Format

Send to

Choose Destination
Proc Natl Acad Sci U S A. 2017 Feb 7;114(6):E1027-E1035. doi: 10.1073/pnas.1615123114. Epub 2017 Jan 23.

Endosperm-based hybridization barriers explain the pattern of gene flow between Arabidopsis lyrata and Arabidopsis arenosa in Central Europe.

Author information

1
Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden.
2
Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0313 Oslo, Norway.
3
Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, 0313 Oslo, Norway.
4
Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0313 Oslo, Norway; paul.grini@ibv.uio.no claudia.kohler@slu.se.
5
Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden; paul.grini@ibv.uio.no claudia.kohler@slu.se.

Abstract

Based on the biological species concept, two species are considered distinct if reproductive barriers prevent gene flow between them. In Central Europe, the diploid species Arabidopsis lyrata and Arabidopsis arenosa are genetically isolated, thus fitting this concept as "good species." Nonetheless, interspecific gene flow involving their tetraploid forms has been described. The reasons for this ploidy-dependent reproductive isolation remain unknown. Here, we show that hybridization between diploid A. lyrata and A. arenosa causes mainly inviable seed formation, revealing a strong postzygotic reproductive barrier separating these two species. Although viability of hybrid seeds was impaired in both directions of hybridization, the cause for seed arrest differed. Hybridization of A. lyrata seed parents with A. arenosa pollen donors resulted in failure of endosperm cellularization, whereas the endosperm of reciprocal hybrids cellularized precociously. Endosperm cellularization failure in both hybridization directions is likely causal for the embryo arrest. Importantly, natural tetraploid A. lyrata was able to form viable hybrid seeds with diploid and tetraploid A. arenosa, associated with the reestablishment of normal endosperm cellularization. Conversely, the defects of hybrid seeds between tetraploid A. arenosa and diploid A. lyrata were aggravated. According to these results, we hypothesize that a tetraploidization event in A. lyrata allowed the production of viable hybrid seeds with A. arenosa, enabling gene flow between the two species.

KEYWORDS:

Arabidopsis; EBN; endosperm cellularization; interspecies hybrid seed failure; reproductive isolation

PMID:
28115687
PMCID:
PMC5307485
DOI:
10.1073/pnas.1615123114
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center