Forced recombination between distinct strains of Maize streak virus

Recombination between divergent virus genomes is believed to be a major mechanism for generation of novel virus genotypes. We have examined the recombination process in geminiviruses by forcing recombination between two distinct isolates of Maize streak virus (MSV), MSV-Kom and MSV-Set. Heterodimeric agroinfectious constructs containing tandemly cloned mixtures of complete or partial MSV-Set and MSV-Kom genomes were used to simulate a circular dimeric form similar to that which would be expected to occur following a single intermolecular crossing-over event between MSV-Set and MSV-Kom replicative form DNAs at the long intergenic region (LIR)–movement protein gene (MP) interface. We isolated, analysed and biologically characterized many of the recombinant MSV genomes that were generated from the constructs in planta. Apart from having the same simulated breakpoint at the LIR–MP interface, all the genomes examined had a second breakpoint that had been generated through either intramolecular homologous recombination or a replicational release mechanism. The pathogenicities of six predominantly MSV-Kom-like recombinants were tested in maize. While all were capable of producing a symptomatic infection in this host, none was more virulent than MSV-Kom and only two were more virulent than MSV-Set. The two most virulent recombinants were leafhopper transmitted to a range of differentially MSV-resistant maize, wheat and barley genotypes and both were found to have unique biological properties.

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Successful application of FTA® Classic Card technology and use of bacteriophage ϕ29 DNA polymerase for large-scale field sampling and cloning of complete maize streak virus genomes

Journal of Virological Methods ◽

10.1016/j.jviromet.2006.11.004 ◽

2007 ◽

Vol 140 (1-2) ◽

pp. 100-105 ◽

Cited By ~ 52

Author(s):

Betty E. Owor ◽

Dionne N. Shepherd ◽

Nigel J. Taylor ◽

Richard Edema ◽

Adérito L. Monjane ◽

...

Keyword(s):

Dna Polymerase ◽

Large Scale ◽

Maize Streak Virus ◽

Streak Virus ◽

Field Sampling ◽

Scale Field ◽

Large Scale Field ◽

Virus Genomes

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Extensive Recombination-Induced Disruption of Genetic Interactions Is Highly Deleterious but Can Be Partially Reversed by Small Numbers of Secondary Recombination Events

Journal of Virology ◽

10.1128/jvi.00709-14 ◽

2014 ◽

Vol 88 (14) ◽

pp. 7843-7851 ◽

Cited By ~ 12

Author(s):

Adérito L. Monjane ◽

Darren P. Martin ◽

Francisco Lakay ◽

Brejnev M. Muhire ◽

Daniel Pande ◽

...

Keyword(s):

Genetic Material ◽

Evolutionary Process ◽

Virus Genome ◽

Maize Streak Virus ◽

Genetic Interactions ◽

Streak Virus ◽

Fitness Costs ◽

A Genome ◽

Virus Genomes ◽

Recombination Breakpoints

ABSTRACTAlthough homologous recombination can potentially provide viruses with vastly more evolutionary options than are available through mutation alone, there are considerable limits on the adaptive potential of this important evolutionary process. Primary among these is the disruption of favorable coevolved genetic interactions that can occur following the transfer of foreign genetic material into a genome. Although the fitness costs of such disruptions can be severe, in some cases they can be rapidly recouped by either compensatory mutations or secondary recombination events. Here, we used a maize streak virus (MSV) experimental model to explore both the extremes of recombination-induced genetic disruption and the capacity of secondary recombination to adaptively reverse almost lethal recombination events. Starting with two naturally occurring parental viruses, we synthesized two of the most extreme conceivable MSV chimeras, each effectively carrying 182 recombination breakpoints and containing thorough reciprocal mixtures of parental polymorphisms. Although both chimeras were severely defective and apparently noninfectious, neither had individual movement-, encapsidation-, or replication-associated genome regions that were on their own “lethally recombinant.” Surprisingly, mixed inoculations of the chimeras yielded symptomatic infections with viruses with secondary recombination events. These recombinants had only 2 to 6 breakpoints, had predominantly inherited the least defective of the chimeric parental genome fragments, and were obviously far more fit than their synthetic parents. It is clearly evident, therefore, that even when recombinationally disrupted virus genomes have extremely low fitness and there are no easily accessible routes to full recovery, small numbers of secondary recombination events can still yield tremendous fitness gains.IMPORTANCERecombination between viruses can generate strains with enhanced pathological properties but also runs the risk of producing hybrid genomes with decreased fitness due to the disruption of favorable genetic interactions. Using two synthetic maize streak virus genome chimeras containing alternating genome segments derived from two natural viral strains, we examined both the fitness costs of extreme degrees of recombination (both chimeras had 182 recombination breakpoints) and the capacity of secondary recombination events to recoup these costs. After the severely defective chimeras were introduced together into a suitable host, viruses with between 1 and 3 secondary recombination events arose, which had greatly increased replication and infective capacities. This indicates that even in extreme cases where recombination-induced genetic disruptions are almost lethal, and 91 consecutive secondary recombination events would be required to reconstitute either one of the parental viruses, moderate degrees of fitness recovery can be achieved through relatively small numbers of secondary recombination events.

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