Deletion and recombination events between the DNA-A and DNA-B components of Indian cassava-infecting geminiviruses generate defective molecules in Nicotiana benthamiana

Patil, Basavaprabhu L.; Dutt, N.; Briddon, R. W.; Bull, Simon E.; Rothenstein, Dirk; Borah, Bibha Chetia; Dasgupta, Indranil; Stanley, John; Jeske, Holger

doi:10.1016/j.virusres.2006.10.003

Cited by 32 publications

(25 citation statements)

References 40 publications

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“…The DI DNA in this case was ACMV DNA B component from which large segments had been deleted, including BV1, but which retained the CR and parts of BC1 (Stanley and Townsend, 1985). Similar results were subsequently reported for corresponding DIs from SLCMV (Patil et al, 2007). The transgenic plants displayed symptom amelioration characterized by increased levels of subgenomic DNA and a comparable reduction in the level of genomic DNA.…”

Section: Engineered Resistance To Cmgssupporting

confidence: 88%

The Search for Resistance to Cassava Mosaic Geminiviruses: How Much We Have Accomplished, and What Lies Ahead

Fondong

2017

Front. Plant Sci.

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The cassava mosaic disease (CMD), which occurs in all cassava growing regions of Africa and the Indian subcontinent, is caused by cassava mosaic geminiviruses (CMGs). CMGs are considered to be the most damaging vector-borne plant pathogens. So far, the most successful approach used to control these viruses has been the transfer of a polygenic recessive resistance locus, designated CMD1, from wild cassava to cassava cultivars. Further progress in harnessing natural resistance to contain CMGs has come from the discovery of the dominant monogenic resistance locus, CMD2, in some West African cassava cultivars. CMD2 has been combined with CMD1 through genetic crosses. Because of the limitations of the cassava breeding approach, especially with regard to time required to produce a variety and the loss of preferred agronomic attributes, efforts have been directed toward the deployment of genetic engineering approaches. Most of these approaches have been centered on RNA silencing strategies, developed mainly in the model plant Nicotiana benthamiana. Early RNA silencing platforms assessed for CMG resistance have been use of viral genes for co-suppression, antisense suppression or for hairpin RNAs-mediated gene silencing. Here, progress and challenges in the deployment of these approaches in the control of CMGs are discussed. Novel functional genomics approaches with potential to overcome some of the drawbacks of the current strategies are also discussed.

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Section: Engineered Resistance To Cmgssupporting

confidence: 88%

The Search for Resistance to Cassava Mosaic Geminiviruses: How Much We Have Accomplished, and What Lies Ahead

Fondong

2017

Front. Plant Sci.

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“…Examples in which recombination between viral and subviral components may aggravate disease symptoms can be found among the single-stranded DNA plant viruses of the family Geminiviridae (50). Recombination between DNA satellites plays a role in the evolution of these viruses (2), but deletions and recombination occurring at repetitive sequences within or between the DNA-A and DNA-B components of the begomoviruses lead to defective DNA components which in turn lead to a modification in the disease symptoms (41). The genomes of nanoviruses in plants consist of multiple circular single strands of DNA, the majority of which encode one gene each (57).…”

Section: Discussionmentioning

confidence: 99%

In Vivo and In Vitro Intragenomic Rearrangement of TT Viruses

Leppik

Gunst

Lehtinen

et al. 2007

J Virol

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The in vitro replication of the Torque teno virus (TT virus) tth8 full-length genome and particle formation in a Hodgkin's lymphoma-derived cell line after transfection with cloned viral DNA were demonstrated. Analyses of the transcription patterns of tth8 and tth7 TT virus isolates in a number of lymphoma and T-cell leukemia cell lines indicated differential additional splicing events and intragenomic rearrangement generating open reading frames which could not be deducted from the genomic sequence. We also demonstrated the presence of rearranged TT virus genomes in vivo in sera taken from pregnant mothers whose children later developed childhood leukemia, as well as sera from control mothers. Control experiments using religated cloned genomic tth8 DNA mixed with cellular DNA did not result in such subviral molecules. These subviral isolates ranged from 172 bp to full-length TT virus genomes. Possible in vivo selection for specific rearranged molecules was indicated by the presence of one isolate (561 bp) in 11 serum samples. It remains to be clarified whether selected rearranged subviral components resulting from specific TT virus types may contribute to the initiation of disease. These data demonstrate new features of TT viruses suggesting possible similarities to plant viruses of the family Geminiviridae, as well as raise questions about the documented plurality and diversity of anelloviruses.

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“…These molecules are known as defective interfering (di) DNAs due to their capacity to interfere with virus infection, reducing virus DNA levels and symptom severity [23]. Surprisingly the diDNAs associated with bipartite begomoviruses are derived almost exclusively from the DNA-B component.…”

Section: Introductionmentioning

confidence: 99%

Distinct evolutionary histories of the DNA-A and DNA-B components of bipartite begomoviruses

et al. 2010

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BackgroundViruses of the genus Begomovirus (family Geminiviridae) have genomes consisting of either one or two genomic components. The component of bipartite begomoviruses known as DNA-A is homologous to the genomes of all geminiviruses and encodes proteins required for replication, control of gene expression, overcoming host defenses, encapsidation and insect transmission. The second component, referred to as DNA-B, encodes two proteins with functions in intra- and intercellular movement in host plants. The origin of the DNA-B component remains unclear. The study described here was initiated to investigate the relationship between the DNA-A and DNA-B components of bipartite begomoviruses with a view to unraveling their evolutionary histories and providing information on the possible origin of the DNA-B component.ResultsComparative phylogenetic and exhaustive pairwise sequence comparison of all DNA-A and DNA-B components of begomoviruses demonstrates that the two molecules have very distinct molecular evolutionary histories and likely are under very different evolutionary pressures. The analysis highlights that component exchange has played a far greater role in diversification of begomoviruses than previously suspected, although there are distinct differences in the apparent ability of different groups of viruses to utilize this "sexual" mechanism of genetic exchange. Additionally we explore the hypothesis that DNA-B originated as a satellite that was captured by the monopartite progenitor of all extant bipartite begomoviruses and subsequently evolved to become the integral (essential) genome component that we recognize today. The situation with present-day satellites associated with begomoviruses provides some clues to the processes and selection pressures that may have led to the "domestication" of a wild progenitor of the DNA-B component.ConclusionsThe analysis has highlighted the greater genetic variation of DNA-B components, in comparison to the DNA-A components, and that component exchange is more widespread than previously demonstrated and confined to viruses from the Old World. Although the vast majority of New World and some Old World begomoviruses show near perfect co-evolution of the DNA-A and DNA-B components, this is not the case for the majority of Old World viruses. Genetic differences between Old and New World begomoviruses and the cultivation of exotic crops in the Old World are likely factors that have led to this dichotomy.

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Deletion and recombination events between the DNA-A and DNA-B components of Indian cassava-infecting geminiviruses generate defective molecules in Nicotiana benthamiana

Cited by 32 publications

References 40 publications

The Search for Resistance to Cassava Mosaic Geminiviruses: How Much We Have Accomplished, and What Lies Ahead

The Search for Resistance to Cassava Mosaic Geminiviruses: How Much We Have Accomplished, and What Lies Ahead

In Vivo and In Vitro Intragenomic Rearrangement of TT Viruses

Distinct evolutionary histories of the DNA-A and DNA-B components of bipartite begomoviruses

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