Polyploidy and mutation in Arabidopsis

Abstract

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.

Formation of Different Polyploids Through Disrupting Meiotic Crossover Frequencies Based on cntd1 Knockout in Zebrafish

“…In comparison to diploid organisms, tetraploids confer a significant advantage in terms of gene redundancy, acting as a protective shield against the deleterious effects of mutations by masking recessive alleles through dominant WT alleles. During the gametophytic stage, the vulnerability of haploid gametes from diploids to detrimental loss-of-function mutations is mitigated by diploid gametes from tetraploids, which can camouflage the impact of deleterious recessive alleles with additional wild-type alleles ( Immler 2019 ; Spoelhof et al 2021 ). Furthermore, at the zygotic stage, polyploidy reduces the occurrence of homozygous recessive alleles ( Stadler 1929 ; Mable and Otto 2001 ).…”

Phenotypic trait variation in the North American Tragopogon allopolyploid complex

“…In some polyploids, increased mature seed size can produce a trade‐off resulting in an overall reduction of seed production and reproductive output (Porturas et al, 2019; Spoelhof et al, 2021). The polyploids in this study all produced fewer mature seeds per inflorescence than diploid T. dubius , but similar or greater amounts than T. pratensis and T. porrifolius .…”

Scaling the fitness effects of mutations with respect to differentially adaptedArabidopsis thalianaaccessions under natural conditions

“…Our results are also consistent with several studies that have quantified mutation effects on A. thaliana performance in laboratory conditions, where the mutagen is a single T-DNA insert (Rutter et al 2017; Murren et al 2019). Spoelhof et al (2021) found EMS induced mutations in A. thaliana to have uniformly deleterious effects on performance. However, they used a higher dosage and did not transfer the mutations through several generations (as we did).…”