Increasing growth temperature alters the within-host competition of viral strains and influences virus genetic variation
Alcaide et al., 2020
Alcaide et al., 2020
The emergence
of viral diseases in plant crops hamper the sustainability of food
production, and this may be boosted by global warming. Concurrently,
mixed viral infections are becoming common in plants, of which
epidemiology are unpredictable due to within-host virus-virus
interactions. However, the extent in which the combined effect of
variations in the abiotic components of the plant ecological niche
(e.g., temperature) and the prevalence of mixed infections (i.e.,
within-host interactions among viruses) affect the evolutionary dynamics
of viral populations is not well understood. Here, we explore the
interplay between ecological and evolutionary factors during viral
infections, and show that two individual strains of pepino mosaic virus
(PepMV) coexisted in a temperature-dependent continuum between neutral
and antagonistic interactions in tomato plants. After a long-term
infection, the mutational analysis of the evolved viral genomes revealed
strain-specific single-nucleotide polymorphisms that were modulated by
the interaction between the type of infection and temperature.
Mathematical modeling allowed us to asses a thermal reaction norm for
both strains, which indicated that viral replication rates were
increased along with increasing temperature in mixed infections, with a
remarkable strain-dependent effect. These results suggest that the
growth temperature is an ecological driver of virus-virus interactions,
with an effect on the genetic diversity of individual viruses
co-infecting a host. This research provides insights into the effect
that climate change will have on the evolutionary dynamics of viral
populations.
(A) What is the effect of mixed viral infections on the fitness and genetic diversity of viral populations within a host? (B and C) Barplots exhibiting the viral load (RNA molecules / ng RNA total) of each PepMV (CH2 and EU) strain in tomato plants grown at 20 ºC and 30 ºC under single (black) and mixed infection (grey) condition. Viral accumulation was inferred by absolute quantification using RT-qPCR after 7 dpi (B) and60 dpi (C).
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