Identification of Potato mop-top virus (PMTV) in potatoes in China

Abstract

Potato tubers exhibiting necrotic rings/arcs were found in a winter potato crop ‘Favorita’ in the subtropical area Huidong county, Guangdong province, China, in 2012. When the symptomatic tubers were cut crosswise, light to dark brown necrotic arcs were observed in the tuber flesh. A mini-survey of the crop found 8% symptomatic tubers in an area of 10 meters2. To reveal the causal agent of the disease, reverse transcription–polymerase chain reactions (RT-PCR) targeting 9 common potato viruses including those viruses (e.g, Potato mop-top virus (PMTV), Tobacco rattle virus, Tomato spotted wilt virus, and Potato virus Y tuber necrosis strain) known to be capable of induction of tuber necrosis, were carried out. Except for PMTV, no other viruses were detected. Sequencing of the 460 bp amplicon revealed that the fragment exhibited a 99-100% sequence identify with most PMTV coat protein sequences deposited in GenBank, which was confirmed by a further phylogenetic analysis. Enzyme linked immunosorbent assay with PMTV antibody on the symptomatic tubers was also carried out, and a positive reading was observed. Together, these results demonstrate that PMTV was the causal agent for the spraing disease in potatoes in the winter crop in Guangdong. To our knowledge, this is the first report of PMTV in Guangdong province, China, and the first scientific confirmation of PMTV in China.