Experimental evidence indicating that mastreviruses probably did not co-diverge with their hosts

Abstract

Background: Despite the demonstration that geminiviruses, like many other single stranded DNA viruses, are evolving at rates similar to those of RNA viruses, a recent study has suggested that grass-infecting species in the genus Mastrevirus may have codiverged with their hosts over millions of years. This "co-divergence hypothesis" requires that long-term mastrevirus substitution rates be at least 100,000-fold lower than their basal mutation rates and 10,000-fold lower than their observable short-term substitution rates. The credibility of this hypothesis, therefore, hinges on the testable claim that negative selection during mastrevirus evolution is so potent that it effectively purges 99.999% of all mutations that occur.

Time - the emerging dimension of plant virus studies

“…The estimates produced by these methods agree with serial sampling studies, and are usually biologically sensible and supported by other evidence, much of which is recent and reliable. So, should we therefore conclude, as some have (Harkins et al, 2009;Holmes, 2009), that because the short-and long-term rates are so different, we must choose between them and discard the long-term rates as probably wrong? A corollary of this conclusion would be that we also accept that most singlestranded (ss)RNA viruses are modern and originated in the past few centuries or millennia at most.…”

High Variability and Rapid Evolution of a Nanovirus

“…In contrast, nucleotide substitution rates for ssDNA plant viruses have only recently been determined, either by evaluating geminivirus sequences available in databases (16,17) or by directly sequencing parts of or the entire genomes of individual members of virus populations (34,40,71). These studies indicated an evolution rate of 2.9 ϫ 10 Ϫ4 nucleotide substitutions/site/year for the tomato yellow leaf curl viruses (TYLCVs) over a period of almost 20 years (16), while those for DNA-A and DNA-B of East African cassava mosaic viruses (EACMVs) over about 5 years were 1.6 ϫ 10 Ϫ3 and 1.3 ϫ 10 Ϫ4 substitutions/site/year, respectively (17).…”

“…Viruses with a single-stranded DNA (ssDNA) genome depend for replication exclusively on host DNA polymerases yet exhibit a degree of sequence variability similar to that of RNA viruses (26,52,65,66). ssDNA plant virus variability and rapid sequence evolution were documented for geminiviruses with monopartite and bipartite genomes (7,16,17,34,40,42,68,71). The polymerases that replicate ssDNA plant virus genomes are not known; hence, their respective contributions to the sequence diversity of this virus group remain elusive.…”

Re-evaluation of the Mungbean [Vigna radiata (L.) Wilczek] Genotypes for Resistance to Mungbean Yellow Mosaic Virus (MYMV) under Screen-House Conditions

“…Among the various diseases of mungbean, MYMV causes significant yield losses and under severe conditions, the yield penalty may reach upto 80 to 100 per cent (Naimuddin, 2001 (Duffy et al, 2008;Harkins et al, 2009;Martin et al, 2011;Lima et al, 2012). Due to the large populations of whiteflies, and their ability to develop pesticide resistance, vector seclusion is not anideal way of fighting the spread and damage induced by MYMV.…”