristics and can be distinguished only by host range and the sequence of the internal transcribed spacer (ITS) region. In this study, random amplified polymorphic DNA (RAPD) assays clearly distinguished E. fawcettii and E. australis, and the sweet orange and natsudaidai pathotypes within E. australis also could be differentiated. We developed specific primer sets, Efaw-1 for E. fawcettii; Eaut-1, Eaut-2, Eaut-3, and Eaut-4 for E. australis; and EaNat-1 and EaNat-2 for the natsudaidai pathotype within E. australis using RAPD products unique to each species or pathotype. Other primer sets, Efaw-2 and Eaut-5, which were specific for E. fawcettii and E. australis, respectively, were designed from previously determined ITS sequences. The Efaw-1 and ...