Complete genome sequence of a novel bipartite begomovirus infecting the legume weed Macroptilium erythroloma.

The natural occurrence of mixed infections and large populations of the polyphagous vector (Bemisia tabaci) are the main factors associated with the intensification of the genetic flow among begomoviruses in Neotropical areas, contributing to the emergence of novel recombinants. Here, high-throughput sequencing and metagenomic analyses were employed to discover and characterize a novel recombinant bipartite begomovirus, tentatively named "macroptilium bright yellow interveinal virus" (MaBYIV) in the weed Macroptilium erythroloma (Fabaceae). Recombination signals were detected in MaBYIV, involving bean golden mosaic virus (BGMV) and tomato mottle leaf curl virus (ToMoLCV) genome components. All of the original MaBYIV-infected M. erythroloma plants were found to have mixed infections with BGMV. MaBYIV was transmitted to bean and soybean cultivars via B. tabaci MEAM 1, indicating that M. erythroloma may play a role as a year-round reservoir of a potential new viral pathogen of economically important legume crops.

Molecular Characterization of Hovenia Dulcis-Associated Virus 1 (HDaV1) and 2 (HDaV2): New Tentative Species within the Order Picornavirales.

In a systematic field survey for plant-infecting viruses, leaf tissues were collected from trees showing virus-like symptoms in Brazil. After viral enrichment, total RNA was extracted and sequenced using the MiSeq platform (Illumina). Two nearly full-length picorna-like genomes of 9534 and 8158 nucleotides were found associated with Hovenia dulcis (Rhamnaceae family). Based upon their genomic information, specific primers were synthetized and used in RT-PCR assays to identify plants hosting the viral sequences. The larger contig was tentatively named as Hovenia dulcis-associated virus 1 (HDaV1), and it exhibited low nucleotide and amino acid identities with Picornavirales species. The smaller contig was related to insect-associated members of the Dicistroviridae family but exhibited a distinct genome organization with three non-overlapping open reading frames (ORFs), and it was tentatively named as Hovenia dulcis-associated virus 2 (HDaV2). Phylogenetic analysis using the amino acid sequence of RNA-dependent RNA polymerase (RdRp) revealed that HDaV1 and HDaV2 clustered in distinct groups, and both viruses were tentatively assigned as new members of the order Picornavirales. HDaV2 was assigned as a novel species in the Dicistroviridae family. The 5' ends of both viruses are incomplete. In addition, a nucleotide composition analysis (NCA) revealed that HDaV1 and HDaV2 have similarities with invertebrate-infecting viruses, suggesting that the primary host(s) of these novel virus species remains to be discovered.