Patterns and Processes of Diploidization in Land Plants

Abstract

Most land plants are now known to be ancient polyploids that have rediploidized. Diploidization involves many changes in genome organization that ultimately restore bivalent chromosome pairing, disomic inheritance, and resolve dosage and other issues caused by genome duplication. In this review, we discuss the nature of polyploidy and its impact on chromosome pairing behavior. We also provide an overview of two major and largely independent processes of diploidization: cytological diploidization and genic diploidization/fractionation. Finally, we compare variation in gene fractionation across land plants and highlight the differences in diploidization between plants and animals. Altogether, we demonstrate recent advancements in our understanding of variation in the patterns and processes of diploidization in land plants and provide a road map for future research to unlock the mysteries of diploidization and eukaryotic genome evolution. Expected final online publication date for the Annual Review of Plant Biology, Volume 72 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Polyploidy and mutation in Arabidopsis

“…Diploidization in polyploids is a complex process, including cytological and genetic changes that occur over different and variable time scales (Ma & Gustafson, 2005; Li et al. 2021). In tetraploid A. thaliana and A. suecica , cytological changes such as chromosomal gains, losses, or rearrangements and the evolution of stable meiotic pairing can occur quickly after WGD, even within a few generations (Santos et al.…”

“…Genetic changes such as gene loss and genomic fractionation continue to occur over longer time scales and may proceed at different rates in different lineages (Li et al. 2021). Although allotetraploid A. suecica formed only ∼20,000 years ago (Novikova et al.…”

“…2010; Soltis et al. 2015; Wendel 2015; Li et al., 2021), but these processes will impact autopolyploids and allopolyploids differently because of differences in inheritance and genome structure (reviewed in Parisod et al. 2010; Wendel 2015; Spoelhof et al.…”

Interfered Chromosome Pairing Promotes Meiosis Instability of Autotetraploid Arabidopsis by High Temperatures

“…WGD is a conserved phenomenon that contributes to genomic diversity and speciation in higher plants (Comai, 2005; Dubcovsky and Dvorak, 2007; te Beest et al, 2012; Ren et al, 2018; Van de Peer et al, 2020; Li et al, 2021). Additional copies of chromosomes, however, also increase the complexity and challenge for homolog pairing and synapse which eventually harms balanced chromosome segregation at later meiosis stages (Yant et al, 2013; Lloyd and Bomblies, 2016; Svačina et al, 2020; Li et al, 2021). In this study, we found that synthesized autotetraploid Col-0 yields a low but consistently-detectable rate of aberrant meiotic products under normal temperature conditions (Fig.…”

Inference of polyploid origin and inheritance mode from population genomic data

“…Polyploid organisms have more than two sets of chromosomes as a result of whole-genome duplication (WGD) and are typically described as belonging to one of two categories: auto polyploids being formed by WGD within a single lineage, and allo polyploids in the case of hybridization between divergent lineages. Though observations of chromosome behaviour during meiosis were initially the only information available for assigning polyploid “types” (1) , we now have to distinguish between this original cytogenetic (genetic according to Li et al (2) ) classification of auto- or allo-polyploidy, and the now common phylogenetic classification (taxonomic according to Li et al, we prefer the term phylogenetic as evolutionary relationships are not always reflected by taxonomy). Furthermore, there is a distinction between inheritance mode (allelic segregation) in polyploids and their classification by either cytogenetic or phylogenetic means.…”