Discovery of the first maize-infecting mastrevirus in the Americas using a vector-enabled metagenomics approach.

The genus Mastrevirus (family Geminiviridae) is composed of single-stranded DNA viruses that infect mono- and dicotyledonous plants and are transmitted by leafhoppers. In South America, there have been only two previous reports of mastreviruses, both identified in sweet potatoes (from Peru and Uruguay). As part of a general viral surveillance program, we used a vector-enabled metagenomics (VEM) approach and sampled leafhoppers (Dalbulus maidis) in Itumbiara (State of Goiás), Brazil. High-throughput sequencing of viral DNA purified from the leafhopper sample revealed mastrevirus-like contigs. Using a set of abutting primers, a 2746-nt circular genome was recovered. The circular genome has a typical mastrevirus genome organization and shares <63% pairwise identity with other mastrevirus isolates from around the world. Therefore, the new mastrevirus was tentatively named "maize striate mosaic virus". Seventeen maize leaf samples were collected in the same field as the leafhoppers, and ten samples were found to be positive for this mastrevirus. Furthermore, the ten genomes recovered from the maize samples share >99% pairwise identity with the one from the leafhopper. This is the first report of a maize-infecting mastrevirus in the Americas, the first identified in a non-vegetatively propagated mastrevirus host in South America, and the first mastrevirus to be identified in Brazil.