Development of Molecular Marker to Detect Citrus Melanose Caused by Diaporthe citri from Citrus Melanose-like Symptoms

It is difficult to distinguish melanose and melanoses-like symptoms with the naked eye because they appear simi- lar. To accurately detect melanose symptoms caused by Diaporthe citri from melanose-like symptoms, we devel- oped PCR-based specific primers Dcitri by aligning the internal transcribed spacer (ITS) region of D. citri with the ITS of Diaporthe cytosporella, Diaporthe foeniculina, Colletotrichum gloeosporioides, Botrytis cinerea, Alter- naria citri, and Fusarium oxysporum found on citrus peel. PCR results showed that the specific product was amplified in D. citri but not in other isolates including, C. gloeosporioides, B. cinerea, A. citri, F. oxysporum. In addition, specific products were observed in melanose symptoms caused by D. citri but not in melanose-like symptoms, such as copper-injury, sunscald, damages by yellow tea thrips, and pink citrus rust mite. Using the Dcitri primers developed in this study, it is expected that melanose caused by D. citri could be accurately dis- tinguished from melanose-like symptoms.