Molecular detection of watermelon mosaic virus associated with a serious mosaic disease on Cucurbita pepo L. in Shanxi, China

With continued expansion of Cucurbita pepo L. cultivation, viral diseases affecting the crop have become more serious in recent years, causing enormous losses in yield and quality. A virus sample was obtained from Wenshui in Shanxi province, China. Double-stranded RNA technology and sequence-independent amplification (SIA) were used to identify the virus that induced C. pepo L. mosaic disease. SIA and sequencing results showed the presence of watermelon mosaic virus (WMV) in diseased C. pepo L. leaves. The complete sequence of WMV from the Shanxi isolate (i.e., WMV-WS) was cloned and analyzed for further characterization. The genomic RNA of WMV-WS is 10,040 nucleotides in length and encodes a putative polyprotein of 3218 amino acids. Phylogenetic analysis indicate that all WMV isolates were divided into four groups and WMV-WS isolate belong to Group 4. Further analysis showed that these WMV isolates were not only to a certain degree related to the host, but also related to geographical origin of isolates. Our results provide information for a better understanding of the genetic diversity of WMV isolates infecting C. pepo L. in Shanxi, China.