Identification and Observation of Infection Processes of Species Associated with Pearl Plum Anthracnose in Guangxi, China.

Pearl plum ( Lindl.) is mainly cultivated in Tian'e County in Guangxi Province, southern China. Anthracnose is a devastating disease on pearl plum, causing extensive leaf blight. Diseased leaves were sampled from 21 orchards in Tian'e County. Isolates were first screened for ones resembling , and 21 representative isolates were selected for sequencing of portions of the ribosomal internal transcribed spacer (ITS), the intergenic region of apn2 and MAT1-2-1 genes (ApMAT), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), calmodulin (CAL), chitin synthase (CHS-1), and β-tubulin 2 (TUB2). Based on colony, conidial, and appressorial morphology and sequence analyses, the isolates associated with pearl plum anthracnose were identified as four species: (16 isolates), (3 isolates), (1 isolate), and (1 isolate). The results of pathogenicity tests showed that isolates of all four species were pathogenic to wounded leaves of pearl plum seedlings. In this study, we microscopically observed the infection processes of isolates of these four species on attached pearl plum leaves. For and , the entire infection processes took 120 h; for . and , it only took 72 h. This is the first report of and causing anthracnose on pearl plum worldwide, and also the first report of causing anthracnose on pearl plum in China.