Metagenomic Analysis of RNA Viruses in Watermelon

Watermelon is one of the most consumed cucurbits worldwide. Its production, nevertheless, is threatened by different pathogens that compromise the development of plants and, consequently, fruits. Here, plants showing typical virus-like symptoms were collected in the Tocantins State, Brazil. Aiming for the identification of viruses, viral RNA was sequenced by Illumina. Four virus genomes were sequenced and assembled, corresponding to isolates of Papaya ringspot virus (PRSV) and Zucchini Yellow Mosaic Virus (ZYMV) from the family Potyviridae, Groundnut ringspot virus (GRSV) from the family Bunyaviridae, and Citrullus lanatus partitivirus (CiLPV) from family Partitiviridae. Although these viruses have been previously reported infecting watermelon, we have sequenced the first complete genome of GRSV and the first complete genome of a ZYMV isolate from Brazil. Symptomatic watermelon leaves from the field were also used as inoculation for virus mechanical transmission to indicative plants. Despite co-infecting watermelon plants in the field, only the potyviruses were mechanically transmitted to indicative plants, in which ZYMV presented the broadest host range.