A novel monopartite begomovirus and satellites associated with yellow mosaic disease of Sida spp. in India.

Begomoviruses (family Geminiviridae) cause severe diseases in many economically important crops and non-cultivated plants in the warmer regions of the world. Non-cultivated weeds have been reported to act as natural virus reservoirs. In January 2016, Sida plants with yellow mosaic symptoms were found at the edge of an agricultural field in Gujarat, India. Sequence analysis of the viral genomic components cloned from a diseased Sida plant indicated the presence of a distinct monopartite begomovirus (proposed as sida yellow mosaic Gujarat virus) along with a betasatellite (ludwigia leaf distortion betasatellite) and an alphasatellite (malvastrum yellow mosaic alphasatellite). Our results emphasize that this weed may harbor a begomovirus-alphasatellite-betasatellite complex. This host serves as a potential source of virus inoculum, which can be transmitted by whiteflies to other cultivated crops.

Complete sequence of a new bipartite begomovirus infecting Sida sp. in Northeastern Brazil.

In Brazil, non-cultivated plants, especially weeds, are infected with a diversity of begomoviruses and often show striking golden mosaic symptoms. In the present study, leaves showing these symptoms were collected from Sida sp. plants in Guadalupe, Piaui State, Northeastern Brazil, in 2015 and 2016. PCR tests with degenerate primers revealed the presence of begomovirus DNA-A and DNA-B components. Restriction enzyme digestion of rolling circle-amplified DNA revealed fragments totaling ~5.2 kb, indicating infection by a bipartite begomovirus. The DNA-A and DNA-B components have a genome organization typical of New World (NW) bipartite begomoviruses and a common region of 220 nucleotides (nt) with 96% identity, indicating these are cognate components. Comparisons performed with the DNA-A sequence revealed the highest nt sequence identity (84%) with that of sida angular mosaic virus (SiAMV), whereas those performed with the DNA-B sequence revealed highest identity (77%) with that of sida chlorotic vein virus (SiCVV). In phylogenetic analyses, the DNA-A sequence was placed in a strongly supported clade with SiAMV and SiCVV from Piaui, whereas the DNA-B sequence was placed in a clade with SiCVV and corchorus mottle virus. Based on the current ICTV criteria for the demarcation of begomovirus species (<91% nt sequence identity for the DNA-A component), this is a member of a new species for which the name "Sida yellow golden mosaic virus" is proposed.

Characterization of sida golden mottle virus isolated from Sida santaremensis Monteiro in Florida.

The genome of sida golden mottle virus (SiGMoV) (GU997691 and GU997692) isolated from Sida santaremensis Monteiro in Manatee County, Florida, was sequenced and characterized. SiGMoV was determined to be a bipartite virus belonging to the genus Begomovirus with a genome organization typical of the New World viruses in the genus. SiGMoV DNA-A had the highest identity scores (89%) and showed the closest evolutionary relationships to sida golden mosaic Buckup virus (SiGMBuV) (JX162591 and HQ008338). However, SiGMoV DNA-B had the highest identity scores (93%) and showed the closest evolutionary relationship to corchorus yellow spot virus (DQ875869), SiGMBuV (JX162592) and sida golden mosaic Florida virus (SiGMFlV) (HE806443). There was extensive recombination in the SiGMoV DNA-A and much less in DNA-B. Full-length clones of SiGMoV were infectious and were able to infect and cause symptoms in several plant species.