Polyploidy and Mutation in Arabidopsis

The effects of genetic mutations are influenced by genome structure.
Polyploids have more gene or allele copies than diploids, which results in
higher tolerance of recessive deleterious mutations. However, this benefit
may differ between autopolyploids and allopolyploids and between
neopolyploids and older polyploid lineages due to the effects of
hybridization and diploidization, respectively. To isolate these effects,
we measured the impacts of controlled mutagenesis on reproductive fitness
traits in closely related Arabidopsis diploids (A. thaliana),
autotetraploids (A. thaliana), and allotetraploids (A. suecica), including
both synthetic and natural polyploid lines. Overall, mutagenesis had the
largest negative impacts on seed production, while its impacts on
germination and survival were negligible. As expected, these effects were
much stronger in diploids than in polyploids. The differences between
autopolyploids, allopolyploids, and polyploids of different ages were
minor—cumulative reproductive fitness did not significantly differ between
the treatment and control groups for any polyploid line type. These
results suggest that hybridization and polyploid age have not impacted the
genomic redundancy of Arabidopsis polyploids enough to significantly alter
their aggregate response to mutation, although this effect may differ in
older polyploid lineages or in allopolyploids with different levels of
divergence between parental subgenomes.