Between sexual and apomictic: unexpectedly variable sporogenesis and production of viable polyhaploids in the pentaploid fern of the<i>Dryopteris affinis</i>agg. (Dryopteridaceae)

Ekrt, Libor; Koutecký, Petr

doi:10.1093/aob/mcv152

Cited by 28 publications

(31 citation statements)

References 38 publications

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“…Although polyploidization is increasingly recognized as an important factor in the diversification of plant sexual systems (Pannell et al 2004;Obbard et al 2006;Ashman et al 2013;Ludwig et al 2013;Blank et al 2014;Ekrt and Koutecký 2016), homoploid hybridization between sexual systems has seldom been considered as a mechanism promoting variation in sex ratios and transitions among sexual systems (but see Barr 2004;Pannell et al 2008). We have demonstrated that the majority of subdioecious populations of S. latifolia examined show evidence of genetic admixture between monoecious and dioecious populations.…”

Section: Hybridization and Sexual System Diversitymentioning

confidence: 84%

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The role of hybridization in the evolution of sexual system diversity in a clonal, aquatic plant

Yakimowski

Barrett

2016

Evolution

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The stable coexistence within populations of females, males, and hermaphrodites (subdioecy) is enigmatic because theoretical models indicate that maintenance of this sexual system involves highly restricted conditions. Subdioecy is more commonly interpreted as a transitory stage along the gynodioecious pathway from hermaphroditism to dioecy. The widespread, North American, aquatic plant Sagittaria latifolia is largely composed of monoecious or dioecious populations; however, subdioecious populations with high frequencies of hermaphrodites (mean frequency = 0.50) characterize the northern range boundary of dioecy in eastern North America. We investigated two hypotheses for the origin of subdioecy in this region. Using polymorphic microsatellite loci, we evaluated whether subdioecy arises through selection on standing genetic variation for male sex inconstancy in dioecious populations, or results from hybridization between monoecious and dioecious populations. We found evidence for both pathways to subdioecy, although hybridization was the more common mechanism, with genetic evidence of admixture in nine of 14 subdioecious populations examined. Hybridization has also played a role in the origin of androdioecious populations in S. latifolia, a mechanism not often considered in the evolution of this rare sexual system. Our study demonstrates how hybridization has the potential to play a role in the diversification of plant sexual systems.

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Section: Hybridization and Sexual System Diversitymentioning

confidence: 84%

“…; Blank et al. ; Ekrt and Koutecký ), homoploid hybridization between sexual systems has seldom been considered as a mechanism promoting variation in sex ratios and transitions among sexual systems (but see Barr ; Pannell et al. ).…”

Section: Discussionmentioning

confidence: 99%

The role of hybridization in the evolution of sexual system diversity in a clonal, aquatic plant

Yakimowski

Barrett

2016

Evolution

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“…By measuring the fluorescence emission of a large number of suspended nuclei, flow cytometry provides an estimate of genome size in an individual plant or tissue relative to a reference standard of known size (Doležel & Bartoš, ). In the past decade, flow cytometry, often in conjunction with molecular or morphological data, has become a regularly adopted tool for identifying allopolyploids in many fern genera (e.g., Asplenium : Ekrt & Štech, ; Chang et al, ; Botrychium : Dauphin et al, ; Dryopteris : Ekrt et al, , ; Ekrt & Koutecký, ; Equisetum : Bennert et al, ; Polypodium : Bureš et al, ; Pteridium : Wolf et al, ; Vandenboschia : Ebihara et al, ), but it has yet to be specifically employed to assess questions of genome size evolution in hybrid ferns.…”

Section: Transcriptomic Genetic and Genomic Consequences Of Hybridimentioning

confidence: 99%

“…1D;Stebbins, 1950;Sybenga, 1996). Notably, some allopolyploid species resulting from crosses between sexual and apomictic progenitors (via the production of viable sperm by the apomicts; Manton, 1950;Lovis, 1977), despite inheriting an apomictic mode of reproduction, produce relatively low numbers of viable spores (approximately 5-10%; Manton, 1950;Morzenti, 1967;Mulligan et al, 1972; but see Walker, 1962 for spore viability as high 40%), sometimes of mixed ploidy in the same individual or even within a sporangium (Ekrt & Kouteck y, 2016).…”

