Thladiantha Dubia Mosaic Virus: A Novel Potyvirus Infecting Manchurian Tubergourd (Thladiantha dubia) in Northeast China

Abstract

A new virus with flexuous, filamentous particles approximately 650 nm long was discovered in Manchurian tubergourd (Thladiantha dubia Bunge) leaves exhibiting severe mosaic symptoms. The whole genome sequence of the virus was determined by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The entire genome consisted of 10,112 nucleotides (nt) excluding the poly (A) tail, which shared the highest nucleotide sequence identity (73.8%) with that of papaya leaf distortion mosaic virus Hainan-DF isolate (PLDMV-Hainan-DF). A phylogenetic analysis showed that this virus clustered with PLDMV isolates in a subbranch within the potyviral clade. Of the 23 species of indicator plants tested, only potato and its original host were systemically infected by the virus tested upon mechanical inoculation. A field survey showed that the virus was widely distributed on T. dubia and potatoes in Northeast China. Moreover, this virus displayed a high degree of genetic variation as evaluated by the sequences of the coat protein (CP) gene. Based on these results, the name Thladiantha dubia mosaic virus (ThDMV) is proposed for this new potyvirus.