Experimental Adaptation of an RNA Virus Mimics Natural Evolution

Abstract

Identification of virulence determinants of viruses is of critical importance in virology.In search of such determinants, virologists traditionally utilize comparative genomics between a virulent and an avirulent virus strain and construct chimeras to map their locations. Subsequent comparison reveals sequence differences, and through analyses of site-directed mutants, key residues are identified. In the absence of a naturally occurring virulent strain, an avirulent strain can be functionally converted to a virulent variant via an experimental evolutionary approach. However, the concern remains whether experimentally evolved virulence determinants mimic those that have evolved naturally. To provide a direct comparison, we exploited a plant RNA virus, soybean mosaic virus (SMV), and its natural host, soybean. Through a serial in vivo passage experiment, the molecularly cloned genome of an avirulent SMV strain was converted to virulent variants on functionally immune soybean genotypes harboring resistance factor(s) from the complex Rsv1 locus. Several of the experimentally evolved virulence determinants were identical to those discovered through a comparative genomic approach with a naturally evolved virulent strain. Thus, our observations validate an experimental evolutionary approach to identify relevant virulence determinants of an RNA virus.

Quantitative trait loci from the host genetic background modulate the durability of a resistance gene: a rational basis for sustainable resistance breeding in plants

“…In tobacco, field observations revealing that va 2 -RB isolates were more frequent than va 0 -RB isolates (Verrier and Doroszewska, 2004) were confirmed by results from experimental evolution (Lacroix et al, 2011). Moreover, the distributions of RB mutations in viral genomes are usually similar in field and laboratory observations (Moury et al, 2004;Ayme et al, 2006;Hajimorad et al, 2010). However, for some resistance genes that proved very durable in the field, it may be difficult to generate RB variants by direct inoculation of avirulent strains.…”

The Potyviral P3 Protein Targets Eukaryotic Elongation Factor 1A to Promote the Unfolded Protein Response and Viral Pathogenesis

“…P3N-PIPO contributes to cell-to-cell movement of the virus in susceptible hosts (Chung et al, 2008;Wen and Hajimorad, 2010). HC-Pro, along with P3 and Cl, regulates SMV virulence Hajimorad et al, 2008;Seo et al, 2009;Zhang et al, 2009;Hajimorad et al, 2011;Seo et al, 2011;Chowda-Reddy et al, 2011;Wen et al, 2011). The precise biochemical function of SMV P3, and indeed the potyviral P3 protein in general, is largely uncharacterized due to the lack of structural or functional motifs in its sequence.…”

Recent Advances in In Planta Transient Expression and Silencing Systems for Soybean Using Viral Vectors

“…GUS expression was, however, still readily apparent in the eighth trifoliolate of infected plants (Wang et al 2006). SMV GUS, DsRed, and yellow fluorescent protein (YFP) have also been used to track virus infection and movement in studies of Rsv1-and Rsv3-mediated resistance to SMV (Zhang et al 2009a;Hajimorad et al 2011;Wen et al 2013; R.V.C.R., unpublished). Another strain of SMV, G7H, was modified in similar fashion to express reporter and other genes (Seo et al 2009).…”