Occurrence, Distribution, and Genomic Characteristics of Plum Pox Virus Isolates from Common Apricot (Prunus armeniaca) and Japanese Apricot (Prunus mume) in China

Abstract

Plum pox, or Sharka disease, caused by infection with plum pox virus (PPV), results in enormous economic losses to the stone fruit industry. However, the frequency and distribution of PPV remain unclear in China, the world’s largest stone fruit producer. Systemic visual surveys were performed on stone fruit trees in China from 2008 to 2018, and the results suggest that plum pox disease is widely distributed on common apricots (Prunus armeniaca) and Japanese apricots (Prunus mume), with an average symptoms incidence rate >30% in the latter. In samples collected from Beijing, Nanjing, Shanghai, Wuhan, Wuxi, and Yuncheng, PPV was detected in 77% (85 of 110) of collected samples by immunochromatographic (IC) strip tests and reverse transcription PCR, and 96% (67 of 70) of samples showing Sharka symptoms were PPV positive. Transmission electron microscopy revealed filamentous particles of ∼640 × 12.5 nm (n = 19) in size and pinwheel inclusions in symptomatic plants but not in the asymptomatic and PPV-negative plants. Full-length genomes were determined for four isolates (three from Japanese apricot and one from common apricot), and phylogenetic analyses indicated that all four isolates belong to a clade PPV-D, despite slight differences in genome size. These findings not only highlight the widespread occurrence and distribution of PPV in China but also provide detailed information about the genomic characteristics and evolutionary position of PPV isolates in China.