Growth temperature alters the within-host competition of viral strains and differentially influences virus genetic variation

In this study we investigated how and what extent the variation of the host ecology (i.e., plant growth temperature) combined with the potential impact of mixed strain infections (i.e., within-host competitive viral interactions) may affect the evolutionary dynamics of viral populations. We inoculated tomato plants under single and mixed infection conditions with two infectious clones belonging to two strains of a plant RNA virus, pepino mosaic virus (PepMV), that in turn, were grown at two different temperatures (20 ºC and 30 ºC). After a long-term infection, the viral genome mutational analysis revealed variations in single-nucleotide polymorphisms that differed between both viral types and were determined to both factors. While type of infection (single and mixed) did not influence the averaged number of mutations for each viral population when plants were grown at low temperature conditions, both PepMV type populations displayed higher within-plant genetic variation, and exhibited a differential effect in mixed infections at high temperatures.