Comparative analysis of Panicum streak virus and Maize streak virus diversity, recombination patterns and phylogeography

Abstract

BackgroundPanicum streak virus (PanSV; Family Geminiviridae; Genus Mastrevirus) is a close relative of Maize streak virus (MSV), the most serious viral threat to maize production in Africa. PanSV and MSV have the same leafhopper vector species, largely overlapping natural host ranges and similar geographical distributions across Africa and its associated Indian Ocean Islands. Unlike MSV, however, PanSV has no known economic relevance.ResultsHere we report on 16 new PanSV full genome sequences sampled throughout Africa and use these together with others in public databases to reveal that PanSV and MSV populations in general share very similar patterns of genetic exchange and geographically structured diversity. A potentially important difference between the species, however, is that the movement of MSV strains throughout Africa is apparently less constrained than that of PanSV strains. Interestingly the MSV-A strain which causes maize streak disease is apparently the most mobile of all the PanSV and MSV strains investigated.ConclusionWe therefore hypothesize that the generally increased mobility of MSV relative to other closely related species such as PanSV, may have been an important evolutionary step in the eventual emergence of MSV-A as a serious agricultural pathogen.The GenBank accession numbers for the sequences reported in this paper are GQ415386-GQ415401

Global genetic diversity and geographical and host-species distribution of beak and feather disease virus isolates

“…BFDV-A (New Zealand specific, red-fronted parakeet), -C (predominantly South Africa, various species), -F (Thailand specific, various species), -G (Australia specific, rainbow lorikeet) and -L (South Africa specific, ring necked parakeets) were not detectably recombinant. Twelve of the 14 unique recombination events detected were within rep or in sequences encoding the N-terminal region of rep. A similar distribution of recombination break points has been found within begomoviruses and mastreviruses (Lefeuvre et al, 2007;Varsani et al, 2008Varsani et al, , 2009). Break-point density analysis revealed two globally significant recombination hotspots (local P values ,0.05, binomial probability), the first being along the entire intergenic region between the start of rep and cp, and the second being in the 39 portion of cp adjacent to the intergenic regions (Fig.…”

98% identical, 100% wrong: per cent nucleotide identity can lead plant virus epidemiology astray

“…Some pathogens move frequently and are repeatedly re-introduced to certain geographical areas. For instance, cassava mosaic begomoviruses have migrated from eastern Africa to western Africa at least twice (Ndunguru et al 2005), while the maizeadapted maize streak virus A has frequently moved around Africa (Varsani et al 2009). Although incomplete sampling of the diversity of plant viruses hampers definitive source tracking (Moury et al 2006), attempting to find the origin of novel viral sequences can become a useful standard in the field.…”

Reconstructing the History of Maize Streak Virus Strain A Dispersal To Reveal Diversification Hot Spots and Its Origin in Southern Africa

“…Although the movements most probably reflect the movement dynamics of the Cicadulina species and biotypes that are the most successful MSV-A vectors (1,45), differences between the movement dynamics of MSV-A (and particularly MSV-A 1 ) and those of other MSVs and other African mastrevirus species in general (all of which are transmitted by these same leafhopper species [70]) provide support for the hypothesis that there exists a specific virus-encoded determinant of increased MSV-A mobility (69,70). In this regard, it remains to be determined how meteorological factors, Cicadulina sp.…”

“…Although it is evident that over the last century the movement of some MSV-A subtypes across Africa has been far less constrained than the movements of either other MSV strains (69) or related African streak virus species (70), it is also apparent that the different MSV-A subtypes are not equally mobile. For example, whereas the MSV-A 1 subtype is found throughout Africa, the MSV-A 2 , -A 3 , -A 4 , and -A 6 subtypes have been found only in West Africa, East Africa, southern Africa, and the Indian Ocean island of La Réunion, respectively (39,50,69).…”