Section: Allopolyploidsmentioning

confidence: 99%

Genetic and genomic aspects of hybridization in ferns

Sigel

2016

J of Sytematics Evolution

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The morphological and ecological intermediacy of hybrid taxa has long interested and challenged fern biologists, resulting in numerous systematic contributions focused on disentangling relationships within reticulate species complexes. From a genetic perspective, hybrid ferns are especially interesting because they represent the union of divergent parental genomes in unique evolutionary entities. This review summarizes advances in our knowledge of the genetic and genomic aspects of hybridization in ferns from the mid-20th century to the present. The different organismal products of hybridization, evolutionary aspects of additive and non-additive gene expression in allopolyploids, genetic and genomic mechanisms leading to gene silencing and loss, the roles of multiple origins and introgression for imparting genetic variation to hybrid fern taxa and their progenitors, and the utility of allopolyploid ferns to investigate mechanisms of genome evolution in the homosporous ferns are discussed. Comparisons are made to other plant lineages and important future research directions are highlighted, with the goal of stimulating additional research on hybrid ferns.

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“…For example, one trend that has emerged is the tendency for apomictic individuals to attempt multiple meiotic pathways (Sigel et al, 2011;Hern andez et al, 2015;Ekrt & Koutecky, 2016). In their elegant follow-up to Manton's work in Dryopteris (1950), Ekrt & Koutecky (2016) observed variously abortive, haploid, and diploid spores, among and even within individual sporangia on a single plant. Using flow cytometry, they also documented viable polyhaploid (2.5x) gametophytes derived through apomixis from a 5x parent.…”

Section: Apomixis In Ferns Since 2004mentioning

confidence: 99%

A current perspective on apomixis in ferns

Grusz

2016

J of Sytematics Evolution

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This review provides a synopsis of apogamous reproduction in ferns and highlights important progress made in the study of fern apomixis over the past decade. First, a summary of the apomictic fern life cycle is provided, distinguishing between two pathways to diploid spore production that have been documented in apomictic ferns (premeiotic endomitosis and meiotic first division restitution) and briefly discussing the evolutionary implications of each. Next, recent trends in fern apomixis research are highlighted, exposing a shift in focus from the observation and characterization of apomixis in ferns to more integrated studies of the evolutionary and ecological implications of this reproductive mode. Peer-reviewed contributions from the past decade are then summarized, spanning the identification of new apomictic lineages through to the developmental, phylogenetic, and population genetic insights that have been made in studies of fern apomixis during that time. Gaps in our understanding of fern apomixis are also discussed, including the extent and implications of recombinant apomixis in ferns, the possible reversibility of reproductive mode (from apomictic to sexual) in ferns, and the genomic causes and consequences of apomixis in seed A u t h o r M a n u s c r i p t A u t h o r M a n u s c r i p t A u t h o r M a n u s c r i p tGrusz, 2 of 23 free vascular plants. Finally, future directions for fern apomixis research are discussed in the context of modern technological advances and recent insights from studies of apomixis in other groups.Keywords: apogamy, evolution of sex, meiosis, pteridophytes.A u t h o r M a n u s c r i p t A u t h o r M a n u s c r i p t A u t h o r M a n u s c r i p t Grusz, 3 of 23 "…apomixis is an escape from sterility, but it is an escape into a blind alley of evolution…" -Darlington, 1939A renaissance is underway in fern biology, propelled, in part, by technological advances being embraced by a growing research community. In particular, modern, cost-effective tools are enabling new inquiries into the unique fern life cycle, which alternates between independent, free-living sporophyte and gametophyte generations (Haufler et al., 2016). Among the many aspects of fern reproduction that are being examined in light of new approaches-and an improved understanding of fern evolution as a whole-is their propensity for apogamous reproduction (i.e., apomixis). This form of asexual reproduction (by spore or seed) is more common in ferns than in any other group of vascular plants. Nearly 10% of the ferns for which reproductive mode has been determined exhibit apomixis (Walker, 1985; Liu et al., 2012), compared to less than 1% in flowering plants (Bicknell & Koltunow, 2004; Becks & Alavi, 2015). Given that data on reproductive mode is lacking for the vast majority of ferns, this relative contribution of apomicts to fern diversity may well be an underestimate (Liu et al., 2012). The elevated frequency and distinctive meiotic characteristics of apomixis in ferns, which are elaborated upon bel...

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Between sexual and apomictic: unexpectedly variable sporogenesis and production of viable polyhaploids in the pentaploid fern of theDryopteris affinisagg. (Dryopteridaceae)

Cited by 28 publications

References 38 publications

The role of hybridization in the evolution of sexual system diversity in a clonal, aquatic plant

The role of hybridization in the evolution of sexual system diversity in a clonal, aquatic plant

Genetic and genomic aspects of hybridization in ferns

A current perspective on apomixis in ferns

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